Fiona Harvey Why the effect of biofuels is so hard to quantify

We wrote on Wednesday about the first anniversary of the UK’s Renewable Transport Fuels Obligation coming into force. Under the RTFO, 2.5 per cent of the UK’s liquid transport fuels were to come from biological sources – plant or animal – by now, rising to 3.25 per cent for 2009-10. The UK has exceeded its first target, with about 2.7 per cent of transport fuels now coming from biofuels – helped, in part, because overall fuel consumption has sunk in the recession. According to the Renewable Fuels Agency, “23,897 million total litres of petrol (including bioethanol) and 25,844 million total litres of diesel (including biodiesel) were supplied in the financial year 2007-08 compared to (provisional figures of) 22,313 million litres petrol and 25,333 million litres diesel in the year 2008-09″.

But a report from Friends of the Earth found that the UK’s use of biofuels, far from cutting greenhouse gas emissions, might have increased them, by 1.3m tonnes according to its reckoning – or the equivalent of putting half a million cars on the road.

That might is crucial, because the truth is that this is merely an educated guess, based on calculations as to how much land it takes to produce biofuels, on average; how much land is therefore displaced from food production by biofuels in order to make up for the shortfall in agricultural land, on average; and the average make-up of land around the world, divided among cropland, non-productive land, forest, waste land, urban land, etc.

By combining these, you can get an estimate of how much extra carbon dioxide might have been produced from turning forest to cropland in order to produce biofuels for the UK market.

But these figures rely on lots of variables and assumptions. Is it really possible to say that if a British farmer sells some of his oilseed rape to a biodiesel plant instead of selling it to supermarkets that a Brazilian farmer must then cut down a bit of the Amazon forest to grow soy to sell the oil?

Of course not. If it were, you could point to increasing soy oil imports to the UK and say, look, these are because of our biofuels policy. But it’s more complicated than that. These things work at a much higher, global level of supply and demand and so it is not possible to exactly quantify the amount of carbon emitted from biofuels indirectly. It is only possible to guess, and the guesses about biofuels vary widely. For instance, ask how much of the increase in world food prices has come from biofuel production and look at the widely differing answers.

Much more work needs to be done on the effect of biofuels on carbon dioxide levels. Some biofuels can certainly provide a direct reduction in carbon dioxide emissions – but the question is whether even these efficient biofuels displace crop production to such an extent that they end up a net contributor to carbon dioxide. They may, or they may not – at present we do not know enough to be sure.