Hydrogen-Based Materials for Energy Storage and Conversion: The Chemistry Behind the Hydrogen Economy's Next Decade

An international team of more than thirty researchers, spanning Europe, North America, and Asia, has published a wide ranging review in Nature Reviews Clean Technology on the materials science behind hydrogen storage, compression, and conversion. Darren Broom is first author, and Michael Hirscher of the Max Planck Institute for Solid State Research is listed as corresponding author; the team consolidates decades of research on porous adsorbents, metal hydrides, liquid carriers, and hydride based batteries into one assessment of where hydrogen materials science stands today (Broom et al., 2026). For a fuel praised for having the highest gravimetric energy density of any energy carrier, holding onto hydrogen gas has quietly decided whether the hydrogen economy advances or stalls.

What the Review Covers

The authors organize hydrogen based materials into several families. Nanoporous materials, including metal organic frameworks, carbon nanostructures, and zeolites, capture hydrogen on internal surfaces at cryogenic temperatures through physisorption, offering fast, reversible cycling with minimal energy penalty. Metal and complex hydrides absorb hydrogen into a crystal lattice, achieving higher density at near ambient pressure and temperature, though often at the cost of slower kinetics or higher temperatures. Liquid organic carriers and ammonia round out the picture as chemical vehicles for moving hydrogen across oceans using infrastructure similar to existing oil tankers. The review also highlights metal hydride compressors, which use the same absorption and desorption cycle to push hydrogen to the 700 to 875 bar pressures required by type IV tanks in fuel cell vehicles, without the moving parts of a mechanical compressor (Lototskyy et al., 2024).

The 'So What' for the Hydrogen Economy

None of this matters in the abstract. It matters because storage remains the biggest bottleneck between a hydrogen molecule made at an electrolyzer and one delivered to a truck, a furnace, or a power plant. Solid state metal hydrides suited to mobile use can pack hydrogen at densities up to roughly 90 kilograms per cubic meter, more than double the roughly 39 kilograms per cubic meter of usable hydrogen inside a 700 bar tank, per the Department of Energy's own reference design (Scarpati et al., 2024; U.S. Department of Energy, 2025). That advantage can shrink storage enough to fit a hub on a site that would otherwise need acreage a project cannot secure, though the heavy metal content behind it works against hydrides in weight sensitive uses like cars. Hydride based batteries, including nickel metal hydride electrodes and solid state magnesium and calcium electrolytes, point to a second so what: the same chemistry keeping hydrogen contained could also stabilize battery systems competing with hydrogen for grid storage, blurring the line between two technologies often treated as rivals.

Beyond Storage: Batteries and Heat

Hydrides are not confined to gas tanks. The review details how complex hydrides function as solid electrolytes in experimental batteries, offering a path around the flammability concerns dogging lithium ion chemistry, and how hydride pairs are explored as thermal storage media. Compared with current technologies, metal hydrides offer higher heat capacity and can shrink the footprint needed to capture heat from concentrated solar plants or waste streams. Because the same reaction underlies both functions, researchers studying hydride based thermal storage argue a single material class could eventually serve electricity, hydrogen, and heat roles within one facility, though this remains a research direction rather than a deployed reality (Adams et al., 2022).

Market Reality and Remaining Hurdles

Nickel metal hydride batteries remain in widespread commercial use, and metal hydride storage is now moving into material handling equipment: Dumarey Group, working with client H2PumHa, is developing a forklift unit pairing a fuel cell stack with metal hydride storage because it avoids the safety burden of high pressure tanks inside warehouses and cold chain sites (Dumarey Group, 2026). Passenger cars remain harder. The Department of Energy's most recent record puts the cost of a 700 bar compressed tank system at 12.70 dollars per kilowatt hour, above the 2025 target of 9 dollars and the ultimate target of 8 dollars, and hydrides have not displaced compressed gas in light duty vehicles because their volumetric edge comes bundled with weight tanks avoid (U.S. Department of Energy, 2025). Geological storage is advancing separately: the International Energy Agency's (2025) Global Hydrogen Review reports storage in salt caverns with fast cycling and in depleted gas fields was demonstrated through pilot projects this year, including Germany's H2CAST Etzel cavern and Austria's Underground Sun Storage 2030 program, suggesting geological and engineered hydride storage will serve complementary niches.

What the review makes clear is that hydrogen materials science has matured past laboratory curiosity, though no single material yet satisfies every demand of cost, density, kinetics, and safety at once. Two of the review's authors have separately documented a persistent reproducibility problem, where measured storage capacities for the same material vary widely between research groups, a gap that slows translation of results into bankable specifications (Broom & Hirscher, 2016, 2021). Closing that gap, more than any single breakthrough, may decide how quickly these materials move from journals into refueling stations, grid batteries, and heat recovery systems. The next decade will be shaped less by electrolyzer headlines than by whether researchers close the gaps in this toolkit.

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References

Adams, M., et al. (2022). Hydride-based thermal energy storage. *Progress in Energy*, *4*, 032008. https://doi.org/10.1088/2516-1083/ac72ea

Broom, D. P., et al. (2026). Hydrogen-based materials for energy storage and conversion. *Nature Reviews Clean Technology*. https://doi.org/10.1038/s44359-026-00184-z

Broom, D. P., & Hirscher, M. (2016). Irreproducibility in hydrogen storage material research. *Energy & Environmental Science*, *9*, 3368 to 3380. https://doi.org/10.1039/C6EE01435F

Broom, D. P., & Hirscher, M. (2021). Improving reproducibility in hydrogen storage material research. *ChemPhysChem*, *22*, 2141 to 2157. https://doi.org/10.1002/cphc.202100508

Dumarey Group. (2026). *Hydrogen forklift with metal hydrides storage: Fuel cell propulsion integration* [Case study]. https://www.dumarey.com/case-study/hydrogen-forklift-with-metal-hydrides-storage/

International Energy Agency. (2025). *Global hydrogen review 2025*. IEA Publications. https://www.iea.org/reports/global-hydrogen-review-2025

Lototskyy, M. V., et al. (2024). Development of a high-pressure 700 bar metal hydride hydrogen compressor. *Journal of Energy Storage*, *98*, 113072. https://doi.org/10.1016/j.est.2024.113072

Scarpati, G., Frasci, E., Di Ilio, G., & Jannelli, E. (2024). A comprehensive review on metal hydrides-based hydrogen storage systems for mobile applications. *Journal of Energy Storage*, *102*, 113934. https://doi.org/10.1016/j.est.2024.113934

U.S. Department of Energy. (2025). *Onboard type IV compressed hydrogen storage system: Cost and performance status* (DOE Hydrogen Program Record No. 24006). Hydrogen and Fuel Cell Technologies Office. https://www.hydrogen.energy.gov/library/program-records