April 1, 2008
What is Ethanol?
(from http://www.eere.energy.gov/afdc/ethanol/what_is.html)
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.
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.
E85: An Alternative Fuel
(from http://www.eere.energy.gov/afdc/ethanol/e85.html)
E85 (85% ethanol, 15% gasoline) is considered an alternative fuel under the Energy Policy Act of 1992 (EPAct). It is used to fuel E85-capable flexible fuel vehicles (FFVs), which are available in a variety of models from U.S. and foreign automakers.
The 15% gasoline content in E85 enables FFVs to operate normally under cold conditions; fueling a vehicle with pure ethanol (E100) creates problems during cold-weather operation. Ethanol can also be mixed with gasoline in lower-level blends, which provide many benefits but are not considered EPAct alternative fuels.
Other than lower gas mileage, motorists will see little difference when using E85 versus gasoline. E85 has about 27% less energy per gallon than gasoline. However, E85 is typically priced lower than gasoline, so that cost per mile is comparable.
E85 Stations
As of 2008, more than 1,400 U.S. fueling stations offered E85 to the more than 6 million FFVs on U.S. roadways. Stations are more common in the corn belt (Minnesota, Iowa, Illinois) but are spreading throughout the country. In fact, E85 is now offered in more than 40 states.
E85 typically costs less than gasoline on a gallon-for-gallon basis but more than gasoline on an energy-equivalent basis..
Ethanol Benefits (from http://www.eere.energy.gov/afdc/ethanol/benefits.html)
Ethanol is a renewable, largely domestic transportation fuel. Whether used in low-level blends, such as E10 (10% ethanol, 90% gasoline), or in E85 (85% ethanol, 15% gasoline), ethanol helps reduce imported oil and greenhouse gas emissions. Its use also supports the U.S. agricultural sector.
Increasing Energy Security
About two-thirds of U.S. petroleum demand is in the transportation sector. Sixty percent of U.S. petroleum is currently imported. Depending heavily on foreign petroleum supplies puts the United States at risk for trade deficits, supply disruption, and price changes. Ethanol, on the other hand, is almost entirely produced from domestic crops today. Its use, and that of other alternative fuels, can displace a significant amount of imported petroleum.
Fueling the Economy
Ethanol production is a new industry that is creating jobs in rural areas where employment opportunities are needed. The Renewable Fuels Association's Ethanol Industry Outlook 2008 Report calculated that in 2007 the ethanol industry added $48 billion to gross domestic product and supported the creation of more than 230,000 jobs.
Reducing Greenhouse Gas Emissions
The carbon dioxide released when ethanol is burned is balanced by the carbon dioxide captured when the crops are grown to make ethanol. This differs from petroleum, which is made from plants that grew millions of years ago. According to Argonne National Laboratory, on a life-cycle analysis basis, corn-based ethanol production and use reduces greenhouse gas emissions (GHGs) by up to 52% compared to gasoline production and use. Cellulosic ethanol use could reduce GHGs by as much as 86%.
To learn more about fuel economy, GHG scores, and air pollution scores for E85-capable flexible fuel vehicles, visit the U.S. Department of Energy/U.S. Environmental Protection Agency's Fuel Economy Guide (http://www.fueleconomy.gov/).