On the hazards of proton exchange membrane (PEM) water electrolysis systems using system theoretic process analysis (STPA)

Abstract

Green hydrogen energy is environmentally sustainable and critical to achieving a carbon-neutral society. Among several water electrolysis technologies, the proton exchange membrane water electrolysis (PEMWE) system, when integrated with renewable energy sources (RES), is seen as a promising green hydrogen production method. PEMWE is especially preferred for high-pressure operation, which decreases the energy usage and cost associated with hydrogen compression. However, it also poses significant operational risks, such as component reliability under dynamic operation, potential hydrogen leakage due to overpressure or component failure, possible hydrogen-oxygen mixtures in the system, and other unanticipated operational challenges. To fully understand the PEMWE system’s operational risk and facilitate risk management, this study conducts a systematic risk analysis using the System Theoretic Process Analysis (STPA) method, involving component failure, system design, human and organizational factors. Combined with the automated and dynamic nature of the system, salient issues during the dynamic operation of the PEMWE system, such as control reliability, component communication reliability and thermal runaway risk, are identified semi-quantitatively. This research is expected to provide a case for STPA research in the highly automated and socio-technical process industry. The findings are expected to offer valuable insights into the safety and reliability of the PEMWE system, providing engineers with technical guidelines for safer system designs, operations, and risk engineering applications, while delivering systematic strategies for risk management. Consequently, a more reliable PEMWE system could lead to the efficient utilization of fluctuating RES.