The United Nations’ Intergovernmental Panel on Climate Change (IPCC), which collates research from around the world, predicts with “medium confidence” that average wind speeds over land in large parts of Europe will fall by up to 10pc in the summer months by 2100, under a scenario in which the world stays within its ambitious 1.5 degree global warming target limit. The trend could have a serious impact. The relationship between the speed and energy generation is “very sensitive”, adds Prof Williams. “A 1pc drop in wind speed can imply a 3pc drop in energy generation. So if the IPCC is correct and there’s a 10pc drop in wind speed - that can imply a 30pc drop in energy generation.”
A lull in wind speeds over the summer was felt in boardrooms across Europe. As it blew at its weakest for around 60 years, major energy companies lost millions of pounds in electricity sales.
By September, households started to feel the pain. Coal and gas-fired plants were switched on to make up for loss of wind, compounding a global shortage of gas and pushing electricity prices to record levels.
“It’s very serious,” Mads Nipper, chief executive of Danish oil-turned-wind giant Orsted, told the Financial Times in August, as he warned shareholders of a hit to profits. “It is like you’re a farmer and it doesn’t rain.”
Countries are relying more on wind to meet their energy needs in the rush to slash carbon emissions. The technology accounts for more than 6pc of global electricity, and is set to grow as fossil fuels are muscled out of the way by cleaner sources.
In the UK, turbines on land and dotted around the coast generate about a quarter of domestic electricity over the year. Boris Johnson wants to make wind the backbone of the energy system, with a huge increase in offshore turbines, as part of the legally binding push to net zero.
But events like the wind lull have triggered questions over whether it was a sign of things to come, and how predictable wind patterns are in the long term amid climate change.
It’s an area of growing corporate and scientific research, with huge consequences for energy security and business investment. But much remains unknown.
“Given what we saw in 2021, I think we will see and we need studies to understand [wind trends] better, especially given our increased reliance on wind as an energy source,” says Paul Williams, professor of Atmospheric Science at the University of Reading.
Barely a gust
Scientists have identified a pattern of declining average wind speeds globally, averaging about one mile an hour every thirty years, based on wind speeds since the 1970s. They point to climate change melting snow and ice in the Arctic, which is weakening the temperature difference between the Arctic and the Tropics, slowing down wind speeds.
The United Nations’ Intergovernmental Panel on Climate Change (IPCC), which collates research from around the world, predicts with “medium confidence” that average wind speeds over land in large parts of Europe will fall by up to 10pc in the summer months by 2100, under a scenario in which the world stays within its ambitious 1.5 degree global warming target limit.
The trend could have a serious impact. The relationship between the speed and energy generation is “very sensitive”, adds Prof Williams. “A 1pc drop in wind speed can imply a 3pc drop in energy generation. So if the IPCC is correct and there’s a 10pc drop in wind speed – that can imply a 30pc drop in energy generation.”
The picture is complicated, however. Long-term wind modelling is uncertain and some evidence also points the other way. “There are a good handful of models that say wind speeds could increase,” says Dr Hannah Bloomfield, research associate in climate risk analytics at the University of Bristol.
Wind speeds have picked back up again since 2010, though this reversal is hard to explain, according to Adrian Chappell, professor in climate change impacts at Cardiff University.
While he says it is very difficult to be definitive about future wind trends, he believes one influential factor that has not had enough attention is changes on land. Buildings and vegetation can act as a break on wind speed, for instance. Land use can also affect the amount of carbon dioxide and warmth absorbed, fuelling or reigning in climate change.
He believes “we can explain up to about 50pc of the variability in wind speed in Europe due to the changes in inland surface roughness”.
“Broader wind models we rely on are not very well coupled to the land surface,” says Chappell, arguing that more work around land could help understand wind patterns. “They essentially assume a fixed and static land surface.”
As more attention is paid to the power of the energy source, stock market analysts are picking through the scientific research for clues on wind giants’ earnings. In a recent report on Orsted, Bernstein said academic research on wind speed trends was “unclear and non-conclusive”.
But it added that speeds in the UK have not strayed from the long-term average, and there was some evidence wind gust intensity will increase due to global warming.
In future, “more powerful wind turbines will more than compensate for the impact of lower wind speeds of 0-10pc, should that be the case”, it added. “For existing projects, investors should ignore the ‘noise’ on wind yield data.”
Speaking in November, Orsted’s Nipper stressed the company believed 2021 was “an anomaly” and cited academic research he claimed showed a slight increase in wind speeds over 40 years.
“We continue to be quite convinced that this is something that will over time fully normalise,” he added. “We were also happy to see October, which is a pretty big wind month, actually being slightly above average.”
North Sea capacity
As for the UK, the University of Bristol’s Dr Bloomfield stresses the North Sea is in a strong position to host more wind turbines with or without changes to wind speeds. “We are one of the best places in the world [for wind energy],” she says. “The North Sea is so windy that if you take 10pc off it, it’s not a problem.”
On top of that, she adds, the IPCC’s projections indicate a much lower fall in wind speeds in the North Sea by 2100, more like 2pc.
A paper in the journal Nature at the start of this year pointed to research indicating a 10pc increase to wind resources over the UK over the century, with a slight decline in the Mediterranean. Building turbines in more locations around Britain also helps to make it more resilient.
The energy system needs to be set up to cope with events like the lulls in September, insists Bloomfield. The coal-fired power plants that helped this time are set to retire next year, while the long-term viability of some gas-fired power stations is open to question.
Other back-up measures, such as batteries and other forms of storage such as hydrogen, are still ramping up.
“It’s something we need to be able to plan for, and people shouldn’t forget that it happened. But it’s not going to happen every year,” she says. “It was a really extreme event, incredibly unlikely to happen this year or the year after.”
Another, more immediate problem related to wind speeds in Johnson’s push to quadruple the amount of offshore wind online by 2030, is crowded seabeds which can affect the wind speeds reaching some of the turbines, warns Prof Chappell.
“I think people are starting to realise that maybe we need more regulation of how and where and why wind farms are being developed, not not just from a nuisance perspective but more from a wind resource perspective. The urgency for building wind turbines and reaching net zero may be undermined by not taking a more holistic perspective.”
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