Study Finds Water Footprint for Bioenergy Larger Than Other Forms 
of Energy; Bioelectricity the Smallest, Biodiesel the Largest

Interesting to see that sugar beets are actually the most water 
efficient crop for biofuels (in terms of water usage per liter).

http://www.greencarcongress.com/2009/06/wf-20090606.html#more