EGEE 101
Energy and the Environment

Where are the Greenhouse Gasses Coming From?

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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?)

U.S. Carbon Emission Sources. Carbon emissions are from the energy intensive operations, mostly electric utilities and transportation, contributing 56% of the emissions.
Credit: EPA
 Carbon Dioxide Emissions (kilograms per millionBtu) Natural Gas 57, Oil 79, Coal 89
Carbon Dioxide Emissions (kilograms per million Btu of fuel). For the same amount of fuel energy, coal will release more CO2. Why are they not all the same?
Credit: NETL Combustion Calculations - HHV basis

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. (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.