The coming fusion revolution: My long-read Q&A with Arthur Turrell

By James Pethokoukis and Arthur Turrell

Recent headlines suggest fusion power is on its way, with researchers making breakthrough discoveries poised to revolutionize the energy industry. But will fusion be held back by the same fears and regulatory obstacles that hamper fission power today? And with the arrival of cheap solar and wind, do we even need fusion energy? In this episode of “Political Economy,” I’m joined by Arthur Turrell to discuss these questions and more.

Arthur is Deputy Director at the Data Science Campus of the Office for National Statistics in the UK and the author of The Star Builders: Nuclear Fusion and the Race to Power the Planet.

What follows is a lightly edited transcript of our conversation. You can download the episode here, and don’t forget to subscribe to my podcast on iTunes or Stitcher. Tell your friends, leave a review.

Pethokoukis: A skeptic might say — in fact, I’m guessing some skeptics have said in the past — that nuclear fusion is the future of energy and always will be. Yet over the past year, it seems to me — as someone who previously did not follow fusion and the developments very closely — that there’s been a lot of activity. These are just a few headlines from The New York Times: “Compact Nuclear Fusion Reactor Is ‘Very Likely to Work’ Studies Suggest.” And these two headlines are from over the past month or so: “Massachusetts Start-Up Hopes to Move a Step Closer to Commercial Fusion.” Another one: “Laser Fusion Experiment Unleashes an Energetic Burst of Optimism.” The New York Times has given fusion more coverage over the past year than is really typical over a number of years. So what’s going on?

Turrell: It’s a great question and it’s a really exciting question. I just want to remind listeners that I’m speaking in a personal capacity today, having recently written a book about nuclear fusion called The Star Builders. So I think that cliché joke, I think we can throw that away now. The reason I say that is because progress has always been dependent not on how long something takes, but on the level of investment and human ingenuity that is being put into something, and the investment and the human ingenuity that’s been put into fusion is starting to demonstrate some really interesting breakthroughs recently. The biggest of those — probably the biggest in the last five years — has been the emergence of a private sector in fusion, which suggests that there’s some market confidence. Investors must think that they’re able to get some return, whether from fusion energy or from technologies related to fusion.

So that is changing the game and it’s also increasing the pace of progress because, I think, it’s encouraging private and public alike to up their game. So that’s one thing that’s going on. The other thing is that some of those improvements and developments in public laboratories are starting to kind of emerge from the drawing board into practical application. So there have been a number of technological breakthroughs, things like superconductors, which allow for new types of experimental fusion reactor design, and there have just been some experimental breakthroughs as well. So for instance there’s been an enormous result at the National Ignition Facility — which is trying to do a type of fusion called laser fusion, based at Lawrence Livermore National Laboratory in California — recently, where they’ve demonstrated a world-record beating net energy gain from fusion. So the breakthroughs, the experimental results — not just in laser fusion, but actually in the other approach to fusion called magnetic confinement fusion, too — have really given the whole field a sense of optimism.

I would say it’s the most exciting time in fusion definitely for decades, but probably ever actually. Even though I’m saying a lot of things have happened recently, if I look at it in kind of a Moore’s law style, we are just carrying on the path that was established a long time ago. It’s just that that path is now taking us close to a point where the problem ceases to be, “Can we get more energy out than we put in?” And it starts to become, “How can we start to turn this into an energy source instead of a scientific experiment?”

My very basic understanding is, and please correct me, that there are two main approaches, both of which you mentioned: There’s the laser ignition approach and the magnetic confinement approach. Could you briefly explain what each of those is trying to do?

There’s actually a third one which you can see if you go outside right now, which is gravitational confinement, and that is how the sun does nuclear fusion. Of course we can’t do that on Earth, and it would be a very bad idea for us to try. For practical fusion on Earth, we need to find a way to contain material or fusion fuel that is at least tens of millions of degrees. 60 million degrees is the absolute minimum. That’s four times hotter than the core of the sun. So you can’t put this stuff in a container, because it would melt the container; it would dump its energy, and the fusion reactions would stop. So fusion is hard to start and easy to stop, which is one reason why it’s very safe as well. So you need something invisible that doesn’t touch the fusion fuel to confine it so that the energy stays inside and further reactions can go once they’ve been kicked off or ignited.

