This is the course outline.
This online course, which is probably unlike any course you've taken, has 13 lessons contained within 3 units that span the semester. The material covers a wide swath through energy use and environmental challenges. Lessons will run for 1 week (summer sessions will have compressed timeframes).
The more effort you put into this course, the more satisfying it is likely to be. Keeping up with the material, completing weekly assignments, and basically being responsible for your own learning will improve your experience and success. If low-effort and low-participation is your style, then lean closer to the monitor, because osmosis is your best hope.
Americans use a lot of "juice." Do you ever wonder where it all comes from?
Unit One covers energy use in the home, electricity generation, and coal issues.
We start with what you use (electricity) and then work back to its generation, and fuel issues.
Hello. Today's lesson is all about energy use in the home. So let's go and look at my home. As you can see currently, it is a snowy day.
And so when we ask about what our energy-- large-scale energy use is in the home, and it is certainly a case of heating in central Pennsylvania. Obviously, in other locations, Central Florida, for example, it would be cooling. But you can see behind me the holes on the top of the roof. That's my air conditioning unit where the air jets come in, 1970 sort of fad.
But if we go and look at where I get my electricity from, my heating from, then it is from baseboard heating. And if you can see behind my right shoulder, that's an electric baseboard. Obviously, I've got electricity going on with lights and other things. Obviously a lot of day lighting as well, with the windows.
So back to heat. Obviously, the issue with heat is we have a variety of fuels we can use. 100 years ago, 50 years ago, there'd be a lot of coal use in Pennsylvania. That's mostly dwindling and only out now in the Anthracite Region, although, natural gas is heavily used as a heating fuel.
Propane, a little bit less, biomass, et cetera, et cetera. But the two big ones are natural gas and electricity. Newer homes, if they have access to electricity-- to natural gas will use natural gas.
Let's see, let's go take a look at some other big items. So the big items would be the water heater, which is in the basement. And that hot water, obviously, goes into the things like the dishwasher, the clothes washing, showers. And so the amount of energy utilized, again, depends on the fuel you use.
Again, you might use a natural gas hot water heater, or you could be using electricity. And depending on how many people, et cetera, and depending on the size of the house, these are the things that impact how much energy you're going to use and, of course, where you are and the particular seasonal transformations that occur. And so things like heating degree days and cooling degree days get covered later on.
The things that are going to impact how much energy we utilize is insulation in the house, air sealing, things like that. Obviously, things like a open fireplace would cause some issues. So in the kitchen, we've got the fridge. It's essentially a heat pump.
We've got a microwave. We've got an oven. We've got various other pieces that make utilization and my life a lot easier. So my microwave, my coffeemaker, et cetera, et cetera.
So we're going to learn about air infiltration. We're going to learn about day lighting, use of deciduous trees to stop the lights coming in-- the light coming in on a summer day. And this type of material is what's going to be covered.
So you can see that tree in front of my house doesn't have any leaves. It's deciduous, and that's helpful for shading. We want lots of light, but we don't want lots of heat in the summer.
A couple of things about lighting, I've got a variety of lights in the house. This would have been a fluorescent light until last year. Now, is an LED light. I do have some incandescents.
And if you take a look up here, I have a chandelier. It's a bit crappy. It's not very good task lighting for my puzzle that I'm doing. So I'm going to have to replace that with an LED.
And over here, I have got-- let's see-- I have got compact fluorescent and an LED light. They're a little difficult to see. I won't buy any more compact fluorescents. And a little LED sort of decorative tree.
So that's the lesson material today. It's about how we use energy in the house, could also be businesses. Of course, whenever we have the creation of energy that we utilize, Be it electronics, watching computers, TV, sound system, somewhere that electricity is being generated. And the way we generate electricity currently, there can be considerable pollution and emissions associated with your use of energy. So anyway, I will see you later.
Electricity powers much of our of life and enhances our quality of living. This lesson covers the contribution of electricity to the home and what we can do to conserve and use it more efficiently (lower bills and reduce environmental impacts).
The lesson will focus on electricity use, energy efficient appliances, home and water heating systems, the design of homes to capture solar energy, lighting issues, and energy conservation.
How electrical energy is generated: one lesson covers electricity from fossil fuels and nuclear energy.
This lesson covers renewables and their remarkable recent growth.
Coal used to dominate electricity generation in the US, currently providing the raw energy for ~30% of the electricity we use. Coal formation, its extraction (from surface and undergroun mines), and the cleaning processes are themain topics.
And with Pennsylvania's rich coal history, mining safety and lots of other interesting pieces of PA history will also be covered.
We will return to all of these subjects in Unit 3 when discussing pollution control issues.
What fuels the perpetual motion of people and goods in our culture?
This unit ties together the areas of transportation, transportation fuel refining, crude oil formation along with natural gas, and the security implications of our fuel system, including a look at the historical picture and political events tied to crude oil.
This lesson covers the perpetual movement of goods, services, and people around the US and areas beyond. While this lesson is dominated by personal transportation, other forms which affect our lives are also discussed.
Vehicle efficiencies, on-board pollution control devices, alternative fuels, and alternate engines such as electric with fuel cell technology are covered.
Crude oil goes through a lot to make it to the gas pump, and to meet operational and environmental regulations at the same time. Crude oil is also transformed into numerous other useful products that we use every day, from lip balm to clothing.
We'll explore these transformations, along with refining technologies, environmental treatments, some simple chemical structures, and oil spill treatments and prevention.
Though the California gold rush years are well behind us, the search for "Black Gold" continues in high gear in many parts of the world, including the US. This lesson covers the formation, discovery, and extraction of "Black Gold", or crude oil, and also natural gas.
Also, the political and economic power of oil, its important qualities, and its historical origins in PA will be discussed.
National security, for any country, is tightly connected to energy supply and ready availability of energy resources.
We'll explore the policies, laws, and international relationships that impact our energy supplies, trade, and military priorities (and actions) around the world. US energy policy greatly impacts the energy systems discussed in Units I and II, and also plays a major role in the environmental consequences covered in Unit III.
How can we balance our energy and environmental needs?
This unit will discuss all you ever wanted to know about acid deposition, smog, ozone hole(s), regional haze, climate change, etc. We'll frame the problems at hand, identify many of the real and perceived causes, and address possible solutions and alternatives to the problems. Prominent themes in this unit are the costs and impacts of our energy use on the high quality of life we enjoy, and global political collective responsibility.
Or as Kermit (the frog, of course) likes to say "it is not easy being green!"
Most, if not all of us, are familiar with the problems of holes in the ozone layer, smog (which is ground level ozone), and regional haze (related to particulates in the air). We've all witnessed these forms of air pollution in one way or the other, and some of us are directly affected by them.
In this lesson, we'll delve into these issues, the facts, and myths associated with them, and the strategies for mitigating these emissions problems (reducing pollution).
Most of us know this topic by what the media calls it - "Acid Rain". But rain is only one way that polluting emissions reach the ground.
This lesson is a look into the causes, impacts, and emission reduction strategies for sulfur dioxide and nitrogen oxides, the two main emission-based pollutants. This topic is heavily tied to the lessons on electricity generation (L02/03) and transportation (L04).
Another fine example of media misrepresentation - they refer to Climate Change, incorrectly, as "Global Warming". This lesson will help erase the confusion by exploring the possible causes to climate change, and its many, many impacts (melting ice caps, sea level rise, etc. etc.).
We'll look into ways to slow the rate of climate change down by reducing the emissions of many contributing gasses, and also explore the topic through the watchful eyes of the international community.
We'll look into ways to slow the rate of climate change down by fuel switching, conservation, efficiency gains, and other approaches to reducing the emissions of the greenhouse gasses.
What lies ahead?
You are surrounded by items that use electricity: computers, cell phones, etc., all while sitting with task lighting, in a space that is air-conditioned or heated (perhaps with electricity). The many conveniences of modern life; flat-screen TVs, video game systems, fish tanks, smart phones, lamps, hairdryers, vacuum cleaners, electric toothbrushes, hot water for washing, heat (or cooling) for your room, the fridge, and the all-important coffee maker. Some of you will still have strands of Christmas lights up!
Considering that this is still only part of your individual energy use, imagine the energy supply needed just to serve the rest of your dorm, office, apartment building, neighborhood, or city. Add in all the businesses, schools, industries, etc. Imagine powering the entire state, or the entire country, and then imagine doing it every minute, of every hour, of every day.
Please watch the following (5 min) introductory video:
Hello. Today's lesson is all about energy use in the home. So let's go and look at my home. As you can see currently, it is a snowy day.
And so when we ask about what our energy-- large-scale energy use is in the home, and it is certainly a case of heating in central Pennsylvania. Obviously, in other locations, Central Florida, for example, it would be cooling. But you can see behind me the holes on the top of the roof. That's my air conditioning unit where the air jets come in, 1970 sort of fad.
But if we go and look at where I get my electricity from, my heating from, then it is from baseboard heating. And if you can see behind my right shoulder, that's an electric baseboard. Obviously, I've got electricity going on with lights and other things. Obviously a lot of day lighting as well, with the windows.
So back to heat. Obviously, the issue with heat is we have a variety of fuels we can use. 100 years ago, 50 years ago, there'd be a lot of coal use in Pennsylvania. That's mostly dwindling and only out now in the Anthracite Region, although, natural gas is heavily used as a heating fuel.
Propane, a little bit less, biomass, et cetera, et cetera. But the two big ones are natural gas and electricity. Newer homes, if they have access to electricity-- to natural gas will use natural gas.
Let's see, let's go take a look at some other big items. So the big items would be the water heater, which is in the basement. And that hot water, obviously, goes into the things like the dishwasher, the clothes washing, showers. And so the amount of energy utilized, again, depends on the fuel you use.
Again, you might use a natural gas hot water heater, or you could be using electricity. And depending on how many people, et cetera, and depending on the size of the house, these are the things that impact how much energy you're going to use and, of course, where you are and the particular seasonal transformations that occur. And so things like heating degree days and cooling degree days get covered later on.
The things that are going to impact how much energy we utilize is insulation in the house, air sealing, things like that. Obviously, things like a open fireplace would cause some issues. So in the kitchen, we've got the fridge. It's essentially a heat pump.
We've got a microwave. We've got an oven. We've got various other pieces that make utilization and my life a lot easier. So my microwave, my coffeemaker, et cetera, et cetera.
So we're going to learn about air infiltration. We're going to learn about day lighting, use of deciduous trees to stop the lights coming in-- the light coming in on a summer day. And this type of material is what's going to be covered.
So you can see that tree in front of my house doesn't have any leaves. It's deciduous, and that's helpful for shading. We want lots of light, but we don't want lots of heat in the summer.
A couple of things about lighting, I've got a variety of lights in the house. This would have been a fluorescent light until last year. Now, is an LED light. I do have some incandescents.
And if you take a look up here, I have a chandelier. It's a bit crappy. It's not very good task lighting for my puzzle that I'm doing. So I'm going to have to replace that with an LED.
And over here, I have got-- let's see-- I have got compact fluorescent and an LED light. They're a little difficult to see. I won't buy any more compact fluorescents. And a little LED sort of decorative tree.
So that's the lesson material today. It's about how we use energy in the house, could also be businesses. Of course, whenever we have the creation of energy that we utilize, Be it electronics, watching computers, TV, sound system, somewhere that electricity is being generated. And the way we generate electricity currently, there can be considerable pollution and emissions associated with your use of energy. So anyway, I will see you later.
The fuel or energy source for our electricity is generated by a variety of fossil fuels (natural gas and coal) along with increasingly more renewable sources (wind, hydro, and some solar) along with nuclear energy. The sources we use the most are the cheapest (this was traditionally fossil fuels: coal and natural gas, along with some nuclear and hydroelectric). It was traditionally more expensive to use more renewable energy (or to clean up more of the emissions from fossil fuels). Advances with wind and solar are occurring so cleaner electricity at competitive prices is available. Natural gas use has also increased dramatically due to a new domestic source (shale gas). So it is a time of dramatic change! If we are smarter about electricity use — through conservation and efficiency gains we can save money and protect the environment.
Success in this lesson will be based on the following things;
As I stand in my kitchen, I realize that all of the various appliances only do a couple of functions: they either heat (the coffee machine, toaster oven, oven, microwave) or do work (the blender, extractor fan). For me, the absolute first thing I must have in the morning is my cup of tea! We’ll use my cup of tea to demonstrate the three modes of heat transfer; conduction, convection, and radiation. The key ingredients for a perfect cup of tea are tea and hot water. The hot water comes from a kettle which is a very simplistic boiler. I know when it has boiled — because as the steam escapes through a small hole in the spout, it whistles. Boiling water requires a great deal of energy to transform liquid water into a gas (steam).
In the case of my range, electric energy is supplying the heat. The electricity supplies a stream of electrons that whiz around in the coil at very high speed (close to the speed of light) until they encounter some resistance. Impeding the flow of electrons produces heat, and so the metal coil (on which the kettle sits) becomes hot. The first heat transfer mode to the kettle is conduction. The metal of the cool kettle is in contact with the metal of the hot heating element, and heat always “flows” from hot to cold, so there is heat transfer. The atoms in the heating element behave a little like slam dancers at a Green Day concert. They will pass on their energy to the surrounding people, making them more active, and in turn passing on their energy to another layer, and so on until the whole concert is full of crazed slam dancers.
Watch the following 1:33 minute video representation of conduction through a metal rod.
Conduction is the transfer of heat energy by the kinetic motion of atoms in a substance. Remember that all atoms have motion of some sort. This is true even for atoms that make up a solid. In this animation, note that the atoms in the bar of metal are vibrating slowly due to their relatively low temperature (in real life, I might add, atoms are vibrating at tremendous speeds, so this is just a representation). Now watch what happens when I slide the bar of metal into a furnace.
Notice that as the metal heats up, the atoms at the end of the rod begin to vibrate faster. The faster-vibrating atoms transfer some of their energy to the slower adjacent atoms. Thus, the slower atoms also vibrate faster, giving them a higher temperature. This is conduction.
I should also mention that conduction works to cool an object as well. When a slower vibrating atom is next to a faster-vibrating one, we’ve seen that the slower atom takes some of the energy from the fast atom. This makes the slow atom vibrate faster BUT, it also slows down the faster-vibrating atom, cooling it. If there are MANY, MANY more “cooler” atoms than warmer ones, then the net effect of the energy transfer is to cool the warmer atoms back to a temperature equal to its surroundings.
Some other examples of conduction include:
hot tea in a teacup transfers energy through a spoon to your hand as you stir in the honey
transfer of heat from a hot cookie sheet to the cooler cookie dough heats the dough and cooks the cookie
hot days heat is conducted into your home through the roof, walls, and windows
Convection is another way in which heat is transferred. It occurs when heat is transferred by the movement of fluids (liquids or gases). In our tea example, you’ll see that when a water molecule heats up, it has more energy, (occupies more volume) and is thus lighter and thermal gradients form where the warmer molecules rise to the top and the cooler molecules sink to the bottom. The cooler molecules are then closer to the heat source and become heated, repeating the cycle. Water molecules will also collide — passing along energy (heat).
Watch this 2:31 summary video about Convection from CentainTeed.
Convection is the second mode of heat transfer. Heat transfer by convection occurs as a result of movement of liquid or gas over a surface. Wind blowing against the building is an example of a gas moving over a surface.
There are two types of convection: forced and natural.
Natural convection occurs when the movement of liquid or gas is caused by density differences. For example, we're all aware that warm air rises. That's because it has a lower density than the surrounding cool air and that's what causes a hot air balloon to rise. And of course, we know the opposite is true. Cool airdrops. In our wall example, the warm air inside the building comes in contact with the cool exterior wall. Some heat is lost to the wall, causing the interior air adjacent to the wall to cool. Since this air has a higher density, the airdrops. The warmer exterior surface of the wall heats the air next to it decreasing the air's density and causing it to rise. And as a result, the movement of the air along the surface of the wall increases the heat transfer. This type of heat transfer is called natural convection. This heating and cooling create convection loops adjacent to both the interior and exterior surfaces. Convection can also take place inside of empty cavities. One example is the movement of air in a double-pane window. In winter, air is heated on the inside surface of the window cavity causing the air to rise. The air adjacent to the outside surface cools and drops. What results is a convection loop inside the window cavity that transfers heat from the inside to the outside.
A second type of convection is forced convection. Here the movement of the liquid or gas is caused by outside forces. If the wind is blowing, the air movement across the outside of the wall will be higher increasing the rate of heat transfer. The rate of heat transfer by convection depends on the temperature difference, the velocity of the liquid or gas, and what kind of liquid or gas is involved. For example, heat transfers more quickly through water than through air.
Some other examples of convection include:
Radiation is how the “warmth” of the sun is transferred to you when you're out or how you warm your hands in front of the fire. It is electromagnetic radiation, and it does not need a medium or direct physical contact to propagate. Thus, it can travel through space. The red color from the heating element indicates that it is so hot that it is radiating energy, and these electromagnetic waves contribute to the heating of the kettle. Some of the more expensive models of stoves use this method of heat transfer primarily. Following is a nice video about how radiation works in a building.
Radiation is the third type of heat transfer. Radiation heat transfer is by invisible electromagnetic waves from one object to another. Heat transfers from areas of higher temperature to areas of lower temperature. One common example of radiation heat transfer is from the sun. When you walk outside on a sunny day you immediately feel the warmth from the sun, even if the air is cold. Heat from the sun is being transferred through space by radiation, in order to warm you. Radiation also plays a role in heat transfer in a building. If you stand in front of a window on a cold day, your body radiates heat to the cold surface of the window and the result is, you feel colder. Likewise, if you stand in front of a window with the sun streaming in, you feel warm as a result of the incoming solar radiation. This type of energy--solar radiation is primarily shortwave radiation. Glass is nearly transparent to the shortwave radiant energy from the sun and as a result, once sunlight enters a room, the sun's energy is absorbed by the walls and the contents of the room and is converted to heat. At the same time, the warm objects in the room also emit radiant energy.
Some other examples of radiation include:
We all have one of these! It is a splendid modern convenience and is an example of a heat pump— a device that moves heat, in this case, to ensure that my IPA is an acceptable cold temperature (being English I would also drink it warm). How does it work?
The case is simply an insulated box, so the heat cannot get in (remember that heat flows from hot to cold, so it would not be correct to say insulation keeps the cold in). At the back, there is a heat exchanger, a coil where the heat from inside the refrigerator can be dissipated—yes, this means that in the summer your refrigerator is pumping out heat which you are removing with the air conditioner (silly, isn't it!) But as heat flows from hot to cold, how did we manage to get it to flow the other way? We used a heat pump, to which we give energy so we can move heat; this is achieved because of the properties of the refrigerant (the liquid/gas that flows in the pipes) and the use of the compressor. The refrigerant will be a liquid with a low boiling point. Thus, we can easily convert refrigerant from the liquid phase into the gas phase.
To do this can require a great deal of energy, but, in this case, we already have the energy in place, the heat inside the refrigerator. Pumping in the liquid refrigerant and allowing it to expand and form a gas will cool the inside (this phase change can absorb a great deal of energy). Then, we can pump it through the coils and exchange the heat with the room. Unfortunately, the gas is not at a very high temperature, and so, the heat exchange does not work well, UNLESS we concentrate the heat in the gas, which we can do with the compressor. This will compress (pressurize) the gas so the heat is concentrated (the temperature is increased by the compression step), and thus the heat exchange will be more efficient. The coils at the back of the refrigerator will be enough to cool the gas down so it will turn back into a liquid, and the process can be repeated. The compressor operates only when it is needed.
Unfortunately, one of the best refrigerants was CFCs, (which stands for chlorofluorocarbons). This inert chemical managed to survive very long times in the atmosphere, reaching very high elevations where it reacted with the ozone layer (in the troposphere), causing the ozone hole(s). More on that in a later lesson, but if you cannot wait, The Ozone Layer Protection (EPA) [7] website will give you the rundown. To prevent the release of CFC's we have moved to other chemicals that are safer: hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). HCFCs also contribute to the destruction of stratospheric ozone, but to a much lesser extent than CFCs.
You'll learn more about this when we get to Geothermal heat pumps (see the helpful animations there where the heat exchange is with the outside/inside of a house rather than from the inside to the outside of the fridge).
On this page, we will discuss 5 types of electric lighting: incandescent, halogen, fluorescent, LED, and compact fluorescent. But to start, let's watch this 1:46 minute overview about lighting from the U.S. Department of Energy.
We light up dark spaces with the flip of a switch and we have been doing so since Thomas Edison invented the incandescent light bulb about 140 years ago. The same type is still used but there are more light bulb options. These bulbs will give you the light you want while using less energy (thus lower emissions and cost associated with that energy production). Initially, we moved to an energy-saving compact fluorescent bulb that uses about 25% less energy. But now it is LED bulbs Ithat often light up our homes and offices. So, replace a traditional light bulb in your living room. Put an efficient LED bulb and you get the same light but with about 75% less energy and Energy Star bulbs last 10 to 25 times longer. Lighting your house used about 10% of your electricity use. So, when looking for a new bulb you'll find more energy-saving choices on store shelves giving you more options but save you money and that's a pretty bright idea.
In the “good old days,” when it was dark outside, people went to bed! Around the American civil war, there were other sources of light, obviously. Candles had been used for a while, and lamps burning sperm whale oil were available. Poor old Moby Dick was a popular choice for this oil and was becoming quite scarce when, fortunately for the Sperm Whale, crude oil was found in Pennsylvania. Originally the crude oil was sold as rheumatism medicine before it was found that kerosene could be produced (separated out of the crude). Kerosene was a clean-burning light source (more about this in another lesson). Town gas has also been used to light towns (town gas tended to be the vapors of heated coal synthesis gas) or in some cases natural gas. However, the naked flame was always a fire risk, and when the incandescent light bulb was perfected, you could have light 24 hours a day, whenever it was needed (providing you could afford it, and there was an electricity supply!)
How many bulbs are visible from where you are sitting? How many are in your home? My guess is that you might have 30+ light bulbs. A decade ago these would probably be incandescent bulbs and it's still a good idea to know how they work. For these bulbs, electricity is used to heat a tungsten filament. This thin metal strand (the filament) gets so hot it becomes white-hot, producing bright white light. The bulb itself is simply an envelope in which we can put inert gases so the filament does not burn. The problem with this bulb is that it produces a lot of heat. This is fine if you are using your light bulb in an easy bake oven, but when you are lighting your house at night in the summer — you are heating the room — which you are probably cooling with an air conditioner! Thus the use of an incandescent light bulb is inefficient. We measure efficiency as the amount of useful energy that we get out of a system divided by the energy we put into a system, multiplied by 100 to obtain the %. While this low-efficiency bulb was acceptable for a long time, it is being phased out through legislation reducing production and use to help aid emission reductions. While this occurred under the George W. Bush presidency and was expanded under the Obama presidency. Some of the changes were reduced or eliminated under the Trump administration (you will see this as a common theme). There is obviously friction between emission reduction and cost (more on this later).
Efficiency = Useful energy out / energy in x 100
At about 5% efficiency, you can see that we are wasting a great deal of energy by using an incandescent light bulb. This is one of the basics of all our energy systems (one of the three laws), we don’t get out what we put in; there is always a reduction or an “energy tax.” We measure how much light intensity comes off a light bulb by either candle-power or lumens. By putting more electricity into a light bulb, we can, to a point, get more light. We measure the “flow” of electricity by the term Watt (W). You might purchase a 60 W light bulb, for example, that will produce 890 lumens of light and should last 1,000 hours of use. If you need more light, a higher wattage bulb will provide more light (and use more energy). Due to this inefficiency, these bulbs are being phased out and replaced by LED or compact fluorescent bulbs.
This is a much better method of producing light as it is far more efficient (x 4 incandescent). That means it is about 20 % efficient which is still not an impressive number. How does fluorescent lighting work? Much of the energy required to "light" a fluorescent light is needed as soon as the light switch is turned on. The electrodes at either end of the lamp are the starting point for the electron to “flow” through the tube (from one electrode to the other). As they pass through the tube they excite the mercury vapor inside the tube; the excited mercury gives off ultraviolet radiation. Unfortunately, that is not very useful for us, as we cannot “see” that wavelength of light. However, we can use this ultraviolet radiation to excite a phosphor coating on the inside of the bulb which, when excited, gives off visible light. The lower rate of energy use (wattage) will however still produce as much light as an incandescent light because of the efficiency increase over the incandescent lighting (look at lumens levels to compare). Offices, universities, malls, supermarkets, apartment complexes will all use this type of lighting, as the light is on for long time periods, often 24 hours a day in some locations. Many of these bulbs are being replaced by LEDs.
As discussed above, an incandescent light bulb produces light by heating a tungsten wire to white-hot temperatures. No wonder it is not a very efficient form of lighting. Fluorescent is a lot better at about 20% efficient (converting electricity into light), but fluorescent lights were for a long time only long tubes. Now compact fluorescent light bulbs are available that simply screw into the same lamps that an incandescent light bulb did. The advantage is that your electricity bill will be less because for the same production of light (how many lumens), less electricity is used. The compact fluorescent bulbs also last much longer than the incandescent bulbs, so they don't need to be replaced as often. Yes, they will be more expensive to purchase but when you look at the lifecycle (how much money in total that you pay), compact fluorescent bulbs make a great deal of economic and environmental sense (electricity comes mostly from aging fossil fuel utilities that produce air pollution). An additional benefit is that less heat from the bulb provides less risk of fire or (they are safer). Now LED's are the better option.
LEDs are small light sources that become illuminated by the movement of electrons through a semiconductor material [9]. LEDs have been around for a long time; the red, green, and blue lights were in various electronics such as my 1970s stereos (the things we used before iPods!) and now in cell phones and many other consumer electronics, from coffee machines to computers. Recently, they have become a lighting option for white light (often directional lighting for task lighting: reading lamps, countertops, etc.) Often there is an array of LEDs to provide enough light. They have a high efficiency (similar to fluorescent), don’t produce much heat, and can last a long time. They are increasingly common in general lighting and have a nicer color than compact fluorescent lighting. They are also being used in traffic lights, streetlights, Xmas tree lights, and other more common applications. They use less electricity, the light is closer to incandescent in color, and they last longer.
We can "see" heat if we use an Infra-Red camera. In the image below, you can see two lamps, one with a Halogen lamp the other with a Compact Fluorescent lamp. The CFL has a higher efficiency because it does not produce as much heat. Replacing incandescent bulbs with compact fluorescent bulbs is a good way to lower your electricity bills. LEDs are however now the better choice commonly.
In the northeast, we spend a great deal of our total energy (note this is not just electricity) on home heating (about 44% of the utility bill is heating & cooling). In other locations, home cooling is the major expense. In some locations, both heating and cooling are required to ensure our comfort. How much energy we will need is obviously weather dependent. The colder (or warmer) a location is, the more energy will be needed, and if the winter (or summer) is long and has many cold (hot) days, then more energy is needed. We can express this impact mathematically using heating degree days (HDD) for our heating needs and the summer equivalent cooling degree days (CDD).
How much energy is needed to heat (or cool) your home is dependent not only on how many days that heating (or cooling) is needed, but also how cold (or hot) it is outside. On a very cold day, you will need to use much more energy than on a slightly cool day. We can quantify this by examining the temperature difference and for how many hours it is needed (we need more heat in the evening/early morning or more cooling mid-day). Heating is needed < 65o F (<18o C), We use this information (HDD/CDD) to compare annual energy usage and to explain why heating/cooling costs will vary due to weather impacts or regional temperature differences (used in determining how much insulation is appropriate). For example in 2019 the Northeast had ~6000 heating degree days but Florida had ~ 2,500 heating degree days. Have a look at the regional map is here [10].
The house with more snow on the roof is more efficient and has a lower energy bill because there is less heat loss through the roof due to better insulation values!
Obviously, we can save energy if we capture it and don’t let the heat out (winter) or let the heat in (summer). We can achieve this with insulation. Our older houses often do not have the required insulation because when they were built energy was cheap, and so the economic incentive was not present (or, as we will see much later, the national energy security was not threatened—yet). Modern housing is required to have certain insulation levels to meet the building code. What these values are will vary by geographic region (related to HDD/CDD). We use R values to measure the insulating property of the material (the resistance of an area of material to heat flow over time). The units are:
h= hours, ft2 is the area, F is degrees Fahrenheit, and Btu (British thermal units) is energy. So, as that is a mouthful, we just report the R-value as the unit.
As this is the resistance to heat flow, the higher the R-value the better the insulating ability. We can increase the R-value by adding more (thickness) insulation or by changing the insulating material to a higher R-value. Of course, if this is a wise investment or not depends on the climate (Heating degree days), how well the house is already insulated, along with the cost of insulation and the cost of heating. So, it makes sense to add insulation when the energy cost is high and the insulation costs are cheap. When energy is cheap, the payback period is too long. That is why old houses were poorly insulated. Now, however, the era of cheap energy is over.
The map below shows the EPA insulation zones for houses across the country. Both cold and hot areas (those with high HDD AND CDD) are required to have higher levels of insulation (higher R-values).
The chart below shows the EPA recommended R values for houses in (Zone 2), where Penn State's main campus is located. The highest R-values are required for the attic. R-values differ based on the area and location in the house (interior and exterior walls for example).
Air infiltrates in and out of your home through every hole, nook, and cranny. About one-third of this air infiltrates through openings in your ceilings, walls, and floors. This provides a means for heat to escape or enter the home. Again this will differ due to area, location, and materials used in construction.
Natural gas is popular because of the (normally) low cost and ease of use (no cleaning up ashes, or arranging storage and delivery, etc). Not all of the houses have access to natural gas pipelines, so they tend to use electricity, or older houses (especially in the northeast) might use a fuel oil furnace. Had this course been taught in 1917, the local area would have been heated with coal. You may have heard the expression of getting coal for Christmas if you had been naughty. Coal was so abundant around the house for home heating, it had little value as far as children are concerned. Before the 1800s, biomass would have been the fuel of choice for home heating.
Burning wood is still used in many nations and was, of course, the method of choice for the early settlers and Indigenous Americans. I still use wood furnaces to supplement my home heating as it is cheaper than using electricity. Cleanup is a pain and I often get yelled at for dropping bark on the floor or spilling ashes but it is nice and romantic on those cold winter evenings! Burning wood works because solar energy is stored in the plant in the form of chemical energy and then released as thermal energy during the combustion process.
Biomass is going to again contribute more to our energy mix. See the next lecture for why. Hint: Renewable Portfolio Standards!
Below you will find two videos from the US Department of Energy. They both provide a nice overview of home heating.
The first one, Energy 101: Home Energy Assessment (3:30 min.) discussed what a home energy assessor looks for when evaluating a home for efficiency, including insulation and air infiltration as described above.
In any season a leaky (high air infiltration) home costs money. How do you stop it? It starts with a comprehensive home energy checkup. That’s a series of tests and inspections to find out where your house could be more efficient. The end goal is to save energy, save money, and make your house more comfortable. Installing energy-efficient lighting and appliances will help. So will creating a sealed barrier around your house hence minimizing the leaks. Upgrading your home to save energy can put anywhere from 5 to 30% of your energy bill. To get a thorough home energy checkup, you’ll need some help from a professional. Look for a home energy technician, called an auditor, in your area. Now, in this cold-weather evaluation, the auditor starts on the outside, looking for problems around walls, joints and under the eaves. If there’s not a tight fit, you’re losing energy and money. Next the technician might head up to your attic to check for leaks in the top of your home barrier. That trap door could be a culprit, letting cold air pass into the house. A big part of the checkup is determining how well the insulation insulates. Insulation should be correctly installed in between all areas of the house frame. That means it needs to be evenly applied and not just jammed in spaces. And of course, if the insulation has fallen down, it’s not working. Your energy auditor will inspect the holes where electrical lines pass through. If they’re not sealed, they’re leaking. Then it’s down to the basement. Your furnace and water heater could be wasting energy. The auditor will check to see how energy efficient the furnace is. Furnaces generally lose efficiency as they get older, and it could cost you more to keep yours running than to replace it with a new one. Maybe all you need is a new filter. Some people haven’t changed their filter for months, even years. That gunk clogging the filter means your furnace has to work harder to heat your home. If the water heater is several years old, it may not be efficient, and if it isn’t insulated, it’s also losing energy. Now it’s on to the ductwork. The technician will inspect connections to make sure they make a tight fit. They have to be sealed to keep the warm air going where it’s supposed to go. If the screwdriver can go in the hole, it means one thing for sure: Money is going out. Now for the blower door test. The energy auditor will close all the windows and doors and anything else that let outside air in. This special fan will depressurize the home. The idea is to suck air out of the house, allowing outside air to rush into the home through all those openings you didn’t know about. OK, so with the windows and doors closed and the fan running, leaks are easy to spot with an infrared camera. In winter the auditor will scan the interior of the home looking for cold air rushing in. Here the darker the color, the worse it is. These black spots mean one big air leak. It’s an eye-opening experience. For this house, the recessed lighting fixtures are big problems. The auditor will also take a look at the kind of light bulbs in those fixtures. If they’re incandescents, they’re using a lot of energy. Warm compact fluorescents are an energy-saving alternative. So the home energy assessment reveals ways that energy escapes your home, costing you money. The good news is you’ll have a comprehensive home energy report showing which efficiency upgrades are right for you and where to stop those pesky leaks.
Now watch the 2:43 minute video about daylighting.
Windows do more than provide a great view (or not). When we maximize the use of windows to reduce lighting and heating needs It’s called daylighting. Daylighting combines lots of things – everything from the type of window, window placement. and interior design – to control how sunlight comes in. They all work to maximize benefits from natural sunlight. (Music.) Check this out. Windows that face south are best in the U.S. They let in the most light in the winter months, but little direct sun during the summer, keeping the inside cooler. North-facing windows are also good for daylighting. They let in even natural light with little glare and little summer heat. Windows that face east and west don’t work nearly as well for daylighting. They do provide lots of light in the morning and afternoon, but it often comes with lots of glare and excess heat during the summer months. (Music.) Have a look at this energy-efficient office building. The windows team up with skylights to provide most of the light you need. Notice the light color of the ceiling. It reflects and enhances the daylight so that it fills the room. And what about all the overhead lights? Most of the time, you don’t need them. To account for glare, this office building placed hoods outside around the windows. The hoods also cut down on summer heat, keeping the office cooler and more comfortable. On the inside, louvers or tinting reduce glare and also direct light to reflective surfaces inside, allowing plenty of natural light to come into work areas. One big help to daylighting is the window technologies available today. Windows are now way more energy efficient. They insulate while still letting the light you want in. And have a look at this. It’s an electrochromic window. This special window changes with the brightness of the sunlight outside. As the sun tracks across the sky, it darkens to keep excess heat out. It’s like giant polarized sunglasses. Daylighting can have a positive effect. Studies have shown that with good daylighting at the office, productivity goes up and absenteeism goes down, and that’s good for the bottom line. Natural lighting and heating means you use less electricity and lower your utility bill. And the more natural lighting, the more money you can save.
The previous page explained what influences how much energy we need to heat or cool the home along with some of the traditional fuel choices. A modern approach however can also use a combination of electricity and geothermal (renewable energy) to heat and cool the home.
This is perhaps one of the very best methods of both heating and cooling your home or office (and you also get cheap hot water in the summer). It works because unlike the air temperature which can vary greatly, the temperature of the earth is relatively constant (once you get deep enough). Here I am not talking about going very deep, only a few meters; once you start getting deeper, then the temperature of the earth increases as you get closer to the hot core. But at a few meters down, the temperature will be a constant value. It is called geothermal energy because it is energy from the ground, but it is actually mostly stored solar energy.
Not only can this stored solar energy be used to heat your home, but it can also cool your home and provide hot water in the summer.
Watch this introduction to geothermal energy from the Department of Energy (2:31 minutes)
We all want to save money heating or cooling our house or office, right?
The answer may be under your feet, literally. Much of the heating and cooling can come from the ground, below the surface, with something called a geothermal heat pump. You see, below the frost line about 10 feet down, the Earth maintains a nearly constant temperature of 54 degrees. We can tap into this energy to provide heating in the winter and cooling in the summer.
OK, now, here’s how it works. Bury a loop of pipes called a heat exchanger just below the surface, and fill them with water or a water and antifreeze solution. During the winter months, the air is usually cooler than the temperature below ground. The solution circulates in a loop underground and absorbs the Earth’s heat. This heat is brought to the surface and transferred to a heat pump. The heat pump warms the air, and then your regular heating system warms the air some more to a comfortable temperature. Finally,
ducts circulate the air to the various rooms. Now, a huge benefit is that the geothermal system doesn’t have to work as hard to make people inside comfortably warm, and you save lots of money on your heating bill. In the summertime, the system works in reverse. When it’s hot outside the temperature below the surface is cooler than the summer heat. So the fluid in the loop absorbs heat in the building and sends it underground. The ground’s lower temperature cools it, and it’s circulated again and again. Now you’re saving money on air conditioning.
Now, this church uses a large geothermal heat pump to heat and cool the building. It has a very big parking lot, which lets it spread out is loop horizontally. But if you don’t have all that space, you can go straight down and use a vertical loop system instead. Geothermal heat pumps can be used just about anywhere in the U.S. because all areas have nearly constant shallow-ground temperatures, although systems in different locations will have varying degrees of efficiency and cost savings.
The constant temperature of the Earth just below our feet is a sustainable resource literally in our own backyard. It’s a clean energy source ready for us to use to heat and cool our homes and buildings while
So, it is a cold winter day, the outside air temperature is 30 °F, but the temperature of the ground 10 feet down is a balmy 50 °F. By putting pipes in the ground, we can exchange the heat from the ground to the house. A fluid is pumped through a closed loop of piping into the earth where it warms up. See more detailed information on the Geothermal heat pump [16] page of the Dept. of Energy website.
In the image to the right, pipes enter and exit the vertical hole in the ground. Most systems will be closed-loop systems like this, although you could take the water out of the ground in an open-loop system as the water temperature will remain constant.
So, it is a balmy 90 °F outside, but the ground is a cool 50 °F. We can now move heat from the house into the ground. All we need to pay for is the electricity to circulate the cooling fluid. You can also produce hot water via this method, more cheaply than using electricity, to heat cold water to hot water for your showers or clothes washer.
Geothermal heat pumps are sold by the weight of the cooling fluid. Some of the facilities require lots of pipes to provide enough heating and cooling for large buildings. This is the barrier to using a heat pump - the high initial cost (capital cost). After that, the cost of electricity is low and no fuel costs, thus producing cheap heating and cooling without air pollution (apart from the electricity needed to run the pumps).
Okay, the above is a tad simplistic. We could, if we wanted to, flow the heating/cooling fluid around the house, but we tend not to. A cooling system works by turning a liquid into a gas. This liquid to gas process requires energy, and so it cools its surroundings (we actually lower the pressure surrounding the liquid). We use a compressor to compress the gas and turn it into a hot gas. We also need energy (electricity) to pump the fluid. This is how we would cool the house by expanding the liquid to a gas (absorbing heat) which cools the house. The gas is then compressed to produce a higher temperature gas (heat exchange here to get the hot water for the house) and then allow the hot gas to heat exchange with the earth, cooling the gas so it turns back into a liquid, so we can do the expansion again and cool the house.
To heat the house, we pump liquid into the pipes (which are in the ground). There, the liquid warms up and forms a gas. Unfortunately, the gas is not hot enough to directly warm the house, but if we increase the pressure, we can turn the gas into hotter gas (concentrate the heat). This process does require electrical energy. But, for a little energy, we are getting a great deal of free energy from the geothermal source —the earth. Now that the gas is much hotter than the air temperature, we have a heating cycle.
The geothermal heat pump in this house provides all the heating, cooling, and hot water needs for the entire house. For a home of 1,500 square feet with a good building envelope (well-sealed so a low air-infiltration) and a geothermal heat pump, energy costs are about \$3 a day. This is much cheaper than the average energy cost but they are not cheap systems to install at about $7,500 in a new house, but they only use a small amount of energy (electricity), and they both cool and heat the house (and provide hot water). Payback time for this investment is about 6 years, so it is worth doing. However, the cost is more expensive if the house does not already have the ductwork in place for air handling. If you look back at the insulation page, you will see that the Department of Energy thinks that geothermal heat pumps can be used in PA. I only know of a few houses, however, that have an in-ground heat pump.
We will see that, in comparison to the other methods of heating and cooling the house, this will have a much lower environmental impact.
In lesson 2, we will also discover that the energy from the much deeper ground can also be used to generate electricity. Don't confuse the two types as it is a very common error:
This is another one of the big energy users (hence expenses) in your home. Generally, water heating will rank third after home heating and cooling. Many of our appliances are now much more efficient than they were 10-12 years ago. I think it might have something to do with efficiency limits mandated by the government for the area in which you live. One of the problems and advantages of the water heater is that she is a hard beast to kill and struggles on for years before the lingering death comes to a halt and your hot water heater fails.
The cheaper options are natural gas (assuming gas prices are not too high), oil, and propane, but since natural gas doesn't come to my house, I use an electric hot water heater which is more expensive.
Of course, the less hot water you use, the lower your electric and water bills will be. We use hot water for things like bathing, cleaning dishes, washing clothes, and, if you have an old house, perhaps even heating your home with a radiator.
The following are some ways to reduce your electric and water bills. Take a shower, rather than a bath. Showers use less hot water than baths. Cold showers are a bit extreme but would save both water and energy! (You could always shower with a friend to conserve.) Washing clothes in an efficient washer also helps. Aerators lower the water flow for washing hands, etc. Turn down the thermostats on your water heater. Water heaters have 2 thermostats, one each for the top and bottom element. Don't leave the tap running too long; insulate your pipes and keep the water heater in a heated part of the house rather than the deepest, darkest spot in the basement. Purchase a new water heater if you are still using an old model. These approaches will also lower your utility bills.
Water quality can also impact the cost of water heating. Hard water can add scale to the pipes and hinder the heat transfer from the element to the water.
Watch this (1:27) movie to see the effect of hard water.
[Camera is zoomed in on a shower head.] Dr. Mathews: Hard water is certainly a problem in our area. And you can see pretty simply from the shower head that these hard water stains have affected it. One way I can clean it is by soaking it in a weak acid such as vinegar. [Camera shows the shower head in a glass bowl with a bottle of vinegar next to it] Dr. Mathews: By leaving this here for several hours it cleaned up the system quite nicely. Now if you have hard water whenever you are boiling water or say boiling a lot of water in a pan, kettle, or an electric kettle, [Camera zooms into the cleaned shower head.] you are going to start getting this coating in the metal. The hard water stains are going to impact the ability to do heat transfer and increase your heating costs. Now you can use vinegar to clean things like your coffee maker and things of small scale. You certainly wouldn't want to use it in a very large device like your water heater. So there your options are to replace the heating element if it is electric or one of the other things you can do is to prevent the problem from forming in the first place. And that is by taking your incoming street water, municipality water, and treating it to avoid the calcium and magnesium going into the system. There is a variety of techniques from adding salt, to magnetism, to osmosis, to all these other weird and wonderful things. But the bottom line is if you can do this you are going to have a much better heat transfer efficiencies and your hot water heating, which is a significant expense for most houses, will be considerably lowered. [Video ends]
This pool owner (one of my friends) uses active solar heat to keep her pool warm in Orlando. The solar panels on the roof warm the pool water which is pumped through the tubes when the thermostat indicates that the water from the solar heater is hotter than the pool (and the pool temperature is below the desired setting). The cage is to keep out the insects. Solar water heating (for pools or home hot water) is perhaps the most economic use of solar energy after passive solar heating.
Before we can work out how a microwave oven works, we need to know what a microwave is. The electromagnetic spectrum consists of various wavelengths of visible light (colors) as well as radio waves, X-rays, etc. There are two simple parameters that change the utility and the behavior of these various waves: wavelength and frequency. The example below uses a frequency slider to adjust the frequency/wavelength of the wave.
Let’s explore a simple model of how oscillation frequency is tied to the wavelength of electromagnetic radiation.
The frequency at which electrons oscillate is essentially set by the temperature of the matter in which the electron resides. Lower temperatures yield lower frequencies of oscillation. Here, we’ve set our temperature on the low side, and you can see the molecule oscillating fairly slowly, or in other words, at a low frequency. The wavelength of the emitted radiation is also relatively long.
But, when the temperature increases, the oscillations get faster, which makes for a higher oscillation frequency. This high frequency means that the emitted electromagnetic radiation has a relatively short wavelength. For comparison again, we can decrease our temperature to watch the oscillation frequency slow, and the wavelength of the emitted radiation increase.
NASA's web page on the Electromagnetic Spectrum [19] provides a brief, straight-forward discussion about the topic that I expect you to take a look at. As you read, make sure you understand at least one use for each classification of wavelengths. For example, radio waves carry radio signals. What are IR and UV useful for?
After reading the NASA page, you should know that the wavelength of microwaves is about a few centimeters (cm). This energy enters the food or liquid (placed in the microwave) and excites the molecules within, causing them to vibrate more. The technical explanation is that as the molecules move more, they have more kinetic energy, which, in the case of molecules, we call temperature... thus heating up the food, very convenient.
We will find out in lesson 2 that the sun is the source of nearly all our energy (nearly all of the renewable energy and the chemical energy in the fossil fuels). In the winter, we crave the warm rays, and in the summer, we may hide from the sun and its oppressive heat. For most of us in America, we could obtain all our home energy needs directly from the sun year-round but it would require a quality house that was well designed and placed. For the rest of us, however, some of these solar options are a good way of reducing the heating, lighting, and cooling bills. Here, passive solar heating options are discussed. Passive means that no external energy is used. It is, in essence, good design (no pumps, no electrical energy).
Face the house towards the south (in the N. hemisphere) to maximize the exposure to the sun. Unfortunately, most of our homes are situated so they face the roadway regardless of the orientation towards the sun. Nor can we physically move our houses very easily, but keep these things in mind when you build your 4,000 square foot palace. Natural lighting reduces your electricity bill and reduces your pollution footprint. Most of us are interested in capturing the sunlight so we can live in bright locations. (Without sunlight, you can become depressed and lose out on vitamin D. Submariners, for example, have UV lamps so they can get a bit of a tan and avoid becoming "SAD" seasonal affective disorder). If you live in a very hot location, you might consider doing the opposite to prevent the solar energy from entering your house.
You need windows, of course, to let the light in. Have large windows at the front of the house (facing south) and smaller windows on the north side of the house. The traditional problem with windows has been that they let light in but also let heat out. The old window is both an energy source (in a sense) and an energy drain.
With modern windows, the insulation properties have dramatically increased with improvements and new materials, surface coatings to reflect certain wavelengths of light, and double or triple glazing with halogen molecules such as Xenon in between the panes. With all these changes, the window can be an energy source for the home rather than an energy drain. The materials and xenon are, however, expensive, so these windows do not come cheap.
You can plant trees that shed their leaves (those would be deciduous trees) and can also have overhangs on your house to limit the sunlight entering the house during the summer months when the sun appears to cross the sky at a higher angle. Once the (solar) energy is in the house, it needs to be stored. Even in desert locations, the day may be scalding, but the nights can be very cold. Our passive solar house needs a thermal mass to absorb the energy and radiate it back to the house during the night. Brick chimneys, brick walls, and adobe floors are often used. The house will need to have good insulation, also, to prevent the heat from escaping in the cool evening and nighttime hours or get in during the heat of the day. Heavy insulating drapes and airlock type doors can help prevent heat loss. Air leaks are also a significant source of heat losses/gains in many older houses.
I am not 21 feet tall. But this image does help explain why we think the sun is hotter during the hours of 12 to 1 in the afternoon. If the same picture were taken then, the shadow would be much smaller (okay, small bulge where my waistline is losing the battle of the bulge!) The sun is more or less directly overhead at noon and the same rays are concentrated over a smaller area. In the early morning, the same rays fall over a larger area (hence my 21-foot long shadow); they are less concentrated. The sun does not know what time it is and so does not become hotter or colder on our time schedule! If I took the picture in the winter at the same time, my shadow would be longer still.
We will cover photovoltaic cells in the renewable electricity generation pages (lesson 03) where we cover generation at the utility scale. You can also add solar panels to your roof or to a community solar project (a collection of panels where you own the panels but that are clustered together away from your residence but still locally placed). By adding solar cells, you reduce your electricity consumption from the grid and are using a cleaner energy source.
These sit on the outside of many of our homes and apparently at least once every 2 months someone comes and reads the dial (I have never seen this elusive individual).On the bottom, there is a wheel that spins. The faster it spins the more electricity you are using. Try looking at 3:00 AM do you think you will be using more, the same or less electricity than noon? We are now moving to digital smart meters that can be accessed remotely.
When you are a homeowner, a trivial thing, like the temperature, impacts you where you notice it the most, in your wallet (or purse). If you have electric heating and cooling in your home (I have 1,600 square feet of finished living area), it is a considerable expense. Waiting for the dreaded electric bill in February is just one of the many joys of homeownership awaiting you! We have seen that our use of appliances requires energy.
