Coppice solution to energy shortage

November 1, 1996

Iola Smith While England's willows are inextricably linked with wicker baskets or the sound of ball on cricket bat, a Bristol University project aims to develop them as a solution to Europe's timber shortage and as a source of renewable energy.

The university's agricultural research station, at Long Ashton, houses Britain's national collection of willow trees, with over 100 species and hybrids.

Following exhaustive trials of different planting methods, weed and disease control, the university has developed a range of willows that will flourish in virtually any type of soil.

These trees, which grow quickly, could be planted on land that has been taken out of agricultural production.

Bristol reckons that the European Union will have 20 million hectares of surplus agricultural land by the year 2000.

Using Bristol's recommended short rotation coppicing system, willows can be harvested for up to 25 years. It is these harvested stems that can be used to generate electricity.

The stems are cut into wood chip and Bristol calculates that a megawatt of electricity can be generated from every tonne of chips.

If planted densely, each hectare of willows can produce between 12 and 15 tonnes of wood chip a year, producing 12 to 15 megawatts a hectare.

This is generated either by steam turbine or by a gasifier. Long Ashton has a demonstration gasifier which burns willow chips to produce carbon monoxide.

That gas, in turn, powers a generator that produces electricity for farm use.

In the longer term, Bristol is convinced that by using similar gasifiers, farms and small rural industries across Europe could become self-sufficient in electricity.

And they could sell any surplus electricity to the National Grid.

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