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Last update: 09.07.2011

June 2011

Land-use changes are main factor in carbon emissions from biofuels

Source : forbes.com

Not all biofuels are "green" according to where the crops from which they are derived are grown. The worst offenders are palm oils, which may have ten times the carbon emissions of normal diesel fuel derived from petroleum if the palm is grown on converted rainforest land. In contrast, when the palm is grown on previously cleared land, its emissions are around one fifth that for conventional petroleum-derived diesel. These conclusions are from a life-cycle analysis of 14 different source-fuels made by a team at M.I.T. which takes account of the carbon emissions incurred in the growing and harvesting of the crop, including land-clearance, its processing and the CO2 that results from final combustion of the fuel. Accordingly, it is suggested that biofuels that depend far less on changes in land use may be the cleanest in terms of carbon emissions, including those from salicornia and algae. The latter particularly require smaller areas of land to produce them than their equivalent amount made from land-based crops, and the fertility of that land is not an issue, since they can be grown in tanks or biorectors placed on land of any quality.