During the Washington International Renewable Energy Conference held in March in Washington, D.C., U.S. Department of the Interior Secretary Dirk Kempthorne said that crops used for ethanol take an enormous amount of water. “To reach our ethanol production target of 7.5 billion gallons per year by 2012 will require 30 billion gallons of water a year to process,” he said, “or the amount of the annual water needs of Minneapolis, Minn. And if just 25 percent of the new corn crop requires irrigation, ethanol will demand more water than the combined annual usage of all cities in Arizona, Colorado, Idaho and Nevada. As we increase ethanol production, we must have a holistic approach that takes into account its impact on water supply.”
During World Water Week, an international meeting held in Stockholm, Sweden, in August, the Stockholm International Water Institute concluded that bioenergy demands are diverting water from food production and that by 2050, the amount of water used to grow and process feedstocks for energy in the world will equal the amount of water used to grow crops to feed the world.
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Also in August, the Roundtable on Sustainable Biofuels, a Switzerland-based think tank that is helping the European Commission to define sustainability criteria for biofuels in the European Union, released the first version of its criteria. The group said that water used for irrigation must not be withdrawn beyond the replenishment capacity of the water table and that water-intensive energy crops must not be established in water-stressed areas. Crops that fit local conditions must be used for the most efficient use of water, the criteria said.
In September, with support and advice from the World Wildlife Fund and Natural Resources Defense Council, members of the international airline industry—including Air France, Air New Zealand, All Nippon Airways, Cargolux, Gulf Air, Japan Airlines, KLM, SAS and Virgin Atlantic Airways—formed the Sustainable Aviation Fuel Users Group, demanding that the cultivation of jet fuel plant sources should not jeopardize drinking water supplies. While ethanol is not a source of jet fuel, it is clear that both government and industry around the world are concerned that the irrigation of crops for energy production might lead to water shortages.
Ethanol and Water Use
Using corn ethanol to power a vehicle consumes more water than using petroleum gasoline. In a report titled “Water Intensity of Transportation” published in the November 2008 edition of the journal Environmental Science & Technology, researchers in the Bureau of Economic Geology and also the Center for International Energy and Environmental Policy in the Jackson School of Geosciences at the University of Texas in Austin, Texas, report that driving a petroleum gasoline-fueled light-duty vehicle—which includes cars, trucks and sport utility vehicles—typically consumes between 9 and 18 ounces of water per mile. However, driving an E85 ethanol-fueled light-duty vehicle can consume between 1 and 62 gallons of water (28 gallons of water on average) per mile—up to 882 times as much as petroleum gasoline—if the ethanol in the E85 blend is processed from corn grain that is harvested from irrigated fields, depending on where the corn is grown. In fact, the amount of water used to irrigate the corn crop has the greatest impact on how much water is used per mile.
Approximately 50 million acres of land worldwide is used for the production of biofuels and about 11.6 trillion gallons of water is used throughout the world annually to irrigate energy crops, according to a report entitled “Biofuels and Implications for Agricultural Water Use: Blue Impacts of Green Energy” published by the International Water Management Institute. However, the global impact of irrigating crops for biofuel production is minor, the IWMI said, and the amount of water that is needed to irrigate energy crops varies widely, depending on which crops are being grown and where.
Individual countries and regions need to assess the local impact of energy crop irrigation, the IWMI said. For example, both China and India might not have enough water resources to grow energy crops for ethanol if they use traditional crops such as corn or sugarcane. China withdraws approximately 2,400 gallons of water for irrigation to grow enough corn to produce 1 gallon of ethanol. India withdraws approximately 3,500 gallons of water for irrigation to grow enough sugarcane to produce 1 gallon of ethanol.
Meanwhile, very little irrigation is used in Brazil to grow sugarcane. According to an IWMI report entitled “Water Use and Impacts Due to Ethanol Production in Brazil,” the total rainfall in the savannahs of Brazil is enough to grow crops there without irrigation. Meanwhile in the United States, only 3 percent of all irrigation is used to grow corn for ethanol, the report said. Overall in the United States, approximately 17 percent of U.S. corn for grain or seed is irrigated, based on the latest available USDA data from 2002, according to Carey King, co-author of the UT study and a research associate at the school.
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