The hydrogen hype moves underground

Posted: March 21, 2025

In many sectors, hydrogen has become the holy grail for decarbonization. The world’s lightest element, many analysts predict it could soon replace fossil fuels in blast furnaces, cement works and power plants, and even fuel planes and ships. 

By 2050, consultancies including PwC and McKinsey reckon hydrogen demand could reach as much as 500 million tonnes per year.  

The problem is that, right now, most of it is manufactured from natural gas, an energy-intensive and polluting process. Green hydrogen made with renewable electricity, on the other hand, is still prohibitively expensive and would require building vast amounts of wind and solar power to work out at scale. 

But what if, instead of going through all that trouble, we could just dig hydrogen out of the ground?

How a hydrogen well in Mali sparked a global gold rush 

In 2012, an oil company prospecting in Mali made an intriguing discovery at an old borehole north of the capital Bamako. Twenty-five years earlier, the well had been abandoned after a lit cigarette caused a small explosion and a weeks-long fire. After a field test, the workers realized why: the gas streaming out of the abandoned well was 98% hydrogen. 

At the time, this struck them as highly unusual. Hydrogen rarely turned up while drilling for oil and, for most geologists, it was barely an afterthought. 

Nevertheless, a small group of scientists had long suspected that large reserves of the gas were lying untapped in geological formations. Since a paper on the Malian discovery was published in 2018, interest in what is now simply known as natural hydrogen has exploded. 

“It’s absolutely incredible and really exponential,” geologist Alain Prinzhofer, lead author on the Mali paper and scientific director of a Brazil-based oil and gas services company, told the journal Science in 2023. 

Most natural hydrogen likely forms through serpentinization, whereby subterranean water meets iron-rich rock, such as olivine, which rusts and creates iron oxides—leaving behind hydrogen in the process. 

The gas can make its way to the surface through permeable rocks but can also become trapped in underground deposits, much like natural gas—although in different places, which is why it is rarely found during traditional drilling. Crucially, its origin means it is potentially renewable and unlimited. 

While it's difficult to project with certainty just how much hydrogen is available in geologic stores, the best estimate is on the order of tens of trillions of metric tons. If even just 2% of these reserves are commercially exploitable, they would provide about twice as much energy as all the Earth's provable natural gas reserves--enough to meet projected hydrogen demand for around 200 years. And such estimates don't even take into account the hydrogen that would continue to be generated over time.

However, experts note that it’s still unclear how much of that potential can be tapped economically, especially if deposits are too scattered. 

That hasn’t stopped the speculators. In fact, the promise of so much renewable fuel sitting undiscovered beneath the surface has sparked a veritable gold rush. By the end of 2023, 40 companies were searching for deposits of natural hydrogen around the world, up from just 10 in 2020, according to research firm Rystad Energy.

They’re hunting for hydrogen in countries including Australia, the U.S., Spain, France, Albania, Colombia, South Korea and Canada. Producers claim they can extract the fuel for about $1/kg, or even less—much lower than the production cost for green or even natural gas-based hydrogen. 

In the US, a start-up called Koloma raised $245 million of venture funding last year to search for and extract geologic hydrogen, attracting investors including Amazon’s climate fund and Bill Gates’ Breakthrough Energy Ventures, which is also investing in other natural hydrogen companies, such as Mantle 8 in Europe. Even conventional energy and mining companies have now gotten in on the rush: both BP and Rio Tinto recently invested in UK-based start-up Snowfox Discovery. 

As Gates told The Economist in 2023: “It could be gigantic or it could be a bust, but if it’s really there… wow!” 

Using Earth as a reactor to produce geological ammonia 

If simply pulling green hydrogen out of the ground sounds too good to be true, some have even gone a step further. 

In January, researchers at MIT published a study showing that, with a little help, the geologic hydrogen could be coaxed into producing ammonia—an important ingredient in fertilizers and a fuel in its own right. Crucially, it’s also easier and cheaper to store and transport than hydrogen. 

In the lab, the researchers crushed up iron-rich minerals and added nitrates and water laced with copper and nickel catalyst particles. Then they raised the temperature and pressure to get the hydrogen and nitrogen atoms in their mixture to bond into ammonia.  

Their theory is to simply use the conditions already present below the surface as a reactor. As with natural hydrogen, pulling it out of the ground would eliminate the need for today's emissions-intensive production process. 

“Earth can be a factory for chemical production,” Iwnetim Abate, an MIT professor and author of the study, told MIT Technology Review. “As you dig, you get heat and pressure for free.” 

Once scaled up, the researchers estimate that one well could produce 40,000 kilograms of ammonia per day with their process—although a lot of questions still need to be resolved during field tests. Abate has cofounded a company, Addis Energy, with $4.25 million in pre-seed funds to commercialize the technology. 

One advantage the company is banking on is that its process uses existing technology from the oil and gas sector, specifically drilling and fracking operations. In their search for geologic hydrogen, startups and scientists are also employing seismic mapping, satellite imaging and AI-assisted tools borrowed from the energy sector. 

For now, finding the best deposits is still one of this burgeoning industry’s biggest obstacles. In February, a team of scientists around Frank Zwaan, a geologist at the Helmholtz Centre for Geosciences in Germany, reported using tectonic plate modeling to pinpoint promising regions. 

They found that some mountain ranges—such as the Pyrenees, the European Alps and parts of the Himalayas—offered good conditions, with large volumes of iron-rich mantle rock, favorable temperatures and water circulating through deep faults. 

A few weeks earlier, the U.S. Geological Survey published a map of the U.S. indicating viable hydrogen prospecting areas—the first of its kind at continental scale. It shows several promising parts of the country, from a mid-continent region that covers Kansas, Iowa, Minnesota and Michigan, to the California coast and areas along the Eastern seaboard. 

Meanwhile, back in Mali, that first hydrogen well is now producing enough fuel for a small turbine that generates power for the village’s 1,500 inhabitants. The company formed around it has drilled dozens more and claims to have turned up extensive reserves. 

If all the hype still seems premature, natural hydrogen enthusiasts like to point towards the early history of the very fuel it could help to displace. “Oil was somewhat of a curiosity until the technique was ready for it to be applied on a large scale,” Geoff Ellis, one of the USGS geologists behind its map and research, recently told CNN. Natural hydrogen, he added, could “follow a similar pathway.”