Introduction to Water Use in Ethanol Production

Water use in ethanol production facilities is viewed in two ways: 1) the total facility water use and impact on local water supply, and 2) the water used per gallon of ethanol produced. Total facility water use and impact on local water resources depends on the size of the processing facility and how efficient it is in water used per gallon of ethanol produced. So, in fact, these two views are related.

If a facility is drawing water from a ground or surface water source then it may have a significant impact on local water supply conditions.  Aquifer drawdown may affect neighboring water users. Ethanol production facilities can use significant quantities of water, and for this reason the industry, as it has developed, has emphasized water reuse and recycling. The Zero Liquid Discharge concept focuses on reducing consumptive use of water to a minimum. Co-location of ethanol facilities to share water with other industrial users is an additional efficient water practice to reduce impact on aquifers and water supplies.

In the production life cycle of corn-grain ethanol, water for feedstock growth and processing into ethanol, use the greatest amount of water; and water to grow the feedstock dominates consumptive water use. However, the monetary cost to provide this water, and ultimate “water cost” paid, including redirecting water from alternative uses, depends on whether crops are grown with irrigation or without, and how water is treated in ethanol processing facilities. There are vast differences regionally in how water is used in bioenergy production. For more on water use in ethanol production, see BIOEN3, Unit 3.