Comprehensive system level modeling of anion exchange membrane water electrolysis for high efficiency hydrogen production

Anion exchange membrane water electrolysis (AEMWE) is recognized as a promising route to low cost, high efficiency green hydrogen production. A comprehensive system model was developed and implemented in Aspen Plus®, in which a zero dimensional electrochemical stack was embedded via a Fortran subroutine, along with an iterative solution scheme implemented within the subroutine. The framework reveals the coupled interaction between mass balance and operating conditions governing water management, and quantitatively resolves phenomena that were previously treated conceptually through a numerical method, enabling direct quantification of water transport and predictive analysis of system behavior. The full Balance of Plant (BOP) (separator, heater, heat exchanger, pumps, chiller, condenser, and dryer) was represented, and simulations were performed across various operating conditions (current density, temperature, pressure). The results are analyzed in terms of the cell voltage, hydrogen purity, water transport, and BOP power consumption. Key findings include: (1) the cathode outlet water flow was reduced by 54.62% as current density increased from 0.4 to 1.8 A/cm 2 , underscoring the necessity of cathode water management; (2) hydrogen purity at the condenser varied widely with operating conditions, reaching 99.84% at 0.4 A/cm 2 , 40 °C and 50 bar; and (3) for high hydrogen production with a moderate energy penalty, operating at 80 °C and 25 bar under high current density was identified as preferable. The developed modeling framework is provided as a reliable tool for AEMWE system design and optimization, enabling systematic evaluation of tradeoffs among efficiency, purity, and production rate.