The rapid growth in biofuels production could have far-reaching environmental and economic repercussions according to a report released today (12th June) by researchers at Rice University in the USA. The report, "The Water Footprint of Biofuels: A Drink or Drive Issue?", looks at the effect the water requirement biofuel feedstocks have on the environment.

The Rice team asked if increased biofuel-driven agriculture will affect water-resource availability and degrade water quality. They pointed out that fuel crops require large quantities of water and that water pollution is exacerbated by agricultural drainage containing fertilizers, pesticides and sediment. "These potential drawbacks," which the authors labeled the "water footprint," must be "balanced by biofuels’ significant potential to ease dependence on foreign oil and improve trade balance while mitigating air pollution and reducing fossil carbon emissions to the atmosphere."

The report analyzed the amount of water needed to grow particular crops used to produce biofuels and noted that certain crops yield more biofuel energy while using less land, fertilizer and water. "Thus, from a water supply perspective," the authors said, "the ideal fuel crops would be drought-tolerant, high-yield plants grown on little irrigation water."

The debate over biofuels must also "recognize the impact of increased agricultural activity on water quality as well as water consumption," the authors said. Raising biofuel crops in some areas will require greater use of fertilizers, with the runoff affecting local aquifers and even coastal regions like the Chesapeake Bay and the Gulf of Mexico, it warned.

The report acknowledged, however, that some biofuel sources, like switchgrass and other lignocellulosic options, can "deliver more potential biofuel energy with lower requirements for agricultural land, agrichemicals and water." Accordingly, the authors urged that crops be chosen based on their appropriateness to the local climate and that producers raise crops that can be sustained by rainfall rather than irrigation.

The report, written by Pedro Alvarez, the George R. Brown Professor of Civil and Environmental Engineering, and three colleagues was funded by Rice's Shell Center for Sustainability. It is available at   http://cohesion.rice.edu/centersandinst/shellcenter/research.cfm?doc_id=11975