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Steven Cowley

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Steven Cowley has been a guest on Cleaning Up: Leadership in an Age of Climate Change .

Recently: “Is Nuclear Fusion About To Have A Theranos Moment? Ep 277: Sir Steven Cowley” on Cleaning Up: Leadership in an Age of Climate Change (October 2026).

What They Said

“What I worry about is we'll have sort of fusion's Theranos moment … where investors say you didn't exaggerate, you actually duped us, right? And if that happens, it'll cool the whole market.” — Steven Cowley, Cleaning Up: Leadership in an Age of Climate Change

The host asks whether the wave of private money into fusion could end in a backlash that hurts the public research programs too. Cowley says finance is not his area but that he very much worries. He adds that there are about 60 fusion companies with different ideas, that he knows nobody fraudulent, but does know people he thinks are "over-egging what they have".

Cleaning Up: Leadership in an Age of Climate Change · 2026-10-07 Permalink → Listen →
Cleaning Up: Leadership in an Age of Climate Change Around 48:25 into the episode
Steven Cowley

I tell you one of the things that does frustrate me with the private fusion industry. We have developed computer models of plasmas in the last 15 years that are very close to what we measure, right? We're often measuring exactly what we calculated in the computer. And so guessing what's going to happen as you get towards fusion is not the right strategy. You need to calculate. And we can help a lot of the companies. We're helping 15 fusion companies by doing simulations basically for them of their things. We're not doing full simulations, although we're doing some work for those field reverse configurations.

Speaker 3

And does the moment we're in with private money coming in, does it concern you? Because there's nothing I've heard that's convinced me that we're good. You know, you've got the, you started by saying that the US government's target is 2035 to 2040. And I tried to push you to say whether you thought 2028 was realistic. And I'm going to read between the lines. And so, you know, you don't seem over. convinced. Are you worried that this sort of moment of excitement just leads to, you know, just ends up dissipating and you couldn't really call it a bubble and a bust because it hasn't involved the, I was going to say it hasn't involved the stock market, but of course you've got TriAlpha TEA, which is now, has now become part of a quoted entity, as has, I think, General Fusion, which is a Canadian-based, you know, we're going to make a ball and then collapse a ball using pistons and explosives and all sorts of things. Also quoted now. Are you worried that there'll be a pushback, that people will end up in a few years saying, ah, that didn't work and it was all nonsense and that that would affect the programs that you work on?

Steven Cowley

I very much worry. This is not my era of expertise, finance, but what I worry about is we'll have sort of fusions Theranos Moment? Ep there are some really good companies. So Fusions Theranos Moment?. Theranos moment. Right. Where investors say you didn't exaggerate, you actually duped us, right? And if that happens, it'll cool the whole market. And there are a lot of really good companies, right? But there are 60 fusion companies, all with different ideas, right? They can't be 60 ideas that are all, you know, and certainly some of them strike me as I don't know anybody who's fraudulent, right? But I do know people who I think, you know, are over-egging what they have.

Speaker 3

When we started, I want to finish by talking about the costs and the economics of this, because doing it is one thing, but doing it at a cost point where it can compete into the energy system. And there's this marvelous phrase, which I'm afraid you've used a few times in other conversations, baseload. And baseload is regarded by many as the sort of the holy grail, you have baseload. But baseload, if you have an electricity source that produces 24-7, 365 power, in a world which is dominated by intermittent power, it's actually not fulfilling a very useful function in the energy system. Because every time it's windy or sunny, or you've got very cheap batteries as well, every time there's electricity available at a very, very low marginal cost, your much more expensive to run equipment is going to be shut down.

Steven Cowley

Well, you're making the assumption it's much more expensive, but it, you know, probably at least initially will be. Fusion can be switched on and switched off. There's no question that you could do that. But there's a cycle. This is true also. One can make nuclear power stations that you switch on and switch off. You just don't want to do it because the marginal cost of keeping running is not very much, right? Whereas because your fuel costs are so low, right? And your running costs are so low. You've got to keep the reactor there. So it is true that when you have a technology that's dominated by its investment cost and not its operational costs, you want to keep it running all the time.

Speaker 3

Correct. But the problem here is that the running cost of a solar farm is almost exactly zero. I mean, it's really in wind, you've got some maintenance. So what we've got even in nuclear now, just running and maintaining a fission power station is $30, $40, $50 per megawatt hour. And so they're being competed out by wind and solar and batteries because the marginal cost is almost exactly zero. So it's a problem. And the reason you don't want to cycle, apart from the fact that you get temperature cycling and cracks and all sorts of bad things, the moment you power it down, it's not earning any money. And so the cost of the rest of the power goes up. So I guess I worry that you could do all of this. And in the end, other than the first few that are heavily subsidized, that it may never find its role in life in the energy system.

Speaker names from our own diarization · position estimated from where the line sits in the episode
“If you have to make targets with gold hohlraum, they have to cost roughly 20 cents each. At the moment, they cost $10 million each. So we're a little ways off, right?” — Steven Cowley, Cleaning Up: Leadership in an Age of Climate Change

Cowley is explaining the "indirect drive" approach to laser fusion used at the National Ignition Facility, where lasers hit a small gold container, the hohlraum, to make X-rays that collapse a peppercorn-sized fuel target. It makes the implosion more symmetrical but is inefficient. He says most laser fusion companies are instead trying to shine lasers directly on the pellet, which has not yet been made to work.

