Sensing advancement towards safety assessment of hydrogen fuel cell vehicles

The hazardous effects of pollutants emitted by conventional fuel vehicles have moved academic and industrial authorities toward the utilization of a more efficient alternative energy source. Due to its unique characteristics, considerable attention has been recently devoted to hydrogen as an ideal synthetic energy carrier. Despite promising advantages, it is crucial to adopt safety considerations related to health, leakage, fire, and explosion due to mechanical failures and human errors by hydrogen fuel cell users. In the present study, a comprehensive review of safety issues with hydrogen fuel cell vehicles is presented according to hydrogen characteristics and behavior, hydrogen monitoring requirements including international collaborations and formal agreements, regulations, codes, and standards. Also, hydrogen sensor types applicable to fuel cell vehicles, including catalytic hydrogen, electrochemical, semi-conductive metal-oxide, thermal conductivity, optical, palladium (alloy) film-based, and combined technology-based sensors, as well as their detection performances, are discussed. Finally, future directions are proposed regarding sensing and monitoring methods and challenges ahead in the utilization of hydrogen fuel cells in vehicles as an alternative to conventional counterparts.