Kaskasi Offshore Substation Topside Touches Down

The 1,400-tonne offshore substation topside has been installed on its monopile foundation at the 342 MW Kaskasi offshore wind farm in the German North Sea, RWE, the owner and developer of the project, said.

The topside was installed by the heavy lift, DP 2 installation vessel Gulliver, operated by DEME’s subsidiary Scaldis Salvage & Marine Contractors.

Kaskasi is RWE’s sixth wind farm off the German coast and is being built 35 kilometres north of the island of Heligoland.

The journey of the topside started in Aalborg, Denmark at the manufacturing facility of Bladt Industries and took two days to ship across the North Sea.

In parallel, the turbine foundation installation works are underway. With Seaway 7’s Strashnov, DEME’s Neptune and Sea Challenger, and Fred Olsen Windcarrier’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.

This is the first time that Fred. Olsen Windcarrier has been involved in installing foundations. A few weeks ago, Blue Tern left Fayard in Denmark where she underwent upgrade work and ten-year class renewal and went straight on to the Kaskasi project.

”This is a very exciting project for us as this is our first monopile foundation scope. This is also the first time we have been contracted directly by RWE and we are glad to have been picked by them as a reliable and competent partner. We look very much forward to partnering with them on this project,” Gerard Toh, Commercial Manager at Fred. Olsen Windcarrier, said.

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 developer said.

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.

The Kaskasi wind farm will be a testing ground for three new technologies.

RWE plans to install special collars around three monopile foundations – the so-called collared monopiles.

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 – the Self-Expanding Pile Shoe.

In addition, 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, RWE said.

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.

”If Germany wants to supply itself almost entirely with electricity from renewable energies by 2035, this will require a huge effort,” Sven Utermöhlen, CEO Wind Offshore, RWE Renewables, said.

”Faster offshore expansion is particularly important to simultaneously achieve the climate targets and more energy sovereignty. We want to help make this happen and the fact that construction of our Kaskasi offshore wind farm is now picking up pace is a clear sign of this.”

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