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- The Herald Scotland
Does Scotland need more onshore windfarms? The data
But is this true? And what would it mean to have too much onshore wind? The claims are examined here, as well as key issues like constraint payments and why so many of the UK's onshore wind farms are in Scotland.
Claim: Scotland is already producing more electricity than it needs
Yes. Electricity transfers data show that Scotland exported 21.0 TWh of electricity and imported 1.3 TWh of electricity in 2024. This means that Scotland's net exports of electricity (exports minus imports) in 2024 was 19.7 TWh. This is around half the electricity generated in Scotland that year.
Claim: Scotland already has enough onshore wind capacity to meet its total electricity 2050 demand.
Currently, according to DESNZ, Scotland has an onshore wind capacity of 10GW, and a gross peak demand of 4GW. However, NESO, in its Ten Year Statement estimates gross peak demand for Scotland in 2050 at between 8.5GW and 11GW depending on what degree of electrification takes place.
'Over the next 10 years,' it says, 'rapid growth in renewable -generated electricity in Scotland will mainly be attributed to offshore wind. This will cause far greater power transfer requirements across the Scottish boundaries, increasing the network reinforcement needs in some areas. Generation capacity in Scotland heavily exceeds demand, thus Scotland will be expected to export power into the rest of Great Britain most of the time except during periods of prolonged low wind, where the reverse may occur.'
Graph of Scotland's gross electricity demand from NESO's Ten Year Statement (Image: NESO)
However, in a renewables system, where generation is intermittent, capacity needs to be significantly higher than peak demand, so capacity will need to be far higher than that 11GW, and we would not already have double.
Since there are, as yet, no target figures for Scotland's wind generation for 2050 – though overall, according to the Climate Change Committee's Seventh Carbon Budget, UK is aiming for 125GW offshore wind, 27GW onshore wind and 106GW solar – it's hard to know by how much Scotland is likely to exceed its own demand.
Claim: Scotland already has enough wind consented and in planning for 2030 or 2035
One Caithness-based campaigner who has looked at the figures, is architect Kathrin Haltiner, who says, 'For the whole of Scotland for 2030 and even to 2035, what is already in the planning system, without any scoping applications, is more than enough to reach these caps and these caps are important because anything that goes over these caps is not going to help with net zero.'
Using figures derived from totalling up projects listed in the UK government's Renewable Energy Planning Database, she finds that across the whole of Scotland there is now 9.4GW worth of projects listed as operational.
Haltiner's already installed figure is a little different from those quoted by DESNZ, at the end of last year Scotland, which said Scotland had installed onshore wind capacity of 10.3GW, and from a figure of 10.9GW given to me by Scottish Renewables - but not dramatically so.
She also calculates that across Scotland 6.8GW are consented to and under construction, plus an addition 8.1GW in the planning process, making a total of 14.9GW in the pipeline, making 24.3GW in total.
How does this compare with the cap for Scotland for electricity generation for 2030?
The Clean Energy Action Plan, in its update on its annex, states that Scotland, as whole, has a cap for electricity generation for 2030 of 20.5GW - over 10GW more than the capacity have now. But are we nevertheless, as Kathrin Haltiner, suggests already in danger of exceeding it?
Following Haltiner's calculations, the sum total of all the onshore wind projects that are operational, in construction, consented to and in the planning system is would be 3.8GW more than the cap.
But what is hard to estimate is how many of these projects would fall by the wayside, due to failure to get consent, economic reasons or other factors, as many windfarm plans have done in the past.
Another way of looking at it is that, across Scotland, we only have that 3.8GW still to take up, and given that there is twice that sum capacity (8.1GW) in projects sitting in the REPD planning system not all of those can happen.
Of course, in any case not all will happen. Some will be withdrawn, some projects will be abandoned, others reduced, and some, even from the list of projects awaiting construction may not even happen. Others may not happen within the timeframe.
Does that mean we are set to have too much onshore wind for current caps? No, but in the unlikely event that every project that is sitting in planning were to be built Scotland would significantly exceed its cap. These figures suggest that only half of these projects can happen.