And the two main ways that people are trying to do this are magnetic confinement fusion and what is sometimes called laser fusion, but it actually belongs to a large group called inertial confinement fusion. Now, in the magnetic confinement fusion case, the stuff that you get in fusion fuel, the stuff that the sun is made out of, is the fourth state of matter. After solids, liquids, and gases, you get this stuff called plasma, and it’s made up of what you get when atoms get ripped apart (because there’s so much energy around) into their constituent parts of positively charged nuclei and negatively charged electrons. The thing about charged particles is they interact with magnetic fields, and in magnetic confinement fusion essentially what’s created is a magnetic trap of fields that these charged particles get stuck on, and so when they’re doing fusion, they stick around rather than flinging off away into the walls of the experiment, at least in principle.

Technicians at the Megajoule Laser project will be able to simulate nuclear tests using amplified energy from 176 lasers which is directed at a target located inside the sphere.
REUTERS/Regis Duvignau

Inertial confinement fusion takes a very different approach, and in fusion you’re always looking for temperature, density (so particles that are close together), and confinement. And if you reduce one of those, then you have to up the other two. What inertial confinement fusion says is, we won’t bother trying to confine it at all. We’re just going to bring together something at the perfect conditions for fusion, temperature and density, for a brief moment, and just let it rip. A brief moment is the time it takes a sound wave to cross the fuel once it’s been assembled, but a brief moment is a very long time in nuclear physics, and it’s long enough for a billion reactions to happen. In terms of bringing this fuel together at the right temperature and density for just that brief moment, you’ve got various different options and one of them is to use laser energy because you can squeeze a lot of energy into a small amount of space and a very short period of time with a pulse of light and create those conditions.

I think you used the phrase “net energy gain”so what does that tell you different from something called the “wall-plug energy ratio”?

Yeah, so I’m really glad you asked this question. It is so important to make this distinction. I think where most people start from is, they might see a headline saying nuclear fusion is close. We have to be really careful about what we mean by nuclear fusion, and the first thing that sometimes people mean is just doing some fusion reactions. But that’s easy and experiments can do it all the time. People have even done it in their backyards or in their garages, which I don’t recommend, but it’s possible. The next phase, and the thing that lots of scientists around the world — in fact there’s over 100 experimental fusion reactors operational or being constructed right now — are trying to do, is to demonstrate scientific net energy gain. And that’s about creating an experiment where you put in a certain amount of energy and you get at least as much energy back out.

And the reason why that’s such an important benchmark or milestone is because an energy source that you can’t get more energy out of than you put in is no good, obviously, and people are interested in fusion on Earth as a clean energy source. So scientific gain has been the next milestone for many decades now, but experiments are pretty close to that. But there are milestones beyond that, and the next one beyond that is something that you called wall-plug energy gain, and sometimes I call it the energy it takes to keep the lights on in the facility. So if you’ve got this experimental reactor, it’s the energy to charge up the capacitor banks, a type of battery. It’s the energy to keep the diagnostics running. It’s the energy to keep the lights on. It’s all of that peripheral machinery that you need to do a fusion experiment that isn’t just about the reactor, the experiment, the scientific bit itself, and that requires the gain, not of a hundred percent — so one unit of energy out for energy in — but a gain that’s appreciably more than that. It depends on the reactor, but I think what people would really like to achieve is at least 30 times energy out for energy in. Now, that sounds like a long way away.

Yeah, that does sound like a long way away.

Yeah. But you know, the nature of fusion is that it is a process that scales quite incredibly and to give you a sense of that, I’ll just say that in 2018 laser fusion on the National Ignition Facility, the record that they’d hit was 3 percent of net energy gain. That’s 3 percent where they’re trying to get to a hundred percent. But between 2018 and the latest results, which came out just last month in fact, they went from 3 percent to 70 percent. So they got a massive increase. It wasn’t going from 3 percent to 4 percent. It was going from 3 percent to 70 percent, and that’s because very small changes in initial conditions can produce very much bigger outcomes, and so when they’re making improvements, they’re getting factors of three or six or even 20 out in terms of energy gain. So when you think about it like that, they’re not actually very far away from a wall-plug gain potentially.

Is the private sector favoring one approach over the other? Again, we don’t know who’s going to “win,” but does there seem to be more innovation momentum on one particular approach or technology than the other?

