Britain’s wind farms almost ground to a halt during the coldest spells in December, it has emerged.
As temperatures plunged below zero and demand for electricity soared, figures reveal that most of the country’s 3,000 wind turbines were virtually still, energy experts say.
During some of the chilliest weather, they were working at less than one-hundredth of capacity, producing electricity for fewer than 30,000 homes.
The National Grid was forced to compensate for the still, cold conditions by cranking up conventional coal and gas-fired power stations.
December was the coldest month in more than a century – and yesterday, as some in northern England, the Midlands and Wales were hit with more snow, residents will have been switching on the heating again. But critics have warned that the UK is becoming too dependent on wind for power.
There are 3,153 working turbines in 283 wind farms across the UK, capable of generating more than 5.2 gigawatts of electricity – enough to power almost three million homes, the wind industry says.
Over the next decade, another 10,000 turbines will go up to meet Europe’s climate change targets. By 2020, the Government says 30 per cent of all Britain’s electricity will be generated by wind.
But at best, turbines work at just 30 to 40 per cent of their capacity. And in cold winter snaps, often caused by vast, slow-moving high-pressure systems over Northern Europe, winds drop to almost nothing.
Helen Chivers, of the Met Office, said cold spells were often accompanied by low winds. ‘It is fairly common in winter to have these high pressure systems that bring cold, still conditions over Britain.’
During December’s cold snaps, the windfarms’ output repeatedly fell sharply, National Grid data shows.
On the coldest day, December 20, the average temperature was minus 5.6C. But just as demand for electricity to heat homes was rising, the winds failed.
That evening the recorded output from the UK’s wind farms dipped to 59 megawatts.
Wind experts say the National Grid only detects half the output of wind farms and that the real figure was 120MW – still only one-fiftieth of maximum capacity.
The following day, when the average temperature was minus 5.2C, turbines were recorded as generating just 20MW. The real figure was probably around 40MW – the equivalent of just 20 turbines at full capacity – powering fewer than 30,000 homes.
Winds dropped again after Christmas. On December 30, the recorded output from wind turbines fell to 25MW at 6.30pm.
John Constable, of the Renewable Energy Foundation, which argues against wind farm expansion, said: ‘When you get a high pressure system at this time of year it can cover most of the UK.
‘The whole of the UK is becalmed just when it gets really cold and when demand for electricity goes up. Regardless of how much wind you have installed you need to have the same amount of conventional stations ready to switch on if the wind fails.’ The wind industry insisted wind was reliable – and that still spells are rare. Nick Medic, of Renewables UK, said if the wind does drop, we can import energy from overseas, or use energy stored in dams.
Yesterday, up to 4in (10cm) of snow fell in some upland areas, Leeds Bradford Airport was closed for several hours and dozens of schools in Yorkshire were shut.
However, a band of rain followed the snow and the Met Office said it was expected to have disappeared by morning. A relatively dry weekend was forecast.