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

The increase in the number of hydrogen (H-2) fuel cell vehicles necessitates the swift installation of requisite infrastructure such as H-2 refueling stations (HRSs). However, the use and storage of high-pressure gaseous H-2 in conventional HRSs limits inventory and poses safety risks. In this regard, ammonia (NH3) is a potential solution as an H-2 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 H-2 carrier. The operation of ammonia-derived H-2 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.

Automated summary

With the increasing number of hydrogen fuel cell vehicles, the installation of necessary infrastructure such as hydrogen refueling stations (HRSs) is crucial. However, the use and storage of high-pressure gaseous hydrogen in conventional HRSs have limitations and safety risks. Ammonia, with its high storage capacity and ability to be stored as a liquid, is considered a potential solution as a carrier for hydrogen. However, ammonia is toxic and can be fatal if accidentally exposed to humans. Therefore, this study aims to develop a process and safety design for HRSs using ammonia as the hydrogen carrier.