Techno-Economic Insights into Ammonia as a Hydrogen Vector: Synthesis, Cracking, Storage, and Supply Chain Solutions

Abstract

Amid the global energy crisis, green hydrogen emerges as a potent energy carrier, yet the hydrogen economy grapples with economic viability, low volumetric energy density, storage, and safety issues that hinder its direct utilization. In this context, ammonia serves as an efficacious hydrogen carrier on account of its excellent volumetric and gravimetric hydrogen density, ability to store at low pressure and its ease of catalytic decomposition, enabling onsite H2 production without greenhouse gas emissions. The production of ammonia primarily implied the Haber-Bosch process alongside electrochemical and thermochemical methods, while ammonia decomposition to hydrogen relies on thermal cracking, electro/photo chemical, plasma- assisted decomposition employing suitable catalysts, notably the extensively studied catalyst-assisted thermal cracking of NH3. The present review explores diverse synthetic routes for the synthesis of ammonia and its storage strategies, catalyst-driven decomposition, and challenges associated with the development of proficient catalysts. Furthermore, this review ruminates on strategies used to scale up cutting-edge reactor technology for green NH3 decomposition by the scientific community from the very outset to the contemporary research outcomes, along with highlighting bottlenecks to industrial entry and commercialization with respect to other hydrogen carriers, production and transport costs, and demand and supply constraints.