Project Profile: HydroFLEX Hydrogen Train, United Kingdom

The HydroFLEX project represents the UK’s pioneering entry into hydrogen-powered rolling stock, successfully retrofitting a Class 319 electric multiple unit with a hydrogen fuel cell powertrain. This initiative serves as a critical demonstrator for decarbonizing non-electrified routes on the national rail network. The train’s bi-modal design ensures operational flexibility across existing infrastructure, providing a key pathway towards achieving the UK’s 2040 rail decarbonisation targets.

Technical Specifications

The HydroFLEX demonstrator is engineered on the robust chassis of a Class 319 EMU, chosen for its versatility and existing approvals for mainline operation. The core of the conversion is an integrated hydrogen powerpack, which includes four high-pressure Luxfer cylinders storing 20kg of hydrogen gas. This fuel is fed into a Ballard FCveloCity-HD fuel cell system, which generates approximately 100kW of electrical power through an electrochemical reaction with ambient oxygen. The sole emission from this process is clean water.

Power management is controlled by a sophisticated system that directs electricity from the fuel cell to the traction motors and a Denchi Group lithium-ion battery pack. This battery system captures surplus energy, such as that from regenerative braking, and provides a power boost during high-demand phases like acceleration, ensuring smooth and responsive performance. A key engineering feature is its bi-modal capability, allowing the train to draw power from its hydrogen system on non-electrified lines, as well as from conventional 25kV AC overhead lines or 750V DC third rail, making it one of the most flexible rolling stock assets on the network.

Key Takeaways

• Pathway to Decarbonisation: HydroFLEX provides a proven, low-emission alternative to diesel multiple units (DMUs), directly addressing the UK’s 2040 rail decarbonisation target on routes where full electrification is not economically viable.
• Infrastructure-Agnostic Operation: Its bi-modal capability to operate via hydrogen, overhead lines, or third rail minimises the need for immediate, widespread infrastructure changes and maximises fleet flexibility for train operating companies.
• Collaborative Innovation Model: The project’s success, driven by a partnership between academia (BCRRE), asset owners (Porterbrook), and specialist technology suppliers (Ballard, Denchi), establishes a powerful template for future rail technology development in the UK and beyond.

Frequently Asked Questions (FAQ)

What is the UK’s HydroFLEX train?

The HydroFLEX is the United Kingdom’s first hydrogen-powered train. It is a retrofitted Class 319 electric train that uses a hydrogen fuel cell and an onboard battery system to generate electricity, allowing it to operate on non-electrified railway lines with zero carbon emissions at the point of use.

Who developed the HydroFLEX project?

The HydroFLEX project was a collaborative effort led by the Birmingham Centre for Railway Research and Education (BCRRE) at the University of Birmingham. Key partners included rolling stock company Porterbrook, who provided the train, and technology specialists like Ballard Power Systems for the fuel cell and Denchi Group for the battery pack.