From Material Capacity to System Viability: A Critical Systems‐Level Review of Hydrogen Storage Technologies

The transition to a hydrogen economy relies on safe, efficient, and scalable hydrogen storage systems. However, many studies continue to evaluate material performance based on theoretical capacity without accounting for system‐level constraints. This paper provides a critical review of physical and chemical hydrogen storage technologies, including compressed gaseous hydrogen (CGH ₂ ), liquid hydrogen (LH ₂ ), physisorption, intermetallic hydrides, Mg‐based hydrides, complex hydrides, chemical hydrides, and metal–water hydrogen generation systems. The primary focus is on the gap between material‐level capacity and deliverable system capacity, as well as thermal requirements, energy consumption, cycle efficiency, CAPEX, technology maturity, and application‐specific needs. Furthermore, the review presents a scenario‐based framework for safety analysis, examining pressure, temperature, hydrogen inventory, release kinetics, geometry, ventilation, and material compatibility simultaneously. It critically distinguishes the roles of the Joule–Thomson effect, transient blowdown, flash vaporization, and flammable cloud formation, as well as the differences between jet fires, flash fires, deflagrations, and detonations. Additionally, the review synthesizes published insights from real‐gas thermodynamics, CFD and LES dispersion models, multiphysics simulations, and event tree analysis (ETA) to critically evaluate predictive frameworks for leakage, dispersion, and ignition consequences. Ultimately, the article demonstrates that no single technology is inherently safe or superior; technology selection must be based on an integrated assessment of performance, safety, infrastructure, cost, and life cycle. Future development pathways must shift from mere material optimization toward safe‐by‐design, system‐integrated hydrogen storage.