Germany: Nordsee One successfully installs foundation of offshore substation

One wek ago the installation team successfully installed the foundation of the offshore substation at the Nordsee One construction site, located approximately 40 km north of the island of Juist. The foundation, which weighs more than 1,400 tons, traveled from Aalborg in Denmark; from there it was a five day journey across the North Sea, to the port of Eemshaven in the Netherlands. After loading the piling hammer, the foundation was transported to the Nordsee One construction site, where a floating crane placed the heavyweight jacket foundation onto the sea bed. The 50-meter tall foundation was anchored with four piles on the four pedestals in the bottom of the sea. Each pile has a weight of over 240 tons and a length of over 67 meters.

Tim Kittelhake, Managing Director (COO) of Nordsee One GmbH explained: “The offshore substation will comprise the upper part - the topside - with a weight of approximately 2,200 tons, and the lower part, the jacket foundation, we have installed on schedule yesterday – thanks to the strong cooperation between our team and partners”.

Pierre Lestienne, Managing Director (CFO) of Nordsee One GmbH added: “In June, we will begin the installation of the inter-array cables, and this summer we will install the heart of the wind farm, the substation topside. The topside is a steel building with four levels; it will house the grid transformers, switchgear and auxiliary power supply for lights, safety systems and data and control system.”

Floating crane

The offshore substation will transform the electricity generated by the 54 wind turbines at 33 kV to a transmission voltage of 155 kV. Submarine high-voltage cables then transmit the electricity to Dolwin Beta converter station of the grid operator where the AC voltage is transformed to 250 kV DC voltage and transmitted to the nearest grid access point at Hagermarsch. Once installed, the substation will be the nerve center of the Nordsee One wind farm. Bladt Industries has been awarded the contract for the design, fabrication, installation and commissioning of the offshore substation. They also has produced and delivered the jacket foundation.

The completed Nordsee One wind farm will consist of 54 wind turbines with an overall installed capacity of 332 megawatts. Once commissioned in 2017, the wind farm is expected to produce an annual output of more than 1,300 gigawatt-hours of electrical energy, enough to supply the equivalent of some 400,000 German households. Nordsee One is owned by Northland Power Inc. (85%) and RWE International SE (15%).