Every year, we pay multiple millions of pounds to cover the cost of “constraint payments” through our electricity bills. These are payments made to power companies to switch off wind turbines due to the grid the infrastructure being insufficient to move the power from offshore wind farms to the places that need it, predominantly large conurbations in England. This article looks at how this happens, the Scottish Government policies behind it and why building more wind farms like MachairWind isn’t the answer.
What is curtailment of electricity?
Curtailment is when a power generator (e.g. Scottish Power Renewables) is instructed to produce less electricity than it could otherwise generate by NESO (the National Energy System Operator). For wind farms this typically means that the wind is blowing and turbines are capable of generating electricity, but the operator is told to reduce output or shut down turbines because the electricity cannot be used or transported to where it is needed.
This can happen because the network cannot physically carry the power produced, electricity supply is higher than demand, there is insufficient storage capacity or there are risks to grid stability.
Scotland has excellent wind resources but many of the largest demand centres for power are in England. Often, there is more renewable electricity available in Scotland than the grid can transport south.
What are constraint payments?
The national grid has a physical limit on the amount of power that it can safely transmit. Electricity is usually produced a long way from where it is needed, so infrastructure is required to move power across the UK (particularly through the B6 boundary which is the transmission interface between Scotland and England). This transmission system needs extensive upgrades to handle the flow of “green” electricity from where it is produced (mainly Scotland and northern England) to where demand outstrips supply (e.g. midlands and SE England) to prevent the grid becoming overwhelmed and failing. Balancing the grid is an extremely intricate process.
Renewable energy supply often fails to align with demand. On windy days, Scotland can’t transmit or store the amount of electricity produced, so operators are paid to switch off turbines because the energy generated can’t get to where it is needed. On still days or when demand is high, gas generator operators are paid to increase output to ensure demand is met. Payments made to the companies that own these facilities (wind farms and gas generators) are called constraint payments.
How much money is paid out in constraint payments each year?
According to Octopus Energy, over £1.4 billion was spent in 2025 on “wasted wind” (i.e. switching off wind turbines and paying gas plants to switch on). As more wind farms are constructed these costs are set to soar.
Estimates suggest 98% of curtailed wind generation is from Scotland. Examples include Seagreen (Scotland’s largest offshore wind farm located 17 miles from Montrose) being paid to not generate 71% of the time that it could be producing. As a result, the cost of the electricity it does generate is four times higher than it should be! New projects such as Viking on Shetland are seeing similar patterns from day one.
Octopus Energy projects that constraint costs driven by wasted wind energy are on track to cost the UK a staggering £8 billion per year to balance the energy system by 2030.
Pete Miller, Octopus Energy’s Head of Customer Experience, said: “It’s crazy to build wind farms where there’s no grid, then pay them to sit idle, and then pay the most expensive fossil fuel plants to generate the power instead.”
Who covers the cost of constraint payments?
In short, we all do through increased energy bills.
The hard truth is that our bills are rising partly because we continue to build wind farms much faster than we can upgrade the grid to move the power they produce. What’s more, necessary upgrades to the grid to reduce constraint payments are estimated to add around £60 annually to every household’s energy bill in Scotland by 2030.
Why is this so difficult to fix?
- Why not just improve the grid? This will certainly help, but it is expensive, complicated and will take a significant amount of time. Ofgem has approved plans for about £70 billion in high-voltage network upgrades including the Eastern Green Links, a series of subsea HVDC electricity superhighways connecting Scottish wind to English demand. These will connect Torness, Peterhead, Aberdeen and Fife to locations in England. None of these are on Scotland’s west coast and this investment is already running behind schedule and will not be in place for another 4-6 years. The transmission cavalry is coming but not soon enough to prevent constraint payments peaking later this decade.
- Wouldn’t the alternative be to produce energy nearer to key demand locations? For offshore wind developments off the west coast of Scotland like MachairWind, the transmission losses can be higher than for conventional power stations located close to demand centres because the electricity must travel through offshore array cables between turbines, export cables to shore, onshore transmission networks in Scotland and long distances transmission south to the major demand centres in England. As a broad guide, total losses from a remote Scottish offshore wind farm to an English consumer is commonly around 5-10% although this figure varies with cable design and operating conditions.
