What is Ethanol?

Ethanol (ethyl alcohol, grain alcohol) is an alcohol-based alternative fuel. It is a clear, colorless liquid made up of a group of chemical compounds whose molecules contain a hydroxyl group, -OH, bonded to a carbon atom. 

Ethanol (CH3CH2OH) can be produced from any biological feedstocks (starch crops) that contain appreciable amounts of sugar or materials that can be converted into sugar, such as starch or cellulose. Examples of feedstocks that contain sugar are sugar beets and sugar cane. Corn contains starch that can be converted into sugar relatively easily, so it is the most commonly used crop. However, ethanol can also be made from barley and wheat. 

A number of cellulosic biomass materials, such as trees and grasses, are made up of cellulose which also can be converted to sugar, although with more difficulty than is required to convert starch. Ethanol made from cellulosic biomass materials instead of traditional feedstocks is called bioethanol. 

Most ethanol is produced in the grain-growing states of the Midwest. It is commonly used to increase octane and improve the emissions quality of gasoline. Ethanol can be blended with gasoline to form an E-10 blend (10 percent ethanol and 90 percent gasoline, or an E-85 blend (85 percent ethanol and 15 percent gasoline). 

The Clean Air Act Amendments of 1990 mandated the sale of oxygenated fuels in areas with unhealthy levels of carbon monoxide. Since that time, there has been strong demand for ethanol as an oxygenate blended with gasoline. In the United States each year, approximately 2 billion gallons are added to gasoline to increase octane and improve the emissions quality of gasoline. 

Blends of at least 85 percent ethanol are considered alternative fuels under the Energy Policy Act of 1992 (EPAct). E-85 is used in flexible fuel vehicles (FFVs) that are currently offered by most major auto manufacturers. FFVs can run on gasoline, E-85, or any combination of the two and qualify as alternative fuel vehicles under EPAct regulations.

* Source: U.S. Department of Energy, Clean Cities Program, Alternative Fuels Data Center