Michigan State University Professor of Chemical Engineering Bruce Dale recently sent a letter to colleagues interpreting the analyses by Searchinger et al. and Fargione et al. in Science. In the letter, Dale says, “The Searchinger and Fargione argument at its root is this: corn (and perhaps cellulosic) ethanol is not sustainable because it will divert land use for animal feed (over 70% of corn is fed to animals) to new lands that will release large amounts of greenhouse gases as they are cultivated.”
But Searchinger appears to go beyond accounting the carbon released from newly tilled soils in rainforests and grasslands. He includes as a cost the lost opportunity to store carbon in soils when they are converted from production of food and feed to production of biofuels.
Prior studies all assign to biofuels the benefit of using land to take carbon out of the atmosphere by growing feedstocks, but fail to acknowledge that using land in this way has carbon costs, because it sacrifices other carbon benefits of land.”
“Even in the unlikely event that the world’s farmers could boost increases so high that the need for world cropland declines even with a higher population, each additional gallon of ethanol would still preclude some amount of cropland from reverting to forest or grassland.”
Searchinger’s response and many other useful resources are published on a wiki discussion on the “Current Debate on Land Use” started by The Roundtable on Sustainable Biofuels. The wiki is open to the academic community for debate and discussion of the land use issue.