The European Commission's calculations on the sustainability of biofuels have been thrown into doubt by the findings of new research showing that potential greenhouse gas (GHG) savings did not meet legislative requirements

In a study examining the sustainability of biodiesels made from rapeseed oil, researchers from the Friedrich Schiller University in Germany carried out a series of life-cycle analyses of the fuels and compared the GHG savings generated to those stated as “typical” in Annex V of the Renewable Energy Directive (RED).

While the RED states the production and use of rapeseed biodiesel generates between 38%-45% fewer GHG emissions than the equivalent amount of fossil fuel, the German study found that savings could be as little as 25%.

Under the requirements of the RED, biofuels must generate GHG savings of at least 35% to be considered as “sustainable” but, of the 12 different scenarios examined by academics, only four met this baseline and just two fell within the range calculated by the commission.

“Our results indicate that the ‘sustainability’ of rapeseed biodiesel in the interpretation of RED is at best very questionable, and in most scenarios simply unjustifiable,” the report states.

“Given these striking differences [in emissions savings], as well as the lack of transparency in the EU’s calculations, we assume that the EU seems to prefer ‘politically’ achieved typical and default values regarding rapeseed biodiesel over scientifically proven ones.”

The commission declined to comment on the findings, but a spokeswoman said: “Different studies can come to different results, depending on the assumptions used.”

The RED requires all EU members to ensure 10% of land transport fuel is sourced renewably by 2020. As a result, under the Renewable Transport Fuels Obligation all transport fuels sold in the UK must contain a blend of at least 4% biofuels. This will rise to 5% from April 2013.