March 21st, 2008

By John DeFore

With World Water Day on Saturday, this is a good time to note a report that those optimistic about alternative auto tech might prefer to ignore. A report last month in Environmental Science & Technology Online suggests that electric vehicles, while a boon for the environment in some ways, “could strain water resources” in regions prone to drought. No, electric cars don’t use water directly. But they use electricity, and most of our current means of generating electricity require water. Water that is heated to make steam to turn turbines. Some power plants lose water to evaporation, others extract it from reservoirs . “All told,” the article says, “electricity generation in the U.S. consumes more water than any other activity except irrigation.”

ES&T’s piece draws on research by University of Texas scholars Carey King and Michael Webber, who have concluded that a plug-in hybrid “withdraws 17 times more water per mile than fueling a gasoline vehicle” and that “replacing 25 percent of U.S. cars, light trucks, and SUVs with electric vehicles would consume roughly an additional 100 Bga [billions of gallons]” of water each year.

(The good news: For what it’s worth, the electricity in non-plug-in hybrids involves no extra water usage, since it’s generated not by a power plant but from the braking action of the car itself.)

The researchers say they’re not trying to discourage the adoption of plug-ins, but simply hope to help policymakers in planning for future needs — building more wind-power generators, for instance, would increase electricity supply without using any more water.

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