RWE installs steel collars installed at Kaskasi

4C Offshore | Tom Russell
By: 08/06/2022 RWE

RWE has for the first time installed special collars around monopile foundations at seabed level on its
Kaskasi offshore wind farm. Installation works were carried out by DEME Offshore.

The collared monopile is a design based on an RWE patent and aims to provide additional support for lateral loading, increase the bearing capacity and improve the structural integrity of the entire foundation. In total, three foundation collars were embedded into the seabed – each 7 metres high, weighing 170 tons.


The installation in water depths of up to 25 metres was carried out by the jack-up vessel ‘Sea Challenger’ from DEME Offshore. The space between collar and monopile foundation was filled with grout material, creating a stable connection. RWE will carry out accompanying tests to verify that the collar improves the structural behaviour in comparison with standard monopiles.


The detailed design of the collars was developed by the German civil engineering company JBO based on the RWE patent, Bladt Industries was selected as manufacturer and DEME Offshore was responsible for the transportation and installation.

Sven Utermöhlen, CEO Offshore Wind, RWE Renewables, said: “At our Kaskasi offshore wind farm we use innovative technologies that will set standards throughout the entire offshore industry. It’s a great credit to the project team and our contractors that we developed, manufactured and safely installed the three innovative foundation collars. The collared monopile, a patented solution developed in-house, will help to increase stability in difficult ground. This showcases our technical expertise as the second largest player in offshore wind globally.”

Bas Nekeman, Business Unit Director Northern Europe at DEME Offshore, emphasised: “Whilst these monopile foundation collars represent only a relatively small scope of work DEME Offshore is performing at the Kaskasi offshore wind farm, we are extremely happy achieving this important milestone for the project. The installation of these type of structures is a world’s first which required us to develop a tailor-made solution. The completion of the three monopile foundation collars demonstrates our ability to deliver our customers the right technical know-how, operational excellence and team spirit required for the successful delivery of these types of innovative projects.”


RWE is testing further innovations at
Kaskasi including vibro pile driving technology and the Self-Expanding Pile Shoe, a new foundation solution with a concrete ring that expands in the seabed. In addition, Siemens Gamesa and RWE will equip a number of wind turbines with recyclable rotor blades. The blades consist of 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.

The 342 MW
Kaskasi wind project is located 35 kilometres north of the island of Heligoland, Germany. The project is planned to be fully commissioned by the end of 2022. Once fully operational, the project is expected to supply the equivalent of 400,000 households a year with green energy.

For more information on offshore wind farms worldwide, click here.