Exergoeconomic Model of a PEM Fuel Cell

This paper presents an exergoeconomic model of a proton-exchange membrane (PEM) fuel cell stack. The model was calibrated using data from experiments performed in a 1.2 kW PEM fuel cell with varying load, operated at steady state. The exergy analysis was performed with fuel cell operation in the air stoichiometry range between 2 to 4. The results showed the system exergy efficiency varied from 26% to 39%, while the energy efficiency ranged between 37% and 56%. This range is slightly above the fuel cell data sheet from the
manufacturer, which declares a rated energy efficiency of 48%. High pressure, temperature and cell voltage give better exergy efficiency. Variation of system temperature showed no significant impact on the exergy cost, as the PEM fuel cell operates at relatively low temperature in its load range not exceeding 174qC. The exergy cost of the system can be improved by adopting any combination of higher operating pressure, inlet air stoichiometry or cell voltage, which demonstrates a significant improvement in the exergy cost. By reducing
the hydrogen cost from 6.7 $/kg to 1.9 $/kg, a 15 $/GJ decrease in exergy cost can be achieved.