NCPA - National Center for Policy Analysis


November 3, 2008

As the search for new fuels intensifies, researchers in Texas report that switching to certain alternative transportation fuels would require much more water than conventional petroleum-based gasoline and diesel vehicles.

Researchers analyzed the intensity of water use for selected fuels:  petroleum, natural gas, unconventional fossil fuels, hydrogen, electricity and 2 biofuels -- ethanol from corn and biodiesel from soy.  They found that vehicles running on electricity and hydrogen produced with electricity require withdrawals (used and returned directly to its source) of up to 20 times more water and consume (not directly returned to its source)  more than 5 times more water than those using petroleum-based gasoline.

Moreover, for light duty vehicles (LDV):

  • The lowest water consumption (less than 0.15 gal gallons of water per mile) and withdrawal (less than 1 gallon of water per mile) rates are for LDVs using conventional petroleum-based gasoline and diesel, nonirrigated biofuels, hydrogen derived from methane or electrolysis via nonthermal renewable electricity and electricity derived from nonthermal renewable sources.
  • LDVs running on electricity and hydrogen derived from the U.S. power grid withdraw 5-20 times as much and consume nearly 2-5 times more water than using petroleum gasoline.
  • The water intensities of LDVs operating on biofuels derived from crops irrigated in the United States at average rates is 28 and 36 gal H2O/mile for corn ethanol (E85) for consumption and withdrawal, respectively; for soy-derived biodiesel the average consumption and withdrawal rates are 8 and 10.
  • Thus, while petroleum-based fuels have had a small impact on U.S. water reserves, alternative fuels could put a much larger dent in the water supply.

But not all fuels are created the same -- hydrogen and electricity can also be derived from renewable energy sources that use no water. 

Source: Editorial, "Alternative Fuels May Drain Dwindling Water Supplies,", October 21, 2008; based upon: Carey W. King and Michael E. Webber, "Water Intensity of Transportation," Environmental Science & Technology, October 15, 2008.

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