In the past, the electricity market was regulated. This means that instead of using market forces, the price of electricity was controlled by a regulatory authority. If you moved into State College, home of University Park campus and Beaver Stadium, before 1996, you would have had no choice other than to purchase your electricity from Allegheny power. They, in return, had a guarantee of a catchment area for customers. To ensure that this would not be a monopoly (a single provider who can set their own price); the maximum price that they could charge was regulated. Allegheny Power, being a private company, still needed to make a profit for the shareholders and have the money to meet the environmental regulation expenses (more on this in Unit 3). Many of the states looked at their neighbors and wondered why their constituents were paying more than the constituents of other states. Deregulation opened up the generation component of electricity so there is now competition (also with natural gas). Competition helps to lower prices and is the American way! (Well, the US still regulates milk prices!) Most of the US now has a deregulated electricity market. Unfortunately, this deregulation also caused challenges related to electricity planning, delivery, reliability, and emissions. The management of electricity generation and delivery is regionally controlled by either a regional transmission organization (RTO's) and often cover multiple states or parts of states. Or are locally controlled in regulated systems.
We have a choice of electricity generators to choose from. Listen or read my explanation below
Listen to my audio explanation [26].
Or read
In Pennsylvania when you move to a new area like I did coming to State College essentially whoever provided your electricity was more or less a controlled monopoly. I had to go through Alleghany Power, they were the only people that could sell me electricity. Now we have an electric choice. I can decide how I would like the electricity made. Now it is somewhat of a con because if I say buy wind power there is no way of getting those electrons from wind delivered to me. It is just electricity that gets dumped into the system. And I will take out the appropriate quantity of electricity. And so it is not quite right in that you are choosing how your electricity it made. But you are choosing how components of the electricity are made. And of course, you can either go with the cheapest, which is generally coal, or you can go environmentally sensitive and decide to go with wind. Either way, what you are picking is how the electricity is made. The delivery, and the transportation across the country, and delivery to your home is, however, done via the existing entity, in this case, Alleghany Power. Now, this was done for several reasons. One if which is because with more choice and competition it is hoped that the electricity price will be reduced. And, in fact, they certainly will be when the transition period payments go away. And so that is certainly going to help lower the cost of electricity. Which currently runs about six or seven cents per kilowatt-hour.
Since this audio was produced, the cost has increased to around 13 cents per kilowatt-hour.
Your electricity bill currently consists of 3 components: generation, transmission, and distribution. Bottom line is that competition and choice drive down prices or give the ability for green options (of course, at a cost!)
Watch the following 4:53 minute video about how electricity supply needs to meet the demand.
OK. So today, we're talking about electricity and very much the piece that is the supply needing to meet the demand. So this is very much a case where this has to happen. I can't have electricity storage in the wires. They would heat up. They would melt. That management is quite interesting. And so you have to have the electricity as needed. Now, the piece that's obviously missing is storage. And if we get that right, then we're on to a game changing scenario. But right now, we have pump storage primarily is how we do this.
So let me remind you of a couple of things. So I'm going to show you three cases of what the electricity demand looks like in the week. And so we have Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. And so this is some sort of measure of demand. And what typically happens is at night, we're using a little bit of electricity, but we're using some. We have these sort of weekly peaks. It might peak around four or six PM depending where you are. And then the weekend typically has a lower demand cycle. So along these lines.
I've drawn that to be relatively uniform. But if we just take a look, this is the lowest amount of electricity used during the week. And that would be the baseload. And, of course, maybe we'd have a day, that might have a higher usage than others, et cetera, et cetera.
But let's say that this is April in Pennsylvania. We don't use a great deal electricity. We are not heating. We are not cooling a great deal in Pennsylvania. We're still using lighting. We're still using hot water. We're still washing clothes, et cetera, et cetera. And, of course, industry is still running. This is probably why we see a reduction in commercial and industry over the weekend.
But if we look at some other cases-- let's go look at a case now where it is the demand for the winter season. And here we still see the same sort of ups and downs. Maybe there's a warmer day, colder day. And you can see that our base load is considerably higher. And we said this was winter, so let's say it's January. We're heating and some of us-- about half of us will use natural gas for heat. So that wouldn't come into here because this is electricity supply. But then the rest of us are using electricity and oil and other pieces.
If again, we do this for the summer. And so let's say, July, which is hot and humid and a bit rotten in State College, again we're going to see a very large peaking. Maybe it was a hot day. Maybe it was a cooler day. And we have a also much higher than the baseload that we had over here.
So what we've seen is there is considerable variability between the seasons. So we have a lower electricity use in April in Pennsylvania. We see a very significant-- almost a doubling, perhaps more than a doubling between the baseload and the highest generated need of electricity, highest electricity demand. Obviously, winter and the summer is where it might peak. In this particular case, we can see that the peak was actually in the summer, which is the case for Pennsylvania.
And so we have choices in how we get there. We've obviously seen that we can generate electricity with the fossil fuels. We can generate with nuclear and with renewables. But we need the policies to be in place so that we can achieve the right balance and have a stable, reliable, resilient grid where electricity prices are cheap. And so that's the next segment.
Now watch the following 8:19 minute video about how we meet the changing demand for energy.
So let's look at a little bit more detail about how we meet that changing demand. So let's just pick again. Let's pick a particular day.
And so here's our baseload. And we have a increase in electricity use. People are getting up, turning on coffee makers, making breakfast, turning on lights, having showers, using hot water, going to offices, turning on electricity. It reaches a peak.
They've gone home. They've turned on more appliances. They're cooking. And then there was a decline. And then it starts up the next day again. And so it might look something like that.
If we're in somewhere interesting like California, because they've got so many solar, you might see actually a reduction in demand right there, just at the peak of wherever noon is, as all the rooftop solar are maximizing their electricity production, and there isn't as much demand. But let's just ignore that.
So what do we use for the baseload? Well, for our baseload we want to use the cheapest electricity. And so here, in the old days that would be very much a combination of coal, nuclear, and hydro.
Now, we're limited in how much hydro we have in many locations. We're limited in how many nuclear power plants we have. And so we have a bit more flexibility in the number of coal-fired power plants that are producing electricity.
And so how do we meet this changing demand? Well, I don't want my nuclear power plant going up and down. It's not designed to do that. Hydro can certainly do that. But if we have a lot of hydro, we want to be using that hydro. And coal doesn't like to go up or down either.
And so we have a large number of plants operating. And so over some of these systems that cover multiple states, there might be 50, 60.
So this is the large coal-fired power plants that are running. And they might start off at 60% of their output and increase a little bit more. We might add a little bit more hydro coming into the system.
And so there was a system where which when it was regulated, we would control how we were meeting this electricity demand. And at the peak, we were paying much more for that electricity generation.
And so, again, in the old regulated days, this would have been natural gas because it was expensive. But we would turn on more power plants and more power plants. We would have the cheapest running the longest time and running at the higher capacity. And then we would turn more and more on.
Coal doesn't like to be turned on and off. And so we would use smaller and smaller natural gas peaking units, and we'd add more into the system. And so this was how we did things under the regulated.
And so even though when you pay for your electricity you had a standard cost, you can see that-- per kilowatt hour-- you can see that we have a variable cost going through the day.
So it was decided that we might be able to do better by going to a deregulated system. And so now, and in the change that we've seen if we take the same system, we have still our same baseload. But now, things have changed price-wise. So now we have significant contribution from wind as well as hydro. And that is growing.
We're likely to see solar come in. And solar, of course, is going to be coming in a particular contribution. It's not going to be running at midnight unless we have stored thermal solar, which we have seen with some of the concentrated powers.
We have nuclear still in the game. And that's producing as much electricity as these two pieces combined. Solar is not yet contributing very much in Pennsylvania to our total electricity supply.
But there are locations in the world where it's much higher. And there are places in the United States where it's much higher. And it's expected to grow.
We are still running coal. We are still adding in other pieces. But we have natural gas. And natural gas right now is very cheap. And so that went up dramatically, primarily at the reduction of coal.
And so now, as I'm writing this, it's about 30 something percent in each case. And so still heavy on the fossil fuels. But again, we're turning on the systems. But we no longer are able to just keep on turning more and more expensive units on because we have renewable portfolio standards.
And so now we have our wind and our hydro, which are now getting quite cheap contributing to our baseload. There's intermittency, obviously, in the wind and in the solar. And so that's problematic.
Again, I don't want to cycle my coal plants up and down. I don't want to cycle my natural gas plants up and down. And so we have an energy policy that was designed for this system that's transitioning into this system where we're competitively bidding in. And we need a system that's going to be reliant.
So here, everybody got paid/ In the regulated system where this is deregulated, if the system had a coal plant that wasn't used, everybody still got paid. It would have been used when needed.
Here, we're all bidding in when prices go up and down, then we have this system where we're checking very cheap. We're required to take some of our renewables. I'm requiring much more cycling up and down in these locations.
Again, we don't do it with nuclear. Nuclear is running a little bit harder. But every time the wind drops, then these other plants have to come in. Natural gas is very much that workhorse for being able to meet this changing demand. But there are limits on how much we have.
And so the advantage of this is that overall our electricity price is cheaper than we paid over in this system. The advantage of this system is the level of control. We have the ability to make decisions over the long-term and know what's going to happen ahead of time with our emissions and our prices.
But the policy side of this has yet to catch up. And, of course, the changing price of wind, and of solar. Anyway, those are the challenges that we face-- more in the lessons.
Here are examples of weekly electricity demand cycle for various months. Note that the day and time has an impact on demand. Also, these are averages so the variance due to weather (especially cold/hot days and holidays are muted). When you use electricity it has a very significant impact on the cost to generate that supply (the peak will be more expensive than the electricity generated for the trough).
We use a great deal of electricity regardless of the time of day. But there are daily and weekly influences. Most of us will sleep in on a Sunday when many of the factories and some of the shops are closed. We will also use less electricity at night when the nation sleeps (I know you are probably reading this well past midnight!) Think about the problems this demand cycle creates. We do not have a good method for storing electricity (with the exception of pumped storage and some emerging advanced battery options, more on that in the next lesson), so the supply must equal demand or it is blackout time. From the above graph, it looks like we need to go from the lowest output, which we call the baseload, to almost 1.7 times that value in a 24-hour period (July). We also need to do this safely (nuclear reactors do not like having to quickly increase or decrease output) and cheaply. Thus, the baseline electric load is generated by the cheapest utility sources that run 24 hours a day. As the demand increases, the generating capacity will be increased, and additional units will be brought online. Finally, if you need the electricity, the highest cost generators are turned on. With smart meters now being available, there are incentives to switch to using more of the electricity during the lower demand times as that electricity is cheaper to generate. So, dishwashing and clothes washing machines have delayed start options so they can be run at night.
The seasonal demands on electricity generation can also result in dramatic swings in demand. On cold winter weeks and hot summer days, the electric heaters or air conditioning units crank out hot or cold air 24 hours a day. So not only does supply need to meet demand but there needs to be excess capacity for those temperature extremes and to allow utilities to shut down for routine maintenance. The economy also has an influence. There is less pollution (lower electricity demand) during economic depressions.
The U.S. electricity transport and distribution system have grown into a complex network containing according to the EIA "the U.S. power grid is made up of over 7,300 power plants, nearly 160,000 miles of high-voltage power lines, and millions of miles of low-voltage power lines and distribution transformers, connecting 145 million customers throughout the country".
We tend not to transport electricity over great distances. There are problems with electricity losses over distance, but, more importantly, the connections from one part of the country to another are not there. We can send electrons (which is, after all how you are accessing this material) across the country but we cannot send lots of electricity. The capacity to carry enough of the electrons does not exist. Thus, if California was experiencing an electricity shortage, we in Pennsylvania could not increase our output to help. Thus instead of a national network, we have Regional
This inability to transport electricity also means that industries that are electricity intensive tend to be close to cheap sources of electricity such as hydroelectric sites. (Las Vegas baby!) Adding intermittent renewable energy (such as wind and solar) into this mix is a challenge.
Somewhere in your house, there is a circuit box containing a number of circuit breakers. I can remember when fuse boxes were the standard. These contained huge fuses that would simply blow if the electrical current overwhelmed the circuit. Perhaps you've had this exact experience when running a hair dryer or space heater in an older house, sending you to the basement to find the box. Hence, the advantage of breakers over fuses - simply switch a breaker back on after it shuts down, but for a fuse, you'd better hope you have a backup waiting, or it's wet hair for you!
Breaker boxes are where all the electricity used in your home enters the house and is distributed to the electricity-hungry devices, such as electric dryers, electric ovens, electric heated hot tubs, and to all those lights, computers, fans, video game consoles, TVs, etc. The question is; How does the electricity make its way into your home?
Now, if you go outside and look around, odds are you will be able to find the meter, which conveniently keeps track of all the juice you use, and then the transformer, a drum-shaped piece of equipment sitting atop a pole somewhere close to your house. This has the important job of stepping down the voltage entering your home from several 1,000 volts to 240 volts. Volts is a measure of the "pressure" behind the electric current, and most home appliances use 110 V, but those dryers, hot tubs, etc. will need to have more electrons than the rest of your appliances, so a higher voltage is needed to "push" those extra electrons along.
In the images above, the electricity meter measures how much electricity you use, so the company can bill you for all those lovely electrons (Kwh). Poles follow the roads, carrying electricity to each of our dwellings. On those nights when you're forced to sit in the dark, odds are that the problem is at the transformer (right image). Lightning, falling tree branches, overzealous squirrels, and drunk drivers all take a toll on these poles and wires, and when they get disrupted, we go back to the age of the candle.
Up atop the mountain, the high voltage lines carry electricity over the mountains, rivers, and highways. Unfortunately, we have not been building new lines and are running out of carrying capacity for electricity. (Recall the blackouts?) For those of you who like Yoga: Ohm's law states:
A bit of magic mathematical manipulation and P=I2R
(don't worry about memorizing the equations here)
The losses we obtain by flowing electricity through wires (which causes them to heat up) is proportional to the current squared and the resistance of the wires. This is why we use high voltage lines, to keep the current low. For the math impaired, doubling the current results in quadrupling the losses, doubling the resistance only doubles the losses. Thus, we use very high voltages, 155,000 to 765,000 V, to do the long-distance trip at about 300 miles range.
These substations have switches and transformers to regulate the flow of electricity. Larger ones are close to the utility where the electricity is generated. In Lesson 2 we cover the wonderful world of electricity generation.
Note that our demand for electricity tends to increase as the population grows, and as we use more and more electronics. This puts an ever-increasing strain on the generation capacity and distribution network.
One of the items that we will come back to is the challenge of supplying electricity with the challenge of intermittency of renewable energy (specifically solar and wind). The following figure shows data for Spain for September/October. Notice the variability in the electricity generated by wind and solar (concentrated solar thermal in this case). Solar will have the obvious peak in the day with some overlap into the evening (solar thermal plants) but will also depend on the sunny days. The wind is also variable with some days having poor solar and poor wind (this would be a bad day in Germany because of their reliance on both wind and solar). Thus, we need to have the ability to generate much more electricity on those days and the electric grid has to cope with the variable renewable supply that adds extra stress. More on this later.
So as we are discussing electricity demand it is important to recall that the answer that is always right in aiding the reduction of pollution is conservation (not the only answer, however). Surprisingly, your local utility organization is happy to help you conserve electricity. Given the very large capital cost required to build a large utility, the more we can conserve, the longer that new utility construction can be delayed. Thus, assistance with weatherization can be obtained in some areas courtesy of the local utility. In the UK, it is common to have 2 prices for electricity: a peak demand price and an off-peak demand price. Similar to many service industries, if they lower the prices for certain times, more people will use those time slots. Hence, dishwashers, clothes washing and drying–appliances often have timers to turn them on when the electricity is cheaper (after 10:00 PM). Now the utilities can run the cheaper sources at a higher capacity, longer. We are moving in a similar direction and beyond with the adoption of smart grid technologies and smart meters that know when the electricity is used, not just the amount (so variable pricing is possible).
This map is a quick and dirty summary of the lesson you just finished. It's a quick way to get a refresher on the main points in the lesson. This is interactive so move your mouse over the topics.
Accessible Version (word document) [36]
When finished here, take the lesson 1 quiz.
It is not uncommon in the U.S. to assume that electricity will simply always be there when we need it (unless you have an unpaid bill!). The lights go on, the hairdryer blows (and heats), and the cell phone charges – all of it thanks to the people and processes behind the plug. Oh, and lots of fossil fuel and increasingly more renewable energy. For most of these processes that use heat, the steam generated is what is doing the work (spinning the generator). Please watch the following (2:08) video on steam generation.
[Dr. Mathews is standing at a table with a miniature steam engine.] Dr. Mathews: Well, I thought I would show you a very simple system for producing electricity. This is a little steam boiler. We are going to produce steam to power a steam piston that is going to reciprocate, spin the flywheel, and that is going to produce an electric current. That is what we are starting to talk about today. Electricity and the production of electricity from mostly steam. Then, we will start talking about other renewable energy types. But the bottom line is, what we are trying to do is spin a generator quite quickly to produce electricity.
This lesson is about all the things that happen before your electricity gets to you - how it is generated. These processes are connected to efficiency, conservation, and pollution (emissions).
Your success in lessons 02 will be based on mastering the following objectives;
Enjoy your trip "Behind the Plug" in Lessons 2 and 3 (remewables)!
The need for steam power was not initially to move people, goods, or services, but to pump water! Much of coal mining in the UK was deep underground mining where flooding is an issue. Thus, to extract more coal, the mines needed to continually pump water. This required a lot of work (work and energy are interchangeable, same units, so this means pumping required lots of energy [in a short amount of time—lots of POWER.) This was one of the first uses of the steam engine. The coal was also the fuel. We will see later that coal is a concentrated energy source that produces a lot of heat (high calorific value) so we can produce lots of steam and do more work with a small mass of coal. This was all happening in my "old" country, England, in the mid-1700s. The presence of coal and the engineers allowed the UK to pioneer the transformation from an agricultural society to that of an industrial society. The steam engine was used to turn looms (used in cloth manufacturing), pump water, turn belts, stir beer, and carry hops up to the upper floors of breweries. This revolution altered the distribution of the populace, enabled mass production, and created the intricate network of communications (road, rail, and canals) so that goods could be moved to different markets.
We will see that most of our electricity is generated from steam. The generator was around in early 1831, but it was not until later in the century (1873) that a practical device was developed. Now, steam engines could turn a generator and produce electric power. By 1936, electric wires had produced a grid that sent electricity throughout Great Britain. We don't even notice the miles of wires that follow the roads and branch off into our houses; it is part of the scenery.
The following (0:41) video gives you the basics of electric power production with steam.
[Dr. Mathews is sitting at a table and we hear a steam engine in the background.] Dr. Mathews: The industrial revolution was powered by coal and steam. I have a little engine here. It's using a solid fuel to produce steam from water. We have it turning a little steam piston and we can use this to make work. I have certainly been to breweries, for example, where they use this type of technology to move the grain up into the beginning of the brewery and everything else would be gravity fed from there. If you were a Ludite (persons opposed to technology), this is what you hated. Because this is what took the jobs away from the people and started the industrial revolution in England in the 17th century - in the 18th century, sorry. Marvelous! [Video ends with Dr. Mathews smiling at the camera.]
Lesson 2 is really all about the following relationships;
Imagine you have a flooded basement and you go to buy a pump. What you care about is the power of the pump. Either way, the same amount of energy is going to be used moving the water up and out of the basement, but the pump that will do it in a couple of hours has more power than the pump that will take the weekend to do the same amount of work. In essence, you need a pump with more horsepower. A lawnmower may have 5 hp, a garage door opener, 1/2 hp. If I swapped the engines, my garage door would fly open, but my lawn would require a long time to be cut with my now underpowered lawnmower. Much of the rest of the lecture is how we can generate electricity, lots of it and quickly, because, as you now know, we have a huge appetite for electricity (power) and energy in general.
One last thing to keep in mind:
When we generate energy, most of the approaches will also generate some pollution. Our leading contributors in the U.S. to electricity are natural gas, then coal, then nuclear. Even though crude oil is a fossil fuel it is mostly used in transportation. Note that crude oil is an insignificant contribution to electricity generation.
Natural gas combustion is currently the leading source of electricity in the U.S. at 38%. This is a remarkable change given it was the third leading fuel (behind coal and nuclear) in 1990.
There was a time when natural gas was worth practically nothing. In a single month, the Saudis would flare (burn-off) more than enough natural gas to run Europe for a whole year! Now, however, natural gas is prized and has significant use in home heating and electricity generation due to its current low cost due in part to improvements in our ability to extract natural gas from shale such as the Marcellus Shale deposit that is the largest gas play in the United States. Thus, in the U.S. we have abundant and cheap natural gas. In Europe, and Japan however natural gas is much more expensive.
The rise in popularity is somewhat influenced by the environmental issues of the other fossil fuels but is mostly influenced by price. While natural gas combustion is NOT pollution-free, it is much cleaner than coal or fuel oil when producing the same quantity of electricity.
Natural gas takes advantage of a technology that you might be familiar with: The turbofan engine on a plane, which is a type of gas turbine. The term gas refers to its state, not an abbreviation for gasoline. The secret to its success is in the compression of the air and the injection of already compressed natural gas. This mixture is then combusted producing the various (hot) products of combustion, which pass through the turbine vanes spinning the turbine like a windmill on a very, very windy day (it is actually much much faster). The turbine is connected to a generator that produces electricity. Watch this 2:39 minute video to see how a gas turbine works. We can also add a gas turbine to an existing steam turbine for a combined cycle system and achieve much higher overall efficiencies.
Air; a lot of gaseous molecules floating all around us. It's great for breathing and it turns out it's great for getting lights turned on. That's because air along with abundant natural gas or other fuels are the ingredients that combine in a gas turbine to spin the generator that produces electric current. If you follow the electricity you use at home or work back through the power lines to your local power plant, you'll see that the process most likely starts with the work of the gas turbine-- the very heart of the power plant.
First, air is drawn in through one end of the turbine, in the compressor section of the turbine all those air molecules are squeezed together, similar to a bicycle pump squeezing air into a tire. As the air is squeezed it gets hotter and the pressure increases. Next, fuel is injected into the combustor where it mixes with a hot compressed air and is burned. This is chemical energy at work. Essentially, this is what happens in your family car's engine but at about twenty-nine hundred times more horsepower. Actually, it's exactly like the turbine engines on jet airplanes, the hot gas created from the ignited mixture moves through the turbine blades forcing them to spin at more than 3000 rpms. Chemical energy has now been converted into mechanical energy.
The turbine then captures energy from the expanding gas which causes the drive shaft -- which is connected to the generator --to rotate. That generator has a large magnet surrounded by coils of copper wire when that magnet gets rotating fast, it creates a powerful magnetic field that lines up electrons around the coils and causes them to move. The rotating mechanical energy has now been converted into electrical energy because, the movement of electrons through a wire is electricity. In what's called a combined cycle power plant the gas turbine can be used in combination with a steam turbine to generate 50 percent more power. The hot exhaust generated from the gas turbine is used to create steam at a boiler which then spins the steam turbine blades with their own drive shaft that turns the generator. What you end up with is the most efficient system for converting fuel into energy and that's your GE gas turbine 101.
The General Electric Site [39] lists the key steps as:
The gas turbine can be used in combination with a steam turbine—in a combined-cycle power plant—to create power extremely efficiently.
Air-fuel mixture ignites.
Hot gas spins turbine blades.
Spinning blades turn the drive shaft.
Turbine rotation powers the generator.
Generator magnet causes electrons to move and creates electricity.
The key step in this process is the compression step, "The gas turbine compresses air and mixes it with fuel that is then burned at extremely high temperatures, creating a hot gas". This one step is the reason we can get more energy out of the combustion process. This makes natural gas the most efficient fossil fuel for producing electricity through the combustion process. Another reason for the higher efficiency is the higher temperature of the combustion process. Recall that we obtain energy through the combustion process of:
C + O CO
CO + 1/2 O2 CO2
and H2 +1/2O2 H2O
If I add all these steps together I get the overall equation:
CH4 + O2 CO2 + H2O
Natural gas has the greatest hydrogen to carbon (H/C) ratio of all the fossil fuels (4 hydrogen atoms per 1 carbon atom). As you obtain energy from the hydrogen steps and the carbon step, the temperature will be higher. Thus, the system will be more efficient.
The problem with heat engines such as this (a heat engine is something that produces heat to do work, usually through steam), is that have limited efficiency because of the thermodynamics of the system. Don't worry too much about the rest of this section, the bottom line is the overall efficiency of these stems is capped due to thermodynamics and if electricity from combustion is the goal — we are limited to below 57% efficient.
The maximum (Carnot) efficiency is 57%, so no heat engine will have a higher efficiency. Pulverized coal power plants will have efficiencies of 37% or so. Natural gas combustion is more efficient because the Thot is higher. All heat exhausts tend to be around the same temperature. To achieve 100% efficiency, we would need to extract all the heat as work and have the exhaust exit at 0 Kelvin (not actually possible) - a very cold -273 °C. This is the main bottleneck of all our thermal (heat engine) systems, from electricity generation to transportation. Higher efficiencies are possible for electricity generation if you do not go through the thermal step (which hydroelectric or fuel cells do not).
There are a couple of other uses for the gas turbine. For example, instead of using the rapidly rotating turbine to turn a generator, you can use the thrust to power your plane, or the rotating action to lift a helicopter, or even power the 2-ton M1 tank.
Something to remember: the equations above forget one very important component, nitrogen! As we use air (which is free) for our combustion medium rather than oxygen (which is expensive) the correct equation should be:
CH4 + 2O2 + N2→ CO2 + 2H2O + N2
This is just like the bit in the movie that makes no sense and seems to be extraneous information, but, is important in the plot later on.
Compared to other fossil fuels, natural gas is cheaper, burns cleaner, making it more environmentally friendly, and is safer and easier to store. And the U.S. has a plentiful supply of natural gas and new ways to extract it.
While plentiful, natural gas is not a renewable energy source and produces greenhouse gasses. It must also be handled with care due to it's combustible nature. The fracking process also causes concerns for water quality. We cover that and natural gas extraction in lesson 04 and 07.
Electricity generation is not the only use for coal, but it is the dominant use both worldwide and in the US. The concept is simple; through the process of combustion, the trapped chemical energy from the coal produces heat, which we can change into electricity, which we then use to do work. Sounds simple right? Well, it can be, but it can also be a complex junction of engineering, chemistry, and environmental chemistry. Coal was the traditional fuel of choice for electricty generation in the U.S. supplying ~50% in the 1990's. It has since declined to ~25%. Ensure you know why (has already been revealed in this lesson).
Coal is stockpiled into great piles; this is the supply of the coal so the power plant (which I might also refer to as a utility site) can operate even if there are transport problems (rail strike), supply problems (miners strikes, etc.) or weather-related issues (snow blocking tracks, etc.) The coal is in chunks of varying sizes. We do not want the particle size to be too small yet, or the coal could blow away, wasting the fuel and causing dust problems. They will often spray water over these coal piles to keep the dust down.
Coal is moved via a conveyor belt to the pulverizers where the coal is crushed into a fine dust (about 35 microns in size — a human hair is about 100 microns.) Particle size reduction helps to speed up the process of burning the coal particles. If the particle size is smaller, then there is more surface area for the same weight. Thus, the coal particle will burn quicker and the combustor can be smaller in size (so that all the coal has time to burn). So with these small-sized particles, a 10-story high combustor is about the right size.
Here is a very simple explanation of the process.
Coal-fired plants transform coal into electricity by pulverizing it and burning it in a furnace. The burning coal heats water in a boiler and turns it to steam. This steam, under tremendous pressure and at high temperature, provides the force to turn the turbine blades. The turbine spins an electromagnet inside copper coils in a generator and that produces the flow of electrons called electricity.
Now that the coal is in small pieces, it is blown into the burner where the air is mixed with the coal in controlled quantities and a complex mixing profile to attempt to reduce pollutant formation. There might be 12 or 24 burners in a boiler wall with the burner outlets poking through the water wall of the boiler, in an opening that even I, even the "chubby" Dr. Mathews could pass through (251 lbs currently—but I am on a diet!). There are different configurations of burners, but simply put, the inside of the boiler is very hot (1,500 °C) causing the coal to devolatilize, give off gases, which combust, then the remaining char particle combusts. The process produces heat, lots of heat (the reaction is exothermic.) So much heat, that the tubing you can see in the inside of the wall (the waterwall) is necessary to stop the boiler from melting! On the inside, the "water-wall," or the multitude of pipes for producing steam, are visible. The holes are where the burners poke through. These are very expensive (high capital cost) to build.
Water flows through the pipes and is transformed into steam. But not just any steam. By using high pressures and special materials (so they can withstand the high temperature), the steam can reach very high temperatures above 500 ° C and is known as superheated steam). We use the heat generated in the boiler to produce high-temperature high-pressure steam. Because of this, we can do lots of work to generate lots of electricity. That is achieved by the combination of a turbine converting this heat energy into kinetic energy (a rotating turbine), which in turn spins a generator for electricity production. The turbine has multiple vanes that act in a similar manner to a wind turbine blade but uses steam pressure to spin the turbine. We get more electricity by using larger turbines and faster rotation speeds. This is why a coal-fired or nuclear power plant can generate much more electricity than a single wind turbine
The combustion gases that leave the boiler are known as flue gases. The flue gas is, in some cases, cleaned (depending on the coal quality and regulations governing the plant) and sent out of the stack (chimney).
Here the airflow and heat movement inside the coal-fired boiler is shown. We will see later that through careful mixing of the coal and air that we can reduce NOx emissions (covered later). The heat rises and heats the water in the waterfall pipes to generate the high-temperature and high-pressure stram.
Back to the high-pressure steam: the steam is superheated to allow it to carry even more energy the pipes containing the steam are special metal alloys (mixtures of metals) to tolerate these harsh environments (and are thus expensive),
The steam passes through a turbine, which spins at a very fast rate. If you recall that energy cannot be created or destroyed, then you will realize that making the turbine spin in excess of 1,000 revolutions a minute takes some of the energy from the steam (but not all of the energy!)
To help the flow process, the low-temperature steam is cooled to transform it back into water. Water takes much less volume than steam, and so the resulting pressure drop helps pull the steam through the turbine. This takes a lot of cold water to do, and so most power plants are also near large bodies of water (lakes, rivers, etc). The water, which was steam, is recycled as it is high-quality water; the water vapor produced by cooling the steam with river water evaporates from the cooling towers (just water vapor, no pollution!)
The turbine then spins a generator, which is a coil of wires inside a field of magnets. This produces an alternating current of electricity, which is what we use in our houses to power most of our devices, and if you're reading this on your computer, then you can thank (in part) the system just described.
We have multiple stages to produce electricity. Each stage will have its own efficiency. The stage with the lowest efficiency is the weakest link in a chain - the system cannot be more efficient (or stronger) than that one component. Here, it is the inability to extract all of the energy from the steam that is responsible for the overall poor efficiency in the entire system. Add in multiple losses due to inefficiencies at other stages, and you have pulverized coal combustion producing electricity with an efficiency of about 37%.
We'll cover much more on energy efficiencies in later lessons but if we can be more efficient we will burn less coal and produce fewer emissions. The U.S. is now moving towards emission controls for greenhouse gases so any new coal-fired utilities will likely be required to have the same emissions as a natural gas-fired utility. As it is easier to use natural gas, it is expected that few new coal-fired plants will be constructed in the U.S., many older plants have or are closing, and natural gas use for electricity will increase along with wind and solar.
There are other approaches to the combustion of coal (not just pulverized coal combustion). In Pennsylvania, we have a coal mining legacy of abandoned culm/gob piles (a mixture of rock and rock containing coal that not of high enough quality for use — thus was rejected and piled at the mine site). One such man-made mountain is shown below. The term culm is used in the anthracite region of PA in the east, while the term gob pile is used in the bituminous regions that occupy the west of the state.
Watch the following 2:52 minute video "Circulating Fluidized Bed - CFB Boiler Process".
Sumitomo SHI FW is advancing steam generation technology with its state of the art circulating fluidized bed technology. Due to its fuel flexible, low-temperature burning process, CFB technology can utilize all types of coals, lignites, petroleum cokes, and carbon-neutral fuels like biomass and recycled waste to produce clean and economical power generation. It offers a major advantage over the limitations of conventional combustion-- the ability to burn the widest range of fuels.
Conventional coal technology requires the fuel to be finely ground and dried before entering the furnace. These steps are not needed for the CFB. Instead, the fuel is coarsely crushed and dropped into fuel chutes, which lead to ports in the lower section of the CFB's furnace. Unlike conventional boilers that burn the fuel in a massive high-temperature flame, CFB technology utilizes circulating hot solids to cleanly and efficiently burn the fuel in a flameless combustion process.
Its low uniform combustion temperature minimizes the formation of nitrogen oxides and allows the injection of limestone to capture acid gases as the fuel burns giving this CFB the lowest furnace emissions. Since the fuel's ash doesn't melt, heat transfer surfaces stay clean, allowing the hot solids to conduct their heat efficiently throughout the entire boiler, while fouling and corrosion are minimized. The payoff-- low plant emissions, low maintenance, and high plant reliability.
To achieve very high combustion efficiency for all fuels, the solid particles in the furnace are collected by steam-cooled, solid separators which recycle most of them back to the furnace. Before re-entering the furnace, the particles pass through a high-performance INTREX heat exchanger where steam coils are submerged in a bubbling bed of hot solids to efficiently produce high temperature superheat steam.
To further reduce plant operating costs and emissions, our CFBs can utilize vertical tube supercritical steam technology to achieve the highest plant efficiency. And for full capture of greenhouse gas emissions, we offer Flexi-Burn CFB technology, which can produce a CO2 rich flue gas for beneficial use by the oil, agricultural, chemical, and construction sectors. circulating fluidized bed technology is an important part of the solution to meet the world's energy needs while conserving natural resources and preserving our environment. Visit us at shi-fw.com for more information on our exciting technology.
After the coal has been separated from the rock the coal can be combusted but we use a different approach for the combustion process. This video shows the process of coal combustion via a circulating fluidized bed, showing the heat exchange to produce high-temperature steam, the circulation process for the coal char, with SO2 capture, and electricity production. In some locations, the hot water from the turbine is also used by local municipalities (such as for prisons, etc.) When this occurs it is called co-generation.
Circulating Fluidized Bed combustion is another method of burning coal that uses existing technology to produce electricity with very low emissions of both Nitrogen Oxide (NOx) and Sulphur Oxide (SO2) both of which contribute to the acid deposition challenges. Note: the fuel need not be coal but we will use coal for this discussion since we are in a lesson about electricity generation from fossil fuels. Fuel flexibility is one of the reasons that this boiler configuration is attractive, but most PA fluidized beds tend to be in the anthracite region where there is abundant and FREE fuel: culm piles (or so-called "gob" piles in Western PA). Culm piles are the waste material left behind from the mining process (mostly rock but some coal too). Fluidized Bed combustion is a way to reprocess this waste. They burn a much larger particle size than pulverized coal combustion (mm in size or larger), at a much lower temperature, over a longer period of time. They also have an in situ (in place) mechanism to capture the SO2 that would otherwise contribute to acid deposition. So here is how it works:
These "man-made mountains" of reject coal actually contain a significant quantity of coal. By removing the culm pile, producing electricity, there are employment, taxation, and cleaning open-pit operations (more on that when coal mining is discussed) opportunities.
The various stages are shown in this interactive figure (click on an asterisk for more information). Start with coal and work your way through the diagram in a counterclockwise direction.
Diagram of an Atmospheric Circulating Fluidized Bed Boiler.
Coal and Limestone are fed into the combustion chamber. The combustion chamber has air intake feeds and a center partition. Ash waste exit the combustion chamber at the bottom and are disposed of. Products enter the two attached cyclones at the top and then head to the heat exchanger. From the heat exchanger, the products enter fabric filters. Fly ash heads to disposal and flue gas exits via the stack.
Steam is a byproduct of both the combustion chamber and the heat exchanger. This is used to power a steam turbine which powers a generator and produces electricity. Excess steam is returned to the heat exchanger or to the boiler as feedwater.
Additional information:
Once the coal is cleaned to reject the associated rock, it is crushed and the relatively large pieces of coal are combusted in the presence of limestone. By suspending the particles with air flowing from underneath, enables the coal to be combusted slowly, the ash that forms can be rejected. The lime is formed from the added limestone (CaCO3), the heat causes calcination which is the formation of lime (CaO) + carbon dioxide gas (CO2). This combustion approach gives the coal a long residence time in the bed, allowing lower temperature combustion (thus less NOx), and the S is not emitted into the atmosphere because it is captured in situ (in place) by the lime (the gas forms a sold coating on the lime particle).
CaO + SO2 + 1/2 O2 --> CaSO4 (gypsum)
The lime/gypsum is a solid that can be used to fill in the old strip mining holes to restore the damage from old abandoned mines. Unlike the output from the scrubbers - described later, this gypsum is not pure enough to be used as a wallboard material (it is just a coating over the lime particle). More on this when we discuss acid deposition solutions in unit 3.
Nuclear power provides ~20% of the US electricity supply. To understand how it works, we need to first understand the nucleus of an atom.
We tend to think of atoms as solid balls linked together with chemical bonds forming molecules. The reality is that the "hard" shell that represents an atom is a representation of the electrons that are whizzing around the centrally placed nucleus. The "solid" ball is a poor representation; instead, think of a ping-pong ball. Most of the ball is empty; in the case of an atom, the shell(s) (mass of electrons) does not contribute much to the mass, as electrons are very low in mass. The bulk of the weight is in the nucleus where the proton(s) and neutron(s) reside. These each have a mass of 1 unified atomic mass units (also called Dalton). So, hydrogen, the simplest atom has 1 proton and 1 electron. It is the number of protons that determines the element, so 1 proton is hydrogen represented as 1H. If there is also a neutron, then the element is still hydrogen, but it is a different isomer. We call these deuterium atoms 2H or D, and if we produce water from it (D2O rather than H2O) we have "heavy water" (the two hydrogens being replaced with the heavier mass deuterium atoms).
Atom/Isotope | Half-Life |
---|---|
Uranium 235 (235U) | 0.7 x 109 YEARS |
Plutonium | 23,924,000 YEARS |
Radon 222 | 3.8 days |
Polonium 218 | 3 min |
There are many elements that are radioactive. For some, only certain isotopes are radionuclide (they are radioactive). However, some will have very long half-lives; others decay very quickly. During the decay, the nucleus splits into two or more atoms producing heat (the kinetic energy of these new atoms) and neutrons to continue the reaction. Given the long half-life of 235U, we can't wait for natural decay for electricity production. Instead, we induce the splitting of the atoms with a neutron. Basically, when the 235U (uranium) is induced into decay via capturing a neutron, the atom breaks apart violently, producing 2 fragments that are the new atoms and several neutrons. Thus, when at the critical state, 1 neutron is allowed to induce another 235U to decay. To increase the probability of this occurring the moderator has the role of slowing the neutrons down. As all of the fragments are moving quickly; they have lots of kinetic energy, or in the case of atoms and molecules we can say they have a high temperature. Thus, we can create steam, as discussed in the video, to turn a turbine (and spin a generator). If you wanted less fission, the control rods can be lowered — absorbing the neutrons and controlling or stopping the heat and thus the electricity produced.
Watch the following video (beginning at minute 1:30) to learn how nuclear energy creates electricity. What you watch here is fair game for the exam.
MR. ANDERSON: Hi. It's Mr. Anderson, and this is AP Environmental Sciences video 25. It's on nuclear energy. You're probably familiar with the Richter scale. It's a log scale by which we measure the size of earthquakes. But you're not familiar with the INE scale, or the International Nuclear Event Scale. It's also a log scale, and we use it to measure the size of nuclear accidents. We've only hit 7 twice.
The first time was in 1986 in Chernobyl. We had a collapse and a meltdown of the reactor. 31 people died from exposure to radiation. In 2011 in Fukushima, we also hit a level 7. We had three other reactors meltdown after an earthquake and tsunami. In the US, the highest we've ever gone is a level 5 at Three Mile Island. It released a little bit of radioactive material into the surrounding area. But it scared people. These accidents scare people, and radiation scares people because we can't see it.
And so the amount of energy we're getting from nuclear reactors has remained static for decades, but it's starting to be revisited again. And the reason why is there's also something in the environment that is scary, and it's also invisible. And that's carbon dioxide. If we look at the amount of carbon dioxide being produced by nuclear power plants, it's on the level of the same as wind generation or hydropower. If we compare that to gas and oil and coal, there's way more carbon dioxide being created. So new technology and a decrease in carbon emissions could see a resurgence of nuclear energy.
Where does the energy come from? It comes from the fusion of radioactive material, generally uranium-235. So as it decays, it breaks down into two fragments-- barium and krypton. And as it does that, it gives off energy, and it gives off neutrons that can trigger more fission and more radioactive 235. So the way this is controlled, unlike in a weapon, it's controlled in a reactor. Most of the reactors in play right now are light water reactors or normal water reactors.
What you do is you put fuel rods inside it. And as they decay, it produces a little bit of energy. And that energy inside the water heats it up. And we can use it to generate steam and then generate electricity. Now when it melts down, this goes out of control, and we get a release of that radiation into the environment. And so by having it in water, we can contain some of that energy. And we can also use control rods. These are actually going to take in some of those neutrons. And by lowering them between the fuel rods, we can slow down the reactor.
Now the disadvantages are pretty apparent. Nuclear waste is going to be created, and it can be around for thousands and thousands of years. So we have to keep track of that. Each of the radioactive materials has a different half-life, but it's going to be on the order of thousands of years. And also we have these accidents where we can have explosions, malfunctions, and it releases that radiation into the environment and can cause things like thyroid cancer.
Why do we still have it? Well, the advantage is that it creates a huge amount of energy. And it can do that without increasing the amount of carbon emissions in the environment. So if we look at uranium-235, now we're looking just at the nucleus. And so we're looking at the protons and the neutrons. And so if we were to hit one of those uranium atoms with a neutron, what it'll do is it'll break in half. It breaks apart into these two fragments. And as it does that, it releases a certain amount of energy. You can see it's also liberating three of these neutrons. And each of those have the potential to hit another uranium-235, and we can break it down.
So it's not an out of control chain reaction like this that we might see in a nuclear bomb, but it goes slow over time. And so if we look at what those fuel rods are like, most of the uranium is actually going to be uranium-238. A few of it is uranium-235. And so as those neutrons are given off, by having it in water, we can absorb some of that energy, and we can control that radiation. And also, we can lower these control rods. They absorb the neutrons, and so we can slow it down.
So if we look at a typical light water reactor, we're going to have the fuel rods and the control rods in the core. We're then going to heat up a fluid. And that fluid is going to be in a closed system. So as it moves through these pipes, it returns back where it was. But it's bringing with it a huge amount of heat. Now that heat moves into a separate loop. And so in this loop, what we're doing is we're heating up the water. It's forming steam up at the top. And then that steam is moving through a generator, so we're generating electricity.
And then finally, we still have a lot of heat right here. So before we pump it back in, we have to get rid of some of that heat. And so we're going to do that by pumping the water and another loop into a cooling pond. And so as long as we have energy contained within those fuel rods, we can generate electricity. But what happens when we decay too much of that uranium-235? Now it becomes waste. It's still radioactive, but it's not generating enough electricity for the plant to go. And so now we've generated waste. So that's one form of nuclear waste.
But we're also generating a little bit of heat over here into the environment as well. And so how do we deal with that waste? Well, how do we deal with the fuel rods? We're going to put him in a pool. And as we put them in the pool, we're going to absorb some of that energy here. But eventually, we're going to have to put it in some kind of a container. And a lot of these are on these concrete slabs. And we've got that nuclear waste contained inside there. There's no real long-range plan of what we're going to do with his nuclear waste. And it's going to be a problem that we'll have to deal with generations down the line.
If we look at how long this could occur, you have to understand what a half-life is. A half-life is going to be the amount of time it takes for half of the material to decay or to break apart. And so if we look at time 0, let's say the half-life is one year, at time 0, we'd have 100% of the radioactive material. At time 1, we would have 50% of it. In other words, half of it would have decayed. In another year, it would be half of that and a half of that and a half of that and a half of that.
And so in an AP Environmental Science class, you should be able to calculate the half-life. And let me give you a problem. Let's say radium has a half-life of 1,500 years. How long will it take for 250 kilograms of the radium to decay down to less than 10 kilograms? And so we're saying the mass of radium at the beginning is 250 kilograms at time 0. And so in one half-life, in other words, in 1,500 years, we would have decayed half of it down to 125. In another 1,500 years, we'd be down to 62.5. And you can just keep doing this. And you can see at 7,500 years, we're less than 10 kilograms left. But you can see a lot of that is still going to be radioactive.
Now what happens in accidents, something happens where we're not able to contain this core. And so if we look at Chernobyl, they were testing the reactor, and it got out of control. It heated. We have a melting or an explosion that actually collapsed the roof and released a lot of radiation. If we're looking at Fukushima, it's like three levels of protection that failed. We have an earthquake, but we also have this giant tsunami. And if we're looking at Three Mile Island, it was a problem with a valve but also a problem with user error as well.
And so all of these, for the most part, are human error, either we had a mistake at the reactor or had a mistake in the design. And what it does is it releases some of this radioactive material into the environment. So, for example, radioactive iodine can cause thyroid cancer. So we eat it in our food. It causes cancer years down the line. And we're going to see this-- wherever there's a nuclear accident, we're going to have increases in thyroid cancer after that.
So if we look at these accidents, so this is at-- here's Three Mile Island, here's Chernobyl. So we had the heyday of nuclear reactor creation during this oil crisis. But then after these accidents, you can see the amount of reactors that we have has remained static. And you can say even though we could produce this amount of energy, we're producing less of that. And the reason has to do with this fear of radiation and the fear of accidents as well.
And so what's the future hold for nuclear power? Well, they're going to be increases in new technology. Thorium reactors are going to be working much better than uranium, light water reactors. And we can have these third-generation reactors where we can actually reuse some of that waste. And then finally, we have to reduce carbon emissions, and nuclear energy is going to be part of that discussion.
So could you pause the video and fill in the blanks? Let me do that for you. Nuclear energy is the fusion of something like uranium-235. We break it apart into fragments. We also get energy and some neutrons that can cause fission in other atoms. We've got the fuel rods. That's where the radioactive material is, but we also have these control rods. Disadvantages, nuclear waste. It takes a long time due to the half-life of these radioactive materials for the waste to go away.
We can have accidents that increase the amount of cancer. Thyroid cancer is an example of that. But the advantages, again, nuclear power can help us reduce the amount of carbon dioxide in the environment, reduce global warming. And that's why it's being revisited. And I hope that was helpful.
Below is a static representation of a nuclear power plant. The caption provides a short explanation.
There are two primary advantages of nuclear energy: low cost (once the plant is constructed) and no greenhouse gas emissions - unlike many other major electricity generation sites!
Nuclear Power is quite controversial and comes with a number of concerns.
We currently have 96 reactors in the US producing electricity in 56 nuclear power plants in 29 states, far more reactors than any other single country! The oldest one running is the same age as I am (~50'ish)! They are licensed for 40 years with a 20-year extension possible. As most were built in the 1970s and 1980s, soon we will be looking at dismantling a large number of nuclear reactors. Cheap natural gas is accelerating the time frame to decommissioning nuclear plants.
The figure below shows the trend of our nuclear contribution. Given the age of the existing reactors, we can expect a decline in the number of reactors in the next decade. A good question is; Will we build new ones? In an era of climate change expectations, nuclear is an excellent means to produce electricity without greenhouse gases. However, after Fukushima (earthquake and resulting Tsunami in Japan), this event stopped new nuclear construction in many nations with some moving away from nuclear power completely. The few "new" nuclear reactors have been in construction for a long time due to many delays. One of the large advantages of nuclear power is no greenhouse gas emissions. So closing down nuclear utility sites after ~2025 will cause an increase in greenhouse gas emissions if we replace nuclear power with power produced by fossil fuels (such as natural gas). We do have one nuclear reactor activated in 2016 in Tennesee, it was the first new plant in the new century with two more under construction in Georgia expected to be completed in the 2020s. However, 17 nuclear reactors have been closed and are being decommissioned. So, nuclear power is likely at its peak production of electricity in the U.S.
Many nations are moving away from nuclear energy (despite the lack of greenhouse gas emissions) and are in the process of phasing out or reduce nuclear power.
This map is a quick and dirty summary of the lesson you just finished. It's a quick way to get a refresher on the main points in the lesson. This is interactive so move your mouse over the topics. Pay particular attention to the sections on coal, natural gas, and nuclear. The rest of the items will be covered in Lesson 3.
Accessible Version (word document) [52]
When finished here, take the lesson quiz.
We have just examined electricity generation from fossil fuels and nuclear power. Now we expand into the renewable elecricity sources.
Hydroelectric is one of the leading electricity sources for renewable energy, providing 7% of the US total electricity supply.
Renewable water power has been used for years to grind corn and grains into flour or to pump water. With hydropower, we convert stored potential energy into kinetic energy to do work or to generate electricity.
Potential Energy PE = mgh
M is mass
G is the acceleration due to gravity (~10 m/s2)
H is the height above a reference point
Imagine carrying a sack of potatoes up the stairs of a warehouse. Two things influence how much work you will have to do; the mass of the sack of potatoes, and the number of floors (the height) that you will have to carry the potatoes.
Our potato example would look like this in a formula;
To move a 60 kg sack 5 meters above the ground level becomes:
60 (kg) x 10 (meters per second per second) x 5 (meters)
= 3,000 kg m2s2
= 3,000 Joules (J) or
= 3 kJ
If you recall the energy laws, energy cannot be created or destroyed, and so, if we drop the sack of potatoes, we will obtain the same amount of energy back (but in various forms). Thus, potential energy is stored energy. Hydroelectric energy works in the same way. We use the stored energy in water to produce electricity by flowing the water through a turbine (to spin a generator as usual). The water flows because of the influence of gravity, and that it is above the reference height.
