Bio-fuels -Ethanol from corn

This article is adapted from Scientific American August 2011 P39 "The False Promise of Biofuels" by David Biello.

Getting energy from ethanol is a tentalising solution to two big US problems, climate change and dependence on oil. Terrorism and soaring oil prices has made the Middle East a liability and rising average global temperatures strengthened the need to find alternative fuel sources for transport.

In theory, biofuels come from plants which absorb carbon dioxide from the atmosphere and when burnt in vehicles, simply release the carbon dioxide back into the atmosphere, making biofuels carbon neutral.

US prodcution of ethanol went from 50 million gallons in 1979 to 13 billion gallons in 2010. A government mandate for ethanol to supply 10% of all transport fuel drove the increase and heavy subsidies, which topped $5.68 billion in 2010, made ethanol relatively affordable.

Ethanol yields very little, if any, net savings in carbon dioxide emission. In the production of the 13 billion gallons, in 2010, 40% of total corn production of 2010 was used. This put pressure on food prices and contributed to fertiliser run-off into water ways.

Unfortunately, corn ethanol is not very energy-efficient and can hardly be called carbon neutral. A great deal of energy is needed to boil off the ethanol from the mixture, where fermentation has taken place, of water and yeast. Without subsidies, ethanol from corn could not compete with oil and its sizeable use would put significant pressure on land management and food production.