SCOTLAND'S wind farms are unable to cope with the freezing weather conditions – grinding to a halt at a time when electricity demand is at a peak, forcing the country to rely on power generated by French nuclear plants.
• Whitelee wind farm near Eaglesham in Lanarkshire which, at 140 turbines, is the largest of its kind in Europe - however, Whitelee and its like are being criticised by sceptics who say the recent cold, still weather has challenged wind power's output claims
Output from major wind farms fell to as low as 2.5 per cent of their potential generation capacity during the cold snap as power demand rose to close to the highest level yet recorded, new figures have revealed.
Meteorologists say extremely cold temperatures can occur only when there is little or no wind and icy pockets of air are trapped close to the ground, prompting accusations from anti- wind-farm campaigners that wind power cannot be relied on to meet Scotland's electricity needs in the depths of winter.
The data, charted on the Balancing Mechanism Reporting System website, which the National Grid uses to monitor UK power generation, also revealed that at times when wind energy was at its lowest, back-up power had to be piped in from France, where the majority of electricity is nuclear-generated.
The Scottish Government is opposed to nuclear power, insisting no nuclear plants will be built in Scotland once Hunterston B in Ayrshire and Torness in East Lothian are decommissioned, in 2016 and 2023 respectively.
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Over the past ten days, when temperatures have plunged across Scotland, the average power generation from Britain's wind developments – the majority of which are in Scotland – was 261 megawatts (MW), just 10.75 per cent of the total possible of 2,430MW.
Last Monday and Tuesday afternoon wind production fell to a major low while electricity usage peaked close to its highest level.
Shortly before 5:30pm on both days, wind power production fell to 62MW and 61 MW respectively – just 2.5 per cent of its total capacity.
At the same time on both occasions, the UK's electricity usage rose to about 60,000MW – one of the highest ever levels of demand. Electricity demand in the UK rarely rises above 60,000MW.
Wind farms are designed to run at an average of 30 per cent of their generation capacity throughout a year.
The lowest point for wind generation over the period came at 10:15am on 21 December, when production from UK wind farms dropped to 17MW for a five-minute period – less than 1 per cent of their potential output.
Consultant Stuart Young, who runs Caithness Wind Information Forum and opposes wind farms, analysed the figures which, he says, show that Scotland needs to reduce its reliance on wind power.
Mr Young carried out the research by analysing data from the website, which follows only major wind farms that are connected directly to the transmission grid – accounting for about half of the UK's wind generation capacity. The majority of the wind farms that have their output analysed on the site are in Scotland.
"It is clear from recent figures that the high demand has come at not long after 5pm, when people are starting to get in from work, have switched their kettles or electric heaters on and are settling in for the night," said Mr Young.
"The wind industry thinks that a time that there is little wind and high demand is very rare, but the fact that Scotland was being racked by gales two months ago doesn't help the situation when it is very cold and still." He added: "When Alex Salmond is switching on his kettle in Edinburgh for his cup of tea, he's probably actually using nuclear power from France to heat his water. The fact is that we cannot rely on wind alone – we need other forms of back-up."
Helen McDade, head of policy for the John Muir Trust, which campaigns to protect wild land, said: "The statistics show that when demand is at its peak because the weather is so cold, output from wind farms is at its lowest. This is a problem we could have to face repeatedly."
However, others insisted that wind output on specific days did not give an accurate picture of the benefit of wind power – claiming that other types of power plant, such as hydro, compensated for low wind-farm output on days when the conditions were still.
Scottish Government figures released last week showed that 27 per cent of Scotland's electricity demand last year came from renewable sources – mainly wind.
Industry body Scottish Renewables recently announced that there were more than four gigawatts (GW) of renewable energy projects in operation – enough to generate 31 per cent of the annual demand for electricity from every home and business in the country – and a further six gigawatts in the pipeline.
The Scottish Government has ambitious targets of generating 80 per cent of Scotland's electricity needs from green energy sources by 2020.
"If you look at any specific outcome during a rare weather pattern, it doesn't present an accurate picture," said Dr Dan Barlow, head of policy for WWF Scotland. "The most recent data from the government shows that renewables generated more than a quarter of Scots' electricity demand. That discredits any claims that wind doesn't work.
"But no-one is suggesting that we should take all of our electricity from wind – if we couple our onshore potential with our vast wave and tidal potential, then we can create a lot of renewables from that mix," he said.
Jenny Hogan, director of policy for Scottish Renewables, said: "Most forms of renewable energy, including wind and wave power, rely on variable yet highly predictable natural resources.
"This means that the energy generated from these sources will vary on different days and at different times of the year. We must therefore look over the course of a full year to gauge accurately the overall generation of renewable energy rather than cherry-pick data on a specific day.
"If Scotland is to be a global leader in renewables and win the massive economic prize this industry presents, we have to maintain our commitment to secure, sustainable energy as well as the economic, environmental and moral imperative to reduce carbon emissions."
Duncan McLaren, chief executive of Friends of the Earth Scotland, pointed to a report published by his organisation last week, which claimed that Scotland could phase out all conventional thermal power by 2030 while maintaining a secure electricity supply – even on days when wind output was zero.
"The question isn't 'is the Scottish system secure?' but is the wider system we're linked into secure?" he said, adding that Scotland could earn money from selling electricity generated from excess wind power overseas.
"We are dedicating effort to a power generation source, which, while in certain conditions may not generate an enormous amount of power, can earn us income the rest of the time."
Environment minister Roseanna Cunningham said: "By definition, wind energy is reliant on wind. But the point is that we are not only focusing on wind energy. We are incredibly lucky that we have such a vast variety of renewables capacity in Scotland."
The research will confirm the observations of many readers who have written pointing out that turbines in their area have been barely turning while homes need extra heat. Page 28