The amount of water used to make bioethanol may be three times as much as previously thought, a new study has found. A gallon of ethanol could require up to 2,100 gallons of water from the farm up to the fuel pump.

The study was conducted by Sangwon Suh and his colleagues of the University of Minnesota in St. Paul and funded in part by USDA/CSREES and the U.S. Department of Energy and the Legislative Citizen's Commission on Minnesota Resources.

Earlier studies figured the amount of water used for a gallon of ethanol to be from 263 to 784 gallons. But these estimates did not account for the widely varied irrigation practices of different regions.

The amount of ethanol produced is expected to rise, therefore igniting concerns over high water usage particularly in areas where there already is water shortages.

Furthermore, there are other studies that have questioned how biofuels can be of any benefit at all because of their energy requirements being far greater than what they provide. They also may not reduce greenhouse gas emissions as much as it was hoped and they stand to increase oceanic dead zones by polluting streams with chemical runoff.