Dylan Matthews (5:53)

It's really tantalizing that we are sitting on this big mass of hot rocks just a few miles beneath us, and it's so hot that in theory, it's more energy than we could ever need if we could maybe get at it.

Noam Hassenfeld (6:06)

That's Dylan Matthews. He's a senior correspondent on Vox's Future Perfect Team. And he writes about all kinds of big world changing ideas, from global health to economics to energy. So I asked him just how Possible all of this is. So if you aren't lucky enough to have that hot water kind of bubble all the way up like it does in Iceland, what do you do to get at it?

Dylan Matthews (6:31)

So up to now, the answer's been that unless you're on geysers or volcanoes or things, you don't. But there are efforts to make geothermal viable outside those areas. And the basic idea, which takes a bunch of forms, but all of them share the idea that you drill down really, really deep and you pour some kind of liquid down there and you get steam or hot water coming up, and then you can either use the hot water directly or you can use it to spin a turbine and make electricity.

Noam Hassenfeld (6:58)

Okay.

Dylan Matthews (6:58)

There's a few different companies trying this, but they're all variations on the same idea of like dig or blast really, really deep, pour some liquid in there, use that to spin a turbine, or get some hot water.

Noam Hassenfeld (7:10)

I mean, that seems like relatively straightforward to me.

Dylan Matthews (7:13)

It is a lot harder than it seems. The biggest barrier that I've heard from people is just that getting that deep into the earth is really tough. It's really expensive, but. And there's also been a concern about what happens when you pour liquid into rocks that deep. There was a demonstration project in South Korea that wound up causing a magnitude 5.5 earthquake. Whoa.

Noel King (7:38)

Residents of the city of Pohang had.

Dylan Matthews (7:40)

To evacuate as aftershocks from Korea's second.

Noel King (7:43)

Largest earthquake on record destroyed thousands of.

Dylan Matthews (7:45)

Homes and injured dozens of people.

Noam Hassenfeld (7:47)

Investigators confirmed it was man made, caused by a nearby geothermal power plant.

Dylan Matthews (7:57)

I feel obliged to say that this was an unusual incident in most geothermals today. It has not been associated with any significant seismic activity. But this was a concern people had about fracking that has, I think, held up to some degree.

Noam Hassenfeld (8:10)

Yeah, I mean, you're. You're kind of like weakening the. The ground, right?

Dylan Matthews (8:14)

You're weakening the ground. You're messing with the system deep in the earth and you're putting liquid potentially in places where it hasn't been before.

Noam Hassenfeld (8:22)

Yeah.

Dylan Matthews (8:23)

This is part of the reason why some companies are building what they call close loop system. So instead of just pumping liquid into the ground and it heating up, you actually place a pipe all the way into the ground. And that way you're not leaking the liquid permanently. But that's really hard. You're actually like placing in piping potentially thousands of meters under the earth. And so it's more investment in a very difficult kind of drilling. And we don't have really good drill bits. It sounds like such a trivial or technical thing. But when I talk to people about geothermal, one of the things they bring up again and again is just like, we don't have good drill bits.

Noam Hassenfeld (9:04)

That is crazy that the thing that is standing, or at least one thing that is standing between us and kind of limitless, clean, constant energy is drill bits.

Dylan Matthews (9:12)

It seems really dumb, but also, I don't know, rocks are really hard. It makes sense that that can be a real technical limitation. The more you learn about industries like this, it all becomes incredibly complex to do something seemingly simple in the most closed loop systems that people are trying to build right now. It is still at a point where you could generate electricity, but it won't do so super efficiently. So even if you nail all this, it might be hard for it to be cost competitive with something like solar or wind.

Noam Hassenfeld (9:44)

So then why do it at all?

Dylan Matthews (9:46)

So right now it's inefficient and we can't make that much energy from it relative to the cost. But the ultimate dream is that you can get 4km or even deeper into the ground. And this is where we get into what is super technically known as super hot rock energy.

