As wind farms in the North Sea continue to expand, governments and developers must take into account the so-called wake effect. The construction of new wind farms reduces the efficiency of existing ones, with estimated energy losses exceeding ten percent in some cases. This is the conclusion of a new study conducted by KU Leuven researchers from the Department of Earth and Environmental Sciences and the Department of Mechanical Engineering.
At the 2023 North Sea Summit, nine European countries agreed to expand offshore wind capacity to at least 120 GW by 2030 and 300 GW by 2050. This planned expansion is a key element in the energy transition and European climate goals.
A new study by KU Leuven scientists, published in Environmental Research Letters, gives a clear indication of the current and future energy output of wind farms in the North Sea. The model simulations show that the average electricity production of wind farms—expressed as a share of their maximum capacity—will be 1.6 percentage points higher in 2030 than that of the current generation of wind farms. This increase is due to the use of more powerful and efficient turbines and further development of wind farms in favourable locations.
Energy loss due to ‘wake effect’
On the other hand, the planned expansion also leads to increased competition between wind farms, known as the ‘wake effect’ or ‘wind shadow’. ‘To generate electricity, wind turbines extract kinetic energy from the air, causing it to move slower,’ explains Ruben Borgers, postdoctoral researcher and lead author of the study. ‘New wind farms that were built upwind of existing installations reduce wind speed in the downwind farms, resulting in lower electricity production and reduced profits.’
These findings should not hinder the further development of wind farms in the North Sea, as it plays a vital role in the transition to a carbon-neutral society. While further validation studies are required, the results do highlight the need for better coordination and more international cooperation.
Professor Nicole Van Lipzig
The simulation shows that 13 of the 69 wind farms currently built in the North Sea could experience energy losses of more than 10 percent by 2030. In exceptional cases, losses may exceed 18 percent. Belgium and Germany appear particularly vulnerable to the effects of ‘wind shadow’ due to their limited maritime area.
Better coordination and more cooperation
‘With this study, we provide greater clarity on the impact of the wake effect. It is crucial to consider this in future projects, especially in the context of projected yields and financial feasibility,’ says Professor Nicole van Lipzig. ‘These findings should not hinder the further development of wind farms in the North Sea, as it plays a vital role in the transition to a carbon-neutral society. While further validation studies are required, the results do highlight the need for better coordination and more international cooperation. Only then will it be possible to achieve the goal of 300 GW of wind capacity in the Northern European seas by 2050 in a sustainable an efficient way.’
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