Proposals should target a fuel cell system with a power density > 1.5kW/kg at a power level of at least 1 MW. The technology (Proton Exchange Membrane Fuel Cell) that is emerging from the automotive industry through car manufacturers is of interest for aeronautic industry, but some issues are still to be solved.

• The power of the fuel cell systems coming from the automotive industry is usually limited roughly to 100kW. Aviation needs are more in the range of 1 to 5MW depending on the size of the aircraft and/or the systems to supply with power (propulsive or non-propulsive). Development of 250 kW FC stack and scalability of FC system and components for an at least 1.5 MW module seems thus compulsory in order to allow aircraft application. This target is moreover clearly defined in the Clean Aviation SRIA;
• The stacks available today are not adapted to the environment in which they will have to operate: temperature ISA-35, pressure 0,2 bar (45 kft), vibrations, etc;
• The requested power is not achievable with only one stack. The following should be defined:
  • • The optimal size of the stack;
    • The architecture of multi-stack systems.
• The cost of the technology needs to be reduced. Sizing a unitary stack of a reasonable amount of power will ease its integration in different size of aircraft and for propulsive and non-propulsive systems. This will increase the numbers and ease cost reduction;
• The lifetime of the fuel cells should be increased;
• Safety issues shall be considered right from the start. The means of compliance in order to answer to qualification/certification needs are not available. The certifications rules should be created/adapted.

The integration of the full system into the aircraft needs to be considered and anticipated but is not the key focus and will be dealt with in a separated Work Programme.
Other hydrogen sub systems (storage, distribution) are outside of the scope of this topic. Proposals may include activity for the test bed development for FC testing in simulated A/C applications, and the development of relevant test protocols for performance and lifetime assessment for A/C load and operating environment profiles.