Noam Hassenfeld (10:03)

Oh, all right.

Dylan Matthews (10:06)

We've so far been talking about hot rocks. Now we're going to talk about super hot rocks.

Noam Hassenfeld (10:10)

Hot and hard rocks.

Dylan Matthews (10:11)

Hot, hard rocks. Super hot, super hot, super hard rocks. And at that point the rocks are going to be over 752 degrees Fahrenheit. And a special thing happens then, which is that water H2O becomes supercritical, which is a phenomenon where it acts both like a liquid and a gas. The pressure sort of liquefies it. The heat like is pushing it toward being a gas. It's stuck in this sort of mysterious in between state, but that means it can hold a lot more energy. The heat in the water is easier for turbines to turn into electricity. And you can get more electricity from the heat you're taking out of the earth than if you were sort of digging a little shallower and not getting to the supercritical level.

Noam Hassenfeld (10:55)

Okay.

Dylan Matthews (10:56)

The hard part is getting 4 km into the earth. Yeah. And so once you start asking that question, you start to hear ideas like this one company wants to fire what are called millimeter waves into the ground. Vaporize the rock.

Noam Hassenfeld (11:10)

Vaporize the rock.

Dylan Matthews (11:11)

Just like fully vaporize it. Things get more and more sci fi sounding in this. And the best part about this is you could just hook into our pre existing power grid. So we've got all these coal plants, they're already Hooked up to the grid, they already have the transmission you need. And you could just replace the sort of coal burning that goes into the turbines with geothermal. So once you get this to work, it's kind of plug and play. It's a pretty easy transition. But the sort of once we get this to work is a huge caveat.

Noam Hassenfeld (11:44)

So given what we know we need to do here and even the vision that we have of it working efficiently someday.

Dylan Matthews (11:50)

Right.

Noam Hassenfeld (11:51)

Why isn't this happening? Is it the drill bits?

Dylan Matthews (11:55)

I mean, there's. Yeah, there's a lot of ways to look at the causes. Some degree it's about the drill bits, but why don't we have better drill bits? We've gotten better mining technology and other things. We've gotten better solar. Why haven't we invested in this? And I think some of that is that we need a lot for this to go. Right. You need a lot of technical innovations, especially if you want super hot rocks. And often when we're trying to develop early stage technologies like this, you need a lot of government help and subsidy. It requires a ton of, of just like physical investment up front.

Noam Hassenfeld (12:25)

Yeah, they're like these huge complexes.

Dylan Matthews (12:27)

Right. And we're at a time when administrations differ really profoundly on energy issues. Politics is really unpredictable with Trump. It's not always clear what he feels about stuff day to day.

Noam Hassenfeld (12:38)

Right.

Dylan Matthews (12:39)

So if you're one of these projects that's like a multi year, hundreds of millions of dollars physical infrastructure project, one thing you want is consistency. You just like want to know that the support you're relying on from the government is always going to be there. And one thing our government has not been recently is consistent. All that said, the geothermal people I talk to are kind of optimistic, cautiously optimistic at this point for some maybe surprising reasons.

Noel King (13:18)

Dylan Matthews, he's a reporter on vox's Future Perfect Team. Coming up, Noam Hassenfeld returns from Iceland to tell us where all this optimism is coming from.

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Noam Hassenfeld (13:53)

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Noel King (14:55)

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Noam Hassenfeld (16:00)

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Noel King (17:07)

I'm Noel King. Today Explained is airing an episode from our friends at Unexplainable.

Noam Hassenfeld (17:12)

Here's Noam simple, hot, simple. This year, geothermal has been everywhere that geothermal so hot right now in the first few months of 2025, there's been almost as much geothermal investment as there was all of last. And there's also been a lot of progress on the ground or under the ground. One company in Utah has drilled 15,000ft down to a point where the temperature is over 500 degrees Fahrenheit. So almost to that supercritical stage. There's a company that does closed loop geothermal. So the kind where the water is always in an underground pipe and it doesn't leak, they're on track to generate actual electricity. This year, the rock vaporization guys just made their first real world demonstration. And then, even though Trump's big old bill made huge cuts to wind and solar investment, there was a specific carve out for geothermal, in large part due to the current Energy secretary, Chris Wright.

