The world’s first commercial-scale floating wind farm, Hywind Scotland, is now back in Scotland and online after its five turbines were towed to Norway for maintenance.

The 30 MW Hywind Scotland has been in operation since 2017. Located 25 kilometers (15.5 miles) off Peterhead in Aberdeenshire, it comprises five Siemens Gamesa 6 MW turbines mounted on SPAR-type foundations. It’s a pilot project that’s demonstrated the feasibility of floating wind farms that could be 10 times larger, and it also delivers enough power to supply around 35,000 homes in the UK.

Norwegian energy company Equinor asserts that each year since Hywind Scotland started production, it’s achieved the highest average capacity factor of all UK offshore wind farms.

Operational data indicated that a heavy maintenance campaign for the wind farm’s turbines was needed, so Equinor and its Emirati renewable energy company partner Masdar decided in January that towing the turbines to Wergeland Base, on the west coast of Norway, would allow the maintenance to take place in a controlled, sheltered environment before being sent back and reconnected. (They originally estimated a timetable of up to four months.)

Belgian heavy lifting and engineering firm Sarens replaced the bearings in the five turbines. Sarens’ scope of work included the provision of cranes to lift and transport the turbines’ nacelles and blades and the delivery of a skidding system to move the generator in and out of the workshop.

Trine Ulla, Equinor’s VP of UK operations, said, “Through this maintenance campaign, we’ve gained valuable insights that will help us refine maintenance practices and optimize this technology for the future. By sharing our learnings, we aim to contribute to the growth and development of the floating wind industry.”