The decarbonization of regional rail remains a pressing challenge in the European Union, where nearly half of the 200,000 km network remains unelectrified. Lightweight, single-car railbuses historically provided efficient service on such lines, but modern replacements are scarce. This work evaluates a standardized 30-ton, 16 m railbus platform for unelectrified regional service, focusing on propulsion system design and trade-offs between range, cost, and emissions.
A MATLAB/Simulink drive-cycle model was developed to simulate energy consumption under realistic operating conditions. The Erfurt–Rennsteig route in Germany (130 km round trip, gradients up to 6 %) was selected as a representative case study. The model incorporates sub-models for traction motors, lithium-ion batteries (LFP and LTO), fuel storage, fuel cells, and ICE gensets across multiple fuel options (diesel, gasoline, methane, ethanol, methanol, HVO, FAME, and hydrogen). Battery lifetime is estimated using a combined cycle- and calendar-aging model using the rainflow algorithm for cycle extraction.
Results show battery-electric configurations achieve ~1 kWh/km energy use, while hybrid systems consume 2–4 kWh/km depending on fuel and power unit. Control strategies that enable deeper battery cycling reduce fuel consumption by 7–18 %, with further savings possible from larger battery or genset capacities. Well-to-wheel greenhouse gas emissions range from -1.2 kg/km to 3.9 kg/km. Lifecycle cost analysis indicates that while fuel may account for up to 25 % of costs, track and station fees dominate. Autonomous operation could reduce staffing costs by 25–35 %.
This study demonstrates that lightweight battery-electric and hybrid railbuses are technically viable for low-demand regional lines. The choice of propulsion architecture is strongly influenced by local energy context, infrastructure charges, and policy incentives. The simulation-based methodology facilitates the comparison of drivetrain options, supporting the design and deployment of sustainable small regional rail vehicles in Europe.