Even if we can solve the social and economic questions, are biofuels really environmentally friendly?
Many studies have questioned their carbon neutrality when all the emissions resulting from planting, fertilization, transport and refining are taken into account. More recently, Crutzen and colleagues4 have suggested that the extra emissions of nitrous oxide (a greenhouse gas with a potential impact nearly 300 times greater than carbon dioxide) as a result of microbial action on nitrate fertilizers used in the growth of biofuels may be 3 – 5 times higher than estimated by the recent Intergovernmental Panel on Climate Change. Nor is Jatropha without problems. Although it can grow on marginal land in arid areas, there is little knowledge yet about the level of water and nutrients it will need to generate commercially-viable yields or how it might begin to invade better quality agricultural areas once it is grown in large quantity. Current harvesting and processing techniques are labour-intensive, even though the oil is a known skin-irritant and carcinogen. Many attempts to predict the fu
