Making fuels from biomass waste

15 October 2010

Jet and diesel fuel can be produced in a simple economic process using waste products of wood processing and pulp mills, claim US scientists.

World decline in fossil fuel resources, rising oil prices, and an increased awareness in environmental impact has made the search for alternative renewable fuel sources extremely important. Sustainable production of fuels has been attempted using non-food biomass (composed of cellulose, hemicellulose, and lignin) and vegetable oils. But these methods only make light alkanes that are not suitable for use as jet and diesel fuel due to their high volatility, so jet and diesel fuels are currently still reliant on petroleum-based crude oils.

In the search for alkanes more suited for transport fuels, George Huber at the University of Massachusetts in Amherst and colleagues have shown that waste feedstocks from biomass power plants or composite wood manufacturing facilities can be turned into jet fuel in an integrated and economical process.

4 step process produces heavy alkanes suitable for diesel

Huber treats a hemicellulose extract from hardwood trees, a common by-product from the wood manufacturing industry, in a four-step process that includes acid hydrolysis and xylose dehydrogenation, aldol condensation, low temperature hydrogenation, and high temperature hydrodeoxygenation. High yields of 76 per cent are obtained and the cost works out to between $2.06/gal and $4.39/gal, depending on initial xylose concentration, refinery size and overall yield.

'Our society will always have a critical need to produce renewable liquid transportations fuels that can run heavy machinery like jet or diesel engines. It is imperative that we develop inexpensive routes to produce these liquid fuels from our renewable resources,' comments Huber. Though in its beginning stages, Huber hopes it can be developed to a commercial level.

David Shonnard, director of the Sustainable Futures Institute at Michigan Technological University in the US comments, 'this is a significant step forward in achieving sustainable transportation. The economic analysis is also particularly important and the sensitivity analyses highlight promising pathways for improvement.'

Rebecca Brodie


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