Experimental studies on dynamic performance of 250-kW alkaline electrolytic system

Abstract

Alkaline water electrolysis is a mature hydrogen production technology and an important means for future large-scale green hydrogen production and electrical energy storage, while enhancing and optimizing its dynamic characteristic speed is the urgent problem to achieve this goal. In this study, the dynamic response characteristics of the system current, voltage, temperature, hydrogen to oxygen (HTO) and pressure parameters are experimentally investigated at two levels (start-stop and variable load processes) and three-time scales (hours, minutes and seconds) based on the 250-kW industrial alkaline water electrolysis system. The experimental study of cold start (25 °C)→full load (90 °C)→hot shutdown (75 °C)→hot start (70 °C)→full load (90 °C)→cold shutdown (30 °C) revealed that the response time of start-stop process is hourly and temperature is the main limiting factor. The response time of HTO is on the order of minutes based on the variable load test: full load (3500 A, 1.7 MPa)→minimum load (1400 A, 1.7 MPa)→full load (3500 A, 1.7 MPa)→minimum load (800 A, 0.6 MPa). The response of HTO to parameter changes has severe time delay and inertia links, and the latter with significantly longer response time. The response time for different current step is in the order of seconds. This experimental study points out the dynamic performance level of industrial-scale alkaline water electrolysis system at the present stage and provides directions for the optimization of dynamic performance indexes, which is an important guideline for designing control strategies that integrate with renewable energy sources.