We have been puzzled in our reports by the underperformance of wind generation in recent months, in particular in the EU zone. After a period of strong growth in both capacity (GW) and generation (TWh) during 2010-2022, wind generation in the EU bloc has disconnected with the growth in capacity.

In fact Germany, which is the largest EU country in terms of wind generation, has seen its actual wind generation decrease over the last two years, from its peak of 139.9TWh in 2023 (to 137.5TWh in 2024 and 132.4TWh in 2025). Meanwhile wind capacity increased from 69.1GW in 2023 to 70.8GW in 2024 and we estimate 72-73GW in 2025.

True, the pace of additional capacity has significantly decreased from +3GW to +5GW per annum during 2010-20 and the weather conditions might have changed with lower wind than usual.

But at a EU+ UK level, our colleagues from Volue Data & Forecasts calculate that in 2025, wind generation underperformed by a significant 120TWh vs. what could have been expected based on capacity and normal weather conditions. The under-performance was mainly noticeable during the winter months.

Another reason could be the so-called “wake effect”.

This occurs in wind turbines when some of the energy from the wind is extracted by initial turbines, reducing the energy available to the turbines behind it.

Wind both slows down and becomes more turbulent after it passes through a turbine, which also increases the risk of fatigue damage for downstream turbines.

Research from the University of Colorado has found that the wake effect is stronger offshore. The research predicts that adding more wind turbines in the Atlantic Ocean could reduce the output of existing wind farms by more than 30%.

Most of the reduction comes from wakes formed between turbines within a single farm, but wakes can reach turbines as far as 55km away, so affect other wind farms. The research found that in hot summer periods (when electricity demand is high) wakes last for longer time periods and over longer distances.

There were similar findings in a 2025 study commissioned by the Dutch government, which found overall losses from the wake effect of 21.7%. The Netherlands is aiming to increase installed wind capacity from 5GW now to 70 GW by 2050.

Separate research by Belgian academics found that the effect of adding more wind farms in the North Sea would reduce the annual energy production of 25 out of 69 currently operational wind farms by over 5%, with 13 of them having reductions of more than 10%. The planned Princess Elisabeth zone in Belgian waters is predicted to reduce the output of existing Belgian wind farms by more than 15% in one out of every five 24-hour periods with high production potential.

There are possible workarounds for developers, one of the most obvious being to manage the spacing between turbines. That is obviously easier in the US, for example, than in Europe, due to greater availability of space, but the Trump administration has shown its hostility to wind turbines, often called “wind mills” by Trump.

Co-operation between wind farm operators in neighbouring states will be needed to maximise their efficiency. If such co-operation is lacking, those counting on a rapid acceleration of wind generation capacity are likely to be disappointed.

Wind power also creates its own environmental challenges which will need to be addressed. By 2040, between 10,000 and 20,000 turbine blades will be retired each year in Europe alone. Globally, there will be about 43mt of cumulative blade waste by 2050, and permanent disposal solutions need to be found.

I look forward to meeting you at E World in Essen on 10-11 February on the Volue Data & Forecasts stand (Halle 3).

Guillaume Perret