ONSHORE wind is a well-established part of Scotland’s energy system and landscape – as of March this year, there were nearly 5000 wind turbines in Scotland; another 2600 are either under construction or awaiting construction.
But, according to Zero Waste Scotland, more than 5000 wind turbines in Scotland will need to be decommissioned in the next 25 years as they reach the end of their useful lives. Most wind farms operate for 25 to 30 years; so what happens to them after that?
Burgar Hill Wind Farm, in the north of the Orkney Mainland, is approaching this end-of-life phase. The six turbines that currently sit on the land are between 16 and 25 years old, but Burgar Hill has hosted wind turbines for far longer.
As a testing site in the 1980s, Burgar Hill was home to some of the country’s first wind turbines. Now, resident and landowner Melissa Spence is making plans with Thrive Renewables to repower the wind farm – a move which not only extends its life but could dramatically increase its power output.
The opportunity: Doubling onshore wind capacity without using any more land
REPOWERING, in essence, is replacing old wind turbines with new ones; the alternative would be to fully decommission a wind farm and return the land to its previous state. Thanks to improvements in turbine technology, repowering a wind farm with like-for-like replacements can increase the electricity generated by 10-20%.
Due to the increasing scale of wind turbines over the last 25 years, repowering with larger turbines can more than double a wind farm’s electricity output. On Burgar Hill, Spence’s plans to replace five 100m turbines with five 149.9m turbines would increase the capacity of this small wind farm from 11MW to nearly 30MW.
Scotland’s first commercial wind farm, Hagshaw Hill, was repowered between 2023 and 2025. The 26 small turbines were replaced with 14 large ones – multiplying the power output by five times.
Thrive Renewables, which is working with Burgar Hill Renewables Plc on the repowering bid, estimates that the UK’s onshore wind capacity could be doubled if every wind turbine was upgraded. This would surpass Westminster wind energy targets, without any increase in the land area covered by wind turbines.
The challenge: how do you recycle renewables?
REPOWERING is less land-intensive and resource-intensive than building brand-new wind farms; at Burgar Hill much of the infrastructure and access roads from the existing wind turbines can be reused or adapted.
However, the turbines themselves, and their foundations, will have to be fully replaced. What happens to the old turbines?
Fortunately, 85% to 95% of a wind turbine is recyclable. Zero Waste Scotland estimates that recycling all of the decommissioned wind turbines in Scotland between 2025 and 2050 could produce more than 1 million tonnes of steel, 136,000 tonnes of iron, and 22,000 tonnes of copper, as well as other materials.
Based on scrap metal value alone, this would be worth £200 million to the Scottish economy.
More difficult to deal with are wind turbines’ fibreglass blades. In recent years, 100% recyclable turbine blades have been developed, but in older wind turbines these components are the most difficult to recycle.
However, Kenny Taylor, partner (energy infrastructure) at Zero Waste Scotland said there are “a number of examples which highlight the existing pioneering activity advancing the circular economy in the Scottish wind industry”.
First, wind turbines are being repaired and retrofitted to extend their working lives before repowering is needed. Lochgilphead-based company Renewable Parts refurbishes and remanufactures wind turbine parts to extend their lives and reduce waste in the wind turbine life cycle.
One of the turbines at Burgar Hill has already been refurbished – after 22 years in one of the UK’s windiest spots, the turbine has been able to carry on thanks to second-hand blades from a turbine in relatively windless Bavaria.
When turbine blades eventually need to be fully disposed of, there are several innovative options. The old blades from the Sigurd turbine on Burgar Hill were turned into bus shelters and e-car charging shelters. The turbine blades from Hagshaw Hill were converted into a polymer which can replace traditional construction materials by Belfast company Plaswire.
Scottish company Reblade has also designed a construction material which is made from 45-50% shredded wind turbine blades – as the number of decommissioned wind turbines increases faster than the demand for new bus shelters, scalable solutions like this are vital to addressing the scale of Scotland’s wind decommissioning challenge.
There is no specific obligation for energy operators to recycle wind turbine blades, nor is there publicly available data on how many of Scotland’s decommissioned wind turbines are being recycled.
Taylor is clear that the industry must be prepared to scale up these few promising recycling examples as a whole generation of Scottish wind farms come to the end of their life.
“It is … essential that the wind industry, supply chain and government are suitably prepared to capture the maximum possible value from wind decommissioning activity before more of Scotland’s wind assets reach the stage of decommissioning,” he said.
Communities: Continued opposition and new opportunities
REPOWERED wind farms could end up looking very different to their current incarnations, even if they cover the same area of land. Burgar Hill Renewables and Thrive plan to place new wind turbines as close as possible to the old turbines, with roughly a 50% increase in the height of the new turbines.
But at Crystal Rig Wind Farm in East Lothian, Fred Olsen Renewables has proposed to replace 25 100m turbines with 10 200-230m turbines – undoubtedly a very different feature on the landscape.
In this context, it is understandable that repowering is not an automatic process – operators must submit a planning application for the repowering, including lengthy consultation with statutory bodies and local communities.
