Corn Ethanol Production

October 02, 2014 Print Friendly and PDF

Corn grain can easily be converted to ethanol (ethyl alcohol). Under current production standards, fuel ethanol facilities can produce about 2.8 gallons of ethanol per bushel of corn. In addition, about 17 pounds of dried distillers grains (DDGs) are produced per bushel of corn. The DDGs are an excellent protein source for cattle. The other component produced in the process of making ethanol is carbon dioxide. Some ethanol facilities are capturing the carbon dioxide to make dry ice or to put into carbonated drinks.

In 2007, the United States harvested 86.5 million acres of corn at a yield of 151.1 bushel per acre ( Based on these figures, one acre of corn would produce about 423 gallons/acre.

Ethanol and Energy

There are common arguments about how much energy is needed to produce ethanol. The majority of current research indicates that ethanol is a net-positive system, with a ballpark estimate of 1.34 (for every unit of energy put into the system, ethanol yields 1.34 units of energy) ( The energy balance question depends on corn yields per acre, technology to produce corn, and technology of the ethanol facilities. In states where corn yields are higher or in facilities where technology is newer, the energy balance is probably even higher.

Some ethanol facilities are increasing efficiency of operation by building cattle feedlots next to the ethanol facilities. DDGs from the ethanol facility are fed to the cattle. Manure from the cattle is captured and put into a digester where methane from the manure is captured and used to generate electricity to run the ethanol facility. Such "closed-loop" systems claim to have much higher efficiencies of production.

Ethanol is not as fuel efficient as gasoline. For blends of E10 (10 percent ethanol) there is no noticeable drop-off in mileage. For blends of E85 (85 percent ethanol), there is a reduction in fuel mileage compared to gasoline.


Ethanol Produced and Future Demand

According to the Renewable Fuels Associaton (, the United States produced about 4.85 billion gallons of ethanol in 2006 and produced about 5.9 billions gallons of ethanol from January through October of 2007.

President George W. Bush signed into law the Energy Independence and Security Act of 2007, which mandates 9 billion gallons of renewable fuels used in 2008 and 36 billion gallons of renewable fuels to be used annually by 2022. Of the total, 21 billion gallons must come from sources such as cellulose (i.e., corn stalks, wood chips, switchgrass, etc.).

Corn-based ethanol, whether from the grain or from the stalks, is likely to be a viable domestic source of renewable fuels in the United States.

For a summary of the act go to:

For the complete text, go to:

For more information on this and other topics related to corn production, contact your state extension corn specialist or your local extension educator/agent.

Here is the link to the corn extension specialists: state extension corn specialists.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.