14 Mar 2008

Water for Energy for Water for Energy

This article discusses a growing problem:
As the United States tries to lower its dependence on foreign oil by producing more energy from domestic sources such as ethanol, however, it's running low on fresh water.

Water is needed for mining coal, drilling for oil, refining gasoline, generating and distributing electricity, and disposing waste, Gleick said.

"The largest use of water is to cool power plants," he said at a panel of experts on "The Global Nexus of Energy and Water" in Boston last month.

According to Vince Tidwell, a water-management expert at the Sandia National Laboratory in Albuquerque, N.M., more than 40 percent of the water that's withdrawn from rivers, lakes and wells is used for energy. The rest goes mainly for irrigation.

Most of the water used for energy is returned to its source, but by then it's often heated or polluted and of lesser value.

Conversely, vast amounts of energy are needed to pump, transport, treat and distribute water.

For example, the California State Water Project, which pumps water over the Tehachapi mountains to the Los Angeles Basin, is "the largest single use of energy in California," Gleick said.


"Future fuels are likely to be very water-intensive," he said. "They all require a lot of water."

For example, driving one mile on ethanol consumes 600 gallons of water to irrigate the corn from which it's made, Webber said in an e-mail. Even plug-in hybrids, which are touted as the most efficient way to power electric cars, need to withdraw 10 gallons of water for every mile traveled, he said.

"Instead of miles per gallon of gasoline, we're switching to gallons of water per mile," he said.
Bottom Line: There's no free lunch, and we need to count all the ingredients of the lunch we have: Driving a car consumes gas and produces pollution. If that gas is produced in a non-sustainable way (e.g., ethanol with subsidies and intensive resource inputs), there is an additional cost. These costs are financial (taxes and out-of-pocket) and non-financial (pollution, reduced water, political corruption). Do the entire accounting before you believe any "free lunch" stories!

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