As a follow-up to a previous entry indicating that biofuels actually pose more health hazards than the conventional gasoline, here comes another report suggesting that biodiesel could potentially result in greater emissions of greenhouse gases in comparison to conventional petroleum-derived diesel.

Analysts at SRI Consulting compared the emissions of greenhouse gases by the two fuels across their overall life cycles from production to combustion in cars.

The results show that biodiesel derived from rapeseed grown on dedicated farmland emits nearly the same amount of greenhouse gas emissions (defined as CO2 equivalents) per km driven as does conventional diesel.

However, if the land used to grow rapeseed was instead used to grow trees, petroleum diesel would emit only a third of the CO2 equivalent emissions as biodiesel.

Whereas petroleum diesel contributes to greenhouse gases when burnt by the engine, most of the emissions from rapeseed-derived biodiesel occurs during farming of the crop. The fields emit Nitrous oxide (also known as laughing gas) which is 200-300x as potent a greenhouse gas as CO2. It seems that the 2003 EU Biofuels Directive which pushes the the use of biofuels as transport fuel could potentially result in greater emissions of greenhouse gases and may thus be counter-productive in terms of meeting EU's Kyoto commitment to reduce levels of greenhouse gas emissions