Development and optimisation of a dedicated Fuel Cells for Aviation: disruptive next-gen high temperature Fuel Cells technology for future aviation

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 (hydrogen storage and distribution from the tank to the fuel cell system are not considered here):

• Aviation needs are 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). This target is clearly defined in the Clean Aviation SRIA[[https://www.clean-aviation.eu/sites/default/files/2022-01/CAJU-GB-2021-12-16-SRIA_en.pdf]]. Such power level requires capability to dissipate almost the same power of heat, in a dedicated thermal management system;
• Current fuel cell technologies developed by automotive industry operate lower than 100°C at constant operation, which means that fuel cell thermal management system will have to evacuate a large amount of power with a low-grade heat due to FC low temperature;
• Thermal management and especially heat dissipation using a low-grade heat have a massive impact on aircraft performance: aircraft drag increase implies to boost aircraft propulsive system sizing (leading to manage more heat) and requires more energy for the same mission (leading to take on more fuel, and therefore to boost aircraft propulsive system);
• Fuel cell operating temperature increase (120°C +) would significantly help to reduce thermal management effect on aircraft flight performances, and unlock fuel cells applications for high power generation systems;
• Current developed High Temperature PEM-FC technologies (Phosphoric acid doped PBI-based MEAs for instance) are not at the expected level of performance for aeronautic target.

Proposals should target a disruptive 120°C+ constant operating temperature fuel cell technology with the same performances as current state-of-the-art low Temperature PEM technologies.

The integration of such a new fuel cell technology into an aircraft fuel cell system needs to be considered and anticipated but is not the scope of this topic.

Proposals should address the following aspects:

Requirements & specification

• Early in the project, define a projected fuel cell stack using this disruptive fuel cell technology compatible with aircraft environment and constraints (safety, durability, availability, temperature, pressure);
• Define disruptive MEA of this technology specification. Disruptive MEA requirement and a high-level MEA architecture should be defined and agreed early in the project;
• Derive necessary technological bricks to be matured up to TRL 4.

MEA architecture, global consistency and performance

• Define a global MEA architecture by considering the interactions between all the components, layers and interfaces of a MEA: previous development of a disruptive MEA for automotive applications highlighted the need to take into account the global architecture of this component. High performance materials assembly do not meet the expected characteristics (performance, durability) of each component of a MEA taken individually. The overall architecture definition is the key for the development of an efficient MEA;
• Increase the kinetics of the Oxygen Reduction Reaction (ORR), main limiting reaction for PEM MEA;
• Design and develop an efficient electrolyte-catalyst interface to optimise the electrochemical active area;
• Design and optimise the Gas Diffusion Layer (GDL), Micro Porous Layer (MPL) and electrode interfaces to facilitate reactants and products management and ensure good electrical properties;
• Eco-design of the MEA has to be taken into account.

Proton or anion electrolyte technology

• Design a fuel cell technology working at 120°C+ (constant operation);
• Design an electrolyte technology with high proton or anion conductivity and no electrical conductivity;
• Define an electrolyte technology with low gas permeability;

Electrodes

• Design electrodes working at 120°C+ (constant operation);
• Design and optimise a cathode to improve ORR kinetics;
• Define and optimise the catalyst loading for Hydrogen Oxidation Reaction (HOR);
• Optimise catalysts support to improve electrochemical active area on both electrodes.

Gas diffusion layer

• Design GDL working at 120°C+ (constant operation);
• Design and optimise GDL composition and structure to efficiently transport and evacuate reactants from the bipolar plate channels to the electrodes, especially on cathode side where the oxygen transport to the catalysts has a major impact on performances at high current densities;
• Optimise electrical conductivity of GDL;
• Design and optimise GDL with an efficient water management at 120°C+.

In addition, great care should be taken to strength, durability of the MEA, and transient start-up / shut down mode. In particular proposals should address the following:

MEA strength

• Design a MEA able to work with different pressures between anode and cathode;
• Design a MEA with high mechanical resistance.

MEA Durability

• Design a MEA with a durability > 20,000 h.

Start and stop operations

• Design a MEA able to undergo start and stop operations with limited degradation rate;
• Define a MEA able to start at cold temperature.

Proposals may include activity for the test bed development for FC testing, and the development of relevant test protocols for performance, lifetime assessment and operating environment profiles.

Activities developing test protocols and procedures for the performance and durability assessment of electrolysers and fuel cell components proposals should foresee a collaboration mechanism with JRC (see section 2.2.4.3 ""Collaboration with JRC""), in order to support EU-wide harmonisation. Test activities should adopt the already published EU harmonised testing protocols[[]] to benchmark performance and quantify progress at programme level.

Activities are expected to start at TRL 2 and achieve TRL 4 by the end of the project.

The conditions related to this topic are provided in the chapter 2.2.3.2 of the Clean Hydrogen JU 2022 Annual Work Plan and in the General Annexes to the Horizon Europe Work Programme 2021–2022 which apply mutatis mutandis.