Ethanol is a renewable transportation fuel primarily made from starch crops, such as corn. It is also made from sugar beets and cane or cellulosic materials, such as fast-growing trees and grasses. Nearly one-third of U.S. gasoline contains ethanol in a low-level blend to reduce air pollution
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.
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 25% compared to gasoline production and use (source: Argonne National Laboratory GREET Model). Cellulosic ethanol use could reduce GHGs by as much as 100%.
Methanol
Also known as wood alcohol, methanol can be used as an alternative fuel. The use of methanol has dramatically declined since the early 1990s, and auto makers are no longer manufacturing vehicles that run on it
Methanol's physical and chemical characteristics offer several advantages as an alternative fuel. Benefits include relatively low production cost and a lower risk of flammability compared to gasoline. In addition, methanol can be manufactured from a variety of carbon-based feedstocks, such as coal. Its use could also help reduce U.S. dependence on imported petroleum.
In addition, methanol can be made into hydrogen. Researchers are currently looking at ways to overcome the barriers to using methanol as a hydrogen fuel source for future fuel cell vehicles.