TenneT picks Asso.subsea for 2 GW cable installation work in Germany

Asso.subsea has been awarded a nearshore cable installation contract for three projects under TenneT’s 2 GW program in Germany.

The offshore grid connection projects—BalWin4, LanWin1, and LanWin5—are situated off the northwestern coast of Baltrum Island in northern Germany. This contract initiates a new partnership with Jan De Nul as the primary contractor, while TenneT, the German transmission system operator (TSO), serves as the end client. Each project entails transporting and installing a nearshore cable bundle consisting of two HVDC power cables, one metallic return cable, and one fiber optic cable. Cable transport will originate from load-out ports in either the Netherlands or Germany, with nearshore installation carried out by the cable-laying vessel Atalanti. The work scope also includes precision cable landings using beaching operations with spud cans, free-lay installation in intertidal areas, and wet storage of cable ends. Installation is scheduled to take place in phases: BalWin4 in 2027, LanWin1 in 2028, and LanWin5 in 2029.

Steel cutting for BalWin4, Germany’s first 2 GW offshore grid connection, began in March 2025, marking a major project milestone. BalWin4 is scheduled for commissioning in 2029, followed by LanWin1, which will undergo fabrication, installation, and commissioning a year later, with completion targeted for 2030. A consortium comprising Jan De Nul, LS Cable, and Denys is responsible for delivering the cable connections in Lower Saxony: BalWin4 and LanWin1 will link to the grid in the Unterweser area, while LanWin5 will be connected near Rastede. The commissioning of LanWin5 is planned for 2031.