Cleaning Up: Leadership in an Age of Climate Change · 2026-10-07 Permalink → Listen →
Cleaning Up: Leadership in an Age of Climate Change Around 28:57 into the episode
Steven Cowley

that's such a carefully worded question michael indeed um focused energy has some very smart people in it um they're doing some very interesting things this is early stage deep tech right this is that you know that there is a there's a lot of risk being taken um but there's a lot of reward at the end of the line right it's it is quite possible that at some point fusion will be 30 of the energy market that's a heck of a lot of money right and so you know a certain amount of risk taken to accelerate development of that i think all the fusion companies are doing that so i pay attention to pretty much all the fusion companies there are a few that are just plain bonkers right and that's a technical term um and um and and you know there's bound to be in this space but there's been 15 billion in in investment in fusion companies in the last six or so years uh that's a heck of a lot of investment compared to the public sector program and so you know we've got to get something out of this out of this process to accelerate fusion so i'm paying a lot of attention

Michael Liebreich

I could also rephrase my carefully phrased question, which of course was trying to trap you into saying things you might later regret. But if I rephrase it and say, is laser containment a worthy competitor to magnetic containment? Is it obvious that one's ahead, one's behind, that one's challenges are... We're going to come on to talk about magnetic, but do you think they have a chance of beating the magnetic containment route, which is the one that mainly you and your colleagues work on?

Steven Cowley

I have preferences, but we're at a very early stage of the technology and things overtake, right? And the NIF results certainly said that, yes, you know, inertial fusion is coming along very fast. But most of the laser fusion companies are aiming to do it differently than NIF. And in particular, most of them do what's called direct drive. So indirect drive is what they do at NIF. You have this little gold container, the holrum, and the lasers shine in end holes in the holrum, and they make x-rays from the gold. And those x-rays then collapse the peppercorn-sized target in the middle. That's easier because the x-rays make it more symmetrical and the push is more symmetrical, which you've got to have, right? But it's terribly inefficient because you convert laser energy into x-ray energy and then the x-ray energy does the implosion, et cetera. And that gold holrum, if you have to make targets with gold holrum, they have to cost roughly 20 cents each. At the moment, they cost $10 million each. So we're a little ways off, right? So it'd be much easier if you just made the peppercorn thing in the middle, right? And so people at University of Rochester and I think Focus Fusion are aiming to shine the lasers directly on the pellet. Now, we've never made that work, but it in principle does work.

Michael Liebreich

Okay, so thank you. I'm trying to get the right level between kind of, because it is the physics that tells you, it's the X-rays and the physics that tell you whether the thing is to be gold or whether you can get rid of the gold. So we are in the right zone, I think. I hope people are able to follow this. Because I think the short version is that, yes, it is a worthy pathway and big challenges, but a worthy pathway and some very good science being done. Some of it funded by private companies and good luck to them. But it sounds like there's a lot of science still needing to be done. Cleaning up is proud to be supported by its leadership circle. The members are Actis, Alcazar Energy, ARIP, Climate Imperative Foundation, Copenhagen Infrastructure Partners, Signum Capital, Davidson Kempner, Eco Pragma Capital, EDP, Euroelectric, KKR, Mitsubishi Heavy Industries, National Grid, Octopus Energy, Quadrature Climate Foundation, Schneider Electric, SDCL, and Vartzilla. For more information on the leadership circle, please visit cleaningup.live. To keep up with all that's going on in the cleaning up universe, make sure you subscribe to our newsletter. Written and edited by my longtime New Energy Finance and Bloomberg NEF colleague, Angus McCrone. It comes out every second Monday. Angus provides the latest on the episodes we're recording, the events we're hosting, stories we're watching, and what Bryony Worthington and I are up to. To sign up for the Cleaning Up newsletter, visit cleaningup.live. Let's move on to magnetic containment. So, because then we get to talk about plasma, your favorite, your favorite subject. I'm assuming, given that you run the plasma physics lab, that it's a favorite subject. These are the big circular structures, the tokamaks, all these things called stellarators. And a stellarator means a star maker. Broadly, it's stuff that's going round and round. And it's contained by big magnets. What are you trying to do with that?

Speaker 3

And why is it hard? Let's start with the real basics.

Steven Cowley

You know, fusion doesn't happen until you get sort of above about 100 million degrees. I mean, it happens, but it's so low level that you wouldn't worry. But you've got to get to 100, 200 million degrees. And then you've got to hold your fusion, your deuterium and your tritium, which are your fuels, while they come together, they bombard each other most of the time, about 999 times out of 1,000. When deuterium hits a tritium, it just bounces off, right? That one part in a thousand. it fuses, you've got to get it hot enough that it can get close enough that it can fuse, right? So you've got to hold something at 200 million degrees. And the magnetic fusion is to hold it steadily in a cage of magnetic field at 200 million degrees and give it time to fuse and do it continuously. Not an explosion, but just continuous output of fusion power from that. And that, as I say, on jet, we actually did that, right? We held it there. Five seconds doesn't sound like a long time, but it's well past any of the other times that you worry about. We held it steady. It produced 12 megawatts of power for five seconds. Excellent, right? So the cage kind of works, but at this point, so the problem is you also want the fusion to heat the fuel because you want to put more fuel on and you want it to heat it, but like a burning fire. If you have a burning fire and you add another log, you don't want it to go out. You want to ignite the log and then put another log on and then put another log on. So we want it to heat itself as it's doing fusion. And it will do that. But to do that, you've got to get it self-heating to beat the leakage of heat. Otherwise, it will just get colder and colder and colder and it's stopped doing fusion, right? And to do that, we have to make very large magnetic bottles because in the middle, it's bubbling away. This plasma is actually turbulent and it's bubbling away and the heat is leaking out of your device. Now there are two ways to make the leakage. Actually, there's really three ways to make the leakage less.

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