Skeptics joke that nuclear fusion is the energy source of the future … and always will be. But when the Biden White House made a big announcement about the progress of fusion research last week, even diehard skeptics surely took note. My guest on this episode of Faster, Please! — The Podcast is Arthur Turrell, plasma physicist and author of 2021's excellent and must-read The Star Builders: Nuclear Fusion and the Race to Power the Planet.
In This Episode
The consequences of fusion’s latest breakthrough (1:06)
Where does fusion go from here? (3:55)
The best path forward for fusion (8:14)
The importance of fusion for an energy-abundant future (13:13)
Will star power take us to the stars? (24:09)
Below is an edited transcript of our conversation.
The consequences of fusion’s latest breakthrough
James Pethokoukis: On December 14, Energy Secretary Jennifer Granholm announced that researchers at Lawrence Livermore had succeeded in generating a net-energy-gain fusion reaction. Just how consequential is this?
Arthur Turrell: Jim, I would say that we're witnessing a moment of history, really. Controlling the power source of stars, I think, is the greatest technological challenge humanity has ever undertaken. If you look back at human history, there are different stages where we've unlocked different types of energy sources. You can think about unlocking wood. You can think about when humans started to use coal, which packs in more energy than wood. You can think about nuclear fission, which has even more energy than coal. A lot more, because it's a nuclear technology instead of a chemical one. And then you can think about this moment when we have the first proof of concept of using fusion for energy. And of course, fusion unlocks huge amounts of energy: 10 million times, kilogram for kilogram, as compared to coal.
There are two main approaches to fusion as I understand it. This was what they call inertial confinement, and then there's magnetic confinement. Does it make a difference, as far as where this technology goes, that it was inertial confinement versus magnetic?
It's absolutely a huge scientific achievement. The level of precision and the level of innovation and invention that the researchers at Lawrence Livermore have had to deploy to get here is just an astonishing feat on its own, even if we weren't talking about how this could eventually change the supply of energy.
Does it get us anywhere? I think the honest answer is we don't know. We, today, don't know what version of fusion, what way of doing fusion is going to ultimately be the one that is the most economical and the most useful for society. But what I think this result will do is have a huge psychological effect because throughout fusion's history, researchers have said, “Hey, I'd really like to, you know, build a reactor, a prototype reactor.” And funders have quite reasonably said, “We don't even know if the principle works. Go off and show us that it can produce, in principle, more energy out than is put in.” And of course, fusion research has been trying to do that since the 1950s. Now we finally and absolutely have proof of that. I think that it's going to crowd in innovation, interest, and investment in all types of fusion because even though this approach got to that milestone first, it doesn't necessarily mean that this is going be the most economical or the best in the long run.
Where does fusion go from here?
I think it's Benjamin Franklin who gets the credit, at least that's what I learned in third grade, for discovering electricity in the 1700s. We didn't get the first electric motor until the 1820s, and we really didn't get factories electrifying their factory floors really until the first decades of the 20th century. So this could be an amazing discovery, but it could be a long time just based on how fast it takes advances to be modified and diffuse into an economy. It could be quite some time, if ever, before this actually gets plugged into a grid.
Right. Traditionally, these new energy sources take a long time to come onstream. One of my favorite facts, and I have to double check that I've got the year right here, but I think the first solar cell was working in 1883. And only now in the last few years has solar energy become commercially viable in terms of cost. These things take a long time, or they have historically. And here's the really important point. It's never about the amount of time. It's about the amount of investment and political will that we put behind it.
If our elected representatives choose to really push this and put lots of funding behind it, and the private sector decides that it's really going to push this, things will move much faster. Correspondingly, if we don't put lots of investment behind it, things will move more slowly. But you are absolutely right when you say that there is a gap here between what we've seen — which is an astonishing experiment, but only scientific feasibility — and what you'd have to have for fusion energy to be on the grid — which is solving some of the engineering and economics challenges that stand in the way between this one-off experiment and doing this repeatedly and economically at scale.
For decades, there was very little in the news about fusion research. And since 2019, there have been some big stories about the advances happening in government labs and about the work in the private sector. It seemed like there was already a lot of excitement before this advancement. I can't believe this won't generate even more interest.
