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 H₂ production 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 H₂ core 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 gridcongestion-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 H₂ production 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.