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.

The chemical compound in ethanol is the same whether the fuel is made from corn grain starch (as it primarily is in the United States) or sugar cane (as it primarily is in Brazil) or from cellulosic materials. Corn and sugar cane are commonly used to make ethanol today.

Ethanol can also be produced from fibrous cellulosic biomass materials, such as grass, vineyard grapes, wood, crop residues, or old newspapers. Breaking these materials down to their component sugars for subsequent fermentation to ethanol is a major focus of U.S. Department of Energy research. Whether made from starch in corn grain or cellulose in corn stalks, ethanol is a renewable, domestic biofuel.

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 ethanol contains one-third 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. Because ethanol has high octane, it is sometimes blended with gasoline in small amounts to boost octane rating. This mixture, in turn, can be used in high-performance engines.

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, 15% gasoline.