AT A time when water supplies are scarce in many areas of the US, scientists in Minnesota are reporting that production of bio-ethanol may consume up to three times more water than previously thought.
If so, this is potentially a massive blow to the US’s emerging corn-based biofuels industry, bearing in mind that bio-ethanol is often regarded as the clean-burning energy source of the future.
Sangwon Suh and colleagues warn that annual American bio-ethanol production is currently about 9billion gallons and note that experts expect it to increase in the near future. However, the growing demand for such fuels, particularly corn-based ethanol, has sparked significant concerns about its impact on water availability. Previous studies estimated that a gallon of corn-based bio-ethanol requires the use of 263-784 gallons of water – from the farm to the fuel pump. But these estimates failed to account for widely varied regional irrigation practices, the scientists say.
They have made a new estimate of bio-ethanol’s impact on the water supply using detailed irrigation data from 41 US states. They found that bio-ethanol’s water requirements may have been as high as 861billion gallons of water from the cornfield to the fuel pump in 2007. And a gallon of ethanol may require up to more than 2,100 gallons of water from farm to fuel pump, depending on the regional irrigation practice in growing corn.
However, a dozen states in the Corn Belt consume less than 100 gallons of water per gallon of ethanol, making them better suited to ethanol production.