Hydrogen fuel cell systems
Hydrogen fuel cell systems generate electrical power onboard railway vehicles operating on non-electrified European lines by combining hydrogen with atmospheric oxygen through an electrochemical reaction, producing electricity, heat, and water without combustion emissions.
A proton exchange membrane (PEM) fuel cell stack receives hydrogen stored at high pressure — typically 350 bar in current rail deployments — and oxygen from intake air. The electrochemical reaction generates DC electricity.
Because fuel cell output varies with load and cannot respond instantly to traction demand, rail hydrogen systems pair the fuel cell with a lithium-ion buffer battery. The fuel cell operates at a relatively steady output to charge the battery and meet steady-state demand; the battery handles acceleration peaks and absorbs regenerated braking energy.
Hydrogen storage on rail vehicles uses composite pressure cylinders mounted on the roof or underframe. The Alstom Coradia iLint carries two roof-mounted tanks of 94 kg each — 188 kg total — and achieves a range of approximately 1,000 km per fill in its production configuration.
The Siemens Mireo Plus H uses 180 kg at 350 bar; at its December 2024 entry into service with Niederbarnimer Eisenbahn, Siemens specified an operating range of up to 1,200 km for the two-car configuration.
European deployment
The Coradia iLint entered commercial passenger service in Lower Saxony in 2018, operated by evb (Eisenbahnen und Verkehrsbetriebe Elbe-Weser). From 2022, fleets of 14 trains in Lower Saxony and 27 in the Taunus network north of Frankfurt entered scheduled service. Intensive operation identified reliability limitations; Alstom withdrew most of the Taunus fleet in December 2024 for overhaul, fitting new-generation fuel cells, with replacement diesel units covering services during repair.
Siemens Mobility delivered seven Mireo Plus H units to Niederbarnimer Eisenbahn for service north of Berlin, entering service in December 2024. Hydrogen supply disruptions led to temporary suspension within weeks of launch.
Both programmes experienced difficulties with hydrogen supply-chain reliability, which has constrained operational performance independent of vehicle technology. Stadler’s FLIRT H2 set a Guinness World Records distance mark of 2,803 km on a single fill during a March 2024 test at the ENSCO facility in Pueblo, Colorado.
Alstom acquired Cummins’ rail-focused hydrogen fuel cell operations on 2 April 2026, integrating the fuel cell technology developed with Hydrogenics into its own production chain.
Regulatory framework
IEC 63341-1:2025 applies to fuel cell power systems installed on rolling stock. The wider safety framework for onboard hydrogen systems encompasses pressure vessel standards and EN 45545 fire safety requirements.
The European Commission’s Hydrogen and Fuel Cells Technology Joint Undertaking (now part of Clean Hydrogen Partnership) has co-funded development programmes including the FCH2Rail project involving CAF and other manufacturers.