Could Underground Hydrogen Reserves Put Clean Energy Within Reach?

12:03 minutes

White safety helmet is in the hands of an engineer on site.
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In 1987, a crew in the village of Bourakébougou, Mali, was digging for water. After drilling 108 meters deep, they still hadn’t found any, but the resulting borehole produced a steady stream of wind. When a driller lit a cigarette near the hole, the wind ignited, burning the worker. It took weeks for the crew to put out the blue flame, which produced no smoke, and they eventually capped the hole. It remained sealed until 2012 when a local oil and gas company reexamined it and found that the original crew had stumbled upon an underground store of naturally occurring hydrogen. They converted a Ford engine to burn the gas and soon connected it to a generator, providing electricity for the village.

Hydrogen has long been touted as a source of renewable energy with the potential to replace fossil fuels to power transportation and factories. When burned, its only output is water—with no carbon emissions—making it extremely attractive as a clean energy source. But producing commercial hydrogen involves splitting water molecules into their hydrogen and oxygen components, an energy-intensive process typically powered by fossil fuels.

But splitting water isn’t the only way to get hydrogen: It also occurs naturally in underground reservoirs when water heated by the planet’s mantle mixes with iron-rich rocks. The oil and gas industry hasn’t prioritized the search for these underground stores of hydrogen, but more of them have been found lately, including a potentially massive one in Lorraine, France that was discovered last year.

Dr. Geoffrey Ellis, a research geologist at the United States Geological Survey, joins Ira to talk about hydrogen’s potential as a clean fuel, why finding stores of it has been a lower priority than finding oil and natural gas, and the hurdles the industry faces as it aims to expand.

Correction: In the original segment, our guest stated that there may be as much as 500 million megatons of hydrogen in the Earth’s crust. This number is incorrect, the actual estimate is 5 million megatons. The audio has been updated to reflect the correct number.

Further Reading

  • Read this feature from Science about hydrogen hidden underground.

Segment Guests

Geoffrey Ellis

Dr. Geoffrey Ellis is a research geologist with the USGS in Denver, Colorado.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll take a look at the state of science journalism and how the body changes in space.

But first, last year, scientists discovered a potentially massive deposit of hydrogen gas in Lorraine, France. Now, why is this important? Because hydrogen is one of the cleanest burning fuels in nature. It produces no– I mean zero– greenhouse gases when it burns. I mean, when you add hydrogen to oxygen, what do you get? H2O water and heat. That’s it, pure and simple.

And hydrogen is the main ingredient in fuel cells, which produce clean green electricity. You may have heard of hydrogen as a potential clean energy fuel. But here’s the rub, its normal production process is expensive. It usually requires fossil fuels to make it. Ultimately, making it a not so clean fuel.

That’s why there is excitement in the world of hydrogen these days because of the discovery of underground naturally occurring reservoirs of hydrogen, like the one found in France. Historically ignored by the oil industry, these reservoirs have seen increased interest from hydrogen fuel startups as a sustainable alternative energy source. But despite its potential to replace fossil fuels, logistical challenges remain.

But could this new method of acquiring the clean gas help elevate hydrogen fuel into the mainstream? Here to tell us all about the current state of what is called white hydrogen, natural hydrogen, and the hurdles its industry faces is my guest Dr. Geoffrey Ellis, research geologist at the famous US Geological Survey. Welcome to Science Friday.

GEOFFREY ELLIS: Thank you, Ira it’s great to be here with you.

IRA FLATOW: I mean, why have I never heard about large deposits of hydrogen before?

GEOFFREY ELLIS: Yeah, it’s really a curious thing. And in fact, if you had asked me about this four years ago, I would have told you that natural hydrogen accumulations don’t exist in the subsurface. And I think that one reason for it is that we rarely find natural hydrogen in association with natural gas when we explore for oil and gas. And hydrogen leaks out very easily. And so you can’t just trap it in places for very long.

But there was an accidental discovery of an accumulation of natural hydrogen in the country of Mali in West Africa about 10 years ago. And then as news of this discovery got out, people started looking back at old records and realizing that, actually, hydrogen had been found in a lot of places where we previously really just hadn’t taken notice of it.


