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

assumed to be affected by ethanol. Emissions of the four air toxics generally decrease
slightly, due to the greater reduction in exhaust VOC emissions.
3. Local and Regional VOC and NOx Emission Impacts In July
We also estimate the percentage change in VOC and NOx emissions from
gasoline fueled motor vehicles and equipment in those areas which actually experienced a
significant change in ethanol use. Specifically, we focused on areas where the market
share of ethanol blends was projected to change by 50 percent or more. We also focused
on summertime emissions, as these are most relevant to ozone formation. Finally, we
developed separately estimates for: 1) RFG areas, including the state of California and
the portions of Arizona where their CBG fuel programs apply, 2) low RVP areas (i.e.,
RVP standards less than 9.0 RVP, and 3) areas with a 9.0 RVP standard. This set of
groupings helps to highlight the emissions impact of increased ethanol use in those areas
where emission control is most important.
Table VIII.B.3-1 presents our primary estimates of the percentage change in VOC
and NOx emission inventories for these three types of areas. While ethanol use is going
up in the vast majority of the nation, ethanol use in RFG areas under the “Minimum Use
in RFG” scenarios is actually decreasing compared to the 2012 reference case. This is
important to note in order to understand the changes in emissions indicated.
Table VIII.B.3-1
Change in Emissions from Gasoline Vehicles and Equipment in Counties Where Ethanol
Use Changed Significantly – Primary Analysis
Ethanol Use 7.2 Billion Gallons 9.6 Billion Gallons
Ethanol Use in RFG Minimum Maximum Minimum Maximum
RFG Areas
Ethanol Use Down Up Down Up
VOC 1.6% 0.4% 1.6% 0.4%
NOx -5.2% 2.4% -5.2% 2.4%
Low RVP Areas
Ethanol Use Up Up Up Up
VOC 3.1% 3.2% 4.1% 3.5%
NOx 4.1% 6.0% 4.8% 4.4%
Other Areas
Ethanol Use Up Up Up Up
VOC 4.1% 4.1% 5.4% 4.4%
NOx 4.6% 6.0% 5.8% 4.8%
As expected, increased ethanol use tends to increase NOx emissions. The
increase in low RVP and other areas is greater than in RFG areas, since the RFG in the
RFG areas included in this analysis all contained MTBE. Also, increased ethanol use
tends to increase VOC emissions, indicating that the increase in non-exhaust VOC
emissions exceeds the reduction in exhaust VOC emissions. This effect is muted with
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