Even though concerns about the technical viability, safety and practicality of dropping in sustainable biofuels in the jet fuel mix have largely been settled, the financial case for scaling up this mitigation wedge is still very uncertain. It is understood that first-generation biofuels, of which the feedstock production often threatens biodiversity and competes with food production for water and land, are not an option. Second-generation biofuels address these concerns, and have significantly lower life-cycle emissions than kerosene jet fuel. At the same time their full life-cycle contribution to emission mitigation has yet to be fully established (although the EU currently accepts all biofuels as qualifying as 100 per cent in terms of emissions mitigation).