Design space exploration of fuel Cell–Battery architectures for regional hydrogen trains under partial electrification

This study presents a reproducible, infrastructure-aware, model-based methodology for sizing hybrid hydrogen–battery powertrains for regional trains operating on routes with partial overhead line electrification (OHL). A physics-informed PEM fuel cell model was developed and validated against experimental measurements from a commercial 30 kW stack, achieving mean absolute percentage deviations below 5% for both voltage and efficiency. The validated fuel cell model was integrated into a vehicle-level simulation framework to perform a design-space exploration of ninety powertrain configurations (fuel cell: 120–360 kW; battery: 100–300 kWh) under multiple operating scenarios. Results show that optimal sizing is infrastructure-dependent: for fully non-electrified operation, a 360 kW fuel cell with a 100 kWh battery meets the operating constraints, whereas with partial OHL electrification a 120 kW fuel cell combined with a 300 kWh battery is preferable, reducing hydrogen consumption by more than 70%. Overall, the proposed workflow links component sizing, supervisory constraints, and route electrification within a consistent system-level assessment, supporting hydrogen trains as electrification gap-fillers rather than direct diesel substitutes.