The UK government has committed itself to some ambitious green energy plans. It sounds good, but is it all hot air? Eoin Gleeson reports

Why the scramble for wind power?

Pressure from Europe. Last year, Britain made a commitment to meet 15% of its total energy consumption from renewable energy by 2020. But with all but one of the UK's ten remaining nuclear stations facing closure over the next 15 years, Britain will also have to replace 40% of its generating capacity over the next six to eight years.

So the Government is hoping to stave off blackouts by boosting British wind generation from four gigawatts (GW) to 25GW, doubling the entire current global fleet of wind turbines in the process. Prime Minister Gordon Brown said his ambition is to build a wind industry that would be "the equivalent for wind power of what the Gulf of Arabia is for the oil industry".

Wind power: what does the plan entail?

The centrepiece of the Renewable Energy Strategy is a plan to build 7,000 new wind turbines over the next 12 years; 4,000 to be located off the coast and 3,000 more dotted around the country. The 4,000 offshore turbines, each the size of Blackpool Tower, will have to be lowered into the seabed at a rate of more than one every working day between now and 2020 - that's a turbine for every half mile of coastline. More than £100bn will need to be invested for the plan to come to fruition.

Wind power: how will it be paid for?

To come up with that £100bn, the Government is laying out a slew of incentives to the private sector. So far, the main mechanism for encouraging wind generation has been through subsidies. Under the Renewables Obligation scheme, electricity suppliers are obliged to buy a set percentage of renewably generated electricity each year. In 2004/05, this stood at 4.9% of the electricity they generated, but this will rise to 10% by 2010. This allows wind farm developers to sell the electricity they generate at double the market price.

But the extra cost will ultimately be passed onto consumers through higher electricity bills, says energy analyst Tony Lodge. The Renewables Obligation scheme, he says, is "a hidden tax on all electricity consumers" and a "huge hidden subsidy" to renewable energy providers. This subsidy currently amounts to "£1bn a year" and will have "totalled some £32bn" by the end of the scheme. Meanwhile, engineer Jim Oswald told the Energy Tribune that relying on wind power would result in major power failures across the UK and up to 50% increases in electricity bills.

Wind power: is it worth it?

Subsidies have certainly been a big success in Texas, where 400ft turbines across the state are delivering electricity at a cost of $0.08 a kilowatt hour. That compares to $0.065 for nuclear and $0.05 for coal. The Texan investment has bred a strong interest in developing wind-generating technology, which will drive the cost closer to that of coal-powered electricity, says The Economist.

But despite advances in "smart turbines" - including rotors developed by aerospace groups, and turbines that flex when the wind blows too strong - the experience of other countries who've invested in wind power is not encouraging. A report by the Centre for Policy Studies on Denmark's experience (see below), found that windmills added no net electricity because back-up power plants had to be kept running for when the wind fails to blow. Germany, Spain and the Netherlands have all cut huge wind power subsidies, having had a few years to examine the benefits.

Wind power: will it work for Britain?

The most obvious concern just now is how the plan will be carried out. As Ambrose Evans-Pritchard points out in The Daily Telegraph, there are only three major manufacturers in the world able to make the large turbines needed offshore - and one of them, German engineering giant Siemens, has already sold out until 2012. On top of that, the world has only one ship able to place these 200-ton turbines.

But even if we solve the logistical problems, we will still need to build at least 20 new conventional power stations to back up the grid when the wind isn't blowing. While the wind farms will be spread over a greater land mass in Britain than in Denmark, increasing the chance that the wind will always be blowing in one area or another, the system will still be unreliable.

A Renewable Energy Foundation study of wind speeds in 2005 found that they varied so much that the back-up demand on conventional plants would have varied from 5.5GW to 56 GW in a single month. That would mean switching a 1,000 MW coal plant on and off 23 times to make up for the shortfall.

The introduction of a national computerised system (or ‘intelligent' grid) to manage the power load could improve reliability. But the best hope for Britain may be to eventually hook our grid up to Europe's network, enabling excess wind in one country to compensate for slumps in another. Until then, Brown's lofty ambitions may remain a pipe dream.

Is wind power as green as it seems?

Demark is the world's most wind-intensive state with more than 6,000 turbines generating 19% of its electricity. But this figure is misleading, says Tony Lodge of the Centre for Policy Studies. Not one conventional power plant has been closed in the period that Danish wind farms have been developed.

In fact, the Danish grid used 50% more coal-generated electricity in 2006 than in 2005 to cover wind's failings. The quick ramping up and down of those plants has increased their pollution and carbon dioxide output - carbon emissions rose 36% in 2006.

Meanwhile Danish electricity costs are the highest in Europe. The Danish experience suggests wind energy is "expensive, inefficient and not even particularly green", says Lodge.