Absolutely. I think this has been building for quite a long time. It's very tempting to say not much has happened in fusion. But I think if you look back over the decades, there have been improvements. They've been quite steady, and they've probably been coming at the rate you would expect with the level of investment and dedicated resources it's had. But the improvements have been arriving quite steadily. And looking at the history of this particular experiment, the National Ignition Facility, when they've got improvements since 2012 when they really started this type of campaign, the improvements have resulted in a five- or six-times increase in the release of energy. Back in 2019 when the book I wrote about this came out, I sort of said, “Well, they're not actually that many improvements away, so if they can carry on the same trajectory, they're going to crack it at some point.” And last August in 2021, they got to 70 percent, which at the time was a world record as well. And it’s kind of like, because fusion scales nonlinearly, especially in this type of doing fusion, this laser fusion, actually they're almost there and it's just a matter of time until they crack it. So I think it's been building for a while. And the huge successes, because things have just happened to have gotten close now after all of this time in both magnetic confinement fusion and in inertial or laser-based fusion, mean that has really stimulated the private sector as well. The whole thing is starting to build on its momentum. And I think that now this is going to cause the wave to crash over and we're going to see efforts to turn this into a power source be completely electrified by this news.
The best path forward for fusion
If what happened at Lawrence Livermore Lab does not present an obvious path to commercialization, what else is going on that seems more obvious? We differentiated between magnetic and inertial confinement fusion. Other people will point to deuterium-tritium fusion versus aneutronic fusion. Where is the most likely path, and does it come from government, from the private sector, that will lead us to a commercial reactor?
Of course, it's hard to know exactly, but we can certainly make some sensible guesses based on what we know today. To answer the second part about deuterium-tritium fusion or aneutronic fusion, just so your listeners are aware, these are about different types of fuel that we're putting into fusion reactions. So the first kind, deuterium-tritium, those are just special types of hydrogen. Frankly, all of the really serious attempts to do fusion today using these because they require much, much less extreme conditions than the other types of fusion reaction, though people get very excited about the type of fusion that doesn't produce any neutrons, aneutronic fusion, because it has less radioactivity. But it's much, much harder to do.
Would it be a better power source? Some people have said that with deuterium-tritium fusion, you would still need some sort of boiler. You'd be using a steam turbine, just like you would if it was coal. While aneutronic actually creates electricity itself.
In principle, yes. People haven't really demonstrated that principle in practice. But yeah, that's why people are excited about it, because every time you change energy from one type to another you lose some of the useful energy and you just have a more direct setup with the aneutronic fusion. But I think that's some way away. In terms of what's practical for the next steps to getting to an energy source, there are paths using both this inertial approach and using the magnetic approach.
Some of the private-sector companies are using this magnetic confinement approach. I think Commonwealth Fusion Systems, that's what they do.
That's right. And Tokamak Energy as well. There are pros and cons of both different approaches. In terms of the kind of approach that the National Ignition Facility is taking, there are some big technological gaps in terms of something that looks more like a power source. This was a single shot of a laser on a single experiment. If it was to be anywhere close to being a useful power source, they would have to do probably 10 shots on that laser a second. And instead of a gain of 1.5, so instead of getting 1.5 units of energy out for every unit of energy you put in, you'd have to probably get at least 30 units of energy out than you put in. Now, as I say, this thing scales nonlinearly, which means that you might get there faster than you think. But it's still a big technological gap.
And even if you solve all of that, of course you've then got to do what you said. Ultimately, we're extracting the heat energy and we're using it to turn water into steam, and we're powering a turbine. Now, what some of the people who are working on this magnetic confinement approach would say is that even if they haven't got to net energy gain yet, they have created a lot of gross energy. So they have generated about 30 times more gross energy than NIF produced in output energy in a single experiment. And they would say that some of the steps further down the line are a bit easier to achieve on magnetic confinement fusion. But honestly, I don't think we really know yet. And because we don't know, it's a good thing that we have both public and private sector exploring a range of different options here.
How seriously should I take anybody who gives me a date? How confident should I take any of these predictions at this point?
Well, that does depend, Jim. Was it the president of the United States who said this to you? Because I feel like he's got some control over it. I think the first question to ask when anyone says that is, at what level of investment? Because that's the thing that's going to make the difference. If we stop all funding to fusion tomorrow, if people decide to do that, then it's going to take forever. But equally, if President Biden says it's going to take 10 years, and he makes a commitment to put in the money that could potentially make that happen, then I'd take it a bit more seriously. I think 10 years is a very tight time scale. But as I've probably mentioned before we saw in the pandemic how even untested technologies can be deployed at great speeds, faster than anyone could have imagined, where there is the political will and the societal need and the money to make it happen.
The importance of fusion for an energy-abundant future
Why is this an interesting source of energy?
