Researchers at the University of Newcastle have developed an iron-based metal hydride that stores hydrogen safely at moderate temperatures and pressures, potentially solving one of the major obstacles to hydrogen fuel adoption.

The material absorbs hydrogen gas at room temperature under modest pressure, storing it as solid metal hydride. Gentle heating to 80-100°C releases the hydrogen for use. This reversible storage approach is much safer than compressed hydrogen gas stored at 700 bar pressure.

Dr. Andrew Donne, who leads Newcastle’s hydrogen research group, said the key innovation was finding catalyst additives that improve the kinetics of hydrogen absorption and release. “Pure iron hydrides work in principle but are too slow for practical applications. Our additives speed up the reactions by two orders of magnitude.”

Hydrogen is often promoted as a clean fuel because it produces only water when burned or used in fuel cells. But storing and transporting hydrogen efficiently has proven difficult. As a gas, hydrogen has low energy density and must be compressed to extremely high pressures or cooled to cryogenic temperatures to achieve acceptable storage capacity.

Metal hydrides offer an alternative. Some metals and alloys absorb hydrogen, forming solid compounds with hydrogen densities exceeding liquid hydrogen. The challenge has been finding materials that work at practical temperatures and pressures while being cheap enough for commercial use.

Existing metal hydrides typically use expensive elements like titanium, vanadium, or rare earth metals. Iron is abundant and cheap, but iron hydrides normally require high temperatures or pressures that make them impractical.

The Newcastle team’s approach uses nanostructured iron with small amounts of nickel and cobalt as catalysts. The nano-scale structure provides large surface area for hydrogen absorption, while the catalysts reduce the activation energy for hydride formation.

The material can store about 4% hydrogen by weight, lower than some advanced hydrides but sufficient for many applications. For comparison, compressed hydrogen at 700 bar achieves about 5% weight fraction when you include the weight of storage tanks.

But the metal hydride system operates at much lower pressures, around 10-20 bar, which means lighter, cheaper tanks and fewer safety concerns. High-pressure hydrogen tanks are essentially bombs if they rupture, while metal hydride storage is inherently safer.

The research team has demonstrated small-scale prototypes storing about one kilogram of hydrogen, enough to power a fuel cell vehicle for 100 kilometres. They’re now working on scaling up to practical tank sizes storing 5-6 kilograms for 500+ kilometre range.

Heat management is one challenge. Absorbing hydrogen is exothermic, releasing heat that must be removed to maintain absorption rates. Releasing hydrogen is endothermic, requiring heat input. Managing these thermal loads efficiently is critical for practical systems.

The team designed tank configurations with integrated heat exchangers using vehicle coolant to manage temperatures. This adds complexity but appears manageable with existing automotive thermal management technologies.

Another consideration is refueling speed. Compressed hydrogen vehicles can refuel in 3-5 minutes, comparable to gasoline. Metal hydride refueling takes longer, typically 10-20 minutes, because of thermal management requirements. That’s slower but still acceptable for most applications.

The research received $4.2 million in funding from the Australian Renewable Energy Agency (ARENA) and industry partners including BOC, Australia’s largest industrial gas supplier. Those partners are interested in hydrogen storage for industrial applications and potentially fuel cell vehicles.

Australia has significant interest in hydrogen as an export commodity. Green hydrogen produced from renewable energy could potentially be exported to Asia as either ammonia or stored in metal hydrides for easier shipping.

The iron hydride material could be useful for stationary hydrogen storage supporting renewable energy systems. Solar and wind farms could produce hydrogen during periods of excess generation, store it in metal hydrides, then release it later to generate electricity when renewables aren’t producing.

That’s similar to battery storage but potentially cheaper for long-duration storage. Batteries are cost-effective for hours of storage but become expensive for days or weeks of storage, where hydrogen systems might have advantages.

Economic comparisons between batteries and hydrogen storage are contentious because costs are rapidly changing for both technologies. Battery costs have fallen faster than most experts predicted, while hydrogen system costs haven’t declined as quickly as hoped.

Whether iron hydride storage becomes commercially viable depends partly on manufacturing costs at scale. The team estimates their material could be produced for $5-8 per kilogram, giving storage costs around $100-150 per kilogram of hydrogen capacity. That’s competitive with high-pressure tanks but more expensive than simply storing hydrogen as compressed gas in geological formations or salt caverns.

The Newcastle research builds on decades of hydrogen research at Australian universities. CSIRO, UNSW, and several other institutions have hydrogen programs researching production, storage, and utilisation technologies.

The federal government’s National Hydrogen Strategy, released in 2019 and updated in 2023, aims to position Australia as a major hydrogen exporter by 2030. Whether that happens depends on many factors including technology development, production costs, and international demand.

Japan, South Korea, and other Asian nations have hydrogen strategies involving imported hydrogen to decarbonise their economies. Australia, with abundant renewable energy resources, is positioning itself as a potential supplier.

Whether hydrogen becomes a major energy carrier or remains a niche application in industries like steelmaking and ammonia production is one of the big uncertainties in energy system planning. Metal hydride storage technologies like Newcastle’s iron system could influence that outcome by making hydrogen more practical for transportation and energy storage.

The research team is working toward commercialisation through a startup company, HydroStore Technologies, which has raised $8 million in seed funding. They aim to have commercial products available by 2027, initially targeting stationary storage applications before moving to mobile applications like vehicles.

Whether iron hydride storage achieves market success will depend on performance validation, manufacturing scale-up, and competition from alternative storage methods. But it represents promising Australian research in a technology area with potential global impact.