Ethanol(C2H5OH), also known as ethyl alcohol or grain alcohol, is a high octane liquid fuel derived from various plant materials, or “biomass.” It is a renewable, non-toxic, clean burning fuel alternative to traditional fuels that can reduce greenhouse gas emissions by as much as 50%.
Ethanol is produced by fermenting and distilling plant starches, sugars or cellulosic material:
starch: corn, barley, and wheat.
sugar: sugarcane (primary feedstock in Brazil)
cellulosic: wood, corn stalks, rice straw, sugar cane bagasse, pulpwood, switchgrass, algae, and municipal solid waste.
Ethanol’s chemical composition remains the same regardless of the feedstock used for production. Nearly all ethanol is derived from starch- and sugar-based feedstocks due to easy extraction and fermentation, which makes large-scale production affordable. Cellulosic feedstocks, composed of cellulose, hemicellulose, and lignin, require greater processing to release the sugars needed for fermentation, making the process more costly. However, new technologies are being developed to overcome these challenges.
In the United States Yellow Corn #2 is the most commonly used feedstock, utilizing the starch in the corn kernel. Once the starch is extracted the remaining nutrients are used to produce distillers grain, a high-protein livestock feed. One bushel of Yellow Corn #2 yields 2.8 gallons of Ethanol and 17-18 pounds of distiller’s grain. The top 5 ethanol producing states are: Iowa, Nebraska, Illinois, Minnesota, and South Dakota
Pure ethanol is not used as a fuel, but is blended with unleaded gasoline. The most common blends:
E10: 10% ethanol and 90% unleaded gasoline blend
The most common low concentration blend is E10, also known as “gasohol.” It is a universal fuel additive to boost gasoline octane levels - allowing more complete fuel combustion and reducing carbon monoxide emissions. All gasoline vehicles have been approved to use blends of up to 10% ethanol by auto manufacturers. E10, however, is not considered an alternative fuel under EPAct regulations.
E15: 15% ethanol and 85% unleaded gasoline blend
E15 is another low-level ethanol blend that has becoming increasingly common. Similar to E10, E15 does not qualify as an alternative fuel under EPAct.
E85: 85% ethanol and 15% unleaded gasoline blend
E85 by convention is a blend 85% ethanol and 15% unleaded gasoline. However, it can be any high-level gasoline blend containing 51% to 83% ethanol. E85 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 designed to run on gasoline, E85, or any mixture of the two. FFVs are available in a variety of models from U.S. and foreign automakers
Ethanol can be found in more than 96% of all gasoline sold, accounting for approximately 10 percent of the nation’s gasoline supply.
Ethanol has been used as an engine fuel or fuel component since the early days of the internal combustion engine (ICE). It has been used for over a century and is a normal component of today’s gasoline. It is a renewable, domestic commodity, which reduces our petroleum reliance and supports local economies (especially in rural areas of the U.S.). Ethanol has proven air quality benefits reducing carbon monoxide, volatile organic compounds, nitrogen oxides, and particulate matter emissions. Additionally, recent studies show Ethanol has a positive energy balance, taking less energy to produce than the energy the fuel provides. Ethanol does have lower energy content than gasoline, which equates to fewer miles per gallon, and its cost and availability are highly variable regionally.
Ethanol Fueling Stations
UCCC Flexible Fuel Vehicle Page
Alternative Fuel Data Center - Ethanol
U.S. Dept. of Energy - EERE - BioEnergy
FuelEconomy.Gov - Ethanol
Ethanol Producers & Consumers
Renewable Fuels Association
American Coalition for Ethanol
BioFuels Water Footprint Tool - Argonne Nat. Lab