How hydrogen trains can help decarbonise the transport system

HydroFLEX wide

The UK’s first hydrogen train, HydroFLEX, was developed by Porterbrook in partnership with the Birmingham Centre for Railway Research and Education (BCRRE) at the University of Birmingham. It will undergo mainline testing in March 2020.

Executive summary

  • Electrification is the best way to decarbonise the rail network. However, system-wide electrification is unlikely to be completed in time to achieve the Government’s decarbonisation targets.

  • Hydrogen and battery technologies are the most viable alternatives to achieve decarbonisation of the rail network. Hydrogen trains are potentially carbon neutral in operation, while delivering similar performance to existing diesel trains.
  • HydroFLEX is the UK’s first hydrogen train, developed by Porterbrook in partnership with the Birmingham Centre for Railway Research and Education. HydroFLEX will commence mainline testing in March 2020.
How it works

The HydroFLEX system was created by retrofitting an existing Class 319 train with a hydrogen power pack and battery. This gives it the ability to operate along existing electrified routes (on either 750 DC third rail or 25kV overhead power) as well as being able to operate in self-powered mode without the need for diesel engines.

In the HydroFLEX train, up to 20kg of hydrogen is stored in high pressure tanks. This is then passed through a pressure regular and combined with oxygen from the air in the fuel cell, which produces 100kW of electricity. Two Lithium ion battery packs then store the electrical energy, which is then used to power the train using the existing Class 319 traction equipment. There are no harmful emissions; the only by-product is water.

The performance of hydrogen-powered trains is similar to those powered by diesel combustion, but since they are powered through electric motors, they are quieter and benefit from a smoother, quicker ride with greater acceleration providing improved journey times. However, in the short term, hydrogen could not be adapted for high-speed trains, or very long-range trains due to the volume of hydrogen needed.

How the HydroFLEX train works


Download briefing