Dylan Matthews (18:19)

Will you pick up the phone and push congressional Republicans to maintain the energy.

Noam Hassenfeld (18:24)

Tax credits for geothermal? I have been doing just that. Wright has founded multiple fracking companies and he's been a big investor and backer of geothermal for years. It's just an enormous, abundant energy resource below everyone's feet. Geothermal energy crosses partisan lines. It's renewable energy just for people that like oil and gas, because it's all about drilling. And fracking is a big reason geothermal has even gotten this far.

Dylan Matthews (18:56)

The fracking revolution has dramatically improved the technology for drilling deep into the earth. And it's been a big boon to geothermal, sort of accidentally, that natural gas has invested many, many billions of dollars into getting better at drilling deep. And so you have this very skilled workforce and these new drilling technologies that can make it easier than it would have been 15 years ago before fracking had made all this progress.

Noam Hassenfeld (19:26)

That's interesting.

Dylan Matthews (19:27)

Yeah, this is something you hear a lot from geothermal people of. What does a just transition away from a fossil fuel economy look like? And one of the questions they want to ask is, you know, what happens to the people who are doing all the drilling, who are producing all this oil and gas right now? And one potential answer is, well, they keep drilling, but they drill geothermal wells rather than oil and gas wells.

Noam Hassenfeld (19:48)

This all sounds great. It sounds even, you know, dreamily bipartisan, but we do Know, there are downsides. There's the earthquake you mentioned. Even if it's maybe a rare event, if this is kind of relying on a lot of fracking technology, is there a possibility that this is going to lead to a lot of the problems that fracking led to?

Dylan Matthews (20:07)

I mean, I think there is. Anytime you're drilling into the earth, there are risks, especially regarding sort of the liquid you're using, potential contamination of groundwater. And I think there have been fracking projects in the US that have had fairly minimal impacts in that regard. There are ones that have had very bad impacts. And so I would hope that if we're doing this with geothermal, we would try to emulate best practices and avoid that. But at the end of the day, geothermal and natural gas are very different technologies. One of the big concerns with natural gas is that methane leaks from either drilling site or from pipelines, and that just doesn't happen to any significant degree with geothermal.

Noam Hassenfeld (20:44)

Yeah, we're not trying to get at methane in the ground here.

Dylan Matthews (20:47)

Right, right. Natural gas, like, sort of is methane. Yeah. Yeah. That's strange rebranding. Yeah. It's a fairly specific problem to them. And I think with any new technology like this, the thing that everyone developing is afraid of is that people will get spooked about it the way people got spooked about nuclear, and will shut it down before it has a chance to prove itself. And so I would say that the attitude is one of an abundance of caution.

Noam Hassenfeld (21:11)

So if this does work, you know, and we do end up doing it safely and responsibly, it feels like this has the potential to really stick.

Dylan Matthews (21:20)

Yeah, I think that's the dream. The asterisk is always like, it needs to work.

Noam Hassenfeld (21:26)

Right.

Dylan Matthews (21:27)

The thing about fracking is that it provided all these jobs for people in drilling, but it also provided a really cheap and reliable source of energy. It worked, and it was cost competitive. And the challenge for geothermal is, okay, you have this attention, you have government regulators that are paying attention, you have the Trump administration that is pretty positive on all kinds of drilling, both oil and gas and geothermal. So now can you do it right? And I don't know. I think the nuclear industry has had a lot of, like, innovation and big ideas in the last 15 years, and it's just kept getting more expensive. And ultimately the. The proof is in the.

Noam Hassenfeld (22:08)

The drilling.

Dylan Matthews (22:08)

The proof. The proof is in the drilling. I was going to say something about the levelized cost of energy, but the proof is in the drilling is pithier.

