Numerical modeling and performance of an alkaline water electrolysis system

Abstract

Alkaline water electrolysis (AWE) is the most mature and reliable technology for producing green hydrogen among other types of water electrolysis. Although AWE has been developed over recent decades, both the capital and operational costs of AWE are still so high that hydrogen produced from AWE is economically less competitive compared with other hydrogen production technologies such as methane steam reforming. To reduce the operational cost of AWE hydrogen production, the AWE operations need to be optimized. In this study, to capture the effect of operating conditions on the AWE system performance, the AWE system model developed in our previous work has been simulated by varying the operating temperature and pressure. The simulation results present that higher operating temperature increases the system efficiency only in the relatively high current density region. This is because the heater power consumption has increased significantly in the low current density region while the stack efficiency improves at high temperatures. Meanwhile, the increase in operating pressure improves the system efficiency by only up to 10 bar, and then decreases. This is due to a decrease in stack efficiency. The model developed in this study can be used to find the optimal configuration and operating condition of the AWE system.