Daniel and Kelly talk about the surprisingly difficult task of finding the fuel to make fusion work on Earth
So many of the problems facing humanity today come down to one basic issue. Power. Do you need to stay warm in the winter? Power solves that problem. Do you need to find shelter? Power makes it cheap and fast to make concrete or build structures. You need to drink some water. Electricity can turn seawater into drinking water if you have the power. You need to keep your food cold. Refrigeration requires power. You want to run a factory in manufacture clothing. Power you want to travel around your town or country. Power you want to grow food in the winter. Power power, power, power, power power. If we had a plentiful source of cheap power that didn't cause pollution or produce toxic waste, it would transform society. It would uplift the poor, It would make being human a completely different experience. And for a long time, fusion research has promised exactly that. Fusion, the process that powers the sun, doesn't need exotic heavy elements for fuel the way our nuclear plants do, and doesn't make deadly toxic waste. It doesn't produce climate impacting gases the way fossil fuels do, and it runs NonStop, unlike wind and solar, So it'd be great if we get fusion to work. Of course, fusion has been a few decades in the future, or an embarrassing number of decades now. But it turns out that there's another question looming. Before we solve the physics puzzles and make the technology work, there's a surprisingly difficult task of getting enough fuel that we can use to power those yet to be made fusion plants. So today on Daniel and Kelly's Extraordinary Universe, we'll be asking do we have enough fuel for fusion?
Hello?
I'm Kelly water Smith and I love power.
Why that was awesome, Kylie? Toleeupguard there. Hi, I'm Daniel Whitson. I'm a particle physicist now, but as a youth I dreamed of being a plasma physicist, though not because I wanted power myself. So why because I wanted to bring power to the masses. I thought, Wow, fusion is the future. We're going to change the world. We're going to solve all the problems. Oh my gosh, it's going to be so exciting.
And I find fusion that exciting as well. And we wrote about it a little bit for a book my husband and I wrote called Soonish. So I know a little bit more about fusion than you might expect from a parasitologist. But one of the things about fusion that I came across while doing my interviews is that everybody would be like, yeah, yeah, yeah, fusion. I know it's the power of the future, and it always will be, because it always feels like it's ten years out, no matter when you talk to people as ten years out. But I feel like I've been hearing some exciting fusion related news lately that makes the discussion we're going to have today like timely and relevant. So what is your sense how much longer till we have fusion?
I know I'm gonna go on the record and predict when fusion will be commercially viable. We have a long way to go between now and fusion being a big part of how humans get power. We've also made a lot of progress, Like where we are today relative to where we were in the nineties when I was thinking about doing fusion research, like we are light years ahead of those nineties physicists, But I think we're also under selling how far we have to go. One of the things we're going to talk about on the podcast today is what you do after you make fusion work finding the fuel for it, and there are other technical problems that make it challenging to actually integrate fusion into our lives. But that's actually not the reason that I didn't become a plasma physicist. Why I didn't realize as a young scientist that you needed more than just the big questions of this field seem exciting, where the lofty goals of this project are worthwhile. To actually enjoy the work day to day, you need to have fun. And I didn't really like playing with vacuum chambers and lasers and all that kind of stuff day to day. I wasn't good at it. I didn't enjoy it, and we weren't bringing energy to the masses every single day. It doesn't really bother me these days in particle physics that I'm not discovering a new particle every day because I am having fun writing programs and solving little mental puzzles. I think a lot of people don't realize how important it is to actually enjoy the day to day grind of your science, not just the Nobel prize winning moments.
I totally agree with you, so I for my PhD, I was doing some like molecular biology stuff, trying to figure out how a parasite that lived on the brain of a fish was manipulating its behavior.
So I was measuring like hormones and neurotransmitters.
And I hate pipets, and I thought i'd love them, Like I have friends who just like they're having like they're in the zone, man, listening to music, and there's one with the pipette and I.
Just got angry.
And so, yeah, no, you've got to love the day to day otherwise it's not going to work out.
Yeah, and it's very personal. Some people love sitting in front of a computer all day long, and other people think that's not doing science. If you don't have a screwdriver in your hand, you're not feeling greasy at the end of the day, you're not doing science. But you know, everybody's got to find their bit. And the thing I love about science is that it takes all kinds. It takes computer nerds like me, and it takes screwdriver nerds, and it takes people who want to dive into dumb trucks full of smelly fish on a sunny day.
I mean, I.
Can't say I enjoyed that part either, but it was nice actually, you know, learning about new species of fish you find in Lake Eary.
That was fun.
So my number one piece of advice to like young scientists is to try a lot of different kinds of science because you can be excited about the big picture questions of cosmology or parasitology or geology, but if you don't enjoy the day to day work, you're not going to be inspired and creative because you're not having fun. And this can be really hard to tell in advance. So you got to dabble before you find your jam.
Yeah, And it can be so hard to feel like you have time to dabble because I know, you get into grad school and you're like, I have to publish all the papers or you know, depending on what job you want. But I always tell students like, yes, dabble. My advisor was really good about encouraging me to dabble, and who knows where it would have ended up if I didn't dabble. Got a fun combo of things going on.
But today we're not going to dabble. We're going to do one of our deep dives into a topic in physics to understand how fusion works, what we actually need to make fusion work, and where we can find that fuel if we even can.
So when you sent me the idea for this topic, it kind of blew my mind because I thought we had plenty.
Of fuel for funds all over the place.
And so I'm personally very excited about this discussion because it, you know, I like discussions where the angle is something that really kind of throws me off, and I wasn't expecting. And so here we go, and let's see if our listeners were thrown off or not. And if you would like to be the people who answer the questions at the beginning of the podcast, please send us an email at questions at Danielankelly dot org and we'll send you the question. You can send us an audio file and then we'll put it on the show. All right, let's see what the listeners thought.
