Ammonia Storage as Complex Compounds for a Safe and Compact Hydrogen Source

Ammonia is an attractive media for storing hydrogen for fuel cells because it exceeds 17% hydrogen by weight and leaves only nitrogen after decomposition and hydrogen removal. Safety questions related to the relatively high vapor pressure of ammonia canbe alleviated if ammonia is stored on an absorbent. Complex compounds are the best absorbents for ammonia, in that they have extremely high storage density, can release the full ammonia charge at constant pressure, and are available with different degreesof vapor pressure suppression. Rocky Research has been developing thermal equipment utilizing ammonia absorption on complex compounds since 1985, and we have solved historical problems of salt migration while increasing reaction rates dramatically.Proposed in Phase I are measurement of vapor pressure and ammonia uptake of compounds which were not previously characterized since they were not suitable for refrigeration cycles. Following experimental characterization of new compounds, selection ofoptimal compound(s) will be made from our entire database. A demonstration storage system will be built with one of the selected compound(s), and tested in Phase I. Based on the demonstration system in Phase I, ammonia storage vessels will be fullyoptimized for minimum weight in Phase II. Potential commercial applications for an ammonia storage & fuel cell system are extremely numerous and include remote power sources for campers and rescue workers, and power packs for computers and otherelectronics. They would be used for any application where regenerable electric power storage for more than a few watt-hours is required. Replaceable ammonia storage vessels could give the power source unlimited life. The proposed R&D will result in thelightest reduced-pressure ammonia storage vessels possible. Development of ultra light weight ammonia storage vessels will contribute to successful development of small-scale complex compound refrigeration systems as well as the target fuel cellapplication.