Fact Check: How Much Water Does Solar Power Really Use?

Probably a couple gallons per megawatt-hour here, at most | Photo: Brian Kusler/Flickr/Creative Commons License

There's an infographic going around lately that claims to show the relative amounts of water used by four different sources of electrical power: coal, nuclear, natural gas and solar. The graphic claims that solar comes out the clear winner in terms of water conservation, using no water at all to generate power. But is the claim correct? Not quite.

The graphic, produced by the "Climate Reality Project," is making the rounds of social media. It's pretty straightforward, at first glance. Coal-fired power plants use up 1,100 gallons of water for each megawatt-hour of power produced. (A megawatt-hour is about what a typical California household would consume in six or seven weeks.) Nuclear and natural-gas-fired power plants use water 800 and 300 gallons for the same amount of power, respectively. And solar, according to the Climate Reality Project, is the least water-wasteful of all four sources of energy, at zero gallons of water per megawatt-hour.

On Facebook, the graphic's creators share the news breathlessly, saying "Whoa - you probably know that solar power plants produce electricity without producing carbon pollution, but did you all realize they also save so much water? 'Share' to let your friends know, too!" But is the graphic accurate? That depends what you mean by "accurate."

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