Wind farms paid £30 million a year to stand idle because the grid can’t cope with all the energy they produce 

Wind farms are being given around £30million a year in compensation to switch off or slow down their turbines because nearly half the electricity they make is not needed.

The cash, which comes from household bills, is paid when the National Grid is unable to cope with the extra power produced during high winds or periods of low demand.

Known as ‘balancing’, the arrangement is intended to compensate firms for energy they are unable to sell.

But as the number of wind farms grows, the rates have hit record levels. Firms are often paid more to turn off their giant turbines than for the electricity they produce.

Last weekend alone, householders handed £3.1million to energy firms for doing absolutely nothing as up to 30 wind farms were paid to switch off.

The energy that could have been produced between Friday and Sunday would have powered up to 12,000 homes for a year.

At one point, 40 per cent of all the wind energy set to be transmitted to the National Grid was instead discarded, with the loss being blamed on maintenance work and breezy conditions.

More than 95 per cent of payments to energy firms last Saturday were to constrain energy produced by wind farms in Scotland because there is limited network capacity between Scotland and the rest of Britain creating a bottleneck of supply.

The amount of wind energy discarded that day was almost twice as much as any other day on record, and cost families £1.9million. It was one of three days since May when wind farms were told to cut their output by more than a third.

On June 30, 46 per cent of energy from turbines was constrained.

In total, payments worth almost £15million have been made this year – more than double the amount given in all of 2012. If the trend continues, the bill for the year will be around £30million.

The figures only relate to giant turbines connected to the national distribution network, which make up 70 per cent of wind power.

There are 5,000 giant turbines across the country, with another 1,000 planned. Under EU law, Britain’s energy consumption from renewables needs to reach 15 per cent by 2020.

Payments known as ‘forward trades’ are also made to energy operators by the National Grid. This is where it agrees a payout in advance when the weather is expected to be stormy.

In 2011, £18.6million was paid in forward trades, although the figure is likely to be much lower this year.

Both payments make up about 1 per cent of a typical household’s electricity spend, according to National Grid.

A spokesman said costs were being driven down and the energy lost last weekend was ‘slightly above average’ owing to a combination of planned summer maintenance and high winds.

But Dr John Constable, director of the Renewable Energy Foundation, said: ‘The increasing volume of discarded wind energy presents a very strong case for revising UK’s ambitious commitment to EU green targets. Allowing subsidised generators to name their price to stop causing problems is a lousy solution.

‘They are abusing their position by holding a pistol to the head of Government and effectively saying we will not get off the grid unless you pay handsomely. Ofgem must do something about this.

‘It’s already a record year and it’s set to be a bumper one looking at the costs. We are on track to spend more on constraining wind than all of the previous years combined. And the problem just seems set to be getting worse.’

Generous taxpayer-funded subsidies for wind farms are set to continue until at least 2020.

Onshore wind farms have been guaranteed at least £100 per megawatt hour, which is a unit of energy equal to using a million watts of power in one hour. This is double the current wholesale rate of £50. Offshore wind farms receive £150.

Last weekend, two Scottish windfarms charged £200 per megawatt hour to shut off.

With greater wind production becoming available all the time, experts warn the overall cost of these payments is set to rise.

Energy analyst Mulu Sun said the spikes in constraint payments may be partly due to a lack of capacity, adding: ‘National Grid’s infrastructure should be keeping pace with the building of wind farms, but that is not necessarily the case. This can cause bottlenecks.’

A spokesman for Ofgem said: ‘We have powers to take action against licensed generators if we consider they are gaining excessive benefit when constraints occur.’

Maf Smith, of the wind industry body Renewable UK, said: ‘Wind is a flexible energy source that can be managed to fit our electricity demands by shutting down and powering up easier and quicker than other forms of energy.

‘That is partly why the National Grid calls on wind developers to constrain their power.’