On the right track: Cost-optimal choices to decarbonize the European railway network

As Europe accelerates toward climate neutrality, the phase-out of diesel trains creates an urgent need for cost-effective alternatives on non-electrified railway lines. With over 40% of the network still lacking electrification, regional services face a critical decarbonization challenge. This study introduces a geospatial techno-economic framework to identify cost-optimal strategies for regional passenger rail, integrating high-resolution network data, demand estimation, lifetime costs modeling, and emissions assessment. Three archetypes emerge: (i) short low-traffic lines favor battery; (ii) long low-traffic lines favor hydrogen, provided that hydrogen prices decline to approximately €5–6/kg; and (iii) dense high-traffic lines favor electrification. The results indicate that no single propulsion technology can simultaneously minimize costs across heterogeneous line conditions. In particular, a single-technology strategy leads to significant economic penalties, increasing Total Cost of Ownership by 10–30%. Furthermore, under the cost-optimal configuration, well-to-wheel carbon emissions can be reduced by up to 90% compared to a diesel-only baseline. Overall, the analysis demonstrates that only a diversified technology mix can ensure a successful and economically sustainable transition toward zero‑carbon regional rail.