Biofuels

While ethanol has been championed as an alternative to petroleum fuels, it mainly helps to reduce dependency on oil producing countries. Diluting gasoline with ethanol can improve engine life, reduce nitrogen gas emissions and, in the best case, will become a cheaper fuel.  When ethanol is made from corn, up to 70% of its energy value is spent on its production. Burning ethanol still produces carbon dioxide. Climate change with extreme weather events threatens corn production in the US, where for decades corn surplus was common. The new competition between ethanol plants and food production suddenly in 2008 became an international issue.  Ethanol can be produced from any plant fiber (cellulose), given improvements in enzymes and production technology. Novozymes and Genencor announced the development of new enzymes that can reduce the production costs of cellulosic ethanol to less than US$0.13 a liter (a best case scenario). Cellulosic ethanol companies such as Poet, in South Dakota hoped to start commercial production by 2012 with cost of $0.53 per liter. As gasoline prices rise, cheaper ethanol will look more and more attractive.

Biofuels burned in diesel engines may have a better environmental profile. Diesel engines can run on a variety light oils including vegetable oils. New sources of biodiesel fuels include non-food plants and algae which can be grown in large fermentation vats. Algae factories and greenhouses could be attached to coal burning electrical generators to use surplus heat and  C02 to  yield  a useful biomass, supplying food and diesel fuel instead of air pollution. 

Hill et al describe the comparative features: "Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. "

In 2009, biofuels cannot replace  petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit government subsidized research and development.

See Jason Hill, Erik Nelson, David Tilman*, Stephen Polasky, and Douglas Tiffany. Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. PNAS | July 25, 2006 | vol. 103 | no. 30 | 11206-11210

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