Biofuel use can result in higher emissions levels than traditional aviation fuel-that is the conclusion of a new study from the Massachusetts Institute of Technology (MIT).
Researchers at MIT found that the method of production of biofuel has a major influence on the carbon footprint of fuel; enough to make it higher emission than regular petroleum-based aviation fuel, which is renowned for its carbon intensity.
Back in 2008, Virgin Atlantic became the first commercial airline to fly a plane on a blend of of biofuel and petroleum. Since then, Air New Zealand, Qatar Airways and Continental Airlines, among others, have flown biofuel test flights, and Lufthansa is racing to be the first carrier to run daily flights on a biofuel blend.
However, scientists at MIT say the industry may want to reconsider its headlong rush towards biofuels to make sure it has examined the complete carbon footprint before making an all-out push. They say 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,” says James Hileman, principal research engineer in the Department of Aeronautics and Astronautics, who has published the results of a study in the online version of the journal Environmental Science and Technology today. “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.”
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. 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.
To counter the potential harm that biofuel use could do, the researchers recommend looking at fuels such algae and salicornia that don’t require deforestation or fertile soil to grow. Scientists are exploring these as a fuel source, particularly since they also do not require fresh water.
Total emissions from biofuel production may also be mitigated by a biofuel’s by-products. For example, the process of converting jatropha to biofuel also yields solid biomass. For every kilogram of jatropha oil produced, 0.8 kilograms of meal, 1.1 kilograms of shells and 1.7 kilograms of husks are created. These co-products could be used to produce electricity, for animal feed or as fertilizer, reducing the overall environmental impact of the fuel .
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