Thermochemical Hydrogen Storage via the Reversible Reduction and Oxidation of Metal Oxides

Abstract

In this work, we perform a technical analysis of a cyclic reduction and oxidation process of metal oxides applied as a hydrogen storage route. Hydrogen is used to reduce a metal oxide and form steam, and regenerated by oxidizing the reduced metal oxide with steam. The reduced metal acts as the solid storage medium, which could be transported or used for stationary applications. Suitable metal oxides were screened according to the following performance indicators: specific energy demand (enthalpy change of reaction), thermodynamic conversion extents, specific storage density, resistance to sintering (melting point), and material cost. Iron oxide was then selected as the most promising candidate. A thermodynamic model was developed to determine favorable process temperatures of >400 °C for the hydrogen storage step and 100–500 °C for the hydrogen release step. The energy demand of the storage was calculated to be 27% of the lower heating value of hydrogen. Vis-a-vis other hydrogen storage methods, the iron-based storage exhibits drawbacks for on-board mobile applications but could be attractive for large-scale and long-term storage applications.

Ce-Doped TiZrCrMn Alloys for Enhanced Hydrogen Storage

“…Hydrogen has great potential of becoming an ideal energy carrier in the future because it is abundant and environmentally friendly and has a high calorific value per unit mass. − The development of safe and efficient hydrogen storage technologies is critical for the large-scale application of hydrogen, such as in fuel cell vehicles. Storing hydrogen in a solid-state medium is considered one of the safest and most effective ways to achieve the widespread application of hydrogen in the future. − …”

Materials Research Directions Toward a Green Hydrogen Economy: A Review

“…The best oxides for H 2 storage are found to be Fe 3 O 4 , GeO 2 , MoO 2 , SnO 2 , ZnO, and WO 3 supported on Al 2 O 3 , TiO 2 , Cr 2 O 3 , MnO, and MgO . Ti 4 M 2 O y mixed oxides (Ti 4 Fe 2 O, Ti 4 Ni 2 O) have demonstrated good hydrogen storage properties at room temperature .…”

Materials Research Directions Towards a Green Hydrogen Economy: A Review

“…They participate in a reversible redox cycle with H2 as a reducing agent and H2O as an oxidizing agent, where the oxidation reaction results in a high-purity hydrogen production (Eq 4). 118 MexOy + zH2 <-> MexOy-z + z H2O(g) (4)…”

“…The best H2 storage oxides such as Fe3O4, GeO2, MoO2, SnO2, ZnO, and WO3 are supported with Al2O3, TiO2, Cr2O3, MnO, and MgO. 118 Ti4M2Oy mixed oxides (Ti4Fe2O, Ti4Ni2O) have demonstrated good hydrogen storage properties at room-temperature. 119 Also hybrid ceramics, such as NiCo2O4/TiO2, are an efficient and novel hydrogen storage material.…”