A remote community of mud huts and corrugated iron roofs in the arid savannah of West Africa could be a trailblazer for a new form of carbon-free energy. The residents of Bourakebougou in Mali are the only people in the world who get their electricity by burning natural hydrogen. First identified bubbling from the depths through a village water well in 1987, the gas contains no carbon and, when burned, produces only water.
But the Malian pioneers could soon lose their unique status. Geologists who once dismissed out of hand the idea that the Earth’s crust was widely impregnated with stores of hydrogen, now say there could be trillions of tons of it lying unnoticed beneath the planet’s surface, with more being generated all the time.
In recent months, prospectors have been rushing to find it — drilling for hydrogen in northeast France, Australia, Spain, Morocco, Brazil, and, in the United States, in Nebraska, Arizona, and Kansas. Even Bill Gates has joined the hydrogen rush, making a major investment in a company that is exploring for hydrogen in the Midwest.
Extracting natural hydrogen, a propopent says, “could supply all our hydrogen needs for hundreds of years.”
Proponents are bullish. “Even if we could extract 1 percent of what I believe is down there, we could supply all our hydrogen needs for hundreds of years,” says Viacheslav Zgonnik, a Ukraine-born geochemist who has conducted the most detailed review of the scattered scientific literature on hydrogen finds and is pioneering hydrogen exploration in the U.S. with his Denver-based start-up Natural Hydrogen Energy.
But are such claims well-founded? Will tapping the hydrogen be economic? And is there an environmental downside?
Hydrogen is increasingly seen as a potential substitute for conventional fossil fuels, especially in energy-intensive processes that cannot easily be fueled by electricity, such as blast furnaces, cement works, and industrial heating, and long-distance aviation and shipping. U.S. energy secretary Jennifer Granholm has called it a “game changer [for] delivering a net-zero economy by 2050.”
But until now hydrogen has had to be manufactured, usually by separating it from methane, which requires lots of energy. That means it is only as clean as the sources of energy needed to make it. Most of the 70 million tons of hydrogen currently used globally each year by industry is derived from fossil fuels, giving it a large carbon footprint.
A hydrogen drilling site near Bourakebougou, Mali. Hydroma
Hopes for making greener hydrogen have rested on using renewable electricity from wind or solar farms, or hydroelectric dams, to split water into its oxygen and hydrogen atoms. This process, called electrolysis, is currently more expensive than dirtier methods, however.
But if the manufacture of hydrogen was unnecessary – because there were almost unlimited amounts of naturally generated gas underground just waiting to be tapped using conventional oil-drilling technologies — that could change everything. And there is growing excitement among boosters that the world may be sitting on just such a resource.
Extracting the hydrogen should be easy, say engineers. The gas seeps to the surface whenever it has a chance, so drilling to provide a route may be all that is needed. No fracking is required, though the hydrogen may require purification if it is mixed with other gases.
There is concern among environmental scientists that unleashing this hydrogen into the atmosphere could have unintended consequences.
Yet questions remain about whether energy from natural hydrogen at scale is practical or can be cost-effective. A global review of hydrogen published last September by the International Energy Agency cautioned there was “a possibility that the resource [natural hydrogen] is too scattered to be captured in a way that is economically viable” and that “the exact cost implications remain to be seen.”
There is also concern among environmental scientists that unleashing this hydrogen into the atmosphere could have unintended consequences — including indirect greenhouse warming. “Although it is not a pollutant in its own right,” atmospheric chemist Richard Derwent wrote in a study for the British government, “hydrogen may hasten the build-up of the greenhouse gases … and hence contribute to climate change.”
Geologists have long known that processes in the Earth’s crust can make hydrogen gas from water. The most prevalent way appears to be serpentinization. This occurs when iron-rich rocks such as olivine are in contact with underground water and rust, capturing the oxygen to make iron oxides and leaving behind hydrogen.
Olivine, an iron-rich rock that reacts with groundwater to produce hydrogen. Smithsonian National Museum of Natural History
Until recently this chemical reaction was seen as little more than a geological curiosity. Hydrogen is an extremely light gas, and the assumption has been that it would swiftly seep away into surrounding rocks or the atmosphere, never collecting in useful quantities. Outside Russia — where Moscow geologist Vladimir Larin was making the case half a century ago that we live on a “primordially hydrogen-rich planet” — few researchers showed much interest in exploring whether that assumption was true.
