Hollandse Kust Noord: inter-array cables installed

Van Oord has completed installing and burying inter-array cables at CrossWind’s Hollandse Kust Noord offshore wind park, bringing it a step closer to being fully operational by the end of this year. 

The cables are used for connecting the offshore wind turbines and transmitting electricity. Van Oord’s top duo cable-laying vessel Nexus and trencher Dig-It (a remotely-operated vehicle operated from vessel Subsea Viking) have installed a web of 69 inter-array cables measuring 140 km in total. The offshore wind park is located 18.5 kilometres off the coast of the Netherlands, near the seaside resort of Egmond aan Zee.

Van Oord designed a 66kV inter-array grid for the Hollandse Kust Noord offshore wind park, to guarantee reliable and safe transmission of the generated electricity. Dutch manufacturer TKF (Twentsche Kabelfabriek) supplied the cables. Nexus, equipped with a large 5,000 tonnes capacity cable carousel, installed the inter-array cables. Trencher Dig-It subsequently buried the cables to the required depth of between 1.0 and 1.5m. The Dig-It, a Tracked Remotely Operated Vehicle (TROV), can be used for burying cables both in “jetting mode” for sandy soils and in “chain cutter mode”’ for harder soils. At the Hollandse Kust Noord project both modes were used successfully.

Wind park developer Crosswind, a joint venture between Shell and Eneco, contracted Van Oord for the complete Balance of Plant scope for the construction of the offshore wind park. As a Balance of Plant contractor, Van Oord’s activities encompass the design, engineering, procurement and transport and installation of the wind turbine foundations, inter-array cables, as well as the transport and installation of the wind turbines themselves. Earlier this year, Van Oord completed the installation of all 70 monopile foundations for the wind park. Currently, Van Oord is deploying two offshore installation vessels to install the wind turbine generators and is also performing the electrical termination works of the cables in the wind turbine generators.

While construction is still in full swing, the Hollandse Kust Noord offshore wind park already produced its first megawatt hours (MWh) of green electricity and delivered it to the Dutch mainland. In coming months, production capacity will be constantly increased. Once finished, the wind park will have a total installed capacity of 759 MW, generating at least 3.3 TWh per year. This is enough renewable electricity to meet 2.8% of the Netherlands’ electricity demand.