Ethanol, also known as grain alcohol or ethyl alcohol, is a valuable alternative to petroleum-based transportation fuels. Ethanol is produced by fermenting and distilling simple sugars from biological sources. In Minnesota, most ethanol is produced from corn but it can also be made from other sugar or starch crops like sugar cane, such as in Brazil, or wheat, sorghum and potatoes.
Most ethanol in Minnesota is made in a corn dry milling process where the whole kernel is ground into a powder, mixed with water to form a mash and then cooked with enzymes that turn the starch to glucose. The mash is fermented and distillation helps to separate the ethanol from the solids and water, which become a high quality livestock feed called distillers grains. Many Minnesota plants also produce carbon dioxide which is used for refrigeration or as an industrial chemical.
In the wet milling process, corn is steeped in water and sulfur dioxide before grinding and the germ, fiber, gluten and starch components are separated. The starch can be sold for use in food processing, paper milling and other uses, or, it can be further processed into corn syrup, ethanol, amino-acids or a wide variety of other products. The germ, fiber and gluten can be made into corn oil, livestock feed and many other products. An advantage to the wet mill process is the wider variety of valuable co-products that can be produced.
Cellulosic ethanol is not yet widely commercialized, but many states, including Minnesota are researching this newer manufacturing process that makes ethanol from cellulosic feedstocks. Cellulose is the main component of the cell walls of plants and cellulosic materials that can be made into ethanol include corn stover (leaves, stalks, cobs), wood products, trees and grass. One advantage to using the cellulosic process is the feedstocks can be used to produce the ethanol as well as burned to fuel the ethanol plant, thereby reducing costs and the amount of fossil fuels consumed in production.
In 2007, Minnesota’s ethanol industry generated a total economic impact of approximately $2.27 billion and more than 4,300 jobs. The combined impacts of Minnesota’s corn and ethanol industries provided more than $12 billion and 70,000 jobs in the same year. (See the Minnesota Department of Agriculture’s 2008 report, Economic Impact of the Corn and Ethanol Industry in Minnesota).
Ethanol use benefits the state’s natural resources and public health through a reduction in harmful vehicle emissions. Because it contains 35 percent oxygen, blending ethanol into gasoline results in more complete fuel combustion and thus reduces the carbon monoxide emissions that contribute to smog formation. Ethanol is also a high-octane fuel that displaces toxic octane boosters such as benzene, designated by the U.S. Environmental Protection Agency as a carcinogen. Toxics and particulate matter are the most dangerous air pollutants to humans.
In 2009, Minnesota produced approximately 1.1 billion gallons of ethanol—more than enough to meet current annual consumption of approximately 270 million gallons. The Minnesota Department of Agriculture estimates that by 2013, when state statute requires the blending of 20 percent ethanol into the fuel supply, Minnesota will produce more than 200 times the amount of ethanol consumed in the state (1.12 billion gallons produced for 533 million gallons consumed).
According to the U.S. Department of Energy, 0.74 units of fossil energy are needed to produce 1 unit of energy from corn ethanol. In comparison, one unit of gasoline requires approximately 1.23 units of fossil energy inputs. Cellulosic ethanol is projected to have an even more positive energy balance, requiring about 0.1 units of fossil energy per 1 unit of renewable energy.