A study from the University of Minnesota evaluated the energetic, environmental and energy cost/benefits of two major transport biofuels in the United States: biodiesel from soybean and bioethanol from corn. The purpose was to determine whether these biofuels are viable alternatives to biofuels. Their study (published in the journal Proceedings of the National Academy of Sciences) involved the use of “life-cycle accounting of direct/indirect inputs in the complete production and in use life cycles.”

From an energetic standpoint, corn-derived ethanol was shown to have 25% more energy relative to its energy input, while biodiesel had 93% energy gain. From an environmental point of view, biodiesel can reduce greenhouse gas emissions (relative to fossil fuels) by 41%, while ethanol could do the same by 12%. However, despite their having a net energy gain and positive environmental benefits, both biofuels cannot completely replace fossil fuels. Furthermore, the use of soybean and corn for biofuel production will have major impacts on food supplies. Researchers found that only 12% of the gasoline demand and only 6% of the diesel demand could be satisfied. Biofuels produced from low input biomass and grown on agriculturally marginal land was seen to provide much greater economic and environmental benefits..