Developers will not have to pay out for 'wind theft' under new draft UK policy

Developers will not have to compensate for wake losses their new offshore wind projects cause incumbents under draft UK policy – an issue Orsted, RWE and TotalEnergies are among those currently clashing over.

The Department for Energy Security and Net Zero (DESNZ) last week launched a consultation on revised energy National Policy Statements (NPS) that support decisions on major energy infrastructure in the UK.

The NPS provide the legal framework for planning decisions and were last updated in January 2024.

As part of a consultation running until late May, DESNZ published draft updates to the NPS, including on the issue of inter-farm wind wakes, which it noted has “gained attention” as more offshore wind projects are developed in British waters.

Germany’s RWE and France’s TotalEnergies are meanwhile among the developers currently seeking to secure approval for huge new offshore wind projects and arguing against such measures being required under UK law.

The only decision issued on this issue to date came in 2023, when RWE’s Irish Sea Awel y Mor was ordered to mitigate the wake loss effects on a neighbouring site – a decision extensively cited and fought over in ongoing planning proceedings.

In the draft NPS, however, the government appears minded to move in a different direction to that earlier decision.

On wake effects, not addressed in the previous NPS, it said offshore wind developers should “consider the impact of their proposal on other activities and make reasonable endeavours to address these.”

“At the design stage there are therefore clear merits for applicants to make an assessment of inter-array wake effects between their proposed developments, and nearby offshore wind generating stations that are planned, consented or operational.”

Developers must show they have “taken all reasonable steps to minimise as far as possible the impact of wake effects” on nearby assets, it says.

Crucially, however, it said there is “no expectation that wake effects can be wholly removed between developments, or that inter-project compensation arrangements are a necessary means to mitigate the impact of wake effects, although developers may opt to take such approaches outside of the planning process.”

Given developers are currently fighting tooth and nail in planning proceedings over whether they should have to pay compensation to existing projects, it appears somewhat fanciful that they may “opt” to do so in the future.

The draft NPS state that where a developer can show they have assessed wake effects, “taken all reasonable steps to minimise as far as possible" their impact and shown that they have made "reasonable efforts to work collaboratively with those who may potentially be impacted, then the existence of a residual wake effect impact is unlikely to carry more than limited weight against a project in the planning process.”

'All mitigation methods lead to net loss in generation'

The draft NPS now therefore appear to place more emphasis on mitigation rather than compensation of wake losses – but the efficacy of this approach remains doubtful.

Kester Gunn, chief scientist at RWE Renewables, wrote in a recent blog post that full wake mitigation between wind farms “is not possible.”

One approach to mitigation could be powering down turbines at one site to allow more wind to pass through to the next. But Gunn said that all modelling shows this would result in an overall decrease in generation, as not all wind that passes through one wind farm will be captured by the next.

The results are “even worse” if a developer mitigates by changing the layout of one wind farm, he said. “The mitigating farm is forced to position its turbines sub-optimally, squashing them closer together. This results in less generation not only when the wake is hitting the other farm, but for all directions. For every wind condition – not just the rare ones where wakes are a problem – the farm generates less energy.”

“The loss seen by the first farm will outweigh the gain at the second wind farm by orders of magnitude – and result in an overall net loss of output from both combined, compared to if mitigation had not been pursued.”

As far as RWE is aware, Gunn said that “no method of mitigation modelled by independent academics or developers has been able to mitigate more than a small percentage of the wake impacts” and “all wake mitigation methods investigated to date lead to a net loss in generation.”

That will undoubtedly be difficult, however, given the scale of wake losses that are now being modelled, unpredictability over where new projects may be built a decade or more after an earlier asset is completed, and the vast distances that wind wakes can extend.

Developers will find themselves 'swapping shoes' over issue

Derek McCulloch, a partner and head of energy at Gillespie Macandrew who has worked on wake loss matters, said that, globally, there is “no standard approach to compensating for wake effects.”

“Generally, wake loss compensation is by agreement and such agreements tend to depend on leverage of the first developer over the second, for example in consenting and other licensing objections”.

Policy that favours designing offshore wind farms to mitigate against wake effects is “one approach but not a complete answer,” he said, adding that developers are likely to prefer compensation over mitigation in any case.

McCulloch expects “strong views submitted” in the NPS consultation, noting that maximising effective energy generation in the public interest “may mean compromises”.

Larger developers will have an interest in maximising the output of both current and future wind farms, he said, meaning they will be “occasionally swapping shoes from one foot to another.”