Flexible electrolysers as a tool for renewable energy integration and congestion management: comparison of different allocation methods in a transmission system case study for Germany 2030

The integration of renewable energy sources (RES) into future power systems necessitates increased flexibility. At the same time, the hydrogen (H₂) market in Germany and Europe is expected to rapidly expand, including a substantial increase in domestic H₂production via electrolysis. Flexible electrolysers and hydrogen power plants can support RES integration and play a pivotal role in grid congestion management (redispatch), which is highly sensitive to the units’ locations. In this study, we compare three electrolyser allocation methods — driven by hydrogen demand, nodal renewable energy surplus, or an optimization that minimizes line overloading — across the German transmission system for the year 2030. Using detailed models of the power system and the planned H₂core network in Germany, and hourly time-series data from an energy system optimization, we analyse redispatch volumes and costs associated with each allocation method. The findings of our case study reveal that a grid-congestion-minimizing approach lowers redispatch volumes by around 36% and redispatch costs by around 34% compared to a hydrogen demand-oriented allocation. Additionally, allowing electrolysers to participate in redispatch further decreases redispatch costs by 4–10%. While this causes an increase of the electrolysers’ electricity consumption and H₂production by 13–14%, the RES curtailment is reduced by 7–29%. These results underscore the strategic value of electrolyser placement and flexibility in congestion management for efficient power system design and operation in a renewable-dominated energy landscape.