Ethanol Production Process

For the 2022/23 marketing year, according to the U.S. Department of Agriculture (USDA), total corn supply will amount to 16.37 billion bushels of which 5.32 billion bushels will be used for ethanol and its by-products.

These by-products include wet and dry distillers grains, CO2 and corn oil.

Distillers grains are co-products of the dry mill ethanol process and used as animal feed. According to the U.S. Grains Council, most ethanol plants are dry-grind facilities that extract starch from corn to produce ethanol. The graphic above provides a clear view of the ethanol production process.

The remainder of the corn kernel is used to produce wet distiller grains (WDG) or dried distillers grains (DDG), of which the latter has a longer shelf life, which is then supplied to livestock and poultry producers.

DDGs contain high energy, mid-protein and high digestible phosphorus content which makes it an attractive replacement for traditionally expensive animal feed made from corn or soybean.


Furthermore, the USDA states that one ton of DDG could effectively replace 1.22 tons of feed consisting of corn and soybean meal. In 2021, according to a study by University of Minnesota Extension, Minnesota's ethanol industry produced 3.7 million tons of DDG. The amount produced, the study said, was sufficient to feed 1.8 million cows, 2.2 million pigs and 55.5 million turkeys and chickens. For context, Minnesota farms have 2.3 million cattle, 9.5 million pigs and 49.5 million head of poultry.

Another co-product from the ethanol production process is CO2, which is used to carbonate beverages and make dry ice. More recently, corn oil has also been produced from ethanol production, which in turn is used in the biodiesel production process. Several ethanol producers in Minnesota such as Highwater Ethanol, Al-Corn Clean Fuel, Guardian Energy and Green Plains Renewable produce corn oil.

In 2021, Minnesota's ethanol industry produced 332.2 million pounds of corn oil. The aforementioned study by University of Minnesota said the corn oil produced by Minnesota's ethanol industry could produce 43.1 million gallons of biodiesel or 50 percent of the biodiesel produced by Minnesota's biodiesel plants.