Energinet.dk and 50Hertz Transmission GmbH have awarded Iemants and Jan De Nul Group with a contract to construct, install, ballast and protect gravity based foundations (GBFs) for two offshore substations.
The two offshore substations will serve Vattenfall's 600MW Kriegers Flak offshore wind farm in the Danish part of the Baltic Sea, and will also serve as an interconnector between the Danish and German power net.
The interconnector project is funded by the European Energy Programme for Recovery.
Kriegers Flak consists of two sections, each with its own substation. Kriegers Flak A, the west section, will have a total capacity of 200MW. The east section, Kriegers Flak B, will have a total capacity of 400MW.
Jan De Nul Group is in charge of the design, construction, transport and installation of the GBFs, whereas Iemants will take care of the detailed design, fabrication and transportation of the steel shafts and decks which will be placed on top of the GBFs. The steel structures will be (pre)fabricated at the Iemants’ facilities in Belgium.
The GBFs will be constructed on a pontoon based in the port of Zeebrugge, Belgium, and towed to the Baltic Sea.
In Denmark, Jan De Nul’s backhoe dredger Gian Lorenzo Bernini and the fallpipe vessel Adhémar de Saint-Venant will take care of the excavation of the foundation pit and installation of the gravel bed.
Once the pontoon with GBFs arrives in Denmark, it will be immersed to offload the structures upon which the foundations will be installed onto the gravel bed. Finally, the GBFs will be ballasted and protected through scour installation by means of the Adhémar de Saint-Venant.
The GBFs shall be installed offshore by the end of 2017, and the wind farm is expected to be operational by 2022, providing Danish households with the world's cheapest energy generated by offshore wind turbines.