Vast reserves of clean hydrogen fuel could be hiding beneath our feet

• Clean hydrogen fuel may occur naturally in large underground reservoirs across the planet.
• Big companies, startups, and the US government are all trying to tap into this carbon-free fuel.
• It's unclear how much natural hydrogen exists, where it is, or if it's economic enough to drill.

Believe it or not, drilling for a certain type of gas could open up a new world of clean energy.

Trillions of tons of lightweight, energy-dense hydrogen gas may be hidden deep underground. Those natural reservoirs, known as geologic hydrogen, could be a fruitful carbon-free fuel source.

Geologic hydrogen is so promising that Bill Gates, Amazon, and United Airlines are just some of the funders behind a startup called Koloma, which thinks it can tap into those reserves. Oil and gas giants BP and Chevron have joined a consortium to study geologic hydrogen. Even the US Senate Energy and Natural Resources Committee is interested. It held a hearing on the subject last week.

"The vast majority of the in-place hydrogen is likely to be in accumulations that are too deep, too far offshore, or too small to ever be economically recovered," Geoffrey Ellis, a USGS geologist, said in the February 28 hearing. "However, if even a small fraction of this amount could be recovered, that would constitute a significant resource."

Hydrogen burns clean, but manufacturing it takes a lot of energy and expense, and even creates carbon dioxide. Still, it's a key pillar of President Joe Biden's clean-energy strategy, which is pumping $7 billion into seven hydrogen hubs across the country.

Drawing from natural reservoirs of hydrogen would be much cleaner — if it's worth the drilling.

A hydrogen gold rush is beginning

It's a relatively new prospect. In fact, scientists didn't believe it was possible for large amounts of hydrogen to accumulate underground until about 12 years ago, according to Ellis, who leads USGS efforts to map the world's potential reserves of underground hydrogen.

That's when an oil and gas company assessed a mine that had exploded in Mali and found it was full of hydrogen gas.

Hydrogen forms deep underground when water reacts with iron-rich rock. In the US, two long stretches of this rock are a promising place to look for hydrogen reserves, and efforts are already underway.

One stretch runs from Kansas up to Ontario, then down to Michigan. The other is offshore, running the length of New Jersey to Georgia, according to Ellis. USGS started looking for these reserves in 2021 and has drilled several wells, with more planned this year.

Ellis told the Senate committee that research is also ongoing in France and Australia, and active exploration efforts are underway in Brazil and Colombia. In February, researchers announced they had discovered a hydrogen reservoir in a mine in Albania.

"Companies exploring for geologic hydrogen use many of the same technologies that are used in the oil and gas industry," Senator John Barrasso (R-WY) said in the hearing. "In fact, many of the people exploring for hydrogen today spent their careers exploring for oil and gas."

It's still unclear how much hydrogen is out there, or how much it will cost to extract it. So the DOE's Advanced Research Projects Agency-Energy is doling out $20 million in grants to fund research on the subject, including the possibility of artificially stimulating the natural process that makes hydrogen underground.

"If our programs show success, this new source of hydrogen could lower energy costs and increase our nation's energy security and supply chains," Evelyn N. Wang, director of ARPA-E, told the Senate committee.

Even so, the fuel would face some of the same challenges as manufactured hydrogen. There may not be enough infrastructure to transport it far and wide. In the process, any hydrogen that leaks into the atmosphere would react with other compounds to cause the atmosphere to trap more heat. That could cancel out hydrogen's climate advantage over fossil fuels.

"Nobody has all the answers today," Koloma CEO and cofounder Pete Johnson told the Senate committee. "But the early data looks very promising and I believe that geologic hydrogen can play a very large role as we work to decarbonize the US energy economy."