Hydrogen discovered in Albanian mine provides clues on where to find massive hydrogen flows.

The world's largest natural flow of highly pure hydrogen gas has been quietly seeping through a nondescript pool deep within an Albanian chromium mine. Researchers reported the study in a paper published in the journal Science, noting that the investigation of similar deposits may reveal more major findings of this clean-burning resource across the globe.

Naturally occurring hydrogen as a clean fuel alternative can produce energy without generating carbon dioxide (CO2) as a byproduct, especially in energy-intensive processes that cannot easily converted to electric, such as blast furnaces, cement works, industrial heating, long-distance aviation and shipping.

Until recently, the assumption has been that the gas's high reactivity prevented it from accumulating in large underground deposits.

Scientists first took notice of a contradiction to this theory in 1992 when a flammable, odorless gas was first detected in the Bulqizë mine in Albania.

A series of explosions beginning in 2011 and continuing over the following years increased suspicions that the gas was hydrogen, and researchers are now developing a theory that the mine sits atop a fault that contains anywhere from 5,000 to 50,000 tons of the resource.

The study's authors have since determined that the composition of gasses is 84% hydrogen, combined with methane and nitrogen. Overall, Bulqizë demonstrates a remarkably high outgassing rate of 200 tons per year, minimally – the highest recorded natural hydrogen flow to date.

"Our study unveils a high emission rate of almost pure geologic H2, suggesting the potential for a new extractable primary energy source," the paper explained.

While the purity and mass of natural hydrogen in this setting are impressive, the study notes that the Bulqizë chromite mine is located within a stretch of iron-rich rock known as ophiolite, which is known to generate hydrogen as it reacts with water. Similar geological formations are fairly widespread, and several are known to host hyperalkaline sources bubbling with hydrogen.

The study's authors speculate that significant natural hydrogen deposits may lie undiscovered across the globe beneath other ophiolite outcrops, speculating that "[O]phiolites, which are mantle rocks from the oceanic crust obducted onto continents, not only constitute effective source rocks, but also have the potential to host high-quality, H2-rich gas reservoirs."

Conversely, the authors note that geologic hydrogen may not technically be considered renewable, as the time inherent in natural hydrogen production far exceeds extraction time. These geological environments also were discovered to host subsurface biospheres that rely on hydrogen as an energy source.

Other hydrogen proponents like Geoffrey Ellis, a geoscientist at the USGS in Denver, have suggested there may be upwards of 10 trillion tons of geologic hydrogen buried underground worldwide. Ellis also estimates that the Earth may generate hundreds of millions of tons of new natural hydrogen annually, which would be enough to satisfy global needs without taxing the planet.

"Therefore, we also deliver a message of caution to temper the passion, and even sometimes the 'hydrogen fever,' that will undoubtedly be stimulated by our discovery," the authors concluded. "While geologic hydrogen exploration warrants great scientific efforts, we must also be mindful of its potential environmental impact."