Transport biofuels: Can they help limiting climate change without an upward impact on food prices?

Comprehensive life cycle assessments show that current transport biofuels often do worse than conventional fossil transport fuels as to the emission of greenhouse gases. Biofuels from microalgae grown with present technology and lignocellulosic biofuels from current arable land or land that is to be deforested are unlikely to do better regarding the emission of greenhouse gases than fossil transport fuels. When crops characterized by relatively low fossil fuel inputs and relatively high biomass yields are grown on abandoned agricultural and marginal soils which currently sequester little carbon, cropping for transport biofuels may help in limiting climate change without an impact on food prices. For such cropping one probably has to go beyond the market mechanism. Worldwide, there is some scope for the use of harvest residues in biofuel production. However, European arable soils show on average large losses of soil carbon and this rather favors increased addition of such residues to soils.