What is Ethanol?
Ethanol (CH3CH2OH; also known as ethyl alcohol, grain alcohol, and EtOH) is a clear, colorless liquid. Its molecules contain a hydroxyl group (-OH) bonded to a carbon atom. To learn more, see the fuel properties table on the E85 Specifications page. Ethanol is made of the same chemical compound—and it is the same renewable biofuel—whether it is produced from starch- and sugar-based feedstocks such as corn grain (as it primarily is in the United States) and sugar cane (as it primarily is in Brazil) or from cellulosic feedstocks.
Making ethanol from cellulosic feedstocks—such as grass, wood, crop residues, or old newspapers—is more challenging than using starch or sugars. These materials must first be broken down into their component sugars for subsequent fermentation to ethanol in a process called biochemical conversion. Cellulosic feedstocks also can be converted into ethanol using heat and chemicals in a process called thermochemical conversion. Cellulosic ethanol conversion processes are a major focus of U.S. Department of Energy research.
Ethanol works well in internal combustion engines. In fact, Henry Ford and other early automakers thought ethanol would be the world's primary fuel before gasoline became so readily available. A gallon of pure ethanol (E100) contains 34% less energy than a gallon of gasoline.
Ethanol is a high-octane fuel. Octane helps prevent engine knocking and is extremely important in engines designed to operate at a higher compression ratio, so they generate more power. These engines tend to be found in high-performance vehicles. Low-level blends of ethanol, such as E10 (10% ethanol, 90% gasoline), generally have a higher octane rating than unleaded gasoline. Low-octane gasoline can be blended with 10% ethanol to attain the standard 87 octane requirement. Ethanol is the main component in E85, a high-level blend of 85% ethanol and 15% gasoline.