Marine engineering group Jan De Nul has completed its 2025 transport and installation campaign for three high-voltage alternating current (HVAC) export cables at TenneT’s DolWin kappa offshore grid connection platform, the company said.
The campaign involved the installation of around 37 km of 155-kilovolt cable, which will transmit nearly 660 megawatts of electricity from the Nordseecluster 1 and 2 offshore wind farms to the DolWin kappa platform, Jan De Nul said.
The work was carried out in partnership with Hellenic Cables and covered the design, manufacture, transport, installation and protection of the export cables. Cable-laying vessel Isaac Newton installed the three links between the platform and the two wind farm sites, with concrete mattresses placed at subsea crossings.
According to Jan De Nul, the multi-purpose vessel Adhémar de Saint-Venant subsequently buried the cables using its UTV1200 trencher. Protection works were completed by rock installation vessel Simon Stevin, which placed around 25,000 tonnes of rock berms over a two-week period, marking the end of the 2025 offshore campaign.
“Rock installation vessel Simon Stevin placed about 25,000 tonnes of rock berms over the past two weeks to protect the cables, concluding the 2025 campaign,” the company said.
Connection and testing activities are scheduled for 2026, following the installation of the Nordseecluster offshore substations.
Jan De Nul said the wider DolWin6 project will connect Nordseecluster 1 and 2 and the Gode Wind 3 offshore wind farm to the onshore grid, with a combined capacity of 900 MW. The company added that additional export cable projects are planned as part of its long-term service agreement with German grid operator TenneT.
