High temperature proton exchange membrane fuel cells (HT‐PEMFC) have a promising market in micro‐combined heat and power (μ‐CHP) applications. Operating above 150 °C, they would better cope with return temperatures of typical heating systems than conventional PEMFCs and would allow simplification of system regulations dedicated to failure prevention.Single cell and 500 We HT‐PEMFC stack integrating Celtec P 1000 MEAs were fed with synthetic reformate and air and successfully operated at 160 °C under accelerated typical annual μ‐CHP profile. The single cell was unaffected by 500 h of current cycling while stop/start cycles induced some voltage loss. After 658 h of cumulated operation, stack performance loss was limited at 7.6%: its electrical efficiency (LHV) decreased from 30.6 to 28.3%. Moreover, four initial stop/start cycles weakly impacted its performance, indicating that selected shutdown/restart protocol is convenient for field application. Conversely, after additional start/stop cycles, degradation rate was increased by stop/start cycling and some specific cells (mostly associated with lower initial OCV) exhibited significantly higher degradation rates. Finally, voltage transient evolution during current step exhibits undershoot which magnitude is strongly depends on cell location in the stack: it increased at stack dead‐end and for cells exhibiting highest degradation rates.

Single cell and 500 We stack integrating Celtec P1000 MEAs were operated in continuous mode at 0.4 A cm–2 and 160 °C, under simulated reformate and air. Single cell's ohmic resistivity was almost unaffected by 1,100 h of ageing but the cell progressively switched from a cathodic to an anodic mass transfer limited operation. The stack was operated for 658 h, exhibiting the same behaviour and an additional increase in cell voltage distribution heterogeneity. CO2 proved to have negligible effect on performances but performance losses induced by ageing are doubled in the presence of CO. Post‐testing experiments revealed that anode electrochemical active area was dramatically decreased and that platinum content was also decreased. Finally, results showed that a convenient shut‐down procedure could prevent or limit degradations associated with storage.

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