OREANDA-NEWS.   Because wind is by nature intermittent, integrating wind power into power supplies is a challenge. From now on, one of Europe’s largest hybrid batteries will store the electricity generated at a community wind farm in the northern German municipality of Braderup and feed it back into the power grid as needed. Bosch and the community wind farm run by BWP Braderup-Tinningstedt GmbH & Co. KG together brought the stationary energy storage facility on stream on July 11, 2014.

Bosch designed and built the hybrid system, which has a total capacity of 3 megawatt hours (MWh). Comprising a 2 MWh lithium-ion storage unit and a 1 MWh vanadium redox flow battery, the energy storage plant operates with electronic controls and software specially developed by Bosch.

Speaking at the launch, Dr. Stefan Hartung, a member of the board of management of Robert Bosch GmbH, said: “This energy storage facility allows the supply of wind power to continue even when the wind stops blowing, and as such is an important building block on the way to a sustainable and viable energy system.”

Via an underground cable some 10 kilometers long, the hybrid storage facility is connected to the power grid run by Schleswig-Holstein Netz AG. Whenever the power grid on Germany’s windy North Sea coast is unable to absorb any more electricity from the wind turbines, the batteries step in and store the electricity ready for it to be released later, when the wind has dropped. There is therefore no need to shut down the wind farm or turn its turbines out of the wind when the grid is overloaded. What’s more, there is less need for new power grids.

A week’s worth of electricity for 40 homes
The double battery can store energy over the short and long term. “This system gives us the freedom to balance out the short-term fluctuations in output that are part and parcel of wind power generation,” said Jan Martin Hansen, managing partner of the community wind farm run by BWP Braderup-Tinningstedt GmbH & Co. KG. Depending on the strength of the wind and the battery’s state of charge, the control unit developed by Bosch distributes the power generated by the turbines to the most suitable battery type. With its overall peak power output of 2,325 kilowatts, the Braderup hybrid battery is capable of storing enough power to cover the electricity needs of 40 single-family homes for a week.

Working together for stable power grids
While the 200 private investors in the community wind farm financed its six 3.3 megawatt wind turbines, the hybrid storage facility is financed and operated by the joint venture Energiespeicher Nord GmbH & Co. KG. Bosch developed the battery control technology. Besides the batteries and control electronics, Bosch is also responsible for system integration and for testing different operating variants in Braderup. These include not only using part of the stored power for the wind farm’s own consumption and to stabilize power grids, but also marketing the power in the frequency regulation market and trading on the electricity exchange. The 200 investors and Bosch are the sole source of finance for the project. It is neither state-subsidized, nor does it receive any tax subsidies.