The U.S. Environmental Protection Agency has proposed a rule change that will make it easier for oil refiners to use ethanol in cleaner-burning gasoline, while still maintaining air quality.
Ethanol, which is added to gasoline to reduce vehicle tailpipe emissions, also causes gasoline to evaporate more readily, which can increase air pollution. To meet the federal requirement of reformulated gasoline containing at least two percent oxygen by weight in smoggy cities, refiners must change the volatility of ethanol when adding it to gasoline. This raises the price of gasoline. EPA's proposed adjustment allows refiners to slightly increase the evaporative property of gasoline in exchange for the carbon-monoxide reductions derived from using ethanol.
Oil refiners also may choose to add methyl tertiary butyl ether (MTBE), which can pollute groundwater supplies if it is leaked into the environment. With more flexibility to use ethanol, the use of MTBE may be reduced.
EPA will accept public comments on the proposal for 60 days. More information is available at: http://www.epa.gov/otaq/rfg.htm.(Source: U.S. Environmental Protection Agency)