There has been a long-standing belief that “free hydrogen in nature is rare,” says Zgonnik, whose company successfully drilled the first U.S. well to explore for hydrogen in Nebraska in 2019. “If no one expects to find free hydrogen, no one samples for it.”
Zgonnik says this was exacerbated by standard analytical techniques in gas chromatography, which traditionally used hydrogen as an inert gas to carry samples. So, even if the gas was present in a sample, it would not be detected. He says this helps explain why, among more than 100,000 gas samples analyzed by the U.S. Geological Survey (USGS), only eight recorded hydrogen at significant concentrations.
Geoffrey Ellis, a geoscientist at the USGS in Denver, agrees that “geoscientists have not looked for natural hydrogen in the right places with the right tools.” He and colleague Sarah Gelman will shortly publish a new modeling tool aimed at filling the gap.
Fire fueled by hydrogen seeping from Mount Chimaera in Turkey. Evgeny Haritonov / Alamy Stock Photo
Ellis’s early calculations suggest there may be something like 10 trillion tons of natural, or “geologic” hydrogen buried underground worldwide. Many reserves will be too deep or remote to tap easily — around hydrothermal vents in the deep ocean, for instance. But if Ellis is right, then just a small fraction could meet the world’s needs for centuries. And it could in places be tapped for less than $1,000 per ton, says Emily Yedinak of the U.S. Department of Energy’s (DOE) Advanced Research Projects Agency-Energy making it substantially cheaper than manufactured hydrogen.
As well as being cheap and carbon-free, natural hydrogen is also potentially a renewable resource. Ellis estimates that the Earth may generate hundreds of millions of tons of new natural hydrogen annually. But he warns against getting carried away. “I am cautiously optimistic,” he says, “but we need some more data to be convinced.”
Others simply don’t believe it. Stuart Haszeldine, a geologist at the University of Edinburgh, says, “Hydrogen is very leaky. It leaks almost as fast as it is produced, and certainly over geological time, it’s not accumulated to any great extent.”
Zgonnik is enthusiastic, however. He believes these leaking flows can be tapped as well as trapped reserves. “We should tap these flows, or they will continue to leak to the surface and be lost,” he says. The generation process might even be augmented or kick-started, he suggests, by injecting water into iron-rich rocks where there is none.
French geologists claimed last year that they had chanced on potentially the largest known hydrogen deposit to date.
Biologists are finding whole underground ecosystems made up of microbes that obtain their energy from hydrogen. One of the best studied ecosystems feeds on the hydrogen that bubbles out of the hot springs in Yellowstone National Park.
But even if we know hydrogen is down there in vast volumes, geologists still need to pinpoint where the main reserves are, and where the most active generation is taking pace, says Ellis. The handful of discoveries to date have mostly been accidental.
The first — and so far only — natural hydrogen source in regular use is in the village of Bourakebougou, north of the Malian capital of Bamako. It was discovered after the cigarette of an engineer digging a water well set off a small explosion. The well was tapping a shallow underground reserve of almost pure hydrogen.
Since 2012, a company formed by former Malian presidential candidate Aliou Diallo has been capturing the hydrogen from the well at a rate of around 50,000 cubic feet per day. The gas fuels a small turbine that generates power for the village’s 1,500 inhabitants. The company has also worked with Canadian engineers to drill another 24 wells across the surrounding area, finding extensive hydrogen reserves in rock cavities near the surface.
A hydrogen drilling operation in Nebraska. Natural Hydrogen Energy
Three years ago, during Covid lockdown, geologist Luke Titus was rifling through the South Australian state government’s geological archives when he stumbled on documents written by oil prospectors a century earlier reporting the discovery of hydrogen on Kangaroo Island close to the state capital, Adelaide. The rediscovery has triggered a hydrogen rush across the state. One estimate suggests there could be enough hydrogen to power Adelaide for 40 years.
Meanwhile in northeast France, geologists last year claimed they had chanced on potentially the largest known deposit to date — up to 250 million tons of 98-percent pure hydrogen. Jacques Pironon, head of the GeoRessources Laboratory at the University of Lorraine, found the hydrogen while looking for methane in the coal seams of a former mining area. Deeper drilling will be needed to confirm the size of the find, says Ellis.
