RWE and DEME Offshore install collars on offshore foundations
An innovative foundation technology is to be introduced at RWE’s Kaskasi offshore wind farm, DEME said in its release. For the first time ever in the renewables industry special collars will be installed around the monopile foundation at seabed level. The ‘collared monopile’ is designed based on an 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. DEME Offshore is delighted to partner with RWE in this pioneering project, which highlights how both companies are focusing on further refining innovative technologies and new concepts in the renewables sector.
The Kaskasi offshore wind farm will consist of a total of 38 wind turbines. Each turbine will have a capacity of up to 9 MW. The wind turbines will be installed on monopile foundations. The installation of the foundations will start in the third quarter of 2021. RWE will use the “vibro pile driving” installation method, which 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. Kaskasi will be the first commercial offshore wind farm in the world using the vibro driving technique to install all monopile foundations to target penetration. This underlines RWE’s ambition to be a frontrunner in driving innovation and technology.
When target penetration is reached, the innovative foundation collars will be implemented at three locations. The detailed design was developed by the German civil engineering company JBO based on the RWE patent. 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 for which DEME Offshore will deploy the versatile 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.
It is expected that the Kaskasi wind farm will start commercial operations in summer 2022. Once all wind turbines are fully operational, the wind farm will supply the equivalent of more than 400,000 homes with green electricity.
About DEME Group
DEME is a world leader in the highly specialised fields of dredging, solutions for the offshore energy market, environmental and infra marine works. The company can build on more than 140 years of know-how and experience is a front runner in innovation and new technologies.
DEME’s vision is to work towards a sustainable future by offering solutions for global challenges: a rising sea level, a growing population, reduction of CO2 emissions, polluted rivers, seas and soils and the scarcity of natural resources.
While the company’s roots are in Belgium, DEME has built a strong presence in all of the world’s seas and continents, operating in more than 90 countries worldwide. DEME can rely on 5,200 highly skilled professionals across the globe. With a versatile and modern fleet of over 100 vessels, backed by a broad range of auxiliary equipment, the company can provide solutions for even the most complex projects.
DEME achieved a turnover of 2.62 billion euros in 2019.