Hydroelectric energy is renewable because the water that flows through the turbine to create electricity is replaced naturally by the water cycle. The sun (solar energy) evaporates water from the seas and lakes; some of the water will form clouds high in the atmosphere that will drift over land, and the water will fall back to earth in some form of precipitation (hail, fog, snow, or rain). The water flows into rivers and streams and the kinetic energy can be used for useful work. In the case of the large hydroelectric operations, the rivers have been dammed to generate large lakes. The dam holds the water back and raises the level of the water above the reference level (the bottom of the dam). In the U.S. we have already used many of the primary sites for large-scale hydroelectric production and those that are left are unlikely to be dammed due to the damage it inflicts on the ecosystem. Hydroelectric power (large scale) was one of the cheapest of the renewable options and a source for a significant quantity of electricity in those regions where it could be employed at scale. For a long time, hydroelectricity was the leading renewable electricity source but has recently been surpassed by wind power in the U.S.
China is the leading nation for electricity production and has been increasing its generation capacity with very large-scale additions such as the Three Gorges Dam [57] (almost twice the size of other large-scale sites). The U.S. hydroelectric production has however remained steady for decades.
The energy we are trying to capture is kinetic energy:
Kinetic Energy = 1/2 mv2
Unfortunately, to change all the kinetic energy into electricity would require the water to have no velocity whilst exiting the turbine. This is impractical, as we do not transform all the kinetic energy into electrical energy. We can obtain more energy by increasing the flow rate of the water (increasing the mass of water) and by increasing the velocity of the water (increasing the height of the dam increases the water pressure and thus increases the velocity and the mass). PLEASE SEE THE HTML SOURCE BELOW
See the visualizations provided by the "Energy.gov" website, and their section on hydroelectric power [58]. Give it a look with the goal of understanding how hydroelectric power produces electricity.
The worlds' largest dam is the Three Gorges Dam. Producing 20,000 MW (for scale the Hoover Dam, pictured here, generates about 1,400 MW). The river navigation and flood control will also improve because of the dam (flooding has killed 300,000 last century). Hydroelectricity will provide clean electricity for the rapidly growing industries of eastern and central China. This is desirable because most of China's electricity comes from coal power plants close to the cities—lots of polluted air. Of course, such a large project has rather large costs as well; one million-plus people will have to be relocated, fish migration will be stopped, and there may be increased threats to the survival of the Yangtze River dolphin, along with many other animal species. As is common with most issues of energy and the environment, however, there is plenty of disagreement over whether the dam is really the right thing for this country.
Some consider the hydroelectric industry as "mature" and that the technical and operational aspects of the industry have not changed in the past 60 years. Research is currently underway that concentrates on new concepts for the industry, and one project is testing new turbine designs. This project will hopefully recommend a final blade configuration that will allow safe passage of more than 98% of the fish that are directed through the turbine (I wouldn't want to be part of the 2%.) The US Department of Energy has identified more than 30 million kilowatts of untapped hydroelectric capacity that could be constructed with minimal environmental effects at EXISTING dams that do not have generating facilities at the present time, and also at EXISTING dams that are underutilized, and at a number of sites where dams do not presently exist. This research and planning activity suggests that hydroelectric power could continue to be an important part of the US energy picture for some time to come. In-river hydro is also an option (kinetic energy from flowing water WITHOUT the dam). (See Ocean Energy Technologies [61] of D.O.E.)
Here is a good overview video (3:50 min) by the U.S. Department of Energy. It is a few years old so it still (now incorrectly) claims that hydroelectricity is the leading renewable energy source for U.S. electricity.
PRESENTER: People have been capturing the energy and moving water for thousands of years. And today, it's still a powerful resource that can generate clean, renewable, and affordable electricity. You see, we harness energy from flowing water and convert it to electricity. That's what we call hydroelectric power, or hydropower. Water flows from a higher elevation to a lower elevation. And a hydropower facility uses turbines and generators to convert this motion into electricity.
America has been using hydropower to generate electricity for more than 100 years now. And today, about 7% of all our electricity is generated from hydropower, making it the largest source of renewable power.
[MUSIC PLAYING]
So what makes hydropower renewable? It's simple, water. Water evaporates into clouds and recycles back to Earth as precipitation. The water cycle is constantly recharging, and can be used to produce electricity along the way. How does it work? Basically, there are several ways hydropower technologies can generate electricity. You may recognize dams, like this one. This technology is called an impoundment. The impoundment stores water in a reservoir. When the water is released, it flows through and spins a turbine, turning a generator that produces electricity.
Here's another technology. This is a diversion. It channels a portion of a river through a canal or pipe into a turbine and generator system. What's cool about this method is that it uses the natural flow of the river, and usually doesn't require a large dam.
And have a look at this. This is called pumped storage hydropower. Basically, it works like a huge battery. To charge the battery, water is pumped back up into a reservoir during periods of low energy use, often during the night when people are using fewer appliances. Then when people need more power during the day, the water can be released to produce electricity.
[MUSIC PLAYING]
As long as we've been capturing energy from water, you may think there's nothing new in hydropower technology. Think again. The Department of Energy is helping to upgrade older facilities by increasing the efficiency of the turbines and generators. Operators of neighboring hydropower facilities are also working together to optimize energy production across whole river systems, instead of each dam working alone. And we can add generators or retrofit dams that were built without power, like dams used to water crops or prevent floods.
Today, there are about 80,000 dams in the US. But less than 3% of these dams produce power. That means there's a big opportunity to generate more clean renewable power at dams we've already built.
New technology is also making hydropower even more environmentally-friendly. For example, researchers are reducing adverse impacts on fish with fish-friendly turbines. And fish ladders like these let them swim around dams.
Hydropower is an essential, reliable, and renewable source of clean energy with a rich history, and it's meeting substantial energy demands today. With new technologies, it will be even more efficient and have greater production capacity, powering US homes and businesses for centuries to come.
Wind power generated 7% of the electricity in the U.S. and is now the leading renewable energy source for electricity in the U.S. While wind power is one of the oldest forms of energy it has rapidly increased its contribution in the last decade. The wind blows because of uneven heating of the earth's surface, producing high and low pressure, and thus results in airflow (wind). It is a renewable energy because solar energy (heating the earth's surface) is renewable. Early windmills were used to grind grain or to pump water. When we generate electricity we use wind turbines (not wind mills).
Wind power is one of the fastest-growing sources of electricity. It is now the leading renewable energy source for electricity in the U.S. (surpassing hydroelectric power in 2018). The reason we were historically not utilizing wind is simple: fossil fuels were cheaper alternatives (and more reliable) for electricity generation. As the cost of wind-generated electricity has drastically declined over the last decade, wind-generated power has increased dramatically here and in many other nations with the potential for more improvements. That said, solar energy generation is becoming more desirable and is expected to be much of the renewable electricity increase in capacity.
Wind turbines come in different shapes and sizes. The vertical ones tend to be tall to take advantage of the higher wind velocities (more energy), the slower wind velocity at ground level is caused by friction or drag with the earth's surface. One of the tallest wind turbines constructed so far is in Hawaii; the blade is longer than a football field and is 20 stories tall. The blades are shaped so from the side, they are similar to an aircraft wing, with the other side of the blade (from the point of rotation) turned the other way. The blades "push" to produce the spinning rotation. This rotating motion turns gears that produce a much faster rotation within a small generator in the nacelle — producing electricity. The blades can pitch to capture more of the wind energy or to stop the blades when the wind velocities are too high.
We are transforming kinetic energy into electricity.
Recall that KE =1/2mv2
The mass of the wind can be increased by using a bigger blade to "catch" the wind (area of a circle is Pi times the radius squared, so doubling the radius quadruples the area), or having a higher velocity wind (because more air flows within the turbine diameter, but more importantly because the energy in wind is proportional to velocity cubed). Density changes in the air can also increase the kinetic energy of the wind and thus the mass will be greater (density = mass/volume). The density of air is lower than the density of water, so water with a density of one will have much more kinetic energy than the wind at the same conditions of flow! Also, our extraction efficiency is limited, because to transform all of the kinetic energy from the wind into electricity would require the wind to have zero velocity, which if it did the turbine would not turn! Thus, there is a maximum efficiency of 59% (Betz Law).
Watch the following 2:46 minute video about how a wind turbine generates electricity.
[MUSIC PLAYING]
PRESENTER: How does a wind turbine work? You've probably seen a wind farm. But do you know how wind force is converted into electrical energy? We are going to show you how a wind turbine works.
Each wind turbine has a wind vane at the top that indicates the wind direction. This allows the turbine to rotate on the tower and face the wind. The blades also rotate on their axis for maximum resistance. Wind force, that is the kinetic energy contained in moving air currents, spins the blades.
These are designed to fully capture its energy. They can be as long as 60 meters each and are made of very light and resistant materials for ease of movement. This is why they can produce energy even with very light winds, starting from about 11 kilometers per hour. With very strong winds, above 90 kilometers per hour, the blades are placed in the feathered position, and the turbines stop spinning for safety reasons.
[MUSIC PLAYING]
The blades are attached to the wind turbine through the HUB, which is coupled to the low-speed shaft. The low-speed shaft is given this name because it spins at the same speed of the blades, between 7 and 12 revolutions per minute. To produce electricity, it is necessary to increase the turning speed of the low-speed shaft. That is the mission of the gearbox, which raises the speed over 100 times and transfers it to the high-speed shaft.
The high-speed shaft, that rotates it up to 1,500 revolutions per minute, is connected to a generator. The generator converts the kinetic energy into electricity, a source of energy that is easier to transport and use. The electricity produced in the generator is conducted through the interior of the tower to the base. There, the transformer raises the voltage for transport inside the wind farm.
From each turbine, alternating current is sent to the substation to underground cables. Here, the voltage is increased again to feed it into the power grid and transport it to end consumers. This is how we use the wind to light cities, feed industries, schools, or hospitals, or operate our household appliances in a clean and sustainable way.
[MUSIC PLAYING]
Land Use
It requires a large plot of land to house enough wind turbines to make the wind farm and produce enough electricity. The land below the turbines can still be used for grazing or for crops. Unfortunately, land near population centers is expensive and it is impracticable to have less populated areas like North Dakota produce lots of wind power and ship it to the more populated areas of the U.S.
Intermittency and Low Capacity Factors
The wind does not blow all the time. Thus, you might be getting electricity at a time when it is not needed (we always try to use the cheapest electricity source). The capacity factor is a measure of how much electricity is generated in relation to the maximum quantity. For many wind turbines, this is ~34%.
Storage
Electricity storage is a challenge. Batteries are traditionally expensive, heavy, and not a good storage option but advances in this area are producing near-term viable options but they're not quite there yet (more on this later). Pumped storage is a viable but limited option, large-scale battery operations are also starting to emerge.
Noise Pollution
Wind farms are not the serene creaking and groaning of the old windmills. There is noise, which can be an issue if it is close to residences. Some might add that they are ugly too, but beauty is in the eye of the beholder.
Bat and Avian Issues
Birds seem to have the tendency of flying into the blades, which kills them! For bats, it is getting close to the low-pressure region (they dodge the blades) but then get the "bends" in the decompression zone of low pressure (similar to a deep-sea diver coming to the surface too fast). In some bat sensitive locations, they do not use the turbines in select evenings when the conditions are conducive to bat activity. Many of the avian and noise issues have been solved by going to longer blades, and improved locations (avoiding migration routes). While visiting several windmill farms I could not find a single dead bird. Bats tend to like to swarm the tallest object around and the largest number of kills occur on a single summer night. Some wind turbines may have to stop running on certain evenings in the summer season if there is a lot of bat activity.
Supply and Demand
In some cases, there is a mismatch between where the wind resource is located and where the electricity is needed (population centers). In locations such as Germany, the higher quality wind resource (higher wind speeds and higher capacity factors) is in the north while the population centers are in the south. Thus, new high voltage lines are needed to deliver the electricity, increasing the initial cost. Despite this, they are using more wind power 40% than many nations (however, they also have much higher electricity costs).
Spend a few minutes learning more about Wind Power via the US Dept. of Energy's website [63] on wind energy.
Also, note that part of the reason for the growth in electricity generation from wind is the lower cost allowed by using larger turbine sizes (source EWEA).
Many of the problems can be alleviated and higher energy generation can be generated using off shore wind farms. These have started to emerge as viable options and will start moving to deeper water.
Recall that we have already covered solar energy from the standpoint of home heating and water heating (passive and active solar heating). Solar energy is also responsible for nearly all the other renewable energy sources as well (solar energy drives the water cycle, creates wind, and is the energy source for biomass). Historically it has had a relatively low contribution to electricity generation in the U.S. That however is about to change. On this page we are concerned with solar energy being converted into electricity, whether directly via solar cells (photovoltaic) which is the majority of the contribution, or indirectly via heating some type of medium (thermal solar), which is then used to generate electricity from steam.
Solar cells generate 2% of the U.S. electricity supply. We can directly turn solar energy into electricity utilizing photovoltaic technology. Solar cells are also used in remote locations such as space, and in remote locations where there is not a connection to the electric grid, on RT 322 across PA to power some of the temporary signs (otherwise someone would have to come out and either recharge or replace the battery), on satellite wings, and many other locations. There is a wide range of efficiencies but ~20% is common for solar cells. Cheaper solar cells are less efficient. A dozen or so solar cells can either be placed on the roof (or close to home) or in solar farms where 1,000's of larger cells can be present.
The following 2 minute video does a great job showing how Photovoltaic (PV) panels convert solar energy into renewable electricity.
PRESENTER: All right, we all know that the sun's energy creates heat and light. But it can also be converted to make electricity-- and lots of it. One technology is called Solar Photovoltaics, or PV for short. You've probably seen PV panels around for years but recent advancements have greatly improved their efficiency and electrical output. Enough energy from the sun hits the Earth every hour to power the planet for an entire year.
Here's how it works. You see, sunlight is made up of tiny packets of energy called photons. These photons radiate out from the sun and about 93 million miles later, they collide with a semiconductor on a solar panel here on earth. It all happens at the speed of light. Take a closer look and you can see the panel is made up of several individual cells, each with a positive and a negative layer, which create an electric field. It works something like a battery.
So, the photons strike the cell, and their energy frees some electrons in the semiconductor material. The electrons create an electric current, which is harnessed by wires connected to the positive and negative sides of the cell. The electricity created is multiplied by the number of cells in each panel and the number of panels in each solar array.
Combined, a solar array can make a lot of electricity for your home or business. This rooftop solar array powers this home. And the array on top of this warehouse creates enough electricity for about 1,000 homes.
OK, there are some obvious advantages to solar PV technology. It produces clean energy. It has no emissions, no moving parts. It doesn't make any noise, and it doesn't need water or fossil fuels to produce power. And it can be located right where the power is needed, in the middle of nowhere. Or it can be tied into the power grid. Solar PV is growing fast, and it can play a big role in America's clean energy economy, anywhere the sun shines.
Another nice explanation of How Solar Photovoltaic Cells Work [66] can be found on the DOE's Office of Energy Efficiency & Renewable Energy website.
The advantage of using solar technology is no fuel costs, it is a renewable energy that is clean during operation (no air pollution or greenhouse gases) but obviously, energy is used in the creation of the panels, etc. Solar derived electricity had a limited contribution to the US energy profile until recently when prices became more competitive. Where solar panels had initially been most beneficial was in remote locations, where it would be expensive or impossible to link power lines. Falling production costs mean that we can not have large-scale solar farms using photovoltaic approaches. Tax credits also lower the overall cost of the systems.
The disadvantages of solar energy in general (for electricity generation) are the large plots of land required, and the inconvenience of those cloudy days (intermittency) and at night. Regional haze also reduces the amount of solar energy that reaches the surface so sunny locations like Florida become less economic because of the haze as other locations (we will see a map a little later on). Electricity storage is also an issue unless the photovoltaic can be hooked into the local electricity grid or large-scale battery storage. Some nations such as Germany, however, have managed to generate significant electricity with the photovoltaic approach often now being coupled to some storage solution such as large-scale batteries (or currently in Germany to coal-plants that can quickly generate electricity). Similar to wind turbines, solar panels also use rare earth elements — that are in limited supply.
Thermal solar relies on concentrating the solar resource. There are two options: reflective mirrors on a tower and parabolic collectors (troughs). For the concentrating tower solar sites many in the U.S. are in California (high electricity prices, and a very good solar resource). Spain also has a large number of these types of solar thermal plants.
The following 2:16 minute video explains how CSP works to produce electricity.
PRESENTER: OK. Take the natural heat from the sun. Reflect IT against a mirror. Focus all of that heat on one area. Send it through a power system. And you've got a renewable way of making electricity. It's called concentrating solar power OR CSP.
Now, there are many types of CSP technologies, towers, dishes, linear mirrors, and troughs. OK, have a look at this parabolic trough system. Parabolic troughs are large mirrors shaped like a giant U. These troughs are connected together in long lines and will track the sun throughout the day. When the sun's heat is reflected off the mirror, the curved shape sends most of that reflected heat onto a receiver.
The receiver tube is filled with the fluid, and it could be oil, molten salt, something that holds the heat well. Basically, this super hot liquid heats water in this thing called a heat exchanger. And the water turns to steam. Now the steam is sent off to a turbine, and from there it's business as usual inside a power plant.
A steam turbine spins a generator and the generator makes electricity. Once the fluid transfers its heat, it's recycled and used over and over. And the steam is also cooled, condensed, and recycled again and again. One big advantage of these trough systems is that the heated fluid can be stored and used later to keep making electricity when the sun isn't shining.
Sunny skies and hot temperatures make the southwest us an ideal place for these kinds of power plants. Many concentrated solar power plants could be built within the next several years. And a single plant can generate 250 megawatts or more, which is enough to power about 90,000 homes. That's a lot of electricity to meet America's power needs.
Another nice explanation of Concentrating Solar-Thermal Power [69] can be found on the DOE's Office of Energy Efficiency & Renewable Energy website.
The DOE says the following about the capacity for a large-scale plant. "At capacity, there is enough power for 150,000 homes. The facility covers more than 1000 acres, with over 1 million square meters of collector surface. The SEGS utilize parabolic trough collectors to focus the sun's energy on a pipe carrying a flow of heat transfer fluid (synthetic oil). The fluid flows to heat exchangers where the heat turns water into steam to drive conventional steam turbine generators, which produce electrical power."
In lesson 1, we discussed geothermal heat pumps as a method of producing home heating, cooling, and hot water by taking advantage of the solar energy captured by the first meter or so of the earth's surface. Here we are considering the energy that is contained within the earth, specifically the hot molten core for electricity generation (not home heating and cooling!!!!). The planet is comprised of a molten core surrounded by a crust. Unfortunately, the amount of energy coming to the surface of the earth from geothermal is small in most locations. Currently geothermal contributes 0.5% to the electricity generation in the U.S.
The following video 3:47 minute video. It provides an excellent overview of geothermal energy production.
You may have relaxed in a natural hot springs pool or seen the Old Faithful geyser blasting hot water into the air at Yellowstone National Park. But have you ever thought of where all that heat comes from? Well, it comes from deep beneath the surface of the Earth. And it's called geothermal energy. And we can use it to generate clean, renewable electricity.
OK, here's how geothermal works. Heat from the Earth's crust warms water that has seeped into underground reservoirs. In some places, when water becomes hot enough, it can break through the Earth's surface as steam or hot water. This usually happens where the Earth's crust or plates meet and shift. In the past, taking advantage of geothermal energy was limited to areas where hot water flowed near the surface. But as geothermal technologies advance, we can leverage even more of these natural renewable energy sources.
Engineers have developed a few different ways to produce power from geothermal wells drilled into the ground. Have a look at this. It's a dry steam geothermal power plant. And it's the most common type of geothermal technology used today. Underground steam flows directly to a turbine to drive a generator that produces electricity. Pretty straightforward.
Another geothermal technology is called a flash steam power plant. A pump pushes hot fluid into a tank at the surface where it cools. As it cools, the fluid flashes or quickly turns into vapor. The vapor then drives a turbine and powers a generator.
A binary cycle plant works differently. It uses two types of fluid. Hot fluid from underground heats a second fluid called a heat transfer fluid in a giant heat exchanger. The second fluid has a much lower boiling point than the first fluid. And so it flashes into vapor at a lower temperature. When the second fluid flashes, it spins a turbine that drives a generator.
The environmental benefits of this clean, round-the-clock, renewable energy source are substantial. Low emissions, small physical footprint, and minimal environmental impact. The few byproducts that can come up are often reinjected underground.
Geothermal energy can also help recycle wastewater. In California, wastewater from the city of Santa Rosa is injected into the ground to generate more geothermal energy. Some plants do produce solid waste. But that solid waste may contain minerals that we can remove and sell, which lowers the cost of this energy source.
The US Geological Survey estimates that untapped geothermal resources in the United States if developed could supply the equivalent of 10% of today's energy needs and cut our dependence on fossil fuels. In fact, electricity generated by geothermal energy already provides about 60% of the power along the Northern California coast. From The Golden Gate Bridge to the Oregon State line, geothermal energy-- helping to push America toward energy independence and a clean, renewable way to meet our growing energy demands.
Another nice explanation about Geothermal Basics [70] can be found on the DOE's Office of Energy Efficiency & Renewable Energy website.
Averaged over the earth's surface, the heat energy flow is 0.06 Watts per square meter (500 times less than the incoming solar energy flux). This is much smaller than incoming solar energy and so for most locations extracting geothermal energy (other than surface heat pump applications) will be too costly to drill down deep towards the core of the planet. In some locations, however, geothermal energy is far more concentrated and accessible. Locations such as Jellystone (oops, Yogi Bear slip), Yellowstone National Park's "Old Faithful" are recognizable and spectacular examples of geothermal activity.
As can be seen in the map below, certain locations have easy access to geothermal energy. Many of the island chains owe their existence to volcanic activity. Iceland, New Zealand and Hawaii have ample geothermal energy and use this renewable energy for the generation of electricity, home heating, hot water, etc. In the US, geothermal accounts for only about 0.4% of our electricity.
How the electricity is generated from geothermal follows the same principles as the techniques already covered in this course. In an open-loop system, water and steam are separated. The high temperature, high-pressure steam turns a turbine, that spins a generator, that produces electricity. The steam is cooled and the water injected back into the ground to ensure that the system is renewable. In closed-loop systems, water is injected into the ground in a pipe where heat exchange warms it up and returns it as steam or hot water. In a binary system, ammonia is used in place of water as the working fluid. Ammonia will be a liquid at normal conditions but can easily be converted into ammonia gas (it has a low boiling point). The ammonia is used to turn the turbine (this technique is also used in Ocean Thermal Energy Conversion (OTEC), more on that later). The advantage of this method is that it can be used when the thermal gradient is not as great. Most of the geothermal plants use the open-loop system.
Here is a domestic geothermal power plant located in California (one of the 18 plants operating within the Geysers geothermal field). Multiple wells were drilled to supply the steam to the power plants (some as deep as 3 km to reach the higher temperature water). This is a mature site with over 60-years of operation. It was approaching the end of life as the water resource had been depleted (and water is expensive in California) but has been extended by injecting wastewater. There are geothermal pools in the region but interestingly no actual geysers!
Biomass does not contribute very much to our electricity supply in the U.S. at only about 2%. However, agricultural and timber wastes are used to generate steam and heat for industries. As a source of energy, biomass offers a host of positive qualities; It is fairly plentiful, relatively inexpensive to use, and helps reduce agricultural waste problems. Most importantly, however, biomass is a renewable energy source, thanks to the carbon cycle and solar energy.
Solar energy is used by plants to generate energy in chemical form (glucose).
6CO2+6H2O + solar energy → C6H12O6+6O2
When plants die, this process simply works in reverse.
C6H12O6+6O2 → 6CO2+6H2O + energy
Walking through almost any forest is the best way to witness the decaying process in action. The ground is generally strewn with dead and decaying leaves, limbs, branches, and sometimes entire trees. If they did not decay, we would be faced with a serious dead-tree problem in our forests. Then, imagine the scope of this problem over millions of years. This helps illustrate the nature and value of the carbon cycle.
However, in Pennsylvania, about 320 million years ago (and even today), the forests did not decay. Instead, the trees fell into swamps (bogs) and were protected from the decay process. Eventually, these trees formed coal, and in the oceans, plankton and algae went through similar processes. There, the stored solar energy eventually formed oil (protection from oxygen at the bottom of the ocean, with sediment burial). Now as we use the fossil fuels (combustion), we release CO2 back into the atmosphere.
So, instead of allowing the biomass to rot naturally as explained above, we can harvest it and combust the biomass for home heating, industrial use, or electricity generation.
Let Dr. Mathews tell you the full story in the (:46) video below:
[Video opens with Dr. Mathews standing in front of a display of biomasses.] Dr. Mathews: Biomass, if it is an agricultural waste or even a plant deliberately grown for use in biomass, then we have an excellent source of free energy. We just have to harvest it; it is free solar energy being stored in the plant. The plant grows, and we can come and harvest it. And one of the other nice things about it is it's CO2 neutral. Even though when we combust it we produce carbon dioxide, when you grow the tree again, or we grow the plant again, or even livestock, that CO2 is stored back in that animal or that plant. And, really, there are 4 classifications behind me which we are going to look at. There are the grasses, there are the woods, there are the proteins, and there are the fats and lards. We are going to have a look at each one of those. [Video ends.]
Now that you've been introduced to the idea, you're ready for the details.
[Video opens with the caption: Biomass - Weeds and Grasses.] Dr. Mathews: This is switchgrass. [Dr. Mathews holds up a small bottle.] Dr. Mathews: Things like this are wonderful. They are more or fewer weeds but they are going to grow very quickly. And that is also desirable. You wouldn't want to have to plant an oak tree and wait 30 years before you could harvest it. But things like switchgrass are harvestable within 6 months. So you can get a couple of crops a year. And so anything like this that will grow quickly is possibly something that we use. [Video ends]
[Video opens with a caption: Biomass - Wood Products.] Dr. Mathews: Wood again is another one. [Dr. Mathews picks up a small bottle.] Dr. Mathews: This is a tree of heaven. It is again a very quickly growing small tree, but like a bush. It is somewhat of a problematic plant. It grows on the sides of the roads and some parts of the south they have a major weed status. But again, quickly growing, we can crush it up and fire it either by itself or we can add this, to say, a pulverized coal facility and burn perhaps up to 10 percent the material being this biomass, this wood. Doesn't have as much energy content as coal because it is not concentrated, it has a lot of oxygen. But it is still very useful. But remember one of the main advantages of the biomass is that it is CO2 neutral. And so you plant the seed, you grow the seed, you cut it down, and you burn it. Provided you go and replant the seed, you are going to keep that CO2 locked away. [Video ends showing 4 bottles of this woody biomass.]
[Video opens with a caption saying: Biomass - Oil, Grease, Animal Fat, and Lard.] Dr. Mathews: McDonald's grease, something else that you can use. It is a waste product; it was already been used to fry french fries or various other components in it. You are not going to use it anymore to fry food in, but it still has calorific value. Remember, the difference between vegetable oils for cooking and oils for combustion is very little. Is just about length, but we can still burn these things. [The camera pans past several bottles of oil.] Dr. Mathews: This is choice white grease, we have coconut, you can crush coconuts and extract their oil. That again is something you can use for cooking purposes and once you have fried things in it you can go ahead and use it for other things - combustion. [Dr. Mathews holds up a small bottle.] This is poultry fat. We kill an amazing number of chickens every year. Not much is wasted. This fat is something else that you can think of as a waste product; something else you would need to dispose of, or you can use it as a fuel. [Dr. Mathews puts that bottle down and picks up another one.] Dr. Mathews: Ah, pork. There is a saying that you use everything from the pig, including the squeal. [Sound of a pig plays in the background.] Dr. Mathews: Well that is pretty much true. In the old days you could use the pork fat to make candle. You could use the liquid fuel for lighting prior to kerosene. Now pork oils have a value. Lard has a value. But if, for say, we were looking at having lower cholesterol, and going with a non-fatty, non-high cholesterol fat, then the pork market might go away for lard. In which case it would have to be disposed of. It is a beautiful boiler fuel. We heat it up to melt it and turn it into a liquid, and inject it into our boilers. It has very low sulfur content. And so pollution really isn’t an issue and it burns very nicely. It isn't quite as nice as, or have as much energy content as fuel oil, but you just have to burn a little bit more. Again, if it ever came to a problem that we had to dispose of it, combustion is one way we could dispose of it very cleanly and get a useful product at the same time. [Video ends showing several bottles of the fats, greases, and lards.]
[Video opens with a caption saying: Biomass - Animal By-Products.] Dr. Mathews: Here are some other rather strange biomasses. [Dr. Mathews picks up 2 containers.] Dr. Mathews: This is feather meal. Again the chickens, we have no use for the feathers. If you grind them and extract them down this can be fed to other animals. Although with the Bovine Spongiform Encephalopathy scare, mad cow disease to you and I, we have gone away from feeding some of these other animal products to animals. And because I ate beef in England for a couple of years before coming here, I can't even give blood anymore because they are frightened that I have mad cow disease. [A caption reads: ...mad professor maybe...] Dr. Mathews: They might be right. Again, pork meal. It is essentially animal proteins that we can extract. There is still a lot of energy in these so we can go ahead and burn them. Manure would be something else we could use. And we have certainly looked into chicken litter (which is really chicken poop) and other manure. Obviously, in Africa they use certain manure for biomass applications and so we can certainly do the same things here if we had the desire to. [Video ends]
Biomass does not contribute as much to electricity as it does to industrial heat generation where industries that produce a combustible biomass waste product and require heat use the waste. Paper mills are a good example of this. The whole tree does not go into the paper manufacturing; bark, leaves, and small branches are combusted to generate the heat to drive off the water from the water/cellulose slurry.
When we discussed lighting, sperm whale oil was the fuel of choice for some of our ancestors. Candles would have also been produced from animal fat (pig fat worked well), and if the need arose, we could combust fats (currently pig fat is too valuable to burn; it is used in frying potato chips.)
The bottom line: Expect to see biomass being integrated into existing utilities that burn other fuels, rather than the creation of large biomass-only utilities. It is already a requirement in many states that renewable energy contributes to electricity generation. (This is known as the renewable portfolio standards.) In Pennsylvania, this can include photovoltaic energy, solar thermal energy, wind, low-impact hydro, geothermal, biomass, biologically-derived methane gas, coal-mine methane, coal-waste (those culm/gob piles), and from using fuel cells.
The water in the ocean is constantly moving due to waves (from the wind) and tides (mostly from the moon). This movement can be turned into energy in a number of different ways which we will discuss here. However, there are only a few locations where the electricity-generated is currently significant.
The tides are associated with the gravitational pull from the moon (and to a lesser extent the sun). The moon rotates around the earth on a lunar cycle that is close to a calendar month. The waxing and the waning of the moon are associated with the sunlight being reflected from the surface of the moon (the moon does not generate light so the "Dark Side of the Moon" great Pink Floyd song is somewhat misleading). As the moon rotates around the earth, it exerts a gravitational pull on the oceans such that during a 24-hour cycle there will be at least one high and low tide. Hence, tidal energy is renewable. Unfortunately, the tides do not always coincide with the peak demand times but the production of electricity output is predictable.
The technology used for the conversion of tidal energy into electricity is similar to the technology used in hydroelectric power plants. There are various systems that are used to harness the potential energy supply by turning a turbine, to turn a generator, to electricity. The approaches for tidal power are either a barrage (similar to a dam), to create a catchment zone, or to directly ??? from the flow. With a barrage, you close off the flow — allow the tide to come in when it is much higher than the water height in the catchment area: the flow is opened and water rushes in. Before the tide goes out the high tide water is captured, the flow stopped and the flow is started again when the tide is low so the water flows out of the catchment area. The process then repeats.
Tidal power. Tidal power is a form of hydro power that converts the energy from the natural rise and fall of the tides into electricity. Tides are caused by the combined effects of gravitational forces exerted by the moon, the sun, and the rotation of the Earth.
Tidal plants can only be installed along coastlines. Coastlines often experience two high tides and two low tides on a daily basis. The difference in water levels must be at least five meters high to produce electricity. Tidal electricity can be created from several technologies, the main ones being tidal barrages, tidal fences, and tidal turbines.
Tidal barrages are the most efficient tidal energy sources. A tidal barrage is a dam that utilizes the potential energy generated by the change in height between high and low tides. This energy turns a turbine or compresses air, which in turn creates electricity. Tidal fences are turbines that operate like giant turnstiles, whereas tidal turbines are similar to wind turbines only underwater. In both cases, electricity is generated when the mechanical energy of tidal currents turns turbines connected to a generator. The generator produces electricity.
Ocean currents generate relatively more energy than air currents because ocean water is 832 times more dense than air and therefore applies greater force on the turbines. Tidal power is easy to install and renewable, having no direct greenhouse gas emissions and a low environmental impact. Because the ocean's tidal patterns are well understood, tidal energy is a very predictable energy source, making it highly attractive for electrical grid management. This sets it apart from other renewables that can be more unpredictable.
However, adoption of tidal technologies has been slow, and so far the amount of power generated using tidal power plants is very small. This is due largely to the very specific site requirements necessary to produce tidal electricity. Additionally, tide cycles do not always match the daily consumption patterns of electricity and therefore do not provide sufficient capacity to satisfy demand. That's tidal power.
The U.S. Energy Information Administration Tidal Power webpage [74] provides additional information on the three different tidal technologies: tidal barrages (currently in use), tidal turbines, and tidal fences are both emerging technologies.
While tidal power is a proven technology, wave power is an emerging one. There are a few different ideas ranging from using wave power to move air to make electricity, underwater turbines similar to wind turbines (but much smaller), or devices that articulate.
One concept for harnessing the wave energy is the oscillating water column principle. The take off for this technology is typically an air turbine. The most commonly used air turbine for this application is the Well turbine, which we will explain in this episode.
The water level in the chamber rises and falls with the rhythm of the waves and act as a piston. The air is forced forwards and backwards through the turbine and causes the rotation of the turbine. This generates mechanical energy that is converted into electricity by a generator.
The Wells turbine has a special feature. It always rotates in the same direction, regardless of which direction the airflow comes from. How is this possible? This is feasible because of the symmetrical shape of the rotor blades. As the air hits the rotor blade, most of the flow is deflected in one direction and pushes the blade in the opposite direction. Due to the symmetrical shape of the rotor blades, the same effect happens when the airflow comes from the other direction. Therefore, this Wells turbine always rotates in one direction, regardless of the air flow direction and guarantees the continuous rotation of the turbine.
The Wells turbine must be turned on initially. The airflow alone does not get it to rotate. This turbine is one of the simplest turbines for wave energy conversion. It has very few moving parts. None of them are in the water, need no gearboxes, is easy to maintain, and achieves an efficiency between 40% and 70%.
This turbine was tested in several research plants under real conditions. Limpert, the power plant on the Isle of Islay was the first commercial plant in operation between the year 2000 and 2018. It generated 500 kilowatts with two Wells turbines.
The Mutriku Breakwater Wave Plant in Bay of Biscay on the coast of the Basque country in Spain started in 2011. It has 16 Wells turbines and supplies 250 households with energy. The Wells turbine has the most operational experience and running hours of all air turbines for oscillating water column concept of harnessing the wave energy, and it makes a small contribution to the generation of sustainable energy.
The U.S. Energy Information Administration's Wave Power webpage [76] provides additional information on ways to capture the energy in the waves.
We have already examined how the electricity demand cycle changes according to the time of day, day of the week, season, and needs to accommodate temperature changes (due to electricity use in heating and cooling). Here are examples of the weekly electricity demand cycle for various months. Note that day and time have an impact on demand. Also, these are averages so the variance due to weather (especially cold/hot days and holidays are muted). When you use electricity it has a very significant impact on the cost to generate that supply (the peak will be more expensive than the electricity generated for the trough).
Thus, to meet this demand we need to have either extra generation capacity or electricity storage. The traditional approach was to have additional generation capacity, often smaller natural gas-fired "peaking" units that were activated when the demand was high. As these were not used for extended periods (and they were small) they were/are expensive to operate. The owners also need to be paid (a financial incentive) to keep this electricity generation in reserve for when it is needed (the hotter afternoons in the summer, colder winter mornings/afternoons). A few locations used pumped-storage: using coal-fired and nuclear-derived electricity at night (when the demand was lower) to effectively store the electricity as potential energy in water that could be returned to electricity when demand was again high via the hydroelectricity approach. In some cases, this was a cheaper option than the addition of new capacity that was needed for the then growing electricity demand (currently electricity demand growth is very low). Our current situation however is very different. There is now an ongoing transition towards increasing the renewable energy contribution from solar and wind. Both suffer from an intermittency challenge: so we need either many more wind turbines and solar farms (well-dispersed) to accommodate the expectation for always available electricity or we need electricity storage options. The closure of coal-fired plants and the impending closure of nuclear plants will make this challenge much greater (electricity was available with a high probability unless maintenance or unscheduled off-grid issues).
This was covered earlier in the lesson. It is one of the few electricity "storage" options that have been available for decades and at scale. Here the electricity is converted to the potential energy in the water that is pumped to a higher elevation. This potential energy is converted back into electricity when needed (peak demand or to fill in the gap if renewable electricity is not meeting the need). This supplies 95% of the electricity "storage" in the U.S. There are some other emerging options, however.
We have used rechargeable batteries for decades, such as the lead-acid battery in gasoline and diesel vehicles (used to start the engine). However, the cost of alternative batteries has significantly declined and large-scale electricity storage plants are now possible using advanced Lithium-ion batteries. These plants make money by buying electricity when it is cheaper (when the demand is low) and selling it when the demand is higher (and the electricity cost is higher). Alternatively, they are now being paired with wind and solar farms to permit a more consistent electricity supply. The cheaper batteries are also "driving" the transportation transitions to electric vehicles (the pun was intentional — sorry) such as Tesla vehicles. If we electrify the transportation market, we will need much more electricity production. Some experts also predict we may have electricity storage at home in the future using some of these batteries (not just for rooftop solar cells). Again the system would store cheaper electricity and would provide electricity to the home when electricity costs are higher — as well as providing backup power for grid disruptions (blackouts).
Thermal storage was discussed with concentrated solar plants. By using a molten metal salt, there is a heat source (heat storage) that can be used when the sun goes down or on cloudy days. This could be heated by other power-plants.
In 2010 the electricity generation in the US was dominated by a single fossil fuel: coal at 45%. By 2019 coal had declined to ~25% (the change is due to the availability of cheap natural gas with some wind, and limited solar). I expect coal will stay around this number (even with the closure of older plants) as their capacity factor will increase (produce more electricity by either being 'on' more often or generating more electricity (they often run well below maximum capacity). Natural gas is the leading source at 38%. Nuclear was the third (~20%) although the expectation is that this will decrease as units are dismantled than are constructed and as the total electricity production grows. Hydroelectric power was 7%, with the wind also contributing 7%. Note that petroleum (in the form of fuel oil and coke) did not contribute very much to electricity generation (~1%). We are still highly reliant on fossil fuels, and nuclear for electricity generation!
Note: Electricity generation from utility-scale facilities. Sum of percentages may not equal 100% because of independent rounding.
As we look forward the predictions are that coal and nuclear will decrease their contribution and stabilize while natural gas and renewables will increase.
Here is another chart showing the contribution to renewables. Note the increasing role of wind and solar.
The last few lessons have had an electricity focus. However, it is important for us to keep in mind that we also have primary energy: transportation, electricity, heating (natural gas and other fuels), and fuel for industrial operations. Note that we use a great deal of petroleum (we will see in Unit 2 that this is used in transportation fuels), and natural gas! Also, note the higher contribution of biomass within renewables. It is used as industrial fuel for steam etc.
Like the coverage map in lesson 1, this map represents a summary of lesson 3, providing you with a way to quickly refresh yourself on the big ideas and connections in this lesson. Hover over the text boxes for more information.
Accessible Version (word document) [52]
After looking at this map, please take the L03 quiz.
In Lesson 1 we covered electricity use in our daily lives, and in Lesson 2 we discussed the fossil fuel sources (natural gas and coal) of that electricity. In this lesson, we turn our focus to coal. Pennsylvania has provided more coal to the nation than any other State (and we live with the historic environmental challenges).
[Dr. Mathews is standing next to a pillar filled with coal in a room with other coal displays.] Dr. Mathews: You should know by now that I got my doctorate pretty much in this material coal, so it is one of my favorite things to talk about. And I can talk about this for several weeks and obviously bore everyone to tears. But today’s lecture is about this material coal, the true black gold. This is a coal column that is 100 years old. Today we are going to talk about how we get this out of the ground and how we process it and move it around. And the origins of coal; where did it all come from? That and natural gas. [Video ends]
The main energy source powering our modern life comes from the remains of plants (coal and coalbed methane) or phytoplankton (oil and natural gas) that was buried millions of years ago. Coal was a key component in the industrial revolution, its extraction has long been associated with danger, poor work conditions, and death. It is commonly thought of as a dirty energy source. The truth is, however, that coal continues to be a critical piece of our energy puzzle, and will continue to be so for some time. To understand the role that coal plays in our energy system, we'll explore its origins, qualities, examine extraction, remediation, and historic environmental challenges. We'll also look into the vastly improved methods for extraction, transportation, and use — which will explain why coal continues to be among the leading sources of electricity production Worldwide. Its greenhouse gas emissions (specifically CO2) remain a challenge, however, and with cheap natural gas being available in the U.S., coal is being used less. It will, however, be used extensively in China, India, and other nations.
Success in this lesson will be based on the following learning goals:
Enjoy your trip underground in Lesson 4: Coal
Question: Have you ever seen lumps of coal?
Click for answer.
This is a brief overview of the Origins of Coal from the World Coal Institute. As you read, please note that coal can be very different depending on its maturation (extent of maturing). Also, note that we classify coal according to its properties (the classification being called "rank"). It's important that you understand that the term "rank" here does not mean a true "ranking" but rather a classification. All coals are used for combustion within electricity generation, select bituminous coals are more valuable and are used for coke making (used in the manufacturing of steel from iron ore).
Read up on coal here with the goal of understanding coal rank and how coal forms (it is fair game for the exam — see the learning objectives).
Coal is one of the fossil fuels (along with crude oil, natural gas, oil shale, and tar sands). The name fossil fuel invokes the notion that at one point in time coal was alive. Well, almost, the coal precursors, mostly the plants, were alive growing in the sunshine. We know this because we can find fossil imprints of leaves and branches in coal, amber containing flies, and other organic material preserved, bark imprints in the coal, coalified trees, coalified roots, and biomarkers which are chemical compounds produced by living organisms, etc.
You've seen the carbon cycle once already in relation to Biomass back in Lesson 3. This time, focus on how the living matter (plants and animals) breaks down but the decay is limited, creating the organic basis for fossil fuel formation.
Recall that photosynthesis is the process by which plants absorb the sunlight (solar energy), store it, and convert it into energy to grow and survive. The plant takes in carbon dioxide (CO2) and water (H2O), stores and uses the glucose to grow and live, then releases oxygen (O2) back into the environment.
When plants die, this process simply works in reverse. Walking through almost any forest is the best way to witness the decaying process in action. The forest floor is generally strewn with dead and decaying leaves, branches, and sometimes entire trees.
Normally the process of growth and decay occurs but in the formation of the fossil fuels the normal decay path did not occur. Instead, the organic material is somewhat preserved. The key is the absence of oxygen, which is necessary for the normal decay process. Bogs are ideal for this to occur so in swamps (a particular type of bog) the plant material dies but is protected from the normal decay process by the stagnant water, which is low in oxygen. Decay still occurs but the bio-resistant material (the chemical structures which are resistant to the bugs dining in the swamp) is enriched. Over long time periods, considerable quantities of organic material might be buried in the swamp which might eventually form the material peat. As the peat is aged and buried deeper in the ground the slow coalification process (the maturation process for coal) continues and eventually transforms peat (a coal precursor) into low-rank lignite coal. This brown/black coal is typically a "young" coal (~60 million years old). With further maturation, long time periods (millions of years), warmer temperatures (within the earth), and higher pressure as the coal is buried deeper, other ranks of coal are produced: subbituminous, then bituminous coal. If there is uplifting, then anthracite coal can be formed because of the high temperatures and stresses involved. Magma can also bake some coals enhancing the rank in some locations. (refer back to the World Coal Organization PDF on the previous page for a refresher of coal rank: lignite, subbituminous, bituminous, and anthracite).
During the various stages, other materials such as minerals might be washed into the bogs, mud will form clay which will turn to shale over the years. The organic material will have contained inorganic material (it forms the ash left behind in a wood fire). Thus, coal is not pure organic material, and as the coalification process is over such long time periods we have different ranks of coal in the US coal of different qualities.
Coal is very old. The formation of coal spans the geologic ages and is still being formed today, just very slowly. Below, a coal slab shows the footprints of a giant armored salamander (the footprints were made during the peat stage but were preserved during the coalification process).
The organic matter that falls or is washed into the swamp will be protected from the usual decay process because of the low oxygen concentration in the water. Decay will occur in the less bio-resistant material, leaving behind the bio-resistant organic material. Eventually, this material will form peat. With burial and the "cooking" of the earth (as you get deeper, it gets warmer) for geological time periods, low-rank coals will form such as the lignite shown here for North Dakota. The process of coal formation might repeat itself and so layers of coal and rock are present in many locations within the US. There the deeper you go the higher the coal rank. In Pennsylvania, we have bituminous and anthracite coal, the mountain formation transformed the bituminous coal into anthracite and it can occur at the surface.
There are a few mining operations (historic) in northern Centre County (where the University Park Campus is located) but coal occupies much of the western portion of the state (bituminous rank) with a smaller but well-defined anthracite region in the north-east.
Coal is well dispersed throughout the continental United States. We have about 25% of the World's reserve of coal, and all the various coal ranks. The yellow is lignite, pale green is subbituminous coal, the other colors are various bituminous ranks, except the orange in NE Pennsylvania which is anthracite.
Here is a global view of the deposits. The major coal regions (and users) are China, the U.S., India, Europe, and Australia (major exporter).
The take-away message from this now dated graphic below is that Asia (specifically China) is the highest user for most of the Worlds Coal (still true in 2021). The growth was related to the transformation to an economic powerhouse and increased electricfication.
We also have lots of coal, far more than the energy in oil (shown in red) and natural gas (shown in brown) in the U.S., Asia (China and India), Europe, etc.
There is also a robust international trade in coal (see the coal transport page later in this lesson).
We have learned that coal is very old. Much of the Pennsylvania coal is about 300 million years old, so, much older than the dinosaurs. To put it in perspective, the Jurassic era was about 80 million years ago! But, coal is still being formed today so we have a range of coal with highly variant properties (and quality), from a brown coal, which is relatively young, to a bituminous or anthracite coal, which is relatively old. The material is distinguished by a rank system that is very informative regarding how we expect that coal will behave during the combustion process or other coal applications.
There are 2 officially accepted methods of determining the rank of a coal in the U.S. (but numerous other approaches). Which approach you use depends on the calorific value of the coal. There are 4 general rank classifications, shown from lowest to highest rank;
Coal | Rank |
---|---|
Lignite | low-rank |
Subbituminous | low-rank |
Bituminous | high-rank (soft coal) |
Anthracite | high-rank (hard coal) |
There are lots of sub-classifications but we only need to consider the groups. The rank of coal is an important feature of the coal, it is used for taxation purposes, contracts, etc. Coals that have a calorific value below 14,000 Btu's are put into a rank classification based on the calorific value. Coals with calorific values above 14,000 Btu's use the proximate analysis to determine rank (specifically volatile matter or fixed carbon values).
When coal is burned, the exothermic reaction produces heat;
C + O2 → CO Carbon and Oxygen yields Carbon Monoxide
CO + O2 → CO2 Carbon Monoxide and Oxygen yields Carbon Dioxide
2 H + O2 → H2O Hydrogen and Oxygen yields Water (Steam)
This is, after all, why we burn coal! But how much calorific energy we obtain is dependent on the chemical composition of the coal, which tends to change with maturation (age), so bituminous coal will provide more energy than biomass, lignite or a subbituminous coal. This is very important information when buying coal or, as we will see later, very important information when determining pollutant emissions.
This has 4 components, which are useful in determining price and behavior of the coal during combustion, as well as some other quality issues.
Moisture adds mass to the coal which impacts the transportation costs as well as reducing the useful energy obtained from the combustion of the coal. The steam produced from within the coal (from moisture) is not used to turn turbines but rather goes out of the stack. In low ranks coal, such as lignite, water might be 60% of the total mass! Moisture levels are rank-dependent and bituminous coals may only contain 1-2% moisture by weight (subbituminous coals will have more moisture ~30% unless the coal has been dried). High moisture levels and high oxygen content is why the calorific value is low for lignite and other low-rank coals.
Most coal is burned, how easily it burns depends on the quantity (and the quality) gasses that are released when the coal is heated. Under prescribed heating rates, under nitrogen (so no combustion losses), and times, the weight loss is determined to be volatile matter. This value is used in rank determination for coals above 14,000 Btu's/lb. Coals with a higher volatile matter yield are easier to burn.