I had no idea there was a fuel availability question for fusion, but from what I understand, it uses hydrogen and that's pretty much the most plentiful thing out there, So I would assume, no, there's not unless there's some challenge with making the hydrogen usable for fusion.
To find fuel for fusion, we need only look to the universe. Hydrogen is the most abundant thing in the universe, so surely there's plenty of it in our rocks and water on Earth. And once we figure out fusion, we can probably just go to the local styles and suck them dry like a sci fi dystopian novel.
I believe I've heard mentioned on the show that we do not have enough hydrogen to create fusion like the sun does. However, if we are talking about cold fusion, then I believe that we would have more than enough to accomplish this using seawater to pull the hydrogen from for that purpose.
I think, is this a true question? Yeah, Well, hydrogen is the most abundant element in the universe, and plenty of hydrogen around, and that's what basically we're gonna be doing, is turning hydrogen and helium, you know, via our tokemac shape or whatever nuclear fusion reactor. So yeah, hydrogen would be very easy to come by. If I'm missing something, Am I missing something?
I like that somebody else was like, is this a trick question?
What I take away from this is everybody has heard the propaganda that fusion just requires hydrogen. Most of the universes hydrogen. Obviously, that's not a problem. Let's move on to the real stuff.
I think we've all drank the hydrogen kool aid.
Ooh, there's a new product we've unlocked, right there, hydrogen kool aid. I guess all kool aid contains hydrogen already, right, because it has water. But we could sell it as fancy kool aid.
Yeah, no, absolutely. I mean, if people are buying bottled water, we can sell this too. And I buy a bottle of water sometype, So no judgment to the people who are buying it. Let's start at the basics. What is fusion and how does it work?
Yeah, in order to understand the challenges for finding fuel for fusion, we have to understand how fusion works. And some of the details are actually really important, but the basics are that fusion is sticking protons together. We know that elements are defined by the number of protons in the nucleus. The reason we call hydrogen hydrogen is because it has one proton. The reason we call carbon carbon it's because there are six protons. Yeah, another proton, it's no longer carbon. This is my least like subject in science high school. Chemistry I'm currently now teaching my second child who's going through high school chemistry. But basically it's alchemy. Right. You can take elements, you can squeeze them together, you get a new element. Right. That would like blow the minds of people from the sixteen hundreds that we really can change elements from one to the other by squeezing their nuclei together and getting those protons to stick together.
It's like magic because not only do you get something new, but you also get energy.
Yeah.
Yeah, and then you can try to capture it.
Yeah, but it's not the kind of thing that protons like to do. Right, you have an hydrogen atom, it's a proton and an electron. The proton and electron attract each other because they're opposite charge, and so they fall into a stable pattern. Right, there's a bound state there of the electron of the proton neutral hydrogen. But if you're trying to take two protons together, like the nuclei of those hydrogens and squeeze them together, what happens, Well, they are like charges. They're both positively charged, so they resist. Right. It's like trying to put two North magnets near each other. You know, they squirm and they slide and they try to avoid, and it's really hard to get them to actually touch. And the same thing happens with protons, which is why fusion is so hard. You can't just take hydrogen gas and watch it and see fusion happen, because those protons avoid each other.
If you can't actually get them close enough, then they stop repelling.
Right, Yeah, there are two things going on here at sort of a larger distance. The way hydrogen normally is. Basically, the electromagnet force repels the nucleid. They stay apart from each other. But if you get the protons close enough together, then they start to feel the strong nuclear force from inside them. And this is a little bit confusing because a proton is neutral in the strong nuclear force. So let's back up. We have a few fundamental forces in nature. You have electromagnetism, you have the strong nuclear force, the weak force, and gravity. Mostly it's electromagnetism that we talk about when we talk about elements and chemicals and bonds and all this kind of stuff, and it's those positive and negative charges that determine what sticks to each other and what repels. But these other forces are also powerful. In fact, the strong nuclear force is much much more powerful than electromagnetism, but mostly it's already neutralized. Like, a proton has quarks inside of it, and those quarks feel this strong nuclear force, but together all the quarks inside a proton are neutral, like they all add up to basically zero strong charge, which confusingly we call color. So a proton is neutral from the strong force and another done as neutral from the strong force. But if you bring them close enough together, then the quarks inside one start to feel the quarks inside the other, because like overall, on average, they're neutral. But if one of the quarks is sort of like near the edge of the proton, another one is near the edge, they will start to feel each other. So if you get them close enough together, that strong force attraction between the quarks inside the protons will take over and they will snap together and make a new nucleus.
And what gives you the energy when that happens is it the snapping.
If you put your ear really close to fusion, you can hear the snapping. It's amazing. It's just like pouring milk onto rice crispies.
Oh what a pleasant experience.
No, that part was a joke. It's a really good question where does the energy come from? And it's confusing because we have two forms of nuclear energy. We have fission, where you take really heavy elements and you break them up into lighter elements and you get energy. And then we have fusion, where you take lighter elements like hydrogen and you squeeze them together to make heavier elements and you get energy. And you might think, hold lot a second, isn't that cheating? How do you get energy in both directions? Making heavier stuff gets your energy, making lighter stuff gets your energy. Well, the answer is that those are very different configurations because if you start with anything heavier than iron, then making it lighter you get energy. If you start with anything lighter than iron, making it heavier, you get energy. If you take two uranium atoms, for example, and squeeze them together to something crazy super uranium, you don't get energy. And if you take two helium atoms and you break them apart, you don't get energy. So fusing light stuff together or breaking heavy stuff you get energy. And where does that energy come from? Well, in the case of fission, it comes from internal energy stored in the nucleus. It was like a spring that was compressed and it was bound up and you released it and the energy is released. In the case of the lighter stuff, it's a little bit more complicated. Basically, it was the energy of those hydrogen atoms and you could think of them as like flying around in space really really fast, and now they're stuck. They stuck together, and that where does the energy of their motion go. It gets kicked off as photons and other kinds of stuff. So they've sort of fallen into a lower energy state, a bound state together, and they've given up that energy when they do it. But that's very handwavy. The truth is, like it's really complicated in nuclear physics that we don't one hundred percent understand.
