The two Alpha cables of TenneT’s Hollandse Kust zuid offshore grid connection have been successfully pulled in at the HKZ Alpha jacket. The installation of the cables started on September 22nd by pulling the cable ashore at the Dutch Maasvlakte. Van Oord’s Deep Dig-It trencher then crossed the Rotterdam Maasmond to bury the cables 5,5 metres deep for the first 10 kilometres. The cable has now reached the recently installed offshore Alpha jacket in the Hollandse Kust (zuid) wind farm area. The total length of the 220 kV cable that is approximately 42 kilometres.

The Van Oord/Hellenic Cable Consortium will be installing 4 subsea 220 kV AC cables that will connect 2 offshore platforms to the onshore electricity grid. The first 2 cables to the Alpha platform have now been installed. The other 2 cables, meant for the Beta platform, will follow in 2021.

Project net op zee Hollandse Kust (zuid)
The Hollandse Kust (zuid) offshore wind farm is located 22 kilometres off the coast of the Dutch province of Zuid-Holland. The sea cables connect the two offshore platforms with the Maasvlakte high-voltage substation and the Randstad 380 kV South ring. The wind energy is then fed into the national high-voltage grid to the electricity consumers in the Netherlands. In 2018, TenneT commissioned the Van Oord-Hellenic Cables consortium to build the offshore connection for the net op zee Hollandse Kust (zuid) project. The consortium will install and bury the sea cables that cross the entrance to Europe’s busiest freight port, the port of Rotterdam. The 1,400 MW grid connection will be completed in 2022 and will eventually provide electricity for 1.6 million households. The offshore wind farm contributes significantly to the Dutch government’s objective of having a total of 3.5 GW installed offshore wind energy capacity by 2023. With the commissioning of Borssele Alpha and Beta this year, the first 1.4 GW has been realized.

Offshore wind until 2030
After Hollandse Kust (zuid) Alpha and Beta the next project of the offshore grid will be the connection of Hollande Kust (noord). TenneT uses the same type of 700 MW transformer platform five times for the grid connection. The platforms are located close to the offshore wind farms. The offshore cable is also five times the same type of 220kV cable connection. This standardization enables TenneT to build these projects more efficiently, faster and cost-effectively. TenneT will realize another 6.1 GW of high-voltage connections for wind farms in the Dutch North Sea until 2030. In the German North Sea TenneT has already realized 7.1 GW and the capacity of TenneT’s offshore grid connections in Germany will be increased to approximately 17 GW in 2030.

Image source: Courtesy of TenneT

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