How Does Ethanol Work?

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Ethanol is a grain alcohol and can be used in the same way as gasoline. Most gas stations in the United States use a combination of about 10 percent ethanol and 90 percent gasoline, according to the University of Illinois Extension.

Ethanol can be produced from many sources of starch, such as corn, wheat, potatoes and barley, and from sugar crops such as sugar cane and sweet sorghum. The most abundant crop in the US is corn, so most of the ethanol is produced from corn, making it a renewable, domestically sourced fuel. By using an ethanol blend in vehicles, the U.S. cuts down on its reliance on foreign oil and reduces greenhouse gases. It takes 56 pounds of corn to make 2.8 gallons of ethanol fuel. A by-product of ethanol is distiller grains, which can be fed to livestock. The grains are still good for the animals because starch is the only thing that has been removed, leaving most of the nutrients.

There are three different blends of ethanol fuel: E10, E15 and E85. The number refers to the percentage of ethanol mixed in with the gasoline. E85 contains 85 percent ethanol. E10 and E15 will power all cars, while vehicles must be specially equipped to use E85 fuel. Ethanol has a lower energy content than gasoline, so miles-per-gallon decreases with ethanol. Because of the higher octane concentration, ethanol reduces engine knocking, making it a good additive. Ethanol can also be used in diesel engines.