24 April 2007
Laughing Gas Levels From Biodiesel Crops Not Funny
by Kate Melville
The wide uptake of biodiesel will not make any difference to global warming and could result in greater emissions of greenhouse gases than from conventional diesel, suggests a new study in Chemistry & Industry.
The study was based on a comparison of the two fuels over their entire lifecycle - from production to combustion. All up, the two fuels were similar, both emitting around the same quantity of carbon dioxide equivalent greenhouse gases. But while conventional diesel emits 85 percent of its greenhouse gases when burnt in the engine, two-thirds of the emissions produced by rapeseed derived biodiesel occur during the farming of the crop.
The culprit is nitrous oxide, otherwise known as laughing gas, which is 200-300 times as potent a greenhouse gas as carbon dioxide. The findings are likely to muddy the waters surrounding the European Union's planned aggressive uptake of biodiesel. The study notes that if the land used to grow rapeseed was instead used to grow trees, petroleum diesel would emit only a third of the carbon dioxide equivalent emissions as biodiesel.
Source: Society of Chemical Industry