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The promise is enticing, but requires careful reading. The so-called 200 years apply to the demand for hydrogen in the goal of zero emissions, and only if a small fraction of this gas is indeed recoverable. Most of it is too dispersed to be extracted, and the exploration of this clean energy is still in its infancy worldwide.
Rocks billions of years old hidden deep within the Earth may hold one of the largest sources of clean energy on the planet: natural hydrogen. This is a gas that forms when water reacts with iron-rich minerals underground and, according to a study by the United States Geological Survey, could, in theory, supply the hydrogen demand for about 200 years in a low-emission future, sparking enormous interest in the energy sector.
The data comes from a study published in December 2024 in the journal Science Advances, conducted by researchers Geoffrey Ellis and Sarah Gelman from the United States Geological Survey, the USGS. Before getting too excited, however, it’s crucial to understand the size of the caveat: the impressive number depends on conditions that are still far from being confirmed, and most of this hydrogen, according to the authors themselves, will probably never be extractable in a viable way.
What is natural hydrogen
Natural hydrogen, also called white, golden, or geological hydrogen, is formed by natural processes deep within the Earth, unlike hydrogen produced in laboratories or industry, which usually requires a lot of energy or depends on fossil fuels, such as natural gas.
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This is where its great appeal as a clean energy source lies: because it already exists ready in the subsoil, it could, in theory, be extracted with fewer industrial steps, reducing costs and emissions.
When used in fuel cells, hydrogen generates energy by releasing basically water vapor, instead of the carbon dioxide from traditional fuels, which places it at the center of discussions about the energy transition.
How the gas forms in the depths of the Earth
The chemistry behind this phenomenon is as ancient as the rocks themselves.
The main form of generation is a process called serpentinization, in which water penetrates deeply and reacts with rocks and minerals rich in iron and magnesium, breaking water molecules and releasing hydrogen, which can become trapped in fractures and underground reservoirs.
It is estimated that this mechanism accounts for a large part of the Earth’s natural hydrogen.
There is also another process, radiolysis, in which natural radiation emitted by elements in the underground breaks water molecules, generating the gas.
For hydrogen to accumulate, a combination of factors is necessary: ancient and reactive rocks, water circulation through fractures, suitable temperatures, little free oxygen, and geological structures capable of trapping the gas, in an arrangement similar to that which retains oil and natural gas.
The study’s numbers, with due caution
The USGS model estimates that there is a huge amount of natural hydrogen underground, with a most likely value around 5.6 million megatonnes, but with a gigantic range of uncertainty, and the authors themselves state that most of it is too dispersed to be economically recoverable.
The famous 200-year number refers to a specific scenario: if only a small fraction of this total, something like 2% of the central estimate, can actually be extracted, it would already be enough to supply the projected hydrogen demand to achieve carbon neutrality for about two centuries.
In other words, it is not about supplying all the world’s energy, but the specific demand for hydrogen in a low-emission future, and even then only if extraction proves possible.
Where these reserves might be
The search for natural hydrogen has already begun in various parts of the world.
Researchers look for signs of the gas in regions with very ancient crystalline rocks, deep geological belts, and areas with fractures in the crust, using techniques such as measuring gases escaping from the soil, analyzing iron-rich rocks, and exploratory drilling in promising locations.
Some cases have already caught the world’s attention. In 2011, a water well in the village of Bourakébougou, in Mali, released a gas that turned out to be 98% hydrogen, a milestone that changed the way scientists viewed the subject.
More recently, the Lorraine region in France has emerged as one of the most promising, and there are mapped occurrences in countries such as the United States, Australia, Russia, and Oman, although commercial exploration is still in its early stages.
The challenges that still need to be overcome
Despite all the enthusiasm, the path to real utilization is long.
It is still necessary to discover how much hydrogen really exists in accessible locations, whether it renews on a useful scale, if extraction is economically viable, how to store it safely, and what environmental impacts may arise in the process, questions that only more research and drilling can answer over the coming years.
For this reason, the USGS study itself concludes that the subject deserves more investigation, without promising miracles.
Natural hydrogen can indeed become an important part of the clean energy matrix of the future, complementing green hydrogen and other renewables, but it is far from being a magical or immediate solution.
It is a promising opportunity that still needs to move from the realm of potential to commercial reality.
Why this interests Brazil
The subject has direct relevance for a country with Brazilian geology.
Brazil has vast areas of ancient crystalline rocks and geological formations that, in theory, could harbor natural hydrogen, which puts the country on the radar for future research on this resource, at a time when the world is seeking alternatives to reduce dependence on fossil fuels.
Additionally, Brazil is already seen as a potential giant in low-carbon hydrogen, especially green hydrogen, thanks to its renewable electric matrix.
The eventual confirmation of accessible natural hydrogen reserves could add to this scenario, reinforcing the country’s role in the global energy transition.
For now, however, it is a topic to follow with interest and caution, without anticipating results that still depend on a lot of science.
The natural hydrogen hidden in billion-year-old rocks is one of the most fascinating bets in the search for clean energy, with an estimated potential capable of impressing anyone.
Even so, as the USGS scientists themselves show, it is essential to separate enthusiasm from reality: the grand numbers depend on a recoverable fraction that has yet to be proven, and exploration is in its infancy.
If science confirms that it is worth extracting this gas from the underground, the future of energy could indeed be stored in the ancient processes of the Earth. Until then, it is a promise to be observed with curious eyes and feet on the ground.
And you, have you heard about natural hydrogen as a source of clean energy? Do you believe it can really help replace fossil fuels in the future, or do you think it’s still too early to get excited? Leave your comment, share your opinion on the energy transition, and share the article with those interested in science, energy, and the future of the planet.
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