Bioethanol ... a drain on water resources?

Article in Science Daily.

The scientists made a new estimate of bioethanol's impact on the water supply using detailed irrigation data from 41 states. They found that bioethanol's water requirements can be as high as 861 billion gallons of water from the corn field to the fuel pump in 2007. And a gallon of ethanol may require up to over 2,100 gallons of water from farm to fuel pump, depending on the regional irrigation practice in growing corn.

If you look at the map, part of the area that is farmed for corn sits on top of the Ogallala Aquifer. Unfortunately, it's a water resource that feeds the nation, and it's beginning to fail. Back in 2007 the non-profit Environmental Defense issued a report on bioethanol and its impact on the Ogallala Aquifer. In the report titled Potential Impacts of Biofuels Expansion on Natural Resources: A Case Study On The Ogallala Aquifer Region (PDF, 18 pages) they state:

In the areas of highest Ogallala Aquifer depletion, new corn ethanol plants currently under construction or planned will increase the region’s ethanol production capacity by 900%. The area currently hosts only five ethanol plants with combined production of 71.5 million gallons per year, but another nine plants, with 639 million gallons per year capacity, are currently under construction. This dramatic expansion of ethanol production has substantial implications for already strained water and grassland resources in the Ogallala Aquifer region.

Water demands associated with individual ethanol plants—due both to ethanol processing and growing corn feedstock—are not exceptionally higher than demands from other industrial or agricultural users, but the construction of new ethanol plants in areas of existing water stress will exacerbate conflicts if water is already scarce. Water demands from new ethanol plants in areas of Ogallala Aquifer depletion may reach 2.6 billion gallons per year for corn-to-fuel processing alone, and between 59 and 120 billion gallons per year for increased water demand if there are local increases in irrigated corn production.

Now, look at those numbers and consider this ... if the above report (at the very top) is true, and water estimates may be 3 times as high as previously considered ... we're talking up to an additional 360 billion gallons of water per year drained out of that aquifer.

Once that water is gone, it's gone. You can't replenish that aquifer any other way that by rainfall, and that's just not going to happen.