Growing and producing ethanol costs a lot more water than anyone realized. Nevertheless we make some 9 billion gallons worth every year in the US. That's 13 to 17 percent of US corn production—with more coming down the pipeline.
But we could be a lot smarter about the process. Based on water use alone, some places grow reasonably cost-effective bioethanol while others produce an absurdly environmentally expensive brew.
Previous studies estimated that a gallon of corn-based bioethanol uses from 263 to 784 gallons of water from the farm to the fuel pump. But a new study assessed irrigation data from 41 states and found it's as high as 861 billion gallons of water. And some places cost 2,100 gallons of water to produce one gallon of ethanol.
Bottom line: Colorado, Wyoming, Kansas, Oklahoma, California and New Mexico should not be growing ethanol. In the authors' words: Continued expansion of corn production in these regions is likely to further aggravate expected water shortages there.
Better growing states: Michigan, Wisconsin, Ohio, Indiana, Kentucky. The authors conclude: The time left for improving water consumption is limited… and immediate action needs to be taken in order to prevent a problem shift from energy supply to water sustainability.