Corrosion protection at offshore wind farms could lead to increased concentrations of metals in seawater and seabed. This was announced by the Federal Maritime and Hydrographic Agency and the Helmholtz-Zentrum Hereon in a joint press release. A research team examined water and soil samples from the vicinity of wind turbines in the North Sea. The concentrations found were largely within the range of the known variability for the North Sea. However, occasionally increased concentrations of aluminum, zinc, indium and gallium were noticed. In addition, the sediment partly contained locally increased concentrations of lead. So far, however, no direct effects on the marine environment have been seen, said the Federal Office.
The sporadically increased values could possibly be due to certain weather conditions in which the water around the offshore plants was mixed only minimally. The causes of the locally increased lead concentrations have not yet been clearly identifiable.
The metals are used in galvanic anodes, the victim anodes that prevent the corrosion of offshore steel structures. But they dissolve themselves. Indium and gallium naturally hardly occur in the sea. They are therefore considered tracers who reveal the origin of the emissions from the victim anodes. According to the press release, 150 to 750 kilograms of the anode material are currently reaching the marine environment per year and wind complex.
According to the Federal Office, more than 1,500 wind turbines are already in operation in the North Sea and the Baltic Sea, and there are also 30 spanning and converter platforms off the German coasts. With the further expansion of wind energy at sea, emissions from corrosion protection could increase, the Federal Office fears. The wind farm operators should therefore increasingly use external current anodes in the future, which only emit very small amounts of substances to the marine environment.
