Fuel Cell heat recovery through Metal Hydrides and Phase Change Materials for the optimization of hydrogen supply

This work investigates the thermal integration of metal hydride hydrogen storage with a proton exchange membrane fuel cell for waste heat recovery. Three metal hydride families (AB 5 , AB 2 and AB) are comparatively assessed to identify suitable candidates for fuel cell–coupled operation. Experimental fuel cell tests show that the fraction of recoverable waste heat increases from approximately 60% to more than 80% when a dedicated heat chamber is employed. System-level modelling demonstrates that this recovered thermal power is sufficient to sustain hydrogen desorption from metal hydrides under typical operating conditions. Among investigated materials, AB 5 -type alloys exhibit the most balanced behavior, combining moderate equilibrium pressures, limited hysteresis and adequate kinetics, while AB 2 alloys provide a higher storage capacity at the expense of increased pressure requirements. The introduction of paraffin-based phase change materials with melting temperatures between 21 °C and 27 °C enhances thermal robustness during transient operation by buffering excess heat. • AB 5 alloy offers optimal balance of stability, plateau pressure and reversibility. • Waste heat recovery from proton exchange membrane fuel cells exceeds 80%. • Phase change materials with melting points of 21–27 °C improve thermal buffering. • Fuel cell waste heat sustains hydrogen desorption from metal hydrides. • System-level feasibility of fuel cell and metal hydride thermal coupling.