A model of the Siemens wind turbine SWT-3.6-120 which is installed at the DanTysk offshore wind farm.
TenneT laid the sea cable grid and constructed a new substation in Büttel for transmitting power from offshore wind farms.
The wind farm is located in the North Sea Economic Zone, near Sylt island.

DanTysk offshore wind farm is a 288MW power project located in the North Sea, 70km west of the island of Sylt in northern Germany. It was a collaborative project by Vattenfall and Stadtwerke München (SWM) through a joint venture called DanTysk Offshore Wind.

Vattenfall holds 51% stake and is responsible for the construction and maintenance of the offshore wind farm facilities. The remaining 49% stake is held by SWM. The project cost more than €1bn.

The wind farm produced its first power to the German electricity grid in December 2014. Formal commissioning of the project was held in April 2015. Green electricity produced by the wind farm will be sufficient to power more than 400,000 houses at an average consumption rate of 2,500kWh per home a year.

Development of DanTysk offshore wind farm

In 2007, Vattenfall acquired the DanTysk project from the previous developer Geo Gesellschaft für Energie und Ökologie. In July 2010, Stadtwerke München formed a joint venture with Vattenfall by purchasing 49% stake in the project.

“Construction of the DanTysk offshore wind farm started in March 2012.”

Vattenfall carried out the project to achieve its long-term goal of generating electricity from offshore wind farms. SWM undertook the project with the aim of powering 800,000 households in Munich with renewable energy.

DanTysk wind farm make-up

The DanTysk offshore wind farm spans an area of approximately 71km² in the sea. It has 80 turbines, each with a rotor diameter of 120m and capacity of 3.6MW. The turbines are built at depths ranging between 21m and 31m.

Contractors involved with DanTysk project

Siemens Energy supplied its SWT-3.6-120 model wind turbines for the project under a contract awarded in October 2010. It was also responsible for installing and commissioning the turbine units, as well as continuing to maintain them.

In December 2010, a turnkey contract was awarded to a joint venture of Strukton Systems and Hollandia for supplying the 155kV/33kV offshore transformer substation for the wind farm. The consortium was selected through a European-wide competitive tendering process. Seaway Heavy Lifting acted as a subcontractor to the consortium.

The Aarsleff Bilfinger Berger joint venture was awarded the design, production and installation contract of the 80 monopile foundations for the wind farm in April 2011.

The jacket/topside substation has three decks, a tank station and a helicopter landing pad. It was installed in 2013.

“The DanTysk offshore wind farm spans in 71km² of surface area in the sea.”

In February 2011 DanTysk Offshore Wind signed an agreement with the Danish shipping company Swire Blue Ocean (SBO) to use its heavy-lift vessel for transporting the wind turbines from Esbjerg seaport, Denmark, and installing them at the project site.

The 161.9m-long vessel has a 1,200t capacity, twin-hook crane and a helipad. The ship, Pacific Orca, was built at the Samsung Heavy Industries shipyard in South Korea.

It was delivered in 2012 and the wind turbines were preassembled at the Port of Esbjerg. The environmental standard requirements of the Pacific Orca are certified by GL-Group Germanischer Lloyd.

Grid network

Power produced at the wind farm is transmitted to a new onshore substation built in Büttel, Schleswig-Holstein by the German-Dutch distribution grid operator TenneT.

TenneT operates an offshore platform called SylWin alpha in the North Sea. The platform is connected to the onshore electricity grid network by a 160km sea cable and a 45km land cable to the new substation in Büttel, Schleswig-Holstein.

Distribution of DanTysk offshore wind plant

The AC power generated by the 80 wind turbines at the DanTysk offshore wind farm is collected by the offshore transformer substation. It is connected to the high-voltage direct current (HVDC) converter station SylWin alpha.

The AC is converted into HVDC and then transmitted to the onshore Büttel station via the cable network. This avoids transmission losses. The onshore converter station converts the DC back into AC. The electricity is then distributed through the national ultra-high-voltage electricity grid.


Construction of the DanTysk offshore wind farm started in March 2012. Offshore construction work began in February 2013 and all of the 80 foundations were installed by December 2013. Turbine installation began in March 2014 and was completed by the end of 2014.

Construction of an offshore accommodation platform for the employees serving at the wind farm began in 2015.

NRI Energy Technology