Offshore renewables company RWE Renewables has this week seen the 1,400-tonne Kaskasi offshore wind farm substation topside installed onto the monopile foundation, off Germany.

The 342-megawatt Kaskasi offshore wind project is being built 35 kilometers north of the island of Heligoland. The offshore substation is where electricity generated by each wind turbine flows to be converted to the necessary transmission voltage.

The substation topside was shipped from Danish Aalborg where the manufacturing facility of Bladt Industries is located, and it took two days to ship across the North Sea.©RWE 

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.

RWE said that the installation of wind turbine foundations and transition pieces was underway as well.

Seaway 7’s Strashnov, DEME’s Neptune and Sea Challenger, and Fred Olsen’s Blue Tern 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 meters long, weigh up to 740 tonnes – approximately equivalent to 600 small cars.Vibro pile driving at Kaskasi ©RWE 

Hammering and Vibro Pile Driving 

To install the foundations into the seabed at depths of 18 to 25 metres, RWE is utilizing two installation methods: conventional hammering and innovative vibro pile driving technology, which has the potential to reduce underwater noise emissions, benefitting the marine environment.

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. RWE said.

Three new technologies

According to RWE, at the Kaskasi offshore wind farm, three new technologies will be tested. RWE plans to install special collars around
three monopile foundations (Collared Monopile). A further innovation is the introduction of foundations which, as mentioned earlier, 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, RWE said, as 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,” RWE said.

Also, in a Linkedin post on Thursday, Seaway 7 said it had installed the first monopile foundations on Dynamic Positioning (DP) on the Kaskasi project.

“This is the world’s first commercial monopile installation on DP mode. Installation of monopiles on DP will significantly reduce installation time and cost by avoiding the need to anchor on each location. Following a multi-year R&D program, we first successfully demonstrated this technique in 2019, now coming full circle with installation on a commercial project,” the company said.

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.

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