A methodology based on the depot selection to identify the non-electrified railway lines to be converted to hydrogen propulsion

Rail and metro systems are essential for sustainable mobility, offering higher passenger capacity with the same energy consumption and lower emissions compared to cars and buses. Railway propulsion currently relies on two main technologies: electric and diesel-powered systems. Electric trains produce no local emissions, though their overall environmental impact depends on the energy mix used for electricity generation. Diesel-powered trains use an internal combustion engine to generate electricity and drive the wheels via an electric motor, resulting in emissions directly linked to diesel combustion. The lack of electrification is often due to an unfavourable cost-benefit analysis, as secondary lines often have insufficient traffic to justify the investment. In this context, to enhance the sustainability of non-electrified railway lines, Italy’s National Recovery and Resilience Plan has allocated €300 million to test hydrogen-powered trains, selecting six lines and nine refuelling stations for conversion. Indeed, hydrogen may serve as an intermediate solution to full electrification, enabling a gradual transition from diesel with minimal infrastructure modifications. This paper presents a methodology for grouping railway lines that share refuelling stations to optimise hydrogen production, storage, and distribution costs. The approach is applied to the Italian railway network to evaluate feasibility and support the National Recovery and Resilience Plan objectives.