Vattenfall - The construction

The construction

• First, the foundation was placed. It is a cylindrical steel pipe with a diameter of about 4 metres. A pile driver placed on a barge, stabilized by legs, ramed the pipe approximate. 25 metres into the seabed.
• Then, the wind turbines was mounted by means of large specially built vessels with submersible legs. A crane on the vessels lifted the turbines into place.
• The wind turbines were connected via submersible cables to the offshore transformer substation which will collect the power.
• Via a submarine cable, the substation is connected to the onshore power transmission grid.

Constructing a turbine foundation

In the Horns Rev project, the so-called "mono-pile" concept was used, single piles that are driven into the seabed. Pile driving is a fast process, and piles are relatively inexpensive to produce. Geotechnical surveys show that the seabed was made up of sand, and this makes mono-pile foundations particularly attractive. Mono-pile foundations have also been used for offshore turbines in the Netherlands and Sweden. Similarly, the projects meteorological tower rests on a mono-pile foundation. The foundation is designed as a cylindrical steel pipe with
a diameter of approximate 4 m and a material thickness of 5 cm. A large, hydraulic ram drives the steel pipes into the seabed to a depth of some 25 meters. A "mattress" of gravel is placed around the foundation to protect against erosion.