Safe Packaging of Ammonia for Compact Hydrogen Sources

The U.S. Army has funded development of compact hydrogen generators that extract hydrogen from anhydrous ammonia. However, use of these ammonia-based hydrogen generators will likely be restricted unless the ammonia can be stored such that the potentialfor a dangerous ammonia release is minimal.During Phase I, we demonstrated safe, high-density storage of anhydrous ammonia in monolithic, closed-cell foam materials.We propose development of an ammonia-storage tank filled with an appropriate ammonia-storage material. Based on Phase I testing, we predict our storage tank will have an ammonia capacity of 500g (1.5 kWhe), an overall volume of 1.1 to 2.0 liters, and atotal mass of 750 to 1100g (including 500g ammonia). The maximum ammonia release rate will be low enough to minimize safety concerns yet high enough to supply the ammonia-based hydrogen generators.Development of a compact, lightweight, and safe means for storing anhydrous ammonia will eliminate the principal drawback of ammonia-based hydrogen sources for fuel-cell-based power supplies. Once an appropriate ammonia-storage system is available, theexisting ammonia-based hydrogen generators can rapidly move toward deployment in the U.S. Military for compact power supplies. Many commercial, compact-power applications will also become feasible once safe ammonia storage is available. In addition,these ammonia-storage systems may find application for safe storage of other toxic and flammable chemicals, such as propane.