Scientists in China have measured record levels of natural hydrogen leaking from the ground in the Sichuan Basin. “Breakthrough” gas samples taken south of Chengdu revealed hydrogen purity between 97.33% and 98.24%, which makes this the highest concentration ever recorded in the country.
“In June 2026, an unidentified gas leak was discovered in the southern Chengdu area of the Sichuan Basin,” noted the researchers in a new study. Subsequent lab tests revealed that the gas consisted almost entirely of pure hydrogen, accompanied only by trace amounts of nitrogen and methane.
“Gas detection work was subsequently carried out at the leak point, revealing a natural hydrogen content as high as 98.24%,” added the researchers. “This not only broke the record for natural hydrogen concentration in China but also became one of the few discoveries globally exceeding 98.00% purity.”
Detailed chemical and carbon isotope tests
To determine how the gas formed, the team carried out detailed chemical and carbon isotope tests on the methane. The extremely low methane levels gave scientists their first major technical clue. These numbers allowed researchers to rule out standard organic decay or high-temperature methane breakdown as the source.
Instead, the gas identification data confirmed that the hydrogen comes from a deep inorganic fluid system within the Earth’s crust. Tests on the trace nitrogen showed that it was not air contamination, but rather fluid produced during deep crustal metamorphism.
The local geology explains how this gas is produced and transported. The leak sits in an area of Permian volcanic rock next to the Shimian-Miaowan Neoproterozoic ophiolite belt. Based on these rock formations, geologists believe that serpentinized peridotite or Permian diabase porphyry acts as an active, continuous underground hydrogen generator.
Bypassing Fischer-Tropsch reactions
Once generated, the hydrogen moved rapidly toward the surface along regional faults. Because this transport happened quickly, the gas bypassed Fischer-Tropsch reactions that would normally turn hydrogen into other hydrocarbons.
For decades, energy geologists thought hydrogen molecules were too small and light to stay trapped underground without leaking away. Most scientists treated natural hydrogen as a rare curiosity rather than a workable energy resource. However, that view has changed in recent years.
In Mali, the Bourakébougou field already produces natural hydrogen commercially at stable concentrations between 97.40% and 98.00%. The new data from Chengdu confirms that cratonic sedimentary basins can also hold high-purity natural hydrogen deposits.
Global shift in energy geology
Global mass balance models estimate that underground natural hydrogen reserves total around 5.6 x 106 Mt (metric megatons). If the energy industry can extract just 2% of that total volume, it would yield twice the energy found in all proven global natural gas reserves.
“In 2023, Science listed ‘Hidden Hydrogen’ as one of the top ten scientific breakthroughs of the year, marking a new stage in natural hydrogen research, moving from accidental discovery to resource exploration,” highlighted the study.
Following their initial field tests, the research team outlined three technical steps to evaluate the Sichuan Basin. Geologists will map deep source rocks, trace migration pathways through fault networks, and run isotope studies to measure the rate of continuous hydrogen production.
