>Large quantities of water are needed as well for the production, refining and transport of the fuels that light and heat our homes and buildings, and run our buses and cars.  Every gallon of gasoline at the pump takes about 13 gallons of water to make.

And of course hydroelectric energy requires water to drive the turbines that generate the power.  For every one-foot drop in the level of Lake Mead on the Colorado River, Hoover Dam loses 5-6 megawatts of generating capacity – enough to supply electricity to about 5,000 homes.

In short, energy production is deeply dependent on the availability of water.  And, as a report released last week by the U.S. Department of Energy (DOE) makes clear, as climate change brings hotter temperatures, more widespread and severe droughts, and lower river and lake levels, the nation’s energy supply is becoming more vulnerable. […]

One particularly interesting figure in the report compares the water requirements of seven different types of electric power facilities – nuclear, coal, biopower, natural gas combined-cycle, concentrated solar, photovoltaic solar and wind.  The last two come out as by far the most water-conserving electricity sources.  In contrast to the 20,000-60,000 gallons per megawatt-hour needed for nuclear and coal plants with “once-through” cooling systems, PV solar and wind require only negligible quantities.<