Cycling Constraints Matter: Modelling Operational Limits of Underground Hydrogen Storage

Underground hydrogen storage (UHS) is expected to play a key role in long-term balancing of future renewable hydrogen-based energy systems. However, large-scale energy system models often oversimplify the operational behaviour of geological storage. This study investigates the impact of cycling constraints on the deployment and utilisation of UHS using the PyPSA-Eur energy system model. Results show that cycling constraints strongly influence both the optimal allocation and operational profile of UHS. Installed UHS capacity increases to 116-121 TWh, with depleted fields providing seasonal flexibility, while salt caverns exhibit more monthly cyclic behaviour. Cycling limitations of UHS increase the need for fast-response overground storage. These findings highlight the importance of representing operational constraints in energy system models and provide insights for planning resilient hydrogen storage infrastructure in Europe.