Bohlen & Doyen, a subsidiary of the German energy infrastructure construction company Friedrich Vorwerk Group, has signed a contract with French cable manufacturer Nexans to build the onshore cable connection for the BorWin6 offshore wind grid in Germany. The total volume of the order is in the mid-two-digit million range, according to a press release from Friedrich Vorwerk Group.
Nexans won the tender for BorWin6 cabling work last summer. Under its contract with TenneT, the company is responsible for the production and laying of cables, including those at the sea, tidal flat, and land.
The cable laying work is expected to start in 2025 and BorWin6, which will have the capacity to link 980 MW of offshore wind off the island of Borkum to the grid, is scheduled to go online in 2027.
BorWin6 will connect to the grid on land through an onshore converter station in Büttel, with the now-contracted Bohlen & Doyen tasked with installing the 45 kilometres onshore section from the landing point in Büsum, Schleswig-Holstein, to the future converter station in Büttel.
According to the German company, due to various dyke and watercourse crossings, as well as sensitive ecosystems along the onshore route, around 30 per cent of the underground cable connection will be realised using the latest trenchless horizontal directional drilling (HDD) technology.
The onshore cable will be installed parallel to the existing routes of the HelWin1+2 and SylWin1 connections, whose onshore converters are also located in Büttel.
Offshore, BorWin6 will be linked to the BorWin kappa platform via 66 kV three-phase cables, which eliminates the need for the transformer stations that were previously required in each wind farm and the 155 kV three-phase cables that were previously used to connect to TenneT’s offshore platforms.
The total cable route from the offshore converter station BorWin kappa to the substation on land is 235 kilometres long.