“The search for geologic hydrogen today is where the search for oil was back in the 19th century—we’re just starting to understand how this works,” said Frédéric-Victor Donzé, a geologist at Université Grenoble Alpes. Donzé is part of a team of geoscientists studying a site at Bulqizë in Albania where miners at one of the world’s largest chromite mines may have accidentally drilled into a hydrogen reservoir.

The question Donzé and his team want to tackle is whether hydrogen has a parallel geological system with huge subsurface reservoirs that could be extracted the way we extract oil. “Bulqizë is a reference case. For the first time, we have real data. We have a proof,” Donzé said.

Greenish energy source

Water is the only byproduct of burning hydrogen, which makes it a potential go-to green energy source. The problem is that the vast majority of the 96 million tons of hydrogen we make each year comes from processing methane, and that does release greenhouse gases. Lots of them. “There are green ways to produce hydrogen, but the cost of processing methane is lower. This is why we are looking for alternatives,” Donzé said.

And the key to one of those alternatives may be buried in the Bulqizë mine. Chromite, an ore that contains lots of chromium, has been mined at Bulqizë since the 1980s. The mining operation was going smoothly until 2007, when the miners drilled through a fault, a discontinuity in the rocks. “Then they started to have explosions. In the mine, they had a small electric train, and there were sparks flying, and then… boom,” Donzé said. At first, Bulqizë management thought the cause was methane, the usual culprit of mining accidents. But it wasn’t.

Hydrogen at fault

The mine was bought by a Chinese company in 2017, and the new owners immediately sent their engineering teams to deal with explosions. They did measurements and found the hydrogen concentration in the mine’s galleries was around 1–2 percent. It only needs to be at 0.4–0.5 percent for the atmosphere to become explosive. “They also found the hydrogen was coming from the fault drilled through back in 2007. Unfortunately, one of the explosions happened when the engineering team was down there. Three or four people died,” Donzé said.

It turned out that over 200 tons of hydrogen was released from the Bulqizë mine each year. Donzé’s team went there to figure out where all this hydrogen was coming from.

The rocks did not contain enough hydrogen to reach that sort of flow rate. One possible explanation is the hydrogen being released as a product of an ongoing geological process called serpentinization. “But for this to happen, the temperature in the mine would need to reach 200–300 degrees Celsius, and even then, it would not produce 200 tons per year,” said Donzé. “So the most probable was the third option—that we have a reservoir,” he added.

“Probable,” of course, is far from certain.

https://arstechnica.com/?p=2005627