Approximately 4.5 months after the start of this installation campaign in January, Jan De Nul, Siemens Gamesa and Vattenfall deliver the 604 MW Kriegers Flak offshore wind farm.

Bert Reynvoet, Project Manager of Jan De Nul Group for the Kriegers Flak offshore wind farm: “Our project team, crew members on board the Vole au vent and all our partners involved did a fantastic job. Despite the winter weather conditions and extra challenges due to COVID-19, the works have always been on schedule, thanks to their efforts. Great teamwork! We are very proud to have helped Denmark in this giant leap in their energy transition.”

The Kriegers Flak offshore wind farm is the largest in Denmark and increases Denmark’s wind production by no less than 16 percent.

Challenging soil conditions for a Jack-Up vessel

The geographical location of the offshore wind farm offers extremely heterogeneous soil conditions with large lateral variability and boulders on the surface and below. Despite that, Jan De Nul managed to successfully deploy a Jack-Up Installation Vessel for the installation works.

Bert Reynvoet: “Thanks to elaborate preliminary geophysical and geotechnical studies and with the help of an in-house calibrated leg penetration model, we managed to engineer an efficient jacking procedure. This allowed us to execute the project ahead of schedule.”

Offshore high-voltage substations

In 2017 and 2018, Jan De Nul Group already designed, built and installed two large Gravity Based Foundations for the offshore high-voltage substations of this new offshore wind farm. Jan De Nul built both concrete structures of 8,000 and 10,000 tonnes on a floating pontoon in the port of Ostend (Belgium) and then towed them to Denmark. In the Baltic Sea, the crane vessel Rambiz installed both foundations on the seabed with the utmost precision.