THE government’s renewable energy policy is in chaos after hundreds of wind farm companies were told that they face delays of more than 10 years before they can sell any of the electricity that they produce.

Green energy targets are under threat because the national grid is unable to cope with the large numbers of wind farms applying for connection.

Producers are being asked for "security" payments worth millions of pounds to build turbines that could lie idle for a number of years.

The government has said it wants 10% of all of Britain’s electricity to come from green sources by 2010. In Scotland Jack McConnell wants 40% of electricity to come from renewables by 2020.

However, these targets now appear hopelessly ambitious because ministers seriously overestimated the number of wind farms that could be accommodated by the country’s existing electricity network.

In Britain 117 wind farm schemes have already joined the grid, including more than 30 north of the border. A further 250 wind farms — comprising 6,500 turbines — are at different stages of the planning process in Scotland.

Without expensive upgrades to transmission lines, high winds could cause the network to overload if they were all connected now.

Many have been told that they will not be connected until at least 2016, with some facing even longer delays. However, the national grid is demanding financial guarantees from companies before embarking on expensive upgrades.

Maf Smith, chief executive of Scottish Renewables, the body representing Scotland’s renewable energy industry, said that the lengthy delays meant some companies might have to pull out. "Given the industry is trying to help tackle climate change and create jobs, it’s frustrating to be given a lengthy bureaucratic system which is penalising companies," he said.

Richard Ford, head of grid technical affairs at the British Wind Energy Association, said: "The [national grid] is building up a queue in northern Scotland which means long delays and we have concerns over the large sums of security being demanded. It’s possible that some wind farm proposals will collapse."

Among the 170 companies in the queue are Farm Energy, a Devon-based company that has planning consent for six turbines on the Western Isles. It has been given a connection date of 2013 and must pay a fee of more than £10m. "We don’t have that kind of money and we can’t afford to play this game," said a spokesman. "This is such a ludicrous situation — we have to believe that someone will find a solution."

The grid queue is the latest setback for developers chasing windfalls from the rush for green energy. Plans for an overground cable running from Beauly in Inverness-shire to Denny in Stirlingshire to carry power generated by a number of wind farms, including a £411m wind farm scheme on the Isle of Lewis, is facing stiff opposition from communities.

A spokesman for the national grid said: "We have had an unprecedented level of new connection applications. Combined with the growth of renewable projects across the country, there is a need to upgrade capacity.

"We are fully aware that some of the dates are a little later than some people would like. We will try to work with developers to bring the dates forward wherever possible."

The Scottish executive said: "We are concerned that the current system for offering grid connection to new projects is not working as effectively as it might. We hope that the grid queueing system can be revised to assist advanced projects in getting connected to the grid."

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