A square filter-press alkaline water electrolyzer for wide power range operation via flow enhancement and parasitic current suppression

Abstract

Hydrogen production via direct water electrolysis under conditions of large power fluctuations presents a major challenge in renewable energy storage applications. This study introduces a novel square filter-press alkaline water electrolyzer featuring independent gas outlet manifolds, specifically developed to ensure efficient hydrogen production across a wide range of power fluctuation conditions. Compared with conventional circular electrolyzer designs, the modified configuration demonstrated enhanced gas purity and Faradaic efficiency even at low current densities (as low as 10 mA cm^-2). Additionally, the new design achieved reduced electrolysis voltages, especially at higher current densities. These performance improvements are attributed to optimized manifold structures that enable efficient gas evacuation, thereby minimizing inefficiencies caused by gas bubble entrapment. The study also identifies and analyzes two types of parasitic currents, LPPC and SPPC, to better understand and mitigate their impact on both gas purity and electrolysis efficiency. These innovations significantly expand the operational power range of electrolyzer systems, enhancing their compatibility with renewable energy sources' inherent power fluctuations while improving overall efficiency and operational safety.