Is this a reason to slow down?
Not according to Scottish Renewables. Their director of onshore, Morag Watson, put it this way, with different but similar figures and arguing for continued urgency.
'Scotland has to increase its onshore wind capacity from 10.9GW to 20GW in about five years. In Scotland at the moment in the pipeline of projects that are consented but not yet built, we have 7.5 GW. So we need everything in the pipeline and 2 GW more. So this idea we have too much wind already is just not borne out by the strategic plans.'
She also points out that the process of going through scoping, planning and constructing a wind farm can be long. 'Viking windfarm on Shetland, that was a 15 year process to make the needs case for that. Renewable projects can wait up to ten years for a grid connection and you only get a connection to the grid when it's needed.'
'A project can go through the planning system, but just because they have planning permission doesn't mean they are about to get built and connected to the grid. Post planning they'll get a grid connection date and they will work to that grid connection date as to when they start building.'
Mostly Watson notes, the strategy up till 2030 is about reducing our dependency on gas, which is not only responsible for significant carbon emissions, but also, through its high price, drives up electricity bills. By 2030, the goal is to reduce the amount of gas used to generate electricity down to about 5% on the system.
She says: 'At the moment it's about taking the gas and other fossil fuel generation off the system – replacing it with renewables because they are cheaper and more reliable in terms of pricings that you pay. '
Is there also enough in the pipeline for 2035?
'Post 2030,' Morag Watson explains, 'what we start to see is the electrification of transport and heat really accelerating. That's when you see electricity demand really grow."
The next milestone and cap along the way is 2035, and what's striking is how little more capacity – just 700MW – is being allocated to Scotland over that period, suggesting that the expansion needs to be at least a scale of ten less over those years.
Scotland's offshore wind industry has already flagged that up as a problem. A group of 13 developers signed an open letter to UK Energy Secretary Ed Miliband amid concerns of a 'de-facto ban' on Scottish onshore wind post-2030.
Earlier this year a group of onshore wind developers in the letter, they stated: 'Currently, the cap in the Plan will allow only 700MW of additional Scottish onshore wind capacity to connect between 2031 and 2035.
'This would result in a decrease in the rate of installations allowed after 2030 of over 90%, and amounts to a de-facto ban on Scottish onshore wind post-2030.
Claim: Scotland is already doing more than its fair share of onshore wind
Last year, Scotland, according to RenewablesUK, was operating 63% of the UK's onshore wind capacity. By 2030 Scotland will be producing 20.5GW of power, well over two thirds of the onshore wind generation in the UK, which is set at 27-29GW.
As this map shows, Scotland is doing a lot of the heavy lifting when it comes to onshore wind. Partly this is because previously England had a de facto ban on onshore wind developments.
But there are, as Morag Watson told me, other factors that feed in to why Scotland, in any case, is getting most of the wind. 'The reason for this," she says, "is you can only put onshore wind where the wind consistently blows at 7ms or faster and there are chunks of England where that doesn't happen. You cannot build a wind turbine within 800m of someone's home, or with the bigger turbines, within 1km of someone's home.
"So if you take a map of the UK and take out everywhere where the wind is less than 7 m/s and then take out everywhere where you're within 800 m of someone's home, and then remove National Parks and national scenic areas, where you also cannot build wind, and again is why you don't see onshore wind predominantly down the west coast an central of Scotland, the only places you can build onshore wind are these parts of Scotland and mid Wales. This is why Scotland does do the heavy lifting on onshore wind.'
But, she notes, England is doing most of the heavy lifting on solar. Unsurprisingly, the south of England, where the sun is stronger, is also where there are more solar developments.
Claim: Constraint payments are already costing millions and only going to rise – suggesting there is already too much onshore wind
Often windfarm critics point out the huge cost of constraint payments, made to renewable energy generators to compensate them for reducing their electricity output when the grid cannot handle the full amount of power being generated.
