Western Australia’s vast iron-rich rock formations may contain more than valuable iron ore.
New research from Edith Cowan University suggests that these ancient rocks can also form hydrogen naturally underground – opening the door to a new low-emission energy source.
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The study was published in the International Journal of Hydrogen Energy under the title “Geometry-driven controls on hydrothermal natural hydrogen generation from magnetite mineral”. The researchers focused on magnetite, an iron-rich mineral found in large quantities in Western Australia’s banded iron formations.
Hydrogen is attracting increasing interest as an energy source, because it can be used without producing carbon dioxide where it is used. Today, however, much of the world’s hydrogen comes from fossil fuels, which can result in significant greenhouse gas emissions.
Natural hydrogen offers another opportunity. Instead of producing the gas at an industrial plant, companies could potentially find hydrogen that has already formed naturally underground – or facilitate geological reactions that produce it continuously.
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The ECU researchers investigated one of these reactions. Magnetite can react with hot water under specific underground conditions and release hydrogen gas. Western Australia is particularly interesting because the Pilbara houses some of the world’s largest iron-rich geological formations.
To replicate the conditions deep below the surface, the researchers placed magnetite samples in water that was heated to 200 °C and kept under high pressure for 60 days. The experiment allowed the team to observe how the hydrogen was formed, and what characteristics of the rock affected its production.
The researchers also investigated whether the natural reaction could be stimulated. They found that injecting a solution into banded iron formations could increase hydrogen production – suggesting that future projects may not need to rely entirely on hydrogen that has already accumulated underground.
Associate Professor Alireza Keshavarz said the potential resource could be very large. If the process can eventually be developed in an economical and safe way, naturally produced hydrogen could contribute to Australia’s domestic energy supply and perhaps also support exports.
Lead author Kaveh Moghanirahimi said Western Australia’s extensive banded iron formations make the state a particularly promising place to explore the idea. A local hydrogen resource could additionally bolster energy security by reducing reliance on imported fuel during supply disruptions.
But the study showed that it is not enough to simply locate a rock formation rich in magnetite. The physical structure of the underground rock can be just as important as the mineral content.
Water must be able to reach fresh magnetite surfaces for the chemical reaction to continue. Cracks, pores and interconnected paths inside the rock therefore affect how much water can move through the formation, and how much hydrogen can be formed.
This finding helps explain why two areas with similar amounts of magnetite can produce very different amounts of hydrogen. A tightly sealed formation can limit contact between hot water and the mineral, while a more fractured and permeable formation can provide much better access.
Professor Stefan Iglauer said the research helps link controlled laboratory experiments to the far more complicated conditions found underground. Real-world geological formations vary in temperature, pressure, water chemistry, mineral composition and structure – all of which can affect hydrogen production.
The idea is still in its early stages. The fact that hydrogen is produced in the laboratory does not automatically mean that commercial quantities can be produced underground, efficiently collected and delivered at a competitive price. The researchers will need field studies to determine how much hydrogen can actually be produced and recycled.
There are also practical issues related to drilling, movement of subsurface water, long-term production rates and environmental impact. Any future industry must show that stimulating the geological reaction does not create unacceptable risks or require more energy than the hydrogen can provide in return.
Nevertheless, the study points to a potentially important benefit for Western Australia: the geology is already known to contain large amounts of the mineral needed for the reaction. The state also has decades of experience in large-scale resource development, which could contribute to future exploration if natural hydrogen proves commercially viable.
The discoveries should therefore be seen as evidence of geological potential – not as evidence of a new energy industry. The laboratory results show that magnetite can form hydrogen under realistic heat and pressure conditions, and that the structure of the rock largely controls the process. The next big test will be whether the researchers can recreate useful production rates in real underground formations.
If this can be achieved safely and economically, the consequences could be significant. Naturally formed hydrogen could become another alternative in the transition to lower-emission energy – while also giving Western Australia a new use for geological formations that are already known for their iron resources.