That’s a really good question. I think it’s so early days that from a kind of societal point of view, it’s really great that people are exploring lots of different options, because we just don’t know which one is going to (a) work first, at least on the scale for a power plant or (b) which is the most commercially viable, which is incredibly important too. So it’s great that they’re pursuing different options. I’d say there are slightly more private sector fusion firms I’m aware of that are pursuing magnetic confinement fusion, but that technology has been around longer, and it’s been out in the open a lot longer as well. So more details of it are public as compared to inertial confinement fusion, but there are a non-zero number of private sector fusion firms pursuing the inertial approach, too, and in terms of the recent breakthrough at NIFT, that was an inertial fusion machine. But both are really promising, and I think it’s great that people are trying out every kind of option here.

Certainly one way to look at this is that government scientists have been working on this for a while and that didn’t work, so now the private sector has swooped in and they’re making great gains. But obviously, it’s really a case much like the private space industry in that the private sector is building on all kinds of research that’s gone before. Is technology at a state that there is a clean handoff to the private sector? Or are there still more basic research kinds of things that government needs to do?

I think that the quickest path to fusion is going to be a partnership between the public and private players. The public sector does some things really well and some things not so well, and the private sector does some things really well and some things not well. Part of fusion is this big laboratory scientific exploration, understanding the physics behind this state of matter, plasma, that’s incredibly badly behaved and not always that well understood, and really breaking through the frontier scientifically, and some of it is about: How do we do this on a scale that’s relevant for power generation repeatably, reliably, resiliently? How do we make it modular so that we can improve the learning rate with construction? How do we bring down the capital costs? And that’s the thing where the private sector can really contribute. I think the Department of Energy has recognized this with their milestone-based programs, where they’re making some of the public money available to private firms who can reach certain goals that are going to need to be reached to get to a future where fusion can actually deliver energy.

Model of an experimental nuclear fusion reactor in Cadarache, north of Marseille.
Via REUTERS

Has that basic science sort of been done and that’s understood, and now we’re moving on?

I wouldn’t say so. No. But I wouldn’t say that the science is just the preserve of the public laboratories, either. I think the private sector can get involved in that. Where I’d say we are, is that it’s pretty clear how to get scientific net energy gain now, but I think what we don’t understand is necessarily all the ins and outs of that. So we’ve got very close with 70 percent once, and magnetic confinement fusion came also quite close. That was actually back in the ‘90s. So we kind of got there a little bit, but I think we can understand how to really reliably do that on these big government machines, which have after all gotten closer than the private sector machines have to date. Where I think the public sector fusion efforts might go next is on working on some of the other big challenges of turning fusion into an energy source.

And that’s about being self-sufficient in the fuel for fusion, which involves some complicated physics on the material science of how we build reactor walls that can withstand this kind of energy release — which is not because necessarily it’s a lot of energy, although it is, but because it comes in a particular type in the form of high energy particles — and how we get the heat out of fusion reactions and ultimately do something that’s actually quite boring, which is use it to turn water into steam, to drive turbines, which we’ve done many times before. But that first step of getting heat energy out of the fusion reactor is something that people need to work on, too, and I think on all of those things the public or private sector could make progress, but right now there are public sector facilities around the world gearing up to try to tackle some of those challenges, particularly in the UK and Japan.

Why do we need star machines? If we need them for clean energy, isn’t that handled or will be handled by existing technologies? As you’ve written in the book, we’ve seen a big decline in solar costs and people seem very excited about renewables. So if it’s for climate change, aren’t these well-understood technologies the road forward rather than things like the star machines, which you just conceded still need a lot of research. If it’s not for that, then do we really need them at all for any other reason?

Yeah, that’s a really good question. Look, all of the star builders I spoke to — all of the engineers, physicists, mathematicians, computer scientists, entrepreneurs who are working on nuclear fusion energy that I spoke to — are absolutely convinced that renewables are going to be a key part of our energy supply. That’s a given, and they’re all convinced that climate change is a problem and that fossil fuels are on the way out. So I think everyone agrees on that. Why do we need fusion, then, if we’re going to get lots of energy from renewables? Well, I think they’re already going to be a big part of reaching that zero and beyond, absolutely. Renewables are already the cheapest form of power — except keeping existing nuclear fission plants open. But I think in almost anything that you do in life, it’s useful to have a portfolio of things with different strengths and weaknesses that you can draw upon.