Okay, so the lighter stuff is what you use for fusion. It must be harder to join things together than break things apart, because we already use fission in nuclear power plants.
And because you're a parent and you know that, like breaking a glass is much much easier than putting it back together.
Yeah, so much easier, So much easier, or a.
Lego tower or something, Yes, exactly, it's pretty easy to have fusion happen. You just like have a nucleus, it wants to break apart. Like uranium is pretty unstable, you knock it with a neutron, it's just going to fall apart. It's not that complicated, but getting fusion to happen is hard because these protons will repel each other. Think of it like mini golf and you're trying to get the golf ball into the top of a volcano. If you get it right on the very middle, it's going to go to the top of volcano into the hole. But if you miss at all, it's just going to slide right back down the side. So to get these protons together, you have to have like the perfect shot, the right speed, the right direction. It's very unlikely for this to happen, even in like the Sun. Mostly protons avoid each other, even in the crazy high temperature, high density conditions of the Sun. The reason the Sun lasts so long is that fusion is very hard to do, and most of the Sun is not fusing.
When we think about doing fusion on Earth, we're using hydrogen. As you said, why hydrogen and not carbon? Is it even harder to smooth together carbons because it's low enough in that like break them apart to get energy. Divide that you mentioned. So why hydrogen and not like carbon?
Yeah, great question. Well, yeah, you get more energy from fusing hydrogen together than helium. You get less and less energy as you go up, and when you get to iron you get no energy and then it turns over and it costs energy to fuse them. So hydrogen fusion give you the most energy, and hydrogen is the easiest to combine and also requires lower temperatures. That's really the key. Like, to fuse helium together, you have to be even hotter than fusing hydrogen, and to fuse carbon together, you got to be even hotter. And fuse neon together, you got to be even hotter. That's why out there in the universe, some stars are big enough to make iron, but most of them aren't. Most of them will die out after the make helium or carbon and they never get hot enough to fuse that carbon together. It just stays there inert until the star dies. So the key is temperature. If you can get super duper hot and super duper dense, yeah you can fuse and make iron, but that's like elite stars, only some of those can make that. So here on Earth, where we're like doing a little baby fusion. We start with the first easiest steps, Like we have made fusion work here on Earth. We have fusion bombs. It's not great, it's how wonderful that we can do it. But fusion bombs start with a fission reaction, so it's like a classic atomic bomb, which then creates the necessary conditions for fusion and you get a massive release of energy. So a hydrogen bomb, for example, is a fusion bomb. So we know the physics, we know we can make it happen. The challenge is creating the conditions to make it happen long term, so you can keep pouring fuel in and keep getting energy out. And to do that you really have to get things hot or dense, or do it all really really quickly before it disperses.
That sounds hard.
I'm feeling like, if you to kick off this reaction, you need a fission bomb that doesn't bode super well for ability to contain it and use it to like power toasters. And so before we jump into how do you contain those conditions so that you can make power and send it out onto the grid, We're going to take a quick break, all.
Right, We're back.
So we've discussed how hydrogen bombs use fission to create the kind of conditions that you need for fusion to happen. But since we don't want to be setting off nuclear bombs and neighborhoods, how are we trying to create the conditions for fusion in a and friendlier ways.
So, if you want fusion to happen, the critical things are temperature, density, and time. Like if you can make your protons really really hot, meaning they're going really really fast and they're more likely to overcome this electromagnetic repulsion and fuse together, to get close enough to fuse together. Another trick is density, because the more protons you have jammed in there, the more they can't avoid each other and will eventually fuse. And then there's time. The longer you can maintain this hot, dense soup of protons, the more likely you are to get fusion going. And so basically we try all these different strategies. Like out in the universe, the stars use gravity. They're like, Okay, if we just get enough hydrogen together, it'll have enough mass. That is, the gravity is going to do the job for us, and it's going to make things hot it's going to make things dense, and it's going to trap it there forever. So starts sort of have it easy because they went big, and here on Earth we can't go that big. We can't just use gravity. So one classic strategy is to use magnets instead of using gravity to create the conditions where all the hydrogen gets squeezed together. What if we use magnets because magnets can bend the path of charged particles, Like that's basically what a magnetic field is. You have an electron flying through space, you put a magnet near it, it will bend the path of the electron. So now imagine you have a plasma which is basically just charged particles. You take hydrogen, heat it up, so the protons electrons are now flying free. It's a gas that has electric charge, and that means that you could use a magnetic bottle to contain it. So the classic strategy is basically a donut. Get the plasma moving in a doughnut and use magnets to keep bending it. It's like a racetrack and just zooms around and around and around. You have this hot, flaming plasma contained in a magnetic bottle and nothing has to touch it, right, You don't need something which can withstand three thousand calvin. So magnetized fusion is like heat it and then try to contain it in a bottle and keep it there long enough that you get some fusion going.
And so my brain has lost track of the names of some of the projects, but I think there's the biggest international project. Is this delicious doughnut shape doing the magnetized confinement fusion, right, And that's EATER, I think. And what does that acronym stand for.
What is EATER stand for? It stands for International Thermonuclear Energy Reactor. No, I just made that up.
Well, I was convinced you said it with the right level of confidence, and I was in.
