Ethanol is a renewable fuel made from various plant materials, which collectively are called "biomass." Nearly half of U.S. gasoline contains ethanol in a low-level blend to oxygenate the fuel and reduce air pollution. Ethanol is also increasingly available in E85, an alternative fuel that can be used in flexible fuel vehicles. Studies have estimated that ethanol and other biofuels could replace 30% or more of U.S. gasoline demand by 2030.
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.
Ethanol is a renewable, largely domestic transportation fuel. Its use also supports the U.S. agricultural sector.
Ethanol production is a new industry that is creating jobs in rural areas where employment opportunities are needed.
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%.
Using ethanol as a vehicle fuel provides local and global benefits—reducing emissions of harmful pollutants and greenhouse gases.
Carbon dioxide (CO2) is the primary greenhouse gas implicated in global warming (others include methane and nitrous oxide). CO2 is produced when carbon that had been stored on or within the Earth is released into the atmosphere—such as when fossil fuels are burned. CO2 can also be removed from the atmosphere, primarily by the action of plants, which consume it during photosynthesis.
The CO2 released when ethanol is burned as a vehicle fuel is offset by the CO2 captured when crops used to make the ethanol are grown. As a result, ethanol-powered vehicles produce less net CO2 than gasoline-powered vehicles per mile traveled.
Ethanol is blended with gasoline in various amounts for use in vehicles. Low-level blends, up to E10 (10% ethanol, 90% gasoline), are classified as "substantially similar" to gasoline by the U.S. Environmental Protection Agency (EPA), meaning they can be used legally in any gasoline-powered vehicle.
E85 (85% ethanol, 15% gasoline) qualifies as an alternative fuel under EPAct. E85 can be used in flexible fuel vehicles, which are designed to tolerate the fuel's high ethanol content. E85 cannot be used legally in standard gasoline-powered vehicles.
US Department of Energy