Nuclear fusion, it's interesting scientifically because every time you go outside on a sunny day, those rays you're feeling on your face from the sun are generated by nuclear fusion. So this is literally the reaction that lights up the universe. It's the reaction that created a lot of the elements that we are made out of, particularly bigger elements. And it was right there at the start of the universe as well, creating some of those fundamental building blocks of life. So it's an extraordinary reaction, and it's amazing to start to be able to control it. But there are practical reasons, even if you don't care about the science at all, to get excited about nuclear fusion as well.
It's potentially a very safe source of energy. There's just no chance of meltdown. It's not a chain reaction. If you turn off the laser or you turn off the magnets, the whole thing just stops. So it's hard to start, easy to stop. It also, as far as we can tell, isn't going to produce any long-lived radioactive waste. It will produce some from the reactor chamber itself, so not as a byproduct of the fuel, unlike fission. Maybe the reactor chamber at the end of the plant's life might be rated low-level radioactive for about 100 years as opposed to the potentially thousands of years in fission. So that's another advantage. I should say, though, that fission is an amazing power source and we should be doing a lot more with it. And actually, if you look at the data, it's very safe. But some people don't like it, regardless. It’s difficult to get it built. And then the other thing is that renewables are fantastic as well. They work today. They're never going to run out in any practical sense. But they do have this problem that they need to use a lot of land area or a lot of sea area to generate relatively small amounts of energy. I think you've always got pros and cons of these different energy sources.
You would need batteries, too, right? Because of the intermittency, potentially, you would need a lot of batteries. Big batteries.
Potentially you would need batteries too. Are batteries a bigger technological challenge than getting fusion working on the grid? I don't know. I'm probably a bit more relaxed about the batteries thing. Intermittency can be a problem with them, but also land is such a premium for other things — for food, for people to live — that I think that ultimately might be the bigger issue. And also people don't want to have these things built. They get blocked often. Whereas fusion and fission potentially — definitely in the case of fission, but almost certainly with fusion as well — the actual land area for the amount of energy generated is very, very attractive. So that's another reason. And finally, the fuel for nuclear fusion isn't going to run out anytime soon. There's enough of it on the planet to keep everyone on Earth…
The fuel for the kind of fusion we're talking about, deuterium-tritium, where does that fuel come from?
They're both special types of hydrogen. Ignore these quite wacky names. They're kind of special, rare types of hydrogen. But the thing is, they're not that rare. Deuterium is one of the ingredients, and about five grams of every bathtub of seawater is deuterium. So there's just absolutely phenomenal amounts of it in the sea. And chemically, it's exactly the same as normal hydrogen. So if we extract it, it doesn't really matter. It's not going to change anything, the fact that we're using it up. And then the other ingredient is a bit more tricky. It's something called tritium. It's very, very weakly radioactive. It's only harmful if you were to ingest it. But the problem is it decays over time into other things, so there's not very much of it around at any one time. But you can create it, and you can create it from another element called lithium.
Lithium is very common in the Earth both in ore and in seawater, and there's plenty of that to go around as well. Although of course, it does have some other uses, for example in batteries. So between those two, that's how you do it. Now there are problems: how do we turn the lithium into tritium, that needs to be solved on the kind of engineering side. But in principle, we've got enough fuel for thousands, if not millions, of years of energy for everyone on the planet to have the same level of consumption as people in the US, which you might be surprised to hear is quite high.
So this was net energy gain: more energy out than put in. But then you talk about wall plug energy gain in your book. Is that the next big step?
You know what, it kind of depends on where we want to focus our efforts, actually. There are a few ways we could go right now. For the benefit of your listeners, in this experiment, what they're measuring is the energy in, the energy that was carried by those laser beams to the target, and the energy that came out of that target from fusion reactions. Now, to actually power up and create those laser beams took a lot more energy. While about three megajoules of energy came out of the target, it took 400 megajoules to actually charge up the batteries, or the capacitor banks that they're called, to actually create those laser beams that had the two megajoules of energy. Wall-plug efficiency would be generating more energy than this entire system, so more than the 400 megajoules and more than the entire facility.
The thing to say about the National Ignition facility is it was built to do ignition. It was built to do the scientific bit. They never cared about the fact that their lasers are horribly inefficient, because they knew that wasn't really what they were aiming for. What I suspect they will do on this machine, which is really built for optimizing what happens at the target end, is to try and up the gain as much as they can. Perhaps to a factor of four or five times rather than one-and-a-half times as they've done here, which is probably about the limit of this particular machine.
