Design‐based risk assessment on an ammonia‐derived urban hydrogen refueling station

Summary The increase in the number of hydrogen (H2) fuel cell vehicles necessitates the swift installation of requisite infrastructure such as H2 refueling stations (HRSs). However, the use and storage of high‐pressure gaseous H2 in conventional HRSs limits inventory and poses safety risks. In this regard, ammonia (NH3) is a potential solution as an H2 carrier with high storage capacity that can be stored as a liquid. However, NH3 is toxic and accidental exposure to it is fatal for humans. Therefore, this study aims to develop a process and safety design for HRSs using NH3 as the H2 carrier. The operation of ammonia‐derived H2 refueling stations comprises dehydrogenation and refueling processes, for which quantitative risk assessment was performed based on process design data. Consequently, it was determined that NH3 leakage from the storage tank was the dominant accident scenario and that the associated risk exceeded the acceptable risk criteria. Therefore, we proposed a risk mitigation strategy that involves installing a dike to guarantee safe design and operation.