Despite Scotland’s booming wind sector, turbines are still routinely paid not to spin. The Ferret unpacks why this happens, what makes it so costly, and what it means for your bills.
There have been hundreds of applications for battery energy storage schemes (BESS) across Scotland. They are part of the Scottish Government’s drive to meet net zero targets but some communities oppose them including villagers in Kintyre.
Why are Scottish wind farms paid billions to switch off?
Despite Scotland’s booming wind sector, turbines are still routinely paid not to spin. The Ferret unpacks why this happens, what makes it so costly, and what it means for your bills.
The Ferret is 10 and it’s celebrating the milestone with a refreshed look and renewed commitment to journalism that cuts through the static.
In that spirit, we have launched De-noiser – a new fortnightly series of deep-dive explainers on some of the most complex issues facing Scotland, the UK and beyond.
Whether its culture-war flashpoints, political narratives that don’t quite add up, or long-running problems everyone talks about but no one really explains, De-noiser will cut through the spin and make sense of what’s actually going on.
Talking of spin, today we are looking at why the UK pays hundreds of millions of pounds a year to turn off wind farms — even as bills rise and climate targets loom.
And we want to hear from our members. Got an issue that needs De-noising? Get in touch.
Scotland has more wind farms than ever before, and the number keeps growing. Yet at the same time turbine owners are paid eye-watering sums not to generate power.
Since the start of 2025, the UK is estimated to have spent over £1.3bn turning wind farms off – the vast majority of them north of the border.
It's a counterintuitive arrangement which is increasingly held up by politicians and commentators who are sceptical of green energy as proof that renewables are imposing unnecessary costs on the public.
But why does the UK pay wind farms not to generate electricity? And what does it actually mean for bills? As part of its new De-noiser strand, The Ferret has been investigating.
A top-heavy system
Over the past decade the UK has rapidly expanded its wind sector – but many of the new turbines have been built far from where most electricity is used.
“A lot of the build-out of wind has ended up in Scotland, and in the north of Scotland in particular,” says Callum Maciver, a research fellow at the University of Strathclyde who has written about the issue for the UK Energy Research Centre. “You’ve got the best wind resources, the best access to land, and a supportive political environment from both the Scottish Government and local authorities.”
England and Wales, by contrast, spent much of the past decade with a de facto ban on new onshore wind.
The result is that, on windy days, Scotland’s turbines often produce more electricity than the country needs.
That surplus could be sent south to England where most people live and there is lots of demand. But here the UK runs into a problem.
Britain’s transmission network – the high-voltage “motorways” of the grid – was built for a different era of electricity generation.
For much of the 20th century, coal and gas power plants were built close to the cities and towns they supplied. The grid grew around this model.
It was not designed to move vast quantities of electricity hundreds of miles from wind farms in the Highlands to Yorkshire and the South East.
As a result, there are now parts of the network where a lot of electricity must pass through a limited number of transmission lines.
These become ‘bottlenecks’ because there is a maximum amount of electricity they can carry. If too much electricity is pushed through them, they can overheat or malfunction. This can cause instability and, in some cases, even blackouts
Two bottlenecks matter most for Scottish wind. The first is called the B4 boundary which separates the two transmission regions within Scotland.
Many of the UK’s newest and largest wind farms are located north of this point, and their electricity has to cross B4 before reaching the border.
The second is the B6 boundary along the Scotland-England border – the main corridor for exporting Scottish electricity to the rest of the UK.
When the wind is strong and output from wind farms is high, more electricity is generated north of these boundaries than the cables that cross them can physically carry.
When these 'constraints' on the grid occur, the National Energy System Operator (NESO) steps in to keep the system stable. NESO tells some wind farms north of the boundaries to turn off or reduce output – known as ‘curtailment’.
This happens more often when the grid is undergoing maintenance or upgrades. Sections of the transmission network must be taken out of service so engineers can work safely, reducing available capacity.
Maciver notes that B4 “spent around seven months last year operating with roughly half its usual capacity”. B6 experienced similar levels of outages.
