MTBE in Gasoline: Clean Air and Drinking Water Issues

Publication Date: January 2004

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Energy; Environment

Type:

Abstract:

Concern over water contamination caused by the gasoline additive methyl tertiary butyl ether (MTBE) has raised questions concerning the desirability of using the additive as a means of producing cleaner burning fuel. MTBE has been used by most refiners to produce the reformulated gasoline (RFG) required under the Clean Air Act in portions of 17 states and the District of Columbia. It is credited with producing marked reductions in carbon monoxide emissions; RFG has also reduced emissions of toxic substances and the volatile organic compounds that react with other pollutants to form smog. Over the last few years, however, incidents of drinking water contamination by MTBE, particularly in California, have raised concerns and led to calls for restrictions on its use. In March 1999, Governor Davis of California ordered a phase-out of MTBE use in the state by December 31, 2002 (later amended to December 31, 2003). Sixteen other states, including New York, have subsequently enacted limits or phase-outs of the substance.

EPA responded to initial reports of water contamination by intensifying research and focusing on the need to minimize leaks from underground fuel tanks. As reports of contamination spread in 1998 and 1999, however, EPA’s position evolved. On March 20, 2000, the Agency announced it was beginning the process of requiring a reduction or phase-out of MTBE use under Section 6 of the Toxic Substances Control Act. Because regulatory action could take years to complete, EPA urged Congress to amend the Clean Air Act to provide specific authority to reduce or eliminate use of the substance. Since then, the Senate Environment and Public Works Committee has reported bills to provide such authority three times (S. 791 in the 108th Congress). Language similar to S. 791 passed the Senate in its version of H.R. 6, the comprehensive energy bill, July 31. The House approved somewhat different MTBE provisions in its version of H.R. 6, April 11. The conference report on the bill includes more extensive assistance for MTBE producers – some of it controversial. The House adopted the conference report November 18. It awaits Senate action.

If MTBE were removed from gasoline without amending the Clean Air Act, there would be a need for refiners to use alternative sources of oxygen in RFG. The potential alternatives are other forms of ether, or alcohols such as ethanol. Ethanol is the most likely substitute, but it costs more to produce than MTBE, poses challenges to the gasoline distribution system, and, some studies suggest that it increases the risk of water contamination compared to non-oxygenated gasoline.
Also, in the short term, ethanol is unlikely to be available in sufficient quantity to replace MTBE nationwide. Gasoline that meets the performance requirements for RFG without using oxygenates at all can be made, but current law requires the use of oxygenates in RFG.

The principal issues for Congress are whether MTBE use should be limited or phased out and whether there should be a “safe harbor” from product liability lawsuits for gasoline refiners and marketers who used MTBE.