- How about floating wind farms further offshore instead of fixed bottom turbines in our inland waters? Floating offshore wind turbines can significantly reduce impacts on marine ecosystems and coastal landscapes by avoiding the need for extensive seabed foundations and allowing developments to be located much further from shore. However developers prefer fixed-bottom turbines in shallower waters because they are cheaper and simpler to construct, operate and finance than floating wind farms. Some of Scotland’s most sensitive coastal waters and seascapes are targeted by companies like Scottish Power Renewables precisely because those areas happen to be shallow enough for fixed-bottom technology.
How does the Scottish Government’s Renewable Energy Policy impact decisions about granting wind farm licences?
The Scottish Government has a target to generate the equivalent of 50% of Scotland’s overall energy consumption (which includes electricity, heat and transport combined) from renewable resources by 2030 and fully decarbonise the energy system by 2045. Offshore wind expansion is at the heart of this strategy, and as a result there is heavy investment in wind energy and multiple wind farm licences are being granted to achieve these targets.
The issue with this is that energy targets are based on the amount of renewable energy generated as a percentage of consumption – not on the amount of “green” energy actually used.
This distinction is important.
Scotland frequently generates more renewable electricity than it consumes annually and large amounts of this renewable energy are already curtailed, creating constraint payments.
Building more wind farms will fulfil a pledge in the Scottish Government’s policy in the short term. In the longer term grid and storage facilities need to be vastly improved BEFORE more ‘potential’ is added to the system.
However, new wind farms will fulfil the pledge, and it’s relatively quick and easy to do by granting licences to operators such as Scottish Power Renewables. The Scottish Government didn’t promise to connect all this extra power to the creaking and overloaded grid…they just promised to produce it….and this is where its policy fails.
NatureScot, the Scottish Government’s own nature conservation experts and a statutory consultee for wind farm development has stated that “The transition to renewable energy is essential, but it must be done responsibly, and not at the expense of environmental safeguards that exist to protect some of Scotland’s wildlife”.
What research is there regarding impacts versus benefits for Scotland’s coastal communities?
University of Aberdeen and other UK academics have examined the social, economic and distributions impacts of offshore wind on coastal communities and found:
- Coastal communities often bear the impacts while benefits are widely dispersed (effects on visual amenity, tourism, recreation, fishing and community identity are lost whilst electricity and wider economic benefits are distributed internationally).
- Community benefit arrangements are often small, inconsistent and not directly linked to the scale of local impact. Scottish Power Renewables has specifically stated that they will not provide details of community benefits until after the licence for MachairWind has been granted.
- Human and community impacts are under-researched, including community identity and sense of place, industrialisation of the seascape, tourism perceptions, housing and infrastructure pressures and effects on fisheries and marine industries.
What can we do about this?
Until the folly of this short-term thinking is acknowledged, we’ll continue to get more potential electricity which can’t be used, and more applications for wind farms in Scotland’s most beautiful and fragile inland waters.
We need to lobby our local councils and Scottish Government via MSPs and those responsible for decisions relating to energy in Scotland to persuade them to pause approval for new wind farm licences in Scotland until a better strategy can be found.
Responsibility for energy in Scotland is split between the Scottish Government and UK Government and is a mix of devolved and reserved powers. You can express your concerns to:
Gillian Martin MSP – Scottish Government Cabinet Secretary for Climate Action and Energy – Gillian.Martin.msp@parliament.scot
Michael Shanks MP – UK Government Minister of State for Energy – michael.shanks.mp@parliament.uk
Sources:
RenewableUK – a UK trade association for the renewable energy industry, representing circa 500 member companies spanning the wind, wave, tidal, and green hydrogen supply chains.
Tim Harper – Deep Tech Advisor and Energy Transition Consultant
Figures from Octopus Energy – Wasted Wind Tracker
More Reading:
https://www.renewableuk.com/news-and-resources/blog/an-overview-of-constraint-payments/
https://wastedwind.energy/2025-07-04