Noam Hassenfeld (22:18)

I'm curious if you can just paint me a picture of what the world might look like if we do get this right. Like what would a world with fully tapped geothermal potential look like?

Dylan Matthews (22:30)

Yeah. There was a report from these two energy experts I like a lot, Austin Vernon and Eli Dorado, that was trying to like really give a kind of blue sky, almost sci fi picture of what you could do if you just like didn't need to worry about scarcity of energy. And I think part of the point of the exercise is to sort of highlight ways in which not having enough energy for stuff kind of structures our world even as we don't realize it. Like vertical farming. People have been trying to do farming in a way that makes better use of land and takes up less of our landscape. The real problem is that you need tons of energy for it. If you had abundant geothermal, you could have skyscraper farms, you could have desalination plants that sort of obviate the need for these huge aqueduct systems in places like California. You would have more than enough energy to get all the drinking water you need from the ocean. I think the point of this is not like draw some sci fi utopia, but just a lot of our world is structured by what we don't have. And we definitely don't have enough energy to do all the things that we want to do. And an appealing thing about geothermal is that there's way more heat in the earth's crust than humans would ever know how to use in a million years. And that can be pretty exciting.

Noam Hassenfeld (23:52)

So then to get to our sci fi energy abundant future, we just need to have consistent politics that we all agree on. Massive government spending and really, really good drill bits.

Dylan Matthews (24:07)

Yeah, but other than that. Yeah, very easy.

Noam Hassenfeld (24:11)

So what do you think ends up happening here? How optimistic are you in the end?

Dylan Matthews (24:17)

So I want to sort of distinguish kinds of optimism here. Do I think there will be one company or two that is doing geothermal, the kind that you can do almost anywhere and doing that at a reasonable scale? I say I'm pretty optimistic. I think that's more likely than not. There's a difference though between that and this is a major source of energy in the US And I'm a lot less certain on this will get to a point fast enough that it is, it can sort of win the race with wind and solar and batteries and that kind of thing.

Noam Hassenfeld (24:50)

And it's just a matter of what works fastest, best and cheapest in the end.

Dylan Matthews (24:55)

Yeah. For better or worse, the US energy system is run by rapaciously bottom line oriented capitalists. And so if the cheapest way to provide electricity in Texas, the state that produces more oil than any other state, is to use solar, they'll use solar. And sure enough, they build a lot more solar than states that you would think of as more pro solar. And I think that's been driving a lot of progress toward renewables lately. And that can be pretty ruthless for young technologies. So I don't want to I think there's still totally a world where this is a cool idea that gets some adoption but does not take the world by storm. But there's also a world where it works better than we thought it would and it kind of surprises everybody. And yeah, in that world, maybe you come back and you re listen to this and think, yeah, maybe those guys were onto something.

Noam Hassenfeld (25:45)

All right, Dylan, thanks so much for coming on the show.

Dylan Matthews (25:48)

Thanks for having me.

Noam Hassenfeld (26:00)

This episode was produced by me, Noam Hassenfeld. We had editing from Jorge Just mixing and sound design from Christian Ayala, music from me, production support from Thomas Lu, and fact checking from Melissa Hirsch. Meredith Hodinot runs the show, Julia Longoria is our editorial director and Bird Pinkerton stared at the platypus who looked down and sighed. They have the babies, the puggles. The birds said if we didn't help them. Thanks as always to Brian Resnik for co creating the show. And if you have any thoughts about the show, any criticisms, show ideas, personal reflections on anything you've heard, send us an email. We're@ unexplainableox.com we love hearing from you and we read every email.

Noel King (26:51)

They do read every email today explained. We'll be back tomorrow with an episode about affirmative action. The Supreme Court ended race conscious admissions two years ago. About two years ago. But the Trump administration thinks elite colleges are cheating and it's trying to catch them in the act.

Noam Hassenfeld (27:19)

Sa.