A new scientific paper has dug into an energy treasure trove beneath our feet—natural hydrogen that could power society for the next 170,000 years, and help drive the transition to a low-carbon future.
Published in the journal Nature Reviews, the study, led by a team at the University of Oxford, Durham University, and the University of Toronto, reveals that vast reserves of this naturally occurring gas lie hidden within the Earth’s continental crust, offering a tantalizing prospect for clean, large-scale energy production.
Hydrogen is often touted as the clean fuel of tomorrow, emitting only water when used. But most of today’s hydrogen is produced from fossil fuels, a process that emits significant carbon dioxide. This latest study proposes a much greener way of producing the gas: by leveraging the Earth itself.
Over the past billion years, natural processes in the continental crust have generated enough hydrogen to equal the energy content of 170,000 years of current global oil consumption.
The study identifies two primary mechanisms by which natural hydrogen is created underground. First, water–rock reactions occur when water interacts with iron-rich rocks like peridotite. Chemical reactions oxidize the iron and split water molecules, releasing hydrogen gas. Second, a process called radiolysis is the radioactive decay of elements such as uranium, thorium, and potassium in crustal rocks. As those elements break down, they emit radiation that splits nearby water molecules, producing hydrogen.
While these two processes can take thousands, if not millions, of years, our planet has been quietly running a billion-year-old factory.
The study pinpoints four types of geological settings where hydrogen is most likely to accumulate in commercially viable quantities. These include continental margin ophiolite complexes, which are slices of oceanic crust pushed onto land during tectonic collisions; alkaline granite terranes, which are areas rich in radioactive granites ideal for producing hydrogen through radiolysis; large igneous provinces, which are vast regions of ancient volcanic rock rich in iron and well-suited for hydrogen-generating water–rock reactions; and Archaean greenstone belts and TTG (tonalite-trondhjemite-granodiorite) batholiths, which are among the oldest rocks on Earth and combine both main hydrogen-generating mechanisms.
“Combining the ingredients to find accumulated hydrogen in any of these settings can be likened to cooking a soufflé – get any one of the ingredients, amounts, timing, or temperature wrong and you will be disappointed,” explained lead author Chris Ballentine, from the Department of Earth Sciences at the University of Oxford in a press statement. “One successful exploration recipe that is repeatable will unlock a commercially competitive, low-carbon hydrogen source that would significantly contribute to the energy transition – we have the right experience to combine these ingredients and find that recipe.”
Remarkably, these geological settings are found on every continent, indicating that natural hydrogen could become a globally accessible energy resource rather than restricted to just a few regions.
So can these reserves be tapped? There are some hurdles.
While the implications are profound, most of the hydrogen generated over geological time has likely escaped to the atmosphere or been consumed by subsurface microbes. For hydrogen to accumulate in extractable quantities, several geological “ingredients” must align. High-purity hydrogen accumulations, like the one discovered in Mali in 2018, are rare, and oftentimes, that hydrogen is mixed up with other gases, making extraction complicated.
Moreover, the Earth’s natural hydrogen production is not renewable on human timescales. While the reserves are vast, they are the product of millions of years of slow geological processes. Once tapped and extracted, they’re empty.
That being said, while hydrogen doesn’t spring eternal, hope does.
Natural hydrogen offers a crucial advantage: a very low carbon footprint. Extracting it from underground accumulations could emit as little as 0.4 kg of CO₂ per kilogram of hydrogen—comparable to or better than “green” hydrogen made from renewable electricity, and far cleaner than hydrogen from fossil fuels. Early cost estimates suggest it could be produced for $0.5–1.0 per kilogram, making it highly competitive.
The prospect of tapping Earth’s hidden hydrogen reserves could be a game-changer in the global energy transition. It offers a way to produce clean energy at scale, supporting industries and transport sectors that are hard to decarbonize with electricity alone. If exploration and extraction technologies can be refined, and if enough large accumulations are found, natural hydrogen could become a cornerstone of a future clean energy system.
MJ Banias covers security and technology with The Debrief. You can email him at mj@thedebrief.org or follow him on Twitter @mjbanias.
