Let’s talk about a technology that could change our whole energy system, but so far hasn’t generated a single watt. In the season finale of TILclimate (Today I Learned Climate), Plasma Science and Fusion Center Director Professor Dennis Whyte sits down with host Laur Hesse Fisher to talk about fusion energy. Go to: https://climate.mit.edu/podcasts/til-about-fusion-energy
DW: [00:00:00] This is the classic joke. If anybody’s heard anything about fusion, it’s the perfect energy source that’s 30 years away and will always be 30 years away. Like, I hate that joke so much. I hate it so much. I’m dedicating my life to eliminating that joke from the English language.
LHF: [00:00:23] Welcome back to Today I Learned: Climate, the podcast where you learn about climate change from real scientists and experts. I’m your host Laur Hesse Fisher, with the MIT Environmental Solutions Initiative. Today’s episode concludes our series on energy and climate in partnership with the MIT Energy Initiative.
Our guest is an expert on a technology that could completely change our global energy system -- but, so far, hasn’t powered a single lightbulb.
DW: [00:00:59] My name is Dennis Whyte, a white with a Y. um, and I'm a professor, uh, here at, at MIT, and I'm also the director of the plasma science and fusion center of MIT.
LHF: [00:01:11] Professor Whyte studies fusion energy, which is the process that our stars use to generate so much heat and light.
DW: [00:01:20] Stars, by the way, and our own sun, is just a big ball of hydrogen. Most of the universe is hydrogen. So hydrogen is the simplest and most abundant element by far in the universe.
At the center of a sun and a star, it becomes hot enough and there's enough pressure that the hydrogen that wants to stay hydrogen is forced to get close enough to another hydrogen and they fuse, and they produce helium. And when that happens, it releases staggering amounts of energy. It's 20 to a hundred million times more energy release per particle than you can ever get out of a chemical reaction.
LHF (from interview): [00:01:59] So you're saying that the kind of energy that we can produce right now by burning coal and burning natural gas is just absolutely nothing like the kind of energy that you can produce with fusion.
DW: [00:02:09] That's right.
What we’re after, is bringing the power of the stars which is essentially inexhaustible, down to earth, to mankind.
LHF: [00:02:20] OK but if fusion normally happens inside a star, what does it look like here on Earth?
DW: [00:02:27] So what we, in the end we make is it has, it's actually a rather modest looking object that's got some high tech inside of it, but what we're making is a magnetic cage. It looks like you have a big piece of steel kind of, but it’s not that large. It’s about the size of a coat closet.
So first thing that we do, we get all the air out, we build a steel chamber and we evacuate every particle. This is basically a vacuum, like outer space. Then we put in a little bit of the fuel, hydrogen. But teeny, teeny amounts, And then we zap it with some heat and get it hot really quickly.
The challenge of fusion is that fusion happens in one place, in the center of stars, cause it's the one place that can get hot enough to make fusion happen. So at its heart it’s about getting the fuel, the hydrogen hot enough.
LHF: [00:03:15] How hot does it need to get?
DW: [00:03:17] Um, so the center of our sun is about 15 million degrees... Celsius.
LHF (from interview): [00:03:23] Celsius?
DW: [00:03:23] Celsius. Celsius.
LHF (from interview): [00:03:24] And what is… I mean in Fahrenheit?
DW: [00:03:25] Oh I don’t, I’m a scien--, we don’t, we never use Fahrenheit. It’s about like 25 to 30 million Fahrenheit. Sorry, I never think in fahrenheit. So it turns out to make it work on earth, it has to be at about a hundred million degrees.
LHF (from interview): [00:03:38] That's inconceivable.
DW: [00:03:39] Yes. Most people just like sort of have a, you know, a guffaw moment, blah. Like what, what, how can that be possible?
We as humans have almost no intuition about what something feels like at that, because we can literally never touch it. So we're used to thinking of a temperature, right? I mean, but over a pretty- ice cold or lukewarm water. You've touched an oven, it's really hot. This is really an incredibly small range of temperature.
LHF: [00:04:08] Right, things can get a lot hotter and a lot colder than what we experience in our daily lives. When you crank up the temperature to thousands or millions of degrees, something fascinating starts to happen.
DW: [00:04:23] Ice. What happens when you heat it up? It melts? It becomes a liquid. What happens if you then put that liquid on your stove and get it hotter. It becomes steam, it becomes a gas. So turns out though, if you take that gas and that steam and you keep making it hotter, uh, actually at about 5,000 degrees, something really fundamental changes in matter. It becomes a different phase of matter again. It becomes something called a plasma.
LHF: [00:04:48] You might have seen pictures of plasma on Earth -- lava, from volcanoes. Lightning also, actually is plasma. You may have also seen closeup pictures of the surface of the sun – the tumultuous surface and solar flares are also examples of plasma. And that’s what’s inside Prof. Whyte’s fusion chamber.
