According to Conservation Magazine’s reporting of an Environmental Science & Technology publication, “It can take 800 gallons of irrigation water to produce the amount of corn necessary to make one gallon of ethanol.”

Here is a breakdown of the amount of water needed to produce the fuels needed to quench our energy needs (Liters per Megawatt hour):

Oil refining: 80-150

Oil Shale: 170-681

Natural Gas Combined Cycle power plants: 230-30,300

Coal: ~900

Nuclear, closed loop cooling: ~950

Geothermal, closed loop cooling: 1,900-4,200

Enhanced Oil Recovery: ~7,600

Natural Gas Combined Cycle power plants, open loop cooling: 28,400-75,700

Nuclear, open loop cooling: 94,600-227,100

Corn ethanol irrigation: 2,270,000-8,670,000

Soybean biodiesel irrigation: 13,900,000-27,900,000

Data: Conservation Magazine July/Sept 2009