Stars have cores hot and dense enough to force atomic nuclei together, forming larger, heavier nuclei in a process known as fusion. In this process, the mass of the end products is slightly less than the mass of the initial atoms. But that “lost” mass doesn’t disappear — it’s converted to energy ... a lot of energy. So, can we harness this energy to power the world? George Zaidan investigates. This TED-Ed lesson was directed by Igor Ćorić, Artrake Studio, narrated by George Zaidan and the music is by Cem Misirlioglu and Brooks Ball.
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[00:00:00] Ted Audio Collective
[00:00:02] Nuclear fusion sounds like something out of a sci-fi novel.
[00:00:13] It's technology that promises to harness the power of the stars right here on Earth.
[00:00:18] But it's real. Scientists have been working on creating a miniature version of the sun's energy,
[00:00:24] using fusion to generate massive amounts of clean, nearly limitless power.
[00:00:30] The process is complex, but the goal is simple.
[00:00:33] To create a reactor that can power entire cities with minimal environmental impact.
[00:00:41] This is TED Tech, a podcast from the TED Audio Collective.
[00:00:46] I'm your host, Sherelle Dorsey.
[00:00:48] Today's TED-Ed lesson is all about, you guessed it, nuclear fusion.
[00:00:54] Imagine, two trucks of fusion fuel could replace the need for millions of tons of coal.
[00:01:01] Though we're still in the early stages, recent breakthroughs in ignition bring us closer to realizing this dream.
[00:01:09] Could fusion energy be the key to solving our energy crisis?
[00:01:13] Let's explore how this revolutionary technology might reshape our future.
[00:01:18] But before we dive in, a quick break to hear from our sponsors.
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[00:02:31] And don't forget to subscribe wherever you tune in.
[00:02:38] And now, listen to this TED-Ed episode, narrated by George Zayden.
[00:02:44] In the time it takes to snap your fingers, the sun releases enough energy to power our entire civilization for 4,500 years.
[00:02:52] So, naturally, scientists and engineers have been working to build a miniature star here on Earth to plug into our power grid.
[00:03:00] And the thing is, we already kind of have.
[00:03:04] It just doesn't look like a tiny star floating in a lab.
[00:03:07] Stars are made of an almost incomprehensible number of particles which gravity compresses into a super-dense core.
[00:03:14] This core is hot and dense enough to force atomic nuclei together, forming larger, heavier nuclei in a process known as fusion.
[00:03:23] The reverse process, where one atom splits into two, is called fission.
[00:03:28] In both processes, the mass of the end products is slightly less than the mass of the initial atoms.
[00:03:34] But that lost mass doesn't disappear.
[00:03:36] It's converted to energy according to Einstein's famous equation.
[00:03:40] And since C squared is such a massive number, both fission and fusion generate a lot of energy.
[00:03:47] Fusion in our sun mostly produces helium nuclei.
[00:03:51] In the most common pathway, two protons fuse to form a deuterium nucleus,
[00:03:55] which then fuses with another proton to form a helium-3 nucleus,
[00:04:00] which then fuses with another helium-3 nucleus to form a helium-4 nucleus.
[00:04:05] But there's a catch.
[00:04:06] That first step is incredibly rare.
[00:04:09] Only one in a hundred septillion collisions between protons results in a deuterium nucleus.
[00:04:15] In the sun, this isn't a problem because there are so many protons that even a reaction this rare happens all the time.
[00:04:22] But on Earth, researchers rely on a more easily reproducible reaction,
[00:04:27] where a deuterium nucleus fuses with a tritium nucleus to form a helium-4 nucleus and a neutron.
[00:04:33] We've actually been doing reactions like this one inside particle accelerators since the 1930s.
[00:04:40] But these accelerators are not designed to harness the energy this reaction releases.
[00:04:44] Rather, they're used to generate neutrons for a variety of scientific and military purposes.
[00:04:49] Whereas, if we want to use fusion to produce limitless energy,
[00:04:53] we'd need a device that can harness the energy released,
[00:04:56] channel enough of that energy back into the device to keep the reaction going,
[00:05:00] and then send the rest out to our power grid.
[00:05:03] And for that job, we need a nuclear fusion reactor.
[00:05:07] Like a particle accelerator, a reactor would generate helium nuclei and neutrons.
[00:05:12] But that reaction would happen in a super-hot core,
[00:05:15] and the resulting neutrons would shoot outward to heat up a layer of lithium metal.
[00:05:20] That heat would then boil water, generating steam to run turbines and produce electricity.
[00:05:25] Meanwhile, the helium nuclei would stay in the core
[00:05:28] and slam into other nuclei to keep the reaction going and the electricity flowing.
[00:05:33] This tech has many practical challenges,
[00:05:36] including how to confine a swirling mass of million-degree matter.
[00:05:40] But the biggest hurdle is achieving what's called ignition.
[00:05:43] An energy technology is only commercially viable if it puts out more energy than it uses,
[00:05:48] and a fusion reactor needs a lot of energy to get the core hot enough for fusion to occur.
[00:05:54] So there's a tipping point,
[00:05:55] a moment when the fuel is hot enough to start the reaction
[00:05:58] and release more energy than is needed to reach and maintain that temperature.
[00:06:03] This is ignition.
[00:06:05] Stars reach ignition under the force of huge amounts of gravity,
[00:06:08] but this approach is impossible on Earth
[00:06:10] since you'd need thousands of times the mass of, well, the entire Earth.
[00:06:15] So researchers typically rely on vast arrays of lasers
[00:06:18] or methods that combine magnets with high-energy particles
[00:06:22] or electromagnetic waves similar to those in your microwave oven.
[00:06:26] In 2022, scientists at the U.S. National Ignition Facility
[00:06:30] demonstrated ignition for the first time ever,
[00:06:33] using 192 lasers to heat deuterium and tritium to 100 million degrees.
[00:06:40] While this was a huge step forward,
[00:06:42] we're still a ways off from a self-sustaining,
[00:06:44] long-running reactor that produces more energy than it uses.
[00:06:48] But once operational,
[00:06:49] these relatively small reactors could power a city of a million people for a year
[00:06:54] with just two pickup trucks of fuel.
[00:06:56] Today, you'd have to burn roughly 3 million tons of coal
[00:07:00] to produce that much energy.
[00:07:02] That is the promise of fusion,
[00:07:05] limitless, on-demand energy with almost no emissions.
[00:07:09] True star power right here on Earth.
[00:07:11] And that's it for today.
[00:07:24] TED Tech is part of the TED Audio Collective.
[00:07:27] This episode was produced by Nina Bird Lawrence,
[00:07:30] edited by Alejandra Salazar,
[00:07:32] and fact-checked by Julia Dickerson.
[00:07:34] Special thanks to Maria Latias,
[00:07:36] Fer de Grange,
[00:07:37] Daniela Belarezo,
[00:07:38] and Roxanne Highlash.
[00:07:40] I'm Cheryl Dorsey.
[00:07:42] Thanks for listening.