Safety of ammonia as a hydrogen energy carrier.

The safety of ammonia was divided into a fire hazard (flammability) and a health hazard. The flammability of ammonia decreased compared to other hydrogen energy carriers and carbon-based fuels because of the high flash point. The health hazard (frostbite and toxicity) of ammonia was large (3) and same as those of liquid hydrogen, LNG and carbon monoxide. Tolerance concentration in ACGIH was used as a ranking of toxicity. The tolerance concentration increased with decreasing the vapor concentration and the fuel content in water. The insoluble ammonia-absorbed zirconium phosphate has a large ammonia storage capacity of 10 wt%, a small vapor concentration in the presence of water and a small ammonia content in water below 1 ppm. It will be a candidate to reduce the toxicity of the leaked ammonia in a closed space. • The fire hazard of ammonia was small because of the high flash point. • The health hazard of ammonia was large (3) and same as those of liquid H 2 and LNG. • Ammonia presents a health hazard above a certain concentration in the air. • Techniques for the safe removal of escaped ammonia are needed. • Zirconium phosphate will be used to reduce the toxicity of the leaked ammonia. [ABSTRACT FROM AUTHOR]