Tech

Dismantling wind turbines at sea – new opportunities for ports?

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The dismantling of wind turbines in the North Sea will increase significantly in the coming years and will be more expensive than planned. This is the result of studies by the Hamburg Economic Research Institute HWWI and other institutions that have come together in a joint international project. According to the HWWI, 22 wind turbines have to be removed from the North Sea this year. In 2023 there will be 123 turbines and in 2030 more than 1000 wind turbines that have reached the end of their service life.



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Due to the difficult weather conditions at sea and complex maintenance, the technical durability of offshore wind turbines is estimated to be only 20 to 25 years, which is five to ten years shorter than on land. The plants are then either completely renewed and strengthened (repowering) or completely dismantled and disposed of.

The German offshore wind power plants are initially not affected because the oldest turbines are only ten years old. However, there are older wind power plants in the North Sea, for example in Scandinavia, the Netherlands and Great Britain.

The participating companies have already gained initial experience with the dismantling of offshore wind power plants in the past years at around 20 individual plants and small wind farms in several countries, primarily in Sweden and Denmark. However, there is no standardized procedure yet, the industry is too young for that. The dismantling should be as environmentally friendly as possible and release little CO2.

"The previous dismantling projects have revealed a lack of documentation," said HWWI researcher Mirko Kruse. "For example, the materials used for the plants were not listed in detail, and the amount of concrete used in the foundation was also significantly higher than originally assumed." Not all companies that pioneered the first wind turbines in the sea still exist – and therefore no construction documents.

The legal framework between the individual countries bordering the North Sea are also regulated differently, and the details even contradict each other, the study says. So far, it has not been uniformly regulated whether the concrete foundations of the plants can remain in place, for example, while only the superstructures are being removed, or what happens to the power cables on and in the seabed.

The wind power industry is undergoing the same development as oil and gas production before, which after the depletion of the fields has to dismantle hundreds of production platforms in the North Sea. There are already many highly specialized companies for this; it's about a billion dollar business.

The situation in the wind industry could be similar. At the latest when the number of aging systems increases, the demolition also turns into a profitable business for specialized companies and locations. "We need good dismantling concepts in order to operate economically and ecologically efficiently and thus also work sustainably," said Silke Eckardt, professor for future-oriented energy supply and resource efficiency at the Bremen University of Applied Sciences.

The cost of dismantling a wind turbine is between two and ten percent of the investment costs, depending on the location and equipment, and should not be neglected. There are already more than 4,500 wind turbines in the North Sea, and the number is increasing every year.