Chapter 10: Hydrogen production from ammonia cracking

his chapter discusses the basic concepts of hydrogen production from ammonia. Ammonia, which is a global commodity chemical, has an extraordinarily high storage capacity for hydrogen, that is, 17.65% by weight, and a hydrogen density of 115–120 kg hydrogen/m3 liquid ammonia. While ammonia production through the Haber process can be made green with the replacement of natural gas by water as a hydrogen source, it is at the point of usage of hydrogen, where the decomposition of ammonia, limited by higher temperatures, and subsequent purification of the hydrogen, with its associated capital costs, are the primary roadblocks to commercialization. These two steps lower the “round-trip” efficiency of hydrogen storage and transport and will need significant efforts to make it commercially viable.

The authors review the diverse methodologies for hydrogen storage, critical for the scalability of hydrogen-based renewable energy systems, including high-pressure gaseous storage, cryogenic liquid hydrogen storage, cutting-edge solid-state hydride storage, and innovative liquid organic hydrogen carriers and ammonia. The second part of this chapter deals with the complexities of ammonia cracking/decomposition and the extensive R&D in the area of heterogeneous catalysis. The aim is to provide a realistic appraisal of the challenges