Regulation of Fuels and Fuel Additives: Renewable Fuel Standard ...

Table IX.C.1-1
Fossil fuel impacts of increased use of renewable fuels in the
transportation sector in 2012, relative to the 2012 reference case
RFS Required Projected Volume:
volume: 7.5 Bgal 9.9 Bgal
Reduction (quadrillion Btu) 0.2 0.3
Percent reduction 0.5 % 0.8 %
Table IX.C.1-2
Petroleum impacts of increased use of renewable fuels in the
transportation sector in 2012, relative to the 2012 reference case
RFS Required Projected Volume:
volume: 7.5 Bgal 9.9 Bgal
Reduction (billion gal) 2.3 3.9
Percent reduction 1.0 % 1.6 %
2. Greenhouse Gases And Carbon Dioxide
One issue that has come to the forefront in the assessment of the environmental
impacts of transportation fuels relates to the effect that the use of such fuels could have
on emissions of greenhouse gases (GHGs). The combustion of fossil fuels has been
identified as a major contributor to the increase in concentrations of atmospheric carbon
dioxide (CO2) since the beginning of the industrialized era, as well as the build-up of
trace GHGs such as methane (CH4) and nitrous oxide (N2O). This lifecycle analysis
evaluates the impacts of renewable fuel use on greenhouse gas emissions.
The relative global warming contribution of emissions of various greenhouse
gases is dependant on their radiative forcing, atmospheric lifetime, and other
considerations. For example, on a mass basis, the radiative forcing of CH4 is much
higher than that of CO2, but its effective atmospheric residence time is much lower. The
relative warming impacts of various greenhouse gases, taking into account factors such as
atmospheric lifetime and direct warming effects, are reported on a ‘CO2-equivalent’ basis
as global warming potentials (GWPs). The GWPs used by GREET were developed by
the UN Intergovernmental Panel on Climate Change (IPCC) as listed in their Third
Assessment Report 95 , and are shown in Table IX.C.2-1.
95 IPCC “Climate Change 2001: The Scientific Basis”, Chapter 6; Intergovernmental Panel on Climate
Change; J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, C.A. Johnson, and
K. Maskell, eds.; Cambridge University Press. Cambridge, U.K. 2001.
http://www.grida.no/climate/ipcc_tar/wg1/index.htm
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