Innovative collars for monopile foundations have been installed for the first time on an offshore windfarm at RWE’s 342-MW Kaskasi project
Installed around the monopile and embedded into the seabed, the collars provide additional support against lateral loading, increasing the bearing capacity and structural integrity of the foundation.
RWE Renewables chief executive offshore wind Sven Utermöhlen said, “The collared monopile – a patented solution we developed inhouse – will help to increase the stability of the foundation, and turbine, in difficult ground.”
Three foundation collars have been installed on the German windfarm. Each is 7 m high and weighs 170 tonnes. Installation, in water depths of up to 25 m, was carried out by DEME’s jack-up vessel Sea Challenger.
The space between collar and the monopile foundations is filled with grout, creating a stable connection. RWE will carry out tests to verify the collar improves structural behaviour compared with standard monopiles.
The detailed design of the collars was developed by the German civil engineering company JBO. Bladt Industries in Denmark manufactured them.
The collared monopile is one of a number of innovations being tested on the Kaskasi windfarm. Others include the use of vibro pile driving technology and a ‘self-expanding pile shoe,’ a new type of foundation with a concrete ring that expands in the seabed.
Wind turbine OEM Siemens Gamesa will fit a number of wind turbines installed at Kaskasi with recyclable rotor blades. The blades are the first of their kind and use an innovative resin that enables the blades to be recycled for new applications at the end of their lifecycle. Installation of the wind turbines is scheduled to start mid-year.
