Biofuel emissions tests 'must cover entire production process to quantify benefits'

Calculating exhaust emissions from biofuels tells just half a story, and the whole production process should be investigated to determine any positive environmental impact, a researcher has said.

Biofuels from sources such as crops and forestry offcuts can power cars and feed turbines, and are often mixed with fossil fuels to help reduce overall emissions from vehicles. But as a new EU directive requiring a 70% greenhouse gas cut from biofuels approaches, the emissions from each product coming out of a biorefinery must be calculated, said Edgard Gnansounou from the Ecole Polytechnique Fédérale de Lausanne in Switzerland.

Quantifying emissions from an entire processing chain is “no mean feat,” said the researcher, with variables everywhere. With sugar cane, for example, emissions must be tracked from the growth and harvesting of the crop, to transport, to the biofuel production process and the production of other compounds from by-products.

After five years of work, Gnansounou developed a computer model incorporating all the relevant data for wheat straw, which is used to produce bioethanol, biogas for heating and electricity, and phenol for the chemicals industry.

Gnansounou, who published his work in Bioresource Technology, said he will continue his research on other types of crops.