In the United States, about 9 billion gallons of bioethanol are produced each year. This bioethanol, derived from corn and other plants, is mixed into the gasoline supply to fuel cars and trucks across the nation.
As a clean-burning alternative to oil, gasoline and natural gas, bioethanol is widely seen as a necessary step in our nation's move to sustainable energy usage. It has been endorsed by Congress and the Obama Administration as part of a broader energy reform package.
However, a recent study from the University of Minnesota reports that, in some regions of the country, the amount of water needed to produce this biofuel may actually take a large toll on the environment, offsetting the potential benefits of this new technology.
The researchers found that a surprisingly large amount of water might be required for growing and harvesting the plants from which bioethanol is derived.
This finding raises a new controversy about whether bioethanol is worth the impacts on our water resources. The study appears in the April 15 issue of the journal Environmental Science and Technology.
According to the study, states with high irrigation needs can take up to 2,100 gallons of water to produce one gallon of ethanol, derived from corn. These are mostly states with dry, warm climates and arid soils that require pumping in large quantities of water for irrigation.
California, New Mexico, Colorado and Wyoming are among the top water users. However, the study identified other states where bioethanol was produced using only a fraction as much water.
Bioethanol is a much-touted alternative energy source supported by the Energy Independence and Security Act of 2007 (EISA) and many green advocates. Because of its chemical makeup, it burns much cleaner than oil and oil derivatives.
Advocates argue that energy harvested from plants will be cheaper and have less of an environmental impact than oil and other petroleum products, which are the dominant energy source in the United States today. They argue that plants are a fundamentally renewable resource unlike the Earth's rapidly dwindling petroleum reserves.
The excessive water consumption highlighted by the new study is especially problematic where the water used for irrigation and biorefinery comes from groundwater reserves, such as the Ogallala aquifer.
The aquifier extends through South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico and Texas, and is the largest underground water reservoir on the continent.
The study finds that in 2008 alone, over 18 percent of the water in the Ogallala aquifer was used by these states for agricultural irrigation. Much of this water went specifically for crops that were destined to be used for bioethanol production.
This is an enormous drain on one of our largest water reserves. Increasing ethanol production in this region will undoubtedly have significant impacts on the aquifer. Indeed, if ethanol is to become a more widespread alternative to gasoline, production will need to be substantially ramped up.
Conversely, many states in the Corn Belt only consume 100 gallons or less of water for ethanol production, making them collectively a more efficient region to produce biofuels. The study's authors argue that most ethanol production should be focused in these regions.
Clearly regional differences must be taken into account in order to produce bioethanol efficiently and with minimal damage to the environment.
The authors of the study conclude that "concerted and immediate action needs to be taken in order to prevent a problem shift from energy supply to water sustainability."
Irrigation needs, where groundwater is the primary source, tend to increase with the geographic expansion of ethanol production.
EISA mandates another 6 billion liters of ethanol production capacity by 2015, so placement of new plants is a point of concern.
The study's authors propose regionally strategic water pricing in order to discourage building new ethanol plants in less irrigation-efficient locations.
Although geographic expansion of ethanol production is a potentially large cause of water depletion, most of the production needed to fulfill the EISA mandate - 90 percent of it, in fact - is already built.
Existing biorefineries produce 51 billion liters of ethanol a year. Therefore, it is imperative that the efficiency of these production sites is improved as the industry grows.
In addition to conservative irrigation practices, improved corn genetics are another way to increase production efficiency, the study suggests.
No new technology is perfect, and depleted water supplies may be an unintended consequence of bioethanol. We will have to find a way to balance our resources and production soon or we may be forced to decide between water and ethanol.
Please note All comments are eligible for publication in The News-Letter.