Interview Plugging in to more water use
NATIONAL RENE WABLE ENERGY L ABOR ATORY
how it is spread across the country, Gleick says. In California, state programs A fully electric car never fills up at cording to the U.S. Geological Surand utilities are working to bump the gas pump, but it does use wavey. Refining gasoline uses some up the number of plug-in hybrid ter. No, the water doesn’t fuel the water too; the new study used this electric vehicles (PHEVs), which car, but power plants use quite a for comparison. would reduce air pollution and bit of water to make the electricity According to King and Webgreenhouse gas emissions. But the that surges through the plug. And ber’s analysis, replacing 25% of U.S. state is also water-stressed and its as more electric vehicles hit the cars, light trucks, and SUVs with water consumption for generating road, power plants will use more electric vehicles would consume electricity could grow more than water. Driving a car on electric60% from 2000 to 2020, according ity consumes three times more to the Electric Power Research water than driving with gasoInstitute. For example, “if Southline, mile for mile, according to ern California Edison is going to new research published in ES&T be running a lot more power at (pp 4305–4311). night for plug-in hybrids, they’re Water use is not an issue that going to need more cooling wapeople typically associate with ter,” Webber says. He notes that plug-in vehicles, which have generating the electricity should many environmental benefits, not be a major problem for utilisay study coauthors Carey King ties. This squares with a study and Michael Webber of the Uniin ES&T (2008, 42, 1185–1190), versity of Texas Austin (UT). which found that “the U.S. curHowever, “adding any additional rently has sufficient spare nightstrain on water can be a probtime electricity capacity to charge lem in some places,” says Weba large fleet of PHEVs,” enough to ber, who is associate director of easily accommodate a light-duty the Center for International Enfleet of one-third PHEVs. ergy and Environmental Policy “We’re not trying to put a at UT. “If you’re in the water-rich black eye on plug-ins,” Webber Northeast, it’s no problem, but says. “They’re very appealing for if you’re in the water-strained a lot of reasons.” They take adElectric vehicles use virtually no water if they Southwest, like Southern Califor- are run on electricity generated from renewvantage of off-peak power capacable resources, such as wind or solar power. nia, it might be a problem.” ity, he notes, and they replace Any power plant that runs oil. Gleick agrees, adding that steam turbines uses water, whether roughly an additional 100 Bgal per water use “is only one of the tradefired by coal, natural gas, or nuclear year of water. “It’s quite a lot,” says offs, the most important being the energy, says King, a mechanical enPeter Gleick, a water expert and emission of greenhouse gases and gineer at the Bureau of Economic president of the Pacific Institute, dependence on foreign oil.” Geology at UT. Many plants conan independent think tank in CaliIn the future, utilities will face sume water by running it through fornia. (He’s also the “very proud rising electricity demand for many cooling towers where it evaporates owner” of a hybrid Toyota Prius, he uses, says Tom Kleckner, a spokesaway. Plants can also tie up water says, which does not plug into the person for the Texas utility Lumiresources via withdrawal, in which grid but uses electricity generated nant. He says planning for water plants recycle water that is drawn from braking power.) will be especially important in from a reservoir. Powering a plug-in Gleick says the total amount of developing new power plants and electric vehicle withdraws 17 times extra annual water consumption notes that efficient technology more water per mile than fueling a calculated in the paper translates and greater use of renewable engasoline vehicle, the authors say. to about 300,000 acre-feet per year. ergy sources can help reduce waAll told, electricity generation “For comparison,” he notes, “the ter needs. “Water is not an issue in the U.S. consumes more water entire urban sector of California— with wind,” he says, because wind than any other activity except irall the residential, commercial, has the benefit of being produced rigation, accounting for about 195 and industrial use—uses about mainly at night, when plug-in ownbillion gallons (Bgal) per day, or 800,000 acre-feet.” The impact of ers could be recharging. nearly half of all withdrawal, acthe extra water use will depend on —ERIKA ENGELHAUPT
4238 ■ Environmental Science & Technology / June 15, 2008
© 2008 American Chemical Society
