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Introduction In the 1990s, air quality regulations required gasolines in some parts of the U.S. to be oxygenated either in the winter or year-round — gasolines in carbon monoxide (CO) nonattainment areas and federal Phase I and California Phase 2 reformulated gasolines (RFG) (see Chapter 2, Gasoline and Air Quality). But oxygenated gasoline is not new. Oxygenates — primarily ethanol (ethyl alcohol or grain alcohol) — have been added to gasoline for decades. Widespread use of ethanol in the United States began in 1978 when a Nebraska group marketed gasoline containing 10 volume % ethanolas gasohol. The program was a means to increase gasoline availability during the oil embargo. Later, the gasohol name was abandoned, but the use of ethanol continued. By 2001,some 10percent of all the gasoline sold in the United States contained ethanol and 58 percent of the blends contained 10 vol % ethanol. This 10 volume % ethanol blend is sometimes referred to as E10. Much of the early blend was marketed in the Midwestern states, the same region where the bulk of ethanol is produced, but after the 1990 wintertime oxygenated gasoline began, ethanol was mostly used in this program throughout the U.S. Initially, little RFG contained ethanol. The first EPA waiver for MTBE was issued in 1979 for 7.0 vol % and a second waiver for 15.0 vol % was issued in 1988. Wide use of MTBE did not occur until the late 1980s and then its use expanded with the introduction of federal RFG in 1995. After the discovery of MTBE in various fresh-water resources, and because tiny amounts of MTBE affect the taste and odor of drinking water, MTBE and other ethers have been banned in California effective January 1, 2004 and many other states have passed or are considering legislation adopting similar prohibitions. Congress is considering phasing out MTBE nationwide and also is considering a renewable-fuels standard. Banning MTBE and/or adopting a renewable-fuels standard will result in increased usage of ethanol.
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