How a 'green' Britain should look in the year 2020

At least a tenth of the British landscape will have to be transformed by wind farms and specially cultivated crops to produce renewable energy as the Government grapples with the fight against climate change.

Yesterday, the Cabinet unanimously approved the content of the long-awaited energy review, which will be published next week. It will include plans to make sure that by 2020, one fifth of the country's electricity comes from renewable sources. That proportion is to double by 2050.

On top of that, the Government has a target to ensure that by 2010, 5 per cent of the petrol and diesel used by road vehicles comes from renewable sources.

Yesterday, the Tories issued their own proposals for future energy supplies, in which they also promised to "give green energy a chance".

But analysts from Adas, in Wolverhampton, which specialises in supplying advice on the environment, have warned that the targets cannot be met without a huge upheaval in land use. They have calculated that 3 per cent of all land in Britain, almost 7,000 sq km, will have to be filled with wind farms, and about 15,200 sq km given over to "biomass" crops. This implies that thousands of acres of what are now corn fields, orchards or unused wetlands could be transformed in the next few years into tightly packed fields of willow trees or elephant grass. The acreage of bright yellow rape seed, used to produce biodiesel, may also have to triple, from around 300,000 hectares to a million hectares.

One of the most startling innovations could be that old industrial land may be filled with coppice willows as tall as the nearby houses that they will supply with electricity when they are cut down and their wood chips are fed into small local power generators.

Coppice willows' advantages are that they grow very quickly, and will put down roots even in land heavily contaminated with metal. The amount of carbon dioxide produced by burning woodchips from coppice willow is reckoned to be no more than the amount the tree breathes during its life cycle, so its impact on the environment is neutralised. There is currently just one major coppice farm in Britain, in Drayton, near Stratford, run by Adas and the Department of Environment.

Miscanthus, or elephant grass, is another carbon-neutral source of energy, hardly seen in this country outside ornamental gardens. However, a large field packed with coarse, woody grass over 12 feet high may be a good way to fuel a power station but it is not everyone's idea of a beautiful sight. Elephant grass and coppice willow also need a great deal of water.

"Although biomass crops can deliver environmental benefit to be had from these crops, planting them in the wrong place could be an environmental disaster," Chris Brett, senior renewal energy consultant with Adas, said. "It is very important to stress the point that there need to be regional and local strategies."

The employers' organisation, the CBI, welcomed what it saw as a consensus. "Potential investors in much-needed plant, and energy consumers alike, will have much more confidence to act if the two major parties can broadly agree on what needs to be done to create a stable long-term market for energy," the CBI director general Richard Lambert said.

But Labour and the Conservatives attacked each other's energy policies. Alan Duncan, the shadow Trade Secretary, claimed that Labour was intent on building nuclear power stations, which the Tories saw as a "last resort". The Trade Secretary, Alastair Darling, retorted that renewable energy sources would never be able to compete in the "level playing field" promised by the Tories.