Biofuels experts disagree on benefits

With scientists bickering over the benefits or disadvantages of biofuels production, it's hard to know who to believe.

Corn ethanol, already under fire for its role in food price increases, received another blow from the scientific community when a study published in Feb. 8 issue of Science magazine showed that current production methods of biofuels may do more harm for the environment than good.

They could release significantly more carbon into the atmosphere than gasoline production, adding to greenhouse gases and global warming, the study concluded.

Such studies "may misguide policy fuel development," wrote Michael Wang, a researcher at Argonne National Laboratory, in a recent letter sent to the editors of Science.

Wang developed the software analysis tool, known as the GREET model, used in the study reported in Science. He wrote that the study incorporated a few key assumptions that, taken together, exaggerate the greenhouse gas impact of biofuel production.

Two contradictory studies reported that the production of cellulosic ethanol from switchgrass resulted in a net increase in greenhouse gases of 50 percent or reduced greenhouse gases by 94 percent compared with gasoline production.

Wang, who has conducted extensive fuel production analyses of his own, noted in his letter that the recent study used outdated corn yields and assumed that crops used in biofuel production would replace cropland used to grow corn and other food crops, which is not necessarily the case.

The study "modeled a case in which U.S. corn ethanol production increased from 15 billion gallons a year to 30 billion gallons a year by 2015," Wang wrote. However, Congress capped ethanol production at 15 billion gallons a year by 2015 in the 2007 Energy Independence and Security Act "to help prevent dramatic land use changes."

The 2007 energy legislation, signed by President Bush in December, mandates that 36 billion gallons per year of ethanol be a part of the American fuel system by 2022. Almost two-thirds of this ethanol, however, must be derived from non-food sources, necessitating the production of so-called next generation ethanol such as cellulosic ethanol.

Next generation biofuels could be made from plants such as switchgrass and jatropha that grow on land inhospitable to food crops.

Cellulosic ethanol technology developed by Warrenville-based Coskata Inc. in partnership with General Motors Corp. could turn municipal waste, crop residues and non-food crops into low-cost cellulosic ethanol.

Go to an interactive chart comparing the results of studies analyzing the greenhouse gas impact of biofuels production