Eurotech Benelux, Jan de Nul to Manufacture Anchor Cages for Swedish Offshore Wind Farm

Eurotech Benelux has teamed up with Jan de Nul Group for the winning bid to design and manufacture sixteen anchor cage structures for a major offshore wind farm.

The wind farm, in the Swedish region of the Baltic Sea, will be owned and run by E.ON Sweden. Eurotech Benelux is creating the anchor-bolted cages to support the gravity-based foundations of the 3 megawatt wind turbines.

The cages were co-developed by Eurotech Benelux. They consist of two flanges secured by 160 M36 anchors. Each cage is 4.5 meters in diameter by 3 meters high, and weighs over 8,000kg. Besides the steel fabrication and anchors, Eurotech Benelux is also responsible for the assembly of all cages on site in Zeebrugge (Belgium), before they are casted in.

The concrete foundations, each weighing 1,800 tons, began construction in March 2012. By completion it will have taken four months to pour 10,000m³ of concrete into the 24.5m deep foundations, which are hollow concrete structures with a base diameter of 18m. The foundations are towed from Zeebrugge to Sweden from May 2012 on large pontoons.

At the installation site, a vessel will dredge a pit in the seabed down to a sufficient bearing capacity of the subsoil, upon which a rock layer will be placed by a stone-dumping vessel. The wind turbine foundations will be installed onto the rock layer and ballasted with sand. They will be protected with rocks against wave action, which will last up to 50 years before needing to be replaced.

The wind turbine generators are Vestas V112s with 112m rotor diameter. When fully operational the wind farm will provide green power for up to 50,000 families.

Work is expected to finish by the autumn of 2012.

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Offshore WIND Staff, July 18, 2012; Image: Eurotech Benelux