‘Wedding’ on the high seas: 1,400 tonne substation for RWE Kaskasi wind farm installed

Kaskasi is RWE’s sixth wind farm off the German coast, the 342 megawatt project is being built 35 kilometres north of the island of Heligoland and recently celebrated a ‘wedding ‘on the high seas. A ‘wedding’ is what the construction process is called when the substation topside is successfully placed on the foundation. The offshore substation is the heart, where electricity generated by each wind turbine flows together to be converted to the necessary transmission voltage.

The journey of the 1,400 tonne substation topside started in Danish Aalborg at the manufacturing facility of Bladt Industries and took two days to ship across the North Sea. Gulliver, a Floating Heavy Lift Vessel of SCALDIS, placed the substation onto the monopile foundation, completing the installation of the heaviest component of the Kaskasi offshore wind farm.

In parallel, foundation installation works are underway: With Seaway 7’s Strashnov, DEME’s Neptune and Sea Challenger and Fred Olsen’s Blue Tern, four vessels are engaged in the installation of a total of 38 monopile foundations for the wind turbines and their transition pieces. The foundations, each up to 64 metres long, weigh up to 740 tonnes – approximately equivalent to 600 small cars. The operations and processes at the offshore construction site are coordinated around the clock by the RWE Control Room on Heligoland. The nautical staff at Ems Maritime Offshore are supporting the RWE team.

To install the foundations into the seabed at depths of 18 to 25 metres, RWE is utilising two installation methods: conventional hammering and innovative vibro pile driving technology, which has the potential to reduce underwater noise emissions. This benefits the marine environment in particular. The pilot implementation of the vibro technology at Kaskasi is accompanied by the “VISSKA” research project, which is funded by the German Federal Ministry of Economic Affairs and Climate Action.

Innovative foundation solutions and recyclable rotor blades

RWE is leading technological development in the offshore wind industry. At the Kaskasi offshore wind farm, three new technologies will be tested. RWE plan to install special collars around
three monopile foundations (Collared Monopile). A further innovation is the introduction of foundations which were installed using vibro pile driving and are enclosed in a concrete ring that expands in the seabed (Self-Expanding Pile Shoe). In addition, a sustainable product will be celebrating its German premiere at Kaskasi: Siemens Gamesa and RWE will equip a number of wind turbines with recyclable rotor blades. The blades are the first of their kind, thanks to an innovative resin that enables components to be recycled for new applications at the end of their lifecycle. Installation of the wind turbines is scheduled to start this summer. By the end of 2022, a total of 38 wind turbines are to be fully operational. Then, the Kaskasi offshore wind farm will have the capacity to supply the equivalent of approximately 400,000 households with green electricity every year.

Tailwind for RWE and the energy transition in Germany

RWE is one of the leading companies in the field of renewable energies and No. 2 worldwide in offshore wind. As part of its ambitious investment and growth strategy, “Growing Green”, the company plans to triple its global offshore wind capacity by 2030, thus increasing from the current 2.4 gigawatts (GW) to 8 GW. Also in Germany, RWE is stepping up the pace: by 2030, the company intends to invest up to 15 billion euros in the green energy sector. RWE continues to expand in the offshore wind energy market too: together with its Canadian partner, Northland Power, RWE is driving forward the development of a large offshore wind cluster in the German North Sea. The partners plan to construct a cluster of three wind farms north of the German island of Juist with a total installed capacity of over 1.3 GW, which are expected to commence operation in 2026 and 2028 respectively. These planned offshore wind farms will be able to produce enough green electricity to meet the requirements of up to 1.6 million households per year. RWE is also developing a further wind farm in the direct vicinity with a capacity of 225 megawatts.