MIT researchers have suggested that conventional fossil fuels may sometimes be a “greener” choice than bio fuels.
They said that when a biofuel”s origins are factored in — for example, taking into account whether the fuel is made from palm oil grown in a clear-cut rainforest — conventional fossil fuels may sometimes be the “greener” choice.
“What we found was that technologies that look very promising could also result in high emissions, if done improperly,” said James Hileman, principal research engineer in the Department of Aeronautics and Astronautics.
“You can”t simply say a biofuel is good or bad — it depends on how it”s produced and processed, and that”s part of the debate that hasn”t been brought forward,” added Hileman.
Hileman and his team performed a life-cycle analysis of 14 fuel sources, including conventional petroleum-based jet fuel and “drop-in” biofuels: alternatives that can directly replace conventional fuels with little or no change to existing infrastructure or vehicles.
In particular, the team found that emissions varied widely depending on the type of land used to grow biofuel components such as soy, palm and rapeseed. For example, Hileman and his team calculated that biofuels derived from palm oil emitted 55 times more carbon dioxide if the palm oil came from a plantation located in a converted rainforest rather than a previously cleared area. Depending on the type of land used, biofuels could ultimately emit 10 times more carbon dioxide than conventional fuel.
“Severe cases of land-use change could make coal-to-liquid fuels look green,” said Hileman, noting that by conventional standards, “coal-to-liquid is not a green option.”
The study is detailed in the journal Environmental Science and Technology.