Offshore grid connection Borssele Beta ready to land offshore wind power

TenneT received the ‘Grid Readiness’ certification from DNV GL for Borssele Beta. This means that this offshore grid connection complies fully with the conditions set out in the so-called Offshore Wind Energy Development Framework. Marco Kuijpers, TenneT' s Director offshore activities: “We are proud of the fact that the second part of the Borssele high voltage connection is already complete and was realised within budget. Despite all the Covid-19 challenges, we were successful in continuing with the works; a huge achievement from all the contract parties involved.”  

Important step in energy transition

The Borssele III, IV and V wind farms will have a total capacity of 700 megawatts (MW), which is equivalent to the electricity consumption of around 1 million households. The electricity generated by the wind turbines is collected at sea at a transformer platform (“wall socket”). The voltage is converted from 66 kV into 220 kV. The electricity is then transported to land via cables in the seabed and is landed at an electrical substation at Borssele. At this station it is converted into 380 kV. Finally, the electricity is transported to the high voltage grid. TenneT is investing in upgrading the 150 kV grid in Zeeland and the 380 kV connection between the Borssele and Rilland high voltage substations to secure the transport of higher volumes of sustainable energy in the future.

Schematic presentation offshore grid (Image: TenneT)

Offshore schematic presentation offshore gridwind energy to 2023

By the end of 2023 TenneT will 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. It will then be the turn of Hollandse Kust (zuid) Alpha and Beta, 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 connection to the coast. Such standardisation enables TenneT to complete these projects more efficiently, more quickly and more economically.

Offshore Grid Programme 2024-2030

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 efficient 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.

Offshore grid connections Germany

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