Web edition: February 20, 2008
As energy visionaries contemplate greener routes for urban commutes, discussions frequently turn to electric vehicles — either gasoline-electric hybrids or dedicated electric-only cars. Sure, they’ll save on consumption of those precious fossil fuels and cut emissions of noxious air pollutants. What doesn’t usually enter into the discourse, however, are the likely trade-offs in another essential resource: water.
And big trade-offs there’ll be, according to researchers at the
Carey W. King and Michael E. Webber tallied the water used to extract and refine oil. It comes to about a third of a gallon of water per vehicle mile traveled by gasoline-powered vehicles in the United States, they report in paper posted early online Feb. 20 in Environmental Science & Technology.
For comparison, they summed the water used to mine fossil fuels or uranium and then generate electricity. The latter fuels are used to generate almost 90 percent of
Water withdrawal refers to water taken from a lake, stream or other source, then used to cool electric-generating equipment. Because this water is eventually released to the environment, it’s not actually consumed, but this water’s availability is required to provide electrical power and to perform key industrial processes.
A switch from gasoline- to electric-powered vehicles could threaten local water resources, the authors argue. Indeed, they conclude: “Some relatively wet regions of the
There are ways to get around the problem … somewhat. The
Bottom line: We Prius owners must not get smug. Resource economists remind us there are always trade-offs.