In the U.S., successful drilling by Zgonnik’s Natural Hydrogen Energy and other companies in Nebraska and Kansas has encouraged others. Bill Gates’s Breakthrough Energy Ventures last year joined a $91 million investment in Colorado-based start-up Koloma, which is hunting for hydrogen along the 1,200-mile Midcontinent Rift south of Lake Superior, through Wisconsin and on to Kansas.
Meanwhile, the DOE in September signed a $20 million deal to explore the source of hydrogen bubbling out of springs in the Gulf state of Oman.
Until now, many of these initiatives have been wildcat gambles, often based on survey work done decades ago for the oil and gas industry.
Until now, many of these initiatives have been wildcat gambles, often based on modelling and survey work done decades ago for the petrochemicals industry. But researchers are racing to find more systematic ways of locating exploitable hydrogen reserves.
Ellis and Gelman’s modeling tool looks first for rocks with the potential to generate hydrogen, and then narrows the list down to places where there are both porous rocks in which that hydrogen could accumulate and neighboring strata that will seal in the gas. They are working on a map showing the best places in the U.S. to look for hydrogen, for publication later this year.
Another approach is to looks for seeps at the surface, which would indicate active generation of hydrogen below ground. Researcher at Ohio State University told the American Geophysical Union in December that AI scanning of satellite images could pin down likely seepage sites by looking for tell-tale elliptical depressions with bleached soil.
Sometimes called “fairy circles,” these depressions typically measure hundreds of yards across. “They are like chimneys for hydrogen exhalation,” says Zgonnik, who published papers a decade ago on their prevalence in Russia and North Carolina, coauthored with geologist Nikolay Larin, the son of Russian hydrogen pioneer Vladimir Larin.
A "fairy circle" in Brazil that has been found to seep hydrogen. Alain Prinzhofer
A research team in Western Australia has recently found hydrogen north of Perth by looking for such depressions. But Ellis remains cautious. He says that “a causal connection between fairy circles and hydrogen seepage has never been established.”
Even if the hype about natural hydrogen proves justified, some researchers warn of environmental downsides. Some hydrogen reserves also contain methane, a virulent greenhouse gas. Any emissions or flaring of this methane could swiftly reduce the benefits of the zero-carbon hydrogen, Stanford energy analyst Adam Brandt recently concluded.
Others have warned that hydrogen leaks from wellheads, pipelines, and other infrastructure would be inevitable, regardless of whether the hydrogen is produced naturally or manufactured. While hydrogen is not itself a greenhouse gas, it has indirect warming properties, warns Ilissa Ocko, a climate scientist at the Environmental Defense Fund.
For instance, some of the hydrogen released will react with the atmospheric compound hydroxyl, creating ozone, which in the lower atmosphere is a greenhouse gas. And by using up hydroxyl, which is the atmosphere’s main cleansing agent, hydrogen will leave less of the organic compound available to break down methane and other greenhouse gases, resulting in those gases lasting longer in the atmosphere and causing additional warming.
The jury is still out on how big a role hydrogen will play in the world’s future energy supplies. But demand is rising fast.
“Hydrogen warming effects have major implications for an emerging hydrogen economy,” says Ocko. But her study only looked at manufactured hydrogen. Zgonnik argues that capturing natural hydrogen as it is generated underground could have the opposite effect, reducing warming. This is because seeps of natural hydrogen are already reaching the atmosphere. “Harvesting it will reduce the seepage, and so will have a beneficial effect on climate.” The same might not apply, however, to tapping reserves contained in the Earth’s geology that would not otherwise leak into the air.
The jury is still out on how big a role hydrogen will play in our future energy supplies. But demand is rising fast, and Ellis believes global consumption of hydrogen is set to increase at least fivefold by 2050. So finding ways of securing low-cost hydrogen is critical. “The timing is right for natural hydrogen,” says Zgonnik, after more than a decade on the case. “We are at the forefront of large-scale development.”
Yet looking at the same evidence, the University of Edinburgh’s Haszeldine concludes that the amount of hydrogen located underground so far is quite small. It may be there, he says, “but at the moment I don’t see it as being a big option for us.”