No, EATER actually stands for International Thermonuclear Experimental Reactor, so I was pretty close. But you're right. The EATER is sort of the big Mama version of the classic strategy, which we call a tokomac. And the Russians were leaders in this for many years, and so a lot of the words in this field come from Russian, so I don't actually understand the origin of the word tokmac. But it's basically a magnetic donut and as you said, magnetically confined fusion. And the challenge is keeping it there and keeping it hot. Because plasmas are crazy. It's really hard to keep them stable. And as people watch them, they're all sorts of like fluid dynamics that's going on. So you have like electromagnetism with all these charges, and you have all the issues of like liquids and keeping things flowing without creating vortices and turbulence, and it's very unstable. Once you get like something spinning in a little vortex forming, you have electric charges in the mix, and then the whole thing just spins out of control and collapses. So mostly the last few decades have been spent trying to keep these plasmas calm, get them hot, get them spinning, keep them going for long enough that you can put fuel in there. It will fuse, and then the energy from that fusion will keep the plasma hot. So this is called ignition. It's like when you're trying to start a fire, right, It's first it's really hard to get that log going. Once you've got a hot logo, you can throw anything in there and it's just going to baby burn. Right. So the trick is getting this plasma hot enough that it sustains itself.
I am really bad at starting fires. Another reason it not be stuck with me in the apocalypse. Okay, so, if I'm remembering my fusion stuff correctly, what you want is to pass break even. And break even is the point where the energy that you put in to get this really complicated system going matches the energy that the system outputs. And ideally then you get way past that because now you can start powering new things. Has any tokamac hit break even?
It depends on exactly how you do the accounting from a commercial perspective. No, if you account like how much it costs to run the whole thing, including like the facility and the electronics and everything, then nobody has hit break even. If you're really creative with your accounting where you're like, I'm only going to account the actual energy I spent that went into the plasma or something, then there are some places that have achieved break even briefly, right, So briefly is the key there, Like they have put in fuel and it has fused and it has released energy. They have not captured that energy. Like, it's not like they turn that into electricity. That's a whole other issue for like, what do you do with his energy? How do you capture it and efficiently turn it into electricity. Nobody's done that even but we have achieved fusion with tokeomacs, and the idea is that this eater, this huge reactor, is going to scale it up and solve all these problems because these tokemacs actually get better as they get bigger, because their volume grows more quickly than your surface area. It's the reason that like an elephant has to cool itself with its big ears, is because there's so much meat inside and so much less surface area that it's hard to keep it cool. Well, that actually works in the benefit of plasmas. As they get bigger, they don't cool down as easily, and so there's like a hot, dense core the center that stays fusing. So that's why Eater, which is like twelve meters high, this massive doughnut. All the projections are that it will hit break even and actually generate power. Of course, it's taking like decades to build and zillions of dollars, so whether it's commercial it's another question, but it's sort of tried and true.
Okay, Yeah, that's what I was wondering.
If it's that expensive, is it really going to be feasible to like PLoP one of these in you know, every state to power stuff. But you know, I guess you get better at it and then you can get economies of scale and stuff like that.
But okay, you could just build them in space. Everything's easier in space, right Kelly.
Oh my gosh, yeah great.
Where is the We need to find an angel investor for you, because you, I think are onto something.
Everybody should invest in my fusion AI crypto startup.
That's all the words. You've got this.
I get all the monies, right, well, I helped you think about it, so I get half the monies. Okay, so we've done. Okay, so magnetized fusion, this is clear. The tokemacs are clearly the most delicious way to think about fusion. But maybe the most epic way to think about fusion is the laser version. And so how does the laser version work?
The laser version says, let's give up on keeping the fusion going for a long time. Instead, let's go for super high density like this, have really brief fusion, but make it really good because we have high density because fusion happens more rapidly at higher densities, Like as you squeeze those stars together and the cores get hot, you get more fusion faster. This is why like big stars burn out faster in the universe than slow stars. They have more fuel, but they burn hotter. The fusion happens more rapidly. They burn out in a few brilliant million years, whereas small stars can burn for like billions or trillions of years. The idea of laser fusion, sometimes called inertial confinement fusion, is you just take a pellet of fuel and you zap it with intense lasers, like one hundred and ninety six lasers from all directions. It's like super futuristic and awesome looking. And if you zap it from all sides simultaneously, basically the outer layer explodes, which compresses the whole pellet, and then you get the density you need for fusion. So you have this shockwave. It's like a mini supernova. The shockwave travels inwards at like three hundred and fifty kilometers per second. We're talking these tiny little pellets in this super fast shockwave, and this fuel goes from like the density of water, you know, one gram per middle liter, to one hundred times the density of lead, and that's where the fusion happens.
That this method works at all kind of blows my mind because anything that requires like incredible amounts of coordination. Like I think about my family and there's just four of us, and I'll be like, we all need to meet at the same place in fifteen minutes, and nobody's there at the right time. But somehow you're getting like all of these lasers to sort of time up and shoot the same exact tiny spot at the It's kind of amazing to me that the coordination problem here has been solved or is working on being solved.
Well, it turns out electronics are more reliable than children.
Yeah, I guess that's not surprising.
Yeah, But the whole thing happens in like ten to thirty nanosecond time period. It's super fast, and the reason it works is like you're squeezing the fuel by huge factor, so you're not containing it for very long because now it's super tiny, but the density goes up much more quickly than you're losing seeing the time, and the fusion goes up with the density. It's another one of these dimensional arguments, like if you squeeze things down by a factor of ten, it lasts for ten times less long. But the density goes up by a factor of ten cubed, as does the fusion. So higher density also means the heat is not lost, like the alpha particles that you're creating in this fusion don't escape. And so the calculation suggests this should actually work. And in the last few years they made huge progress and the National Ignition Facility, Lawrence Livermore National Lab, actually made this work and like, got fusion happen from these little pellets?
