Another nail has been hammered into the corn ethanol coffin. According to researchers at the University of Texas at Austin, the water requirements to produce corn ethanol are significantly higher than producing non-irrigated biofuels, hydrogen generated from renewable energy, or petroleum or diesel fuel.
The researchers compared the amount of water withdrawn (used and returned to the source) and the water consumed (water not returned to the source) per mile traveled in a typical car when powered by gasoline, diesel, corn ethanol, soy-derived biofuels, hydrogen and electricity and obtained the following results:Irrigation, Not Biofuels Themselves, The Problem
Petrol and diesel, non-irrigated biofuels, hydrogen and electricity from renewable resources: <0.15 gal water/mile consumed water and <1 gal water/mile withdrawn water;
Hydrogen and electricity derived direct from the US grid (currently mainly fossil fuel and nuclear power): 2-5 times more consumed water and 5-20 times more withdrawn water;
Irrigated biofuels (corn ethanol): 28 gal water/mile consumed water and 36 gal water/mile withdrawn water;
Soy-derived biofuels: 8 gal H2O/mile consumed water and 10 gal H2O/mile withdrawn water.
Evaluation of Biofuel’s Impact on Water Supply Crucial
In their recommendations, report authors Carey King and Michael Webber write (apologies to the authors for this abbreviated excerpt),
Transportation is yet another area where the nexus between water and energy can potentially create conflicts where they did not exist before. [...] The historical use of petroleum-based fuels has had a small overall impact on US water resources, and the most plausible alternatives have higher water intensities. [...] The difference in water intensity between irrigated and non-irrigated biofuel feedstocks (up to 3 orders of magnitude in gallons per mile) shows the tremendous amount of need to properly plan for their incorporation. Due to water resource limitations at aquifers that are already being used intensively for food crop production, using those same aquifers for fuel production may exceed existing limits.
Full original journal article (here be academia...): Water Intensity of Transportation
via: Energy Efficiency News
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