Tennet awards multi-billion contracts to connect 10GW of Dutch offshore wind

Tennet has awarded contracts worth €3.8 billion to NKT and Prysmian to install the world's largest offshore electricity transmission cable network for offshore wind.

An NKT high-voltage export submarine cable is loaded onto a laying vessel (Image credit: NKT)
An NKT high-voltage export submarine cable is loaded onto a laying vessel (Image credit: NKT)

The cables will connect five 2GW Dutch offshore wind farms to the country's national grid between 2028 and 2030.

Five 525kV XLPE high-voltage direct current (HVDC) transmission cables – especially developed for 2GW connections – will be installed to connect 6GW of Dutch projects planned for the IJmuiden Ver wind farm zone and 4GW for the Nederwiek Zone under the government’s offshore wind roadmap. 

The Netherlands aims for 21 GW of offshore wind by 2030 and tenders for the first 4GW, in Ijmuiden Ver, are due later this year. 

Further tenders for Ijmuiden Ver’s Sites V and VI (1GW each) are planned for 2025, with the project due online in 2029. 

Meanwhile, two 2GW tenders for Nederwiek are due in 2025 and 2026, with an online date of 2030.

Billion-euro contracts

Danish firm NKT will install the IJmuiden Ver Beta, IJmuiden Ver Gamma and Nederwiek 2 cable connections, all landing at Maasvlakte in Rotterdam. The contract, NKT’s largest to date, is worth approximately €2 billion.

Under a similar €1.8 billion contract, Italian company Prysmian is responsible for the IJmuiden Ver Alpha and Nederwiek 1 cable connections, landing in Zeeland’s Sloegebied. 

The contracts cover design, engineering, manufacturing, supply, project management, offshore, nearshore and inshore installation of the cables and all connection work in subsea and land sections.

Work is expected to start this year, while onshore cable laying will begin in 2025 and offshore cable laying in 2026. 

All connections are expected to be operational between 2028 and 2030.

Designed for the future

Under Tennet's plan for larger-scale offshore wind farms, power is brought to shore via a 525kV, HVDC connection using just one cable system to minimise impact on the environment. Onshore substations will link the wind farms to the national high-voltage grid. 

The tender featured high sustainability and safety standards, encouraging suppliers to minimise their environmental impact, by using recycled copper.

Tennet expects to announce similar contracts and framework agreements for a further 2GW of offshore cable connections in the Netherlands and Germany “in the coming months”. 

As the Netherlands’ designated offshore grid operator, Tennet is responsible for ensuring timely grid connections for around 20GW under its current mandate. It also has to prepare connections for another 20GW in German waters, although it is looking to sell its German grid business.

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