The Environmental Certification of Biofuels

Bioenergy, including biofuels, could become a substantial tool for mitigatinggreenhouse gas emissions, locally and globally, possibly providing a large fraction ofglobal primary energy supply by 2020. Exactly how large that share will be is notpossible to predict with any precision, being dependent on a complex array ofphysical, social, economic, technical (innovation) and environmental factors. Inaddition, there will be competition for biomass resources between the differentbioenergy sectors (electricity, heat, transport) and alternative uses e.g. for chemicalfeedstocks and materials. There will be synergies too, particularly arising throughadvanced polygeneration and biorefinery supply chains that could help to raiseprimary productivity and raise resource-use-efficiencies.However, assessing the actual environmental impacts of increased bioenergy and inparticular, biofuel usage, will depend sensitively on the scale and mix of technologyoptions employed and on the location. Location is important the fundamental factorsthat govern biomass productivity vary significantly according to site e.g. soil type,climate, including water availability and temperature. Across a range of indicators,one biofuel may not be the same as another, even where the final fuels arechemically and physically identical e.g. anhydrous ethanol derived from wheat,sugarcane, sugar beet, cassava or from residues.