Reservoirs of what’s called geologic hydrogen – an untapped, clean energy source – might be pooling underground in parts of the Bluegrass State, according to research published last year by the U.S. Geological Survey.
While many natural activities produce hydrogen gas in relatively small amounts, researchers in recent decades have discovered that some geological processes create large deposits of it in the Earth’s subsurface.
“It actually is a fantastic energy source because you can burn it and get energy, or you could put it through a fuel cell and directly convert it into electricity,” said Geoffrey Ellis, a research geologist with the USGS. “In either of these processes, you combine the hydrogen with oxygen and you make water [as a byproduct], which is completely benign.”
Using geological surveys, tectonic maps and other data often utilized by the oil and gas industry, a team of USGS researchers in 2025 made a first-of-its-kind prospectivity map of the country to show where they believe the right conditions are at play to generate large amounts of geologic hydrogen.
Ellis said the map lit up places like Kansas and Michigan, but also had bright spots under far western Kentucky.
“I think it's pretty clear that western Kentucky does look quite prospective relative to the rest of the country,” he said. “The New Madrid Seismic Zone … is, in fact, one of the major contributing factors to the prospectivity there.”
The map also indicated a high likelihood of the resource being found under southcentral Kentucky. Ellis and his team believe geologic hydrogen could be in those parts of the Bluegrass State because of the presence of multiple elements needed for one method of hydrogen generation.
Underground water oxides iron-rich rocks commonly found underneath the surface in those regions. That chemical process also creates hydrogen gas, which migrates into the sediment and becomes trapped – potentially accumulating under the surface.
The study of geologic hydrogen, which some call natural or white hydrogen, is a relatively nascent field born out of an accidental discovery nearly four decades ago.
What in the blue blazes?
In 1987, well diggers in the Malian village of Bourakébougou went drilling for water – and they came up empty.
After boring more than 350 feet into the African soil, some of the workers – as told to Science – observed “wind was coming out of the hole.” A driller, investigating, looked into the hole while smoking a cigarette, only for the “wind” to explode in a burst of blue flame.
The worker was badly burned, but neither he – nor the fire – died. Crews worked for weeks to put out the blaze and cap the well, but decades passed before a formal study of the source of the outburst was conducted.
In 2012, a Malian businessman teamed up with a Canadian oil and gas company to drill down on the subject, discovering that the gas coming out of the ground in the village was 98% hydrogen. Within months, the company was burning hydrogen with a retrofitted Ford engine, hooking it up to a generator that gave Bourakébougou its first access to electricity.
The discovery validated a theory that some scientists had long believed: that large stores of natural hydrogen could exist around the globe.
The long-term potential of the resource – as far as USGS is concerned – is massive.
A model presented to the Geological Society of America by Ellis and fellow researcher Sarah Gelman in 2022 hypothesized that there could be enough natural hydrogen percolating underground to meet global power demands for thousands of years.
“As news of that discovery got out, people started realizing that maybe there are more accumulations of hydrogen rich gas, and we just haven't been looking for it in the right place,” Ellis said. “So just in the last five to 10 years, there's been a growing interest in looking at the potential.”
Interest in geologic hydrogen from corporations and governments has grown rapidly in some parts of the country highlighted on the prospectivity map. Within months of the map being published, a company drilling exploratory wells in Kansas said it had found one emanating 96% hydrogen gas. And Michigan Gov. Gretchen Whitmer said in January that she wanted her administration to make the state a hub for the resource, signing an executive order to coordinate efforts across agencies to examine the industry’s potential there.
Ellis said, of the roughly two dozen wells drilled in the U.S. targeting natural hydrogen so far, most were successful in locating the resource – but not in the most convenient, cost-effective form.
“Mostly, companies are finding a lot of hydrogen dissolved in water, which presents a challenge. It becomes expensive if you have to pump water out of the ground and then strip the gas out and then dispose of the water – reinject it or treat it or something. That becomes quite expensive. So that's one of the big challenges associated with geologic hydrogen, is trying to find hydrogen as a free gas.”
According to USGS calculations, about 5.6 trillion metric tons of geologic hydrogen are believed to be trapped beneath the Earth's surface and another 15 million to 31 million tons are formed through various processes each year.
In Canada, the first attempt at drilling a geologic hydrogen well in Saskatchewan hit, with the company behind the project announcing earlier this year that they had found a free gas flow that was a little under 29% hydrogen.
Ellis said it’s hard to predict what the future of geologic hydrogen will be, or even what facilities made to harvest the resource would look like.
Though the resources are quite different, Ellis said the best analog for looking at geologic hydrogen might be shale gas, which Kentucky embraced early on.
“We knew for many, many decades that there was gas trapped in these rocks, and we knew exactly where the rocks were. We just didn't know how to get the gas out, and so it was really an engineering problem of figuring it out,” Ellis said. “For geologic hydrogen, it's a little different. We know how to get the gas, we just don't know where it is … and then if we can figure that out, then we know how to drill it and produce it.”
Digging deeper (figuratively) before digging deeper (literally)
Kentucky’s State Geologist Mike McGlue said that he has “had a number of conversations about it with a bunch of different stakeholders” since the USGS map was published last year, including at least one industry group.
Since then, McGlue said members of the Kentucky Geological Survey have started conducting research using what they’ve learned from the work of Ellis and others, along with the agency’s extensive collection of subsurface data and geological core samples.
“It's certainly early days, and so there's a lot more work that needs to be done to really understand the subsurface and what sort of resource might be present,” McGlue said. “We're really, really stepping through that process now to understand what might be there.”
Within the next couple of years, the state geologist said the agency could begin doing soil gas testing in places like western Kentucky, looking for hydrogen emanations from the ground in places with high prospectivity.
McGlue said, considering Kentucky’s long history with coal, oil and natural gas, the discovery of a naturally occurring carbon-neutral energy source could be a major boon to the state. He said the resource could pay dividends, especially as governments and utilities work to meet rising energy needs.
“It's essentially a contribution of clean energy to the state's energy endowment, which could be tremendously important,” he said. “When you think about energy and energy availability and energy security, it's really interwoven with everything in the country – national security, our economy, our workforce. So if a resource like this did exist in Kentucky, it would certainly be in our best interest to study it and potentially take advantage of it.”
McGlue said he expects to present updated research from his team regarding geologic hydrogen during the Kentucky Geological Survey’s annual seminar in Lexington this June.
