Tuesday, 27 January 2009

Pier-munching gribble may provide breakthrough for biofuels

A wood-boring crustacean that spends much of its time munching through the wooden supports that hold up piers could help provide the next breakthrough in green energy. The gribble uses enzymes in its gut to break down wood and scientists want to employ it to produce climate-friendly biofuels from natural products such as willow and straw.

The work will form part of a £27m project to make second-generation biofuels a commercial reality within 10 years. The new biofuels would not lead to a net release of carbon dioxide but also won't compete with land for edible crops. The money will come from the government-backed Biotechnology and Biological Sciences Research Council (BBSRC) and a coalition of 15 industrial partners including BP and Ceres.

The cash is aimed at funding research to use plants more efficiently as fuel. The cell walls of plants are made of a complex sugar called cellulose, which is usually mixed with a polymer called lignin. Second-generation biofuels are made by breaking down the cellulose and fermenting it to produce fuels such as ethanol or butanol.

One of the major challenges for biologists is to find chemical enzymes that can efficiently break down cell walls which contain cellulose and lignin. The gribble, a tiny shrimp-like crustacean, seems particularly good at this task. "It's single-handedly responsible for gnawing away at several piers on our south coast and, within its intestinal tract, are enzymes that can unlock some of the polymers [in wood-based materials]," said Professor Katherine Smart, a plant scientist at University of Nottingham and one of the leaders of the project.

First generation biofuels are made from crops that store sugars and starches in their grains. "This has two main problems – it diverts away from the food chain but also it's very energy intensive to grow the crops," said Dr Angela Karp of Rothamsted Research. "You have to grow them every year and it requires a lot of nitrogen fertilisers to grow those grains."

Instead, the BBSRC money will be concentrated on waste materials from normal food crops – wheat straw, spent grain – and also plants that are not grown for food production but still produce a large amount of biomass quickly, such as willows and grasses

Smart said there was much to be done in improving the efficiency in extracting a plant's cellulose and then converting it into alcohol. "At the moment we can produce 19g of ethanol from 100g of straw. Based on the current amount of straw not used currently that means we have between 8-10bn tonnes of straw available in the UK for this kind of conversion. That could produce about a 10% of current use of petrol."

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