Optimum pulse electrolysis for efficiency enhancement of hydrogen production by alkaline water electrolyzers

Alkaline water electrolysis is considered as the most feasible way to realize large-scale hydrogen production from renewable energy sources. However, the poor efficiency performance in low load limits the wide-range operation of alkaline water electrolyzers. The energy loss caused by the parasitic current is the main reason of the poor efficiency in low load. Based on the electrolyzer internal structure, an improved model of alkaline water electrolyzers is proposed and the inefficiency mechanism is illustrated. It is found that by applying pulse current for electrolysis, the efficiency of hydrogen production in low load can be enhanced greatly. The influence of the pulse current magnitude and duty ratio on the efficiency improvement is studied. Under different operation conditions, they can be regulated to achieve the maximum efficiency of hydrogen production. The electrolyzer parameters also affect the efficiency trend, especially the double layer capacitance. Finally, the results are experimentally verified on a 10 kW alkaline water electrolyzer.