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.