Coal contains inorganic material too, which we call mineral matter. This diluent impacts transportation costs, and after the combustion process, the coal will leave behind the now chemically altered mineral matter (high temperatures, as well as oxygen, will change the composition of the mineral matter) into ash, which will have to be removed influencing the combustor design and operation. Thus, the coal is combusted, leaving behind the ash which is weighed to roughly determine the contribution of mineral matter to the coal mass. Remember coal is purchased on a per ton basis so ash values are important indicators of quality.
After the volatile matter determination, the char contains fixed carbon and ash, if we know the ash values the subtraction of the moisture, volatile matter, and ash produces the fixed carbon. Fixed carbon -= 100 - moisture - volatile matter - ash values
This analysis determines the relative abundance of the organic elements that are contained in the coal. It is influenced by the rank of the coal.
Element | Normal Contribution range (%) in Coal |
---|---|
Carbon | 60-90% ( Higher Rank - Higher % ) |
Hydrogen | 2-6% (Higher Rank - Lower %) |
Oxygen | 1-30% (Higher Rank - Lower %) |
Nitrogen | 1-2% (No real change with Rank) |
Sulfur | 0.5-5% (no significant change with rank) |
We will find out later in the course that nitrogen and sulfur contribute to environmental problems when their oxides are released into the atmosphere following combustion. For those who are impatient, you can find out more information concerning the NOx and SO2 [83](and sulfate aerosols) emissions here. Nitrogen values for coals are typically around 2%, so nitrogen content does not influence the coal quality when comparing two similar-rank coals. Sulfur, however, can vary dramatically and is certainly an element that impacts coal quality. High S content negatively influencing the price of the coal, making it cheaper as more expense will be incurred in cleaning the coal or reducing the SO2 emissions (acid deposition-Lesson 10). The S content along with the calorific value is useful because you can use it to predict the SO2 emissions per million Btu's of thermal input (which is the measure used in the clean air act of 1990 to ensure pollution controls).
Thus, several measures impact coal quality– how much organic material is actually in the coal (minus ash and moisture values) as this impacts transportation, the quantity of useful energy that will be produced (calorific value and moisture content), removal of the ash from the boiler (ash), and emissions from the combustion process (S content). Of course, the quality of the coal will impact the value of the coal so remember the $ is an important influence on the cost of the electricity, and where the coal is purchased from (transportation).
Select bituminous coals can be used in coke manufacturing for use in steel production. They need to have low S, low ash yield, and other properties, but they are more valuable. The Pittsburgh coal seam is a classic example and one of the reasons that it is Steel City with the Steelers (not Stealers) football team, and Iron Brew beer.
As coal ages, it undergoes chemical and physical structural changes. You will see below some of the proposed structural changes that occur. I love this stuff! This is very much why I am Dr. Mathews: 6 years of study and the generation of a few structures like these. The structures here are simplistic representations of some of the structural features found in coals of those ranks. We still do not know the structure of coal, because it is highly variable and complex. As the structure changes one of the gases it produces is Coalbed methane, which supplies on the order of 8% of the domestic natural gas production and so is an important unconventional resource (shale gas is also an unconventional resource and a much larger contribution to the domestic natural gas supply).
Look at each of these three models. They are very different in appearance. Look at the hydrogen and oxygen atoms -there are fewer as the coalification proceeds. The anthracite coal is the most carbon-rich. These changes influence calorific value.
Okay, a few structural changes are evident as coalification proceeds from low-rank coal to anthracite:
The only way for the structure to become more carbon-rich is to either 1) have carbon added (not likely 100's of feet down), or 2) lose other material. The latter is the case here. As coal matures, the oxygen is lost probably as water and hydrogen as methane (as most of the oxygen formed water there is not enough oxygen left and so the hydrogen generated from the coalification process is lost as methane). The methane will either migrate to the surface or into other structural traps, with a considerable quantity being retained in the coal.
For over a century, this coalbed methane has been problematic. In the right mixture with air, it is explosive. Coal mine methane explosions are among the worst mining accidents. Methane in the mine causes ventilation problems trying to prevent the methane content from building up. If the levels are too high in modern mines (in the US) work has to shut down for hours before the miners can return, causing huge losses in productivity.
In the (4:13) video below, Dr. Mathews describes the perils of being a miner and the cues miners used to avoid serious danger (and explains why the lamp doesn't explode!)
[Video opens with Dr. Mathews standing next to a pillar of coal.] Dr. Mathews: One important thing about mine safety is the gases. Now, there are several things that can go wrong in the mine. The roof can fall in on you, you could have an explosion, or you could get trapped or crushed by any of the machinery or the explosive devices you are using. One of the key things, however, is the gases. And this is a very important miner's safety piece of equipment. [Dr. Mathews hold up a lamp-like object that is in his hands.] Dr. Mathews: This is a Davey's Miner's Lamp. Probably about eighty years old by the looks of it. What I would have is some fuel source, probably kerosene back at about 1920. Prior to that, we may have been using Sperm Whale oil. And there is a naked flame. One thing you don't want to have in a coal mine is a naked flame. And so it is protected by this wire mesh. When I was in the mine, if I was to lift it up, and I would see a bluish tinge, and if the light would get brittle, I would know that there was methane in the coal mine. Now methane now-a-days is a good thing. It is a very valuable resource. But if you are in a coal mine, one spark, which is very easily done, is going to start an explosion, if it is in the right mixture. And that could kill everybody. So certainly there have been coal mine explosions where more than 100 people have died. It is one of the main reasons coal miners today will still wear a very thick leather belt with their name stamped on it so you can find their remains. But of course, there are other gasses in the mines as well. If you lowered your miner’s lamp and the light was to go dim, when you put it toward the bottom of the mine, it means there is probably not a lot of oxygen there. There is probably either carbon monoxide or carbon dioxide. Carbon monoxide will kill you. Carbon dioxide means there is a lot less oxygen in the air and you might want to leave. It is one of the good ways of staying alive. The other methods of using are of course high tech equipment which we have now, but in the good old days, you would use a canary. A canary has very small lungs and breathes very fast. [A picture of a miner holding a canary in a small cage.] Dr. Mathews: If your canary stops singing, and is lying in the bottom of his cage, it is probably a good time to leave. If you are in a drift mine, that is a mine that goes into the slope of a mountain, then there is probably going to be rats there as well. If they start leaving it means either the roof is going to come down, or it is the presence of dangerous gasses. Thank goodness for rats and canaries. [Video ends]
Methane is also a greenhouse gas (more on that in unit 3). So now that natural gas has value, so does Coal Bed Methane. Coal Bed Methane is a danger to the miner, as methane is an explosive gas (when it is present with air at the correct concentration levels). It is there because of the maturation of the coal and the changes in the molecular construction of the coal. With age, the coal becomes more carbon-rich by losing oxygen and hydrogen in the form of methane. Now methane has more value, the methane in coal has value and is now being extracted. This can extend the lifetime of our natural gas supply. Locations with bituminous coal are extracting the methane from abandoned coal mines and from deep unminable coal seams. They also look to extract the methane from coal seams that haven't been mined yet, which have the added benefits of creating mining operations later that are safer and less expensive, because the air flow into the mine can now be minimized, saving time, money, and overall productivity. We will see in unit 3 that we might be able to store CO2 (sequestration) within deep coal seams as a climate change mitigation option.
The picture to the left is a dirty, smelly Dr. Mathews as happy as a pig in swill! It was taken three decades ago when I was just starting my Ph.D. studies here at Penn State. Thinner and braver in those days, I would venture into mines looking for coalified trees. Six years later I had a doctorate in Fuel Science - "Following the changes in the constitution of rapidly heated bituminous vitrinites." Ahhh, the good old days!
Mining has always been hard work, but without the availability of modern machinery, lots of manpower was necessary.
For an in-depth and very interesting look into the jobs of miners, and the methods they use to do their jobs, check out this United Mine Workers Association [88] link.
The following video from Catapillar Mining provides a good overview of room and pillar mining.
In room and pillar mining, the coal seam is mined in a checkerboard style, leaving pillars of coal to support the roof, which allows for instant coal access with a relatively low invest compared to longwall mining, however, only utilizes the coal reserves between 50% and 75%. It is a mining method of its own right, as well as a supporting technology to develop roadways in order to prepare the coal face for a long wall operation.
In room and pillar mining, continuity is the key to profit, from the continuous miner to the continuous flow of material. The coal is cut by a continuous miner, which delivers the product to haulers. They bring the product to feeder breaker units that prepare and deliver it under the belt system.
While feeder breakers are moved only occasionally, the other equipment is in constant motion, so maneuverability, cableless operation, and maximum load capacities are vital. With a full range of battery or diesel powered vehicles, Caterpillar has an answer to every challenge in room and pillar mining. It all starts at the coalface with the right cutting technology.
Today's continuous miners are designed to cut at highest efficiency while keeping dust levels to a minimum with water sprays and dust collectors. They are available for operations from as low as 70 centimeters up to a maximum of 5 meters. From production to the delivery point, it's just a question of volume and velocity.
That's easy physics for our range of utility vehicles. Being equipped with rubber tires and an industry leading capacity, they keep the circulation of product and material at a healthy and profitable level. The roof bolter follows production on its tail to create a safe mining environment. Driving the bolts into the roof in a safe and efficient way is most important in this real hands-on job.
Therefore, ergonomic controls and easy material access are one of the most important features in our roof bolters. The Scoops Multipurpose Contoured Bucket will carry equipment, serve as a multi-tool, or clean roadways and feeder sections. Extended battery life and a dual motor option make it versatile yet powerful. The scoop has often been called the miners Swiss army knife. As a matter of fact, it is a real workhorse too.
The image below provides a birds-eye view. The pillars are a bit large but you get a general idea. The continuous miner (the machine with the big drum and all of the teeth) extracts the coal, it is loaded directly or picked up by the coal hauler that takes the coal to the conveyor system for transport out of the mine. The roof bolter adds metal rods to the mine ceiling so the rocks don't fall (the roof bolts are needed for safety). Obviously, the pillars are coal and so we leave behind 30% or more of the coal.
Mining anthracite is quite different from bituminous coal (where the seams are mostly horizontal). Anthracite seams can be at a 60° pitch so slightly different techniques are used either mining the seam from above or below.
The productivity in underground coal mining has dramatically increased due to mechanization. Watch this video of a longwall miner that can run the length of a football (American) field or longer (3:25 minutes).
Whenever mining coal underground, longwall mining is a highly productive, efficient, and safe way of doing it. The coal seam is mined cut by cut with a plow or a shear until a complete panel is mined out. Such a longwall panel would typically be 3 to 4 kilometers long and 250 to 400 meters wide.
Four seam heights of up to 1.8 meters or 71 inches, the plow is the cutting tool of choice. It travels fast, with speeds of up to 3.6 meters per second along the coal face pulled by a plow chain that transmits a force of up to 2 times 800 kilowatts. The plow is cutting coal at predefined depth up to 25 centimeters or 10 inches.
In seams from 2.3 meters to 6 meters and above, the shear has proven to be the most efficient cutting technology. It travels typically with a speed of 16 meters per minute, while normally cutting 100 centimeters with its powerful cutting drums, generating a production capacity of 5,000 tons per hour. Constant loading of the face conveyor, which transports the coal to the crusher and the belt, is the goal.
To fulfill this task, the armored face conveyor can be equipped with three drive systems, each holding a power of up to 1,800 kilowatts. This power package enables them to handle extreme peak loads. The AFC provides rail on which the cutting device travels. But it's not only for this, but also for the capability to handle all the strains, especially on the chain and the constant wear and abrasion, that the AFC is called the backbone of the longwall.
Roof supports are vital, not only for a constant production and advance of the longwall but for the safety of the miners. With a bearing force of up to 1,750 tons each, they can handle even severe roof and floor conditions.
They are available for a seam heights from 0.8 meters to 7.5 meters.
Our roof supports have been tested to advance 60 kilometers and more underground before a complete overhaul is necessary.
Integrated automation has become unrenouceable in longwall mining. Constant optimization of the entire longwall system, control of thousands of kilowatts of power in motors and drives, as well as a few 100,000 tons of combined yielding capacity of the roof supports surmounts human abilities.
A network of intelligent control units collects and shares data, thereby optimizing the entire longwall system, achieving maximum productivity and availability. Automation systems also keep the miners away from hazardous areas, increasing safety standards even further.
What is the role of the shearer, roof supports, face conveyor, and gob? The machinery behind the operator holds up the roof and then the whole device walks forward leaving the roof to fall safely behind the work area. Thus, the extraction is much higher and more of the coal is removed by this technique. Safety has improved in the mines but one of the reasons for lower loss of life is the reduction in the number of miners because of productivity enhancements and fewer miners.
Roof falls are a major danger in coal mines. The roof is bolted together with meter-long bolts but the roof has to be checked anyway. How the roof "sounds" is a good indication of the stability. If you happen to have rats handy, and they leave the mine, it is a good idea to follow, as their hearing can often pick up the sound of the roof straining when it's not audible to humans.
The small coal dust particles (and silica particles) enter the lungs and stay there. Long-term exposure produces a debilitating disease and often premature death. In the early years of coal mining, a miner was an old man at age 44 and the life span was not expected to be much longer.
One of the major dangers to coal miners had nothing to do with physical injury (although that is highly possible, especially in the "good old days"), but rather with lung damage. The medical community calls the infliction pneumoconiosis but the miners know it as black lung. All coal mining methods will produce some dust but underground mining methods produce more and the dust (small coal particles - smaller than 100 microns) in an enclosed space.
Many miners still do not wear masks to filter out some of the particles but the technology is much better at controlling dust, water sprays help to reduce the problem as well as air handling systems. Fewer miners in the mine also help to reduce exposure, as does the remote control machinery that allows the miner to operate the continuous miner of a roof bolter from several meters away. Historically, this was a massive problem, resulting in the premature death of perhaps 100,000 miners. Modern miners can still "get" black lung disease and it is increasing in some locations.
More information if you're interested in learning more about these hazards is available from the United Mine Workers Association's Black Lung webpage [98].
In some locations, the coal lies deep in the ground, but in others, only a few feet from the surface. If the material above the coal (overburden) can be removed, then there is easy access to the coal. Sometimes the tops of mountains can be removed to expose the coal, other times vast acreage of mines is created. Either way, this technique requires the ability to move vast quantities of rock and coal. Surface mining is an expensive operation, with environmental challenges, and a great deal of expense. It can, however, extract lots of coal with which to provide the engines of industry (and the computer chips, etc.) the energy they require.
The removal of both the coal and the overburden is performed with some of the largest mining vehicles in existence. First, the overburden is drilled into with power drills. The intent is to use explosives to fragment the various rock layers into manageable chunks that can be removed. Then, the holes are filled with an explosive mixture of fuel oil and fertilizer. The fragmented rock is then scooped with very large buckets via draglines. The process then repeats but this time the coal is fragmented with explosives. This is done by truck, or by miles of coal conveyor belts. After collection, the coal is transported to the breaker. There the coal is crushed and a cursory cleaning is performed to remove the large pieces of rock.
A special form of surface mining is Mountain Top Removal. This occurs in locations such as West Virginia and eastern Kentucky. This is a highly contentious form of mining that provides jobs and tax benefits to the region, but damages streams and removes mountains. Dam bursts of coal dust retention ponds have also been a problem.
[101]
[102]
[103]
Click on the images to learn more about what you are seeing.
The scale of these mines can be very impressive, check out a drone view of a surface coal mine.
Mining reclamation is now required for all active mines, but that was not always the case. There are many sites where the work finished and the miners and the owners just walked (or ran) away. Not only is mining reclamation the norm these days, but it is also required. Mined land is required to be returned to its original contours. A tax on every ton of coal (15 cents for surface coal) helped to fund "Superfund", a large-scale government environmental program for cleaning up the abandoned mine sites. The fund, which started in 1978, is now in the many millions (fines, interest, and late payments are also included). The ash from fluidized beds is currently used in the anthracite region to fill in the open pits from long ago abandoned strip mines. This reclamation and others help to remediate acid mine drainage, prevent landslides, and aids in recovering land for other useful purposes, such as land development to the West of Pittsburgh International Airport.
So after the coal is removed the overburden is moved back, leveled, the topsoil is returned, and vegetation planted.
Mine fires are a familiar and common hazard, and also an environmental concern. The movie here shows a particularly unique occurrence, which is a fire that simply won't go out. The people of Centralia have had the unique problem of dealing with this fire for some 40 years now.
Here is an interesting YouTube video on the Centralia Coal Mine fire. The highway there has now been covered with overburden and it is dangerous, so don't go. Watch up to the 3:20 mark.
There's a small town in America by the name of Centralia in Pennsylvania that looks like it has been hit by the apocalypse. The town was left abandoned after a coal mine fire began to burn more than 56 years ago.
Underground mine fires are common across the globe. There are thousands that have been burning uncontrollably for many years. Australia's Burning Mountain is believed to have been burning for 6,000 years.
Centralia's fire started in 1962, when residents turned an old strip mine into a dump and set the rubbish alight. The fire spread through an unsealed opening to the underground coal mines, igniting a seam of coal. And the fire has been burning to this day.
The fire stretches 12 kilometers and burns underneath an area of 15 square kilometers, 300 feet below ground. Authorities say the fire could burn for another 250 years.
The fire continued to rage unchecked into the 1980s. Giant plumes of smoke and deadly carbon monoxide gases billowed from fissures in the ground.
The local highway cracked and collapsed. Trees were bleached white and petrified. And people complained about breathing problems.
After estimating the cost of extinguishing the fire at over half a billion dollars, the government opted to raze the town and relocate its residents. Centralia used to have a thousand people living in the town. About five residents still live there today despite there being nothing there.
All real estate in the town was claimed under eminent domain in 1992 and condemned by the Commonwealth of Pennsylvania. The remaining residents were being forced to move. But in 1993, they started to fight for the right to stay.
After a lengthy legal battle, state and local officials reached an agreement with the seven remaining residents in 2013, allowing them to live out their lives, after which the rights of their houses will be taken through eminent domain. There is very little left in the town of Centralia, except for roads that lead nowhere and a few scattered buildings for the remaining residents.
Pennsylvania Route 61 used to stretch through Centralia. But it was destroyed by the underground fire. And cracks tearing through the tar would make you think a severe earthquake struck the area.
The town now mostly attracts tourists who visit an abandoned highway where many profanities and obscene pictures are sprayed onto it. Over time, the highway has earned the nickname Graffiti Highway, It sort of reminds me of the Cadillac Ranch, where there are 10 Cadillac cars facedown in the dirt. And people visit the cars to spray paint onto them.
When you see before and after images of the town when there was a thousand people who lived in it and now 5, it is very similar to the before and after images of Hiroshima. One picture had a whole city full of buildings. And the next is just an expansive parking lot. You'd be forgiven for thinking the town was nuked and wiped off the face of the Earth.
I asked a local YouTuber by the name of Joey Underground who let me use his footage for this video, does the ground still smoke, as I did not see any smoke in recent videos. He replied, it's smoking in certain parts of the woods. But the streets are no longer smoking. And you can only see the smoke on freezing cold days. I was there in March 2018 and couldn't see any smoke anywhere.
I'm not sure if it's love for the town and the house they live in or stubbornness, but when you think of what the remaining residents have to live with-- dangerous gases, cracks forming in the earth and roads, a raging fire below the ground they live and walk on, and an ever-present threat of sinkholes forming under their feet-- you have to ask yourself, would you stay? Anyway, that's the end of this video. Thanks for watching. And we'll see you next time. Bye, bye.
Acid mine drainage is an issue in both the Bituminous and Anthracite regions of Pennsylvania. Pyrite in the exposed coal (underground or on the reject (Culm/Gob) piles) acidify the water.
More on this in Lesson 10: Acid Deposition [107].
[Video opens panning down a discolored stream.] Dr. Mathews: This is a beautiful area of the anthracite region. This is one of the many sulfur creeks. It gets that name from its yellow or orange color in nature. This is due to acid mine drainage. What happens is the iron discolors the bed, the stream bed, with this yellow coloration, it is called a yellow boy, and it is actually iron hydroxide. Unfortunately, it means that the stream is in very poor health and it is not a good spot to go fishing. It is very sad to see the beautiful areas of this anthracite region devastated in this manner. [Video ends panning the stream.]
There is a correlation between coal mining locations and the occurrence of acid mine drainage.
We know that coal contributes a great deal to our production of electricity. The challenge is how to do it cheaply and in an environmentally responsible manner. Carbon dioxide emissions are a new challenge that we now have to face. More on this later in the course.
Here is how I think the lesson materials tie together the coal combustion materials in lesson 02 and the environmental challenge of acid mine drainage that we cover in lesson 10. This coverage map does not have interactive text so give some thought to what are the important concepts.
There are several other challenges that our historic (abandoned) coal mines contribute to.
You have to be careful when walking in the coal mining regions. The photograph below shows a high wall left when the mine was abandoned. This was illegal after 1977 but many abandoned coal mines still remain. High walls such as this are a danger for wildlife, off-road drivers, bikers, and hikers.
Does anyone fancy a dip? On a hot day, the old pits that have become flooded are a tempting swimming hole. However, they are sites with high drowning fatalities both due to the very cold deep water and the fact that the pools can be very acidic and lead to acid-shock deaths. Stay away.
Worried you may live in a mining area? See the Pennsylvania Mine Map Atlas [112], and perhaps consider subsidence insurance. Subsidence is the gradual caving in or sinking of an area of land. Mining subsidence occurs when the hallowed out earth from the mines begin to cause the ground to shift or sink. If you live in a subsidence-prone area you can expect the cracking of walls etc. as the houses settle. In some cases, the house will become uninhabitable and will need to be demolished.
The production of coal is directly related to the energy demand that is related to economic production. Another reason for the increase in coal production is an increase in the population. My two daughters are certainly using lots of electricity. Cold winters and hot summers are also important components in the overall coal demand. However, climate concerns and changing economics of cheap natural gas and increasingly cheaper renewable energy (initially wind and in the future solar) are having greater contributions and many older coal power plants (coal-fired utilities) are closing thus reducing the U.S. demand for coal. Some of the coal-plants generating electricity have also switched over to natural gas.
I expect most of you are familiar with coal, as most will have Pennsylvania ties. You are probably well aware that the number of mines and the number of coal miners has been dramatically reduced in the last 20 years. There are many good reasons for closing a mine: the coal might have been mined out, flooded, safety issues, switching to cleaner coal (lower sulfur coal) due to environmental regulations, and of course or cost issues. Cheap natural gas is the latest challenge along with increasingly stringent environmental regulations for coal mining and coal use.
We also tend to mine more of the lower Sulfur coal much of which is in Wyoming in the Powder River deposit, which has a significant impact on this region (we have higher sulfur coals) and where our coal comes from. Thus, due to environmental pressure (sulfur emissions), and changing economics (cheap shale gas) many coal mines have closed in Appalachia with significant losses of employment.
How coal is transported is important, as often it will travel great distances (low S coal from the West to about 30 different States), across the State and International boundaries, and across the oceans. The United States is the "Saudi Arabia" of coal, so we transport coal across the nation. The final leg of the coal journey is normally to a utility site via rail. Lignite, however, is not shipped very far (much of the mass is water) so the coal-fired utility site (electricity generation site) sits next to the surface mine.
The conveyor is commonly used to move coal out of the mine and it can cover multiple miles carrying the material to the loading site for rail or barge transport. The coal may have been partially crushed in the mine to reduce the size of the lumps being transported. When the coal arrives at the utility site the conveyors are used again to put the coal in storage and to take the coal from the pile to the pulverizers for immediate use in the pulverized coal boiler.
Surface mines can also use very-large trucks to carry coal (or overburden) from the seam to the next location for transport. What is not evident in these pictures is the scale of these trucks, they are the size of some houses! Some mines are now using autonomous vehicles to transport coal (they are expensive vehicles and companies need to maximize their use).
Coal is commonly moved by rail. It was the movement of coal and goods during the era of "King Coal" that was responsible for an emerging infrastructure of railway lines that crisscross the country. There used to be a rail depot close to where the bus depot now stands in State College (there is a "Coal Lane" hidden there). You can still ride the rails from Bellefonte to Lemont. How important was the rail system? We currently ship coal all over the country from Wyoming because the coal has a low-sulfur content as the Clean Air Act restricts sulfur emissions from coal combustion. We also move over coal from the mining site to where it is needed (electricity generation, industrial use for steam generation, or movement to the cokers).
It is a common site in Pittsburgh to see coal barges moving coal up and down the river. It is an efficient method of moving heavy materials. Here it is often coking coal being moved to the coker sites, or steam coal (for use in electricity generation) connecting to the rail system. Please listen to the audio, Did you know this [119]?
Dr. Mathews: During the search for the Titanic it was actually the coal debris field which helped located it. These submersibles went down and when they found a very large debris field of coal, they followed that and when it narrowed down they found the Titanic. Of course when the titanic flipped upside down and the boilers burst through the shell of the hull of the vessel and all the coal, which was Welsh Anthracite, poured through the hulled. Now when I was in Orlando in 2002, there was actually a Titanic exhibition and they had actual artifacts from the Titanic there. You could actually go and buy a piece of this Welch Anthracite coal which had been picked up from the sea floor. Now I wasn’t about to spend 15 or 20 dollars on a small piece of Welch Anthracite coal, but it is pretty interesting. There is also another story which is of relevance to the Titanic with coal. And that is its actual manufacturer. It was built in Ireland, cheap labor I guess. The problem with building things in Ireland is that if they are making steel, essentially you needed coal for making the coke. Unfortunately, they used cheap English coal to do this and it had a high sulfur content, so it was a relatively poor quality. The problem with a high-sulfur content in coal is that you get a high sulfur content in your coke. If you have sulfur in your coke it ends up in your steel, because it goes into the iron and the iron into the steel. This is very undesirable because it makes the steel brittle and this probably contributed to the sinking of the vessel. So the moral of the story - don't buy vessels built in Ireland unless they are made out of wood.)
We move coal in a similar manner to the movement of oil in the equivalent of tankers. These sea-going ships travel the Great Lakes, and across the oceans delivering coal.
Wyoming has low-sulfur coal and it is in high demand. It is shipped mostly by rail to ~30 States.
We don't tend to store coal at the mine (instead we mine as needed) but we can store coal at the coal-fired utility. This allows for storage in case of supply disruptions (in winter) and permits the ability to pick up coal on the spot market (there are long-term contracts and coal that is available for more immediate sale). These piles are aligned into the wind to reduce dust problems. Supplies of 30 to 90 days are common.
There is also a robust international trade in coal by ship and rail with Indonesia, Australia, the former Soviet Union, and the U.S. being significant exporters. The coal goes to China, Europe, Japan, etc.
As with previous coverage maps, this map represents a summary of the lesson, providing you with a way to quickly refresh yourself on the big ideas and connections in this lesson. This is interactive so move your mouse over the topics.
Accessible Version (word document) [126]
After looking at this map, please take the Lesson 4 quiz.
Freedom and liberty - the flag, the Bald Eagle, the almighty dollar, Elvis, free speech, the Wild West, monster trucks, a passion of American life and our ongoing love affair with the cars and trucks we drive.
The ability to move about freely is deeply woven into the fabric of the American lifestyle, and so it is natural that Americans commit a significant percentage of time, money, energy, and emotion into their vehicles. At the same time, our quality of life has become highly dependent upon transportation, as so many of the materials, products, and goods are delivered to us via a massive and highly intricate transportation system. The energy to fuel all of this activity is available whenever we need it - although this has not always been the case.
This lesson is about the many ways in which people and products endlessly move about, the energy/fuel that it takes, and the environmental consequences. Like Lesson 1 on Electricity, this lesson is designed as an opportunity to connect the topic to your own personal experiences and to see yourself as a component of a larger system. But like Lesson 1, "the times they are a-changin." Watch the following (:56) video below.
[Dr. Mathews is standing off of a highway with vehicles passing by periodically.] Dr. Mathews: Today's lecture is all about transportation. I am standing out here at 322 it is the Mt. Nittany Expressway. Lots of people (goods and services) come up and down this route. When you think about it, think about all the things that move around. We have to have gasoline, crude oil transported. We have to have frozen vegetables. We have to have exotic fruits moved around. Not to mention moving people. I have flown from Europe to America and back again many times. I have been to Australia, China, New Zealand, etc. I have even traveled via canoe, boat, train, and air. I have even ridden my bicycle every once in a while. All of these things require energy and each of these things will have its own impact on the environment around us. [A loud truck drives by] [Video fades out]
Success in this lesson will be based on:
We travel with ease and often at high velocity (providing you are not in the big cities). Ease of movement is another one of those things that we take for granted, but think just for a minute about how important it is to the quality of your life and how the American way of life has been transformed by the automobile. Wal-Mart for example, would not exist unless we had our own cars, and although the bulk of this lecture is about personal transportation, think also about all the goods and services that have to move around the expanse of the United States of America and beyond!
We have already discussed some transportation issues such as how we move coal around: train, barge, and truck mostly and some natural gas and oil pipelines, tankers, and trucks. As my colleagues in the Mining Program (in the Energy & Geo-Environmental Engineering Department) like to remind us: if it does not grow then it is mined! (We do extract oil and gas without mining.) The metals in this computer, silicon in the glass, hydrocarbons that are the bulk of the plastics, building materials were all once in the ground (unless you are in a log cabin!) All this material is transported around the country, sometimes across the oceans. Thus, if you did not get the hint: TRANSPORTATION IS IMPORTANT TO THE QUALITY OF OUR LIFE. Unfortunately, our transportation system is not very efficient (I am thinking mostly of personal transportation for that remark), and contributes to some of the environmental challenges.
For those of you who have not flown, it can be a lot of fun. For example, on the way to India I saw an entire Game of Thrones season. Other times it can be a nightmare, the screaming kids, cramped surroundings, and that is just the drive to the airport! The advantage of flying is speed. Transatlantic flights across the "pond" take about 6 hours flying time. Most passenger jets fly at around 300 to 500 mph. To do this they fly at high altitudes where the air is less dense (thinner would be the popular term but think about it, how can air be thinner?) The lower resistance allows the plane to fly faster. As the flight is more efficient at the higher altitudes (32,000 feet or so) the plane can travel further. As you might guess moving people around via the airplane is not very efficient on an energy basis alone.
Noise pollution comes in many forms, and varies depending on whose definition you go by. Almost everyone would agree that airplane takeoffs [127] (text version [128]) are a type of noise pollution.
Aircraft weight also influences the quantity of goods the plane can carry [129]. (text version [130])
When my grandfather was a small boy, an orange or a banana was considered a fantastic Christmas present (bad behavior meant he would get coal!) We don't have the weather to grow oranges in the U. K., so his Orange would have come from somewhere else in the British Commonwealth, probably the British Virgin Islands (named after Queen Victoria, not the chaste locals), or perhaps Spain. Either way, about the only way of getting the fruit to the UK was via boat (you can fly more expensive foods in such as Lobster, but fruit is heavy as it contains a lot of water!) The trip is long, and expensive which is why a fruit was considered a treat. Listen to this example of the value of salt [131].
Text Version: Value of Salt
Dr. Mathews: Did you ever hear the expression, worth his weight in salt? Salt used to be a very valuable commodity. In fact, if you were Portuguese, at times, that's how you would be paid. That would be your currency, salt. And in the slave trade, a slave could actually buy his own freedom if they had enough salt. A very valuable commodity. Think about it, it has to come from quite far away, even though the salt water is surrounding us, energy is expensive. And to boil off the water to leave salt, which is what they do in Saudi Arabia to create drinking water, all require a lot of energy. So instead you need to transport salt over large distances. The salt trade, think about Lawrence of Arabia, think about trekking in the desert, looking for an old sea where the water is evaporated, like salt lake. In the UK spitting salt is considered to be unlucky. In fact you need to take a little pinch and throw it over your left shoulder to break the bad luck. So transportation of this salt would have cost an immense amount of money. Wars are fought over it. The whole salt trade, the whole spice trade has affected the shape of nations. It has affected national trade. It has affected war. The passage of religion. It has had a very major impact on the country and world we now know.
Most boats will use diesel as a fuel. It has a number of advantages over gasoline, the most important of those being its higher energy content. The downside, however, is that Diesel has emission problems with particulate matter and NOx, and traditionally there have been few environmental controls to control emissions on the trucks and boats that use Diesel. This is now changing, along with the development of cleaner diesel fuels (lower sulphur and lower soot-forming precursors), so cleaner diesel vehicles are beginning to be produced. Diesel also has a much higher energy content in a gallon than gasoline (so less filling up!)
The Icelandic fishing fleet is converting to fuel cells for their fuel of choice. An environmentally driven choice of fuel. More on Fuel Cells in a bit.
Ahhhh......the romance of steam trains [135]...... (Text Version [136])
Steam trains have long evoked feelings of romance and adventure, and these opportunities were long powered by, of course, coal. Diesel later replaced coal, and now in many locations, trains run off of electric.
If you fly into Orlando, the monorail you see at left will take you from the terminal (a terrible name for the place you board an airplane) to the baggage claim. You can see small sized trains like this in other exotic locations such as Morgantown, West Virginia.
Most of us, are at some point, going to own a car. Odds are that in the US that will be the gasoline-powered vehicle (although diesel, hybrid, natural gas, and electric vehicles are now available and increasing in numbers). The basics of the vehicle are that liquid fuel has the stored chemical energy that is released during the combustion process to power the car. It is an old technology. The Model T Ford ("available in any color as long as it was black"- Henry Ford) in the US was available in 1908. Diesel engines predate gasoline engines. Interestingly the Model T Ford managed 12 mpg - some of the passenger vehicles (SUV's for example) on the road 100 years later, achieve only a marginal increase at 18 mpg. This is one of the major issues with energy use - efficiency, measured here by miles-per-gallon (mpg). The lower the mpg the more gasoline is needed to cover the ~14,000 miles the average American drives annually, and thus more air pollution. This used to be a major source of the balance of trade challenge but now the U.S. is producing much more domestic oil and natural gas so imports are declining.
So almost 8 out of every 10 people in the US own a vehicle. This is much higher ratio than the rest of the world where much lower ratios are common. Car ownership, however, is increasing dramatically as the industrialization of the developing world continues. Recall too, that the population of nearly all of these countries is increasing, so the potential for more people to be driving more miles in a greater number of vehicles will, of course, create more pollution - at least given the current technology. China is one such example: lots of new vehicles but lots of pollution! Current technology, as we will see later in this lesson and others, is evolving. Our air is getting cleaner in the US (EPA air quality [137]).
Think about riding a bike, or roller blades - when you crouch low to reduce your drag (making you more streamlined), you reduce your wind resistance, allowing you to coast further before having to pedal or push off. In modern cars, having your foot on the accelerator doesn't mean you're actually accelerating - you could just be maintaining your speed, and working against the energy losses of friction and drag, which requires more energy (gas) just to maintain the same speed. Having a streamlined car helps to increase the mpg this way, or, in the case of sports cars, achieve a faster velocity.
We have discussed kinetic energy. Recall Ke=1/2mv2, thus, the heavier the vehicle (greater mass) the more energy is required to move the vehicle. Saving weight in vehicles is one way to increase the mpg, by taking out the full sized spare and replacing it with the "doughnut" tire saves weight and increases the mpg. Changing body materials to lighter plastics, metals, or fiberglass is another method. Making engines lighter by replacing the steel motor with ceramic components are also being considered. Please watch the following (:33) video. Vehicle mass is even more important with electric vehicles as they currently have driving ranges that are lower than desirable. The Tesla for example does not carry a spare tire (it comes with a tire change service).
[Video opens with Dr. Mathews standing in front of a corvette stingray.] Dr. Mathews: You might recall that force equals mass times acceleration. So if you have a certain amount of force made by a certain engine, you want to have a faster acceleration. One thing you could do is reduce the mass. This is what happened in the Corvette. It is actually made out of fiberglass so it could accelerate faster. If you lower the mass of the vehicle it will also increase the miles per gallon. Not the case here though, we are after speed. [Dr. Mathews gets in the Corvette.] [Video ends]
Heat losses from the engine, air resistance, and rolling resistance between the tires and the road all contribute to our vehicles achieving only about a 28% efficiency. This means that only 28% of the total chemical energy supplied in the form of gasoline is actually being utilized, leaving 72% of gasoline's potential energy content to go essentially unused. This is one of many areas in the automobile industry where future improvements are expected.
With climate change concerns, there will be significant pressure for more stringent standards for automobiles (President Obama's statements [138]). We have made some significant improvements in this area after decades of inactivity. However, the Trump administration has slowed the rate of this and other transitions — are potentially rolling back the efficiency standards (standards are under review).
Appropriate tire pressures are usually written on a sticker on the inside of the passenger compartment. Remember that the rolling losses heat the tire up and the gas inside, so don't measure tire pressure on a hot day after a long drive. Also check tire pressures again when the seasons change, for example in the winter you may need to add more air to pressurize to the appropriate level.
How you drive also influences your mpg. Check out the fuel economy website [139] and this MotoWeek movie clip [139].
You can always watch Mythbusters and argue about windows up/down/ac influences or tailgate up/down for you truck owners.
In 2017 there were the first indications that gasoline vehicles may be replaced by hybrid, electric, or renewable fuels. France is proposing a ban on diesel and petrol sales by 2040, and Volvo is dropping gasoline-only engines (will still allow hybrids) in 2019. So, pressure on gasoline is mounting but it has many advantages: dense energy (high calorific value), availability, and can be efficient with the correct vehicle. I expect we will still be using it the decades to come but expect climate change concerns to increase the pressure.
When men get together to discuss their prized vehicles, you can be practically guaranteed that the conversation will include, or completely be dominated by, talk about horsepower [140]. Before the motor vehicle, the horse was the vehicle of choice, the power source for moving supplies and goods, and a primary source of power behind the United State's early agricultural and industrial prominence.
The horse essentially did work for its owner. The more powerful the horse the more work it could do. A standard horsepower was defined as the mass that a horse could move in a specified time period. Suffice to say that since horsepower represents a rate of doing work, more horses means more work could be done, or the same work could be done more quickly. Standard lawn mower or snow blower engines now weigh in around 5 horsepower, riding mowers might be closer to 15, a typical car is in the neighborhood of 100-150 HP, and for you race car types, there are typically several hundred (figurative) horses under those hoods.
Please watch the following (:15) video:
[Video opens with a close-up of a spark plug.] [The spark plug it fed electricity and a blue spark is seen.] [We hear the noise of a loud shock.] [This is repeated several times.] [Video ends]
The combustion of the gasoline occurs because of the appropriate mixing of a vapor of the gasoline with air and a spark provided by the spark plug (see left). The battery in the car provides the electricity to create the spark; it is also used to run the radio, lights, and to start the starter motor to start the gasoline motor. The motor needs to turn over so the piston rises in the cylinder, compressing the air and gasoline mixture, which is ignited by the spark. The timing of these events is very important, hence the need for a timing belt. The resulting combustion produces hot gases, which drives the piston down providing the energy to run your car. The starter motor has started the engine and now is no longer needed, until next time.
Thus, the basic four strokes (for a 4 stroke engine) are:
Engine Stroke | Description |
---|---|
Intake Stroke | Air and gasoline (sprayed in a fine mist to permit better mixing of the air and gasoline) enter the cylinder. |
Compressions | The piston head rises, compressing the air/fuel. |
Combustion | The spark ignites the combustion/detonation, which rapidly pushes the piston down (via a crankshaft connection; turns the vehicle's wheels). |
Exhaust | The products of combustion are vented out of the cylinder on the way to the catalytic converter and the tailpipe. |
Once again, I suggest that the curious amongst you take a trip to the "How Stuff Works" website to see a more detailed presentation of How Engines Work [141].
The lead acid battery that sits under the hood in nearly all our cars is heavy, and not inexpensive (especially if you leave your lights on regularly). Considering the size and weight of this battery, and its purpose to just start your car, you can imagine the size, weight, and expense of the one that would be needed to actually power your car? This is the major reason that electric cars running on stored electrical power did not make it off the golf course and onto the roads
Interestingly, living in England, the milk would be delivered to your doorstep, every day except Sunday, by a fleet of electric "milk floats" which started in the 1970's. As we will discuss later, many of the new approaches in vehicles and fuels will occur in those organizations with a large fleet of vehicles.
When the Model T Ford was filled up with gas, variations in the production and quality of the gasoline sometimes caused "knocking" in the engine. This violent shaking of the engine caused excessive wear on the engine and limited its power. The cause was the self-ignition of the gasoline and air mixture on the compression stroke (2nd stroke - remember?). In a diesel engine, this is actually desirable, as they don't have spark plugs, but in gasoline engines, it's not a good thing. The knocking is related to the shape, size, and type of molecules found in the gasoline, which is pretty complex stuff - when you account for the added cleaning compounds and environmental packages, your gasoline can include over 100 separate compounds! Please watch the following (1:15) video:
[Video opens with Dr. Mathews standing in front of a large machine.] Dr. Mathews: I am here at the energy institute research facility. To my left is an octane rating engine. When you go to buy gasoline from the garage you have a choice of several octanes. Most of you will be buying 87. Iso octane, the octane number, is based on a mixture of iso octane and heptane. When you are buying an 87 octane gasoline, what it means is it will have the same knocking behavior as 87 percent iso octane and 13 percent heptane. The way that is tested is in a device exactly the same as this. What we will do is take an 87 percent mixture of iso octane, a 13 percent of heptane, and blend them together, and see how they behave in certain conditions in this particular engine. Then we will compare it with a complex blended mixture of gasoline. Remember gasoline is going to contain at least a hundred different compounds. So you are not buying octane, your not buying iso octane, and you are not buying heptane. They might be there in small quantities but they are not a majority of the components. What we are looking at is knocking behavior. If we get that undesirable, spontaneous combustion when we compress the cylinders and the gasses and the fuel in the air, and it self ignites, that is called knocking. That is completely undesirable in a gasoline engine but it is exactly how a diesel engine works. [Video ends]
This knocking can be eliminated by changing the composition (or size, shape, and type) of the compounds. One of the early octane booster compounds added to gasoline was tetraethyl lead. This has been banned now to reduce lead vapors that end up depositing lead in the bloodstream, which resulted in reduced mental capacity, particularly in children.
A bit more about lead. [142]
Now we are required to make many changes to our gasoline recipe to meet environmental challenges (more on this in the next lecture).
We jump in our cars and we drive, without thought of the pollution that is being released from the tailpipe (and other locations). It is the same when we turn on a light. These pages will give you an overview of the issues related to pollution from motor vehicles.
Why is this an issue? Pollution if dilute enough is not going to have an impact. Unfortunately, anthropogenic activities are concentrated in the metropolitan areas and so the primary and secondary pollutants can become concentrated enough to cause severe health problems and even fatalities.
Unit 3 essentially covers environmental impact and mitigation strategies for pollution issues. There are 2 answers that are nearly always correct: conservation and efficiency (there are others that are correct too).
If we drive less we use less gasoline (I will never use the term gas to mean gasoline, petrol perhaps or if I feel a bit French 'Benzene", but that is a rare event ...feeling French.), we produce less emissions, and reduce our environmental impact. Unfortunately, the average number of miles we Americans drive (yes I am a citizen now) is increasing. We drive about 14,000 miles a year. If we can reduce that distance, we would be better off (reduce emissions). We tend to drive more after 9/11/01 too, and fly less. So how to conserve:
If we drive the same distance but do so with more efficient driving tactics, or with more efficient equipment, or we have more people in the car then the fuel used will be less and the pollution less. Miles per gallon (mpg) is a common measure of the efficiency of a motor vehicle. It is useful in comparing different models. If the car was 100% efficient (which it can't be - Third law of thermodynamics) we could achieve about 110 miles per gallon in a normal size (and normal mass) vehicle. Recall that diesel has more energy in a gallon than gasoline and that modern diesel cars can go 50 miles on a gallon! This means less greenhouse gas emissions and aids in reducing the growing dependence on foreign oil imports. See why fuel economy is important. [143]
Do you own a car? If not you are one of the few! About 8 in 10 Americans own a car. It is another example how energy use is entrenched in the American way of life. China might have 50 cars per 1,000 people. Much of the issue still remains that in many countries the automobile will be concentrated in the cities and there are very few in the countryside.
The American dream looks like this to much of the world: Even the lower wage-earners in our culture expects a big screen TV, a computer, their own home, and of course, at least one of the classic American symbols: a motor vehicle the size of a small yacht.
To prevent the masses from purchasing automobiles that are very energy inefficient there is a gas guzzler law. So if you purchase a vehicle with mpg below a certain value there is a special tax of $1,000 (which increases as the mpg decreases below the standard of 22.4 mpg) that you pay when you purchase the new vehicle. That is very much the American way: pollution is okay if you can afford it! Or if you were to look at the other side of the issue: the money is used to give tax breaks to those purchasing energy efficient vehicles then it does not seem so bad. An interesting issue? Finally, we are now in the process of raising the vehicle efficiency standards (CAFE standards) to tackle energy security and climate change.
In other nations, you are more likely to find higher occupancy in the vehicles. In Greece, for example, the occupancy is close to 5. Here is the US it is a tad over 1! By carpooling, the increase mass for the trip is small even as the cars are already very heavy. The new (2002) Corolla is 2,500 lbs so my 230 lb addition is about 10% increase in the mass. Lowering the weight of vehicles has already been discussed but weight savings (here) can significantly increase the mpg. In Washington DC and other locations, there are high occupancy vehicle lanes (LA has had then for almost 20 years-I know because I watched Chips). In DC a high occupancy vehicle contains 2 people! The situation is worse in Europe where the cities were built and designed (if there was a design) well before the automobile. For example in my hometown of Chester, the roads go through or over the Roman Wall that surrounds the city.
The European cars tend to be smaller for 3 reasons:
Take a look at the smart car, popular in Europe, there are even a few on campus and about town. How would you like to drive one of these babies [145](check out the movie!)?
It is similar with the Japanese/Asian cars that tend to be much smaller because they will be going to highly congested major cities with limited parking.
Have a look at these two pages from the Office of Energy Efficiency and Renewable Energy.
We have already discussed some of the methods for reducing the emissions from automobiles, and will revisit this topic in more detail in Unit 3 where we discuss pollution and pollution control. Another approach to reducing emissions is the changing the fuel, with the intent of yielding better performance, and reduced emissions.
What happened to all the lead: Text Version (click to reveal)
Dr. Mathews: I can recall in the late seventies, friends of my parents coming to visit us. And they are an American couple and they brought their own car from America. And they were doing the grand European tour. Which is fine because the rest of Europe drives on the wrong side of the road just like you Americans. And there was plenty of unleaded gasoline in Europe as well. But in England, and the whole UK, the issue was a navigation one, you had to travel about 300 miles before you would find another unleaded gasoline station. And so rather than plan a normal trip where you would plan on seeing all the major cities like London, Chester, York, Whales, and the Lake District, they had to do the same kind of trip but planning to hit all the unleaded gasoline stations on the way to fill up. This is in the late 1970s and unleaded gasoline hadn't really started yet in the UK and so it was a major problem. I see very similar issues now if I was to go buy a natural gas power vehicle or even an electric vehicle. I would have to plan my trips very carefully so I could stop at a place where I could recharge or fill up. It is an interesting comparison.
Lead (chemical symbol Pb, for Plumbum) was added to gasoline in the 1920's as an octane booster, and in some cases, to provide lubrication for the exhaust values. There are 2 problems with this approach (the addition of tetraethyl lead) - the first is that the gasoline fumes contained lead, which can enter the bloodstream. Indeed, studies have found that in city children, higher concentrations of Pb were discovered, where low levels of lead in the blood of small children can reduce brain development. (Perhaps this explains my reduced mental capacity? - Na I was a country boy, so it had to have been the cow that kicked me in the head!) The second issue is that while lead was in the exhaust gases, any attempt to use catalytic converters would be thwarted. The lead covers the catalyst, rendering it useless.
But not all the news is bad: the fix to this problem is relatively easy. Simply stop adding tetraethyl lead to gasoline, which is what the US did beginning in the 1970's, Some classic cars, however, did not fair well on unleaded gas, and so they could continue to use leaded gasoline. The former USSR, for instance, and other areas with less modern technology, continue to use leaded gas.
87, 91 or 93?
In America these are the common choices when we go to fill up. In Europe they often sell higher octane value gasoline.
These refer to the octane number of the fuel, and unless you own a high-performance car, 87 is just fine! Just what is Octane [149]
What is Octane Text Version (click to reveal)
[Video opens with Dr. Mathews standing in front of a large machine.] Dr. Mathews: I am here at the energy institute research facility. To my left is an octane rating engine. When you go to buy gasoline from the garage you have a choice of several octanes. Most of you will be buying 87. Iso octane, the octane number, is based on a mixture of iso octane and heptane. When you are buying an 87 octane gasoline, what it means is it will have the same knocking behavior as 87 percent iso octane and 13 percent heptane. The way that is tested is in a device exactly the same as this. What we will do is take an 87 percent mixture of iso octane, a 13 percent of heptane and blend them together, and see how they behave in certain conditions in this particular engine. Then we will compare it with a complex blended mixture of gasoline. Remember gasoline is going to contain hundreds of different compounds. So you are not buying octane, you're not buying iso octane, and you are not buying heptane. They might be there in small quantities but they are not a majority of the components. What we are looking at is knocking behavior. If we get that undesirable, spontaneous combustion when we compress the cylinders and the gasses and the fuel in the air, and it self-ignites, that is called knocking. That is completely undesirable in a gasoline engine but it is exactly how a diesel engine works. [Video ends]
We assign iso-octane an octane value of 100 and heptane an octane value of 0. When we mix the 2 liquid fuels, we can produce a fuel with knocking properties between 0 and 100. When you purchase an 87-octane gasoline it has the same knocking properties as a mixture of 87% octane and 13% heptane (octane number of zero). It does not imply that the composition of the gasoline is 87% "octane". Gasoline might well contain over 100 different compounds. The (R+M/2) you see on the gasoline pump indicates that the knocking is averaged between two engine conditions (one more stressful on the engine than the other).