DW: [00:05:09] Something at a hundred million degrees sounds dangerous.But it's actually the opposite. It's because it's, um, to use a technical term, it's so far out of equilibrium with the rest of the earth, blowing on it actually turns it off. My breath is at room temperature and there's more particles in my lungs than there are in, in the fusion.
The listeners can't see this, but you'll see where I'm doing. Like I just, I like blowing out like a birthday candle. That would extinguish the fusion immediately inside of this.
So it turns out that that's actually the objective that we have achieved quite routinely is a hundred million.
LHF: [00:05:48] Right, actually getting the temperature to 100 million degrees -- which is still inconceivable to me -- isn’t actually the biggest challenge of producing energy from fusion. It’s about getting all the conditions in place to keep the fusion reactions going.
DW: [00:06:06] We need to supply heat to actually get it hot. So the equivalent is thinking like of a match. You put a bonfire together, here's a match. That's the initial source of heat. Then the bonfire, it lets itself keep going. We've never made the bonfire. Like we've lit the match. We've gotten the wood hot, we studied it, but it never took off.
And what that requires is actually that you're making so much fusion energy that is keeping itself hot primarily, and you're making a lot more energy from the fusion than the heat that's required to make it hot.
LHF: [00:06:41] Yeah, and that’s how stars work -- they are made of hydrogen and are able to keep fusing together hydrogen atoms into helium, making a chain reaction of fusions that’s able to sustain itself.
And so that’s the challenge here on earth: keeping the chain reactions running long enough so that it generates more energy than we’re putting into it to get it that hot in the first place. But the prototype that Prof. Whyte works with here at MIT is one of the most advanced examples of fusion energy on earth, and he thinks he’s getting close to having this happen.
DW: [00:07:18] How does this look like in the real world then? If you just draw a box around the exotic part it just looks like a heat source...
LHF (from interview): [00:07:25] So then it, does it boil the water and produce steam and turn a turbine? Or what...
DW: [00:07:29] That's one of the things you can do with it. Um, that's actually, you know, we think we can actually be much more efficient than that. Cause one of the features of fusion is it can make like staggering what we call very high quality heat.
We tend to keep thinking about de-carbonization um, and the climate crisis around making electricity. Electricity is like, at most a quarter of the problem. Like decarbonizing long range transportation, industrial heat processing, refining fuels, concrete, these things all have intense heat requirements. So what fusion has at its heart is that it doesn't just plug into the electrical infrastructure. It plugs into our energy infrastructure overall.
LHF: [00:08:13] We’ve mostly focused on electricity in this series, but if you’re making concrete or steel, what you need is a ton of raw heat, way more than electricity could provide. Right now, those kinds of factories use fossil fuels for that intense heat -- but fusion could deliver that.
Fusion power could also be dispatchable, which means it could be turned on and off exactly when we need it, unlike other forms of clean energy like wind and solar power.
DW: [00:08:48] It's an on demand energy source. You can control the, the amount of fuel in the, in the power output on the timescales of like seconds. You can turn it off in a fraction of a second.
LHF: [00:09:00] And then there’s the sheer amount of energy fusion can deliver. In fact, it’s so much energy that Prof. Whyte actually sees it as one of the challenges of getting the first fusion power plant out in the real world.
DW: [00:09:17] One of its limitations is that it has a minimum level of output of power, to make the star work. The minimum unit is probably like 50, a hundred million Watts of power, which is a lot of power. Like in the energy market that powers like a small city. So this, we'd have to build it at an enormous scale to get the very first one going.
LHF: [00:09:39] This is why people are so excited about the potential of fusion energy.
DW: [00:09:45] I don't think it's an exaggeration to say that economic fusion energy changes the world. It changes humanity's relationship to energy and how we use energy. Because it can be deployed into many of the present energy, energy systems and infrastructures. And it can be deployed anywhere on the planet in principle because you don't need the, you don't need particular access to a particular kind of fuel.
LHF: [00:10:09] All right, let’s come back down to Earth for a second. Affordable fusion energy doesn’t exist yet, and even Prof. Whyte can’t promise that it ever will. So why spend so much time talking about it?
Well, one of our main messages in this energy series is that no one energy source can get us to a carbon-free energy system on its own. We’ve heard scientists from all kinds of backgrounds tell us that we need many strategies together -- wind and solar along with energy storage and new power lines; energy efficiency; older technologies like nuclear and young ones like carbon capture and storage.
The potential of fusion shows us how much we could gain from also making investments in totally new energy technologies. And it’s not just fusion--other growing energy sources we haven’t had time to dig into, like hydrogen power, advanced biofuels, and concentrated solar power, which is totally different from the solar photovoltaics we covered in our episode on wind and solar. All of these could fill huge gaps in our ability to decarbonize our whole energy system, from electricity to transportation to the heat needed to make things like concrete and steel.
DW: [00:11:34] Decarbonizing our energy use is probably the hardest thing humanity will ever have to try. Changing how you make and interact with energy is at the heart of everything that we do, it's our entire way of life.
We need all hands on deck on all of the clean energy sources about getting there. And I really want to make sure fusion has a real fighting chance of being one of those.
