Hollandse Kust Zuid Alpha jacket installed

In: Substations
07/09/2020
The Hollandse Kust Zuid Alpha substation jacket foundation was installed off the Dutch coast over the weekend. The 3,200 ton jacket was transported and installed by the heavy lifting crane vessel the Sleipnir.

The jacket is 29 metres long, 20 metres wide and 46 metres high. It is the foundation for the first of two transformer substations of the Hollandse Kust Zuid offshore wind farms. The two 220 kV sea cables that bring the power from the wind farms ashore will be connected to the Alpha jacket in the next months. In 2021, the top side of the substation will be installed onto the jacket. At the end of 2021, the offshore platform is expected to be in operation.

Vattenfall will use the Alpha and Beta platforms to connect the Hollandse Kust Zuid wind farms to the grid. Vattenfall secured the rights to the  
Hollandse Kust Zuid 1&2 and Hollandse Kust Zuid 3&4, offshore wind farms, with zero subsidy bids in March 2018 and July 2019. The projects have a combined capacity of 1.5 GW and will feature 140 SG 11.0-200 DD turbines. Offshore construction is scheduled to start in 2021, with commissioning in 2023.

By the end of 2023, TenneT aims to have constructed 3,500 MW offshore grid connections for offshore wind farms. The first 1,400 MW has been realised with the delivery of Borssele Alpha and Beta. This will be followed by Hollandse Kust Noord. TenneT is using five identical 700 MW transformer platforms for these wind farms. These platforms are located close to the wind farms and all five use the same type of 220 kV cable connections to the coast.

According to the Follow-up Roadmap for Offshore Wind Energy, a further 6.1 GW (6,100 MW) of offshore wind farms will be built from 2024 through to the end of 2030. These wind farms will be located in the wind energy areas known as Hollandse Kust West, Ten Noorden van de Waddeneilanden and IJmuiden Ver. For the first two, TenneT will again be using three standardised 700 MW platforms (2.1 GW).


The connection of wind energy areas further out into the North Sea, such as IJmuiden Far (4 GW), will partly require other technologies that use direct current instead of alternating current. IJmuiden Ver will have two offshore converter stations, each with a capacity of 2 GW, which is unique in the offshore wind industry.

In the German part of the North Sea, TenneT's 7.1 GW current connection capacities already exceeds the German government's target for 2020. This target has been set at around 6.5 GW for the North Sea and the Baltic Sea together. By 2030, TenneT anticipates its offshore grid connection capacity in Germany will increase to around 17 GW.


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