The octane number relates to the knocking (premature ignition) of the fuel. When we compress the fuel the temperature of the fuel increases (opposite of our refrigerator) and it can self-ignite before the spark-plug fires. This is a desirable effect in diesel engines, as they do not have spark plugs (which is why radio astronomers drive diesel cars - no spark plugs to give off radio signals). This self-ignition property is known as knocking. It is related to the chemistry (don't panic) of the fuel.
The combustion of the gasoline occurs because of the appropriate mixing of a vapor of the gasoline with air and a spark provided by the spark plug (see left). The battery in the car provides the electricity to create the spark; it is also used to run the radio, lights, and to start the starter motor to start the gasoline motor. The motor needs to turn over so the piston rises in the cylinder, compressing the air and gasoline mixture, which is ignited by the spark. Timing of these events is very important, hence the need for a timing belt. The resulting combustion produces hot gases, which drives the piston down providing the energy to run your car. The starter motor has started the engine and now is no longer needed, until next time.
At left is a static 3-d model of an iso-octane molecule.
The octane that we know from filling our tanks is actually 2, 2, 4 trimethyl pentane (can you see five carbons in a line-that is the pentane part, tri means three (methyls) and methyl is one carbon with 3 hydrogen's, you should be able to find three of them, can you? The molecular formula is C8H18. Can you determine the molecular weight? (Hint: each carbon has 12 amu and H 1 amu (atomic mass units). This is an example of an alkane.
When we stopped adding tetraethyl lead we needed to have a replacement octane booster and MTBE was what we chose. Chemically it is methyl tertiary butyl ether.
Can you see the lone oxygen atom? Also notice the highly branched shape that is responsible for higher octane numbers than straight chain compounds. It is the property of the oxygen atom that has resulted in additional uses for MTBE in gasoline to reduce pollution. We'll cover this more in Unit 3, where the discussion shifts to pollution and environmental consequences, this is the condensed version.
This is a product of incomplete combustion (not enough oxygen and mixing). It is a lethal, odorless, and colorless gas. The hemoglobin in your blood usually carries oxygen to your cells and removes carbon dioxide. But it would rather "hang out" with carbon monoxide. So if there is enough CO in the air it bonds with hemoglobin and the oxygen does not get delivered to your cells and you die. This is why running engines in enclosed spaces, like garages, is a bad, or fatal, idea.
The oxygen in the MTBE permits better mixing of oxygen and fuel and so there is less CO produced. Normally, your catalytic converter can deal with CO to reduce the concentration (it does not remove all the CO from the exhaust gases) but it only does so when hot. In the winter the catalytic converter takes a while to warm up and so we add MTBE during the winter months. CO in the atmosphere at low levels causes headaches and reduced mental capacity. "Health threats are most serious for those who suffer from cardiovascular disease, particularly those with angina or peripheral vascular disease." Source: EPA
Smog is also a health issue in many major cities because that is where the cars are located (and electricity generation, etc). It is a summer issue for the US as smog formation (Smog is a secondary pollutant-meaning we do not release smog but it is formed from primary pollutants or pollutants that we do release) requires: warm temperatures, sunlight, hydrocarbons (such as unburned fuel), and NOx. The presence of MTBE in gasoline lowers the temperature of combustion, which lowers the formation of NOx. MTBE in the fuel provides better oxygen fuel mixing and so fewer hydrocarbon emissions. So the combination of less NOx, and less hydrocarbons = less ozone which is the main component of smog. Much more on "smog" issues in Lesson 09.
So MTBE is great, right? Not exactly - there is one problem.
The oxygen also makes MTBE soluble in water. It is a known carcinogenic at high levels but at very low levels (parts per billion) it imparts a foul taste and odor to drinking water.
The MTBE had been leaking into the groundwater for years in California.
Those underground tanks, which are used to hold gasoline, leak!
We are in the process of banning its use. This makes farmers very happy, because they have the replacement for the oxygenated fuel additives - ethanol (from corn).
So far, we have looked at efficiencies, conservation, changing the fuel, and now we have come to the treatment(s) of the products of combustion before they leave the tailpipe. Therefore, in a way we have covered abatement: before you get in the car, reduction strategies while driving, and now hot-gas cleanup while the engine is running. Recall that we have already discussed the issue with lead, now we need to discuss the catalytic converter.
We are required by law to have catalytic converters on our gasoline cars. We do not have them (yet) on diesel engines. They do "rob" the vehicle of a few horses (horsepower) and so were not particularly popular when first introduced but there are fines and penalties for those that disable their catalytic converter, so don't do it! The job of the catalytic converter is to lower the emissions of three gases: CO, NOx, and hydrocarbons (uncombusted fuel-coming out of the tailpipe, fuel escapes from other locations in the car too).
Step 1: CO → CO2 (Oxidation)
Step 2: NOx → N2 (Reduction)
Step 3: Hydrocarbons → CO2 and H2O (Oxidation)
Therefore, we have a system that can oxidize and reduce at the same time! It is a tall order, but we can do it because we use three catalysts and we operate the vehicle so the air to fuel ratio produces the correct oxygen concentrations in the flue gas. That is why we have an oxygen sensor in the car (anyone had it replaced?) We are required to have monitoring equipment so that we know the pollution control devices are working. In the more polluted parts of the country, the standard vehicle inspection also requires an emission inspection, where they monitor the emissions from the tailpipe.
The three catalysts that are used are Rhodium (Rh), Platinum (Pt), and Palladium (Pd). These are very expensive metals and so we use as little catalyst as possible. As only the surface of the catalyst is used to oxidize (or reduce) the gases, we spread it very thinly (just like marmite [150]) (text version [151]).
We are trying to achieve a high active surface area so the inside of the catalytic converter has a ceramic honeycomb-type series of channels. The actual surface is about a couple of American football fields. The catalysts are well dispersed throughout the channels.
In this diesel engine, you can see how the fuel injection process produces a fine spray that enhances the mixing of the liquid (now atomized into small droplets) and the oxygen from the air. Nitrogen from the air is also present and an unwanted side reaction is the formation of NOx. Some of the nitrogen will also be present in the fuel as well.
[Video opens with a close-up view of a diesel engine. The injector is spraying fuel.] Dr. Mathews: This is what the diesel injection process looks like. This is the top of the cylinder head. You can see the various sprays coming in the very fine atomization to enable the mixing with the air. And then if there was a cylinder in place, it would come up, compress the gases, and self-ignite the system. What you are seeing here is a number of injections of the mist. [Video ends]
In the energy diagrams above you can see that when compounds or elements react, the process is either endothermic (requires energy) or exothermic (produces energy). This is a result of the conservation of energy (First Law of thermodynamics) that we encountered in earlier lessons (remember? [152]). A common assumption is that the larger the energy gap, the quicker the reaction - but this is not the case. This delves into the realm of kinetics: the rates at which chemical reaction occurs. A reaction might be thermodynamically favorable, but the kinetics might be very slow (or very rapid). So often, the kinetics will control whether we observe a reaction or not. We have seen the equilibrium symbol already (insert equilibrium symbol) what this actually means is that the forward reaction is equal to the reverse reaction. So in the case of CO2 in the atmosphere being in equilibrium with the CO2 in the oceans, it does not mean there is no exchange taking place, that occurs all the time, it is just that as many molecules enter the atmosphere from the ocean as enter the ocean from the atmosphere.
Often there is a special excited state of the molecule or compound that needs to form before the reactions can occur. This requires that the molecule reaches an activation energy before it can complete the reaction. A catalyst works by offering an alternative route to achieving the excited state. So at the same temperature more of the gas molecules can achieve the excited energy state and so the reaction proceeds at a quicker pace. We could achieve the same results by increasing the temperature and the pressure but adding a catalyst is the lower-cost option. So, a catalyst is any material that changes the activation energy of a reaction. It can be used to slow reactions down, but mostly we use catalysts to speed reactions up.
Why does increasing the temperature increase the rate?
We use catalysts to help chemical reactions and transformations in the chemical industry and the petrochemical industry all the time. We also have very large devices that are similar to catalytic converters to power stations to reduce NOx emissions. So catalysts are very useful in controlling emissions. More in Unit III.
Examples of some of our initial "live snippets" efforts can be viewed by clicking below the following images.
In coal, the percentage of S is between 0 and a few percent (by weight). Thus, when we burn coal, there are lbs of Sulphur dioxide (SO2) released for every million Btu's of thermal energy. We will discuss crude oil in the next lesson and will discover that like coal, the quality (and hence the value), of the oil is influenced by the S content. But the S in gasoline, at 300 PPM, is very low already. We have to remove the S from the compounds in the oil ($$$) because S is a catalyst poison. Much like the CO and hemoglobin example, S will bond with the catalyst and that portion of the catalyst surface will no longer function. We are in the process of reducing S content even lower (as California has already done) so that new catalyst technologies can be employed.
S emissions also contribute to regional haze, and to acid deposition. More in Unit III.
CATA buses are a familiar sight in and around the University Park campus and State College area. The bulk of these buses are fueled by a Pennsylvania energy source that is not crude oil. They run on natural gas (methane: probably from shale gas). Pennsylvania has both crude oil and natural gas (and of course coal). One of the natural gas fields is North of State College 50 miles or so. It is a new technology for the automotive industry (although in WWII, buses and automobiles in the UK were converted to run on natural gas when the availability of petrol and diesel was limited due to rationing). But why read about these buses, when you can see and hear me playing with them instead. Please watch the following (3:14) video:
[Video opens with Dr. Mathews behind the wheel of a Cata Bus.] Dr. Mathews: We are all pretty familiar with these Cata Busses. And you probably mostly know too that they run on natural gas. And so why many of you are interested in seeing what the front looks like, we are going to go upstairs and show you what the top looks like. Before we do that, I want you to know that this is about a three-hundred thousand dollar piece of equipment. It is a more efficient means of transportation but only if you have more than one person in it, and with me driving that is not likely to happen. Ahhhhhh! [Camera follows Dr. Mathews to the top of the Cata Bus.] Dr. Mathews: The things I do for education. Oh, bloody hell. Well, if this were a diesel engine there would be a nice tank hidden away in the bottom of the bus. With this being natural gas, what they have done is added high-pressure methane tanks to the roof; that is why the roof is slightly elevated. This is where they store enough natural gas to run for about 400 miles. Natural gas comes from about 30, 40 miles north of here in one of our own Pennsylvania natural gas fields. It is more environmentally safe, running on emissions from these vehicles is not pollution free, but it is certainly better than diesel. It is a wonderful way of using new technology to have transportation that is even cleaner than what we currently use. [Camera view changes.] Dr. Mathews: Where did the bloody camera go? Oh, there you are. What we have here are the tanks holding the natural gas used to fuel the bus. These are composite material. They are very strong. They are designed to take impacts to prevent natural gas leak. Remember it can be flammable, or an explosive gas in the right mixture with the air. To make sure we don't have any leaks, there is actually a sensor in the cab... [The sensor flashes on the screen.] Dr. Mathews: ...and if there is one, it will be detected and the bus will be evacuated. There is a lot of fear when we go to a new fuel. We are used to traveling around with highly explosive and flammable gasoline, and somewhat less so diesel. But there is certainly a fear when you go to the gases. But these are compressed so they can hold much more gas and these cylinders here are enough to give a range of 400 or so miles. This is enough so the bus can drive around town and only get filled up but once at night. A splendid situation. [Camera view shows the back of the bus back at ground level.] Dr. Mathews: We have been inside, on top, in front, now we are going to be at the back. Let's take a look to see what is under the hood of this puppy. It is a relatively standard engine. You don't need to make many changes to make this run on natural gas, although this one was built from scratch. Running natural gas is a very nice fuel for the engine. It actually creates less wear for the engine. Do you know how you change your oil in your regular car? You put in this nice golden syrupy colored oil, and when it comes out it is jet black. That is particulates. This is not going to form that so the lifetime of this engine should be longer than the lifetime of a diesel engine. [Video ends with Dr. Mathews walking away from the bus.]
These buses are cleaner than the old diesel fleet that the buses replaced. They are not pollution free. The methane can be cleaned to remove S and other contaminants but the combustion process will still produce NOx and perhaps some CH4 emissions (methane is a greenhouse gas). The fuel switching approach is yet another method of reducing emissions (perhaps–it depends on the emission). But there are fuel choices other than diesel and gasoline. Methane is another example of an alternative fuel for vehicles.
Other alternative fuels, which we'll encounter in one form or another, might include hydrogen, methanol, electricity, biodiesel, and ethanol.
By now you should have a good grasp that traditional transportation causes pollution. There is also a supply issue with the source of the gasoline and diesel. We now produce nearly all of our own crude oil. But that is new. We had traditionally been reliant on foreign imports. This is why this unit contains the security lecture (Gulf War?) Now the main driving force is pollution control.
We can use alternative fuels to achieve reduced (or elimination) pollution and enhanced national security and balance of trade. They can be encouraged by using mandates such as renewable portfolio standards (x% of the diesel sold will be biodiesel for example) or by using feed-in tariffs (the fist X5 of biodiesel will get this high price). There are a variety of fuels to choose from:
Ethanol is a chemical compound we have already discussed as an oxygenate to reduce pollution from gasoline. But it can also be a fuel in its own right. You know ethanol as alcohol. The same compound is in beer and wine and is responsible for the intoxication effects.
The CH3CH2OH formula is important. If you drink enough methanol CH3OH, your retina will detach and you go blind (all because a CH2 is missing). The OH (that is the alcohol unit) also enables ethanol to be a liquid at the same conditions that ethane (CH3-CH3) is a gas. The liquid fuels are easier to handle and store than the gas version. Which is easier to carry: a gasoline container or a pressurized propane tank? You also need to know there is far more energy in the gasoline–if comparing similar volumes. This is one of the major problems with gaseous fuels - storage has to be in pressurized containers, which increases the mass. Why is mass important? And it increases the cost (thick steel is more expensive.)
Ethanol is a biomass fuel. This means that we can grow the energy without being required to import crude oil. There are many states where we can grow corn, and this would help employment in agriculture, particularly in the "corn belt" of the mid-West. It is also used for animal feed and its use as a fuel source means pork prices goes up. This is a problem for countries with large poor populations such as South America (there have been corn tortilla riots!) The greenhouse gas savings are also in question.
There are other ways of producing ethanol, it need not just be from corn. In warmer climates, sugarcane would be the appropriate choice. In Brazil, they grow sugarcane and use it to produce ethanol. The ethanol is used in an ethanol and gasoline mixture (97 % ethanol) to fuel their vehicles.
Why do Brazilians add gasoline to the mixture? [155]
There is only one good reason to add gasoline to perfectly good ethanol and that is to render it undrinkable. Pure ethanol is essentially drinkable. It's actually not very good for you. I've certainly handled restricted compounds in my career as a chemist and I have to follow the same rules and regulations, pretty much, for 96% ethanol as I did for 99.99% cocaine. That's in pure levels of course. But it is one of these things that you do not want the population literally drunk driving while their cars have been drinking as well. You can just imagine a situation where with one very long straw, drunk driving comes to a whole new level of incompetence. So essentially the 3% gasoline is simply to stop it from being one for you, one for me, one for you, one for me at the pump.
[Video opens with Dr. Mathews standing in front of a cornfield.] Dr. Mathews: The nice thing about biomass, of course, is that it recycles carbon dioxide back into the atmosphere. This is corn. Although most of it is used for animal feed, they are associated with a great deal with food. The other thing you could do with it is either take this corn and directly burn it or you could distill it into alcohol and use that alcohol as a transportation fuel. [Video ends.]
The use of a liquid fuel has major advantages because the infrastructure is in place already. We may have to change the hoses on the pumps or else some of the liquid fuels will dissolve them, but these issues are minor.
We have seen natural gas in CATA buses and in some of the OPP (Office of Physical Plant) trucks that park on the pavement (sidewalk) around campus. The average automobile can be converted to run on compressed natural gas (CNG) for about $2,000 so it is not cheap. There is less wear on the engine and less maintenance is needed. Most of our methane is domestic and there is the potential for making more via synthesis gas chemistry. Methane is a greenhouse gas, (more in Lesson 11 on that issue) and the cost of methane can vary with seasonal demand (as does gasoline). If methane was cheaper (for the same mileage) I think more of us would be using it as a fuel. All the alternatives are more expensive than gasoline. This is now popular with fleet vehicles.
Missing from this listing are electric vehicles and biodiesel. Propane is also a potential fuel that is being used in some fleet vehicles. More on this later.
As with previous coverage maps, this map is a summary of the lesson (mouseover the boxes). When finished take the L05 quiz. This is interactive so move your mouse over the topics.
Accessible Version (word document) [156]
After looking at this map, please take the L05 quiz.
You drive up to the station, get gas (gasoline), pay for it (hopefully), and you're on your way. That's generally all the thinking we do about our gasoline supply, except when we're faced with price increases, which then sparks complaining. If you've pumped petrol (gasoline) in Europe, however, your fuel costs will be much greater. We wait until Lesson 8 to think about war/security issues that can also cause drastic price increases. Please watch the following introductory (0:33) video.
Transcript [Dr. Mathews parked his car at a gas station. He gets out of his car and walks over to the pump. As he is talking he puts the pump into the car's fuel hole, fills the tank, and replaces the pump to its holster.] Dr. Mathews: Today we are going to be talking about how we transform crude oil into the useful products we use. Mainly gasoline, as well as jet fuel, petroleum coke. Even medicines, plastics, and cosmetics. We use an awful lot of things in transforming this. There is a lot of requirements too: it has to be environmentally benign, it needs to be environmentally friendly, and of course, it has to make a profit for the industry, too. [Video ends]
This lesson covers what happens to crude oil between the time it gets pumped out of the ground and the time you use it as gasoline. We will look at the transformation of crude oil to gasoline, and the many other products that you use every day, probably without any knowledge that they came from the same source as gasoline.
Question: Do you agree that we should export crude oil to other nations?
Yes
No
ANSWER:
A few years ago this was a question about importing crude oil. We still import but are now a net exporter (how things change). The prosperity of the nation currently requires crude oil as it still powers transportation. As you will see we now are producing more domestic oil and natural gas production. We also produce alternative fuels as well. Tie that in with efficiency improvements in automobiles and we have more oil than we need. We do still import crude oil from Canada, select areas of the Middle East and other nations.
Crude oil is a highly variant natural resource. The quality ranges are similar to coal and depending on the maturation of the crude the quality can be high or low (younger crude's are of lower quality). One of the first indications of quality is color. The variations in oil color can be dramatic, and very indicative of the quality of that crude. Not all crude oil is black - higher quality oils can be golden or amber in color.
All the quality measures here are based on the ability to produce the desired products. In the U.S., about 50% of the oil is converted into gasoline. So an oil that produces a higher % of gasoline "cuts" is more desirable and have a higher quality oil. Take note, we have used much of the higher quality crude oil already! Now we need to use the lower quality oils too and the general trend is to use increasingly lower quality crudes. This quality reduction has an impact on how we refine the crude into the desired products.
Viscosity is the resistance to flow. Do not use the term "Thickness" which is a length measurement. The higher the viscosity the slower the liquid will flow and the lower the quality. We have many techniques for measuring viscosity, some of which are quite high-tech. Here is one of the simplest, utilizing one of the testing devices in one of our petroleum labs over in Hosler. Please watch the following (2:41) video.
[Video opens with Dr. Mathews standing with a viscometer.] Dr. Mathews: This is a Saybolt Viscometer. There are an awful large number of ways to measure viscosity. This is perhaps one of the simplest. I am going to pour this into a heated reservoir. [Dr. Mathews pours a beaker of Pennsylvania Crude Oil into the machine.] Dr. Mathews: And do the same with the other crude oil. [Dr. Mathews pours a beaker of Gulf of Mexico crude oil into the machine.] Dr. Mathews: The reason the reservoir is heated is because the temperature is a factor that influences viscosity. And now I am going to do a very simple experiment. What I am going to do is yank these chains and we are going to see how long of a time difference it is between the Pennsylvania crude on the left and the Gulf of Mexico crude on the right, to see how much more viscous the Gulf of Mexico crude is. So here we go. [Dr. Mathews pulls two chains which allow the oil to flow through the machine and starts a timer.] Dr. Mathews: As you can see the Pennsylvania crude oil, the higher quality crude oil, the old deep crude oil, is flowing out very rapidly. There is the same quantity in each reservoir and they are at the same temperature. Whereas the Gulf of Mexico, the blacker of the crude oils, is taking much longer to come out. Again, a very easy determination of the quality of the crude oil is the viscosity. [The Pennsylvania crude oil has finished flowing out of the machine.] Forty-two seconds for the Pennsylvania crude, and we are going to be here for a while for the Gulf of Mexico. [The Jeopardy theme plays as we wait for the Gulf of Mexico crude to finish flowing out. Dr. Mathews shows the stopwatch every once in a while. It ends at three minutes and seventeen seconds.] [Video ends.]
The viscosity process is a measure of quality because the chemical structure of the crude influences its flowability. Longer chain molecules, for example, are harder to flow than short chains because of non-bonding interactions. If you have had any chemistry you will recall ionic (type of bonding in salt crystals) and covalent bonding (the type of bonding between 2 carbon atoms). Those are bonding interactions. There are several non-bonding interactions that occur which attract (and repel) molecules. It is the relative strength of these non-bonding interactions that influence the resistance to flow.
For coal, we used the correct terminology, which was ultimate analysis. For crude, that terminology we use is Elemental Analysis. Crude oil is complex, it contains C, H, N, S, O, and metals too. But the bulk of the composition is C and H, the rest being the N, S, O, and metals. S is a good indication of the quality of the crude because as the oil is heated underground the weak S-C bond can break, producing H2S (hydrogen sulfide gas). So, older crudes - higher quality - will have lower S content. Higher S crudes also cost more to process as S is a catalyst poison it has to be removed or the extensive catalysts used in the petrochemical industry would be damaged, as would your catalytic converter. The atomic H/C ratio is also an indicator of quality (why?)
Element | Percentage |
---|---|
Carbon | 84 - 87% |
Hydrogen | 11 - 14% |
Sulphur | 0 - 6% |
Nitrogen | 0 - 1% |
Oxygen | 0 - 2% |
Hydrocarbons are molecules that contain only the elements of carbon and hydrogen. These are the bulk of the crude oil. We find 4 types of chemical structures of hydrocarbon in crude oil:
We have seen normal (for example n-heptane [157]) and branched (2,2,4 iso-octane) examples of the paraffins. They all have the same formula: CnH2n+2 (n is the number of carbon atoms). For example, in the cetane molecule above, to determine the molecular weight (Mw) you can count the carbons (x 12 the amu of a carbon atom) and count the hydrogen atoms (x 1 amu) and add the numbers together to obtain the molecular weight. Or you can use the formula:
Cetane has 16 carbon atoms (but if we used decane you would know how many carbons it contained, right?) so C16H(2 x 16)+2 OR C16H34 and the Mw is = (12 x 16) + (1 x 34) = 226 amu (atomic mass units).
The paraffins are the desired contents of the crude oil. Long chains (> 60 carbon atoms are wax) used to be used extensively for the production of candles. Now we use the shorter chains produce gasoline, diesel and jet fuel (and many other products). Note that each molecule might have many structural isomers, for example, a molecule containing 10 carbon atoms has 75 structural isomers. If an isomer is an unfamiliar term to you, I'd suggest looking it up online.
Aromatics are found in both crude oil and coal. In crude oil they are now undesirable because of soot production during combustion.
I took the soot picture above with a scanning electron microscope so we can see the very small (>1 micron) spherical soot particles. These spheres join together to form chains of spheres. To give you some idea of the scale: 80 microns is about the width of human hair. Take note that the aromatics have a much lower H/C ratio than the paraffins. The benzene ring contains double bonds (not shown). Aromatics can exist in complex structures containing many rings. The non-bonding interaction between these rings is strong and so pure compounds of 3 rings are solid at room temperature. The equivalent normal paraffin is a viscous liquid under the same conditions.
These are cyclo-paraffins and the example of cyclohexane above looks like a benzene molecule. There are no double bonds within the ring and so every carbon (in this example) has 2 hydrogen atoms bonded to it. Cyclohexane has an interesting boat or chair configuration. Can you see the differences?
In a similar manner to coal, as the source rock is buried deeper, the temperature increases with increasing depth. Thus, looking at quality indicators allows for a classification system similar to that of coal rank.
Because "old deep" oil provides the highest quantity of gasoline, it is the higher quality crude oil.
Most graphs you are used to seeing or plotting have just 2 axes. This works fine if you're just comparing 2 components, but as you see below, we're comparing 3 general classifications for crude oil compound types. It is the ratio of these compound types (aromatics, paraffins, and naphthenes) that impacts the quality of the crude (in addition to S content, especially when the S is within the aromatic portion, which makes it much harder to remove during refining). So, to plot 3 items on a single graph we use ternary diagrams like the one you see above. At the three apexes, the composition would either be pure (100%) aromatics, pure naphthenes, or pure paraffins (clockwise from top). Along any of the borderlines of this triangle, you're looking at a mixture of just 2 of these components (aromatics – naphthenes or naphthenenes, paraffins or paraffins - aromatics). At any point within the triangle, the crude contains all three components, in varying degrees.
Take the example of 50% aromatics to begin with. To plot this point on the graph, you'd create a drop a horizontal line about halfway between the apex (100 %) and the base of the triangle opposite of that apex (0%), representing 50%. You repeat this process to locate the other %'s of the compound types on the graph, and the point you're after is the convergence of those three lines. Thus, the center of the triangle is: 33%, 33%, and 33% of aromatics, naphthalenes, and paraffins– crude oil that would generally fall into the "old shallow" classification. Here is a dynamic example [158].
We move crude oil and the finished products (gasoline for example) via a variety of methods: pipeline, tanker, and the multi-wheeled big (trucking) rigs. We are concerned that the transportation be performed safely, and without spillage.
By far the best method of transporting a fluid is by a pipeline. Some of these pipelines are very long, such as the 800-mile Trans-Alaskan pipeline, which carries 17% of the domestic production of crude oil. These pipelines are expensive, however, a cost of $8 billion at 1977 rates! The pipeline is cleaned periodically with "pigs" (which are mechanical devices that can travel inside the pipe to remove any wax buildup from the inside of the wall - other pigs check for corrosion etc.) Perhaps we will build a new pipeline (go and take a quick look at this project: Keystone [159]) to bring an improved (upgraded) tar sand obtained crude oil from Canada all the way to Texas.
Keeping these pipelines functioning properly [160] is no small feat.
Unfortunately, the pipeline ends in Valdez (because it is a relatively deep port, good for tankers, and is free of ice most of the year). Thus, to get the Alaskan crude oil from the state of Alaska to the markets in the rest of the United States requires tankers to carry the fuel the ocean leg of the journey. Generally, this is to the refinery operations on the West Coast (we in the North East get our crude oil from exotic locations such a Nigeria, Saudi Arabia, Venezuela, etc but also from even more exotic locations such as Warren, or Oil City, etc. in Pennsylvania! In 1989 the Exxon Valdez ran aground leaking 11 million gallons of crude oil. This was the worst spill in US history; it resulted in legislation that addressed the transportation of crude oil into US territorial waters (more on the Oil Pollution Act of 1990, later in the lecture).
The US produces a great quantity of crude oil (but it provides only about 55 % of our needs). Our production is only exceeded by that of Russia and Saudi Arabia (normally we are 2nd). Much of it arrives in the country via tanker. Those tankers operating in US territorial waters now need to be double hulled (by 2015) as a strategy to reduce large oil spills. Remember these tankers can be huge.
There are only a few travel "lanes" for the international trade of crude oil. Much of the transportation is via tanker or via pipelines (The World is not Enough-James Bond Movie, splendid). This has major security implications for the safe delivery of a very valuable commodity. The map below shows the important oil flow bottlenecks.
It is not just transportation of crude oil, or its products, but storage also. We produce (extract) a lot of oil, and we also store a lot of oil and crude oil products. Safety is a concern around all the flammable liquids. Spills inland can be just a devastating as those affecting the coastline. Regulations also require that the retaining walls, which surround the tank, are sufficient to retain the liquid in the event of a failure.
What you don't see in the image is that the tanks are in a very large depression in the ground (a bit like an empty swimming pool). Should the tanks break, the oil would be retained in the "swimming pool" by the retaining walls.
Oil products have also been leaking into the ground from the storage of gasoline at gasoline stations. Recall the MTBE issues. When you buy a house one of the things the homeowners have to reveal is if there is a storage tank on the property. It is not good news if there is one, as often they need to be removed. You also accept liability if it does leak at a later date.
Road crashes also leak crude oil products like gasoline. The fire trucks carry long buoyant absorbent socks (similar to booms) to prevent gasoline and diesel spills from further contaminating the waterways.
The influence of any spill on the surrounding wildlife depends on the nature and the size of the spill, as well as the ability of the wildlife to avoid the area. Gasoline, for example, will eventually evaporate; diesel and most of the other fuel oils, however, will not evaporate completely.
Oil will seep to the surface and form tar pits, or on the ocean form a small oil slick. These events are natural and occur every day. However, we move large quantities of crude oil and nearly as much in various products (gasoline, jet fuel, etc.) Some spillage due to transportation is going to occur. When it does there are different approaches to cleaning the spill. It comes down to three general approaches: Contain and remove, disperse with chemicals, or do nothing (it will eventually disperse). There are also "spills" as a result of war (First Gulf War), and from drilling, notable the Gulf of Mexico drilling disaster associated with BP's Deepwater Horizon operation [161]. Here is a good article on the relief well that finally stopped the spill. [162] After reading this page you should know how spills are treated and prevented.
The role of the refinery is very simple. Make a profit for the shareholders and produce an environmentally responsible product.
The method of making a profit is to carefully follow the supply and demand curve for their products.
Products from a refinery are the obvious: gasoline (46%), diesel, jet fuel, & fuel oil and the less obvious (to some of us): asphalt, coke (for the aluminum, iron, and steel industries), chemicals, plastics, & lubricants (including motor oil).
The demand for these products will be dependent on the weather (fuel oil), economy, driving habits (Americans are driving further, and more in the summer), military conflict (jet fuel, etc during the Gulf war and other conflicts), and other suppliers. The quality that a barrel of crude oil produces will also be dependent on the quality of the crude oil, which can be highly variable.
The first thing to do is clean up the crude oil and take out the water from the oil. An interesting feature of this water contamination is that it contains salt. This is a very corrosive liquid (salt water) and needs to be removed prior to any other processing steps.
Distillation is the heart of the refinery operation. It is the location where the crude oil is separated into many "cuts". Often the distillation tower is very noticeable, as it tends to be one of the taller structures at the refinery. The crude oil is separated into certain "cuts" depending on the volatility of the compounds. This occurs as a continual process: crude oil arrives, is stored and sent for separation via the distillation tower. The cuts are blended, or altered to increase the quality or the quantity of the more desirable products.
Crude oil is very complex. Some crude oils will contain over 1,000,000 separate compounds. Different isomers, length molecules, sized molecules will be present. It is very difficult and expensive to separate the compounds into pure cuts, so we don't even try. We are content to separate the molecules into an initial series of cuts.
Do you know what factors influence the desirability of different products [164]?
Below is a very simplified view of the distillation process. If you find that this topic keenly interests you, then you should consider the 3 credit, 400-level class our department offers just on this subject alone. The processes and products are explained in more detail below the image! Place your mouse over the green text on the image for more information.
The crude oil is heated before entering the distillation tower. In the tower, the more volatile compounds will turn into gases and flow up the tower, and those compounds that have higher volatilization temperatures will remain behind and get hotter. Thus, the top of the tower will have the lower temperatures and the compounds that have the lower boiling points (temperatures). The bottom of the tower will have the less volatile compounds and have the hotter temperature. To ensure good separation there are lots of stages (also called trays) that the volatile compounds may pass on the way up the tower. When the volatiles are cool enough they will turn back into the liquid form. It is the liquid in the trays that will make up the initial cut. A better quality crude oil will yield more of the lighter cuts than the denser cuts. Unfortunately, even the good quality crude oils will not give a 45% gasoline cut from the crude oil which is what is desired (average for the year), thus other processing steps are required to increase the yield. As always, "How stuff works [165]" provides more good information on this topic.
Some refineries will also operate a vacuum distillation unit to increase the more useful products from the remnants of the atmospheric distillation tower. By lowering the pressure it becomes easier for certain compounds to enter the vapor stage at lower temperatures.
Often the gasoline fraction produced by the initial cut in the distillation tower will not be of sufficient quantity or quality for the market and so chemical processing is required to increase the product yield and to ensure appropriate quality and compliance with environmental regulations (which in turn is dependent on market and country location; California, for example, has more stringent requirements than central Pennsylvania).
In the past, the longer chain molecules were highly prized for the production of waxes, and while they're still prized for specialty lubricants, the market is not as large as the gasoline market, so some of the long chain molecules will be "cracked" to produce the smaller molecules that are of appropriate length for gasoline production.
This cracking can be achieved through high temperatures and high pressures or through combined catalysts and temperatures with high pressures. The "ends" of the molecule require capping hydrogen atoms so to achieve this one fragment forms a carbon to carbon double bond that we chemists call an alkene (we call paraffin alkanes).
Gasoline quality is often indicated by the octane number. 2,2,4-trimethylpentane is assigned an octane number of 100 (it contains 8 carbons hence the name "iso" octane, compounds can have octane numbers higher than 100), heptane an octane number of 0. The octane number of gasoline indicates the fuel has the same combustion performance in an engine as a certain blend of 2,2,4-trimethylpentane and heptane (i.e., an octane value of 80 has fuel characteristics similar to a blend of 80% 2,2,4-trimethylpentane and 20% heptane). The higher the octane number the less likely the fuel is to "knock", i.e. buying a higher octane number gasoline indicates a better quality fuel.
Lead (tetraethyl lead to be precise) [166]
As you'll recall from Lesson 5, was also used as an octane enhancer but has been banned from most of our gasoline back in 1970.
The quality of the gasoline can be increased by reforming, which is either altering the shape (isomerisation) or altering the composition of the molecules. Essentially, the quality of gasoline can be increased by increasing the branched chain producing higher octane numbers.
Click on the image below to open The American Petroleum Institutes Refining portion of "Adventures in Energy". Go through all of the Refining Oil pages.
Mouseover the content for more information. When finished here complete the L06 quiz.
Accessible Version (word document) [168]
After looking at this map, please take the L06 quiz.
Many people think of Texas when they think of gushing oil and drilling rigs, but Titusville, PA., in the northwestern part of the state, lays claim to the first operational oil well in this country. So, the oil industry has its roots very much in our backyard.
Thus, this lesson deals with the origins of oil and natural gas. Please watch the following (0:35) introductory video:
[Dr. Mathews is standing in front of a nodding donkey (oil pump) on a cold and rainy day.] Dr. Mathews: Today's lecture is obviously about crude oil. I am just south of Pittsburgh. It is bloody cold. But this is a prime area for producing Pennsylvania’s lifeblood, crude oil, and natural gas. This one behind me is pumping, so it's probably not flowing out of the ground anymore so there is probably not any associated natural gas. [Dr. Mathews walks off the scene and we are left looking at the oil pump.] [Video ends]
Your learning objectives for this lesson:
Question: Are fossil fuels beneficial to Pennsylvania?
Click for the answer.
Often when we find crude oil we also find associated natural gas. The natural gas provides much of the pressure to produce the "blow-outs" that in good old days (and in the movies) signified an oil strike. We can also find natural gas alone without crude oil. The gas has migrated away from the crude oil, or perhaps the oil has "seen" a high enough temperature that it has all been converted into natural gas.
As organic material decays, methane is formed and lost into the atmosphere. As the organic material breaks down, depending on the inputs (trees vs. plankton), the different fossil fuels will form. As the material is buried deeper the temperature increases and there is an "oil window", or an opportunity to find oil. If the temperature is too high then all the crude oil will form natural gas instead, and so the oil window closes. Of course, we also find oil at the surface, but this tends to be degraded oil that has lost the more volatile components and so tends to be tar pits (not pools of crude oil).
The phytoplanktons [170] are numerous in the ocean and are a very significant portion of the carbon on the earth. They live in water near the surface during life and use the solar energy in a similar manner to plants on land to store chemical energy. They tend to be concentrated in nutrient-rich zones. As the first link in the ocean food chain, they are eaten in large quantities.
Upon death they sink to the bottom of the ocean where the decay process occurs. Think back to all the deep-sea footage you have seen where is it "raining" organic matter. Often the nutrient-rich zones are also locations by rivers that carry sediment from the land to the sea. If the dead plankton and sediments fall in quantity they will form an organic-rich layer at the bottom of the ocean. There it will be protected from aerobic decay, because of the physical protection (sediment) and the lower oxygen content.
Over long time periods, millions of years, the layers are buried deeper and deeper and the temperature builds up (as does the pressure) and the layer turns into a rock. However, it is a rock that has significant organic content. Additional time, temperature, and pressure, and the maturation process produces kerogen. Additional time and the kerogen is transformed into bitumen and then crude oil with associated methane. These materials can escape the source rock and if unchecked can seep into the surface of the ocean (or land) and decay back into carbon dioxide and water.
As the oil and natural gas move through porous rocks, if it meets an impermeable layer, then it is stuck and the maturation process continues. Thus, crude oil and gas "live" within porous rocks, not great holes in the ground (unless they are in the strategic petroleum reserve) - more on that later.
If we find these structural traps and they contain oil or gas, we can extract the fossil fuel and much of it will be combusted to generate thermal energy (for transportation or heat) and yield carbon dioxide and water.
When we extract crude oil it contains some water. However, even when we extract Pennsylvania crude oil the crude will still contain water but it is NOT often fresh water. The water contains salt and many of the other elements in concentrations that we find in the ocean. The disposal of this salt water is an expense. In the good old days, it was thrown in a river or stream but the salt would kill the fresh-water fish. Now it is cleaned prior to disposal although we hope that PennDOT and PA DEP (Department of Environmental Protection) will let us dispose of the salt water on the winter roads to prevent icing.
We also find microfossils in the source rock that indicate that the inputs to the rock contained life. However, the strongest indication is the identification of biomarkers within the crude oil.
The Porphrin ring has an important role in biology. The nitrogen atoms are blue in color and there is a metal ion (in this case vanadium) in the center of the molecule. Metals such as vanadium and nickel are present in oils at low levels but they are important contaminants. Nitrogen as shown is blue, double bonds are not indicated. This is an example of a porphrin ring a biomarker in oil. The metal sits in the central location of the rings. If catalytic cracking of the oil is performed, it is important to remove these metals as they poison the catalyst. Vanadium can be recovered from the ash or flue gas when high vanadium containing oils are combusted. The vanadium can then be sold to the metals industry for use in steel generation. Biomarkers are also useful for identifying where the crude oil is from.
As we have already seen, we use lots of crude oil. So to prevent it from running out we look for more crude oil. We can go around drilling holes but it is an expensive operation and so we only drill if we think there is a good chance of finding crude oil. Even then dry holes are not uncommon. There needs to be a certain set of circumstances for us to find trapped crude oil. Of course, oil and natural gas are finite resources so we will run out eventually.
When the zooplankton and phytoplankton died and fell to the ocean floor, sediment helped bury the organic material. Over the maturation process, the sediment is transformed into rock and we use the term source rock for this material. Finding it is a good sign that oil might be nearby. Within this rock, we can find microfossils, and along with biomarkers, it is good evidence that oil was created from organic material. The source rock indicates where the oil was when the kerogen to bitumen to crude oil transformation occurred the crude can escape the source rock. So now the challenge is to find where it might have gone.
The crude oil and natural gas can travel through porous rocks. If there is nothing to stop it, then the crude oil will reach the surface and eventually degrade (recall the oil spill page - one approach to cleaning up an oil spill is to do nothing - it is a natural material and there are natural processes to destroy it, although this approach does not work well if the spill is large or close to sensitive areas!) We call these locations where we find crude oil (or natural gas) at the surface seeps. A seep is a good indication [171] of crude oil underground. However, often the material at the surface has lost the light ends (compounds with low volatility) and are not very valuable. Thus, we need to find structural traps where impervious layers prevent the crude from progressing any further. Examples of structural traps are: salt domes (the SPR is kept in large salt caverns "drilled" with water to dissolve the salt), faults, and anticline folds.
A structural trap does not do us any good unless there is a porous rock that can hold lots of crude oil. The idea that we drill down into "lakes" of crude oil is a fallacy - we drill into a porous rock and the pressure of the crude oil and associated natural gas pushes the oil out of the ground.
This PDF file provides very good information about how crude oil is found and the technologies that are utilized [172] to find and extract the crude oil. Ensure you look it over.
One thing you'll become familiar with is the use of seismology in the search for crude oil and natural gas. Below is a movie captured from a software program called the "Seismic Duck", which, via an animated sequence, shows how seismic waves are used to detect oil sources deep in the ground. If you've ever seen ultrasound technology at work, a similar principle is at work. Please watch the following (:44) video.
[Animation opens with a duck sitting on top of the earth's crust. Under the crust is a thick layer of sediment. Then there are three natural gas and oil deposits. As the animation goes on, sound waves are shown to emit from the duck and detect where the oil and natural gas is located. Once found, it is drilled into.] Dr. Mathews: When we talk about seismic waves what we are doing is setting off an explosion, or actually an air can, we don't tend to use many explosives. And it is the sound waves that propagate through the sedimentary rock, and they bounce back. And by having a whole multitude of sensors we can determine a good picture of what underlies the ground. And once we do that we have a good idea about where the structural tracks are. We can go ahead and drill down. Now in this situation, there is a porous rock shown containing water, which is the blue line. So we are going to drill down to extract the crude oil and the natural gas. You don't extract all the natural gas because it is helping push the crude oil out. And of course, at the same time, we are also getting water as well. [Animation ends]
There is a very important distinction between resources and reserves, which is illustrated in the image below.
Move your mouse over the "oil areas" to see how crude oil resources, reserves, and consumption relate to each other.
Fuel Resources are fuel formations that are known to exist but are not currently economically viable (or technologically viable).
Fuel Reserves are fuel formations (such as an oil field) known to exist, which have fuel that can be extracted economically with current technologies and price structures. When oil prices rise or there is an advance in technology (such as deep sea oil drilling or hydrofracking), then resources become reserves, etc. Of course, new oil (coal and gas fields) are still being found. They are also still being formed but the rate of formation is so slow (millions of years) we do not consider new fossil fuel formation a possibility.
So we have extracted a lot of our fossil fuel resources but there are many more available as you can see below. Unfortunately, it tends to be lower quality and more expensive to get.
The lifetime of a fossil fuel is the quantity available (reserve) divided by the consumption. So:
Lifetime of a fossil fuel = Quantity in Reserve/ Rate of use
Let's look at some numbers:
Lifetime of supply calculation:
22,446 million barrels / 1,915 million barrels per year = ~12 years
Why doesn't this worry me [173]? Audio Text Version (click to reveal)
Dr. Mathews: You would think if we only had eleven years or twelve years supply of crude oil left that we should be in a bit of a panic. But the bottom line is that we aren't. If I looked up the data from a few years ago, actually we have more crude oil than we did back then. Remember this is somewhat of a misleading calculation. Because although we do have a relatively fixed quantity of crude oil in the world, our ability to find it changes quite dramatically, in the sense that we have to be looking for it. When we have lots of reserves and the price of crude oil is low we don't look for it. When we have certain economic indicators that the value of crude oil is higher then we go and look for some more. And so it is a continually moving target. Yes, we have crude oil. Yes, we use it. But the bottom line is we do not see reductions in how much crude oil we have every year. This is because we find new crude oil. This is because of some uncertainties in the existing fields. And we tend to be able to make some adjustments and get some more out of the ground. And if you look back in the history of these estimates, even one-hundred years ago, said we had thirty years to fifteen years of a supply of crude oil. And every decade or so someone comes up with the same calculation and the same estimate and the number is about the same. So we have had about a fifteen year supply of crude oil for the last hundred years. And we are probably going to have a fifteen year supply of crude oil well into this coming century. Now certainly some of our fields are going to become exhausted. Some of the Alaskan fields, for example, are going away and in the UK, some of the North Sea fields are going to be exhausted. But essentially what we will do is look for new crude oil. We will spend additional money, we will have new technologies, we will go deeper finding it in the Gulf of Mexico, and we will be able to extract more with some additional techniques I will discuss. So yes we only have eleven point two years of crude oil supply via this calculation but the reserves are going to continue to grow and be depleted at the same time. Generally, that is going to be about the same rate. But eventually, at some point in time, the US is going to pretty much run out of its crude oil but then we are going to switch to other fuels. Remember we can take coal and turn it into a crude oil. The reason we don't do that is because it is expensive. Cost us about thirty-five dollars a barrel to that and I can go and buy a barrel of crude oil for about twenty-seven dollars. So it is cheaper but once we start running out, then the cost will go up, and we will be more able or be more intent to save money by going with some of these new advanced techniques. And of course there are tar sands, oil shale, and the list goes on.
Here is a good example of how changing technologies such as horizontal drilling and hydrofracturing have recently (2008 to 2012) increased our reserve even while our Alaskan reserves are being depleted due to extraction.
We can do a similar calculation for US natural gas:
A lifetime of supply calculation:
183,460 billion cubic feet / 19,779 billion cubic feet per year = 10 years
That equates to about a 261-year supply if we maintain coal extraction levels.
Remember, our RESOURCES of fossil fuels (those that are not economic to extract, or which would require technology we currently lack) are much larger than the reserves (that we can extract using current technologies and are economically viable).
There is only one way to tell if the location you have picked contains any oil or natural gas: drill! This is one of the most expensive parts of the extraction process and there is a lot of technology employed in selecting the location and technologies employed. In the "good old days" a wooden platform (a derrick) would have been built to enable the drilling process. Roads are often built to allow the machinery into the appropriate locations, machinery, equipment, and pipes that will be used at the site. Not to mention the storage of the crude (or natural gas) and the extraction and storage of the saltwater. The drill bit rotates and chew's into the earth. If you have seen Armageddon (Bruce Willis drilling into an asteroid) you know that drilling is both an art and a science. There is lots of friction and heat so it is necessary to cool the bit with drilling mud. In most cases, there will also be a need to enclose the circumference of the hole with pipe to stop it collapsing. As the hole gets deeper more casing is added. Eventually, there is a pipe going deep into the earth. Sensors attached to the drilling system alert the operators to when they reach the desired position and if there is any "black gold" (or natural gas or both). It is undesirable to let the oil burst out of the ground because you lose some of the reservoir pressure (that pushes the oil out of the ground). A production pipe is lowered and concrete poured to fill the gap between the production pipe and the enclosing "pipe".
Now we have a deep hole in the ground. To allow the reservoir (the oil-bearing rock) to make contact a perforation gun is used to "shoot" a hole through the production pipe. There are also techniques used to frac (short for fracture) the oil-containing rock so that production can increase the flow of oil out of the ground (recall lesson 4!). If there is associated natural gas with the oil then the oil will flow out of the ground. Unfortunately, in many of the PA wells and at other locations this does not last and the reservoir pressure drops and the remaining crude oil (that is extractable) has to be pumped out of the ground.
The horse head pumps pump the crude oil out of the ground. If you need more crude oil then drill another well, situate it close to an existing production well so you expect to find crude oil, and add another pump (horse head). In PA we have lots of these stripper wells (a well that does not produce more than 10 barrels of crude oil in a week). Being English I know these horse head pumps as "nodding donkeys".
Chemicals are added to the production pipe to try to prevent build up of deposits or wax. Remember the oil is warm and so cools on reaching the pipe. In winter or in waxy oils wax formation can plug a pipe and a pig (type of scraper) is sent down to clean the tubes. Even with good management we cannot produce large quantities of crude oil without drilling lots of wells. In PA there are about 100,000 wells that have been drilled for oil and natural gas (many now abandoned). Having said that there are locations in the world where a single well can produce 10,000s of barrels a day.
However, the quantity of crude oil coming out of the ground is a small percentage of what is in the reservoir. If we can increase our extraction efficiency resources that become reserves, our useful supply of crude oil will last longer. I like (industry) video (5 min long) for natural gas (oil extraction is very similar). Pay attention to the drilling and fracking (this is an example of a horizontal well) process. Look for good terminology to use in your exam answers!
The "natural lift" and "artificial lift" might produce 10 - 25% of the oil in the reservoir. To get any more, other techniques need to be used. Of course, these other methods include additional expenses. Many of the Middle East wells have natural lift that runs for very long periods. In the US most of our oil requires artificial lift techniques.
The saltwater produced by the well or other water (such as municipal drinking water) can be pumped down into the reservoir. The oil, being less dense than the water, floats on top and is thus forced into the well bore of the production pipe. By utilizing water flooding, perhaps an additional 10% can be obtained.
