Environmental benefit of biofuels is overestimated, new study says June 8, 2012 http://phys.org/news/2012-06-environmental-benefit-biofuels-overestimated-reveals.html
Two scientists are challenging the currently accepted norms of biofuel production. A commentary published today in GCB Bioenergy reveals that calculations of greenhouse gas (GHGs) emissions from bioenergy production are neglecting crucial information that has led to the overestimation of the benefits of biofuels compared to fossil fuels.
The paper suggests that CO2 emissions from biofuels should be counted as CO2 emissions, when most say biofuel CO2 emissions should not be counted. The paper argues that ignoring biofuels CO2 emissions “double counts the carbon absorbed by plants when the bioenergy crops are grown on land already used for crop production or already growing other plants because the bioenergy does not necessarily result in additional carbon absorption.” They suggest instead that “Biofuels can only reduce greenhouse gases if they result in additional plant growth, or if they in effect generate additional useable biomass by capturing waste material that would otherwise decompose anyway.”
Hence the scientists are looking at plants as a source of carbon sequestration, whereas biofuels production takes plant material, converts that plant material into a fuel, burning the fuel, and re-releasing it into the atmosphere.