EGEE 101
Energy and the Environment

Pollution Issues and Reduction Strategies

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Back of a car and the contents of exhaust (carbon dioxie, N O x, unburned hydrocarbons, and carbon monoxide).
The exhaust of my now long gone Corolla is spewing out the gases (engine has just started) that are of environmental concern.
Credit: JPM

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).

Conservation

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:

  • Combine trips, go to the supermarket on the way home from work.
  • Carpool (although this might be an efficiency increase rather than a conservation).
  • Can you think of some additional examples?

Efficiency

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.

Between 40 and 70 mph is the sweep spot for higher mpg but it is vehicle dependent.
I am with Sammy on this: "I can't drive 55!" The mpg is dependent on the speed of the vehicle for our automobiles. This is why 55 MPH (was introduced IN THE 1970's think about what happened in 1974 with our crude oil supply). I have had several speeding tickets, the first one was for overtaking a policeman (now that was a dumbass move!) Authors note: was very disappointed when the police followed me over the County line (the Dukes of Hazzard led me astray).
A busy highway with dense traffic.
We are not very efficient in stop and go traffic. The kinetic energy goes to zero when stationary. Normally highway driving is more efficient (higher mpg) but not during the rush "hour(s)" when many of the major arteries are gridlocked. Routing traffic around traffic problems is a technological approach that would save fuel and more importantly cut down on sitting in traffic (this is why I live in State College).
Credit: Ibl
Graphic showing that a large amount of hydrocarbon pollution comes from relatively few cars (35% from 1% of cars).
Vehicles have become much cleaner than they were. However, the older vehicles on the road contribute to much of the pollution. The newer vehicles are cleaner now because of a combination of cleaner vehicles and cleaner fuels. Things are getting better now as many of these vehicles are now off the road (and in the scrap heap).
Credit: EPA & MW
Line graph showing the fuel efficiency of light-duty vehicles, cars versus trucks. Cars have highest MPG followed by vans, then SUVs, and then pick ups.
We have not experienced a dramatic increase in efficiency of the use of liquid fuels in the 1990's to 2005 but did improve in the 1970's (there is a good reason for this especially after 1974-what is it?) You might even expect the efficiency of cars to have decreased because of the popularity of SUV's in the 1990's. The reason it didn't: SUV's were considered to be light trucks but that has changed (more on this in Lesson 08). Government regulation is what has the largest impact on efficiency increases. Climate change and energy security are now impacting the MPG with higher standards expected. Vehicles cost more but cost of fuel is less, over the lifetime of the vehicle we expect savings. Soon 35.5 mpg (2017) is the goal with 54.5 mpg by 2025! However, there were roll-backs on the efficiency standards under the Trump administration and a fight to take away the special power of California to regulate emissions beyond the Federal government (due to the higher pollution levels there). Biden will need to reduce transport emissions to meet climate change goals.
Bar graph showing the number of vehicles per thousand persons (the United States is the highest with 800 followed by Canada at 700).
We have more vehicles (per 1000 persons) than other nations.
Credit: IEA, updated statistics here (see the growth in China!)

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.

a European road
You won't see many SUV's on these roads....
Credit: Ann Taylor, e-Ed Institute

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:

  • Increase efficiencies (it is more important when the fuel is much more expensive — due to taxation)
  • Cheaper vehicles (again taxation is much higher and the cost of vehicles are thus more expensive, smaller or alternative fuel vehicles alsopay a cheaper road tax etc.)
  • The ability to park the car on the congested streets where limited parking is typical
Phootgraph of a very small electric smart car.
Smart cars (this one is electric)
Credit: Smart Car U.S.

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 (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.

Electric Vehicles

Have a look at these two pages from the Office of Energy Efficiency and Renewable Energy.