Steam or chemicals are pumped down to lower the viscosity of the crude oil and to enhance the extraction process. Of particular interest for Lesson 12 is the use of CO2 as an enhanced oil production technique.
Oil is found in many locations around the world although the high-quality crudes are not as well dispersed. The Middle East now produces almost 30% of the World's crude oil supply.
Unfortunately, the US production of crude oil is starting to be reduced and this has implications. Click on the image to see why! We are becoming (again) increasingly dependent on imported crude oil. We are starting to look and drill for crude oil in deep water and environmentally sensitive areas. Domestic production is preferred over imports only when the costs are comparable. We take cheaper crude when we can get it. Wouldn't you?
But we also need to realize that the extraction part can go wrong and cause lots of environmental damage. Take a look at these BBC pictures of the Nigeria delta. Some of the oil companies have pulled out because of safety issues, and the locals stealing oil also produces some of the problems. However, it is an environmental disaster that needs to be cleaned up. Social issues are also very important here.
Chesapeake energy has a very good 6 min video that gives a good overview of natural gas drilling [174] into shale (similar to oil drilling). Also look at the horizontal drilling and hydraulic fracturing below and "fracking" or the use of water under high pressure to fracture and stimulate the well. You don't need to know all the technical terms, just get the basics of how drilling, stimulation, and extraction occurs. These gas shales are an "unconventional resource" but provide over 10% of our natural gas production. The shale contains organic material (kerogen) that undergoes maturation and the formation of methane. Challenges here are access to large amounts of water for hydrofracking (fracking) and water cleanup (due to chemical additives and hydrocarbon contamination) while protecting the environment. Have the goal of being able to describe the process of drilling (including horizontal drilling) and fracking. Please note that this is for shale gas but also applicable for oil extraction.
We have three fossil fuel resources that can replace crude oil. They are oil sands (also formally known as tar sands), oil shale, and coal liquefaction or gasification. These are also known as non-conventional sources.
Oil sands are important because they are abundant, and Canada has large reserves that they are upgrading to form a "synthetic" crude oil. The major importer of this fuel is the US. By now, you should realize that the stages in the formation of crude oil are as follows:
Organic → Kerogen → Bitumen → Crude Oil & Natural Gas
So we will see that this is similar to the formation of oil shale. The bitumen is a viscous semisolid. It is so viscous (and often solid in cold weather) that traditional oil extraction techniques will not work. Thus, the overburden is removed, and the tar sand extracted in a similar manner to the extraction of coal from a surface mine (although I don't think they need to use explosives to break up the sand in the summer).
The origin of the oil is a controversial subject among geologists, but the predominant theory is that it evolved in highly organic Cretaceous shales in the southern portion of the Alberta Sedimentary Basin. Underground pressure forced the oil to soak into the existing silt grade sediments and localized sand bodies of the McMurray formation.
Syncrude, Canada
The bitumen forms a solid in cold weather, so the tar sands are a rock, but in summer the consistency is that of thick mud. The tar sands are either trucked to the processing plant or sent to a slurry plant, then to the processing plant via a pipeline (why?). Chemicals and heat (retorting) are used to separate the sand grains from the bitumen. The sand then goes back to reclaim the land (fills in the massive holes!), and the bitumen is refined using similar technology to that already discussed for crude oil.
The oil we're talking about extracting here is considered "heavy" oil, a term popular with the masses, but not necessarily accurate, since it refers to the oil's high density. This is in contrast to "light" oil, which is higher quality oil, and which is of lower density, yielding gasoline products more efficiently. The process of upgrading all the "heavy" oil (low H/C ratio) from the oil sands requires lots of hydrogen (usually obtained from methane and from the cooking process). The synthetic crude oil produced is sent via pipeline to refineries in Canada and the US. You might be using gasoline or products from oil sands as our closest refinery in Warren, PA uses this synthetic crude oil along with PA crude oil. The synthetic crude is rich in asphalt and so when you drive new roadways or have a new roof (asphalt shingles) you again might be using oil sand material.
This link helps explain the extraction process a bit more [175] (surface mining and some in situ extraction: drilling, steam, pumping). Goals here are to understand how surface mining and extraction of the bitumen occurs.
Canadian oil sands deposit is the world's largest. To give you some idea of how large their reserve is:
The Canadian companies extracting the bitumen can make a profit with current oil process this is economically feasible and profitable. It is also a reasonably secure energy source given that now the US and Canada are trading partners, and are friendly [176]. Text Version (click to reveal)
Dr. Mathews: Question, where is the capital of Canada? Well, it is not Toronto, it's not Montreal, and it certainly isn't Quebec. Of course, it is Ottawa. But it is a very strange choice to have the capital sort of far away from everything. And there is a good reason for that. Relationships between the United States and Canada have not always been friendly. Remember that you are a rebellious nation, you gave up the good guidance of the king and the queen, in favor of this democracy crap. And of course when you did the Canadians remained loyal. And so there was definitely a fear of an American invasion into Canada. And I forget what the statistic is, so please do not quote me on this, but it is something like, eighty percent of the Canadian populous lives within one-hundred miles of the Canadian border. You certainly couldn't pick Toronto because of the fear that it would be very easily captured. And you certainly do not want to have your capital city captured. And so the queen, in all of her wise ways, decided that she was going to place the capital of Canada in Ottawa just to be further away. And of course you wouldn't want to put it in Quebec because of the French influence. And that is where it stands. And you can go and see that is has a very similar parliament to the British system and by law, the two benches need to be at least two sword distances apart, also that is an interesting thing. But you haven't always been friendly with the Canadians.
We also can find carbonaceous rocks that contain significant organic material in the form of Kerogen (with perhaps some bitumen). The prevailing thought regarding the formation of this material is algal blooms in lakes. There is a summer (thick) layer and a thinner winter layer that dies and settles on the bottom of the lake. This created an organic-rich sediment that eventually formed a source rock. The many layers of source rock that are formed indicated that this process might have been occurring for a few million years. Thus, there is a lot of organic material in oil shales. Unfortunately, the long time periods required for crude oil formation and high temperatures have not been obtained and so we have a source rock with very immature crude oil precursor. We can mine the oil shale, crush, and retort (heat with steam) to extract the kerogen. This can then be upgraded or gasified to supply electricity. We have large quantities of oil shale in the US (large areas of the oil shale containing land, are owned by the US Navy (why?). Worldwide the 5 to 6 times the world resource of petroleum. But have you ever heard of it? Currently, it is still cheaper to purchase crude oil than to produce oil from the treatment of oil shale kerogen. The locations in the US are out West mostly within the Green River formation of Utah/Wyoming.
Recall that when South Africa was embargoed because of the Apartheid policy, they had to find an alternative to crude oil. They used coal to supply all of their chemical needs from gasoline, to fertilizer, and explosives. Similar approaches have been used in World War II in Germany (the birthplace of gasification technology), Britain, and Japan. So with gasification of coal, we can produce transport fuels, chemicals, and electricity.
Natural gas can be a valuable fuel. However, we have seen that we do not historically have a very large supply of natural gas, or do we? The reserve and resource discussion has relevance here. As we start to run out of supply (we need more than we can produce) the price increases (laws of supply and demand). As the price increases, then those resources that had marginal economic potential now have a greater potential to produce a profit and so are moved from being a resource into being a reserve. Technology also has a role to play: we can drill deeper (in our efforts to find natural gas), or go offshore. We can also look for alternative sources of methane: shale gas, coalbed methane, gas hydrates, synthesis gas generated methane, and landfill gases (methane).
The methane that was once the enemy of the coal miner can now be extracted either prior to mining, or from coal resources that are too deep to be economically mined. Currently, about 7% of the methane used in the U.S. is from coalbed methane. Recall that as the coal matures it is increasingly rich in carbon and towards the end of the bituminous stage there is a loss of hydrogen. Most of this hydrogen forms methane that may become trapped in the porous structure of the coal. Usually after mining coal, the methane escapes or the methane is released along with the ventilation air. We can recover probably about 100 Tcf (trillion cubic feet) or about a 5-year supply if it was to provide all the US consumption.
We have always had methane contained within certain coal seams. But not until methane had an increased value was it economically efficient to extract. We also needed to develop the techniques to drill into the coal seams to maximize the return of the methane. With both of these prerequisites in place (high methane cost and advanced extraction technologies), the reserve of coalbed methane has grown despite the methane being extracted (more recent dip is due to the higher value of wet shale gas (wet here meaning containing liquid hydrocarbons also).
Synthesis gas (also known as syn gas): CO and H2 is produced by the gasification reaction:
C + H20 ------> CO + H2
The carbon is generic (could be natural gas, coal, char, or any source of carbon in a carbonaceous material). Mostly, however, it will be coal, a fossil fuel that we have a lot of! Steam (or oxygen) is passed over the hot coal and gaseous products form, known as "water gas." The process is endothermic (requires heat) so energy is required to heat the coal, this could be done by coal combustion but this uses a portion of the carbon. Instead, a balance is achieved between the exothermic (heat producing) reaction of carbon and sub-stoichiometric quantity of oxygen (not enough oxygen to produce CO2):
2C + O2 -------> 2CO
and the endothermic reaction gasification reaction.
If air is used the gas has a low calorific value (100-125 Btu/scf) (SCF is standard cubic foot) and can be used as a fuel. Do you remember that nitrogen in the air dilutes the energy of combustion? If oxygen, instead of air, is used to gasify the carbonaceous material, the gas has a medium calorific value (approximately 300 Btu/scf). Or by not adding nitrogen as a dilutant we get more energy out of the synthesis gas.
The water gas is subjected to the water-gas shift reaction:
CO + H2O <-----> CO2 + H2
Which converts some of the CO to CO2 and hydrogen or vice versa. This is done to change the ratio of CO and H2, and through removal or addition of components, changes in pressure and temperature, the equilibrium can be manipulated and the ratio of water-gas components shifted to the desired ratio depending on the required products, which include substitute natural gas (SNG -methane), methanol, or gasoline.
If methane is the desired product, the cleaned gases (to avoid poisoning the catalyst) undergo the water–gas shift to change the H2 to CO ratio to 3:1 prior to the methanation step:
3 H2 + CO ----------> CH4 + H2O
and
C + 2 H2 ----> CH4
Methane hydrates are important for one reason: there is so much methane in the form of methane hydrates that it dwarfs our traditional supply. If we can only reach a small percentage of the methane hydrates we will have a vast energy source. They are found both on land (in some of the permafrost areas) and in the ocean on the seafloor.
The methane flame shown to the right is blue in color because of the CH radicals within the flame. Here a solid, ice-like hydrate is on fire; the hydrate melts, releasing more methane.
As you can see, we will be increasing the use of these non-traditional sources of natural gas, notably shale gas, tight gas, and coalbed methane (but not methane hydrates, yet!). Tight natural gas is methane from low permeability sources.
This is a very long web page (encyclopedia entry) on petroleum from the National Graphic Organization [177], but scan through it. You should recognize the technical terms and know what they mean. If you use terminology correctly in the written portion of the exam, grades will improve.
As with previous coverage maps, this page map represents a summary of the lesson, providing you with a way to quickly refresh yourself on the big ideas and connections in this lesson. This is interactive so move your mouse over the text boxes/shapes for more information. After this take the quiz.
Accessible Version (word document) [178]After looking at this map, please take the L07 quiz.
Our appetite for energy and fuel not only has significant environmental challenges but also economic and political implications. We tend to notice this only when there is a noticeable threat, crisis, or accident related to our energy access. Most of us have experienced the minor inconvenience of a neighborhood blackout; the Gulf War(s) is an example of high-stakes energy-related conflicts on an international scale.
[Dr. Mathews is being escorted to a jail cell.] Police Officer: Here have a seat. [Dr. Mathews is now locked in a cell.] Dr. Mathew's: Today's lecture is about energy policy but also energy security. I am in the local jail. It's a tad spartan but it is an important aspect of how we deal with our economy. This is not a new subject, it's not something that was added since September eleventh. We have always been concerned about energy security. When you are in a military combat zone one of the first things you want to do is prevent the other team from moving around. So in doing that you take out their fuel supply. One of the first things we did when we started invading Iraq is to knock out their electricity. It's one of the common things you do. Our energy security is important for our national interests and it is important for our quality of life. These are some of the aspects we are going to deal with. And guys, can I get out of here now. Officer, sir, where are you going. No, over here...please. [Dr. Mathews looks around the cell.] Dr. Mathews: Mommy? [Video fades out]
Our energy supply and systems are intricately connected to our way of life and our national security, and this lesson delves into those connections and better comprehend the energy-related events and circumstances in an ever-changing regional, national, and international landscape.
You'll be successful in this lesson when you can do the following:
Question: If you were in Europe would you be concerned about access to Russian natural gas?
Click for answer.
Read the Energy Security Council explanation of why oil is so important [180] to the U.S. Take note of why access to oil is important and flex vehicles among fuel choices (ethanol, natural gas, electricity) to reduce this sensitivity (economic impacts). Not discussed is the improving of fuel economy (higher mpg). Also, note that imports of crude oil are often a cause of oil insecurity with sometimes drastic impacts (gasoline rationing). We now are the leading nation for crude oil production and have significantly reduced imports (more on this later) but are still linked to international oil trade and the growing oil demand internationally.
This link above seems to be having some issues. So please take a look at these two links:
Oil and Petroleum products explained (use of oil) Energy Information Agency [181] The takeawy message being the importance of oil to the United States (heavy oil use).
How oil prices impact the U.S. economy [182] (Investopedia) The takeawy message being the importance of oil to the United States economy
The Organization of Petroleum Exporting Countries (OPEC), has a simple charge, seen in the map below. For the geographically curious, mouse over any of the OPEC members to see an expanded view of the country. As you look through these, take special notice of the positions of borders and access to major bodies of water, as these often account for much of energy-related political intensity in these regions.
This oligopoly (a monopoly only has a single controlling entity, an oligopoly has cohorts acting together to form a controlling entity) controls production via quotas for each member country. The lower the production, the higher the price per barrel (providing there is enough demand). The higher the production, the lower the prices per barrel, but more barrels are sold. (Note that Qatar is leaving OPEC to focus on natural gas production).
OPEC is important for 2 very important reasons:
Country | 1992 (total 1039.3 thousand million barrels) | 2002 (total 1321.5 thousand million barrels) | 2012 (total 1668.9 thousand million barrels) |
---|---|---|---|
Middle East | 63.7 | 56.1 | 48.4 |
S. and Central America | 7.6 | 7.6 | 19.7 |
North America | 11.7 | 17.3 | 13.2 |
Europe and Eurasia | 7.5 | 8.3 | 8.4 |
Africa | 5.9 | 7.7 | 7.8 |
Asia Pacific | 3.6 | 3.1 | 2.5 |
If we look at the price per barrel over a long time period (normalized to adjust for inflation) it is very evident that price instability influences the industry. This has major impacts because oil is still the dominant energy source for the world, including the US.
After 2000 the price increased, dipped, and spiked at above $100 per barrel! This link shows missing data. [184]
Now take a look at what the flow of U.S energy sources looks like. This chart is represented in quadrillions of BTU's, which about covers a year's worth of energy for this country. Notice the breakdown of where our energy comes from, how it is used and consumed, and particularly how dominant oil is in the mix. Most of the oil goes into transportation, there is some contribution from biomass but in 2018 it was ~5%.
View a 7:45 video describing the Sankey Diagram [185] from 2015.
Dr. Mathews: This is a Sankey diagram that gives us an indication of where we're using energy in the United States and its various sources. And so if I point a couple of things out, we have electricity generation over here, and we also have various sectors-- the residential, the commercial, the industrial, and the transportation systems.
So here's what we call energy services. So this is the combination of all our transportation energy and energy that we utilize. One other thing to note is that we reject a great deal of energy. Obviously, when we are using steam as a means of generating electricity, we are having a great deal of rejected heat. So the energy coming into the turbine, we don't extract all of it because we throw away this hot water, this low-temperature steam as well, and that's where that rejected energy comes from.
Even in transportation services, our vehicles are inefficient. We generate a lot of heat, where really we'd rather have kinetic energy. And so there are limits on how much we can improve that if we're, indeed, being restricted to the thermo cycle, that steam, that high-temperature means of generating energy.
So the thickness of these lines from these various sources-- so petroleum, biomass-- gives you an indication that we use a great deal more petroleum than we do biomass in our energy systems, but we get a sense of where those various energy sources contribute towards. The units here are in quadrillion BTUs, and so this is a great deal of energy. But let's simplify it a little bit and see where the individual fuel sources contribute to.
So petroleum is definitely serving transportation. You can see that the bulk of it goes to our transportation services. Again, note the inefficiencies in the system because we generate a great deal of heat when we'd really like that kinetic energy to get us from A to B. Industrial users, obviously, some fuel oil as well goes into industrial uses. But the bulk of this transportation you can see is really coming from petroleum.
If we add in-- clicking the wrong button. If we add in biomass, you can see that biomass goes to industrial users. So a lot of that is going to be agricultural waste. People like the paper industry, they're going to cut down trees, use the rest of the biomass in their industrial heat needs to generate steam. But other uses as well. A lot of this is agricultural waste.
We do have a contribution to transportation services. The bulk of that is going to be in the form of ethanol in the United States, with a smaller contribution of biodiesel.
If we look at natural gas, we have a lot of industrial users. Again, they're using that for heat. Commercial users. Again, that's heat. Industrial users are going to use it for high-temperature steam as well for their particular needs. And of course, at home, natural gas for cooking, water heating, and home heating as well is now a significant source.
We are using a great deal more, however, going to electricity. The shale gas revolution has enabled natural gas prices to be considerably reduced and cheaper than coal. And so what we see is more utilities switching to utilize natural gas. When I do turn on coal, you can see it's actually a little bit larger.
This is 2015 data. I'm recording this in early 2017. I expect the new data to come out in another month or so, and we'll see a little bit of changing in the thickness. But for the most part, this would still be a good representation for a couple of years on. If we're now in 2020 and I haven't updated, please yell at me and I will certainly do so.
So moving on and adding in the coal, obviously, coal primarily serves electricity generation. Around 10% of the coal doesn't go into that area. Some of that's going to be coking coal, some of that's going to be direct uses for industrial, where they're looking at steam generation. A lot of it's coking coal, particularly for the steel industry.
Moving on to nuclear. You can see that, obviously, it serves electricity generation. And then if we start adding in the renewables, hydro is, of course, the largest. Mostly electricity generation. Some large industrial users will deliberately move close to hydroelectric sources and be very large consumers there and benefit from that large scale cheaper pricing. And of course, we don't want to move electricity over any considerable distance either, and so that makes that process a whole lot more efficient.
Wind, growing significantly. Still not as large as hydro but is certainly getting there. So while hydro is generally stagnant in its production, we're not going to see any significant increases in the big scheme of things, wind is still a growing contribution. Geothermal is next. That's been relatively steady. We don't have many locations where we generate electricity from geothermal. That, of course, may change, if CO2 has value and/or depending on how effective wind and other renewables can compete.
Moving next to solar. Solar I wouldn't have even mentioned a number of years ago. It's more than geothermal now. It is one of the most rapidly growing contributions to energy. Mostly, you can see here in the form of electricity, we have both solar plants serving the grid, as well as individual solar cells on roofs serving commercial and primary residential users.
So solar is one of the most rapidly growing entities. It started off very small so it can grow very rapidly, high percentages. We'll get to see what happens with policy and cost and subsidies, so the continuing contribution or the increasing contribution of renewables to our energy usage. Remember, we also have challenges with things like closing down nuclear plants. And we'll see whether natural gas prices still, indeed, stay relatively cheap or whether there are more users and then the price starts to go up again. And then I think we'll flip-flop a little bit back and have a little bit more coal and natural gas in the coming years for electricity derived percentages. Anyway, that is the flow of energy in the United States.
To understand the events leading to the Arab Oil Embargo of 1973 you need to understand why Israel is in its unique situation. Go to the CIA World Factbook and select "Israel" look at the "background." Just as we Brits managed to screw up completely every country we ever "owned," Israel is no exception. It is a United Nations created country. In 1973 Egypt and Syria jointly attacked Israel on Yom Kippur (the holiest day in the calendar). It was the age of the "Cold War". Syria was receiving military supplies from Russia and Israel military supplies from the US, UK, and the Netherlands. When Israel had survived the initial attack, recovered their lost ground, and looked to be capable of capturing large chunks of Egypt, the Arab nations (note this is not the OPEC nations) embargoed (refused to sell) crude oil to the US, UK, and the Netherlands. They later expanded the embargo to the rest of Europe. The "Arab nations" are many of the key OPEC members. The resulting loss of crude oil and considerable uncertainty in the markets resulted in something America was not used to: rationing of gasoline and very significant gasoline price increases. As a result, conservation, efficiencies, nuclear power, the strategic petroleum reserve, membership in the IEA, increase domestic crude production, and fuel diversity became important to America's security. Does this sound familiar? Consider these options when you listen to the current administration's Energy Plan!
The events of the 1973 Arab Oil Embargo resulted in the US joining the International Energy Agency [186] and the formulation of the Energy Policy and Conservation Act of 1975. There were 2 important outcomes from these events (the act and joining IEA):
Similarly, the Middle East also has much of the World supply of natural gas.
Region | Years |
---|---|
North America | about 10 |
South and Central America | about 45 |
Europe and Eurasia | about 60 |
Middle East | about 145 |
Africa | about 70 |
Asia Pacific | about 30 |
The events of the Gulf war and many other conflicts and embargoes have demonstrated the relative ease by which the flow of oil can be disrupted. The transportation of crude oil over large distances, geographic or political bottlenecks, and the concentration of the oil producing regions makes dependency on oil a dangerous situation. As pointed out already, pipelines are very easy targets. They are hard to protect because of their length and they are not easy to fix when there are problems (man-made or natural). There is a similar threat to energy security if we are dependent on natural gas (like Europe).
Oil resources, which are represented here in red, appear fairly well dispersed according to this map, although lots of oil is under the control of specific countries and regions. But wait.....the U.S. appears to have no oil resources. Why? Click on the link below the map to find out why the U.S. appears empty.
The Iran/Iraq war resulted in reductions of the production of crude oil because of the fighting and deliberate targeting of oil production regions and flooding (did I tell you about Iraq opening the floodgates of a large dam to flood an Iranian oil producing region?) Obviously the oil field fires of the Gulf War demonstrated the outcome of deliberate sabotage. Natural disasters such as earthquakes can also produce fires and disrupt the flow of oil and natural gas.
Looking at this image you should be able to easily identify the three significant bottlenecks in the routes used to transport oil from the Persian Gulf to Europe and points beyond. This illustrates the significance of geography to a region's political and economic well-being, and the geographic nature of conflicts, disputes, and alliances between regions and countries. This beautiful view of Northeast Africa and the Arabian Peninsula was captured by NASA's Galileo spacecraft, on December 9, 1992, as it left Earth en route to Jupiter. Visible are parts of Egypt (left of center), including the Nile Valley; the Red Sea (slightly above center); Israel; Jordan, and the Arabian Peninsula.
Imagine the disruption of oil transportation and world energy supplies, to name just one product, that would occur if the Suez Canal, Strait of Hormuz, or the southern Red Sea port near Yemen were closed, shut down, or locked up.
As usual "the times, they are a changin'!"
Please look over the current White House stance on Securing American Energy [188] (apologies for the use of political documents).
The general topics are:
You should have the goal of writing a short paragraph on each of these subjects above. Here are a few (5) pages extracted from the Blueprint for a Secure Energy Future [189]to get you started.
Also take a quick scan of the George Bush era stance [190].
This map represents a visual summary of the topics and ideas relating to Energy Security. It's a quick way to compare your notes, see the links, and get a quick refresher on the main concepts for this lesson. Move the mouse over the image for more information. When finished here take the lesson 8 quiz.
Accessible Version (word document) [191]
After looking at this map, please take the L08 quiz.
[Dr. Mathews drives onto camera by sliding his car on an unpaved parking lot. The tune from "The Dukes of Hazard" is playing the background.] [Dr. Mathews climbs out of his window as race car drivers do.] Dr. Mathews: You know I love "The Dukes of Hazard" as a kid growing up in England watching my three television channels. Fortunately part of the attraction is all the dust I've just generated. Unfortunately, these very small particles from these unpaved roads are going to stay in the atmosphere for quite a long time. They can cover quite large distances along with other emissions like sulfate aerosols, particulates coming out of my exhaust, and other fumes. [The camera zooms into the car's exhaust pipe and then back to Dr. Mathews.] They are going to cause problems. Part of these problems are regional haze and also lower air quality. This is what we are going to look at and how we can reduce them. One way is, don't drive like me. [Dr. Mathews struggles back into his car as the theme song begins to play again. The sound of a car peeling out plays as Dr. Mathews drives away.] [Video ends]
This lesson is about the consequences of all the moving about that we do in our vehicles. You will be working towards the following learning objectives in this lesson:
What we typically call smog is primarily made up of ground-level ozone (photochemical smog). While ozone in the stratosphere, high above the Earth protects human health and the environment, ground-level ozone is the main harmful ingredient in smog.
Ozone is a secondary pollutant - it is not released into the atmosphere directly, but is formed by other released pollutant interactions. The equation that is important is as follows:
NOx + unburned hydrocarbons or any volatile organic compounds (VOCs) → sunlight over the arrow O3
Watch the following video that talks about the science of smog. It is almost 6 minutes long.
On July 26, 1943, Los Angeles was blanketed by a thick gas that stung people's eyes and blocked out the Sun. Panicked residents believed their city had been attacked using chemical warfare. But the cloud wasn't an act of war. It was smog.
A portmanteau of smoke and fog, the word "smog" was coined at the beginning of the 20th century to describe the thick gray haze that covered cities such as London, Glasgow, and Edinburgh. This industrial smog was known to form when smoke from coal-burning home stoves and factories combined with moisture in the air. But the smog behind the LA panic was different. It was yellowish with a chemical odor. Since the city didn't burn much coal, its cause would remain a mystery until a chemist named Arie Haagen-Smit identified two culprits: volatile organic compounds, or VOCs, and nitrogen oxides.
VOCs are compounds that easily become vapors and may contain elements, such as carbon, oxygen, hydrogen, chlorine, and sulfur. Some are naturally produced by plants and animals, but others come from manmade sources, like solvents, paints, glues, and petroleum.
Meanwhile, the incomplete combustion of gas in motor vehicles releases nitrogen oxide. That's what gives this type of smog its yellowish color. VOCs and nitrogen oxide react with sunlight to produce secondary pollutants called PANs and tropospheric, or ground-level, ozone.
PANs and ozone cause eye irritation and damage lung tissue. Both are key ingredients in photochemical smog, which is what had been plaguing LA.
So why does smog affect some cities but not others? Both industrial and photochemical smog combine manmade pollution with local weather and geography. London's high humidity made it a prime location for industrial smog. Photochemical smog is strongest in urban areas with calm winds and dry, warm, sunny weather. The ultraviolet radiation from sunlight provides the energy necessary to breakdown molecules that contribute to smog formation. Cities surrounded by mountains, like LA, or lying in a basin, like Beijing, are also especially vulnerable to smog since there's nowhere for it to dissipate. That's also partially due to a phenomenon known as temperature inversion, where instead of warm air continuously rising upward, a pollution-filled layer of air remains trapped near the Earth's surface by a slightly warmer layer above.
Smog isn't just an aesthetic eyesore. Both forms of smog irritate the eyes, nose, and throat, exacerbate conditions like asthma and emphysema, and increase the risk of respiratory infections like bronchitis. Smog can be especially harmful to young children and older people and exposure in pregnant women has been linked to low birth weight and potential birth defects. Secondary pollutants found in photochemical smog can damage and weaken crops and decrease yield, making them more susceptible to insects. Yet for decades, smog was seen as the inevitable price of civilization. Londoners had become accustomed to the notorious pea soup fog swirling over their streets until 1952 when the Great Smog of London shut down all transportation in the city for days and caused more than 4,000 respiratory deaths.
As a result, the Clean Air Act of 1956 banned burning coal in certain areas of the city, leading to a massive reduction in smog. Similarly, regulations on vehicle emissions and gas content in the US reduced the volatile compounds in the air and smog levels along with them.
Smog remains a major problem around the world. Countries like China and Poland that depend on coal for energy experience high levels of industrial smog. Photochemical smog and airborne particles from vehicle emissions affect many rapidly developing cities, from Mexico City and Santiago to New Delhi and Tehran. Governments have tried many methods to tackle it, such as banning cars from driving for days at a time. As more than half of the world's population crowds into cities, considering a shift to mass transit and away from fossil fuels may allow us to breathe easier.
We also normally think of smog as something that occurs in cities, due to excessive traffic and emissions outputs.
Smog requires:
Ozone (O3) is the main component of photochemical smog. Particulates from combustion can also be present. The most dangerous smog is when both ozone and sulfate aerosols are present. The famous Killer Fog of London during the mid 1900s and the late 1800s was comprised of sulfate aerosols and smoke (particulates) from the coal fires used to heat homes and businesses. Over a 4-day period in 1952, the London Smog was probably responsible for about 3,000 or so "extra deaths" that year. The English expression would be "kick the bucket." And it would have been the old, ill, and infirm who died, not healthy Londoners. In New York City during the late 1800s, improving the air quality took the passing of a law that required anthracite coal (little smoke and low sulfur, so no sulfate aerosols) as the fuel of choice. This law, ultimately, was responsible for the rapid growth of anthracite mining in NE Pennsylvania at the turn of the century (1900's).
Smog is a problem because it is concentrated pollution. In the normal events of the average day, our pollutants are released to rise above our cities to be blown elsewhere (this upsets the Swedish when British pollution kills their forests (acid deposition related)). However, we can also have a temperature inversion. This is when a layer of warm air acts like a lid containing pollutants sitting over a layer of cold air. The situation is more common in valleys as the cold air can collect in the bottom of the valley (this is how fog forms, stagnant cold air sitting over river valleys).
At night, the ground level temperature cools faster than the air above it. Pollutants become trapped under the layer of warm air. As the sun rises in the morning, the ground level temperature warms up faster than the air above it, pushing the air upwards, which breaks up the warm air layer, allowing the pollutants to escape. However, if there is no wind, the air can become stagnant.
-Marconia County Web Site.
No matter what subject I am discussing, there are always students who think that the ozone hole is the reason for everything. Hint: It is not. Ozone holes are not something I would normally cover, but due to overwhelming interest in the subject (from your input), some explanation of the issue is in order here. But note it is not the major cause of climate change.
The sun emits all kinds of wavelengths that impinge on the outer surface of the planet (the atmosphere). Fortunately, the ozone that is high in the atmosphere screens much of the UV rays out. The ozone layer is in the stratosphere between 10 and 30 miles up.
When I was in Australia (one of the skin cancer leading nations) most of the kids on the beach were running around wearing full coverage bathing suits that look like a thin wetsuit. The material provided protection against the UV rays. In the center of town was the cancer treatment center. It is not uncommon for some of the older residents to go once a year to have the skin cancers removed. In the US skin cancer is more common on the left arm than on the right, why? It is due to how we drive and expose the left arm to more sun exposure.
The chemicals that we use to provide air conditioning, etc. are very stable, so stable that in the atmosphere they can rise to the outer layer of the stratosphere where the ozone resides. Once there the chlorine molecules can destroy 10,000 ozone molecules. The chemicals of concern come from commercial and industrial uses. The chemicals (refrigerants) are also used in heat-pumps and in refridgerators.
Source of Ozone | Percent |
---|---|
Solvent Cleaning Products | 36.1% |
Sterilization | 3.0% |
Refrigeration & Air Conditioning | 29.6% |
Foam Products | 14.3% |
Aerosols | 5.0% |
Other Products Including Halons | 12.0% |
The solution is relatively simple; STOP using ozone-destroying chemicals (Chlorofluorocarbons - CFC's, and others)! The Montreal Protocol became effective in 1989 with 160 countries eliminating or phasing out ozone-depleting chemicals. You can help by having your vehicle air conditioning fixed at locations where they do not release the chemicals into the atmosphere, and have your refrigerator refrigerant disposed of properly before the fridge goes into the landfill. As ozone is formed naturally, the ozone hole(s) will be repaired naturally. The problem is time - this is not going to occur until you are all much older (about 40 years). The process of formation is slow. Those ozone-destroying chemicals that were released in the 80's are still on their way to the ozone layer. So you and your family will need to use sunscreen and protect your skin and eyes against the UV-B rays in particular (to prevent cataracts). Unfortunately, penguins have no such protection. Take extra care if you are close to the equator (more exposure due to the Earth's angle towards the sun) and close to the poles (but don't worry about the Czechoslovakians!)
Watch the following 1:51 minute video about the destruction of the Ozone Holes.
Say goodbye to large ozone holes. A new study from NASA scientists suggests by the year 2040, the Antarctic ozone hole will be permanently smaller than the giant holes of today.
Since the early 90s, observed hole sizes have been larger than 12 million square miles with exact sizes changing each year. The ozone hole is a seasonal thinning of the ozone layer over Antarctica. The ozone hole size varies in part due to levels of ozone-depleting chemicals in the atmosphere. Man-made chemicals that destroy ozone are transported from the equator to the poles. In the Southern Hemisphere, they are trapped by the winds of the polar vortex, a ring of fast-moving air that circles the South Pole.
Although levels of these chemicals have been declining since the late 1990s due to the Montreal Protocol they will remain in the atmosphere for years, affecting ozone levels well into the century.
High in the atmosphere, the chemicals react with sheets of iridescent ice clouds which trigger the destruction of ozone. In years with warm temperatures, fewer ice clouds form, resulting in holes that are smaller. In years with cold temperatures, more ice clouds form, resulting in holes that are larger. But in order to understand how hole sizes will change in the future, scientists needed a more accurate picture of levels of man-made chemicals in the atmosphere.
Using NASA’s AURA satellite, scientists determined how chemical levels In the ozone hole, varied each year. With this new information, we can look into the future and say with confidence that ozone holes will be consistently smaller than 8 million square miles by 2040. And that will really be a milestone that we’re finally past the era of big ozone holes.
Smog is caused by the ozone hole! Nope! Ozone at ground level contains ozone that was created at ground level from a combination of pollutants in the summer months in polluted areas. Smog has nothing to do with the ozone hole(s).
Climate change is enhanced by the ozone holes as it lets in more energy. Nope! The energy wavelength of interest for climate change is IR not UV. Climate change and the hole are however related, the gases that deplete the ozone are also greenhouse gases, and climate change can affect the ozone layer.
There is no ozone over the pole. Nope! We are discussing a reduction in the concentration of ozone - not the complete removal - so a "hole" is a bit misleading.
It is only a problem in the Southern Pole. Hmmmmm. Okay, it is a problem in the South Pole, mostly because during certain times of the year the "hole" goes walkabout and loses the circular shape and can cross populated areas such as the coastline of Australia. The North Pole "hole" has further to travel before crossing highly populated Europe. UV-B does impact phytoplankton and so it is a problem in both poles as phytoplankton is vital for the food chain. No phytoplankton, no krill, no krill no krill-eating whales, etc.
Click on the image below to open the EPA report on Smog.
While this is an old report, the information has remained the same. Please read pages 1-3, and page 8 for more details about the health impacts of smog and how it can be avoided.
We have seen that areas with smog problems tend to be major cities as that is where there are lots of (dirty) vehicles. Smog is also an issue in areas close to major refineries such as the Texas basin where much of the refining capacity for that region is located (because of Texas oil and offshore oil from the Gulf of Mexico). So if there are 4 things needed to form smog, then we can reduce smog by reducing the precursors. There is not much we can do to block out the sun, or to reduce the outside temperature, so we are limited to reducing the precursor emissions of NOx and VOCs. In particular, we need to reduce or eliminate the anthropologic emissions of NOx and VOCs.
We have already discussed reducing the volatility of the gasoline fuel as one method of reducing the VOC emissions. This takes place in the blending stage of the refinery operation. By limiting the quantity of the more volatile compounds, the gasoline will evaporate less. This results in the refinery having larger quantities of light compounds to dispose of (in less profitable ways) which raises the cost of the gasoline just as do all the approaches where something needs to be changed. This reduced volatility fuel is a "summer blend." The lower temperatures of Fall, Spring, and Winter reduce the gasoline emissions, and thus reduce smog formation because smog requires warm (mostly summer) temperatures.
So the summer blend is only used in the summer and only in those locations with poor air quality (non-attainment area). You might ask how do gasoline vapors escape? When you "fill her up" the first thing you do is open the cap to the gasoline tank. What happens next on a summer day? Hsssss.... Gasoline vapors escape! And it is not only from the open "gas" tank, but also other locations: from the engine, the exhaust, fuel lines, and the gasoline tank. One approach is to capture these vapors from the tank with special nozzle attachments on the metal part of the gasoline hose. While it won't capture all of the volatile gasses escaping from the moment you unscrew the cap, it will capture the vapors that will be displaced by filling the tank up with gasoline. These vapors are cooled back into a liquid and sent back to the refinery.
This table provides a quick summary of the methods used to reduce NOx emissions in vehicles. For those of you keeping score at home, the information here combines NOx emissions issues from this lesson, earlier lessons, namely Transportation (L05), and issues in upcoming lessons: Climate Change (L11 & 12), and Acid Deposition (L10).
Method | Result |
---|---|
Oxygenated Fuels | The addition of MTBE (or ethanol) in the summer reduces NOx by lowering the temperature of the combustion process. |
Alternative Fuels | Methane (compressed natural gas), ethanol, etc. will have lower levels of NOx emissions. |
Catalytic Converter | The NOx is reduced to N2 in the catalytic converter. It does not eliminate emissions but it will drastically reduce the emissions. However, all our gasoline vehicles have them, so this is not a solution to our current problems as it is already in place. |
Improved Catalytic Converters | One of the reasons to reduce sulfur from gasoline to very low levels is because the S (as a catalyst poison) would reduce the effectiveness of the catalytic converter. The new lower S standards (<30 ppm S in gasoline) allow for better catalytic converter operation and also newer more effective catalysts. |
Hybrid Cars | Hybrid cars manage to reduce pollutant emissions via a combination of higher efficiencies and perhaps by utilizing the electric engine in those already polluted areas such as the centers. In Europe, one proposal would require that gasoline-fueled vehicles be banned from the inner city parking areas thus encouraging the use of cleaner cars. Thus, a hybrid might function as a gasoline engine for the commute to work but as an electric engine when within the city. |
Emission Free Vehicles | Electric or fuel cell cars have no NOx emissions from the vehicle itself. Encouraging their use (fleet vehicles, tax credits, parking availability-fuel cell car only, and other approaches such as allowing these cars in high occupancy vehicle lanes with 1 driver and no passengers) would aid electric vehicle adoption. |
Getting Old Cars Off the Road | A few vehicles are the cause of much of the pollution. If we have a buy-back of your old Junker program (then squish the car and recycle it) we can remove them from the road. Emission checking (emission inspection along with the traditional vehicle inspection) is also a key component of ensuring the pollution control equipment within the car is functioning but also for failing super and high polluting vehicles. Emission Inspections are often required in vehicles in non-attainment areas. |
Efficiency and Conservation AGAIN! | Always a right answer! All the methods of increasing vehicle efficiencies, such as increases in MPG and passenger occupancy, and the uses and development of more efficient methods of public transportation, are again applicable here and are all discussed in detail in Lesson 5 for those of you who would benefit from a review. |
Nitrogen is 78% of the volume of air. Normally, nitrogen atoms float around joined to each other like chemical couples. But when air is heated - in a high-temperature boiler's flame, for example - these nitrogen atoms break apart and join with oxygen. This forms "nitrogen oxides" - or, as it is sometimes called, "NOx" (rhymes with "socks"). NOx can also be formed from the atoms of nitrogen that are trapped inside coal (fuel NOx).
Part of the Clean Air Act is a reduction in NOx emissions from power plants using Low NOx burners. Three others are worth mentioning here:
Many of the approaches for NOx reduction are similar to those we discussed in the previous and upcoming lessons (Acid Deposition), so for the details on these techniques, I'd suggest you keep this in mind when we research those materials.
When I was a young boy the family moved to the plains of Cheshire, a region in the northwest of England that is very flat. From my bedroom window, I could see a couple of castles (I would have to lean out of the window precariously). When I go back home, my memories of the great view are rarely repeated because the view is now often hazy. The NW of England is an industrial area: Manchester, Liverpool, etc. My bedroom window view is also of Stanlow, one of the largest European refineries (Shell).
Tankers offload oil in the Mersey estuary and it is piped to the refinery. All the industry, the utilities, and transportation (lots of cars in a small place) contribute to the pollution. It is nothing like the peace and tranquility of State College. The cause of the haze is very small particles that can stay suspended in the air for days, and can thus travel large distances on the wind. There are a number of different types of particles depending on where you are, and the local events. Haze can be a natural event when the air is humid and contains many tiny suspended water particles (think Florida on a hot and humid day - recall this is one of the reasons that solar cells are not as efficient in Florida).
Visibility often is measured as the farthest distance from which a person can see a landscape feature. Haze currently reduces natural visibility from 90 miles to between 14 and 24 miles in the eastern United States, and from 140 miles to between 33 and 90 miles in the western United States. Visibility generally is worse in the eastern United States due to higher average humidity levels and higher levels of particulate matter from manmade and natural sources.
- EPA
Some of the natural particular matter (PM) emissions are from forest fires. The smoke contains fine ash particles and fine soot particles (if you have ever owned a fireplace, you know that the routine of having a chimney sweep removes soot periodically!) All combustion can produce small particles, and it is the small particles that contribute to visibility reductions and health-related problems.
Volcanic eruptions are also natural sources of particulates in the atmosphere. In addition to their potentially catastrophic consequences on the immediate localities and regions, they can also send particles high (many miles) into the atmosphere, and the fine particles can be very dangerous to aircraft (particularly those with jets), often forcing airline travel delays and the creation of alternative routes around the volcanic activity.
Dust from unpaved roads, the use of leaf blowers (often gasoline-powered, which means that VOCs are also released, contributing to more smog), and mowing the lawn, etc., all can add particles into the air and increase the smog problem, so those activities are best avoided on days where air quality is already low. Would people rather make sure the yard looks good, or do their part to preserve higher air quality?
The Clean Air Act classifies the size of these fine particles by two terms:
Dust is anything below 100 microns, and so we are focused on very small particles. The old standard was a limitation of the number of PM10 particulates in the air. Now, that law remains and there is another standard focusing on the very smallest particles below 2.5 microns. This is because the health impact of these smallest particles is greater than the slightly larger particles. Small particles enter into the lungs and can stay there (recall the discussion of Black Lung). Particles smaller than 1 micron not only enter the lungs but can also enter the bloodstream. This is a great concern because the small particles have a very large surface area (recall this is why we pulverize coal). Heavy metals and carcinogens from the combustion process coat these small particles. In the blood these chemicals and metals cause disease. Similar to the smog influences, these particles impact those who already suffer from limited lung capacity the most. So if you smoke, this is what you are adding to your lungs.
The cigarette is an example of biomass combustion. It produces much of the same carcinogens as does any combustion. In fact, the only way of producing these very small particles of < 1 micron is via the combustion process
The Environmental Protection Agency (EPA) classifies environmental tobacco smoke (ETS) as a class A carcinogen, the most hazardous classification for cancer causing agents. ETS kills as many as 53,000 nonsmokers in the United States annually; 3,000 from cancer deaths and 50,000 from cardiovascular disease and other tobacco-related illnesses.
- Smoking Cessation Program
Take a good look at the chart below. You'll see that, when the air is unhealthy, you are better off staying indoors and avoiding strenuous exercise (if only I could use this excuse more often to watch football and drink beer while eating chicken wings!)
Index Values | Levels of Health Concerns | PM 2.5 Cautionary Statements* |
PM10 Cautionary Statements* |
---|---|---|---|
0-50 | Good | None | None |
51-100** | Moderate | None | None |
101-150 | Unhealthy for Sensitive Groups | People with respiratory or heart disease, the elderly, and children should limit prolonged exertion. | People with respiratory diseases such as asthma should limit outdoor exertion. |
151-200 | Unhealthy | People with respiratory or heart disease, the elderly, and children should avoid prolonged exertion; everyone else should limit prolonged exertion. | People with respiratory diseases such as asthma should avoid outdoor exertion; everyone else should limit prolonged exertion. |
201-300 | Very Unhealthy | People with respiratory or heart disease, the elderly, and children should avoid any outdoor activity; everyone else should avoid prolonged exertion. | People with respiratory diseases such as asthma should avoid any outdoor activity; everyone else, especially the elderly and children, should limit outdoor exertion. |
301-500 | Hazardous | Everyone should avoid any outdoor exertion; people with respiratory or heart disease, the elderly, and children should remain indoors. | Everyone should avoid any outdoor exertion; people with respiratory diseases such as asthma should remain indoors. |
* PM has two sets of cautionary statements which correspond to the two sizes of PM that are measured:
As you can see we are getting better air quality (but this is still problematic for those at-risk groups).
The emissions from this smokestack are atrocious! Fortunately, we don't see this often in this country. Now, in other countries, that's a different story. Before there was regulation on particulate emissions this is what the stack of a coal power plant would look like. Even when the stack emissions are not dark we are getting pollution in the form of small particles that we need to clean before they reach the atmosphere. Not only is it a health issue, but it is also a waste of coal. Home fireplaces might produce black smoke because of the inefficient method of combustion but many modern fireplaces might have a catalyst to reduce particulate emissions.
What we need is a method of filtering, or pulling the particles out of the hot flue gas before they reach the stack. For coal-fired utilities, there are 3 approaches: a) Electrostatic Precipitators, b) Baghouses for pulverized coal combustion; for a Fluidized bed, c) a cyclone is commonly used.
Watch the following 3:56 minute video about Particulate Matter.
Dr. Mathews: So when we discuss particulate matter, we are talking about small particles that are smaller than 10 microns, and there's a sub-classification there of small particles smaller than 2.5. So PM 2.5. These very small particles have a number of contributions to environmental challenges.
And so anything that is on the smaller side, less than these 10 microns, can certainly go into the lungs. They can go into the bloodstream. Certainly, the smaller particles have very large surface areas. This is where carcinogenic material can go on as well. And that's why it's the smaller, smaller than 2 and 1/2 microns that are particularly troublesome for environmental issues, for human health, particularly.
Some of these small particles are going to be aerosols. They contribute to climate change. Actually, in a good way. They reflect more of the energy back, sunlight back, and so actually cause the planets. When we have volcanic emissions, you can sometimes see a cooling event on a couple-year period of time, if not longer in some cases, due to all that fine ash being up in the atmosphere.
And so we need to be able to handle these particulates and prevent them to go into the atmosphere. And we can do that by a couple of approaches. So if we'd like to remove them from a gas stream, we can do it through a cyclone. And so with a cyclone, the material comes in and gets rotated. And through that very, very high centrifugal forces, the particles get thrown out to the sides and can be extracted, whereas the clean air comes out.
In some cases, we will have these particles flowing through filters. And so, again, maybe some will go through. Some will stopped and get absorbed. And so your vacuum cleaner, for example-- we can have some filters that will prevent these going through.
We also have examples where we use electrostatic precipitators, for example. And so what we're going to do there is put an electric charge. That electric charge is going to give the particle a charged surface. And if I have a positive plate, then it'll get attracted to the plate, and we can remove the particulates that way.
And so PM 10, PM 2.5 Again, variety of approaches to clean these emissions, depending on what the size is and what the material is. They contribute, certainly, to regional haze. Obviously, some things like sulfur and aerosols make things like smoke worse. And of course, we've got other issues with very small particles going and affecting human health. And so that's PM 10, PM 2.5.
And just to give you an idea of how small that is, a human hair would be ~80 microns. And so we're talking about very small particles that we can't see very well. And because they're small, they can have a long time in the atmosphere. They're not going to fall and be brought down to the ground very easily. They can be blown around.
This Baghouse used to be at University Park, it gives you some idea of the scale of these systems. It is about a 6 story building, the flue gas passing through before exiting out of the flue. Within the building, there were 1000's of very large bags much like a vacuum cleaner bag (that can stand >110 °C). This building (and the stack) were demolished when we moved away from coal to natural gas for the steam plant. An Office of Physical Plant (OPP) building sits there now.
We have discussed fluidized beds already in the course (Lesson 02). The one shown below has both a baghouse (labeled as a fabric filter) and a cyclone system to return particles back to the fluidized bed if large enough, or if small enough they go through the baghouse (fabric filter) before the other products of combustion exit the stack. The cyclone uses centrifugal forces to separate particles from a fluid.
Watch the following 1 minute video: Baghouse Basics
There are many different sizes and designs, but baghouses all operate in the same basic way. One. The dust-laden or particle laden air or gas stream enters the bag house, travels along the surfaces of multiple fabric tubes and then passes outward or inward through the fabric. Two. The larger particles fall down into a hopper while the smaller particles accumulate on the fabric surfaces. Three. A cleaning mechanism occasionally removes the particles from the fabric tubes and they fall down into the hopper from which they are discharged. Four. the clean air or gas stream exits from the top of the baghouse.
Here is my effort at showing the particle trajectory. The separation due to centrifugal forces occurs because of the mass difference (size and density differences) between air and the particles (char, ash). The smallest particles have the least amount of centrifugal forces and thus are the hardest to separate (larger particles are much easier) to separate from the air. Obviously, there is a cost to adding these components (power-plants are large-scale operations) to reduce the emissions.