Whoo? And so do you blast the pellets with the lasers?
And then how so we were talking about how you want this reaction to keep going and take more time so that you're getting more energy out of it. Do you just keep blasting pellets over and over and over and over again or do you blast once and that gets something going?
And then you contain that yes.
So basically each pellet is a one shot operation. And if this ever were to work, you zap the pellet, you get the fusion, replace it with new pellet, zappit get fusion. This approach is giving up on time, right, the magnetic confinement is saying, let's try to keep this going as long as possible so it builds on itself. Here they've given up on that, and they're like, let's just have a rapid series of fusion, each one independen, so don't benefit from the previous one. You start from scratch with a new pellet every time. But it means you have to have these pellets and you have to prepare them. They're these like tiny little fragile dots of special hydrogen and they're not cheap to make.
All right, So some economic problems that also need to be solved. But is that the two ways to do it or is there a third way?
Those are the two main ways, magnetic confinement or inertial confinement, basically like magnets or lasers. These days, there's lots of clever ideas out there in the business world, and you start to see startups coming up with their own idea for fusion. They're like, these big government funded ideas are too slow and too conservative. I have my billion dollar fusion idea. And so there are some companies out there that have private funding that are working on variations of this. Like there's a company called Commonwealth Fusion, and their idea is, you don't need to make your magnetic confinement so big, you just make the magnets more powerful. So they're using like super conducting magnets to make like a smaller version of eater that they think also is going to work. And those are serious scientists, Like these guys know what they're doing. They publish academic papers, they have real money. This could really work. And then there are other crazier ideas. There's one here in southern California called tri Alpha Energy where they have a plasma which is contained magnetically and then they shoot a particle beam into it because they think they can make this like special resonance coil happen where it like spins in a certain way that makes magnetic fields that help stabilize it instead of destabilizing it. The basic idea for that whole company was created by a professor here at UC Irvine a few decades ago, and so a lot of people believe that that could really work. Then there's the one Sam Altman is funding Helion Energy, and they're using some combination of these two ideas lasers and magnets simultaneously. But the bottom line is that all these differ and approaches all use the same fuel. It's all hydrogen, and it's all the special version of hydrogen that you need. In every case. The challenge is getting the high temperature, maintaining the high temperature, or creating that high density to make fusion happen. But it turns out that doing fusion with pure hydrogen, like the kind that most of the universe is made out of, is actually much much harder than doing it with special fancy hydrogen.
Tell me about this special fancy hydrogen. Am I going to like try to capture it in a locket?
Is it that kind of fancy? What does it look like?
Yeah, give it to your partner on their birthday. So we heard at the top a lot of people thought, well, fusion is great because the inputs are hydrogen, and hydrogen is everywhere, and it's true that most of the universe is hydrogen. Like way back in the beginning of the universe, things were still cooling down. You had protons and electrons flying around mostly that just cooled into hydrogen. Very briefly, there were the conditions to make heavier elements a little bit of helium was made, but mostly from the beginning of the universe was hydrogen. And stars have come along and fused a bunch of stuff to make heavier stuff, so that it's me and you and lava and kittens and all that stuff. And we have iron now, but that's still a tiny fraction of the universe. Most of the universe is still hydrogen. So this seems great. We have a power source which requires a fuel, which is most of the universe. How could it be any better? Right? And often you hear fusion's fuel described as abundant, virtually inexhaustible, and equally accessible to everyone. So this seems amazing, right, And we have like oceans of water water has filled with hydrogen. So in principle this sounds great, but as always with science and with commercializing science, the details are important because it turns out that fusion is hard to do with sort of vanilla hydrogen. You have this two protons, you us squeeze them together. You can do it, but it's gotta be really hot or really dense. It turns out it's a lot easier to make it happen if one of those protons has a neutron friend along. For the ride. So if you have hydrogen, but you add a neutron to the nucleus, so now the nucleus is like a proton and a neutron. It's still hydrogen, right, It's still just one proton, but now it has a neutron friend, and that makes it a lot easier to squish together with another proton because the neutron helps mediate it. Neutrons make nuclei more stable. They're neutral. They don't play a role electromagnetically, but for the same reason, like they have quarks inside of them, and those quarks have the strong force that neutrons help things happen. And so it turns out that using deuterium, which is what we call hydrogen, with an extra neutron, makes fusion a lot easier. It can happen at lower densities, it can happen at lower temperatures.
So how many hydrogen protons have neutron friends? How often does that happen? I hope they're not lonely that often.
So not very often. It turns out that out there in the universe, one in about sixty five hundred hydrogen atoms has the neutron friends. So deuterium is not very common, but deuterium is actually not even the best source. What we really want for fuel for fusion is something called tritium. So deuterium we call deuterium, has that prefix in it from Latin, which tells so there are two particles in the nucleus, the proton and the neutron. Tritium is if you have a proton with two neutron friends, that's tritium and tritium. Deuterium fusion together is like the best. If you have deuterium and tritium, you got like two protons three neutrons to help out. This thing is the easiest to make happen. So a lot of the fusion that we've succeeded to do here on Earth, what we talked about for the ignition facility, those pellets have deuterium and tritium in them, and the tokamax also use deterium and tritium for fuel. So even to make it work here on Earth, we've relied on doing it the easy way, which means using these rare special kinds of hydrogen.
So why wouldn't tritium and tritium be even easier than deuterium and tritium.
