The government's scheme to introduce biofuels as a way to cut carbon emissions from road transport has led to extra emissions equivalent to putting 500,000 more cars on UK roads, according to environmentalists.
A new study shows that producing the amount of biofuels required to meet the government's targets in the past year could have inadvertently doubled the overall emissions of CO2 compared with the standard fossil fuels they have replaced. The extra emissions come from forest destruction tied indirectly to growing energy crops.
Biofuels are, in theory, carbon neutral because they only release the carbon dioxide absorbed from the atmosphere by a plant as it grows. But many recent studies have suggested that the indirect effects of producing biofuels can have a negative overall impact.
In several parts of the world, for example, growing biofuel crops such as soy competes for land with food crops, which are then often displaced on to land that has been cleared of forests. A new analysis, carried out for Friends of the Earth (FoE) by environmental consultants Scott Wilson, has estimated the amount of CO2 emitted as a result of this deforestation.
The researchers calculated that the overall carbon cost of clearing forests for biofuels was equivalent to an extra 1.3m tonnes of CO2 emitted into the atmosphere since April last year. That was when the government's Renewable Transport Fuels Obligation (RTFO) was introduced, which mandated fuel suppliers to include at least 2.5% biofuel in their petrol or diesel. Today that requirement rises to 3.3%.
"Until ministers can do their sums properly and can prove that biofuels are actually saving emissions, they do need to put them on hold," said Nick Davies, a biofuels campaigner at FoE.
Soy crops from the US, Argentina and Brazil are used in the most common UK biodiesels and all contribute to the deforestation problem. The FoE study assumed that 10% of the food crops displaced by biofuels would be pushed on to land created by clearing forests.
The researchers allocated this additional land to various agricultural uses and calculated the resulting amount of extra emissions using established models. For example, clearing one hectare of the Amazonian rainforest can release up to 1,000 tonnes of CO2 into the atmosphere, according to the UN's Intergovernmental Panel on Climate Change.
The FoE's concerns were also raised in a government-sponsored review of biofuels published by Ed Gallagher last year. In the study, he recommended that the introduction of biofuels to the UK should be slowed until more effective controls were in place to prevent the inadvertent rise in greenhouse gas emissions caused if, for example, forests are cleared to make way for biofuel production.
Gallagher's report said that if these displacements are left unchecked, current targets for biofuel production could cause a global rise in greenhouse gas emissions and an increase in poverty in the poorest countries by 2020.
His main recommendation, accepted by the government at the time, was to slow down the introduction of the RTFO so that, starting from a base of 2.5% biofuel mixed into petrol and diesel in 2008-09, manufacturers had to increase the proportion by only 0.5% per year. He further added that anything beyond 5% biofuel after 2013-14 should only be agreed by governments if the fuels are demonstrated as sustainable, including avoiding indirect effects such as change in land use.
"Gallagher has slowed down the rate of increase but we don't think that's an adequate response," said Davies. "He raised some serious concerns and, at the moment, they're not being addressed."
A spokeswoman for the Department for Transport acknowledged that the evidence around biofuels was still evolving. "What is not in dispute is the need to develop new, cleaner fuels and break our dependence on oil if we are to tackle climate change," she said.
"Some biofuels have the potential to help us achieve this. So whilst there is no case for pushing forward indiscriminately on those that may do more harm than good, it would be foolish to ignore any potential they do have.
"We have always been clear that biofuels can only make a useful contribution to mitigating climate change if they are sustainably produced. That is why we commissioned an independent review and following its recommendation we agreed to continue to proceed but to do so more cautiously until we are clearer about their wider effects on the environment.
"We believe this strikes a balanced approach based on the best possible science and evidence as it currently stands."
Davies said that, instead of focusing on ramping up biofuels, the government should encourage more proven methods to reduce transport emissions. "They should be investing in first-class public transport systems and smarter cars that actually save on fuel, and more provision for cyclists and pedestrians.
"They are proven to work and don't have the negative side-effects in terms of raising food prices and chopping down the rainforest. We need to put the biofuels obligation on hold until they can show biofuels are actually saving emissions."