GEOFFREY ELLIS: And part of the reason I think, also, is that there really wasn’t a market for it. So when oil and gas companies drilled a well and if they found hydrogen, it wasn’t something that they were targeting and it wasn’t something they could sell. And so they walked away from that. And so now people are looking back through old company records and recognizing that, oh, they found this in a number of places.

And in fact, just late last year, a company in Australia drilled two wells in the state of South Australia on sites that, historically, 100 years ago, companies had found hydrogen in the subsurface. And again, they found high concentrations– more than 70% hydrogen gas in these reservoirs.

IRA FLATOW: No kidding.


IRA FLATOW: OK, tell me how hydrogen is produced underground. I don’t understand that.

GEOFFREY ELLIS: Yeah, so, in fact, there are dozens of natural processes that are capable of generating hydrogen in nature. But in order to form economic accumulations of hydrogen, you need a process that can generate fairly large volumes. And so there’s really only a handful of processes that we think would be able to do that.

And the first one is– it involves the reduction of water by iron-rich minerals. And we see high concentrations of hydrogen being generated there naturally. And this process actually occurs in many other places in the subsurface in the Earth’s crust.

IRA FLATOW: Wow, and the advantage of this is that it’s made naturally, right? It’s not made from fossil fuels as hydrogen is done industrially.

GEOFFREY ELLIS: No, absolutely. That’s totally correct. In some ways, it’s somewhat analogous to geothermal energy because you have hot water that has all this energy in it. But in this case, that energy is then converted into hydrogen, essentially, which is then a gas that we could use as an energy resource.

IRA FLATOW: Is it possible to actually have an impact on our use as a green fuel? I mean, is there enough of it?

GEOFFREY ELLIS: Yeah, that’s a great question, and certainly one that we all would like the answer to. And I’ve done some work with a colleague of mine trying to put together a global model of what we think the in place resource might be and what’s most likely to be there. It comes out to the order of about 5 million megatons. And so a megaton is a million metric tons.

IRA FLATOW: Is that a lot when we talk about where it stays in relation to oil or natural gas?

GEOFFREY ELLIS: Yeah, great question. So to give you some context, today in the world we generate about 100 megatons per year of hydrogen from fossil fuels as you noted. And it’s thought that going forward that most of that hydrogen is actually used to upgrade petroleum in the petroleum refining process.

But as we go forward, as we move away from fossil fuels, we’ll be using less hydrogen for petroleum processing, but actually more for energy things, things like aviation and perhaps marine shipping and things like that. And it’s thought that to get to net zero, we’ll probably need about 500 megatons per year of hydrogen to meet the demand for these hard to abate emissions.

And so, as I said, we think there may be as much as 500 mega tons of hydrogen in the Earth’s crust. But we’ll need maybe 500 mega tons per year. But there’s a really important consideration when we think about this global model. This is for the entire Earth’s crust. And so most of that hydrogen is going to be in inaccessible. It’s just going to be in accumulations that are much too deep, or too far offshore, or much too small, that they would never be economic to actually to drill and produce.

But if we think, for a second, if maybe just 2% of that 5 million mega tons were actually shallow enough and big enough accumulations that could be economic, that would actually supply all of that 500 mega tons per year for 200 years.


GEOFFREY ELLIS: And so it seems that actually, in fact, it’s very likely that there is potential for a significant contribution there.

IRA FLATOW: But so far, it’s just startups– small little companies that are looking for these underground stores of hydrogen. The big companies are staying on the sidelines, right? Are they waiting for it to become mainstream and then they’ll buy it out?

GEOFFREY ELLIS: Yeah, that’s a fairly accurate assessment that, yeah, they’re taking a wait and see attitude. This is viewed as high risk certainly at this point. And so the venture capitalists and the startup companies are the ones that are willing to take those kind of risks. The big companies are waiting, watching, and then they’ll move in later, I think, when they see that the risk has reached a lower level.

IRA FLATOW: But there are other challenges, right? Once you get it up and out of the ground, how you store it and move it is also a challenge.

