As Europe continues its transition towards cleaner and more sustainable mobility, hydrogen is emerging as one of the technologies that could help reduce the environmental impact of rail transport, particularly on lines where conventional electrification is difficult or economically challenging.
The EN IEC 63341 series on hydrogen and fuel cell systems for rolling stock provides an important standardization framework to support this development. Within Europe, this work is addressed by CENELEC/TC 9X ‘Electrical and electronic applications for railways’, building on international standardization carried out within IEC/TC 9 ‘Electrical equipment and systems for railways’, in cooperation with IEC/TC 105 ‘Fuel cell technologies’. CENELEC/TC 9X has a long-standing role in mirroring IEC/TC 9 work and providing European electrotechnical standards for the railway sector.
The EN IEC 63341 series provides a comprehensive framework covering three complementary aspects of hydrogen-powered railway vehicles.
EN IEC 63341-1:2025 addresses the fuel cell power system itself. It specifies requirements for proton exchange membrane fuel cell systems using hydrogen and covers their integration into different types of rolling stock, from trams and metros to regional trains, high-speed trains and locomotives. Attention is given to system architecture, interfaces, environmental conditions, performance, safety, reliability and validation. Safety requirements notably address hydrogen leakage, fire and explosion risks, electrical hazards and the behaviour of equipment under demanding railway operating conditions.
EN IEC 63341-2:2025 complements these requirements by addressing the on-board hydrogen fuel system. It covers gaseous hydrogen storage, fuel lines, pressure management, fuelling interfaces, monitoring and control systems, ventilation and emergency protection. Risk assessment, leak detection and safe pressure relief are central elements of the standard, helping manufacturers integrate hydrogen storage safely into railway vehicles.
EN IEC 63341-3:2026 establishes performance test methods for fuel cell power systems. Rather than defining mandatory performance levels, it provides harmonized methods allowing manufacturers, system integrators and railway operators to measure and compare systems consistently. Tests address areas such as output power, electrical efficiency, hydrogen consumption, start-up and shutdown behaviour, dynamic operation and performance under different temperatures, humidity levels and altitudes.
An alternative for non-electrified railway lines
The potential of hydrogen propulsion is particularly relevant for non-electrified routes currently dependent on diesel traction. Fuel cells generate electricity on board while producing water as their principal local emission, allowing hydrogen trains to operate without direct tailpipe CO₂ emissions or conventional diesel exhaust.
This can provide an alternative where installing overhead electrification infrastructure would be technically difficult or disproportionately expensive. The European Commission has already identified hydrogen fuel-cell trains as a possible solution for railway routes that are difficult or not cost-effective to electrify. More recently, the European Clean Hydrogen Partnership reported successful demonstration of hydrogen-electric hybrid trains on Spanish and Portuguese networks, highlighting their potential to replace diesel operation on non-electrified routes.
The environmental advantage nevertheless depends strongly on the origin of the hydrogen: using renewable or other low-carbon hydrogen maximizes the reduction in greenhouse-gas emissions over the complete energy life cycle.
By establishing common requirements for design, safety, integration and performance evaluation, the EN IEC 63341 series provides manufacturers, railway undertakings and infrastructure stakeholders with a common technical foundation. In doing so, these standards can help turn hydrogen-powered rail from an innovative technology into a safer, more interoperable and increasingly practical option for cleaner railway mobility.
Thierry LEGRAND
tlegrand@cencenelec.eu
