E85 is a form of automobile fuel composed of 85 percent ethanol and 15 percent conventional gasoline. While conventional gasoline is a refined derivative of petroleum, most kinds of ethanol are produced from corn. E85 can be used only in special kinds of engines, called "flexible fuel" engines, designed to run on both ethanol and gasoline.
The use of ethanol to power car engines dates from the early 20th century. However, flexible-fuel vehicles gained widespread use only in the late 1990s. According to the U.S. Department of Energy, as of July 2009 more than 1,950 gas stations offered E85, and more than 7 million flexible-fuel vehicles were on the road.
Although E85 is less efficient than gasoline in terms of mileage, it emits fewer greenhouse gases and has a higher octane rating. Its performance in flexible fuel engines is comparable to gasoline, according to Edmunds. The price of E85 varies depending on the price of corn.
E85 is being produced as a response to two main issues: energy independence and climate change. Because the United States consumes more petroleum than it produces, it must import oil, often at great political and economic cost. The production of ethanol affords the country an alternative to this.
Second, the burning of ethanol produces fewer carbon emissions than the burning of conventional gasoline, suggesting that its use might help slow climate change.
Although ethanol has been used as a fuel for vehicles almost since the invention of the automobile--Henry Ford's Model T ran on ethanol--E85 cannot be used in conventional engines, even for short periods of time, without severely damage.
And although E85 is commonly touted as a means of reducing greenhouse gas emissions, its contribution to climate change is uncertain. Although an engine burning E85 produces fewer carbon emissions than a conventional, gasoline-burning engine does, the benefits are less clear when carbon released in the production of ethanol is considered.
Although E85 is not yet available in many parts of the United States, concerns about climate change suggest that its adoption will become more widespread. To increase energy independence and reduce the release of greenhouse gases, many governments are passing laws mandating production of ethanol. The Energy Independence and Security Act of 2007, signed into U.S. federal law in 2007, mandates that 36 billion gallons of biofuels, including ethanol, be produced by 2022.