With even less room on the grid, more wind has to be turned off.
Wind farms that are told to turn down production lose the money they would have earned from selling that electricity, so NESO compensates them.
But the electricity they would have produced is still needed elsewhere. So NESO must also pay other generators – usually gas-fired power stations – to increase their output at the same time.
This is done through the Balancing Mechanism, the market NESO uses to make rapid adjustments to supply and demand. Generators submit ‘bids’ to turn down and ‘offers’ to turn up, and NESO selects the lowest-cost combination.
“The expensive side of it is turning gas up,” Maciver says. Gas power stations often receive a premium for ramping up at short notice, and the cost of constraint rose sharply when global gas prices spiked in 2021-22.
Since then constraint costs have continued to rise as more and more wind farms have come online without necessary upgrades to the grid.
Constraint payments aren’t unique to wind – all types of power stations can be asked to turn down – but wind now receives most of them simply because so much of it sits north of the grid bottlenecks.
Why is it the same wind farms switching off?
Some wind farms are curtailed more than others. These are often newer, larger projects which can bid lower prices to turn down. In the Balancing Mechanism, the lowest-priced bids are accepted first.
“The cheapest things to turn down end up being the newest, shiniest plants that have just come online,” Maciver explains.
The effect is that a handful of sites – including Scotland’s biggest offshore wind farm, Seagreen, which could power more than 1.6 million homes – are curtailed over 60 per cent of the time. Maciver says this “looks really bad” but says it is largely a “quirk of the system”.
“Going from five per cent curtailment a few years ago to 10 per cent across the whole fleet with everyone sharing that burden would look less bad than a new wind farm coming online and being curtailed two thirds of the time,” he notes.
How can the problem be fixed?
The widely-touted solution is to increase transmission capacity between Scotland and England. Two subsealinks are in the pipeline and due to come online in 2029, with further projects planned in the 2030s.
These upgrades will not totally eliminate constraint payments, but they should help reduce them.
“Since 2010 we’ve had a policy called ‘connect and manage’ which has been to encourage renewables on to the system,” Maciver says. Policymakers prioritised the rapid deployment of low-carbon electricity to tackle the UK’s contribution to climate change, rather than waiting years for the grid to catch up.
“The problem is we got behind on the grid build,” Maciver argues, noting that it will be more expensive to build new transmission now than it would have been five years ago when interest rates were lower.
In future, battery projects could also help store electricity produced when wind output is high, meaning it can be used at other times and less electricity is wasted. So could pumped hydro schemes – which use reservoirs to store and generate electricity.
A growth in energy-hungry industries, such as data centres and green hydrogen production, could mean more power is consumed here in Scotland.
But while new transmission is built, constraint costs are expected to continue to rise as new turbines come online.
Some communities in areas hosting a lot of wind turbines are now calling for a more hard-line response. They want a moratorium on new wind projects in Scotland, a demand backed by Scottish Tory leader, Russell Findlay.
What does this mean for household bills?
Constraint payments attract big headlines, but what about their impact on bills?
“It’s a difficult story [for the renewables sector]”, Maciver says, “but it’s not a huge impact.” Balancing costs – which include constraint payments – currently add around £50 to the typical annual electricity bill. "It's a cost," Maciver notes, but only a "few per cent" of overall bills.
There will also be costs on the consumer involved with upgrading the grid, but Maciver says this should “trade off” with lower constraint payments.
A recent paper by his colleagues at the UK Energy Research Centre (ERC) found electricity bills had increased by around £150 in real terms since 2021. Around £19 of this increase is a result of increased balancing costs partly as a result of higher constraint payments.
UK ERC’s analysis found around £112 of that real term increase was caused by a growth in wholesale costs – driven largely by gas.
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Paul is an investigative journalist with a focus on the environment, energy and climate change. His work has been featured by Channel 4 News and the UK’s leading newspapers. When not Ferreting he can be found walking and listening to podcasts.
Alastair Brian
Karin Goodwin
