Regulation of Fuels and Fuel Additives: Renewable Fuel Standard ...
Regulation of Fuels and Fuel Additives: Renewable Fuel Standard ...
Regulation of Fuels and Fuel Additives: Renewable Fuel Standard ...
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Table VIII.A.1.b-1<br />
Effect <strong>of</strong> RFG on Per Mile Emissions from Tier 0 Vehicles<br />
Relative to a Typical 9psi RVP Conventional Gasoline a<br />
Pollutant Source Non-Oxy<br />
RFG<br />
11 Volume<br />
Percent MTBE<br />
10 Volume<br />
Percent Ethanol<br />
VOC EPA Predictive<br />
Exhaust Emissions<br />
-7.7% -11.1% -12.9%<br />
NOx<br />
Models -1.7% 2.4% 6.3%<br />
CO MOBILE6.2 -24% -28% -32%<br />
Exhaust EPA Predictive -18% -30% -35%<br />
Benzene <strong>and</strong> Complex<br />
Formaldehyde Models<br />
7% 11% 2%<br />
Acetaldehyde 7% -8% 143%<br />
1,3-Butadiene<br />
22% 2% -7%<br />
Non-Exhaust Emissions<br />
VOC MOBILE6.2 &<br />
CRC E-65<br />
-30% -30% -18%<br />
Benzene MOBILE6.2 &<br />
Complex Models<br />
-5% -15% -7%<br />
a<br />
Average per vehicle effects for the 2012 fleet during summer conditions<br />
As can be seen, the oxygenated RFG blends are predicted to produce a greater reduction<br />
in exhaust VOC <strong>and</strong> CO emissions than 9 RVP conventional gasoline, but a larger<br />
increase in NOx emissions. This comparison assumes that all gasoline meets EPA’s Tier<br />
2 gasoline sulfur st<strong>and</strong>ard <strong>of</strong> 30 ppm. Prior to this program, RFG contained less sulfur<br />
than conventional gasoline <strong>and</strong> produced less NOx emissions. Non-exhaust VOC<br />
emissions with the exception <strong>of</strong> permeation are roughly the same due to the fact that the<br />
RVP level <strong>of</strong> the three blends is the same. However, the increased permeation emissions<br />
associated with ethanol reduces the overall effectiveness <strong>of</strong> ethanol RFG.<br />
An increase in ethanol use will also impact emissions <strong>of</strong> air toxics. We evaluated<br />
effects on four air toxics affected by fuel parameter changes in the Complex Model –<br />
benzene, formaldehyde, acetaldehyde <strong>and</strong> 1,3-butadiene. The most notable effect on<br />
toxic emissions in percentage terms is the increase in acetaldehyde with the use <strong>of</strong><br />
ethanol. Acetaldehyde emissions more than double. However, as will be seen below,<br />
base acetaldehyde emissions are low relative to the other toxics. Thus, the absolute<br />
increase in total emissions <strong>of</strong> these four air toxics is still relatively low.<br />
Table VIII.A.1.b-2 presents the effect <strong>of</strong> blending either MTBE or ethanol into<br />
conventional gasoline while matching octane.<br />
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