The road transport industry is also keen to increase the use of biofuels, and an EU directive last year requires 10% of all road transport fuel to come from plants by 2020. Theoretically the fuels are carbon-neutral: when burned they only release the carbon dioxide they absorbed while the plants were growing.
Campaigners argue biofuels are not as sustainable as they seem and say more biofuels would mean the destruction of virgin forests – and the release of their stored carbon – to create agricultural land.
Heinz Ossenbrink, of the EC’s Institute of Energy (IoE), said research carried out by EU-funded scientists increasingly pointed to a long-term problem for large-scale biofuels use, namely the emissions of nitrous oxide. This is about 270 times more potent than carbon dioxide as a greenhouse gas and is released through use of fertilisers to grow biofuel crops. “Some of the older studies don’t take that into account,” he said. “We have now come to less positive values for biofuels.”
The UN’s Intergovernmental Panel on Climate Change does consider the production of nitrous oxide when deciding on the sustainibility of particular biofuels, but errors in its calculations are known to be large.”That’s because there’s such a huge local variation – [emissions] could double from one end of the field to the other and hundreds of times between the fields in the same country and thousands of times around the world,” said Robert Edwards, of the renewable energies unit at the IoE.