But in the long run, of course, we've got to generate more energy than the facility as a whole. And that means probably going up to gains of at least 30 times. And eventually, if you're doing this form of fusion in a power plant, you'd use way more efficient lasers. This thing was designed 20-plus years ago and the laser efficiency is below 1 percent. There are lasers around today that can fire much faster and which have a 25 percent efficiency. And they're still not quite there in terms of energy terms. But with a bit more technological tweaking, maybe they could be. There are lots of ways to get over this wall-plug efficiency issue in the future. We haven't optimized for that. That is a good next challenge. But there are other parts of the problem that you could work on too.
When you look at what government is doing, what some of these private sector companies are doing, what ultimately is the path that you get most excited by and you're like, “I don't know for sure, but this could be it.” This is not investment advice!
No, it’s absolutely not. It really depends on what kind of a commitment… Assuming things carry on in much the way they did yesterday and the day before, which is not a given, of course, I think probably the most promising path is a big magnetic confinement fusion device called ITER, which is currently being built in the south of France. And ITER is very expensive and on a very big scale but will probably show net energy gain using the magnetic approach. We'll start to test out some of the engineering issues around a prototype power plant. Now, it is not a prototype power plant, but it will start to look at least some of those engineering challenges. I think one possible path for fusion could be ITER gets finished, they're successful in testing out net energy gain and showing it can work in the magnetic way, which I think they almost certainly will (previous experiments with magnetic confinement have got very close), and they'll test out some of the engineering things. And then the private sector could come in at that point and say, “If you're doing it on that scale, it's going to be really expensive and we're going to have really low learning rates” — the smaller you can make a technology, the faster you learn how to make it even cheaper. That could be the time when the private sector really comes in and says, “We can do it for you. We can make them smaller and cheaper, and therefore, we can make the learning rate higher, making this technology more effective.” But that's just one scenario. There are lots of other ones. If the US government, and maybe other nations too, decided to really, really push the laser-based approach, then maybe that could be the one where we see the most progress towards a prototype power plant.
Do you think some of these existing private sector companies, like Commonwealth Fusion Systems, I think another one is TAE Technologies, do you see them as legitimate players?
Absolutely. Some of them are working on really interesting approaches. And like I say, because we don't know what works, I think it makes a huge amount of sense to let entrepreneurs and innovators just see what sticks to the wall. A lot of them aren't going to get there, because a lot of the designs won't work or they'll have to pivot to slightly different designs. And that's absolutely fine. The ones that are looking at fusion reactions that aren't deuterium and tritium, I am more skeptical of, personally, because that reaction just takes so much more energy to get going. Obviously never say never. The one that I'm probably most excited about, on paper anyway, is Commonwealth Fusion Systems. What the public laboratories have done is build up this huge body of knowledge about what does work. And no one is anywhere near as far ahead as the public laboratories in the UK and the US and the international collaboration ones. They’re really the only people who've gotten anywhere close to doing this, because they're the only ones who've actually run with real fusion fuel for a start. Or at least they were until about two years ago. The thing that's quite nice about Commonwealth Fusion Systems is they're really building on tried and tested tokamak technology, but then they're saying, “Hey, the thing that really makes this work is having really powerful magnetic fields. So if we could just find a way to dramatically improve that part of the technology, we could make this dramatically smaller and dramatically easier as well.” I like that approach because they're really just doing this one change. And they've got some really promising technology to do it as well. Some of the advances they've made in superconductors are really exciting and probably stand alone as inventions.
Will star power take us to the stars?
Finally, we talked about the use case for fusion. It seems to me that there would be a strong use case, as you just mentioned, right here on Earth. But also in space, where we're going to need energy. I haven't really heard much of that mentioned in all the excitement about fusion, but I’ve thought about it, and I bet you have too.
I certainly have. Just for the benefit of people listening, once you are wanting to explore space — and I think it's part of the human psyche to want to explore unknown frontiers, so I think we want to do that; I think most people would take that as a given — if you want to go beyond the very local area, like the Moon and Mars, it's very difficult to do it with conventional rocket technology, because essentially you have to carry the fuel with you. Imagine if you are trying to have a wood-fired interstellar rocket: The amount of wood you have to carry with you is just going to make life much more difficult. It's going to be difficult to get into orbit and then to actually get the thrust you need.
Now, one of the great things about nuclear fusion is that it is the most high-energy-density, so amount of energy per kilogram, reaction that we have access to on Earth. It's the highest energy fuel stuff that we can possibly imagine, and it is basically the only one that is going to be able to do this longer-distance travel, because it can get us up to the speeds that we need to actually make some real progress across space. As I like to say, star power is literally the only energy source that can take us to the stars. So we should be doing it for that reason as well. Absolutely.