Earth may contain vast overlooked stores of hydrogen gas. If some of it is feasible to recover, this natural hydrogen could provide a source of clean-burning fuel that might accelerate the transition away from fossil fuels and last for centuries.
Geologists have known for decades that millions of tonnes of hydrogen gas generated by natural geological processes seeps out of the ground every year, but it wasnât seen as a viable source of energy.
Most geologists assumed the tiny hydrogen molecules wouldnât stay trapped long enough to accumulate in large reservoirs. And what didnât leak into the atmosphere might be eaten by microbes or transformed by other chemical reactions. Even if all the hydrogen known to be seeping out could be captured, it would provide only a fraction of the roughly 100 million tonnes of hydrogen the world currently uses each year, which is mostly produced by reforming methane with steam.
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âIt wasnât a priority because we didnât suspect it could be volumetrically relevant,â says at the University of Texas at Austin, who wasnât involved in the current research.
Revised estimates of how much hydrogen Earth might contain as well as the growing importance of hydrogen for the energy transition could change that view.
and at the US Geological Survey created a model extrapolating from the little that is known about natural hydrogen to estimate how much there is and how much could potentially be extracted for fuel. The research was at a meeting of the Geological Society of America in October 2022.
Their model found there are most likely tens of millions of megatonnes of hydrogen collected in stable deposits within Earth, with estimates ranging from tens of thousands to tens of billions of megatonnes.
âThe first time I saw this and saw the scale I said, âletâs rerun this, and check it,â says Ellis. âBecause thatâs a big number.â
If a natural hydrogen industry grew at a pace similar to that of the natural gas industry, the researchers found natural hydrogen could supply hundreds of millions of tonnes annually by 2100, enough to meet half of projected demand for hydrogen. If it were renewed by geological processes â such as water interacting with iron-rich rocks â they found it could supply hundreds of millions of tonnes each year for centuries.
Ellis says the model contains large uncertainties. For instance, it uses 2.5 billion tonnes as the most likely amount of hydrogen leaking into the atmosphere each year. Actual , while limited, have recorded only around 23 million tonnes, though Ellis says so few measurements have been taken that the true amount is likely to be orders of magnitude higher. And even if there is abundant hydrogen, it might not have accumulated in reservoirs large enough to be worth exploiting.
âWe need to go out and do more measurements on the ground,â says Ellis. The British Geological Survey tells żìĂš¶ÌÊÓÆ” it hasnât conducted research on natural hydrogen since 2005.
Elsewhere, the hunt for natural hydrogen is on. The Chinese government has supported research on natural hydrogen for at least a decade, though no large reservoirs have been found, says at Peking University in China. There are also âdozens of start-upsâ starting to explore for hydrogen, mainly in Australia, but also in the US and in Mali, according to an in Science.
The report finds large oil and gas companies are not yet exploring for hydrogen, but are watching to see if prospectors hit paydirt. Indeed, the gas is sometimes called âgold hydrogenâ.
Moscardelli says natural hydrogen is worthy of more attention, but any claims about its potential to speed up the transition away from fossil fuels are speculative at this point. From the amount that exists to what type of infrastructure would be required to recover it, there are a lot of unknowns. âNo one can really claim they are an expert on this,â she says. âBecause we are still learning.â