You can see a much better particle pathway in this video. Watch this 1 minute of the following cyclone animation. You can skip the first 30 seconds of company blurb.
Hurricanes are customized cyclones to serve different needs and which results from optimization functions such as maximize efficiency, minimize cost, or minimize size. Combining stochastic numerical optimization by changing the eight independent cycling dimensions. With a knowledge of particle agglomeration ACS is able to design the perfect geometry for each case. The colored dots indicate the particulates to be collected and the blue arrow represents the flow of gas that leaves the equipment.
For dusts with tendency to agglomerate such as biomass or coal fly ash among others. Efficiency is maximized thanks to the clustering effects of particles. In fact, the cyclone doesn't see as many small particles but clustered particles with bigger dimensions and thus easier to collect. Agglomeration increases with wide particle size distributions beyond residence times in the cyclone and large inlet particle concentrations. Agglomeration is maximized with the new developed hurricane MK cyclones. Emissions can be under 15% of those of other cyclones being as low as 30 milligrams a normal cubic metre for many industrial processes.
The schematic below shows a boiler with Electrostatic Precipitators that capture the fly ash (ash leaving with the flue) and the small particulates. Also shown is a low-NOx burner to reduce NOx emissions (less smog and what else???)
ExplainThatStuff! has a great article, Electrostatic smoke precipitators [203]. Pay particular attention to the section on how it works.
This map represents a visual summary of the topics and ideas relating to smog and problems with air quality. It is interactive so move your mouse over the text below for more details.
Accessible Version (word document) [204]
After looking at this map, please take the L09 quiz.
[Dr. Mathews is standing next to the famous Penn State Nittany Lion Shrine.] Dr. Mathews: Most of you all know that I am standing by the Nittany Lion Shrine. A beautiful artistic rendering of a puma or a mountain lion. It has been standing here since 1942. And every home game it has its own honor guard to protect it from visiting fans from desecrating it with other colors or symbols or even paint. But how would you feel if it had been under attack every single day? Ever since 1942, it’s been made under attack from acid rain or acid deposition. We're in the center of the northeast and we have some of the highest PH rainwater in the United States. This is made out of limestone and it is a single 32-ton block that has been beautifully rendered into this rather wonderful lion. But when it rains and this acid-y content it's going to start eating away at this limestone block. There is also acidic snow, there is also dry deposition, and there is acid fog. All of this is attacking this statue. But since 1990 and the clean air act of 1992 we have tried to reduce our sulfur dioxide emissions and reduce or NOx emissions. How we did that and the impact that it has had on our air quality and on our PH of the water is what we are looking at today. [Video ends]
This lesson will be successful if, when you're through with it, you're able to do the following:
Watch this 2 minute overview of Acid Rain.
What is acid rain? Acid rain is any form of precipitation with high levels of nitric and sulfuric acids. It can occur in the form of snow, fog, and even dry materials that settle to earth. Most acid rain is caused by human activities.
When people burn fossil fuels, sulfur dioxide and nitrogen oxides are released into the atmosphere. These gases react with water, oxygen, and other substances to form sulfuric and nitric acid. Winds may spread these acidic solutions over hundreds of miles.
After it falls to earth, acid rain enters water systems as runoff and sinks into the ground. This can make water toxic to prey fish, clams, fish, and other aquatic animals. The rest of the food chain, including non-aquatic species such as birds, is often affected as well. Acid rain also harms forests by damaging trees' leaves, robbing the soil of essential nutrients, and making it hard for trees to take up water. By designing cleaner power plants and using fewer fossil fuels, we can reduce the number of pollutants that create acid rain
The media is keen on using simplistic terminology to explain environmental issues, acid rain is one of those terms. What is it that the media has got wrong here? Glad you asked! The simple answer is that "acid rain" is not just rain. It can come in all forms of precipitation that you might encounter — snow, hail, fog, etc. But once again, this doesn't cover all the bases. The meteorology chaps use the term precipitation to indicate water falling to earth in any of its many forms (there is a big difference between 2 inches precipitation as water and 2 inches precipitation as snow). But here is the crux - not all precipitation is wet - sulfate aerosols are precipitation and they are dry.
So, now you know that people who use the term acid precipitation make me much happier than those who use the term acid rain. And students like you, who understand that acid deposition is a combination of all the components below, make me happiest of all (Now all I need to do is get you all jobs in the media).
Components of Acid Deposition
Blame is something that we like to assign, especially as it can be passed away from our own consumption patterns, but remember the pollution is generated as a by-product when electricity or fossil fuels are used. We could blame the utilities (but not nuclear or renewable utilities) but they did generate electricity cheaply. Back in 2000, 19 of the 20 cheapest electricity generation utilities were coal-fired. We like cheap electricity. We complain when the prices go up. But we also require clean air and water — but we don't want to pay for it. It is similar to gasoline. Additional removal of the S costs money, it is a cost that is passed on to you, the consumer. The cost is around 7 cents a gallon to meet the latest Clean Air Act amendments-API estimates. Less pollution typically cost additional investment and change that come at a cost ($).
The presence of SO2 and NOX in the atmosphere is what makes the deposition (rain) acidic.
SO2 + 1/2 O2→SO3
SO3 + H2O → H2SO4
NOx + H2O → HNO3
These acids, when dissolved in water, exist in the ionic state so that the hydrogen ions are free to wander around: 2H+ and SO4 2–. The pH scale is essentially a measure of the ions in the solution.
As shown in the charts below, the culprits for the emission of these gasses were vehicles for NOx, and utilities (mostly coal-fired) for SO2.
As you can see in the chart below, emissions of SO2 have been decreasing as we use less coal (changes in our electricity sources), are using cleaner coal, and through the use of SO2 scrubbers on coal-fired utilities. Some of these changes are due to emission reductions in the Clean Air Act. The largest reduction is due to the adoption of natural gas (and renewables). The natural gas switch was due to changing economics rather than policy.
There are natural sources as well as anthropologic. Here is some more volcano information concerning gasses [205].
Click on the link to listen to this audio file about Natural sources of acid precipitation [207].
Dr. Mathews: One whole day I had as a young man, we went to the Canary Island, which is a Spanish speaking set of islands off the North African coast; beautiful volcanic islands. And I remember two things very vividly. One was going up Mount Haidi. It was an incredible drive. I was amazed how religious these people were; there were crosses everywhere. And upon getting to the top there was a weather observatory and an astronomical observatory because the air was nice and clean there. And also there was sulfur lying around. There were little holes everywhere where you could actually pick up chunks of sulfur if you wished to. It smelt of rotten eggs, the volcano was dormant but giving off lots of gasses. The other thing that I remember vividly is on the way down the crosses were not there. The crosses were not there just for religious reasons, they were there when someone had gone over the edge. And with a thousand foot drop I was terrified the whole way back done. Anyway, volcanoes give off lots of gasses.
Much of Europe has been impacted by acid deposition, the famous Black forest has been severely hit and many lakes in Sweden no longer hold any fish. Europe is also a special case as this is where the industrial revolution started (also lots of high S-coal) and so it should be no surprise that the impacts have been felt there. The international aspect of pollution is also a major issue. Pollutants from the UK (SO2 & NOx) drift on the winds and pollute Sweden. Thus, even if you clean up your own backyard you are not tackling the issue of your neighbor's trash blowing into yours.
Here in the US, it is the Northeast that is suffering the most from the impact of acid deposition. Why?
So how do we measure the acidity of the rain? We use a pH meter and the pH scale to determine how acidic (or its opposite - alkaline) the water is.
Do you think you could put these relatively common household chemicals and bodily fluids into the correct order?
Looking at this pH scale, can you tell what pH actually is?
Pregnancy tests are based primarily on pH readings (peeing on a stick)- a woman's urine changes pH when she is pregnant. This is actually old technology that has been rediscovered (modern tests now detect hormones.)
So what is the pH of pure rain?
Rain is naturally slightly acidic as it can absorb CO2 from the atmosphere which alters the ionic chemistry of the water. Thus, to be acidic, the rain (or snow, or............) must be below (more acidic) 5.3 on the pH scale.
As the rivers become more acidic, the problems with acidification of waterways are:
As the acidity becomes significant, the life that the river can support is reduced to the more resilient fish.
Recall that not only can rain be acidic, but hail and snow too. When spring arrives the snow melts. If the snow was acidic, then there can be an acid event that can kill many of the fish in the stream. This tends to happen in streams because of the dilution factor in some of the rivers. The technical term is an episodic shock (or acid shock).
There are all sorts of metals and minerals in the rocks and soil that are dissolved by the acidic water and washed into the streams. Aluminum (Al) is of major concern as it can interfere with the breeding cycle.
There is also mercury (Hg) that is dissolved by the acidic water, washed into the streams, into the fish food, and into the fish. The issue is not that the mercury impacts fish, they don't care, but we should if we eat the fish. Mercury concentrates in the liver! Bears, Eagles, and other animals that eat the contaminated fish are also at risk. See the U.S. EPA Website on Mercury [208] for more information if you are interested.
The impact on trees is dependent on the acidification, type of tree, and interaction with the tree. The acid deposition can attack the leaves; sulfate aerosols lie on the leaves like a layer of dust (ever dust your houseplants?). Regional haze reduces the amount of light reaching the trees. Nutrients can be washed out of the soil. An acid fog can be in contact with the trees for long periods of time. Aluminum uptake is also a problem for the trees! Certain trees are more susceptible, however, and it is not uncommon to see what appears to be a healthy forest only to find an obviously distressed forest higher up (when the tree type changes).
Coming from the UK, I have seen a great deal of acid deposition damage. We used a great deal of limestone in our building and for decorative structural features, including statues (marble is by far a more expensive medium but is slightly more resilient). Limestone is common in PA and in large areas of the UK. Chemically it is CaCO3, calcium carbonate. It easily dissolves in slightly acidic water (stalactites and stalagmites are lime [stalactites are the ones that grow down, think tights go down!]). If you are interested, visit the Great Basin National Park website for some beautiful images of stalagmites [209].
When limestone is dissolved it forms calcium oxide (CaO) which is lime. (This is like the part in the movie that seems to be extraneous information but is important later on in the movie). One way to treat acid streams is with lime.
Unfortunately, many statues, countless gravestones, and the information they contained have been lost due to acid rain exposure. The acid deposition has "eaten away" the limestone. We now use special paint on our automobiles to protect the paint from acid damage. It costs about $13 more per car, but think of how many cars there are! How much is the loss of a statue? How much is the loss of a healthy stream in PA?
Acid does not all come from the sky! Pennsylvania has about 3,000 miles of polluted streams, creeks (I am not sure what the difference between creeks and streams are, we don't have "creeks" in the UK!). The culprit is not thousands of miles away, it is much closer to home: abandoned coal mines & culm piles. Recall when we discussed coal mining activities that the pyrite in the coal is uncovered and dissolves in the water, migrating through the abandoned coal mine. When the mines are abandoned, the pumps are taken out and the mines often flood with acidic water that can flow into the streams and pollute the water table. The Culm piles also expose the pyrite to the elements (wind, rain, hail, snow, etc.) and so they too contribute to the acidification of the local waterways. Pyrite is fools' gold and contains iron and sulfur.
[Video opens panning down a discolored stream.] Dr. Mathews: This is a beautiful area of the anthracite region. This is one of the many sulfur creeks. It gets that name from its yellow or orange color in nature. This is due to acid mine drainage. What happens is the iron discolors the bed, the stream bed, with this yellow coloration, it is called yellow boy, and it is actually iron hydroxide. Unfortunately, it means that the stream is in very poor health and it is not a good spot to go fishing. It is very sad to see the beautiful areas of this anthracite region devastated in this manner. [Video ends panning the stream.]
To the left, an old anthracite breaker stands in front of a culm pile. Recall that this culm can be cleaned and used to fuel fluidized bed combustors. The breaker is where the coal was crushed and sized. The coal which was rejected (because the particle size was too small or the coal obviously contained significant quantities of other rocks) was thrown away on top of the pile. The exposed pyrite in the pile will produce acid mine runoff when it rains.
The effects of AMD on wildlife can be significant, as evidenced by the map below. Look at the distribution of fish on this map, then click on the arrow to see where the major coal deposits are in Pennsylvania. See any connection?
Remember the difference between acid deposition and acid precipitation?
The sulfate aerosols (suspended fine solid particles of sulfate or tiny droplets of a solution of a sulfate or of sulfuric acid) that are also released into the atmosphere, are in many ways more damaging than the rain and hail. Their small size permits them to enter into our lungs where they cause breathing difficulties. The small particles also scatter light, which reduces visibility. After a good rainstorm, the visibility will often improve as the sulfate aerosols (and small particles) have been washed out of the air. In the US National Parks, 60% of the visibility reduction is attributed to sulfate aerosols. Dust from unpaved roads and small particles from forest fires (recall the PM2.5 challenges) also contribute. This has been so bad in the past that wildfires in Mexico caused unhealthy air in Houston (not a city renowned for healthy air in the first place). Thus, regional haze is a greater hazard when sulfate aerosols are present.
Recall that we looked at the regional haze challenges in the previous lesson.
NOTE This coverage map, unlike all the others you've encountered, simply illustrates the issues involved in Acid Deposition. There are not any active mouseovers on this one, but it remains a visual quick-reference summary of what I consider important from this first half of the lesson.
The Clean Air Act was very successful legislation for improving air quality (with an initial focus on acid "rain"). The three images below show significant reductions that occurred between 1980 and 1999 concerning the SO2 and NOX concentrations. These reductions have continued into the 2020's and will continue to improve with renewable energy and vehicle electrification (see the chart below the maps).
These reductions have continued! The reduction is even more impressive when you factor in population growth, increase in the gross domestic product, and the increases in miles driven and energy used. Here the 6 common pollutants are CO, lead, NOx, VOC's, PM10 / PM2.5, and SO2.
Acid deposition problems prompted the “Acid Rain Program” within the Clean Air Act of 1990. This, along with the Amendments of 1992 and some later amendments, tackled the point sources of SO2 and NOX. Mostly the larger coal-fired utilities were impacted (about 110) and started to reduce emissions in 1995, and further reduced emissions in 2000. Obviously, from the figures above, we have had great success in reducing the emissions of these gases. So how was this achieved?
Limits were placed on how much these large, mostly coal-fired utilities, could emit. Simple, right? Well, perhaps not as simple as you might expect. If all the utilities had to reduce emissions by the same percentage we would lower the emissions but at drastically different costs. So what? Well, this had been the approach used in other countries and the approach used in the past, but there is a better way: Emissions Trading!
This was the centerpiece of the acid rain program and now the preferred approach for some emission reductions. Limiting the total number of permits controls the quantities of emissions permitted. By requiring that a utility provide a permit for every ton of SO2 (the program started with SO2 so let's look at that scenario) they emit. If a permit is not available they have to clean up those excess emissions. Okay, so far this is not any different from mandated reductions. Here is the key; you can buy or sell permits at market value. The market controls the cost of permits. Overall this is a lower cost reduction strategy since a utility company can calculate if it will be cheaper to purchase permits, clean up the emission to the minimum (depending on how many permits they have), or reduce emissions to below the number of permits and sell off the excess permits to lower the cost of meeting the reduction. This lowers the cost of meeting the emission reduction, and so hopefully the cost associated with meeting the reductions will not impact the price of electricity as much (lower increases in the cost of electricity for you and me)! Given that most companies own at least several utilities much of the “trading” can occur in-house.
There are several methods:
The EPA provides a nice site explaining the Air Markets Program [211]. Give it a quick look over. - It is a good reiteration of the acid rain story (helpful for good exam scores).
This market-based approach worked well and was a major US success when it was included in the Kyoto Protocol (more on that in the next lesson). The NOX emissions were more complex as it depends on boiler type and size. The next few pages look at how the emissions were reduced either by preventing their formation or by cleaning up the flue gas prior to it going out of the stack.
A summary of the Clean Air Act aimed at creating a healthy, productive environment, linked to sustainable economic growth and sound energy policy:
A more modern examination of the Acid Rain Program results [212] can be found on the EPA website.
Coal quality is very variable, which is one reason that we take the measurements of proximate, ultimate analysis along with calorific value. Shown in the graph below is the acceptable line for emissions of 1.2 pounds of sulfur dioxide per million BTU of chemical input. If you purchase a coal below the green line and you have an efficient utility (normal efficiency should be >35%) then you will not have to spend money on cleaning the coal or installing a scrubber. As in the case of our crude oil, the quality of our coal is decreasing because we have consumed much of the cleaner coals. Many of our coal regions are not under the green line and so a sulfur reduction strategy is necessary to ensure compliance with the Clean Air Act. One of the easiest methods of reducing the sulfur dioxide emissions is to buy the cleaner (and thus more expensive) coal from another coal seam.
Unlike most coal properties, the S content (from the ultimate analysis) has very little to do with rank. Anthracite does have a low S content because the high temperatures necessary for anthracite creation would have been sufficient to remove the S as H2S. However, increasing in rank has very little to do with S content, rather you need to go back millions of years and look to see where the sea shore was. Seawater infiltration into the existing coal seam was responsible for much of the enhanced S content of some coals. Fortunately for the Western states, their coal was not exposed and they tend to have the cleaner (lower S) coals. So as Wyoming coal has a lower S content there was a massive switch to this cleaner coal.
Coal use is declining in the U.S. as we use more natural gas for electricity generation and industries also move towards natural gas. A smaller contribution comes from more wind power generation.
The formula for this process looks like this: SO2 + CaCO3 + 1/2O2 + 2H2O → CaSO4 + 2H2O + CO2
The schematic above is of a device known as a scrubber. Their role is to take the flue gas with the products of combustion and remove the SO2 emissions prior to the flue gas being released out of the stack. This wet device also has the advantage of reducing some of the particulate matter. There is a dry version as well, but the wet scrubber is my favorite!
Most of you are, quite literally, surrounded by a version of this solid byproduct much of the time - GYPSUM is the primary material in the drywall, or wallboard, that makes up the interior walls of most new houses, apartments, and buildings today. If you're sitting in a place right now that has a smooth or textured painted surface or has wallpaper, then it's a pretty safe bet that gypsum lies underneath.
We have discussed approaches to reducing NOx from automobiles. One approach used was the use of a catalytic converter. The same technology can be used to remove NOx from power plants. The catalyst works in exactly the same way but on a much larger scale. The buildings can be 8 stories high and are the size of an apartment complex. A building that size will hold millions of dollars worth of catalyst that has to be replaced every few years. So, NOx reduction is an expensive process.
Don’t worry too much about the complexities of low NOx burners. It is enough that you know that they work by controlling the mixing of the air (oxygen) and fuel, and lowering the temperature of the flame (by controlling the mixing). You need to produce a radical-rich zone so that you can attack the formed NOx. This has to happen early in the flame or else the nitrogen in the char will most likely form NOx. Hopefully, the result will be more ubiquitous nitrogen and we will release less NOx into the atmosphere.
There is a method of burning coal that uses existing technology to produce electricity with very low emissions of both NOx and SO2: Fluidized Bed Combustion. The fuel need not be coal - fuel flexibility, in fact, is one of the reasons that this is an attractive boiler configuration, but most PA fluidized beds tend to be in the anthracite region, where there is abundant and FREE fuel: Culm Piles (or so called "gob piles" in Western PA).
These "manmade mountains" of reject coal actually contain a significant quantity of coal (recall these culm piles help produce acid mine runoff - from the pyrite contained in the anthracite). By removing the culm pile, producing electricity, employment, and taxation and cleaning open-pit operations (more on that in a bit) these operations significantly improve the local area, environmentally and economically.
The reject coal is cleaned then combusted. The relatively large pieces of coal burn in the presence of limestone. Suspending the particles with air flowing from underneath enables the coal to be combusted slowly, the ash forms most of the bed (where the suspended material is is called the "bed") along with some coal and lime (from the limestone CaCO3 heat-----‡ CaO (Lime) + CO2). This gives the coal a long residence time in the bed, allowing lower temperature combustion (thus less NOx) and the S is not emitted into the atmosphere because it is captured in-situ (in place) by the limestone. CaO + SO2 + 1/2 O2-‡ CaSO4 (gypsum)
Like the output from S scrubbers explained above, the gypsum becomes a solid and can be used to fill in the old strip mining holes to restore the damage from old abandoned mines. But, the output from this process produces a less pure form of gypsum than from scrubbers, so this gypsum is not usable for wallboard materials (it is just a coating over the lime particle).
You've heard me say this before, and I'll say it again, because if you leave this course in a few weeks remembering only one thing (which I hope is a massive under-estimate), then it is this; When discussing possible solutions for pollution from fossil fuels, Efficiencies & Conservation are the 2 answers that are nearly always right. We have spent much time throughout this course talking about these two issues, so below are simple summaries of the main efficiency and conservation points as a reminder and refresher.
This is not going to do much for SO2 emissions from gasoline engines (as the S content in gasoline is already so low, and getting lower (30 ppm)) but will lower emissions from diesel engines (low sulfur diesel achieves this too). However, increased efficiency in automobiles (mpg and passenger occupancy) will reduce NOx emissions. We talked about this in detail in the previous lesson on SMOG. Hybrid cars, electric cars, fuel cell cars and most alternative fuels will also reduce emissions either directly or through increased efficiency. There are also public transportation options.
More efficient electrical devices in the home mean less electricity demand. Less electricity demand means less pollution.
There are plenty of non-fossil fuel utility options (renewable & nuclear). Biomass does not contain much S and so its utilization would help SO2 emissions. Natural gas combustion is a more efficient method of electricity production than existing coal utilities. While there are practically no S emissions there will be NOx emissions but at lower levels than old coal utilities (via a combination of increased efficiency and no fuel-NOx). If we use gasification we can clean the S and N from the gaseous fuel and obtain higher efficiencies in the generation of electricity (clean transportation fuels too).
You can, of course, pick from certain options how you want your electricity to be generated. Coal remains perhaps the cheapest, but if you are willing to pay the higher cost you can be green. In some cases, we are now seeing starting to see select renewable energy sources as the cheaper option.
If you recall, much of the material in the Transportation Lesson dealt with the consequences of our vehicle use. This page provides a quick visual refresher of that material most directly to pollution in the form of acid deposition. If you don't know why it is being shown go back and re-read the lesson.
You know the deal with these coverage maps by now. For an interactive version of this map, go to the Exam Three Study Guide module.
Accessible Version (word document) [215]After looking at this map, please take the L10 quiz.
[Dr. Mathews is wrapped in a thick coat and sweater while wearing a wool snow hat.] Dr. Mathews: It is a beautiful day in Happy Valley. It's early February, the sky is blue (Tyndall Effect), the sun is shining brightly, and I haven't had to shovel snow yet. [Dr. Mathews takes off his hat, jacket, and sweater as he continues talking.] In fact it is so warm I haven't to need my hat, I don't need my jacket, and it is even warm enough that I don't need my wonderful hand knitted sweater; made with loving care by Ellen Jane Mathews my Grandmother. It's sixty degrees out. Students are walking around in their shorts, it's beautiful weather. It's a great day to be alive. Why is it this warm? Is it something to do with the carbon dioxide that we have been emitting since the industrial revolution into the atmosphere? Is it the greenhouse effect gone wild? Is it global warming, is it climate change? What are all of these things and what are we doing to combat these things? You are going to find out later in this lecture. [Video ends]
There is a connection between energy use and the environment. The climate we experience locally is not merely the results of our local behaviors and weather patterns, but is also linked to the regional and global patterns. As this realization grows, so too does the need for governments to address the serious climate issues of our time.
The purpose of this and the next lesson, is to provide you with an opportunity to increase your awareness of the energy and climate-related issues and challenges facing the world today.
You'll be successful in lessons 11 and 12 once you have demonstrated that you can do all of the following:
Question: So are you concerned with the impacts of climate change?
Click for some additional information.
Text Version [216]
Photosynthesis is the process by which plants absorb the sunlight, store it, and convert it into energy to grow and survive. It is represented by the following equation, where the plant takes in carbon dioxide and water, stores and uses the glucose to grow and live, and releases oxygen back into the environment.
6 CO2 + 6 H2O – energy →C6H12O6 + 6 O2
The energy is supplied by solar energy (sunlight). The glucose (C6H12O6) is used by the plant as a storage medium for the energy. As the plant grows [217] it will use the glucose to supply the plant with energy.
When plants die, this process simply works in reverse.
C6H12O6 + 6 O2 – decay → 6 CO2 + 6 H2O
Walking through almost any forest is the best way to witness the decaying process in action. The ground is generally strewn with dead and decaying leaves, limbs, branches, and sometimes entire trees. If they did not decay, we would be faced with a serious dead-tree population problem in our forests. Then imagine the scope of this problem times millions of years. This helps illustrate the nature and the value of the carbon cycle.
However, in Pennsylvania about 320 million years ago (and even today) the forests did not decay. Instead, the trees fell into swamps (bogs) and were protected from the decay process. Eventually, these trees formed coal. In the oceans, plankton and algae went through similar processes. There, the stored solar energy eventually formed oil (protection from oxygen at the bottom of the ocean, with sediment burial). Now as we use the fossil fuels (combustion) we release CO2 (a greenhouse gas) back into the atmosphere.
Listen to this audio file about Bear Meadows [218]. (Text Version of Bear Meadows audio [219])
Swamp Audio: Text Version (click to reveal)
Dr. Mathews: For those of you who are close to University Park there aren't swamps very far away. If you go to Tussey Mountain and keep on going and follow the signs for the nature area you will come across a very small swamp (or technically, a type of bog) very close to State College. It is a very interesting drive and a very interesting ride. But it is still going on. The process that was very important three-hundred million years ago in this region for a large quantity of coal that was formed, is still happening today. It is just that to form the crude oil and to form coal and natural gas it is such a long time process that these swamps won't be of any use to us because we cannot afford to wait that long. But go and take a look around. They are very beautiful. Essentially the key ingredient is a relatively stagnant water supply because that way it has a low oxygen content. And if it has a low oxygen content, that is what's important to the decay process. Look at the equation. You need to have oxygen. If you can protect the system of oxygen then only certain bugs will be able to nibble at these various components of this organic material.
The carbon cycle tells us that CO2 in the atmosphere is in equilibrium with the CO2 in the oceans and CO2 in the atmosphere is also in equilibrium with the CO2 chemically bound within minerals (carbonates like CaCO3 calcium carbonate, otherwise known as limestone).
Equilibrium () indicates that eventually the chemical reaction will balance such that the forward reaction and the backward reaction both occur at the same rate and so at certain conditions, a certain ratio is achieved (for example 60:40 or 60% of a reactant on the left-hand side of the reaction and 40% in another chemical form on the right-hand side of the reaction). The key issue, however, is that the equilibrium may be reached slowly (thousands of years) or very fast (a fraction of a second). Kinetics decides how fast the reactions will occur (recall the discussion on catalytic converters).
The lifetime of greenhouse gases can be very long (slow to reach equilibrium):
Thus, burning fossil fuels will increase the concentration of the greenhouse gases in the atmosphere, and enhance the greenhouse effect, which in turn will increase the global temperature.
Climate Change is the preferred term to describe the rapid changing of the climate that we (the planet) are experiencing mainly since the 1900s. It is related to global warming.
Global Warming is the increase in temperature (generally) that has been occurring mainly since the 1900s. The issue, however, is not simply, that on average, the planet's temperature is warming. Rather, if you agree that the climate will get warmer, then it makes sense that the warming will affect the water cycle and that, in turn, (coupled with a warming) will influence the climate. Global warming is the often used term, but not by my students who know better — climate change, please!
Not all of the areas of the planet are likely to experience a warming. Some areas will experience a cooling, so climate change is the preferred terminology. Also warming in some areas may prove beneficial but without water this benefit will be lost. Alternatively, if there is a change in the precipitation (rain, snow, hail, etc.) pattern as you would expect if the temperature changes, then too much or too little water can both be disastrous. Thus we are experiencing change, not just warming! Some plants will grow quicker and larger, while others will not grow, so change is the key term.
The greenhouse effect is a highly beneficial process where the planet is warmed by greenhouse gases helping to trap some of the radiation that would have otherwise escaped back into space. Without greenhouse gases the surface temperature of the planet would be an average –18 °C (0 °F)! Chilly.
Greenhouse Gases are gases (in the atmosphere) that will absorb infrared [221]radiation (l [222]earn more about the electromagnetic spectrum [222]) [223]. Naturally released greenhouse gases include water (H2O), carbon dioxide (CO2), methane (CH4) & nitrous oxide (N2O) (a.k.a. laughing gas). Ultra Violet radiation (UV) will penetrate the atmosphere and a portion will be absorbed by the surface of the planet. When radiated back into the atmosphere it will be in the form of Infrared radiation (IR), thus some of this IR radiation will be absorbed by greenhouse gases. Being dumb molecules they don’t know which is up or down so after “doing their thing” they get “tired” and re-emit the IR radiation, a portion of which goes back to earth warming the planet. (Click on the molecule to see the molecule "Doing its thing" [224].) "Doing their thing" implies the excited state of the molecule. Through a series of bond stretching, bending, wagging etc. the molecule uses the energy (without significant losses). This is an example of methane going through its excited states within the IR spectrum. The IR spectrum of an unknown gas can be used to identify some gases or their relative portions.
Providing the concentrations of the greenhouse gases remain the same, other than [225]normal seasonal temperature fluctuations, [225] the planet will have a relatively stable temperature year to year. Of course, there are natural cycles in place that both remove and replace these greenhouse gases in the atmosphere. The National Academy of Science has a nice graphic explanation of the greenhouse effect [226].
It is tempting on a very hot day to say: “that bloody global warming again!” But that would be incorrect. We do not say: “bloody ice age” on those very cold days (although predictions were made when I was a lad that we were about to enter a new ice age!). The weather is an event that is going to change and the temperature variations can be dramatic. Climate change occurs over a much longer time frame: at least decades! When we see a change in the average temperatures over the last 20 to 30 years then that is climate change. Climate change might influence the weather, stronger storms, more or less rain, but single weather events cannot be attributed to climate change although there is progress in linking climate change to storm strengths, etc..
If we focus on the anthropologic emissions of CO2 we can find out where the CO2 is coming from and then we know who is to blame! The allocation of greenhouse gases is clearly shown indicating that the transport , industry and electricty generation is now the prime contributors (emissions from electicty generation have decreased with fuel switching away from coal). Utilities are easier to impact as there are far fewer utility plants than vehicles (~250 coal fired utilities down from ~500, there are 96 or so nuclear utilities, etc.) The recent increase in shale gas extraction has contributed to a significant reduction of CO2 from coal as utilities switched to the now cheap natural gas. For the U.S. to move forward with greenhouse gas reductions: transportation with need to be decarbonized or at least have much lower emissions (you know how to achiveve that — right?)
This should come as no surprise. Recall that we obtain energy from the following reaction:
C (in oil or gas or coal or biomass) + O2 →
CO (2/3 of the energy) is from this step and then CO →
CO2
So when we combust the fossil fuels, biomass (wood), gasoline, or diesel we release CO2 into the atmosphere. Since much of our energy comes from the chemical energy stored in fossil fuels, we release a great deal of CO2 into the atmosphere. Methane has more hydrogen than coal and so less CO2 emissions.
So I can blame the utility industry and the automotive industry, right?
Look in the mirror. You use electricity to power this computer, light your surroundings, and play that stereo (turn it down it is too loud!). You drive/fly and so you are to blame (me too). What we need is a technological solution, or a change in our behavior. Both are not easy to discover (technology) or implement. There is also a significant impact on changing land use, and natural events such as volcanoes or forest fires.
This is a cool graphic that examines the greenhouse gas contributions to the temperature rise [227]. (Make sure you scroll down to see the animations on the data). It also shows the contributions from some of the other initial theories for why climate change was occurring.
Let us look at the data! What do you think has happened since the Industrial Revolution when most of the combustion of fossil fuels has occurred? Climatologists have been keeping records of the composition of the air around the world for about 60 years now. One of the longest recordings is from the Mauna Loa Observatory [228] in Hawaii.
Why the roller coaster ride? Recall the carbon cycle has both photosynthesis and decay occurring, so in the Spring when plant life is growing, the CO2 concentration falls, while during the Fall and Winter the decay process dominates and the CO2 concentration increases.
Happy with that explanation? Here is the updated data, the trend has continued
If you answered no, give yourself a pat on the back. Remember that it is Winter in Australia when it is Summer here. So how can the CO2 concentration cycle? The Southern hemisphere is mostly water and so the summer/winter activities in the northern hemisphere dominate.
SPRING: (Image of the tilt of the earth in the spring) In this configuration, the earth is not tilted with respect to the sun’s rays (The earth in this picture is actually tilted towards you as indicated by the fact that you can see the North Pole – green dot). Therefore, radiation strikes similar latitudes at the same angle in both hemispheres. The result is that the radiation per unity area is the same in both hemispheres. Since this situation occurs after winter in N. Hemisphere we call it spring, while in the S. Hemisphere it is autumn. This occurs on March 21.
SUMMER: (Image of the tilt of the earth in the summer) When the N. Hemisphere is tilted towards the sun, the sun’s rays strike the earth at a steeper angle compared to a similar latitude in the S. Hemisphere. As a result, the radiation is distributed over an area which is less in the N. Hemisphere than in the S. Hemisphere (as indicated by the red line). This means that there is more radiation per unity area to be absorbed. Thus, there is summer in the N. Hemisphere and winter in the S. Hemisphere. This situation reaches a maximum on June 21.
AUTUMN: (Image of the tilt of the earth in the autumn) In this configuration the earth is not tilted with respect to the sun’s rays (The earth in this picture is actually tilted towards you as indicated by the fact that you can see the North Pole – green dot). Therefore, radiation strikes similar latitudes at the same angle in both hemispheres. The result is that the radiation per unit area is the same in both hemispheres. Since this situation occurs after summer in the N. Hemisphere we call it autumn, while in the S. Hemisphere it is spring. This occurs on September 21.
WINTER: (Image of the tilt of the earth in the winter) When the N. Hemisphere is tilted away from the sun, the sun’s rays strike the earth at a shallower angle compared to a similar latitude in the S. Hemisphere. As a result, the radiation is distributed over an area which is greater in the N. Hemisphere than in the S. Hemisphere (as indicated by the red line). This means that there is less radiation per unit area to be absorbed. Thus, there is winter in the N. Hemisphere and summer in the S. Hemisphere. This situation reaches a maximum on December 21.
Okay, so we know the concentration of greenhouse gases has increased in the atmosphere over the last 50 years (Keeling curve and other observations) so what has happened with the global temperature over that time period? It has increased but here is a difference in the increase between the land and the ocean?
[Video opens with two glasses of soda. The one on the left has very little air bubbles rising to the top. The one on the right is bubbling at a much higher rate.]
Okay, so now we realize it is a complex issue. Other causes have been suggested, such as increased solar activity warming the planet, which warms the oceans and reduces the amount of CO2 that can be held in the water. (huh????)
The important fact is that the temperature of the planet has increased by about 1 °F during the last 100 years. Phew, I thought we were in trouble for a minute! Why all the fuss over about 1°F?
If we look at longer timelines we can determine that this rate of change is very rapid! The planet goes through these changes anyway, but very slowly, usually. After all, the geography of large areas of North America is a result of ice ages and glaciers scouring the earth. So how do we know what the temperature was hundreds to thousands of years ago, or what the CO2 levels were?
Some of the trees in the world live long, long lives and by looking at the thickness of the rings as well as the number, the relative climate can be determined. This technique was used to show that the first few years of the Jamestown colony were very dry which contributed to their near starvation. While this technique can only go back a few hundred years it is still very useful for looking back at climate history over those years. The image shown indicates a little trouble with a forest fire in this tree's history. Here at Penn State, there is a tree ring laboratory, where this image was obtained (with permission I might add!). Recall that trees grow because of CO2 (the carbon cycle). They also grow faster with more CO2 so some believe that we should treat CO2 not as a pollutant but rather as a fertilizer for the trees. More CO2 may well produce quicker growing forests and other crops!
Listen to an audio track about wood from the lake [229].
Wood from the Lake Video: Text Version (click to reveal)
Dr. Mathews: When sailing ships from Great Britain found the continent of the United States they were very happy to find one thing that was desperately needed, trees. Very, very large trees. Trees, remember, are very important for military reasons. Remember England is an island, so if you want to go out and conquer the world, you need a navy. A navy requires wood. And the bigger the trees there are, the bigger the boats you can build with larger guns. And so we were very happy to find very large trees in American which we could take back and use in our shipbuilding processes. The trees you see here now in Pennsylvania are essentially the third generation of clear-cutting. Originally the forest would have been very different. And in fact there is a company out, I think, in the lakes of Minnesota, where they found large submerged logs. And they would bring them up with cranes and sell them at market. What makes this wood so valuable and worth the effort, is it was part of the original forest, the first clear-cutting. In those days a canopy was very very thick. And so the trees tended to grow slower because they received less light. Therefore, the rings were much closer together. And the grain or the beauty in the wood in the furniture making process is much richer and highly more valued. And so these trees could be worth a hundred thousand dollars. A hundred and twenty-five years later after laying in the bottom of a lake.
The air temperature influences the size of snowflakes. Warmer snow has larger flakes. Thus, when you look at snow after digging a hole to sit in you will see layering. This is useful information for the prediction of avalanche conditions. As the snow ages and more snow is deposited on top, the snow will form ice. There are a few locations in the world where the ice is very thick and hence there is data for thousands of years in the ice cores that they drill and bring back. You can also see the volcanic dust from long since past eruptions and date the ice with known volcanic events, or simply count the ice layers as you would rings on the tree (size of the snowflake influences the optics of the ice, which is related to the temperature).
Another very useful aspect of the ice is small air bubbles trapped within. These are miniature time capsules that contain a sample of the air from when the snow fell. Thus, we can determine the levels of CO2, methane, or other gases in the atmosphere. We have some faculty here at Penn State that do this. Dr. Richard Alley!
In the same way that ice cores can reveal both temperature and a measure of the gas concentrations, coral can indicate the temperature and the concentration of CO2 in the ocean, which is related to the concentration of CO2 in the atmosphere. Coring the coral looks like a much better job than coring the ice! As the coral has a slow growth rate there are again thousands of years of information available in certain locations. Unfortunately for the coral, the temperature sensitivity will cause their loss in some locations, if it gets much warmer.
Here is some data from a longer time period [230]
It is not only the burning of fossil fuels which is impacting CO2 emissions. Changing land use is also an issue.
Dr. Mathews: I obtained my first degree from Nottingham Trent University. It is a wonderful university and a great city of Nottingham. And of course with the drinking age being 18, the pubs featured very heavily in our lifestyle. One of my favorite pubs was the Trip to Jerusalem Inn. This claims to be the oldest pub in the country. The story goes that the knights, on their way to Jerusalem, came out of Nottingham Castle, turned right, went to the bar to have a beer, and then continued on for the crusades. If they did the same trip now, they would go past the statue of Robin Hood. The city of Nottingham is very much synonymous with Robin Hood and his merry men. Interesting though, if you would like to go to Sherwood Forest from Nottingham it would take about a five day walk to get there. Nottingham Forest, or Sherwood Forest more correctly, has shrunk considerably since the day of Robin Hood and his merry men. Land changing issues are very important. In this satellite photograph you can see areas where roads have come in and the forest is being cleared and logged. We have an insatiable appetite for wood. Just look around you. I am sure you could probably see a wooden door or a wooden desk or a wooden chair. So very interestingly when we cut down these forests we release a great deal of CO2 into the atmosphere and of course that contributes to climate change. On the global scale now, Europe doesn't commit a great deal of CO2 from land change use issues. What happens is we have already cut down most of our forests and those that are remaining are protected. However, it is the developing nations and some other nations where significant land changes are still occurring and it is all going to contribute to climate change. Remember, these forests are great big CO2 sinks, they are self propagating storage areas for carbon monoxide.
As I ponder the seasonal event of raking leaves, I wish I had a smaller garden, or fewer trees. My house is a typical size for the State College area at about 0.3 acres. That does not sound like much (until you rake leaves), but there are lots of houses. As the population grows and economic development occurs, new homes are constructed. So every home on a "Greenfield" site takes away a chunk of land that used to hold biomass. My house was built in 1972 on what was once farmland. Going further back in time, the whole State College area was forest. Indians (Native Americans) lived on the land and killed settlers in this area. Look at the map sometime and see how many "fort somethings" there are.
And we're not just talking about land for residences - this includes roadways, open parks, schools, businesses, shops, natural products and agriculture. You've heard this before...."They paved paradise, and put up a parking lot"...Joni Mitchell
As more forest is clear cut there is less of a carbon sink to contain carbon and this influences CO2 emissions, particularly if burning is the means to "clear cutting" of the forest. This issue of land change is a major issue in the developing world. Here in the US, our agricultural productivity has risen so that the government pays farmers not to farm the land! Deforestation also causes loss of environment for endangered species, runoff, loss of topsoil through erosion, and deadly mudslides in locations such as Haiti.
As a lad, I spent many a day in the field baling hay and working in the garden. I hated it! I brought a tear to my father’s eye the day I told him I was going to Astroturf the whole lot the day after he died! It took lots of time and nurturing to grow the vegetables and other foodstuff and I would rather have been elsewhere. To get the prize-winning leeks, the ground had to be fertile and you also needed the right amounts of sun and rain (not usually a problem in England). We had good seasons and bad. The weather certainly had an impact. There were seasons where we needed rain and plenty of days when we wished it would stop raining. If the planet warms up, and/or there is more carbon dioxide in the atmosphere the plants will be happier and grow quicker. Carbon dioxide, after all, is where the mass of the plant comes from. Plant an acorn, wait 50 years, and see how large the oak tree grows. Where does all the mass come from? Not from the ground, but from the atmosphere: good old CO2!
But if the planet warms, then it is likely that evaporation will increase and that will impact the distribution of precipitation. Change here is very important! Wheat, for example, is grown in the heartland of America because that is where the conditions are appropriate. While initially, at least, productivity might increase with warmer temperatures, productivity will decrease and the appropriate location for growing wheat may move across the border to Canada.
Listen to an audio track [232].
Text Version (click to reveal)
Dr. Mathews: How plant life adapts to more CO2 is going to be interesting. Some people see it as a great benefit. That more crops will be able to feed the planet, not something we do particularly well right now. Simply that the forests and the other crops will simply adapt, grow quicker, and that the planet will take care of itself. That it has mechanisms in place to try to reduce drastic change. Certainly, we expect certain plants to grow quicker and certainly, some are going to be quite happy about the increased concentration levels of CO2. We will wait and find out what happens. But again fascinating subject.
Imagine growing rice without a paddy, hard to do! It is not all doom and gloom, climate change may prove to be beneficial in certain areas for certain crops; perhaps doom and gloom is appropriate for some other crops, however. We could always adapt and plant other crops, the developed world regularly irrigates (providing we can find the water or divert the occasional river). Famine in other locations, however, may be a very real threat. The combination of changing temperature, changing precipitation, and the response of the crop are the important factors.
I was one of the few who liked "Water World" with Kevin Costner; I thought it was a decent movie. The premise was that the oceans had risen and flooded the whole planet with only small isolated fragments of land being the “Holy Grail." One of the big fears is that with climate change we might see a similar event (although not as catastrophic). When water warms, it expands. If the temperature changes then we should expect the sea level to rise (although some places on the planet will be cooler, the overall trend is a warming one). Glaciers will melt (although new ones might also form), also adding to the volume of water in the ocean.
If you look at the wildlife in England and France, for example, you will find them to be similar, even dating back to the dinosaur fossils. Presuming that they did not swim across, means that there was once a land bridge where the English Channel now is. There are many places where what is now land at one time was under the ocean. Odds are that where you are now is on what was once ocean (a good chunk of North America was once undersea). So this is not as fantastic an idea as it may seem.
Of course, you should worry if you are close to the coast. A high percentage of most populations are close to the coast as shown in this image from NASA. Certain island nations are also in the “hot seat” with regard to sea level rise.
Listen to an audio track about land reclamation [233].
Text Version (click to reveal)
If sea level continues to rise, then obviously there is an issue with flooding of the land. If you think about the Netherlands, you generally think of Holland and the windmills. The windmills are there to keep the land dry. Much of the territory is actually recovered from the sea and so there is an extensive system of dykes or walls that keep the sea out and these windmills continually pump out the water. Now that's a very expensive undertaking and if you're a poor nation, you can't afford healthcare and you can't afford education for your populace, it's very unlikely that you're going to be able to afford to have an extensive system of dikes to protect your island chain. Places like Indonesia where you have high mileage of coastline and poor populations, India, China, etc., that's where the problems are going to be. The rich, industrialized nations will be able to have expensive engineering processes to try to protect the cities from flooding. Such as the one that London has done back in the early 1980's. But it's a very expensive operation and so again, it is the poor that are going to suffer if indeed we are going to see an extensive raising of the sea levels.
Below is an image of the US at night taken from space. Where is all the light coming from? Click on the image to see the concentration of the US population. What is the relationship between the two?
Warmer and wetter environments, or warmer waters, might well allow diseases to enter environments not previously exposed. Infestation may increase; tropical diseases associated with warmer climates might well appear in US cities. Dengue is one example that is relatively rare in the Northeast but we might observe an increase as mosquitoes continue to be active for a greater time period because of the climate change. It is a nasty viral disease that causes rashes and soreness in joints - very unpleasant!
Water quality is another issue that will be influenced by climate change. There may be more algae blooms and the possibility of water-borne diseases may increase. Increases in temperature or even increased snowfall (remember change is the issue) will cause more deaths from the extremes of heat or cold. Air quality may also be influenced. All in all, many negative impacts on our health are predicted.
What is certain, is that climate change is occurring! That is about the only certainty when this subject is debated. There are a lot of uncertainties:
Why it is happening: Text Version (click to reveal)
Dr. Mathews: While we do agree that climate change is occurring, we are still debating what to call this. Certainly we have seen natural changes in the temperature and precipitation patterns in the past. The big debate is this anthropologic related due to man's activities or changing land use, the removal of the forests, from occupation or crops growing or is it perhaps a very natural event that is occurring as we have seen previously in the history of the planet. So we are still going to debate this. There are still a lot of interested parties however, saying that we don't know enough and that you don't want to make too many decisions that are going to impact the well being economically of the United States when there is so much uncertainty.
Impact of Snow and Ice Melting: Text Version (click to reveal)
Dr. Mathews: One of the reasons things are so uncertain comes because of feedback loops. Imagine this scenario, it warms up, snow melts. Because the snow melts it reveals more land. Well the land will warm up more because it is receiving more energy. When there is snow or ice on the ground, when there is sunlight, much of it gets reflected back up into space. When you go skiing, one of the key items of your equipment is goggles. Snow blindness is a very real threat because so much more light gets bounced from the surface into your eyes that in fact you can actually go blind. It is a very similar things with clouds. World War II pilots would wear sun glasses and if they are fighting in Europe it is not because of the English weather. When you are flying above clouds, again a lot of that light gets reflected back off the surface of the clouds because of the whiteness and it impacts how much energy reaches the surface of the planet. So back to the snow, snow melts, revealing more land the land warms up, the climate warms up, more snow melts. More snow melts, revealing more planet, more warmth from earth's land. This is a cycle. And it can happen the other way. We think ice ages, what happens is it snows, more energy is reflected. Then it gets warmer. Then it snows some more, more energy is reflected, the planet gets colder. It snows some more. A lot of these feedback loops will be happening and they can have a very drastic on how one assigns climate change models.
Predictions: Text Version (click to reveal)
Dr. Mathews: Predictions are, well, predictions. We are not very good at telling the weather. When you are watching the Weather Channel they will tell you four days in advance and when there is a significant snow event coming we will see the snow falls change on an hourly basis. From the predictions from anywhere from we are going to get two feet of snow to we are going to get less then an inch. We are not very good at predicting the weather. What is going to happen is we are going to know if we are right 20, 40, 50 years from now. And there is a lot we don't understand. And the fear is that we are maybe jumping in too early, maybe by some. Others say the risks are worth it that we are probably going to help reduce pollutants in other areas as well and increase our energy efficiency. And it is going to have other benefits. But not much is certain in this area. So predictions, are well, just that. The computational models we use vary very widely from location to location and model and the assumptions that go into these models. So it is a very interesting subject.
Well, perhaps there are some other certainties. There will be a cost ($) to reduce pollution, or reduce energy use!
As more research has been performed there is much greater certainty that climate change is the result of human activities. From the Intergovernmental Panel on Climate Change (IPCC):
Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.
The reason that we have such a high quality of life in the United States is directly related to our energy usage. Washers and dryers, dishwashers, microwave ovens, garage door openers, DVDs, big screen televisions, personal automobiles, cell phones, and computational communications are all examples of devices which we would find hard to give up. How the energy is used in these devices (efficiency), the device numbers (energy demand), and how that energy is produced (coal, nuclear, wind, etc.) will impact the pollution that we produce. If you consider CO2 to be a pollutant (some well-respected scientists don’t) then the energy to run the country, goods, and services is all for our benefit so you are to blame.
We can be more efficient or use renewable energy but it will cost more. We already use $1,300 worth of energy for everyone in the US (the bills that you pay, such as electricity, gasoline, natural gas etc.). Bottom line: Your high quality of life comes with a financial and an environmental cost.
We lead in the category of most CO2 emissions per person (per capita) among the big emitters (there are some small nations with higher emissions).
What do all of the countries listed have in common? What type of countries are missing? Is it fair to other countries that we pollute internationally on this scale?
