A new paper, reported last week in the Society of Chemical Industry (SCI) magazine Chemistry & Industry, calculated that biodiesel derived from rapeseed grown on dedicated farmland emits nearly the same amount of greenhouse gas emissions per km driven as does diesel from petroleum sources.
Rapeseed is the major renewable-derived biofuel used across Europe.
Analysts compared the emissions of the two fuels throughout their life cycles, from production to combustion in cars. They found if the land used to grow rapeseed were instead used to grow trees, petroleum diesel would emit only a third of the CO2 equivalent emissions as biodiesel.
Petroleum diesel emits 85% of its greenhouse gases at the final stage, when burnt in the engine. By contrast, two-thirds of the emissions produced by rapeseed-derived biodiesel occur during farming of the crop. Crop land emits nitrogen oxide (N2O), which is 200-300 times more potent a greenhouse gas then CO2.
SCI said the results of this analysis should have big implications for policy-makers in Europe. The biofuel, as well as helping to improve energy security, is expected to play an important role in helping to meet the EU's Kyoto commitment to reduce levels of greenhouse gas emissions by 8% by 2012 relative to 1990 levels. It throws that into question.
"The 2003 EU Biofuels Directive aims to increase the levels of biofuels to 5.75% of all transport fuels by 2010, up from roughly 2% currently," a SCI statement said.
Transportation currently accounts for more than a fifth of all greenhouse gas emissions from the EU.