The dramatic changes to Crystal Rig have been opposed by East Lothian Council, and local community groups have said that the wind farm should be dismantled and returned to its original state as had been promised when the wind farm was built.
In Orkney, the community reaction to the Burgar Hill repowering bid has been more positive.
“There are still people who are not enormous supporters,” said Spence. “But I would say that generally the community is really supportive of the site continuing to operate. Everybody in Orkney is quite used to there being turbines there, and I think as long as we do it in a considered manner, we’ll maintain general support.”
Matthew Clayton, CEO of Thrive Renewables, which has undertaken repowering projects elsewhere, says that in general, the discussion with communities is easier the second time round.
“If you really drill down into a lot of the opposition to any planning concern, a lot of it comes from uncertainty … a lot of those bridges are already crossed with the repowering,” he said.
Repowering might also provide a second chance for communities to negotiate a better deal with renewables companies. Wind farms usually pay a community benefit fund, which is recommended to be at £5000 per MW of energy capacity – so repowering should automatically increase the size of community benefit. The Hagshaw Hill community benefit fund increased by an eye-watering 2500% after repowering.
The Scottish Government has repeatedly expressed ambitions to encourage shared ownership of onshore wind between developers and communities, which would allow communities to receive a percentage of wind farm income rather than a fixed rate.
As of October last year, only 1.3% of onshore wind in Scotland was under any kind of community ownership, but the consultation and planning processes involved in repowering could offer communities a second chance at shared or full community ownership.
For example, Forestry and Land Scotland (FLS), formerly the Forestry Commission, hosts 27 operational wind farms on its land; 10 of which are due for repowering soon. FLS is trialling a new approach which gives communities more opportunity to obtain a community asset transfer of the wind farms when they are repowered. While the first repowering will not be due for a few years, FLS is already in conversation with the communities around Black Law in South Lanarkshire and An Suidhe in Argyll.
Burgar Hill Renewables will be offering a 10% ownership share to the local community if its repowering application is accepted.
The bottleneck that could stunt the potential of repowering
ONE of the key barriers to unlocking Scotland’s renewables capacity and transitioning to net zero is the National Grid. Our electricity network is desperately struggling to keep pace with the expansion in demand and supply of electricity. Without a higher capacity grid connection, wind farm operators looking at repowering will not be able to use more powerful turbines and increase their energy output.
IN an effort to catch up, the system for organising new grid connections has recently been reviewed. Until recently, new grid connections were delivered on a first-come, first-served basis, meaning developers without planning permission could sit ahead of ready-to-build, consented projects for years on end.
This system has now been overhauled to prioritise grid connections for projects which are further along in the planning process, and those which are close to energy demand centres.
Although Scottish government policy encourages repowering of existing wind farms, no specific prioritisation has been given to repowering in the grid reform process. This means that Burgar Hill Renewables, which has just submitted its planning application for repowering, has lost its previous offer of a grid upgrade to accommodate the increased capacity of the new turbines, while new wind farms in Orkney, which have planning permission have received grid offers.
“Within that planning and recalibration process, it looks like the repowering element hasn’t really been factored in … It feels like a bit of a miss not to have factored in the repowering demand into that national landscape in the [same] way that the existing demand or the existing use of grid was factored in,” said Clayton from Thrive.
In the worst-case scenario, if no grid offer is awarded, Burgar Hill Renewables would be forced to scale down the repowering to something that the existing grid connection can handle. If planning is awarded but the grid connection is delayed, they may be able to start replacing turbines gradually. This gradual build scenario could delay the full repowering by up to five years, and extend the period of disruptive construction for local communities.
“It feels like we’ve got a wind farm here that is in one of the windiest locations in the country, in Europe perhaps, and successful turbines there for 40-something years. It should be the right place to continue operating a wind farm, because of its proven ability, because of the fact that we can repower and not have as much of an environmental impact as if we were starting from scratch. [But] it feels hard from a grid perspective … overall the planning policy and the grid reform make sense, but what it feels like we’re experiencing is the reality of those is not quite matching the theory of the support behind repowering,” says Spence.
A spokesperson from National Energy System Operator (NESO) said: “Connections reform replaces an outdated first‑come, first‑served system with a pipeline of projects that are ready to build and aligned with Great Britain’s energy needs. This is a fundamental shift that will help deliver a system that is reliable, clean and affordable, while reducing delays and avoiding unnecessary costs for consumers.
“We have recently consulted on repowering as part of our continuous review of the connections reform process and are reviewing the responses we have received.”
Low-hanging fruit
WHILE there are no true silver bullets in the real world, repowering does offer some relatively easy wins for Scotland’s energy transition. The opportunity to increase our energy output just through the natural life cycle of wind farms, rather than through designing, locating and planning brand new wind farms, is not to be sniffed at. However, the challenges that repowering poses, from long delays for grid connections to tricky waste management to the eternal local opposition to onshore wind, are not insignificant either.
