Solid ammonia as energy carrier: Current status and future prospects

Ammonia is very attractive as an energy carrier for its high energy density and potential of being a ‘zero-carbon' fuel. However, ammonia is toxic, and because of the very high vapor pressure of liquid ammonia (∼8 bar at room temperature), there are safety concerns about storing liquid ammonia for end-user applications. Amminex has developed a method to store ammonia safely as solid metal ammines. The Amminex product, Hydrammine™, is a non-pressurized storage material, and has an energy density similar to that of liquid ammonia (∼110 kg H2/m3). It enables safe use of ammonia as an energy carrier for end-user applications. Amminex has been active in integrating the solid ammonia storage technology with PEMFC and SOFC stacks. This article focuses on the potential of ‘solid' ammonia as a carbon-free energy carrier for mobile and transport applications, system integration (PEMFC and SOFC), and future opportunities.