RWE has announced that it will offer a secondary reserve for system stabilization to balance the German grid through its 302 MW offshore wind farm, Amrumbank West.

This is the first time that an RWE offshore wind farm provides this service, also known as automatic frequency restoration reserve, which keeps the grid frequency stable at 50 Hz, preventing potential grid failures.

When frequency fluctuations occur in any part of the grid, the relevant transmission system operator requests compensation energy to counterbalance and correct the imbalance. The required capacity for this is auctioned daily by the transmission system operator.

To participate in secondary reserve auctions, the power offered by a participant (in this case, the reduction of 60 MW in the wind farm’s capacity) must be fully activated within five minutes.

In practice, the Amrumbank West offshore wind farm must be able to reduce its power in a matter of seconds; this is done by adjusting the rotor blade position, thus moving them away from the wind with millimeter precision.

This requires appropriate processes and technology for the wind farm’s control systems, which can react ad hoc to short-term wind fluctuations while also taking into account current wind forecasts. For this reason, RWE has developed a highly automated and scalable infrastructure to balance wind power; this includes the control system provided by its partner Generac Energy Services.

According to the company, starting from the first quarter of 2025, it will market this secondary reserve through daily balancing energy auctions. From that point, the offshore wind farm off the German North Sea coast will not only supply green electricity but will also actively contribute to the stability of the German electrical grid. Located about 37 kilometers west of the island of Amrum in North Frisia, the Amrumbank West wind farm has 80 turbines.

RWE has extensive experience in the commercialization and provision of balancing reserves for grid stabilization from various types of assets (such as pumped storage, gas-fired power plants, and more recently, batteries).

By providing balancing reserves from wind energy, the company is venturing into a new field. Market participants are remunerated by the transmission system operator for providing secondary reserves as well as for actual supply.