With the cable-laying vessel Isaac Newton, the work vessel Adhémar de Saint-Venant and a remote-controlled cable burial vehicle, the contractor combination Jan de Nul Group/LS Cable & System has completed the installation of the second subsea cable for the offshore wind farm ‘west Alpha’. In recent weeks, more than sixty kilometres of cable have been laid in the seabed between the beach of Heemskerk and the ‘socket’ that grid manager TenneT is having built at sea.
Last summer, Jan de Nul pulled four sea cables from the beach of Heemskerk in conduits under the dunes. After installing the two sea cables for the Hollandse Kust (north) wind farm, the first kilometres of the two cables for ‘west Alpha’ were laid capped in the seabed. After successfully installing the first sea cable, Jan de Nul brought the capped part of the second cable for ‘west Alpha’ above the water in April – about five kilometres from the beach.
After the coupling by the team of the South Korean cable manufacturer LS Cable & System, the cable was laid back on the seabed. At the same time, the work vessel Adhémar de Saint-Venant appeared off the coast with the UTV1200 unmanned cable-laying vehicle on board. As soon as the Isaac Newton set sail, the cable slowly unwound from the large turntable on board. Later followed by the Adhémar de Saint-Venant for the steering of the UTV1200, which then laid the cable in the seabed.
Off the coast
TenneT had placed the steel jacket for the transformer platform on the seabed 50 kilometres off the coast of Egmond aan Zee last August. The turbines of the wind farm will soon be connected to this socket. With the retraction of the last cable via the cable deck, the job is done for the contractor combination.
Thijs den Hamer, project leader on behalf of TenneT, looks back with satisfaction on this part of the project. “With the installation of the sea cables for the wind farms ‘north’ and ‘west Alpha’, the contractor has delivered a great performance within the intended schedule. After the summer, we will have the ready-made superstructure (topside) placed on the base, after which we can test the cable connections.”
Partly tested and ready
For testing, this concerns the connection between the socket for ‘west Alpha’ and the transformer station in Wijk aan Zee. Den Hamer: “From the transformer substation in Wijk aan Zee to our high-voltage substation along the A9 motorway near Beverwijk, all circuits for the three wind farms Hollandse Kust (north), (west Alpha) and (west Beta) have already been tested and are ready for use. ”
Connection West Alpha
Once the tests are completed, TenneT will deliver the connection for ‘west Alpha’ in the first quarter 2024. It will then be the turn of operator Ecowende (Shell/Eneco) to have the wind farm built so that the turbines at sea can produce energy from wind in 2026. With a capacity of 700 megawatts, the amount of sustainable energy that will then be brought ashore by TenneT corresponds to 2.5 to 3 percent of current consumption in the Netherlands.
Image source: Courtesy of TenneT
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