A report published earlier this year by the Renewable Energy Foundation found that wind farm constraints continue to rise, both in total volume and in cost. In 2024 the consumer paid more than £393 million in direct costs to discard 8.3 TWh of wind energy, a rise from the previous year's cost of £310 million.
"Planning application data," the report said, 'shows that the, in our view, indefensibly high rewards for constraints continue to incentivise wind farm development in areas of the UK that have low demand and weak grid connection, resulting in high constraints.
More than 98% of the total constrained volume, it noted, arises from Scottish wind farms.
However, by far the biggest constraints were applied not to onshore wind, but offshore wind, including Seagreen.
'In particular, the offshore wind farm, Seagreen, whose majority owner is SSE, was alone responsible for 40% of the total volume of constraints. Seagreen is currently unsubsidised but 25% of its capacity has been awarded an as yet unimplemented Contract for Difference (CfD).'
The most constrained onshore windfarms were Viking (Shetland), Dorenell (Moray), which is currently proposing an extension which would make the area home to the largest onshore array of turbines, Stronelairg (Fort Augustus), which claims to be on of Scotland's windiest windfarms, Bhlaraidh (Glenmoriston). Of these four, all but Dorenell are owned by SSE Renewables.
But, Morag Watson points out that, relative to other impacts on electricity bills, like the fact gas prices set electricity prices 98% of the time in the UK (which has the highest electricity prices in Europe), the cost of curtailment is not that big.
'If you look," she says, "at the cost of balancing the grid in the average electricity bill, which according to Ofgem is £929, £32 of that is the balancing, just under 3.5% and of that only part of that would be the cost of constraint payments. That's a vanishingly small part of your electricity bill. About £352 of your bill is driven by the wholesale cost of electricity – and that is driven by the gas price. So getting rid of the constraints and getting that gas down would be a really great thing for all of us.'
Part of what is driving constraints is the pinch point around what's called the B6 boundary in the grid between Scotland and England, which has a transfer capability currently of around 6.7 GW. But it isn't the only problem. Arguably the B4 boundary, between the North of Scotland and South of Scotland transmission areas, which has a capacity of only 3.4GW is still more important.
A recent blog published by UK Energy Research Centre, written by Professor Keith Bell and Callum MacIver of the University of Strathclyde looked at the 'impact of the role of transmission system availability (or rather unavailability) on rising curtailment costs in Britain'.
They noted the importance of the B4 boundary. 'Lots of the wind in Scotland is located in the far North, including all of that new capacity from Seagreen, Viking and Moray East, totalling around 2.5 GW. The B4 boundary is therefore often the primary pinch point on the system.'
The blog examines the impact of the failure to as yet build planned grid enhancement, especially the Peterhead to Drax undersea cable, which the system operator originally gave a delivery date of 2023, but is now not due till 2029.
'It seems clear we haven't built out enough North to South transmission capacity quickly enough, and that lies at the root of our current issues… but is there more to the story?'
It goes on to point out that an additional issue is that 'often, the real-time capacity on the B4 and B6 boundaries is well below the maximum level, often even below 50%".
The authors note also note that even these boundaries are not working to capacity. 'Not only have we, up to now, failed to add a 2 GW link across the congested Scottish boundaries, but B4 spent more than half of 2024 with an additional equivalent scale 2 GW reduction in operating capacity.'
The reason for this? 'Ironically,' they write, 'it is due to the implementation of network upgrades'.
MacIver also looked at what the effect of additional network capacity across the B4 and B6 boundaries would have been and found that 'even a modest increase' across these boundaries of 500MW could have resulted in 'reduced curtailment costs by as much as 25% from the £1.65bn total in the 15 month period from the start of 2024 to the end of April 2025'.
He also found that if there had been 'a 2000MW uplift, in line with delivering the Peterhead Eastern Link project to its original schedule of 2023, then a full 73% of the thermal constraint costs could potentially have been avoided'.
Overall, therefore, the constraint problem is an argument for more grid enhancement, particularly the development of undersea links, rather than less windfarms.
