BDEW calls for longer life for offshore wind farms

09.09.2025

Source: E & M powernews

Offshore wind farms should remain in operation for up to ten years longer before repowering begins. A study commissioned by BDEW recognizes advantages in terms of electricity yield and costs.

The lifetimes of offshore wind farms should be less strictly defined. According to the German Association of Energy and Water Industries (BDEW), greater flexibility in terms of lifetime could lead to higher electricity production and lower overall costs. It derives its position from a study commissioned by the Fraunhofer Institute for Wind Energy Systems IWES.

On September 9, the day the study was published, EnBW also jumped on the bandwagon. Referring to the study, the Karlsruhe-based energy company calls for offshore turbines to continue operating for "as long as possible" instead of dismantling wind farms within a cluster at the same time.

BDEW considers an extension of operation of up to 35 years to be appropriate. According to current licensing practice, the regular operating period expires after 25 years. For the study, Fraunhofer IWES examined the three wind areas (N1-3) in the German North Sea off the East Frisian Islands ("DolWin" cluster), including the turbines that have not yet been connected. According to current regulations, the first wind farms would be decommissioned in mid-2040, the most recent in mid-2053.

Forecast sees falling costs and higher electricity yield

In order to find out whether it makes sense to continue operating and repower offshore wind farms, the researchers took various parameters into account. These included operating and investment costs, failure rates, dismantling and lay-up times as well as the capacities of transport vessels and supply chains.

For five scenarios, the study determined comparative values for the costs per 1,000 kWh and the electricity yield, based on the period from 2040 to 2066. The initial value (scenario 1) was based on the case that a wind farm ceases operation after the previously defined 25 years and direct dismantling and new construction takes place. Here, the study indicates costs of EUR 55.18 per 1,000 kWh.

If the strict replacement regulation were to be abandoned and the operation of each turbine were to last ten years longer, the costs would fall to EUR 49.30 and the electricity yield would drop slightly to 95 percent compared to immediate new construction. In the three other continued operation scenarios, the costs fall in each case (between EUR 50.76 and EUR 53.60 per 1,000 kWh) and the electricity yield increases by around four to ten percent compared to scenario 1.

According to the study, the advantage of the longer operating time of marine turbines lies in the higher electricity yields, for which neither dismantling nor new construction costs are incurred, "especially social costs for the grid connection and price support systems". The more coordinated the continued operation, the higher the electricity yield - despite the expected susceptibility of the old turbines to repairs.

Support comes from EnBW. Michael Splett, Head of Offshore Wind Operations, warns: "If many turbines had to be replaced at the same time, this would put an enormous strain on the supply chains." By contrast, not decommissioning an entire cluster at the same time would allow several offshore wind farms to be dismantled at staggered intervals. This would avoid bottlenecks in port infrastructure and storage capacities.

If, after 25 years, the areas are directly rebuilt with more powerful machines (a 22 MW turbine is assumed here), more electricity can be generated at lower operating costs, according to the study. However, the researchers write that this additional gain would require investments of 23.65 billion euros.

Federal government to revise regulations

Overall, coordinated continued operation would also make sense in other areas, according to the study. It takes pressure off the supply chains through "comparatively moderate requirements". It would also have a lower impact on the marine ecosystem compared to the early dismantling of wind farms and immediate new construction. According to the researchers, the results of the Dolwin cluster cannot be automatically transferred to other offshore areas. Instead, they recommend a precise case-by-case analysis.

In view of the study results, BDEW Managing Director Kerstin Andreae is putting the ball in the politicians' court. The German government should "definitely" take the issue into account in the upcoming update of the area development plan for offshore wind farms.

The "Evaluation of various continued operation and post-utilization scenarios for offshore wind farms and offshore grid connection systems in the German Bight " by the Fraunhofer Institute for Wind Energy Systems IWES is available on the BDEW website,

Author: Volker Stephan