Lifetime extension of Bockstigen offshore wind farm on Gotland

The offshore wind farm is located in Bockstigen on Gotland, Sweden, and is notable for being the third offshore wind farm to be established in the world. Bockstigen was built in 1998. The project consisted of five 20-year-old Wind World 550 kW wind turbines, which have been generating electricity since their installation.

The offshore wind farm is located in Bockstigen on Gotland, Sweden, and is the third offshore wind farm established in the world. Bockstigen was built in 1998. The project consists of five 20-year-old Wind World 550 kW wind turbines, which have been generating electricity since their installation. When we made the decision, 4 out of the 5 wind turbines were still working, but all were close to the end of their technical lifespan. The low electricity prices and lack of government subsidies meant that the future of the project was uncertain and some important decisions had to be made.

Momentum laid out a plan to replace existing wind turbines with refurbished or new wind turbines. It was eventually decided that the nacelles, rotors and transformers from the old wind turbines would be replaced with refurbished Vestas V47 nacelles and new DEIF transformers and monitoring systems.

The repowering process was financed by various banks and the owners’ equity. Momentum was responsible for purchasing used Vestas V47 wind turbines (rotors and nacelles) in Germany and refurbishing them in Denmark. The old wind turbines were replaced with the refurbished wind turbines, after which the old ones were dismantled and dismantled. All five turbines have been back in full operation since November 2018. Less than a year passed between the planning phase and the operational phase.