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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Unlike VOC <strong>and</strong> NOx, emissions <strong>of</strong> CO <strong>and</strong> benzene from gasoline <strong>and</strong> diesel<br />
vehicles <strong>and</strong> equipment were estimated to decrease when the use <strong>of</strong> renewable fuels<br />
increased. Reductions in emissions <strong>of</strong> CO varied from as low as 1.3 percent to as high as<br />
3.6 percent for the nation as a whole, depending on both the renewable fuel volume<br />
scenario <strong>and</strong> assumptions regarding the amount <strong>of</strong> ethanol used in reformulated versus<br />
conventional gasoline. Benzene emissions from gasoline vehicles <strong>and</strong> equipment were<br />
estimated to be reduced from 1.7 to 6.2 percent.<br />
We do not have sufficient data to predict the effect <strong>of</strong> ethanol use on levels <strong>of</strong><br />
either directly emitted particulate matter (PM) or secondarily formed PM, but do expect a<br />
net reduction in ambient PM levels to result due to the secondary PM impacts as<br />
discussed in section VIII.C. However, data on direct PM emission impacts is available<br />
for biodiesel. We estimate that reductions in emissions <strong>of</strong> direct PM from the projected<br />
increase in the use <strong>of</strong> biodiesel to be about 100 tons nationwide, equivalent to less than<br />
0.5 percent <strong>of</strong> the diesel PM inventory.<br />
The emission impact estimates described above are based on the best available<br />
data <strong>and</strong> models. However, it must be highlighted that most <strong>of</strong> the fuel effect estimates<br />
are based on very limited or old data which may no longer be reliable in estimating the<br />
emission impacts on vehicles in the 2012 fleet with advanced emission controls 3 . As<br />
such, these emission estimates should be viewed as preliminary. EPA hopes to conduct<br />
significant new testing in order to better estimate the impact <strong>of</strong> fuel changes on emissions<br />
from both highway vehicles <strong>and</strong> nonroad equipment, including those fuel changes<br />
brought about by the use <strong>of</strong> renewable fuels. We hope to be able to incorporate the data<br />
from such additional testing into the analyses for other studies required by the Energy Act<br />
in 2008 <strong>and</strong> 2009, <strong>and</strong> into a subsequent rule to set the RFS program st<strong>and</strong>ard for 2013<br />
<strong>and</strong> later.<br />
We used the Ozone Response Surface Model (RSM) to estimate the impacts <strong>of</strong><br />
increased use <strong>of</strong> ethanol on ozone levels for the 7.5 billion gallon use scenario<br />
representing the required volumes under the RFS program. We did not evaluate other<br />
renewable fuel volumes scenarios due to the limited amount <strong>of</strong> time available for<br />
completing this NPRM. The ozone RSM approximates the effect <strong>of</strong> VOC <strong>and</strong> NOx<br />
emissions in a 37-state eastern area <strong>of</strong> the U.S. Using this model, we projected that the<br />
changes in VOC <strong>and</strong> NOx emissions could produce a very small increase in ambient<br />
ozone levels. On average, ozone levels increased by 0.06 ppb, which represents less than<br />
0.1 percent <strong>of</strong> the st<strong>and</strong>ard. Even for areas expected to experience a significant increase<br />
in ethanol use, ozone levels increased by only 0.1 - 0.2 ppb, less than 0.2 percent <strong>of</strong> the<br />
st<strong>and</strong>ard. These ozone impacts do not consider the reductions in CO emissions<br />
mentioned above, or the change in the types <strong>of</strong> compounds comprising VOC emissions.<br />
Directionally, both <strong>of</strong> these effects may mitigate these already small ozone increases.<br />
The ozone impacts also do not consider the impact <strong>of</strong> increased emissions from ethanol<br />
<strong>and</strong> biodiesel production facilities or any corresponding decrease in emissions from<br />
refineries.<br />
3 Advanced emission controls include close-coupled, high density catalysts <strong>and</strong> their associated electronic<br />
control systems for light-duty vehicles, <strong>and</strong> NOx adsorbers <strong>and</strong> PM traps for heavy-duty engines.<br />
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