A paper by Hill J., et al. Proc. Natl Acad. Sci. USA , doi:10.1703/pnas.0604600103 (2006) concludes while the production of ethanol from maize or biodiesel from soybeans is energetically "cost effective" it is unsound.

 

In straightforward terms, "if all the corn (maize) produced in the United States last year were removed from food supplies and turned into ethanol, just 12% of US gasoline demand would be offset. Turning soybeans into diesel would account for only 9% of US diesel demand. The authors note that neither feedstock could significantly replace petroleum without a serious impact on food supplies.

 

However, the review did find that the amount of energy used in growing, reaping and converting ethanol from maize yields an energy surplus of 25% while soybean biodiesel yields a 93% surplus. Both also reduce levels of greenhouse gas emissions over fossil fuels, but biodiesel much more so.

 

Alex Farrell, an energy expert at the University of California, Berkeley told news@nature.com, "Corn ethanol comes at the price of soil erosion and nutrient runoff. Producing ethanol from cellulose is a much more environmentally preferable option," and David Tilman, on of the papers coauthors believes ethanol obtained through the conversion of the cellulose making up plant fibre is a viable option in the long term.

 

A US Department of Energy report released on July 7 states that biofuels such as cellulosic ethanol could displace 30% of the fuel consumed in US transportation by 2030.