Add water to produce ethanol. USDA photo
Water could be a sleeper issue in determining how much and what kinds of biofuel crops are grown as a strategy for reducing oil dependence.
In a report published November 30, the Government Accountability Office said that "next-generation" ethanol feedstocks, such as Pacific Northwest timber slash, could reduce biofuel-related water consumption compared to corn. Not enough is known about the water impacts of relying on such feedstocks, however, because ethanol hasn't been produced from them at a large enough scale, the report said.
Water-stingy agricultural practices and use of non-potable water could reduce stress on fresh water supplies, but there are economic and logistical barriers to adopting such methods, the report said.
Water consumed in producing corn-based ethanol varies widely, depending on the region. In the moist corn growing areas of the upper Mississippi River Valley and Great Lakes region, where farmers depend largely on rainfall, ethanol production consumes 10 to 17 gallons of water for every gallon of ethanol produced. The figure includes water used in biorefineries, which totals about 3 gallons for every gallon of ethanol produced. In drier areas of the Midwest where farmers rely much more on irrigation, water consumption can total up to 323 gallons per gallon of ethanol produced.
Among the corn alternatives, use of woody biomass from thinning forests in the Northwest and other forested areas "is not expected to impact water supply," the GAO report said.
The report pointed out that ethanol storage could be a water quality issue. If ethanol-blended fuels leak from storage tanks, "the contamination may pose greater risks than petroleum. This is because the ethanol in these fuels causes benzene, a soluble and carcinogenic chemical in gasoline, to travel longer distances and persist longer in soil and groundwater than it would in the absence of ethanol, increasing the likelihood that it could reach some drinking water supplies," the GAO report said.
Comments
Aren't we going to water the corn anyway, regardless if it goes for ethanol production or animal feed? By the way, the corn used by ethanol plants still does go to animal feed in the form of Dried Distillers Grains with Solubles (DDGS). So actually you get both ethanol and feed with the same amount of water consumed. The words "thinning forests" should be cause for alarm. We already grow the corn, and have plenty of idle cropland for additional supply. We don't have the luxury with forests. A cornstalk grows annually, a tree take 20 years. Do we really want to cut down our forests?
Every crop and all natural vegetation consumes rain water. That’s not unique to corn. Only 15% of the corn crop is irrigated. That fact was omitted. Only 25% of irrigated corn goes to ethanol, 4% of the entire crop. The rest goes to livestock feed. Many crops are irrigated, not just corn. Like Mike said – corn ethanol also produces a livestock feed byproduct. One acre of corn yields 165 bushels, and out of that, we get about 500 gallons of domestic biofuel, 55 bushels of distillers grains feed, 22 gallons of corn oil, and about 150 gallons of cellulosic ethanol from the cobs and stover. So distribute the water consumption across all those products. 29% of our sorghum crop, which consumes 1/3 to 1/2 as much water as corn, is also being used for ethanol. Sorghum accounts for up to 20% of our ethanol feedstock, grown on land less suitable for corn. To Refine: A gallon of gasoline consumes 47 gallons of water. Corn ethanol consumes 3-4 gallons. So what is the author squawking about?
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