Technical Details

Construction site

The planning region for Nordsee Ost is around 30 kilometres to the north of Helgoland Island and around 35 kilometres west of the North-Friesian island of Amrum. The site is outside the main shipping lanes, military exercise areas and seabird protection zones. Ground drilling investigations encountered almost exclusively sand. This means the substrate is excellently suited to the construction of wind turbines. The wind farm will cover an area of around 24 square kilometres, with water depths of 22 to 25 metres.

Installation concept

For the installation of the 48 turbines of the Nordsee Ost wind farm, RWE Innogy constructs one of the world’s biggest construction vessels. This special vessel can transport and install up to four multi-megawatt turbines including their foundations. Despite its length of over 100 metres and a width of around 40 metres, this vessel can be positioned with centimetre-precision through satellite guidance for the construction work at sea and can work in water depths of over 40 metres. RWE Innogy has commissioned another identical construction vessel for the installation of the Welsh offshore wind farm Gwynt y Môr. The order value for each construction vessel is around EUR 100 million.

Operation & maintenance

Due to the size of the individual components, the local weather conditions and, of course, the large distances, maintenance of offshore wind farms is difficult and expensive. In poor weather conditions, it may not be possible to access an offshore wind farm for several days with the result that repair and maintenance work cannot be performed. Therefore, it is crucial to develop a good maintenance and operating concept for our own plants.

In the first five operating years, the plant manufacturer REpower will have overriding responsibility for the operation and maintenance of the Nordsee Ost wind power plants. RWE Innogy will use this time to learn from REpower so that it can then take on the operation and maintenance of the wind farm itself.

Foundation structure

Compared with other offshore projects, the Nordsee Ost wind farm is to be installed in very deep water. Due to the water depth of up to 25 metres and the high loads of the new 6 megawatt turbines, the jacket foundation proved to be the most feasible solution for anchoring the wind turbines in the sea bed.

Jacket foundations have a similar design to conventional high voltage masts. Steel pipes form a spatial framework. The jacket is anchored with pillars at all four feet. This design means jackets are especially well suited to installation in very deep water.

Meteo tower

To be able to check the total output of the wind farm as well as the individual output of each individual turbine, RWE Innogy has install a metering mast in the wind farm.

This will supply output-specific comparison data which will be used to optimise the technical configuration of the individual turbines.