What is ethanol waste?

Sugar cane can be used to make ethanol.

Ethanol, or grain alcohol, is a high-octane, renewable biofuel commonly produced from corn, sugarcane, and other sugar crops. Ethanol residue is an important co-product of the ethanol manufacturing industry. Also known as “distillery grains”, it is essentially the porridge left over from the ethanol production process. Initially discarded as industrial waste, several commercial uses for this waste have been developed by the evolving industry.


Two primary production processes are used in the manufacture of corn ethanol: dry mill and wet mill. The main difference between the two processes is the co-products each generates. Ethanol residue is a co-product of the dry milling production process, while gluten feed is a co-product of the wet milling process.

Dry ethanol production is a relatively simple process. Basically, it involves grinding, fermenting and distilling corn from the field. During the fermentation process, corn starch is converted into ethanol. This ethanol is distilled into alcohol, leaving distillery grains behind.

Waste ethanol can be a highly nutritious feed for livestock.

Once the ethanol has been extracted, the residue is usually dried and sold, usually as a livestock feed product or livestock dietary supplement. It is sold in several forms, including Distillery Dried Grains with Solubles (DDGS), Distillery Solubles (DDS) and Distillery Dried Grains (DDG). DDGS is the most common form marketed to the animal feed industry. From every 56 pounds (25.4 kg) bushel of corn, 2.7 gallons (10.2 liters) of ethanol and about 17 pounds (7.7 kg) of waste are produced. For every 1,000 bushels (25.4 metric tons) of corn used in ethanol production, about 8 tons (7.2 metric tons) of DDGS are produced.

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Waste ethanol is highly nutritious feed for cattle, poultry and swine. Thanks to the dry mill production process, it contains nutrients in concentrations three times higher than the original corn input. This is because the process only consumes the starch content of the corn, which makes up more than two-thirds of the grain. Any remaining nutrients are concentrated in the waste, creating a valuable livestock feed product.

The resulting product is particularly valuable as a high-protein, high-energy supplement. Calves and lactating cows, for example, may need protein and energy supplementation, and grain meets both of these requirements. Furthermore, as it contains very little starch, it offers the added benefit of not impairing fiber digestion.

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