Tritium tritium, you can make that work also, I think deuterium and tritium work better. This is complicated stuff like getting the neutrons to play along and how that all happens. You know, there's a lot of complicated strong force interactions that we still don't understand. We still don't really understand what makes a nucleus stable. This is a really cool theory about the shell model, about how these things slide into each other, sort of like electrons. How you want to fill orbitals and make them complete to make something inert, and in the same way you want like the same number of protons and neutrons they like complete shells. Anyway, the short answer is it's very complicated. But there's one other fuel we can use to make fusion easier than like vanilla hydrogen, and that's actually a form of helium called helium three. Helium is two protons, but it's actually not even stable that way. Like you have just two protons, they will not stay together. You need neutrons to hold that guy together. So if you add a neutron, you can have something called helium three. So it's two protons and a neutron, and this is a lot of the fusion that happens in the sun. For example, helium three fusion produces helium four and hydrogen, and it's actually great for fusion because it's low temperature, it produces a lot of energy. It doesn't produce dangerous neutrons which can fly through everything and kill people, and so helium three fusion is fantastic. So the bottom line is vanilla hydrogen hard to fuse with. You need really high temperatures and pressures. Heavy hydrogen or helium three are the best. That's what we really need to do fusion.
So two different questions. First, you talked about the neutrons shooting out and killing people. This whole process still has less like radioactive waste and danger than fission, right, but with hydrogen you still have some rogue stuff you gotta worry about.
Well, you don't have the byproducts in the same way. Like when you start from big messy radioactive nuclear like uranium or plutonium, they're going to break down into big, messy, poisonous stuff. And that's the problem with fission fusion. You start with hydrogen, which is basically innocuous, and you make helium, which like ya makes you talk like a squirrel, so there's no like dangerous byproducts that way. But sometimes when the energy comes out, it doesn't come out in the form of photons like light that you can just gather, comes out in the form of really high speed neutrons that are ejected in these processes, and neutrons are bad, like if you heard of a neutron bomb. Neutron bombs kill people, and they do it without destroying a lot of the buildings. It's really terrifying because neutrons don't have a charge, so they can fly through a lot of material, but if they fly through your body, they like tear your delicate biological machinery to shreds, and so neutron bombs really insidious, which means if you're going to like capture the energy from some of these reactions, you need a way to like capture these neutrons and slow them down and extract their energy. But they're also going to end up irradiating your facility, so you will produce irradiated materials, like your fusion reactor will become irradiated. It's not as bad as what fission makes, and some people argue, hey, even fission isn't that bad, but it's not true that fusion produces like no dangerous radiation.
At all, But would it produce no dangerous radiation at all if you use helium three?
Yeah, there are no neutrons that'll come out if you just use helium three, So that's nice. It comes out in terms of photons, and you can capture the energy more easily. And I'll say that like, in almost none of these fusion efforts have people really spent significant time figuring out how to capture this energy. It's mostly like how to make the energy, how to like actually turn that energy into electricity and factoring and that inefficiency and the difficulty is not even like really begun. People are just still working on step one, which is like get fusion happen, And they were like, oh, we'll figure that out. That's an engineering problem, but like the whole thing is an engineering problem.
It's engineering problem stacked on top of each other.
Really exactly.
Let's take a break and then we're going to talk a little bit about how and where we find these things on Earth. Okay, we're back, and first I actually want to start with another helium three question for Daniel, because I'm kind of obsessed with helium three. So my question is, I think you mentioned that most of the reactors that are running today are using like deuterium and tritium. If that creates some radioactive waste and doesn't work as well as helium three, why aren't we using more helium three in reactors right now?
Yeah, great question. Well, the answer is that helium three is rare. You know, we don't have a lot of it, as we'll talk about it in a minute. I'm sure like there's some on the Moon, but there's really not a whole lot here on Earth, and so it's easier to find tritium and deterium. And this is a lesson that like the easier the source of fuel, the more likely you are to use in your research and define practical solutions. And so there's a whole chain here that's required to make fusion actually change the way our lives work. And there's a step in the middle there, like assuming you have all the fuel and a way to capture the energy, get fusion to work, and that's like where the physics is. So people have focused on that, but you got to make the whole chain work, and there've been discussions about like how to do step two, which is like a have to give fusion work, capture the energy, but not enough. I think about step zero, which is like have the fuel on hand to actually get this going. And so you need sources of deterium and tritium and helium three to make this practical.
So where do we get those now?
So deterium we find in seawater, because water is like one in sixty five hundred atoms zero point zero one five percent is just naturally deterium. It was like made in the early universe, you know, when these protons were cooling and sometimes they came together and one became a neutron. This beta decay and inverse beta decay and all this stuff. And so some like fraction of hydrogen is just heavy hydrogen which makes heavy water, and so we can filter it out. And India is actually the leading producer of this stuff. You start with water and you isolate it, use all sorts of like chemistry tricks because deterium is heavier, right, and so centrifuges and all sorts of other stuff centrifuges and complicated distillers, et cetera. But you got to filter it out of seawater and so it's not like you can just scoop up water or gather hydrogen and you have fuel. Your fuel is like one sixty five hundredth part of the hydrogen that you've gathered. So that's not easy. It's like a whole production chain that you need.
So if we could make that process easier. There's loads of seawater, so there'd probably be enough deuterium to run fusion for generations, presumably, Is that fair to mm hmm.
Yeah, deterium is probably solvable. There's lots of sea water and so there's lots of heavy water out there. It's just not as accessible as people think. And it's going to cost energy, you know, so you're gonna have to factor this in. It's gonna be a huge cost upfront. You're gonna sink energy in to get your fuel out. It's not as easy as like I can scoop up hydrogen and I'm there. And also deterium is not enough, Like if you just ran these reactors on deterium, we couldn't make that work. You really need the tritium to make these reactions happen, and tritium much more complicated than deterium. Unfortunately.
All Right, tell us about that, how much more complicated?
