NOVELTY - A system (s1) comprises solid media and gaseous atmosphere. The solid media having a first condition which is hydrogenated and a second condition which is partially or fully dehydrogenated relative to the first condition, and where the gaseous atmosphere comprises nitrogen.    USE - For mitigating, preventing, or at least counteracting, the production of ammonia.    ADVANTAGE - In the system, the addition of nitrogen to the atmosphere in contact with the hydrogen storage material suppresses ammonia production and contributes to causing the equilibrium of reaction to be driven in the desirable direction; that is, not favoring ammonia formation.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a hydrogen storage system (s2) comprising either a metal-nitrogen compound having a hydrogenated state and dehydrogenated state, and nitrogen (N2) in contact with the metal-nitrogen compound; or a container housing a solid state metal-nitrogen hydrogen storage composition and a gaseous atmosphere comprising nitrogen;    (2) method of cycling hydrogen involving storing hydrogen by reacting hydrogen gas with a hydrogen absorption media in the presence of nitrogen gas, and releasing hydrogen from hydrogenated media in the presence of nitrogen gas;    (3) method (m1) of cycling hydrogen in a solid state metal-nitrogen composition having a hydrogenated state and a dehydrogenated state involving liberating hydrogen from a hydrogenated state of the metal-nitrogen composition by heating the composition in a nitrogen-containing atmosphere at an elevated temperature to evolve hydrogen gas from it, to produce the dehydrogenated state; and generating a hydrogenated state of the metal-nitrogen composition by exposing the dehydrogenated state to an atmosphere comprising hydrogen gas and nitrogen gas;    (4) method of storing hydrogen gas involving reacting hydrogen gas with a hydrogen absorption media in the presence of nitrogen gas to form a hydrogenated media; and    (5) method of releasing hydrogen gas from a hydrogen storage system comprising hydrogenated media, involving adjusting at least one of temperature and pressure of the system while exposing the media to an atmosphere comprising nitrogen gas.