The Albanian mine: "The researchers found that the gas bubbling from the pool was more than 80 per cent hydrogen, with methane and a small amount of nitrogen mixed in. It was flowing at a rate of 11 tonnes per year, almost an order of magnitude greater than any other flows of hydrogen gas measured from single-point sources elsewhere on Earth’s surface. To determine the source of the gas, the researchers also modelled different geological scenarios that could produce such a flow. They found the most likely scenario was that the gas was coming from a deeper reservoir of hydrogen accumulated in a fault beneath the mine. Based on the geometry of the fault, they estimate this reservoir contains at least 5000 to 50,000 tonnes of hydrogen. “It’s one of the largest volumes of natural hydrogen that has ever been measured,” says Eric Gaucher, an independent geochemist focused on natural hydrogen. But it still isn’t a huge amount, says Geoffrey Ellis at the US Geological Survey."

This is the second or third time someone found modest amounts of hydrogen underground, and then started making claims of vast quantities being available. There's been so much well-drilling worldwide for other materials that if hydrogen was anywhere near the surface, it would have been found by now. The "gold hydrogen" enthusiasts claim well depths of a few kilometers are enough. Oil and natural gas wells routinely go that deep.

So far, nobody has a "natural hydrogen" well producing. Even though this startup [1] said they would have one by the end of 2024. Their "news" releases are all about going to meetings, making deals, and such. Not much mention of drilling, unlike the statements they made a few years ago.

There's one well in Mali which yields enough hydrogen to run an auto engine driving a generator. That's it for actual output. That deposit been known since the late 1980s, and invested in since 2012. Exploratory wells were drilled in 2018. Results from that are, somehow, hazy.[2] Not finding followups since 2018.

The hype is strong here.[3]

[1] https://helios-aragon.com/news/

[2] https://www.sciencedirect.com/science/article/abs/pii/S03603...

[3] https://www.scopus.com/record/display.uri?eid=2-s2.0-8518695...