A segmented alkaline water electrolysis system with adaptive power control for enhanced low-power operation and gas purity

Renewable-driven alkaline water electrolysis (AWE) suffers from operational restrictions at low power because declining current density promotes gas crossover across the diaphragm, leading to unsafe hydrogen-to-oxygen (HTO) impurity levels. To resolve this fundamentally, the present study proposes a segmented AWE architecture coupled with an adaptive power control strategy. Multiple electrolytic cells are grouped into independently powered sets, allowing the active electrode area to be dynamically reconfigured: when the operating current would otherwise leave the recommended density range of 2000-4000 A m −2 , cell sets are switched in or out to maintain the current density within safe bounds. This approach physically decouples the total input power from the current density of individual cells, directly suppressing the driving force for impurity accumulation rather than merely mitigating its effects. Under the same variable power profile, the segmented design expands the useable power range from 45 to 100% (conventional) to 2.8–100%, and the cumulative time during which the current density falls outside the recommended window is reduced from 7.34 h to 1.94 h. Crucially, whereas a conventional AWE accumulates HTO exceeding 1.8% for 2.35 h, the proposed strategy keeps HTO below this threshold throughout, enabling continuous and safe hydrogen production without nitrogen purging or shutdown.