The offshore wind power plant, located 90 kilometres west of the island of Sylt, is now fully installed. On 21 January the installation vessel MPI Adventure together with Siemens erected the last turbine.
A total of 72 Siemens SWT-4.0 130 wind turbines in the 4 MW class were installed, providing a total capacity of 288 MW. Sandbank is the second joint offshore wind project for Vattenfall and SWM already. Together with the sister-project DanTysk (in full operation since early 2015) both wind power plants will provide a combined portfolio of 576 MW of installed generation capacity.
Offshore support vessel MPI Adventure - Image courtesy: Stan Laundon
The investment costs for the Sandbank offshore wind farm are around € 1.2 billion. Vattenfall holds a 51% stake in Sandbank Offshore GmbH, which was set up to implement the project, while Stadwerke München (SWM) holds a 49% stake.
When the wind farm is in full operation, an offshore substation will collect the wind energy of all 72 turbines, transform it from an AC voltage of 33 kilovolts (kV) to 155 kV, and deliver it to a converter station, from where the energy will be transported as DC over a distance of 165 kilometres to the landing point in Büsum, Schleswig-Holstein. The first Sandbank wind turbine was installed end of July 2016. Currently 65 of all 72 wind turbines deliver electricity from wind into the German electricity grid.
During the commissioning phase of the wind turbines a modified type of vessel including a “walk-to-work” gangway was deployed by the project for the first time in the German North Sea. This system equalizes the wave motions of the North Sea and features a special gangway that enables the commissioning teams to step over to the wind turbines directly, with sea conditions of up to 2.5 metres in height. The new concept also enables for work with enhanced safety standards and to be carried out 24 hours per day.
“We are very pleased that the installation of the wind turbines for Sandbank was running so successfully”, said Martin Zappe, technical Head of the project at Vattenfall. “The technology deployed on the project as well as the co-operation between all involved parties have gained a lot in terms of maturity. Projects of this size are now much more standardized and efficient. We will use these experiences for future projects to implement them as cost efficient as possible, also with regards to the new auction system for coming offshore projects in Germany.”
Christian Vogt, Head of Corporate Investment Management at Stadtwerke München commented: “Offshore wind power plays a key role to meet SWM’s ambitious targets for the expansion of renewable energy. By 2025, SWM is aiming to produce as much green electricity as required to power the entire city of Munich. Sandbank is SWM’s fourth offshore project, which is implemented successfully and even faster than originally scheduled. I would like to thank all those who contribute with their commitment to the success of this very complex project."