Imagine you have just built yourself a lovely new house with an unobstructed view of some nearby mountains. But, within months, someone else starts building a home right in front of yours, blocking your view. A neighbourhood dispute looks inevitable.
A similar scenario is playing out across northern Europe with the rapid development of new offshore wind farms. As the seabed becomes increasingly crowded with new turbines, developers are becoming concerned that new wind farms could âstealâ wind from existing sites.
The problem lies with wind farm wakes. âThe job of a turbine is to rotate a set of blades that extract energy from the incoming wind. But, as you extract that energy, then you leave behind much lower energy,â says at the University of Manchester, UK. That creates a region of âlow-velocity windâ, he says, which can extend for tens of kilometres.
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The issue has become critical as more offshore wind farms have sprung up and turbines have become larger and more powerful, creating bigger wakes. At least a dozen disputes have broken out among clean-energy developers in the UK as they jostle to protect their wind resources from neighbouring projects, according to , who previously led General Electricâs offshore wind business.
âWake effects are nothing new. Itâs been there since the very beginning of wind farm development,â says Sheikh. âWhat has changed over the last few years has been the rapid scale of the growth in the size of wind turbines.â
Estimates of the financial impact of wake losses vary. published last year by a team at the University of Bergen in Norway suggests wind farm wakes can extend up to 50 kilometres and cut wind resources available to downstream farms by as much as 20 per cent. from researchers in the US suggest wakes could affect yields by more than 30 per cent in certain severe conditions.
Most in the wind industry that wakes can cut the yield of nearby wind farms by . âThe big numbers are, in the main, taking an extreme, specific scenario,â says at UK consultancy K2 Management, which conducts energy yield analysis for wind developers.
But even yield losses of a few per cent can have a huge impact on an industry working within increasingly tight margins. âThis is something that is a worry, especially from an investment point of view and profitability of existing or future projects,â says Ouro. Ultimately, financial uncertainty and reduced profitability could result in increased power prices and reduced capacity.
In the UK, the government wants to dramatically increase offshore wind power to make it the backbone of the countryâs future clean power grid. It has set a target to increase capacity from the 15 gigawatts currently in operation today to 43 to 50 gigawatts by the end of the decade.
Accurately assessing the impact of wake effects is therefore crucial for the UKâs climate goals, says Ouro. âNet zero is not about how much capacity, how many gigawatts we install. It is how many gigawatt hours [of electricity] we can produce.â
Last month, the University of Manchester launched a national assessment to try to quantify the problem for UK developments. Ouro is leading the 12-month project, which will work with offshore wind developers to model how wind farms set to be operational in 2030 will affect the yields of those currently generating electricity. It will be the first assessment of its kind in UK waters.
âThe biggest outcome is that we can inform the future lease sites⌠so we can reduce the wake effects,â says Ouro. That might mean tweaking the boundaries of wind farm sites to include larger âbuffer zonesâ between neighbouring farms, for example, or changing the orientation of sites to reduce the wake effect. âIf we were to provide information on where to put future turbines, if we improved that a bit, that would be a huge success, because that is a benefit for taxpayers and everyone,â says Ouro.
But planners must strike a balance between maximising power output from UK waters and ensuring the country remains attractive to offshore developers. Other nations are encountering the same issues and watching the UKâs response closely. âThis is not just a North Sea issue. This is very much an international issue,â says at Norwegian law firm Wikborg Rein.
In the meantime, firms with sites already in development or under construction are battling it out in the planning and legal systems to protect their wind resources. Some are establishing âwind wake agreementsâ that might include compensation for affected wind farms, as well as agreements to design new sites to minimise downstream impacts.
Yet despite the concern over wind wakes, the UK remains a world-leading market for offshore wind developers, helped along by. For many developers, that is worth risking some trouble with the neighbours.
