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

Table VIII.A.3-1
Well-to-Pump Emissions for Producing and Distributing Renewable Fuels
(grams per gallon ethanol or biodiesel) a
Pollutant Ethanol Biodiesel
VOC 3.6 41.5
CO 4.4 25.1
NOx 10.8 44.3
PM10 6.1 1.5
SOx 7.2 7.5
a Includes credit for reduced distribution of gasoline and
diesel fuel
At the same time, areas with refineries might experience reduced emissions, not
necessarily relative to current emission levels, but relative to those which would have
occurred in the future had renewable fuel use not risen. However, to the degree that
increased renewable fuel use reduces imports of gasoline and diesel fuel, as opposed to
the domestic production of these fuels, these reduced refinery emissions will occur
overseas and not in the U.S.
Similarly, areas with MTBE production facilities might experience reduced
emissions from these plants as they cease producing MTBE. However, many of these
plants may be converted to produce other gasoline blendstocks, such as iso-octane or
alkylate. In this case, their emissions are not likely to change substantially.
B. Impact on Emission Inventories
We use the NMIM to estimate emissions under the various ethanol scenarios on a
county by county basis. NMIM basically runs MOBILE6.2 and NONROAD2005 with
county-specific inputs pertaining to fuel quality, ambient conditions, levels of onroad
vehicle VMT and nonroad equipment usage, etc. We ran NMIM for two months, July
and January. We estimate annual emission inventories by summing the two monthly
inventories and multiplying by six.
As described above, we removed the effect of gasoline fuel quality on exhaust
VOC and NOx emissions from the onroad motor vehicle inventories which are embedded
in MOBILE6.2. We then applied the exhaust emission effects from the EPA Predictive
Models. In our primary analysis, we only applied these EPA Predictive Model effects to
exhaust VOC and NOx emissions from Tier 0 vehicles. In a sensitivity case, we applied
them to exhaust VOC and NOx emissions from all vehicles. Regarding the effect of fuel
quality on emissions of four air toxics from nonroad equipment (in terms of their fraction
of VOC emissions), in all cases we replaced the fuel effects contained in NMIM with
those for motor vehicles contained in MOBILE6.2. The projected emission inventories
for the primary analysis are presented first, followed by those for the sensitivity analysis.
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