Cable landing for BorWin4 and DolWin4
Undercrossing of the island of Norderney

In 2030, the wind farms at sea are expected to provide as much electrical energy as 25 large coal-fired power plants. This enormously high amount of energy must be transported to the mainland with low losses and fed into the German electricity grid. For this purpose, the cable routes must cross under the island of Norderney in order to be able to land in the coastal area of Hilgenriedersiel.
This complex project is being carried out by the Ludwig Freytag Group on behalf of the transmission grid operator Amprion. The island crossing itself is carried out using the resource and environmentally friendly HDD ("horizontal directional drilling") method. In two sections, two boreholes each will be drilled from the centre of the island in the direction of the north and south beaches, into which the protective pipe strings for the subsequent cable laying will be pulled. For the first construction phase, two pipe strings of 1,100 m each were welded together on the south beach, brought to the north side of the island by tugboat and then pulled into the bore channel from the starting pit in the middle of the island. In further construction phases, the protective pipes between the centre of the island and the south beach as well as from the south beach under the tidal flats to the mainland will be installed in the same procedure.
Taking into account the expected intensive stress on the pipe wall during trenchless laying, the long installation length of the individual pipe strands and the high operating temperatures in the cable routes, the project partners decided to use the high-temperature-resistant E-POWER cable conduit system from Gerodur. Already in the planning phase, the technical staff of the Saxon company assisted in the ion of an optimal pipe material and actively supported the welding and laying services on site.