Willow adds new fuel to bioethanol debate

Media Release
18 November 2009

Willow adds new fuel to bioethanol debate

The humble willow tree is being investigated as a source of biofuel by researchers at The University of Auckland’s Faculty of Engineering.

Alan Macfarlane has completed a doctoral study looking at better ways to convert components of wood into valuable chemicals, including bioethanol. His study was based on willow grown on a farm in Wairoa.

Bioethanol, unlike petroleum, is renewable and carbon neutral. Growing crops to produce it absorbs as much carbon as it releases as a fuel. However, its production from corn has been the subject of a fierce ethical debate over the use of valuable food crops as fuel.

“Woody material, however, can be grown with little energy input, no fertiliser and on marginal land that doesn't compete with food production,” Dr Macfarlane says. “It can also be converted to bioethanol, which can be blended with petrol, is cleaner burning and has the potential to improve the sustainability of the transport energΌ sector.

The problem facing researchers is that the cellulose component of wood is the main source for ethanol production, and separating the cellulose is costly and difficult, requiring high temperatures or acid treatments.

Dr Macfarlane has developed a simple, low energy method to isolate cellulose from wood, but also to speed up the removal of another element called lignin. The 27-year-old found controlling pH was the most important factor in his research being successful.

“Producing a high-quality lignin as a by-product from the process makes good economic and environmental sense. Lignin can be used in place of petroleum products in the manufacture of some types of resin, so there is potential for it to be on sold and further reduce reliance on oil,” he said.

Dr Macfarlane has submitted his thesis, and is continuing to investigate the method under lower temperatures and acid levels, to further reduce the energy use of the process. The findings of his research will be published in 2010.

Dr Macfarlane’s research was completed in the Department of Chemical and Materials Engineering under the supervision of Professor Mohammed Farid and Professor John JJ Chen.

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