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Policy Positions: Ethanol and Water

ETHANOL AND WATER

U.S. ethanol producers take great care to ensure that natural resources are used in a responsible and sustainable manner. The ethanol industry understands that meeting increased demand for renewable alternatives to petroleum-based fuels cannot come at the expense of ecological health and environmental quality.

Recently, the water impact of increased ethanol production has come under intense scrutiny. However, when placed in proper context, the facts demonstrate that expansion of the ethanol industry has not had significant impacts on water resources. Further, today’s ethanol industry is more efficient than ever before in its use of water and other natural resources. Whether it’s more efficient water technologies, the use of pre-treated water, or a combination, ethanol producers are dramatically reducing the amount of fresh water needed for production.

As they have done for decades, ethanol producers will continue to seek improvements in production efficiency and embrace technologies and practices that lessen the environmental impacts of production.

THE AMOUNT OF WATER REQUIRED TO PRODUCE ETHANOL CONTINUES TO DECLINE

• Like most manufacturing processes, the production of ethanol requires water for processing and utility systems. Since 2001, ethanol producers have reduced water requirements by 26%, with many plants requiring less than 3 gallons of water to produce ethanol and distillers grains. As recently as 1994, more than six gallons of water were required to produce one gallon of ethanol. Indeed, a 2007 National Academy of Sciences report noted, “consumptive use of water is declining as ethanol producers increasingly incorporate water recycling and develop new methods of converting feedstocks to fuels that increase energy yields while reducing water use.”
• Further reductions in water use are expected in the near term, as new technologies promise to more efficiently use and recycle the water required for cooling towers, boilers and other processing components. Engineering and design firms estimate the average water use per gallon of ethanol produced is likely to continue to drop substantially in the next several years. One such firm estimates water requirements will soon be reduced “…to less than 1.5 gallons per gallon of ethanol produced.”

IN AGGREGATE, THE U.S. ETHANOL INDUSTRY IS A MINOR USER OF INDUSTRIAL WATER

• According to the U.S. Geological Survey, approximately 408 billion gallons of water are used per day for all purposes in the U.S. Industrial water use is estimated at 18.5 billion gallons per day. Based on ethanol production of 10.7 billion gallons in 2009, the industry’s total water use is estimated at 88 million gallons per day. This equates to less than 0.6% of daily industrial water use and about 0.02% of total U.S. water use.
• To put the ethanol industry’s water requirement into proper perspective, consider that daily public water usage by the city of Chicago alone is five times greater than the entire U.S. ethanol industry’s water requirement.
• A typical 50 million gallon per year ethanol plant uses about 400,000 gallons of water per day. This is roughly equivalent to the daily water use of an 18-hole golf course. Water usage at the Sherman Hills Golf Course in Florida, for instance, averaged 363,000 gallons per day over a 12-month period, according to the St. Petersburg Times.
• As is the case with other industries, water withdrawal and discharge at ethanol plants is tightly regulated by state and federal agencies. Ethanol producers must secure local and state permits before during the biorefinery development process. If a proposed ethanol biorefinery were to threaten a particular area’s water supply, the project would not receive the necessary water permits.

PRODUCTION OF PETROLEUM-BASED FUELS REQUIRES SUBSTANTIAL WATER RESOURCES

• When evaluating the costs and benefits of a particular fuel source, it is important make appropriate comparisons to other competing fuels and forms of energy. Though the estimates vary widely, production of gasoline and other petroleum-based fuels requires a significant amount of water.
• According to the National Renewable Energy Laboratory (NREL), “Water use ranges between 65 and 90 gallons per barrel of crude oil processed and wastewater discharge ranges between 20 and 40 gallons, leaving 45 to 50 gallons of water consumed per barrel, or 2 to 2.5 gallons of water per gallon of gasoline.” Thus, using NREL’s conservative estimate, the current per-gallon water requirement for gasoline is similar to that of ethanol. But the aggregate quantity of water required to produce the gasoline consumed in the United States is nearly 1 billion gallons per day.
• It is also important to note that as ethanol’s water use requirement continues to decrease, the water use associated with oil production and refining is expected to increase. This is because nonconventional sources of oil, such as oil shale and tar sands, will increasingly be used to meet increases in oil demand. According to the U.S. Department of Energy, up to three barrels of water are required to produce one barrel of oil from oil shale, meaning more than 6 gallons of water are required to produce one gallon of gasoline from oil shale.

WATER REQUIREMENTS FOR ETHANOL FEEDSTOCKS ARE OFTEN MISUNDERSTOOD

• Critics of the ethanol industry often suggest that biofuels feedstock production consumes massive amounts of water. It is true that corn requires large amounts of water to grow; a bushel of corn needs approximately 4,000 gallons of water in a growing season. But what often goes unreported is that nearly nine out of every 10 corn acres in the U.S. are rain-fed and require no irrigation other than natural rainfall.
• Additionally, much of the water taken into a corn plant is released back into the air through transpiration. In fact, one acre of corn gives off about 4,000 gallons of water per day through evapo-transpiration, according to the U.S. Geological Survey (USGS).
• Future biofuels feedstocks may have even less of an impact on water resources. Field trials for cellulosic energy crops like switchgrass and miscanthus suggest such crops may need less water than corn if groundwater irrigation is necessary. Further, cellulosic feedstocks like agricultural residues, municipal waste, and forestry waste have no direct water use requirement at all.