Well, the problem is deterium is naturally stable like hydrogen, as a proton and neutron, it'll hang out forever. A lot of that is billions of years old, but tritium is not a proton and two neutrons in there. That falls apart. The half life is only like twelve and a half years. So even if the universe made a bunch of tritium, it's like all gone now naturally, And if you make it, you can't like store it for a long time. It's just like your bottle of tritium just turns into deterium naturally, and so on. Earth is like a very tiny amount in the atmosphere made constantly by cosmic rays. Particles from space common hit a piece of the atmosphere, and sometimes tritium is made just like by chance, one of a thousand things that can happen. But mostly we get tritium by manufacturing it here on Earth by shooting neutrons at lithium.
Okay, so that sounds like we're talking about typical nuclear fission reactors, right, So this is a byproduct of that.
Neutrons are a byproduct of fission. And they are byproduct diffusion. So this is actually a little bit promising because you can imagine like a fusion reactor that pumps out neutrons. Then you surround that with a lithium blanket, and the lithium blanket absorbs the neutrons and makes tritium for you. So this's called a breeder reactor, where the reactor itself helps you make the fuel for the next round.
What a creepy name for reactor?
A creepy name.
It's kind of a creepy name anyway.
It sounds like a groomer reactor or something. Yeah, you're gonna come back. There'd be like two reactors because they've been breeding. No, they don't make more reactors. They just make their own fuel, which is cool. So if you have a special kind of lithium called lithium six and you shoot it with neutrons, it will make tritium. That sounds great because neutrons are a byproduct of fusion, and so if you put your lithium six near your fusion boom, you get your tritium, which you need for your fusion happy days. The problem is that you need lithium six, which is a special kind of lithium. Most of the lithium out there is lithium seven, so lithium six is much more rare than lithium seven.
You know, usually I'm the one who's like bumming people out, but I'm I'm feeling a little bit stressed listening to Utah. But we're gonna okay. So, but the point is, we haven't really tried this yet. Lithium six is hard to find, but it's out there, and maybe we could get good at this.
Maybe, although you're right that we haven't really tried this. Like I asked a plasma physicist in my department, and he was pretty skeptical. He said, quote hid the list of fusion reactor items that have worryingly low technical readiness levels is the lithium blanket. Can it really produce enough tritium without requiring too much surface area around the reactor. So like, in principle, we can do this shoot neutrons at lithium six, but like, can we actually make this effective enough? And can we have enough lithium around the reactor to make enough fuel? It's like something nobody has figured out, and it's also complicated to get this lithium. For another reason, which is that lithium is in high demand by the electronic car industry. Everybody wants lithium for batteries, and so most of the lithium in the world goes towards batteries.
They want lithium six, they.
Don't actually care, they want lithium seven or six, they don't care, but they just gobble it all up anyway. So if you wanted to imagine like a best case scenario where fusion is providing like thirty percent of the power to the human race, you might think, like how much lithium do you need. You'd need like ten thousand tons of lithium six, which would mean you'd need to like divert it from the current lithium stream, which is very complicated and we're not good at that. And mostly the folks who are selling lithium just want to sell it to the electric battery folks and not like filter out the lithium six. But you know, there's ideas here, like recycling the lithium or something, but you know it's you see how it's complicated and fragile. Like to do fusion, you need treatium. To make treatium, you need lithium lithium is not that easy to find and in high demand by other folks. Bill Heidebrink told me, quote, there is great concern about having enough treatium for deterium tretium fusion. Like it's basically an unsolved problem. It's not unsolvea bowl, Like potentially we can find solutions to this, but like people haven't really gotten kracking on this. Been working on the physics part of it for a long time because that's fun, but digging into the details of like actually having a production pipeline for fuel for fusion to get enough of this going has not really been addressed.
So how much harder is deuterium deuterium fusion? If the tritium appears to be the hardest part to solve.
It's possible. It just requires significantly higher temperatures, and so it makes the whole problem harder. Like we've barely gotten this going with deuterium and tritium. And if we gave up on tritium and said we're just going to do deuterium because you're right, there's more of it and it's easier to access and we don't have this whole production pipeline issue, it means that we have a much harder problem to solve on the physics side, So we're like now more decades away from really getting that to work. So it's about making the problem easier and deterium by itself, it just requires much higher temperatures.
So tritium hard to get. Helium three. Now, let's move to helium three. So we're stuterium tritium reactors. We're focusing on helium three. You told us earlier that it is hard to get on Earth. It does exist on Earth, though, is there any way we can make it on Earth or do we need to find it naturally occurring?
So helium three like existed on Earth a long time ago, but most of it bubbled out into space, and we can make it on Earth. Actually, we know how to do that. You know, you need to make helium three tritium. Yeah, so if you had plenty of tridium, making helium three would not be that hard. Fortunately, there's a huge supply of helium three right next door, and you know, every problem is easier by going out into space. And so it turns out that there is a significant amount of helium three on the Moon because it's been deposited in the upper layer by the solar wind, like stuff pumped out from the Sun. Helium three is made in the Sun, and the Sun is not just pumping out photons. It's pumping out protons and electrons and sometimes helium three nuclei, and those are deflected from the Earth because of our magnetic field or absorbed in the atmosphere. But the Moon has neither of those, and so it just like gathers up helium three. So a lot of people who talk about going to the moon and say, ooh, another benefit of going to the Moon is that it's really rich in this excellent fuel that we desperately need for fusion here on Earth. So tell us, Kelly, why is that actually a terrible idea?
All right?
Well, so first I'll say there's a space settlement advocate named Robert Zubrin, and I think he and I disagree on almost everything, but I think we feel the same way about helium three, which is to say, if we get fusion reactors going, and you're already living on a place like the Moon, then it's great that helium three is there and you can extract it and you can use it there, But is it going to be economically viable to collect it on the Moon and bring it.
