Faraday Efficiency Study of Pressurized Alkaline Water Electrolyzer

Abstract

According to a BloombergNEF report, China is the largest green hydrogen market, accounting for about 60% of the expected global electrolysis volume in 2022-2023. More than 90% of these electrolyzers are pressurized alkaline water electrolyzers (AWE), like the classic design of Lurgi. AWE manufacturers and end-users place great emphasis on advanced electrodes and membranes to improve power efficiency, and often using 100% Faraday efficiency to calculate current density-based yields.As an end-user, the authors investigated a combination of real AWE operating data and electrochemical engineering principles and discovered that Faraday efficiencies were around 85-93%. Therefore, Aspen ACM simulation models were developed based on detailed internal structures and configurations that well corresponded with plant data, suggesting that many AWE manufacturers exaggerate Faradic efficiencies by to 10%.Some low-cost design improvements are proposed for the bipolar plate and manifold alkali channels, which can improve the Faradaic efficiency by 5-7%, producing higher power efficiency especially when connected to a renewable power source at low loads.