GEOFFREY ELLIS: Yeah, so hydrogen does have some important limitations. As you noted, it is a very clean fuel. It’s very attractive from that standpoint. But it has a fairly low energy density per unit volume. And so in order to efficiently transport it, you need to either compress it or liquefy it. Then you can more efficiently transport it. And of course, that requires more energy input, so that reduces the value of the product.

Now, one important consideration about natural hydrogen is you mentioned that you’d have to store the hydrogen. But in the case of natural hydrogen, it’s already stored in the ground. And so this has the advantage that you can simply open a valve when you need it and then close the valve and leave it underground. So it has the built-in storage aspect.

IRA FLATOW: Do we know how to search for it? You said it was discovered accidentally, right?

GEOFFREY ELLIS: Yes. Yeah, in fact, all of the discoveries to date have been accidental. There’s only been one well that was drilled explicitly targeting natural hydrogen exploration. And they did find natural hydrogen, but we still don’t know exactly what amount there– the company is still working on testing that well. And so, yeah, so far, we’ve only really had these accidental discoveries.

And so the short answer is, no, we don’t really know how to explore for it yet. That’s something that we’re working on now. We have groups in France and Australia and now here in the US. The USGS, in fact, has a big program now working on trying to understand how can we better understand the resource potential and then also develop tools and techniques and strategies for exploring for natural hydrogen.

IRA FLATOW: So is it being taken seriously now?

GEOFFREY ELLIS: I think it absolutely is, yeah. Just in the last couple of years, it’s really moved from a fringe topic with a very small group of researchers working on this to it seems to have moved more into the mainstream and gotten wider acceptance among geoscientists as they learn about it and understand the potential here.

IRA FLATOW: So you’re optimistic about this.

GEOFFREY ELLIS: I am optimistic. I think there’s a lot we need to learn. There’s a lot of work that we need to do. But there’s great potential here. And we just have barely scratched the surface yet. And so we need to do the work to really realize what that potential is. But there’s a lot of potential.

IRA FLATOW: Yeah, you’ve barely scratched the underground–


IRA FLATOW: –so to speak. That’s, I guess, a geology bad joke.



IRA FLATOW: And when you’re talking about using this hydrogen, are you thinking about burning it or using it to make electricity in, like, fuel cells?

GEOFFREY ELLIS: Yeah, so I think most people think that applications that can easily be electrified– things like we now have efficient battery-powered cars that can run on electricity. And so we probably won’t use hydrogen for running our cars anytime soon.

But there are sectors like aviation that, from what I understand, nobody thinks that we’re really going to be able to have 747s that are battery-powered that can fly across the Atlantic Ocean. And so they’re looking at hydrogen for fueling things like that– aviation, long-distance marine shipping.

And so in those applications, it would likely be just directly burning hydrogen or running it through a fuel cell and then running electric motors that way. But if we found significant resources underground, I think that then that would broaden the application, especially if there are resources that are close by to places where we need to use the energy.

IRA FLATOW: What country is way ahead in hydrogen development?

GEOFFREY ELLIS: Yeah, so I would say really Australia is probably the leader right now where we see the most activity going on. There’s a number of research groups that are working actively. And as I mentioned, we had a couple of wells that were just drilled late last year that made new discoveries.

So yeah, Australia is certainly very active. But there’s also exploration going on in France. As you noted, the discovery in Lorraine. And they recently permitted exploration license in the Pyrenees in the South of France. And Brazil is also another area that’s quite active.

And in the US, actually. We’ve been kind of late to the game, actually. The French and the Australians have been doing research in this area much longer than we have. But companies have moved into the US because it’s a good climate. We have a lot of infrastructure for drilling wells, companies that are capable of doing this kind of work and a lot of experience in working in the subsurface, as well as a relatively amenable regulatory environment.

So the companies are interested in working here. So we’ve had this one well drilled in Nebraska, and then there will be a couple more wells drilled in Kansas sometime later this year.

IRA FLATOW: Wow, Geoffrey, this is exciting stuff. Thank you for taking time to be with us today.

GEOFFREY ELLIS: Oh, you’re very welcome. I’m really happy to share it.

IRA FLATOW: Dr. Geoffrey Ellis, research geologist at the US Geological Survey.

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