So for instance, if I think about the advantages of renewables, they work right now and they’re very cheap, but on the disadvantages side, the energy that they tap into is very diffuse. It’s spread out over large areas, and that means that they need vast areas to work. So for example, to power the UK solely using onshore wind turbines would mean covering 17 percent of the country with turbines, which is a huge amount. It’s absolutely enormous, and as we’ve found this summer in the UK, the energy from renewables is not always reliable. So we’ve had a very un-windy summer in the UK here. Sadly, it hasn’t been that sunny either, but sometimes you want types of power that aren’t so reliant on the weather to provide that baseload energy.

Via Twenty20

Now, it’s true that batteries are going to play a large role in this as well and help us turn day into night when it comes to renewables. Some of the star builders I spoke to were skeptical about batteries ever scaling up to cover the whole year, but I think the other point here is that fusion could potentially provide energy at very large scales, too, and without using up lots of area. Even if we don’t get fusion energy until after net zero, we can start to suck down that carbon dioxide back out of the atmosphere and instead of just level off the curve of CO2 that we’ve submitted — start to actually reverse it and hopefully reverse some of the harms too.

So that’s one reason. Another reason in the long run why we might want fusion energy — and excuse me if this sounds rather futuristic — is that we are not going to explore the solar system as a species using a coal-fired spaceship. And in fact, if you look at what realistic trips outside of our kind of solar system’s backyard would have to be powered by — or even the Earth’s backyard, I should say — fusion is one of the best candidates for that because it packs a lot of energy into a very small amount of space. In fact, it’s 10 million times higher in energy density than coal.

So with a fusion-driven spacecraft, how does that change the calculus as far as traveling to the Moon, to Mars, the inner planets or the outer planets or beyond?

Great question. I don’t have figures at hand, but my understanding is that the time to get to Mars and back is cut substantially to something that is feasible. If you can use a fusion rocket instead of a conventional rocket, it’s all about the fact that you don’t have to carry as much fusion fuel with you because it contains a lot of energy.

When we talk about clean fusion energy, what is the scale we’re talking about? Will fusion reactors produce enough energy that we’ll need fewer fusion plants compared to coal plants?

So this is all of course assuming that fusion energy from power plants gets there and is commercially viable. So we have to bear that in mind, and there are big challenges on the way to that. But assuming that gets solved, then I think fusion energy would be broadly similar to what you can do with nuclear fission today — so in terms of land area, orders of magnitude more efficient than say, wind farms. We’re talking about a few square kilometers to power several million homes, which for a wind farm would probably take something equivalent to the land area of Washington DC for about three million homes.

So it’s much more space efficient. I think nuclear fission is great, and I’m really a fan of it as an energy source, but in terms of safety as well, nuclear fusion would likely offer an advantage, relative probably to all other forms of power. It would certainly be safer than some types of renewables and it would almost certainly be safer than nuclear fission as well — which, by the way, in the round is one of the most safe forms of energy.

Are both the safety issue as well as the nuclear waste issue the key advantages of fusion over fission, or are there other ones?

There’s another one as well, which is about nuclear proliferation. So if you are worried about rogue states using the materials involved in fission to construct nuclear weapons, those materials can be generated in relatively short time, or a peaceful fission program can be used as a cover for the production of the materials you need for nuclear weapons. The most extreme type of nuclear weapon is the hydrogen bomb, that makes use of both fission and fusion reactions, but the fusion reactions have to be triggered by fission reactions, and for that you need the fissile material. The great thing about nuclear fusion in this respect is that there’s no reason for it to involve any fissile material whatsoever. You only need the ingredients for fusion, which are kind of useless on their own for nuclear weapons.

A lot of environmentalists don’t like fission very muchmaybe that’s changing. Do they like fusion, especially since it doesn’t have that nuclear waste issue?

Yeah. So I think you’d have to ask some environmentalists. My sense is that the mood is changing a little bit on fission because there’s a trade off there. What do we think is the biggest problem here? Is it the really long-lived radioactive waste, of which there isn’t very much generated, or is it climate change? And right now climate change to me certainly seems like the bigger challenge that we face on planet Earth. But I think there are reasons why environmentalists would generally prefer fusion, and there’s obviously a reason why people sometimes talk about fusion as the holy grail of energy production even if all energy production forms have pros and cons. As you say, fusion doesn’t produce zero radioactive waste, but it doesn’t produce it as an output of the fusion reactions itself. The radioactive waste that we think will be produced is from the chamber being activated over the period of its lifetime. So rather than radioactive waste coming out all the time, what you end up with is what’s at the end of a plant’s life, when you need to decommission the reactor chamber. And the best guesses suggest that that will be dangerous for a much shorter period of time — on the order of a hundred years as compared to the waste that’s produced as a part of ongoing processes in fission, which although small in volume, is dangerous for a lot, lot longer than that.

