From KlimaNachrichten Redakteur

We can see from the Tagesschau that a huge expansion of wind power plants is planned off Belgium.

“The Belgian authorities want to triple the output by 2030. Then every household in the country should be able to get wind power from the North Sea. An artificial island – 45 kilometres off the Belgian coast – is to connect offshore wind farms to the high-voltage grid on land – and to the lines of the neighbours. After all, the hunger for clean energy is growing throughout Europe. By the middle of the century, the continent aims to generate more than 300 GW of North Sea wind. 

Belgium’s Prime Minister de Croo will discuss how this is supposed to work today in Ostend with the heads of state and government from seven other North Sea countries and Luxembourg: “For us, this summit is not about formulating ambitious goals. We have enough of that. For us, the importance of this summit is to speed up the execution.” According to the host, governments need to better coordinate construction plans and permitting procedures. So far, according to de Croo, everyone has done it for themselves – with the result that in some years nothing is progressing at all, while in others there are so many tenders that the industry can’t keep up.” 

An article in ESKP (Earth System Knowledge Platform), the Helmholtz Institute’s knowledge platform Earth and Environment, fits in with these plans. Whoever reads the report must admire the scientists who wrote it. Again and again, they have well-founded concerns that the expansion of wind power in the North Sea will also have undesirable side effects, but they don’t really want to say it. The danger of being seen as an obstacle seems to be too great.

“Here, the focus will be on the physical aspects: wind turbines and entire wind farms influence atmospheric and oceanic processes. Turbulence and wake vortices occur in the surrounding air and seawater. Questions here are, for example: What effects do wake vortices have on the environment and what role do possible interactions between individual wind turbines that stand together in a cluster play? How do wind farms influence each other and how do they possibly affect the local climate? And last but not least: How do atmospheric and oceanic processes interact with each other? Due to the intensive expansion, it is necessary, but also possible, to investigate these effects directly on site. The dynamics are extremely complex and are influenced by various factors in the atmosphere, but also by properties of the water surface. 

The wind yield can be reduced by wake vortices in the lee of wind turbines and wind farms (“windward” = side facing the wind, “leeward” = side facing downwind). In order to estimate the economic potential of planned wind farms, the wind industry is therefore very interested in the analysis of wake vortices. 

The Institute of Coastal Research of the Helmholtz-Zentrum Geesthacht (HZG) conducts research on a wide range of issues in the field of offshore wind energy use (Fig. 1). Questions about turbulence and wake vortices are investigated in an interdisciplinary approach. The turbulence researchers led by Jeff Carpenter investigate, for example, small-scale flowing, mixing and transport processes in the ocean by means of direct measurements with ocean gliders and theoretical models. Using measurement data and numerical models, the department led by Joanna Staneva and Johannes Schulz-Stellenfleth is investigating the wind fields behind large wind farms on a large scale. And together with the radar hydrographs (working group led by Jochen Horstmann), they are trying to track down the interactions between wake vortices and swell in the future.” 

The report deals with air turbulence, wake vortices, water stirring and sediment dynamics. Overall, it is well worth reading. The conclusion, as described, is very cautious. Basically, the report says that there are already known effects, there could be significantly more. Whether research funds will be available for such areas, however, remains to be seen.

“An exciting question and task of future research projects is the investigation of coupling, i.e. the interdependencies of processes in air and water. How exactly do the current, the swell and the wind field influence each other? How does the swell change in the turbulence drags in the slipstream of wind turbines and entire wind farms? Even without the influence of wind farms, coupling processes are already extremely complex and become a particularly exciting challenge for scientists from different disciplines due to the additional interactions of the turbines with the boundary layer. Research in the field of process coupling is of broad interest and applicable in many respects, for example for studies on climate change.” 

In spirit, one can add another 1 tonne of heavy metal per year as a burden for every plant in the open sea. Helmholtz Hereon also had a very interesting articleon this. It reads something like the aforementioned report. There are strong hints, but it is better not to say them openly, otherwise a false picture could arise.

“The experts are currently investigating the corrosion protection of wind turbines, in which galvanic anodes, the so-called “sacrificial anodes”, are used. Sacrificial anodes are large metal blocks that are attached all around to the outer skin of the foundations. They are made of aluminum, to which a whole range of other elements are added. The sacrificial anodes prevent the steel from corroding in salty seawater. Instead of steel, the seawater attacks the inferior aluminum-metal mixture.  

While the steel is protected, the sacrificial anodes dissolve over time. This dissolution process is continuous and leads to the sustained release of anode material and the elements it contains. The quantities used in the wind farms are enormous. For example, depending on the type of foundation on its surface, a single wind turbine requires sacrificial anodes with a total weight of up to 10 tons to ensure adequate corrosion protection.

All in all, the many sacrificial anodes in a wind farm release various metals in addition to aluminum over time, including known toxic elements such as lead and cadmium, but also exotic elements such as gallium and indium, about whose behavior in the environment very little is known.”