RWE and DEME team up for innovative collared foundaions

4C Offshore | Bridget Randall-Smith
By: 30/11/2020 RWE
DEME Offshore are to install innovative collars for the  first time on the foundations at RWE's Kaskasi offshore wind farm.

The ‘collared monopile’ was developed by the German civil engineering company JBO based on the RWE patent. The new technology will provide additional support for lateral loading, increase the bearing capacity and improve the structural integrity of the entire foundation – especially in difficult ground.


RWE Renewables has signed a contract with DEME Offshore for the transport and installation of the new foundation technology at RWE’s 342-MW
Kaskasi offshore wind farm, located in the German North Sea, 35 kilometres north of the island of Heligoland.

Sven Utermöhlen, Chief Operating Officer Wind Offshore Global at RWE Renewables, says:  “At our Kaskasi offshore wind farm we use innovative technologies that will set standards throughout the offshore industry. The collared monopile, a patented solution developed  in-house, will help to increase stability in difficult ground. Furthermore, Kaskasi will be the first commercial offshore wind farm in the world to use an improved installation method to drive all monopile foundations to target penetration. The vibro pile driving technique will reduce both installation time as well as noise emissions for marine life. This showcases our technical expertise as the second biggest player in offshore wind globally and means that we will continue to be at the forefront of the evolution of technology in this industry.”


Bladt Industries was selected as manufacturer. DEME Offshore will transport the three collars from the manufacturer’s load-out port in Aalborg, Denmark, to the
Kaskasi construction site near Heligoland. Then the DEME Offshore team will install the steel collars around three of the 38 monopile foundations using the jack-up vessel NEPTUNE. The collar will be installed at seabed level in water depths of up to 25 metres. The space between collar and monopile foundation will be filled with grout material to create a stable connection. RWE will carry out accompanying tests to verify that the collar improves the structural behaviour in comparison to standard monopiles.

Bas Nekeman, Business Unit Director Northern Europe at DEME Offshore, emphasises:  “The Kaskasi collar installation project is a good example of how we can bring added value to our clients. Our versatile fleet of offshore installation vessels enables us to deploy the ideal vessel for this project and, in close collaboration with our client, we are tailoring the installation techniques and minimising any potential risks.”


Kaskasi will also be the first commercial offshore wind farm in the world using “vibro pile driving”. The technique is an efficient alternative to the conventional method of hammering monopiles into the seabed. This improved installation method could reduce installation time and noise emissions during construction.

The installation of the foundations will start in the third quarter of 2021 with commercial operations in summer 2022. Once all wind turbines are fully operational, the farm will supply the equivalent of more than 400,000 homes with green electricity.



Kaskasi is RWE’s sixth wind farm off the German coast. The company operates the nearby offshore wind farms Nordsee Ost (295 MW) and Amrumbank West (302 MW) as well as Arkona, which is with an installed capacity of 385 MW (RWE share 50%) the largest offshore wind farm in the Baltic Sea.

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