Back to Earth. All Right, this is going to be tough.
So all right, first of all, the equipment that you would need to launch is going to be incredibly heavy, so it's going to be really expensive to get it there.
This is equipment to like take regolith and extract the helium three out of it, which you're saying is not trivial. You're not just like finding cannisters of helium three in the moon.
Yeah, there's not like helium three ingots that you can like go and collect and it's in the regolith, but it's not There's more of it than you find in like typical dirt here on Earth, but there's not loads of it. So you're still going to need to like sort through like football fields worth of this stuff in order to get like small quantities. And we've talked about that regolith. It's super abrasive. It's going to beat up your equipment that was probably expensive to send there already. It's in this harsh environment, the vacuum of space. If you're at the equator, there are these massive temperature swings that are like really hard to even make lubricants for, so that your equipment can run. So this is going to be a very difficult environment to work in. It's going to be very far away. It's hard for me to imagine that this could possibly be economically viable in many decades to come. So I'm not convinced by people who are like, oh, let's go out there and collect helium three for nuclear reactors that don't even exist yet, and that's going to make the moon profitable.
Anyway.
I could go on, but I'm spitting on the screen already and all stop there.
It's gonna be difficult.
Yeah, which is a bummer. It feels like all these potential sources of fusion I'm like right around the corner, just at our fingertips. But then there's always some frustrating technicolity between us and it. The fact that the helium three is there and on the moon, and just like if we could somehow get it here, it would be so great. But that process of getting it here can just like instantly rearrange the universe the way you want it to be, right. Unfortunately, that takes energy, it takes time, and it takes money. And these are all the realistic obstacles to getting fusion to work.
All right, so say tomorrow commonwealth fusion is like bam, we hit break even and now we're gonna fly past it. Do you feel like there could be a way that we could have fusion powering every home on the planet, or these problems, just like insurmountable fusion at its best could only service a small portion of humanity.
I think the answer is we don't know yet. There are important technical challenges between us and everybody has a fusion reactor at home or even this like a neighborhood fusion reactor or whatever. Can we make enough tritium scaling up? Can we find enough lithium six? Probably? I think the answer is probably. But these are hard problems and they haven't really been dug into, which means there are hard problems we haven't discovered yet. You know, when you really get into the nitty gritty, you're like, oh, wow, actually we thought this was going to be dot dot We're there. Turns out there's a really tricky bit here that nobody's solved, and you've got to struggle with it for ten years, which is why fusion has taken so long. You know, people have like skimmed over the surface of the concepts been like, oh, we understand the physics, it happens in the stars. I'm sure we'll figure it out. Well, figuring it out has taken decades, and this just means that there are decades more than even reasonable moderates about fusion tell us, because there are so many more pieces to this chain for actually integrating it into our society.
But to sort of throw everybody for a loop here, I'm going to be a bit of an optimist because, like, I know, I know, hold on, even are you well, no, it's you know, it's qualified.
It's qualified.
So I feel like, you know, if we figure the fusion thing out and it becomes clear that this could be, you know, not only a way to provide clean power to a bunch of people, but also a source of revenue, I imagine that you're gonna get like a bunch of startups and a bunch of like, you know, smart people working on this problem. And that doesn't solve all the problems, but I bet that once we get to that point, we're gonna unleash a lot of excitement and like maybe a lot of innovation, and maybe we'll be surprised at how fast this problem gets solved.
I can hope that'd be wonderful, and I agree with you. I think we probably will figure it out. You know, we're smart, people work hard. There are brilliant creative people out there, young minds listening to this podcast inspired to go into fusion thinking I can solve this treating problem. Go do it. I think it probably is solvable, but it does need to be solved. And so it's not just like once we've cracked the physics case in step four, all the other steps just fall by the wayside. Still got to crack them. But for some people that's their jam, you know, like Ooh, I'm excited about working on lithium blankets. I've dreamed about it since I was a kid, or you know, these puzzles are exciting to people, which is great, and I love that about science that people who are going to nerd out on how to get these fuels or how to extract them, or how to manufacture them, or how to negotiate with the battery industry and make sure that our lithium six gets filtered out of the mining process and they can have the rest of it. You know. So yeah, I think probably we will solve it. I agree with you that once we make the fusion step work the physics part of it, we figure that out, the rest will There'll be so much excitement and so much pressure and momentum that we will figure it out.
I mean, I imagine being the person who figures out the lithium six problem, like the implications of your life for life on this planet, Like that would just be incredible to feel like you had contributed to something so important.
Yeah, it would be incredible.
But I study bugs.
I can't imagine it would be like to work on someone that's actually practically useful both for people day to day. And you know, I have this experience all the time because I meet people with my wife and we talk about what we do and they're like, oh, yeah, that's interesting. But then there have a million questions for Katrina, who works only you know, like the human health and the gut and what people eat, and she's like immediate knowledge that's relevant for people's day to day lives and like, hey, you're a nerd about either way the universe works. We can talk, But if you want advice about chia seeds and how to have you know, healthy bowel movements, talk to Katrina.
Oh man, when do I get to meet Katrina?
Yeah? Exactly. You see what I mean. She's more more interesting than it's like. It's fine. I've come to terms with it. No, I mean. One of reason I'm but into particle physics is because it had no immediate applications. My parents work at the laboratory in Los Alamos, the work on weapons programs. That's terrifying. I don't want my research to be used to build weapons of mass destruction that are pointed at civilian populations. But it also means that I can't really help anybody day to day except for stimulating their curiosity of.
The universe, which you do so well.
And we'll be back next time with more stimulating information about the universe.
Thanks everyone for taking this ride with us. And I'm still in the end an optimist about fusion.
Me too. Go fusion people, figure it out please.
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