TenneT awards HVDC contracts for North Sea wind farms

March 3, 2023
TenneT has appointed NKT and Prysmian to supply and install five 525-kV XLPE HVDC cable connections for five Dutch 2-GW wind farm developments.

Offshore staff

ARNHEM, the NetherlandsTenneT has appointed NKT and Prysmian to supply and install five 525-kV XLPE HVDC cable connections for five Dutch 2-GW wind farm developments in the Dutch North Sea, for completion between 2028 and 2030.

NKT will deliver the cable connections for IJmuiden Ver Beta, IJmuiden Ver Gamma and Nederwiek 2, landing onshore at Maasvlakte in the port of Rotterdam.

Prysmian will perform the cable connections for IJmuiden Ver Alpha and Nederwiek 1, landing onshore at Sloegebied in Zeeland province.

The work scope for both contracts includes design, engineering, production, delivery and project management; offshore, nearshore and inshore installation of 525 kV HVDC cables; and all jointing of submarine and land sections.

Activities should start this year, with offshore cable laying due to get underway in 2026.

For the tender, TenneT asked the suppliers to achieve substantial CO2 and NOx emission reductions, and to use recycled copper. To improve safety, the cable suppliers will invest in new production capacity, vessels and trenching tools (when needed).

A 2-GW direct current (HVDC) solution, based on 525 kV, requires only one cable system, comprising four cables, a 'plus' and 'minus' pole cable, a metallic return cable and a fiber-optic cable.

In 2020 TenneT and various companies began an R&D initiative for the development. Transporting the required 2 GW of power, an offshore cable system operating at 525-kV HVDC involves use of extruded insulation.

A concurrent design and layout study for a generic offshore platform, allowing for inter-operability of the proprietary solutions offered by all HVDC suppliers participating in the R&D phase, led to certification of cable suppliers in 2022.

Prysmian Group, commenting on its €1.8 billion ($1.91 billion) contract, said the IJmuiden Ver Alpha offshore grid connection system would be about 164 km long, with a further 12 km onshore. Nederwiek 1’s total route length is roughly 217 km (208 km offshore).

Each cable system will feature two single-core 525 kV HVDC cables (with XLPE insulation for the submarine portion and P-Laser insulation for the land route), one single-core metallic return cable and one fiber-optic cable.

The company will manufacture the submarine cables in Pikkala, Finland and Arco Felice, Italy, and the land cables in Gron, France. Prysmian cable-lay vessels will handle marine installation operations in partnership with DEME Group.

Last year the company completed development and testing of its first 525-kV extruded submarine full cable system for HVDC applications.