NCPA - National Center for Policy Analysis

No More Oxygen Additives For Gasoline

June 2, 2000

Recent studies have found that adding oxygen derivatives to gasoline does not make it more environmentally friendly. However, the reformulated gasoline program (RFG) mandated by the federal Clean Air Act requires that gasoline have at least 2 percent oxygen content by weight in order to improve fuel combustion. The aim of the requirement was to reduce the level of exhaust emissions, thus improving air quality by reducing the amount of ozone produced.

The most widely used oxygenate, methyl tertiary butyl ether (MTBE) is a suspected carcinogen; due to cases in which MTBE was found to contaminate groundwater, California intends to phase out its use by 2003. The second most used oxygenate, ethanol, is even less environmentally friendly, due to its potential to cause smog.

Studies have shown that:

  • MTBE should be substantially reduced due to its potential negative effects on the water supply, according to a report released by the Environmental Protection Agency (EPA).
  • The addition of MTBE or ethanol has little impact on improving ozone air quality, suggests a study by the National Research Council.

Therefore EPA has recommended that Congress repeal the oxygenate requirement in the current RFG program.

Source: Ben Lieberman, "Running on MTBE: Closing the Pumps on the Oxygen Requirement," On Point, No.50, October 1999, Competitive Enterprise Institute, 1001 Connecticut Avenue NW, Suite 1250, Washington, D.C. 20036, (202) 331-1010; Press Release, "Clinton-Gore Administration Acts to Eliminate MTBE, Boost Ethanol," March 20, 2000, U.S. Environmental Protection Agency.


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