Low mass, compact Regenerative Fuel Cell System (RFCS)


The RFCS technology is developed for use on large telecom satellites as a low mass alternative to batteries. The technology can be utilized in a wide range of energy storage systems where mass is a critical factor, and especially where discharge times are larger than 1 hour.


The Regenerative Fuel Cell System (RFCS) uses hydrogen and oxygen to generate power in an electrochemical reaction within a fuel cell, producing electricity and water. The water is converted back to hydrogen and electricity in an electrolyser. The hydrogen can be stored in a pressure tank or in metal hydride with integrated heat storage. The fuel cell, electrolyser and the gas storage system are the main components and the heaviest parts in a RFCS system. The development activities have focused on mass reduction of these components as well as safety and operational aspects. The technology has been tested in a closed loop system, and operated autonomously for 1350 cycles, equivalent to a 15-year lifetime of a GEO satellite. The technology can be adapted to different sizes, from a few hundred watts to hundreds of kilowatts.

Innovations and advantages of the offer

TDO0157 - High Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack used in testing the closed-loop RFCS breadboard demonstratorThe technology offers high specific energy and power density:

  • Fuel cell power > 1kW/kg
  • Electrolyser power >1kW/kg
  • Electrolyser output pressure: 100 bar
  • Energy density 250 – 600 Whr/kg (depending on discharge/charge time)
  • Integrated heat storage

Further Information

Download a paper with further information on the development of this technology for space


Typical applications could be:

  • Autonomous measurement platforms
  • Autonomous communication stations
  • Aircraft systems
  • Back-up systems for remote areas
  • Distributed renewable energy systems
  • Drones and remotely operated aircrafts (Fuel Cell and Storage only)

Description of Space Heritage

The technology was originally developed for energy storage for large telecom satellites. Next-generation telecom satellites will demand increasing amounts of power up to 30 kW or more. Battery technology able to sustain 30kW over an eclipse length of 72 minutes would have a major impact on the total mass of the satellite. Thus alternative technologies such as the RFCS are attractive, and ESA has funded a series of projects related to the development of a RFCS for telecoms satellites.

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