Monopile installation is set to become much quicker as foundations are installed from DP vessels
RWE’s Kaskasi offshore wind project is unique for several reasons. The project is acting as a ‘research lab’ for new technology, not least new ways to install monopile foundations.
Monopiles remain the foundation of choice for most offshore windfarms. They are usually installed from a jack-up vessel, but on Kaskasi, a number of the monopiles are being installed from a dynamically positioned (DP) vessel, using a new type of pile gripper and innovative pile driving technology. The DP system on the vessel has also been modified to create a ‘coupled system’ that enables it to ‘talk’ to the control system in the motion-compensated gripper.
In April 2022, Kaskasi contactor Seaway 7 confirmed its vessel Seaway Strashnov had successfully installed the first monopile foundation for the project using DP mode. This was a world first.
“Installing monopiles on DP will significantly reduce installation time and cost by avoiding the need to anchor on each location,” says the company, which pioneered the concept and co-developed the technology required during a multi-year R&D programme. The company first demonstrated the technique in 2019 on a pilot project. Once in service, the company’s new vessel Alfa Lift will work in this way.
On Kaskasi, Seaway 7 also utilised innovative vibro pile driving technology to reduce underwater noise emissions. The technology was developed by Seaway 7 working with CAPE Holland, who built and provided what is currently the world’s largest vibro lifting tool for the project.
The CAPE VLT-640 vibro lifting tool used on the Kaskasi project is capable of 640 kg per unit. Three of the units were combined to form the ‘CAPE VLT-640 Triple’ used on Seaway Strashnov.
“This machine is ready for monopiles weighing more than 1,000 tonnes,” says Cape Holland, noting that new units are being developed that will be capable of upending, lifting and driving the largest XXL monopiles, weighing up to 3,000 tonnes. Monopiles of this size will be required for wind turbines of up to 20 MW.
The Offshore Wind Journal Conference will be held 14 June 2022. Details and tickets can be found here
© 2023 Riviera Maritime Media Ltd.