The energy needed for 40% of Scotland's population was lost at times yesterday as wind turbines shut themselves down to prevent damage.

More than half the total wind energy generation capacity in Scotland was unavailable at one stage.

But, unlike during September's high winds, when wind farm operators were asked to shut down, none of the operators were paid for the shut-downs as there was plenty of capacity on the national gird.

A spokesman for National Grid said: "In very high winds like these, wind turbines shut down for their own protection.

"At lunchtime today, 1500MW of electricity that was expected to be generated by wind farms in Scotland wasn't being produced, although we can't tell if that's all down to the high winds or wind farms just deciding not to generate."

He said that 1500MW was enough to supply about one million homes.

"National Grid hasn't had to pay any wind farms not to generate today. And the company's electricity demand forecasting team had already anticipated wind farms shutting down because of the high winds, and the company had made sure there was enough back-up power available to keep the lights on," he said.

ScottishPower, operators of Europe's largest wind farm Whitelee in East Renfrewshire, as well as 14 others in Scotland, said it was "not a question" of the firm deciding to turn off a wind farm.

A spokesman added: "In high winds the modern turbines will turn themselves off at certain speeds to protect themselves structurally, then they will start turning again when the wind speed drops again. This morning our wind farms were generating approximately 650MW. This would have dropped to around 140MW at the peak of the storms this afternoon."