Geological fieldwork occasionally happens in dangerous places, from the slopes of erupting volcanoes to the depths of frigid Antarctic chasms. Even so, they tend not to take place inside exploding mines.
That, however, is exactly where a team of scientists went exploring: the Bulqizë chromite mine in Albania, just northeast of the capital Tirana. And instead of looking for valuable minerals or beguiling rock formations, they were seeking the source of those explosions: almost-pure hydrogen gas—a potentially renewable energy source that could transform the world.
As reported in a recent study in the journal Science, the team found it. Deep below ground, they encountered a small pool effervescing like a frenzied jacuzzi. “The gas was really intense,” says Bardhyl Muceku, a geologist at the Polytechnic University of Tirana and one of the study’s authors. About 84 percent of the gas was hydrogen—and this was one of several seeps in the Bulqizë mine that, in total, was venting at least 200 tons of hydrogen every single year.
The world is several years away from being able to extricate meaningful volumes of natural hydrogen gas from the earth cheaply, cleanly, and efficiently. First, those reservoirs need to be found.
“There’s a lot of work to be done,” says Geoffrey Ellis, a petroleum geochemist with the U.S. Geological Survey who wasn’t involved with the work. But discoveries like Bulqizë are cause for optimism that there may be enough hydrogen trapped underground to power the planet. “This could work,” he adds.
The rise of hydrogen
Hydrogen is the most commonplace element in the cosmos, but it’s hard to find on Earth. When not bound up in other compounds, it’s a colorless gas that likes to escape skywards. That’s a shame, because if we could capture it, it could help transition the warming world away from fossil fuels.
“It can be used as a low-carbon energy store,” says Katriona Edlmann, a geo-energy expert at the University of Edinburgh who wasn’t involved with the work. “You can burn it, and it just produces water. Or you can use it in fuel cells, and it produces electricity. And it can be deployed in the same ways as natural gas.”
Humanity has known that hydrogen has been seeping out of the planet for ages. “We’ve known about hydrogen seeps for thousands of years,” says Edlmann—small gassy pockets topped with endless flames can be found across the globe. But it was always thought that the subsurface contained tiny amounts of the stuff.
“The assumption was that you could never get accumulations of it,” says Ellis. Hydrogen gas, as a molecule, is small, light, and diffusive, so scientists reasoned that any underworld caches should have leaked into space long ago or were otherwise eaten by certain types of microbes that use hydrogen for energy.
The petroleum industry was also not on the lookout for hydrogen. They would sometimes stumble across it while questing for oil or methane gas deposits, but “they just didn’t report it, or they buried it in some company report,” says Ellis. “They weren’t interested. It wasn’t what they were looking for.”
Today, in some settings, hydrogen is used as a minor energy or electricity source—but it must be manufactured. There are myriad ways to do this, from using solar power to electrically sever hydrogen from water molecules, to using steam to extract hydrogen from methane gas.
But these methods are either prohibitively expensive, prone to releasing greenhouse gases, or both. “Cheap hydrogen is the main step towards a hydrogen economy,” says Ali Hassanpouryouzband, a sustainable energy scientist at the University of Edinburgh who wasn’t involved with the work. And presently, that doesn’t exist.
In an ideal world, pure hydrogen gas extracted from below ground would be the most cost-effective way to obtain the valuable substance. But that world long appeared fictional—that is, until 2012, when a sizable hydrogen gas reservoir was found in Mali. More pockets of hydrogen have been found since, including some in Europe and South America. Now, the notion that hydrogen gas couldn’t be trapped below ground “doesn’t seem very well justified,” says Ellis.
Hydrogen hunters
Where else might hydrogen be imprisoned? Prospectors can’t randomly search for it. First, they require clues as to where it’s made—and that means they need to know how Earth makes it.
Although some microbes are known to produce the gas, hydrogen hunters tend to focus on geologic manufacturers. Iron or magnesium-rich volcanic rocks in the presence of (ideally hot) water, which can emit hydrogen. The natural radiation emanating from certain rocks can also split water to forge hydrogen. And Earth’s deeper viscera, including its putty-like mantle, may hold stores of “primordial hydrogen that’s been trapped since the Earth first formed,” says Ellis—and deep fractures tearing into the crust may release it to the surface.
Albania’s Bulqizë mine was a prime target for prospectors for two main reasons. Firstly, it cuts into an ancient seafloor dating back to the time of the dinosaurs—one that is riddled with both fluids and iron-rich volcanic rocks, making it a promising hydrogen factory.
Secondly, it has exploded on several occasions—in 2011, 2017, and 2023. Flammable gas was initially reported in 1992, but even after the first few blasts, methane was presumed to be the culprit. “In the beginning of these accidents, they didn’t know that it was hydrogen,” says Muceku.
Although some methane was detected by scientists in Bulqizë, most of the escaping gas was hydrogen. At a minimum of 200 tons per year, this is one of the most prolific hydrogen seeps ever found.
Hints of a hydrogen future
But the fact that hydrogen was found isn’t what’s got everyone excited. “It’s not a huge amount,” says Muceku. His team estimate that the mine contains a total of 5,000 to 50,000 tons of the volatile vapor. Caches of millions of tons of imprisoned hydrogen gas are what energy-focused prospectors are questing after.
What truly matters here is that the gas was able to be trapped: it had an effective rocky seal, and it wasn’t eaten up by hydrogen-hungry microbes nor did it get broken down by unhelpful geologic reactions.
“This accumulation had to have formed over a period of probably tens of thousands of years,” says Ellis. And, Muceku explains, it was only when the mine cut to depths of around 2,000 feet that hydrogen gas began to escape and cause accidental explosions. The excavations appear to have fractured the roof of a concealed reservoir, one whose deep faults funneled vintage hydrogen from deep within the seafloor slab to the mine above.
Exhumed seafloor slabs were always high-priority targets for hydrogen gas hunters—but this study has underscored that notion. Perhaps the beginnings of a new low-carbon, hydrogen-powered era can be found in similar sorts of tectonic sarcophaguses all over the world.
That story is just starting to be written. It remains uncertain whether Earth’s natural hydrogen reservoir is big enough for the world’s energy needs. Even if it is found to be the case, the technological means of efficiently extracting this gas—and methods of speeding up its geological production—are prototypical.
What matters most is finding those hydrogen reservoirs and, hopefully, finding them full. And right now, geologists are just scratching the surface.
“We have to go deeper to see the potential,” says Muceku.
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