To maintain stable grid operation with widely fluctuating power infeeds from wind and solar sources, balancing power must be supplied. For this purpose, the client is planning an innovative project at a run-of-river hydropower plant on the River Weser for sourcing primary balancing power from a battery storage facility. The power output of this facility is specified as up to 5 MW. During the concept phase Fichtner assisted in the design of the tie-in of the energy storage facility at the power plant site and in preparations to obtain the required permits. Subsequently, Fichtner supported the client's application for a grid connection.