Jan De Nul Group has completed the export cable installation works in the German North Sea that connect the offshore wind farms Trianel Windpark Borkum II, developed by Trianel, and Borkum Riffgrund II, developed by Ørsted, to Tennet’s German transmission grid.
For both cable installation projects, Jan De Nul Group’s cable laying vessel Willem de Vlamingh and trenching support vessel Adhémar de Saint-Venant were mobilised.
Willem de Vlamingh
In the summer of 2017, the Willem de Vlamingh identified and removed potential UXOs from the cable routes. In the spring of 2018, it sailed to the cable load out facilities in Greece to load the three cables with a total length of 26.4 km. The Willem de Vlamingh completed the installation of all three cables on 25 April 2018.
Connecting Offshore Wind Farms
The first two cables connect the Borkum Riffgrund II wind farm substation with the Dolwin Gamma convertor station. The third cable connects the Trianel Windpark Borkum II with the Dolwin Alpha convertor station. These Dolwin platforms convert the electricity generated by the two wind farms into Direct Current (DC) before transporting it to Tennet’s onshore network.
Trenching
The trenching support vessel Adhémar de Saint-Venant executed the cable protection works by means of post-lay jet trenching using Jan De Nul Group’s UTV1200 trencher. Trenching was completed on 16 May 2018.
Final Commissioning
The Greek cable manufacturer Hellenic Cables is currently terminating and testing the cable connections. Overall commissioning is planned in June/July 2018.
