Innovative foundation technology that improves the load-bearing capacity of a monopile foundation on an offshore wind turbine is to be introduced on RWE’s Kaskasi offshore windfarm
The ‘collared monopile’ with a collar at seabed level was designed based on an RWE patent. The collar provides additional support for lateral loading, increasing the bearing capacity of the monopile and improving the structural integrity of the entire foundation in difficult ground.
RWE Renewables has signed a contract with DEME Offshore for installation of the new foundation on its 342-MW Kaskasi offshore windfarm in the German sector of the North Sea, 35 km north of the island of Heligoland.
RWE Renewables chief operating officer wind Sven Utermöhlen said, “We will use a number of innovative technologies at Kaskasi. The collared monopile, a patented solution developed inhouse, will help to increase stability in difficult ground.
“Kaskasi will be the first commercial offshore windfarm to use an enhanced installation technique to drive all of the monopile foundations to target penetration. The vibro pile driving technique will reduce installation time and noise levels.”
The design of the collars was developed by German civil engineering company JBO based on the RWE patent. Bladt Industries was selected as manufacturer.
DEME Offshore will transport the collars from the manufacturer’s load-out port in Aalborg, Denmark. It will install the steel collars around three of the 38 monopile foundations for which DEME Offshore will deploy the jack-up vessel Neptune.
The collar will be installed at seabed level in water depths of up to 25 m. The space between collar and monopile foundation will be filled with grout material to create a stable connection.
RWE will carry out tests to verify that the collar improves structural behaviour compared to standard monopiles.
The Kaskasi offshore windfarm will consist of 38 wind turbines. Each turbine will have a capacity of up to 9 MW. Installation of the foundations will start in Q3 2020 and it is expected that Kaskasi will start commercial operation mid-2022.