Ethanol: 50 Gallons of Water For Each Mile Driven

The water requirements of biofuel production depend on the type of feedstock used and on geographic and climatic variables. Feedstock cultivation, usually row-crop agriculture, is the most water-intensive of biofuel production stages.

The water requirements associated with driving on biofuels can be significant. Assuming conservatively a volumetric water to ethanol ratio of 800 (e.g., for irrigated corn ethanol from Nebraska which excludes processing water requirements), and that a car can drive 16 mi on 1 gal of ethanol (or 2/3 of the mileage from gasoline), this represents about 50 gallons of water per mile driven (gwpm) (or 0.02 mi per gal of water [mpgw]). (Environmental Science & Technology, American Chemical Society, May 1, 2009)