Water electrolyzer operation scheduling for green hydrogen production: A review

Green hydrogen, produced through splitting water by water electrolyzers using renewable electricity, emerges as a clean and sustainable energy solution to reduce carbon emissions. However, the inherent intermittency and randomness of renewable energy directly impact the operational states of electrolyzers, notably reducing their operational lifespan and hydrogen production efficiency. Therefore, it is crucial to investigate how to efficiently allocate power and regulate the operational states of electrolyzers to alleviate the negative impacts of power fluctuations, thereby improving operational flexibility and system stability. To fill up the gap, this work systematically discusses state-of-the-art operation scheduling strategies for three primary water electrolyzers: alkaline water electrolyzer, proton exchange membrane water electrolyzer, and solid oxide electrolysis cell. To elaborate, water electrolysis principles, operational characteristics and states, and modeling of these electrolyzers are first detailed, clarifying the background and basis of this work. Subsequently, various optimal scheduling techniques for these electrolyzers are classified and discussed based on their types and renewable-hydrogen production configurations. Moreover, comprehensive Tables employing diverse evaluation indicators are presented to offer readers a clear and intuitive comprehension, highlighting the most critical and relevant aspects, such as renewable and electrolyzer specifications, scheduling schemes, application scenarios, pros and cons, etc. At last, current challenges and future perspectives are elaborated to promote more efficient, reliable, and adaptable scheduling optimization and contribute to advancing relevant renewable hydrogen technologies.