Containers are seen at a plant for processing liquid radioactive waste at the Chernobyl nuclear power plant in Ukraine. REUTERS/Gleb Garanich

I’ve talked to a lot of entrepreneurs about different technologies they’re working on, such as autonomous cars. You talk to those guys and you walk out of that and you think, “This thing is going to happen. It’s going to happen soon.” It’s very exciting. I’m sure you felt that excitement, and you have to sort of temper yourself. Now that you’ve written this book and you’ve had a chance to breathe a little bit, what is the reasonably optimistic take on when I’m going to be able to flip on a light switch and that’s going to be fusion-supplied electricity to my light bulb?

So let’s start with the big picture here. Fusion is the most ubiquitous energy source in the universe. It powers stars, it was around in the Big Bang, it’s around in supernovae. It’s kind of embarrassing that we haven’t managed to do it on Earth in a way. So I think humanity will get there. It’s the most energy-rich source of fuel that we can lay our hands on, reasonably, in the solar system or in the known universe. So I think we’ll want to do it at some point for those reasons I said about exploring the universe as well. I’m really optimistic that we’re going to do this at some point. There are extra reasons to do it in the short run, and I completely hear what you’re saying about people being over-optimistic, and, in fact, fusion has been terribly guilty of that in its history. People working on fusion have said, “Oh, it’s about to work. We’re going to deliver fusion energy.” And they haven’t really defined what they mean by that (which is why I was really keen to get that in earlier), and it’s incredibly difficult. You know, fusion is probably the greatest scientific and technical challenge that we as a species have ever taken on. So it’s very difficult to do at the small scales that we want to do it here on Earth compared to how it works in the sun, but just because a feat is difficult to achieve doesn’t mean we should rule it out. I think you can never underestimate what human ingenuity can achieve, and it might seem wild and fanciful to get this thing that powers stars and happens in supernovae working on Earth, but if you look at human history, so many wild ideas have unexpectedly come to fruition.

And I take a recent example here, which is Katalin Karikó’s research on mRNA to fight diseases, which seemed such a long shot that she couldn’t even get it funded. She got demoted, but we’re really lucky today, where we sit here in 2021, that her and her collaborators persevered because some of the most successful COVID vaccines — and a vaccine for malaria as well — are based on that technology, and the vaccines were developed in record time. And that’s partly about people dreaming big and persevering, but it’s partly, and this comes to a more practical point, that society said, “Yes, we are going to put our weight behind this. We’re going to invest a lot in it and we’re just going to make it happen.” And that’s what made the difference from this being a technology in principle to a technology in practice that is out there saving lives every day. So I think whether we’re going to see fusion energy really depends on if we, as a society, decide to pursue it and whether we give it the investment we want, but there’s lots of evidence from the rest of the universe and from the experiments that have been done that we could get there if we wanted to.

If you could just name a few of the private sector companies that you’ve talked to, whose work you’ve reviewed, to just give a sense of like who’s out there doing what.

Yeah. So on the inertial confinement fusion side, there’s a firm called First Light Fusion who are interesting. Instead of using lasers, they’re using projectiles to ignite those fusion reactions. There’s another firm who I went to speak to and visit called Tokamak Energy. So they are using a type of technology called a spherical tokamak. These tokamaks are basically these magnetic traps I mentioned, but the point about making it spherical is you can make it more compact and that has some real benefits from a commercial point of view and making things more modular.

The Experimental Advanced Superconducting Tokamak fusion device, nicknamed “artificial sun”, is tested at the Institute of Plasma Physics. REUTERS/Jianan Yu

Over in the US, one of the firms that I think is really interesting to watch is Commonwealth Fusion Systems because they’ve been born out of a really well respected set of researchers and a fusion program at MIT. They’re also using some more compact superconducting tokamak-type technologies. There are a bunch of others around, some are more plausible than others, but because they’re private sector firms, we don’t know all of the details of them. So it can sometimes be hard to compare and get a good sense of who’s ahead with the technologies.

My guest today has been Arthur Turrell, author of The Star Builders: Nuclear Fusion and The Race to Power The Planet. Arthur, thanks a lot for coming on the podcast.

Thanks for having me, Jim.

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