Concept development and testing of the UK’s first hydrogen-hybrid train (HydroFLEX)

Charles Calvert*, Jeff Allan, Peter Amor, Stuart Hillmansen, Clive Roberts, Paul Weston

*Corresponding author for this work

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In October 2018, Porterbrook and the University of Birmingham announced the HydroFLEX project, to demonstrate a hydrogen-hybrid modified train at Rail Live 2019. The concept of modifying a Class 319 Electric Multiple Unit was developed, with equipment including a fuel cell stack, traction battery, 24 V control system and hydrogen storage elements to be mounted inside one of the carriages. This was followed by procurement of a fuel cell stack, traction batteries, and control equipment, which was then installed inside the train, being fixed to the seat rails. One substantial change from the concept was the provision of considerably more hydrogen storage than the minimum necessary, providing the train with more potential to be further modified to allow for higher speed mainline testing. After the Rail Live exhibition where HydroFLEX was demonstrated, numerous modifications were performed to increase the reliability and power of the HydroFLEX train, primarily concerned with modifying the base train logic, with the aim of a successful mainline test. Supporting this effort was a multitude of documentation concerning safety, operations, and approvals to gain approvals from the relevant approvals bodies. The project demonstrated the feasibility of using hydrogen fuel cells as an autonomous fuel for railway propulsion systems, which has the potential for full decarbonisation.

Original languageEnglish
Pages (from-to)248-257
Number of pages10
JournalRailway Engineering Science
Issue number3
Publication statusPublished - 1 Sept 2021


  • Fuel cell
  • Hybrid
  • Hydrogen
  • Systems engineering

ASJC Scopus subject areas

  • Computational Mechanics
  • Transportation
  • Mechanical Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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