LHF: [00:12:03] For more on fusion check out the MIT Energy Initiative’s podcast interview with Prof. Whyte, where he speaks more about commercializing fusion energy. We’ll also have other resources -- including an guide for educators to use this podcast in the classroom -- on our website, tilclimate.mit.edu
Thank you for tuning into Today I Learned: Climate, brought to you by the MIT Environmental Solutions Initiative. This was our last official episode in our second season, which we produced in collaboration with the MIT Energy Initiative.
I say that it’s our last official episode, because we may have a bonus episode -- or two -- up our sleeve. Just a heads up.
We’re now preparing for season three, so if there is a topic that you’d like us to cover, send us a tweet @tilclimate, or email us at firstname.lastname@example.org.
A shout out to our team, those who worked with us on our first two seasons:
Our student production assistants, Ruby Wincele, Cecilia Bolon, Darya Guettler, Olivia Burek and Skyler Jones.
Our graduate student writers, Jessie Hendricks and Rachel Fritts.
Aaron Krol, who did our show artwork and is a contributing writer.
Blue Dot Sessions created our music
The fabulous David Lishansky, our audio editor and producer.
I’m your host Laur Hesse Fisher.
I want to thank Prof. Dennis Whyte -- and all our experts for speaking with us for this season -- and thank you for listening.
For more episodes of TILclimate by the MIT Environmental Solutions Initiative, visit: tilclimate.mit.edu
For related energy podcasts from the MIT Energy Initiative, visit: http://energy.mit.edu/podcast/
For a MITEI podcast discussing fusion energy, visit: http://energy.mit.edu/podcast/game-changing-fusion/
To learn more Professor Whyte’s SPARC project, a compact, high-field, net fusion energy experiment, visit: https://www.psfc.mit.edu/sparc
Want to learn more about how fusion works in stars? Check out: https://sciencing.com/life-cycle-mediumsized-star-5490048.html
For information on the U.S. Department of Energy Fusion Energy Sciences (FES) program, visit: https://science.osti.gov/fes
In the episode, Professor Whyte talks about plasma in fusion reactions. Wondering what exactly plasma is? Check out: https://www.livescience.com/54652-plasma.html
- Why do you think fusion reactions can be sustained in stars but not in labs? What conditions might stars have that are difficult to replicate on Earth?
- In the episode, Professor Whyte talks about the advantage of fusion reactions creating high-quality heat. What are the advantages of an energy source that can provide raw heat, in addition to electricity?
- Not only would a fusion power plant provide high-quality heat, but it would provide it on a massive scale. Imagine a world where fusion is our main energy source. What might our energy, manufacturing, and transportation infrastructure look like? How might it be different from our infrastructure today?
- What are the steps of a fusion reaction? What happens in each step?
- Research and compare some fusion experiments happening in the world today. What are the goals of these different projects? What are the similarities and differences between them?
- Fusion reactions require heating hydrogen until it becomes a plasma. At what temperature does this happen? What different properties does hydrogen have in the gas phase and in the plasma phase?
- Fusion has the potential to generate much more energy than our current carbon-free energy technologies, but we don’t know when it will work on a commercial scale. Do you think we should count on fusion shaping our energy markets, or invest now in other carbon-free energy infrastructure?
- Demonstrate a fusion reaction using ping-pong balls:
- Use two different colors to label the balls as either protons or neutrons
- One student holds 1 proton and 1 neutron to form a deuterium atom
- One student holds 1 proton and 2 neutrons to form a tritium atom
- The rest of the class represents the heat and pressure needed to start the reaction. Have the class gather around the students representing the deuterium and tritium atoms, then move closer together until these two “atoms” collide.
- When the atoms collide, one student takes 2 protons and 2 neutrons to form a helium atom. Another student takes the remaining neutron.
- The students disperse as the reaction is completed, producing 1 helium atom, 1 neutron, and vast amounts of energy.
Open Teaching Materials
This course uses lectures and discussion to introduce the range of topics relevant to plasma physics and fusion engineering. An introductory discussion of the economic and ecological motivation for the development of fusion power is also presented. Contemporary magnetic confinement schemes, theoretical questions, and engineering considerations are presented by expert guest lecturers. Students enrolled in the course also tour the Plasma Science and Fusion Center experimental facilities.
This course provides an introduction to nuclear science and its engineering applications. It describes basic nuclear models, radioactivity, nuclear reactions, and kinematics; covers the interaction of ionizing radiation with matter, with an emphasis on radiation detection, radiation shielding, and radiation effects on human health; and presents energy systems based on fission and fusion nuclear reactions, as well as industrial and medical applications of nuclear science.
This course discusses MHD equilibria in cylindrical, toroidal, and noncircular tokamaks. It covers derivation of the basic MHD model from the Boltzmann equation, use of MHD equilibrium theory in poloidal field design, MHD stability theory including the Energy Principle, interchange instability, ballooning modes, second region of stability, and external kink modes. Emphasis is on discovering configurations capable of achieving good confinement at high beta.