Industry is one of the major contributors of CO2 emissions. Here we include utilities (those sites that produce electricity) and other energy-intensive industries such as cement, steel, and paper manufacturing. Goods are being made because we want them!
It is not just the movement of the populace around the country (about 13,000 miles per car per year) but also the movement of goods and services. We don't make cars in State College so they have to be brought to the marketplace (and all of their components need to be transported to the assembly plant). Bananas, oranges, and exotic fruit from around the world are delivered to supermarkets and dining establishments - to serve us! We are in a market-driven economy. We make stuff because we can sell it (at a profit). If there are no buyers, then no goods will be made.
Commercial buildings such as offices and supermarkets, some of which are open 24 hours a day (I love the service economy that we have in the US!), need to be heated, cooled and require security and internal lighting. All of these activities require energy. Often, as the space is quite large, they will need a lot of energy.
Heating (in the NE), cooling, hot water, TV, garage door openers, refrigerators, the list goes on.
You need to: plow, sow, plant, irrigate, spray, fertilize, harvest, process, and deliver your goods, all using energy. There is also considerable decay at the end of the growing seasons when the unwanted biomass is composted or burned off. All so you can get a Big Mac and fries!
The image map below is a visual overview of the main ideas contained in this lesson. Hover over the text for more information.
Accessible Version (word document) [239]
After looking at this map, please take the L11 quiz.
When it became evident that climate change may be occurring, there was the beginning of the movement (a series of meetings called the Conference of Parties —COP) that was responsible for the Kyoto meeting in December of 1997: a section of the United Nations was formed: The United Nations Framework Convention on Climate Change (you might see UNFCCC in some of the linked text). The first meeting was the “Earth Summit” in Rio de Janeiro, subsequent meetings set up the reduction strategies for climate change. The two most important meetings were held in Kyoto, Japan (the Kyoto Protocol) and in Paris, France (the Paris Agreement).
Reduction of six greenhouse gasses by some countries, to varied levels below their emissions of greenhouse gasses in 1990.
The treaty was to become legally binding when it was ratified by 55 Countries (they use the term "States") including the Developed Nations responsible for 55% of the carbon dioxide emissions from the Developed Nations group in 1990. This treaty was ratified in 2005 (Russia was the last necessary country to adopt it.) The United States has not ratified it yet (but we are bound by the agreement).
Just to confuse everyone (and so as not to embarrass developing countries) they use the terms Annex 1 parties (mostly developed nations) and Annex 2 Parties (mostly the developing nations).
An emission trading methodology was adopted to reduce the cost of compliance (but details on how this will work are not yet in place). A major victory for the US as we utilize this approach for SO2 and NOx emissions via the Clean Air Act of 1990 and its amendments.
Developing countries have a “right to develop” and so will not have to reduce or curtail their emissions of greenhouse gases at all.
Changing land use issues and natural carbon sinks (such as planting a forest) also impact the reduction levels assigned (and agreed to).
Sharing of technology (sounds a tad socialist to me and will be difficult to employ).
There is a great deal of uncertainty in how everything will work out.
The European Union is allowed to act as a “bubble” and redistribute the reductions to meet the overall reduction level required. Australia joined but then after a government change, left the agreement. The United States has not ratified the Kyoto Protocol.
More information is available (if you are interested) from the United Nations Framework Convention on Climate Change [240].
Recall that this was discussed when we covered acid deposition. Internationally, this will work well, as it will be cheaper to reduce emissions in other countries that are operating old, inefficient equipment than it will to reduce emissions from plants that are efficiently run. As CO2, unlike a lot of emissions, is global in nature, it does not matter that we are reducing emissions in India or China, we will still reap the benefit of slowing the pace of climate change. Many of the pollutants we discuss may be international in natures, such as acid deposition from Germany crossing into France or vice versa, they will not travel the globe and influence Australia for example. The long lifetimes of the greenhouse gases in the atmosphere allows them to travel extensively so their increase can be measured at the poles far from the point source of origin (your car, power plant, natural source, etc.) Ozone-depleting CFCs also are long-lived and tend to congregate above the South Pole.
As long as there is a reduction, the requirement is met, it's source is not important. However, there is a financial cost assigned with these reductions. The developing countries need health care, education, and clean water as a priority well above reduction in climate change. They can sell off emission reductions to the highest bidder (at a profit). Industry will be happy to buy these permits as long as they are priced below the cost of achieving the same reduction in their industry. More on this in the next part of the lesson.
We agreed to a reduction to 7% below 1990 levels. That does not seem to be too high, but there is a problem: emissions have been growing (as has the economy, followed by a downturn...).
The 7% reduction below 1990 levels looked like it may have ended up being a very significant 30% reduction from 2010 levels. There is a lot of speculation on how much greenhouse gases we emit because it depends on many factors, such as the economy, severity of the winter or summer, changes in the fuel mix. While the 7% reduction is high, a 30% reduction is staggering (7% from going to below 1990 levels and 23% estimated from the growth of the emissions). Actual numbers ended up being much smaller but we will not meet the goals, like many, many nations.
There is a significant change in policy when the Obama administration was replaced by the Trump administration.
Obama Administration
The U.S. managed to have very significant reduction but much was due to fuel switching from coal to natural gas for economic reasons rather than policy (although that did contribute).
Here is a good link to see what the US had agreed to [241] (take a quick look).
We have the ability to store CO2 in certain geological formations but there is a lot of uncertainty as to the viability and the cost. If we can prevent the emissions to begin with, we are going to be able to be in better shape. We discussed conservation earlier, but there is another option: going abroad to help out other countries to raise their efficiencies or even close down some of the older plants. But how does that help the US with her emissions?
Emission trading [243] (also known as cap and trade) was one of the key successes in the negotiations for the US. By going to other countries where the technologies are not already running at high efficiencies (for the application) then with new sensors, replacement parts, or enhanced monitoring and technology the efficiencies can be raised cheaply (at least in comparison to doing the same thing in the U.S. where the efficiencies and the monitoring is already in place).
To make sure that the U.S. gets the credit, the international trading system of emission permits for CO2 needs to be established. The U.S. hopes it will be a model similar to the SO2 emission trading model established in the Clean Air Act (1990). Bottom line: it will be cheaper to go abroad to developing countries and countries of the former Soviet Union and lower their emissions, pay for, and claim the credit for the emission reduction.
However, some early attempts at this have failed. The devil is in the details, such as the cap and incentives to get the system operational. The advantage is that there is a well-defined limit.
If the loss of carbon sinks is the issue, then why not replant the forests? This is actually a great idea (providing you have the land, not likely to work in New York, New York). The Australians were very keen on having carbon sink count as a means of offsetting CO2 emissions and it was included in Kyoto protocol.
After all, the fossil fuels were at one point in time locked away in biomass. By returning them to that state we take the greenhouse gas carbon dioxide out of the atmosphere where it might be contributing to the warming of the planet. If we really want to extend our energy use then we can cut the trees down, burn the biomass and as long as the trees are replanted it is a carbon dioxide neutral system. But wait, it gets even better:
We can use other plants too such as Corn or Sugarcane (warmer locations such as the Caribbean). Then instead of burning the fuel, we make booze! Well, perhaps not the booze we would want to make. We can make ethanol (or methanol—but you cannot drink methanol) and instead of it being in the rum (Bacardi and Don Q—made in Puerto Rico) we can make pure ethanol and use it as a transport fuel. Does this ring a bell? Remember Brazil: 3% gasoline in the ethanol to prevent the ultimate drink driving problem: One for you (car) & one for me! Sugarcane is already biomass in the sense that the cane is crushed to squeeze the sugar water out, the stalks are dried and then used to fuel the fire for the rum making process.
Recall that biomass has multiple advantages:
There are many concerns, however, the food vs. fuel issue and the energy intensity of growing certain biomass (use of natural gas, derived fertilizer for example, as there is not enough manure).
The CO2 is not the only gas that is contributing to the increased concentration in the atmosphere. Methane (CH4) is also being released into the atmosphere and as it is a more efficient greenhouse gas (one CH4 molecule is roughly equivalent to twenty-one CO2 molecules). So if we can plug the leaks that would help mitigate climate change (possibly).
Recall that coal mines can be a source of methane leaks. Two gigantic coal mines in Russia, for example, are responsible for much of that country's methane release. Capturing the methane and using it also helps lower greenhouse gas emissions (if it is replacing coal) because it has a higher efficiency (combusts at a higher temperature).
Animals, particularly cows, are another source of methane! I forget how many stomachs a cow has, my nephew (8-year-old) says 4! While processing the food they eat, the average cow will emit 280 liters of methane gas a day or about 119 pounds CH4/head/year (Johnson and. Ward, 1996). There is not much we can do to capture this short of a rather vulgar bovine attachment. However, if we were to be vegetarians, you can feel better about your personal contribution to the increased concentration of greenhouse gasses. But if you also eat a lot of rice (I love rice, being English it is our national food—with a good curry of course) then you help to produce a significant amount of methane. The rice paddies require fertilization, and being a stagnant water supply is low in oxygen, and so methane is produced.
Bottom line: Teriyaki Beef with rice (the special at Spats last week — Splendid) is not the most environmentally friendly dish you can have! I should feel more guilty about driving the car to the office, that trip had the greater contribution to my greenhouse gas emissions!
Sequestration is locking something away. With CO2 we wish to lock it away so it does not enter the atmosphere and contribute to climate change (possibly). So all we need is a location where high volumes of CO2 can be stored–trivial, right?
There are not too many locations where there are massive holes in the ground, but there are other options:
Most will be used in the US where appropriate. However, there is a significant and costly catch: we do not get pure carbon dioxide out of the stack of power plants! What goes in: fuel and air. What comes out: products of combustion and air. The products of combustion are mostly carbon dioxide and water with lesser quantities of NOx and sulfur dioxide, etc. The air that we used is where the problem is. Air is mostly nitrogen. We want the oxygen but have to let the nitrogen tag along unless we can afford to separate them (\$\$\$\$\$\$). For every 1 mole of oxygen, we get about 6 moles of nitrogen. We also add more air than is necessary to help the mixing process, necessary for combustion to take place. So the nitrogen that goes into the system comes out again and we will have to separate the carbon dioxide from the other gases, oxygen (from the excess air), water (product of combustion), and nitrogen (\$\$\$\$\$\$). In the flue gas image shown to the right, the molecules are shown very close together in an unrealistic representation (too high a density) for viewability.
We have the technology, but part of the cost of sequestration will be this separation process. If we did not separate the gases, we will have to pay more for the compression, transportation, and pumping (\$\$\$\$\$\$).
Watch the (4:46) video below. It is a good simulation overview of the carbon capture and storage approach.
Recall the carbon cycle: The key to this issue is waiting long enough for the CO2 in the atmosphere to reach equilibrium with the CO2 in the ocean, at which point a significant quantity of CO2 will have been "removed" from the atmosphere - the problem is time. As my daughter likes to say on our road trips "it is taking too long!" That is the case here. We can not afford to wait. However, the good news is that the ocean offers significant CO2 storage capabilities (for long-term timelines).
There are 3 approaches to this process:
Remember how crude oil is formed? If there were more "bugs" in the ocean (phytoplankton) then as they grow and reproduce they will absorb CO2 (remember this is photosynthesis)! They will die and decay but providing there are more of them and they are self-replicating (whatever the outcome of plankton sex is) then there will be more carbon in the ocean and less CO2 in the atmosphere. This is a carbon sink (more on this later). The ocean "bugs" can also grow shells, which they obtain from the dissolved minerals in the ocean and dissolved carbon dioxide. "She sells sea shells on the sea shore!" Try saying that 4 times as quickly as you can. So the shells can also capture CO2 for long periods of time.
Check out the Monterey Bay Aquarium Research Institute [244]) for more information about this topic.
If you are a visual learner and would like to see liquid CO2 fill a beaker underwater (considerable depth): click on the image below to download and watch a short video.
But there is a lot of concern about perturbing the ocean so this is not a very likely solution.
While oil fields are not exactly a great big hole in the ground (remember it is a porous rock that contains the oil), there are lots of small holes and they can be filled with CO2. If the field is still producing it has the added effect of enhancing the oil extraction process (enhanced oil recovery). Remember that associated natural gas helps to provide the pressure so that the oil will freely flow out of the ground (so you do not have to pump). This is very similar and is a technology that is being used.
If the oil field is not producing then you will not obtain any extra oil or gas but you might benefit from capping the abandoned natural gas wells that are leaking methane into the atmosphere.
According to the U.S. Department of Energy:
Saline Formations. Sequestration of CO2 in deep saline formations does not produce value-added by-products, but it has other advantages. First, the estimated carbon storage capacity of saline formations in the United States is large, making them a viable long-term solution. It has been estimated that deep saline formations in the United States could potentially store up to 500 billion tons of CO2.Second, most existing large CO2 point sources are within easy access to a saline formation injection point, and therefore sequestration in saline formations is compatible with a strategy of transforming large portions of the existing U.S. energy and industrial assets to near-zero carbon emissions via low-cost carbon sequestration retrofits.
Assuring the environmental acceptability and safety of CO2 storage in saline formations is a key component of this program element. Determining that CO2 will not escape from formations and either migrate up to the earth’s surface or contaminate drinking water supplies is a key aspect of sequestration research. Although much work is needed to better understand and characterize sequestration of CO2 in deep saline formations, a significant baseline of information and experience exists. For example, as part of enhanced oil recovery operations, the oil industry routinely injects brines from the recovered oil into saline reservoirs, and the U.S. Environmental Protection Agency (EPA) has permitted some hazardous waste disposal sites that inject liquid wastes into deep saline formations.
The Norwegian oil company, Statoil [246], is injecting approximately one million tons per year of recovered CO2 into the Utsira Sand, a saline formation under the sea associated with the Sleipner West Heimdal gas reservoir. The amount being sequestered is equivalent to the output of a 150-megawatt coal-fired power plant. This is the first commercial CO2 geological sequestration facility in the world.
Text is from the fossil energy sequestration page of U.S. Department of Energy.
I get to do some of this in my research with colleagues here at Penn State and elsewhere. Coal is a wonderful material! While it looks solid, if you select the appropriate rank of coal, the structure is full of very tiny holes, so small they are too small to be holes–so we call them pores. The very small pores are known as micropores and "here is where the magic happens" (for you celebrity crib fans). There are larger pores, and also very large pores or cracks in the coal, which are very useful for increasing the permeability (speed of access of the gasses into the coal).
In the gas phase (there are three phases: solid, liquid, and gas for most things) the molecules or CO2 are bouncing around. We can increase the pressure (more gas molecules in the same volume as before) but that takes work. The molecules like their space and anyway we are decreasing their entropy. But if we put a molecule of CO2 into a coal micropore there is an attraction between the matrix and the CO2 molecule. Now the CO2 does not need as much space, it wants to associate with the coal and thus we can put in more CO2 into coal than we could into the same volume of empty space (bloody marvelous!).
There are a couple of other advantages too. Remember that methane is often in these pores too (if we are at the bituminous rank range), well, CO2 acts like an invading army and kicks out the methane (it competitively replaces the methane molecules). Thus, you could sequester CO2 into a deep coal seam, collect the methane that is released from the coal (coal bed methane), combust that and put the CO2 formed back into the coal seam. Thus forming a closed loop of emission free (CO2 anyway) electricity for as long as the methane lasts. As we have lots of coal, much of it is close to large point sources of CO2 (such as a power plant), then this all makes sense.
There are only a couple of minor details, the main one being cost. If the pumping and separation of the CO2 costs $ then the price of the electricity generated will increase. We are not yet in a competitive region for any of the sequestration technologies (maybe enhanced oil recovery). Selling methane certainly helps to lower the cost of sequestering CO2 into coal but the cost is still too high. There are a couple of locations where we are currently pumping CO2 into coal.
Details here if you would like to know more.
If you live on campus you would have seen OPP (Office of Physical Plant) driving about with the slogan "bright students dim the lights" on the side of the trucks. If we conserve, we use less energy, if we use less energy we use less fuel, if we use less fuel then there is less pollution (particulates, NOx, mercury, SO2, CO) and if we consider CO2 a pollutant (many do not) then we can have a slower pace of climate change. As we are using more and more energy each year, conservation tends not to be a reduction in the quantity of energy we used but rather a reduction in the growth of energy that we use each year. We can achieve a reduction of energy if we enter a significant depression, (look at the dates) and we can use less energy if the weather is kind (warmer winters and cooler summers).
Bottom line: we can conserve but we cannot conserve our way out of the problem unless we do far more, and change our behavior radically. Not very likely to happen.
Technology can also help us conserve energy. Sensors can detect if there is anyone in the room. Computers “spin down their disks” or dim the monitor to save energy. The image below is the Energy Conservation screen from my laptop computer (where I am writing this). For a laptop, the issue of conservation is very important (as it directly relates to battery life). Some of the new generation of computer chips for laptops will actually slow their clock speed when not connected to the mains to prolong mobility from the cord.
Here are some conservation tips that you can do:
That SUV is not very efficient. The model T ford managed 12 mpg, and a SUV might make 24 mpg, not a major improvement in over 100 years. Especially when other countries are driving vehicles which obtain 60 mpg. We are not going to stay home to drive less, (the average American car will drive 12,000 miles each year), so an efficient vehicle will result in a lot less CO2. The age of the vehicle has an impact as we are tending to get better (but slowly) at efficiencies. Fortunately, we have much greater success with the other pollutants through technologies such as the catalytic converter. For carbon dioxide emissions to be reduced from personal vehicles, efficiencies need to be improved.
This is all discussed in Unit I (appliances, lighting, etc.) and II (vehicles). If you do not recall the material, go and take a look at it again.
NOx consists of the following three gasses: NO, N2O, and NO2
Which one is also a greenhouse gas?
N2O is also known as laughing gas (used at the dentist during tooth pulling). But due to the very long lifetime in the atmosphere, where it is a greenhouse gas, we should limit how much we let into the atmosphere. Thus all the solutions to NOx removal (acid deposition), or mitigation, or prevention, are applicable to N2O reductions.
If having children is the problem then population growth restrictions might be the answer. Every child born in the US is going to want to have the same things:
All require energy! Some countries are currently promoting population growth restrictions, some are decreasing in size due to other reasons (AIDS being one of them). This will impact how easy or hard it is to reach the greenhouse gas reductions required.
The U.S. is growing. Every man, woman, and child will use energy, which produces carbon dioxide.
China and India are the countries to watch. While China is the most populous nation, India will overtake China in about 2015. Think about the impact on energy use when the Indians discover (can afford) air conditioning! Should we discourage their advances while maintaining our relatively lavish existence? The Kyoto Protocol uses the language "Every Country has the right to develop." Unfortunately, we can not afford to have these countries follow the same pathway with the same errors and the same environmental impact.
Technology transfer is a great idea but who should pay. Why should AB&B give away low NOx burners when they have investors expecting a return on investment? The emissions from the developing countries are what have kept the US out of active participation in Kyoto Protocol developments. Economic implications for the US without worldwide greenhouse gas reductions!
If we need a technology that provides electricity without greenhouse gas emissions, we already have one: Nuclear.
Recall the discussion on the nuclear future for the US? We have an aging nuclear reactor "fleet" and the predictions are that the percent of power generated from nuclear is going to decrease (for 2 reasons: as the economy and energy production grows the output of nuclear will remain about the same but the percent contribution will be less AND decommissioning of nuclear plants will result in a loss of capacity). The likely contender for filling the gaps in our energy supply: natural gas! Perhaps fear of climate change will overcome the fear of nuclear power? We have no significant plans to build new reactors currently so if this is going to play a role in CO2 emission growth reduction NOW is the time to act! The decommissioning of nuclear plants is increasing (Three Mile Island will close) as it is cheaper to use natural gas but that will increase CO2 emissions! There are some policy changes pending that may slow this down by valuing the electricity produced without CO2 emissions more.
If we don't expect nuclear to be an option (at least in the near future, for the US) then renewable energy may offer part of the solution. Recall that we only have significant electricity production from hydroelectric at this time but wind power is increasing its output at a rapid pace with perhaps a greater contribution for biomass (liquid fuels).
The cost of electricity is a key issue here. The renewable energies are more expensive! While wind has managed to reduce its cost dramatically, we are still waiting for solar cells and the other renewable technologies to become competitive. Of course, renewable energy enhances our national security, reduces air pollution (depending on what it is replacing as the energy generation source) and, of importance in this lesson, they produce no CO2!
These are some sites to gather additional information. A student who would like a better grade will go and spend some time thinking about what they have already learned and try to build on that foundation of knowledge. You do not need to all have exactly the same learning experience; spend some time on what interests you! It will help your grade and your ability to produce quality material. Information is power!
Climate Change (EPA) [248]
Hover over the text below for more details. After this complete the Lesson 12 quiz.
Accessible Version (word document) [250]
After looking at this map, please take the L12 quiz.
Success in this lesson will be based on the following things
Question: So are you glad the semester is over?
Click for answer.
Much of the course has looked back over the energy transitions. Let's spend a short lesson looking forward. Every year the department of energy (the energy information agency portion) releases the Annual Energy Outlook. These reports contain the latest energy statistics and projections. Take a look at this years Annual Energy Outlook Report [251] (read pages 5 to 10 to get an overview of the changes and emerging issues in Energy and Environment). Also of note is the BP report the BP Statistical Review of World Energy [252] See the one page overview on "2019 in a glance" (the 2020 report will be out in late 2021 with the Covid-19 impacts).
Related to the image of the world at night is the point sources of carbon dioxide emissions. Note that the locations are mostly in the developed nations with a strong presence from China and India.
The bulk of our energy-related pollution comes from electricity generation and transportation. For example look at the U.S. data.
Overall, we still expect to see carbon dioxide levels decreasing for the US in the short term. Hot summers (lots of air condensation), cold winters, and world economic productivity will influence emissions. Of issue is whether carbon dioxide sequestration will have a role to play in reducing the rate of growth of CO2 in the atmosphere in the future (perhaps). Fuel switching is the leading contributer to this reduction (shale gas replacing coal), but as we have seen, much of the international growth in electricity is likely to come from the cheapest, available source: coal.
Some nations have already enacted policies that have resulted in carbon dioxide emission reductions. Below is the artistic representation of the Sleipner natural gas platform in the North Sea off the coast of Norway. The rig is extracting natural gas, but like other natural gas wells, will also contain carbon dioxide. Separating and releasing the carbon dioxide is common, however, a carbon tax in Norway makes this expensive. Thus, they sequester the carbon dioxide in a deep saline aquifer under the ocean but above the gas field. With >10 years of experience >10 million toms of carbon dioxide have been stored. This is one of the few large-scale sequestration sites currently in operation. To put this in perspective: a 500 MW coal-fired power plant will generate nearly 4 million tons of CO2 per year.
There are a variety of large-scale point sources of carbon dioxide that could provide an opportunity for sequestration (or in the terminology of the day: carbon capture and storage). These could be electric utilities, cement manufacturing, refineries, ethanol production facilities, and others. If you would like more information on geologic sequestration see the Geologic Sequestration Atlas [253]. The image below shows large-scale point sources of carbon dioxide and the location of deep saline aquifers as well as oil and natural gas fields, and coal basins (some of the coal being too deep to mine and a potential sequestration site). Generally, we have good location citing between sources and sinks. Yet it is unclear how significant a role CCS will be in the future. It will not be enough by itself, to reduce carbon dioxide emissions back to previous levels.
For a look at how the U.S. might meet reduction goals (we are not sure what these reduction goals might be, and it will likely be a moving target):
Workers at Princeton suggested a 7 "wedges" strategy to meet 2004 carbon dioxide emission levels (it now seems that many nations will find the Kyoto reductions out of reach). "Very roughly, stabilization at 500 ppm requires that emissions be held near the present level of 7 billion tons of carbon per year (GtC/year) for the next 50 years, even though they are currently on course to more than double." There are 15 options, any 7 of which combined would provide the stabilization. View Introduction to the Wedges [254] from Princeton University for additional information.
Option 1: Improved fuel economy
Option 2: Reduced reliance on cars. A wedge would also be achieved if the average fuel economy of the 2 billion 2054 cars were 30 mpg, but the annual distance traveled were 5000 miles instead of 10,000 miles.
Option 3: More efficient buildings
Option 4: Improved power plant efficiency. This can be achieved through gasification of coal, oxy-combustion, and other approaches.
Option 5: Substituting natural gas for coalescent from natural gas has fewer CO2 emissions
Option 6: Storage of carbon captured in power plants
Option 7: Storage of carbon captured in hydrogen plants
Option 8: Storage of carbon captured in synfuels plants (carbon capture and storage)
Option 9: Nuclear fission
Option 10: Wind electricity
Option 11: Photovoltaic electricity
Option 12: Renewable hydrogen
Option 13: Biofuels
Option 14: Forest management
Option 15: Agricultural soils management. This is essentially terrestrial carbon capture, increased carbon in the soil.
None of these are easy fixes, each is a grand challenge alone. Together 7 of these will be a grand, grand challenge!
The full paper is: Pacala, S.; Socolow, R., Stabilization wedges: Solving the climate problem for the next 50 years with current technologies. Science 2004, 305 (5686), 968-972.
A word on the Kyoto Protocol. After Australia ratified the protocol in 2008, the U.S. stands alone as a participant who has signed but not ratified the Protocol. The Protocol became active in 2005 when the necessary number of participants (covering a certain percentage of the greenhouse gas emissions) had ratified it. How we move forward is not necessarily tied to the Kyoto Protocol. It will certainly be interesting to see how far we deal with CO2 and how quickly.
The map below shows the world's oil fields. But how much oil is left? The following link contains a table with proven worldwide reserves of oil and natural gas [255]. It’s interesting to see the total worldwide picture in one place and the number of countries that have proven hydrocarbon reserves. However, although it’s popular to measure reserves using the term “proven reserves,” that is not the whole story.
Proven reserves are not a measure of future supply. You have so far seen the simplified picture. Let's dig a little deeper into running out of oil: Look into this site by Bill Kovarik on the oil reserve fallacy. [256] Why is the situation more complex than the simple view? How much oil is there?
The images below show the locations of U.S. refineries and the natural gas pipeline network.
There are a number of observations that can be made from these figures. Firstly, there are concentrations of refineries in the Texas/Louisiana Gulf Coast. There is significant production in those areas and also oil can be offloaded at the major oil ports. The Northeast U.S. has refineries clustered in the coastal areas, again access to both domestic and imported oil. There is obviously a demand for refined products in densely populated areas.
For the natural gas pipelines, there are a number of locations where natural gas can be imported to or exported from the US. This includes 9 LNG (liquefied natural gas) facilities in the continental US and Alaska and an additional one in Puerto Rico. LNG is important to the US in that it allows natural gas to be transported by special ships after converting the gas to a liquid (by lowering the temperature of the gas to minus 160 °C. Prior to the acceptance of this process by the industry, gas was vented to the atmosphere or burned in many places in the world as it was not economical to transport it by pipeline. There are many sources available on the internet if you would like more information on LNG. An overview is here [257]. Bottom line is that natural gas is a desirable fuel that is mostly stranded as we do not yet have the pipelines to export large quantities overseas through LNG shipping terminals.
You can see from the charts below that not all producing countries have significant refining capacities. Countries that have significant oil production such as Nigeria, export crude to other countries and import refined products such as gasoline.
Every year the demand for electricity grows. Traditionally, the bulk of the demand has come from the OECD countries, which include the developed nations. However, there is rapid growth in the "developing countries." Of particular note is the growth associated with China and India.
Given the abundance of coal in many of the developed and developing countries, it seems likely that coal will play an increasingly important role in electricity production. This has implications for carbon dioxide emissions and other pollutants, as much of the new capacity in developing nations have limited pollution controls.
Yet with all this growth there are still other considerations for those who will still not have access to electricity. Also, recent reports have questioned if we have access to the coal we think we have. The economics of extraction and the legal access is impacted by graveyards, roadways, etc. An analysis of the Powder River Basin coal field reduced the reserve base by 50%. When we look closer, this may be the case with other fields too. So a 250 year supply is likely on the high side. Perhaps 100 years or so is more likely. We will see.
Yet with all this growth there are still other considerations for those who will still not have access to electricity. Currently in the millions, most of the world is expected to have an increase in electrification and a reduction of those without access to electricity. However, sub-Saharan Africa will increase those without access.
You get a striking view of this inequity (and population clustering) when viewing this well known composite image of the Earth viewed from space at night.
This is the end of the course material. Please complete the Lesson 13 quiz.
Links
[1] https://stock.adobe.com/208537836?as_campaign=TinEye&as_content=tineye_match&epi1=208537836&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[2] https://stock.adobe.com/contributor/205307279/alexlmx?load_type=author&prev_url=detail
[3] https://stock.adobe.com/287860402?as_campaign=TinEye&as_content=tineye_match&epi1=287860402&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[4] https://stock.adobe.com/contributor/293582/new-africa?load_type=author&prev_url=detail
[5] https://creativecommons.org/licenses/by-nc-sa/4.0/
[6] https://www.youtube.com/channel/UCa_viCpI7UoNkZRzgEtE9sQ
[7] https://www.epa.gov/ozone-layer-protection
[8] https://www.youtube.com/channel/UC7EGgnYFEIOaAa47ZBpninw
[9] https://www1.eere.energy.gov/buildings/ssl/sslbasics_ledbasics.html
[10] https://www.eia.gov/energyexplained/units-and-calculators/degree-days.php
[11] https://stock.adobe.com/contributor/23608/robert-pernell?load_type=author&prev_url=detail
[12] http://stock.adobe.com/search/images?k=house+wrap&search_type=default-asset-click&asset_id=376257
[13] https://stock.adobe.com/contributor/4654/syda-productions?load_type=author&prev_url=detail
[14] https://stock.adobe.com/116179077?as_campaign=TinEye&as_content=tineye_match&epi1=116179077&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[15] https://archive.epa.gov/climatechange/kids/solutions/technologies/geothermal.html
[16] https://energy.gov/energysaver/geothermal-heat-pumps
[17] https://stock.adobe.com/contributor/10785/ursula-page?load_type=author&prev_url=detail
[18] https://stock.adobe.com/209223700?as_campaign=TinEye&as_content=tineye_match&epi1=209223700&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[19] https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html
[20] https://stock.adobe.com/contributor/206863694/kamil-k2p?load_type=author&prev_url=detail
[21] https://stock.adobe.com/204076949?as_campaign=TinEye&as_content=tineye_match&epi1=204076949&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[22] https://stock.adobe.com/contributor/201213509/mmphoto?load_type=author&prev_url=detail
[23] https://stock.adobe.com/314129690?as_campaign=TinEye&as_content=tineye_match&epi1=314129690&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[24] https://stock.adobe.com/contributor/301569/maksym-yemelyanov?load_type=author&prev_url=detail
[25] https://stock.adobe.com/115205032?as_campaign=TinEye&as_content=tineye_match&epi1=115205032&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[26] https://www.e-education.psu.edu/egee101/sites/dev.e-education.psu.edu.egee101/files/Lesson01/L01_elec_choice.mp3
[27] https://stock.adobe.com/contributor/202840310/pdm?load_type=author&prev_url=detail
[28] https://stock.adobe.com/289851476?as_campaign=TinEye&as_content=tineye_match&epi1=289851476&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[29] https://stock.adobe.com/113571235?as_campaign=TinEye&as_content=tineye_match&epi1=113571235&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[30] https://stock.adobe.com/contributor/205109741/myimagination?load_type=author&prev_url=detail
[31] https://stock.adobe.com/images/wooden-electrical-post/80241801
[32] https://stock.adobe.com/contributor/200935510/pellinni?load_type=author&prev_url=detail
[33] https://stock.adobe.com/images/high-voltage-power-lines-tower-in-carpathian-mountains-lovely-green-energy-industry-concept-beautiful-landscape-in-autumn-with-blue-sky-and-some-clouds/214236482
[34] https://stock.adobe.com/contributor/202371514/jakit17?load_type=author&prev_url=detail
[35] https://stock.adobe.com/209809392?as_campaign=TinEye&as_content=tineye_match&epi1=209809392&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[36] https://www.e-education.psu.edu/egee101/sites/dev.e-education.psu.edu.egee101/files/Lesson01/Lesson%201%20Coverage%20Map.docx
[37] http://www.marcellus.psu.edu/
[38] https://www.youtube.com/channel/UCUNcvG7nwi7blC7AslmBRwA
[39] https://www.ge.com/power/resources/knowledge-base/what-is-a-gas-turbine#c3916284c4e44623b72230b270cbb357
[40] https://en.wikipedia.org/wiki/Kelvin
[41] https://stock.adobe.com/contributor/200488604/driftwood?load_type=author&prev_url=detail
[42] https://stock.adobe.com/images/power-plant/33352727?prev_url=detail
[43] https://www.tva.com/energy/our-power-system/coal/how-a-coal-plant-works#:~:text=Coal%2Dfired%20plants%20produce%20electricity,to%20start%20the%20process%20over.
[44] https://stock.adobe.com/contributor/204517492/alexrow?load_type=author&prev_url=detail
[45] https://stock.adobe.com/images/disassembled-steam-turbine-in-the-process-of-generator-repair-at-power-plant/212224245?prev_url=detail
[46] https://www.youtube.com/channel/UCEik-U3T6u6JA0XiHLbNbOw
[47] https://en.wikipedia.org/wiki/Chernobyl_disaster
[48] https://en.wikipedia.org/wiki/Three_Mile_Island_accident
[49] https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster
[50] https://www.nei.org/news/2019/what-happens-nuclear-waste-us
[51] https://en.wikipedia.org/wiki/Yucca_Mountain_nuclear_waste_repository
[52] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson02/Lesson%202%20and%203%20Coverage%20Map.docx
[53] https://stock.adobe.com/contributor/205494801/mike-fouque?load_type=author&prev_url=detail
[54] https://stock.adobe.com/346458341?as_campaign=TinEye&as_content=tineye_match&epi1=346458341&tduid=162c3721f33a81b2992acf0c8bd83f41&as_channel=affiliate&as_campclass=redirect&as_source=arvato
[55] https://stock.adobe.com/contributor/206691374/%EC%88%98%EB%8F%99-%EA%B9%80?load_type=author&prev_url=detail
[56] https://stock.adobe.com/images/water-wheel-in-korea/222319660
[57] https://en.wikipedia.org/wiki/Three_Gorges_Dam
[58] https://energy.gov/eere/water/how-hydropower-works
[59] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson02/L02_pumped_storage.mp3
[60] https://www.e-education.psu.edu/egee101/node/823
[61] http://www.oceanenergycouncil.com/
[62] https://www.youtube.com/c/Acciona_Corp/about
[63] http://energy.gov/eere/renewables/wind
[64] https://stock.adobe.com/contributor/201003291/kruwt?load_type=author&prev_url=detail
[65] https://stock.adobe.com/images/offshore-farm-windturbines-near-dutch-coast/143721774?prev_url=detail
[66] https://www.energy.gov/eere/solar/solar-photovoltaic-technology-basics
[67] https://stock.adobe.com/contributor/200994435/vladimir-gerasimov?load_type=author&prev_url=detail
[68] https://stock.adobe.com/images/aerial-top-view-of-a-solar-pannels-power-plant/284063002?prev_url=detail
[69] https://www.energy.gov/eere/solar/concentrating-solar-thermal-power
[70] https://www.energy.gov/eere/geothermal/geothermal-basics
[71] https://www.energy.gov/eere/geothermal/hydrothermal-resources
[72] https://www.energy.gov/eere/articles/5-things-know-about-geothermal-power
[73] https://www.youtube.com/channel/UCbVKIQMvSWEDLnQIAWE9IgA
[74] https://www.eia.gov/energyexplained/hydropower/tidal-power.php
[75] https://www.youtube.com/channel/UCr2F-Kyi8vFXlRgEUozAD5w
[76] https://www.eia.gov/energyexplained/hydropower/wave-power.php
[77] https://www.eia.gov/electricity/monthly/
[78] https://www.eia.gov/totalenergy/data/monthly/previous.php
[79] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/origins_of_coal.pdf
[80] https://stock.adobe.com/contributor/200441122/aelita?load_type=author&prev_url=detail
[81] https://stock.adobe.com/images/green-leaf-against-the-blue-sky/33222789
[82] https://www.eia.gov/todayinenergy/detail.php?id=4390
[83] http://www.epa.gov/airmarkets/progsregs/arp/index.html
[84] https://stock.adobe.com/contributor/50238/stef?load_type=author&prev_url=detail
[85] https://stock.adobe.com/images/charbon/31428900
[86] https://stock.adobe.com/contributor/83934/renate-promitzer?load_type=author&prev_url=detail
[87] https://stock.adobe.com/images/koks/7540452
[88] http://umwa.org/about/who-we-represent/mining-industry/
[89] https://stock.adobe.com/contributor/203501742/blueringmedia?load_type=author&prev_url=detail
[90] https://stock.adobe.com/images/underground-landscape-of-coal-mine/377252741
[91] https://stock.adobe.com/contributor/205900573/borodatch?load_type=author&prev_url=detail
[92] https://stock.adobe.com/images/coal-mining-industry-and-transportation-set-infographics-elements-isolated-vector-technics-buildings/134592860
[93] https://www.youtube.com/channel/UCjYrT--TpOrA86Iw_PkoVJw
[94] https://stock.adobe.com/contributor/207554633/sunshine-seeds?load_type=author&prev_url=detail
[95] https://stock.adobe.com/images/coal-ore-on-a-conveyor-belt-for-processing/331385933
[96] https://stock.adobe.com/contributor/201635100/dule964?load_type=author&prev_url=detail
[97] https://stock.adobe.com/images/black-powder-coal-dust-isolated-on-white-background/141399101
[98] http://umwa.org/news-media/journal/black-lung-resurgence/
[99] https://stock.adobe.com/contributor/203116606/nordroden?load_type=author&prev_url=detail
[100] https://stock.adobe.com/images/a-large-quarry-with-many-horizons-and-ledges-vertical-bedding-of-coal-seams/302720178
[101] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/abandoned_coal_mine_APP.gif
[102] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/L03_reclaimed_land_OSME.gif
[103] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/surface_coal_mine1.gif
[104] https://stock.adobe.com/contributor/205336102/whitcomberd?load_type=author&prev_url=detail
[105] https://stock.adobe.com/images/aerial-drone-view-of-a-huge-opencast-coal-mine-cut-into-a-rural-hilly-area-dowlais-merthyr-tydfil-wales/215007863
[106] https://www.youtube.com/channel/UC0k173Oca1nPZurW2ITHlYw
[107] https://www.e-education.psu.edu/egee101/node/672
[108] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/amd1_USGS.gif
[109] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/amd2_USGS.gif
[110] https://stock.adobe.com/contributor/205198230/shootdiem?load_type=author&prev_url=detail
[111] https://stock.adobe.com/images/fantastic-view-of-open-pit-mining-on-cloudy-sky/299510614
[112] https://www.minemaps.psu.edu
[113] https://stock.adobe.com/contributor/205439036/wn8540284?load_type=author&prev_url=detail
[114] https://stock.adobe.com/images/opencast-mine-belt-conveyor-coal-stones-transport/339842530
[115] https://stock.adobe.com/contributor/203029387/timofeev?load_type=author&prev_url=detail
[116] https://stock.adobe.com/images/large-quarry-dump-truck-loading-the-rock-in-dumper-loading-coal-into-body-truck-production-useful-minerals-mining-truck-mining-machinery-to-transport-coal-from-open-pit-as-the-coal-production/251271397
[117] https://stock.adobe.com/contributor/205971776/agnormark?load_type=author&prev_url=detail
[118] https://stock.adobe.com/images/train-coal-mining-export-shipment/277651289
[119] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson03/L03_titanic.mp3
[120] https://stock.adobe.com/contributor/38750/tupungato?load_type=author&prev_url=detail
[121] https://stock.adobe.com/images/coal-transportation/210846570
[122] https://stock.adobe.com/contributor/206833199/parilov?load_type=author&prev_url=detail
[123] https://stock.adobe.com/images/loading-coal-mining-in-port-on-cargo-tanker-ship-with-crane-bucket-of-train-aerial-top-view/277788506
[124] https://stock.adobe.com/contributor/207577263/marko-hannula?load_type=author&prev_url=detail
[125] https://stock.adobe.com/images/a-large-pile-of-coal-stored-near-a-power-plant-located-next-to-the-waterfront/382687470
[126] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/Lesson%204%20Coverage%20map.docx
[127] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/747_Jet_Takeoff.aif
[128] https://courseware.e-education.psu.edu/courses/egee101/transcript/lesson_4_air_plane_take_off.html
[129] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/L04_aircraft_brakes.mp3
[130] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/Text_Airplane%20cargo.html
[131] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/L04_salt.mp3
[132] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/fruit_jpm.gif
[133] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/bear_beer_jpm.gif
[134] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/nuc_sub_NSF.gif
[135] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/Choo_Choo_Train.aif
[136] https://courseware.e-education.psu.edu/courses/egee101/transcript/lesson_3_steam_train.html
[137] https://www.epa.gov/air-trends#comparison
[138] https://obamawhitehouse.archives.gov/the-press-office/2012/08/28/obama-administration-finalizes-historic-545-mpg-fuel-efficiency-standard
[139] http://www.fueleconomy.gov/feg/drive.shtml
[140] http://www.howstuffworks.com/horsepower1.htm
[141] http://www.howstuffworks.com/engine.htm
[142] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/L04_lead.mp3
[143] http://www.fueleconomy.gov/feg/why.shtml
[144] http://www.fhwa.dot.gov/policyinformation/statistics/2009/in4.cfm
[145] http://www.smartusa.com/
[146] https://www.energy.gov/eere/electricvehicles/electric-vehicle-basics
[147] https://www.energy.gov/eere/electricvehicles/electric-vehicle-benefits
[148] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/search4unleaded.mp3
[149] http://youtu.be/zz9naP83ndU
[150] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/L04_marmite.mp3
[151] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/Just%20Like%20Marmite_Text.html
[152] https://www.e-education.psu.edu/egee101/node/762
[153] https://www.e-education.psu.edu/egee101/node/760
[154] https://www.e-education.psu.edu/egee101/node/761
[155] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson04/L04_ethanol_Brazil.mp3
[156] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/Lesson%205%20Coverage%20Map.docx
[157] http://youtu.be/i3ctRVPVTC4
[158] https://courseware.e-education.psu.edu/courses/egee101/flash/ternary.html
[159] https://www.nrdc.org/stories/what-keystone-pipeline
[160] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/L05_pipelineLeak.mp3
[161] http://www.bp.com/en/global/corporate/gulf-of-mexico-restoration/deepwater-horizon-accident-and-response.html
[162] http://beyondeconomics.org/2010/07/05/gulf-oil-spill/
[163] https://www.e-education.psu.edu/egee101/node/767
[164] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/desired_products.mp3
[165] http://science.howstuffworks.com/environmental/energy/oil-refining.htm
[166] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson05/lead.mp3
[167] http://www.adventuresinenergy.org/Refining-Oil/index.html
[168] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson06/Lesson%206%20Coverage%20Map.docx
[169] https://www.e-education.psu.edu/egee101/node/790
[170] https://oceanservice.noaa.gov/facts/phyto.html
[171] http://walrus.wr.usgs.gov/seeps/what.html
[172] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/oil_overview.pdf
[173] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson06/L06_not_worried.mp3
[174] http://www.chk.com/Media/Educational-Library/Animations/Pages/Completion-Animation.aspx
[175] https://www.canadasoilsands.ca/en/what-are-the-oil-sands/recovering-the-oil
[176] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson06/L06_Ottowa.mp3
[177] https://www.nationalgeographic.org/encyclopedia/petroleum/
[178] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson07/Lesson%207%20Coverage%20Map.docx
[179] http://en.wikipedia.org/wiki/Russia%E2%80%93Ukraine_gas_disputes
[180] http://www.usesc.org/energy_security/energysecurity
[181] https://www.eia.gov/energyexplained/oil-and-petroleum-products/use-of-oil.php
[182] https://www.investopedia.com/articles/investing/032515/how-oil-prices-impact-us-economy.asp
[183] https://www.e-education.psu.edu/egee101/node/752
[184] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson07/oil_prices_2012.gif
[185] https://youtu.be/p6LXT3-P7QY
[186] http://www.iea.org/
[187] http://energy.gov/fe/services/petroleum-reserves
[188] https://obamawhitehouse.archives.gov/energy/securing-american-energy
[189] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/blueprint_secure_energy_future_Oil_WhiteHouse.pdf
[190] http://georgewbush-whitehouse.archives.gov/infocus/energy/
[191] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson08/Lesson%208%20Coverage%20Map.docx
[192] https://www.mrgscience.com/ess-topic-63-photochemical-smog.html
[193] https://creativecommons.org/licenses/by-sa/4.0/
[194] https://www.youtube.com/channel/UCAY-SMFNfynqz1bdoaV8BeQ?pbjreload=102
[195] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson08/L08_smog_EPA.pdf
[196] https://stock.adobe.com/images/los-angeles-skyline-with-smog-and-smoke/334253951
[197] https://stock.adobe.com/images/cotopaxi-volcano-eruption/92030899?prev_url=detail
[198] https://stock.adobe.com/images/pollution-from-the-exhaust-of-cars-in-the-city-in-the-winter-smoke-from-cars-on-a-cold-winter-day/247258123
[199] https://stock.adobe.com/images/closeup-of-cigarette-on-ashtray-with-a-beautiful-wisp-of-smoke/271850288
[200] https://epa.maps.arcgis.com/apps/Cascade/index.html?appid=e4dbe2263e1f49fb849af1c73a04e2f2
[201] https://www.youtube.com/channel/UCHXdDvAkuK5BjhrYHY4hOzQ
[202] https://www.youtube.com/channel/UC4e6MKRiaG47SfHGjtUejyQ
[203] https://www.explainthatstuff.com/electrostaticsmokeprecipitators.html
[204] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson09/Lesson%209%20Coverage%20Map.docx
[205] http://volcanoes.usgs.gov/hazards/gas/index.php
[206] https://www.usgs.gov/media/images/usgs-hvo-geochemist-measuring-gases-released-k-lauea-volcano
[207] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson09/L09_Teidi.mp3
[208] https://www.epa.gov/mercury
[209] https://www.nps.gov/media/photo/gallery.htm?pg=3312826&id=609C1A91-F3AE-4FA7-886C-A4DD1A76FA54
[210] https://www.epa.gov/air-trends/air-quality-national-summary#air-quality-trends
[211] https://www.epa.gov/airmarkets
[212] https://www.epa.gov/acidrain/acid-rain-program-results
[213] https://www.eia.gov/todayinenergy/detail.php?id=44536
[214] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson09/fleet_emissions_EPA_LD.html
[215] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/Lesson%2010%20Coverage%20Map.docx
[216] https://www.e-education.psu.edu/egee101/node/766
[217] https://courseware.e-education.psu.edu/courses/egee101/L10_climate/plants.html
[218] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/photosyntheis.mov
[219] https://www.e-education.psu.edu/egee101/node/805
[220] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/greenhouse.gif
[221] https://courseware.e-education.psu.edu/courses/egee101/images/L10/emschart_NASA.gif
[222] https://science.nasa.gov/ems/01_intro
[223] http://imagers.gsfc.nasa.gov/ems/waves.html
[224] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/L10_CH4.mov
[225] https://courseware.e-education.psu.edu/courses/egee101/L10_climate/temps.html
[226] https://www.koshland-science-museum.org/explore-the-science/interactives/what-is-the-greenhouse-effect#
[227] http://www.bloomberg.com/graphics/2015-whats-warming-the-world/
[228] http://hvo.wr.usgs.gov/maunaloa/
[229] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/L10_wood_lake.mp3
[230] http://www.pbs.org/wgbh/warming/etc/graphs.html
[231] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/L10_land_change.mp3
[232] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/plant_life.aif
[233] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/L10_water_world.mp3
[234] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/earth_night_NASA.jpg
[235] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/USA2.gif
[236] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/l10_119_why_hap.mov
[237] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/impact_ice_snow.mov
[238] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/predictions.mov
[239] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson11/Lesson%2011%20Coverage%20Map.docx
[240] http://unfccc.int/2860.php
[241] http://www.businessinsider.com/what-did-us-agree-to-paris-climate-deal-2017-5
[242] https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement
[243] https://www.epa.gov/emissions-trading-resources/how-do-emissions-trading-programs-work
[244] http://www.mbari.org/ghgases/deep/release.htm#frame
[245] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson10/L10_CO2_sequest1_MBARI.mpg
[246] http://knowledgecenter.csg.org/kc/content/carbon-capture-and-storage
[247] https://www.census.gov/popclock/
[248] http://www.epa.gov/climatechange/index.html
[249] http://www.pbs.org/wgbh/warming/index.html
[250] https://www.e-education.psu.edu/egee101/sites/www.e-education.psu.edu.egee101/files/Lesson12/Lesson%2012%20Coverage%20Map.docx
[251] https://www.eia.gov/outlooks/aeo/pdf/AEO_Narrative_2021.pdf
[252] https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2020-full-report.pdf
[253] https://www.netl.doe.gov/research/coal/carbon-storage/natcarb-atlas
[254] http://cmi.princeton.edu/wedges/intro
[255] http://www.eia.gov/countries/
[256] http://environmentalhistory.org/2014/06/19/oil-industry/
[257] http://www.giignl.org/about-lng/lng-basics
[258] http://www.eia.doe.gov