After extensive preparation and three years of construction on land and sea, the grid connection for Hollandse Kust (west) Alpha is officially ready for commissioning. This means that wind farm operator Ecowende can connect the wind turbines, which will be located about 50 kilometres off the coast of Egmond aan Zee, to grid operator TenneT’s ‘socket’ at sea.

Whereas completion was scheduled for the first quarter of 2024, TenneT received the grid readiness certificate from DNV before the holidays in 2023. This makes the ‘socket at sea’ grid connection to the national electricity grid officially ready for use after a series of extensive tests. Via the cable connection coming ashore at Heemskerk/Wijk aan Zee, power has been put on this new part of the grid from the high-voltage substation along the A9 near Beverwijk.


“With this, we finished three months ahead of schedule,” TenneT interface and system integration manager Anne-Marie Taris announced. She is responsible for the system integration and flawless cooperation of the transformer station in Wijk aan Zee, the underground (sea) cable connection and the platform at sea. “A fine achievement that the Equans/Smulders contractor combination can also be proud of. Both the teams at sea and on land have done a great job in recent months.”

A connection every year

In 2016, the national government designated TenneT as the offshore grid operator. This means that TenneT will connect the new offshore wind farms to the national high-voltage grid. The Ministry of Economic Affairs and Climate commissioned five standardised grid connections of 700 megawatts by 2024. A connection from sea to land has been completed every year since 2019.

Within schedule and budget

Taris: “In the Energy Agreement ten years ago, it was agreed that by the end of 2023, at least 4.5 gigawatts of installed capacity for wind at sea had to be realised. That is equivalent to the annual consumption of five million households. That assignment has been achieved on schedule and on budget by all parties involved. Earlier than planned, grid connection number six has now been added with Hollandse Kust (west) Alpha.”

Second platform

Last September, the more than 3,600-ton superstructure (topside) of the offshore socket was placed on the undercarriage (jacket). Almost two years earlier, the first steel cut took place in Antwerp for this second transformer platform built by Equans/Smulders for TenneT. Sustainable electricity is already being brought ashore from the first platform for wind farm Hollandse Kust (north).

Timely completion

Following the topside installation, a hotel ship was placed next to the platform so that the Equans/Smulders team could carry out the welding work and further installation. Earlier, Jan de Nul Group and LS Cables installed the two sea cables that will soon bring the green power ashore in 2023. “Despite the challenging weather conditions of recent times, we managed to perfectly complete the installation of the platform and all the test work for the connection in a timely manner,” Taris said.


Now that the grid connection is ready for use, the wind farm operator Ecowende (a joint venture between Shell and Eneco) can connect the wind turbines in the offshore wind farm as soon as they are built. With an installed capacity of about 760 megawatts, Ecowende is going to green about 3% of the current Dutch electricity demand in the coming years. The wind farm is expected to be commissioned in 2026.

Image source: Courtesy of TenneT

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