Decarbonizing rail transport with green hydrogen: Techno-economic and environmental insights into alternative propulsion systems

• Hydrogen fuel cell trains are assessed on regional rail lines. • Hydrogen and diesel trains are compared to rail electrification. • Hydrogen trains operation costs 5.14 million euros/year, lower than electrified lines. • Hydrogen trains cut 6,142 t CO 2 /year, while electrification cuts 7,160 t CO 2 /year. • Hydrogen trains offer strong economic and environmental benefits on low-demand routes. Meeting the European Union’s decarbonization targets requires a rapid transition of railways to low-emission propulsion, particularly on non-electrified lines where diesel traction remains prevalent. This study investigates green hydrogen fuel cell trains (H 2 -FCTs) as an alternative to direct electrification and conventional diesel for regional passenger rail in Portugal. Their feasibility, cost-effectiveness, and environmental performance are evaluated across four representative railways, considering green hydrogen production and refueling, as well as operational parameters such as route length and service frequency. The techno-economic assessment shows annual operational costs of 5.14 M€ (0.091 €/passenger-km) for the H 2 -FCT scenario, compared with 18.12 M€ (0.32 €/passenger-km) for the fully electrified lines. From an environmental perspective, the life cycle analysis demonstrates that both scenarios achieve substantial reductions in greenhouse gas emissions relative to diesel operation, with the H 2 -FCT scenario avoiding 6,142 t CO 2 annually (0.109 kg CO 2 per passenger-km), while electrification achieves a further reduction of 7,160 t CO 2 per year. Although both electrification and hydrogen propulsion represent viable decarbonization pathways, hydrogen fuel cell trains demonstrate greater combined economic and environmental advantages, particularly on low-demand regional lines. These findings underscore the strategic role of green hydrogen in advancing sustainable rail transport and guiding policy toward carbon–neutral mobility.