PEM Electrolysis Failure Scenarios Identified By Failure Modes and Effects Analysis (FMEA)

PEM electrolysis is the most promising technology for clean hydrogen production. Quantitative risk assessment (QRA) is used to support safe and reliable deployment and operation of electrolyzers. A bottom-up failure modes and effects analysis (FMEA) was performed on a lab-scale PEM electrolyzer under normal operating conditions. We identified three significant hazards (hydrogen release, oxygen release, and hydrogen-oxygen mixing), and accompanying relevant scenarios, that apply to electrolyzers. There were 20 failure scenarios found that could lead to a hydrogen release, 45 for an oxygen release, and 68 for hydrogen and oxygen mixing. The ignition of either a hydrogen release or a collection of hydrogen and oxygen gas could cause a jet fire or explosion that poses risk to both facility personnel and surrounding equipment. The release of oxygen can also pose health risks to surrounding personnel and cause damage to nearby equipment over time. These scenarios are classified in terms of the component of interest, its failure mode, the sequence of events following failure, and the end consequence. The gas-water separators, pump responsible for supplying water to the electrolyzer stack, and the stack itself were found to contribute to the largest number of high-risk scenarios. This paper describes all of the scenarios. It supports the identification and mitigation of safety and reliability issues seen in current hydrogen electrolyzer technology as well as set the foundation for a complete QRA on hydrogen electrolyzers. Consequently, these findings will allow risk-informed decision-making for the design, operation, and deployment of PEM electrolyzers.