The Energy Information Administration reports that US carbon emissions in 2006 w

Question

The Energy Information Administration reports that US carbon emissions in 2006 were 1,617 million metric tones per year (Mt C/yr). The DOE also reported the following carbon dioxide data (in MtCO2/yr) for the electric sector that year:

What % of the total carbon emissions for the year could be eliminated if coal were replaced with natural gas? (Assume no change in efficiency.)

If coal were replaced with a combination of solar, wind and nuclear power?

Explanation / Answer

Ans:

For the same energy released, natural gas emits around 55% and oil emits around 75% of
the CO2 as coal.Natural gas is the cleanest burning of the fossil fuels with respect to carbon dioxide. Hydrocarbons with more hydrogen atoms than carbon atoms release a larger fraction of theirenergy during combustion through water formation rather than CO2 formation. Thus hydrocarbons with higher ratios of hydrogen atoms to carbon atoms emit less CO2 per unit of energy produced than those with lower ratios. Molecules of methane, the primary component of natural gas, have four hydrogen atoms for every carbon atom, the highest possible ratio for a hydrocarbon. Larger hydrocarbons like oil and coal have fewer hydrogen atoms per carbon atom and thus emit more CO2 per unit of energy produced. Hence around 55% of the carbon emissions can be reduced if coal is replaced by natural gas.

If coal is being replaced by a combination of wind,nuclear power very high percentage of carbon emission can be avoided, as these energy producing methods do not emit carbon.

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