Metal steam reforming in storing and transporting hydrogen: A review and perspectives on the utilization of fluidized bed technology

Metal steam reforming is a promising approach for on-demand hydrogen production. The concept relies on reversible oxidation-reduction cycles, where metals react with steam to release hydrogen and heat, and metal oxides are regenerated using renewable energy, enabling energy storage and transportation. This review analyses metal steam reforming including thermochemical principles, material selection, and integration pathways, with emphasis on fluidized bed technology. Conducted analysis indicates that metals could offer high volumetric energy density, safe, non-cryogenic transport, and potential compatibility with existing boiler infrastructure. However, practical deployment must address challenges such as sintering, particle handling, and limited roundtrip efficiency. Iron-based cycles appear attractive due to abundance, cost, and mature reduction pathways. Retrofitting fluidized bed units could accelerate demonstration at scale, but more experimental evidence is still needed. To determine system-level viability, future work should prioritize techno-economic and life-cycle assessments and comparative benchmarking against other transport and storage routes under realistic operating scenarios.