Nearly all forms of energy production use large amounts of water.  Coal, which generates nearly 50 percent of the electricity in the U.S., needs water for mining and transport, and to cool and lubricate equipment. Water is also used to cool fuel rods at nuclear plants and to generate steam to power  turbines. The biofuel industry needs water for irrigation, fermentation and the production of ethanol and biodiesel fuels.

Alexander Ochs, director of climate and energy at the Worldwatch Institute, says that adds up to a lot of water. “Per megawatt hour, coal uses 500 to 1000 gallons of water for the production of just one megawatt hour of electricity,” said Ochs. “If we look at all the plants combined in the U.S., all the thermo-electric plants [powered by steam] in the U.S. in 2008 alone, they drew 60 billion to 170 billion gallons of water, per year.”