Nuclear fusion—it’s the energy of the stars, the cosmic flame that powers the sun, and, if we could just figure out how to bottle it, it could be the ultimate solution to our energy problems. Clean, limitless power that doesn’t pump CO₂ into the atmosphere sounds like science fiction. But we’re working on it. And by “we,” I mean thousands of scientists in dozens of countries spending decades trying to achieve what the universe does naturally: smashing atoms together to create energy.
Sounds simple, right? Except it’s absurdly, almost laughably difficult. Let’s break it down.
The Insanely Hard Road to Fusion
First, a reality check. To achieve fusion, you need to heat a gas of hydrogen atoms to over 150 million degrees Celsius. That’s more than ten times hotter than the core of the sun and hotter than just about anything else in the universe—including the quasar 3C273, which reaches a scorching 100 billion degrees. So, we’re not just building a tiny star on Earth—we’re building the hottest spot in the known universe. And it’s not just about reaching those temperatures. Containing that plasma, which turns into a swirling, chaotic soup of positively charged nuclei and negatively charged electrons, is an entirely different level of insanity. You can’t let it touch anything solid, or everything melts. That’s why ITER is essentially a €50 billion experiment in magnetic wizardry.
ITER: Probably Humanity’s Wildest Science Experiment
ITER, being built in southern France, is the world’s most ambitious science project, involving 35 countries and aiming to create fusion power on Earth for the first time. The reactor’s design—a tokamak—relies on powerful magnetic fields to confine this ultra-hot plasma, keeping it from vaporizing everything it touches. The precision required here is almost unimaginable: those magnetic fields need to be millimeter-perfect to keep the plasma stable while operating under conditions that no other place on Earth (or in the universe) endures.
Yet, there’s growing debate. Some experts argue that the stellarator, an alternative reactor design, could be superior to the tokamak. Stellarators like Wendelstein 7-X in Germany have shown better potential for stable plasma confinement, without needing the continuous electrical current that tokamaks require. If they’re right, ITER’s billions may have been bet on the wrong horse. Stellarators are insanely complex to build, but many believe they could be the long-term solution for fusion energy.
Deuterium, Tritium, and the Tritium Dilemma
Fusion’s favorite fuel is deuterium and tritium, both isotopes of hydrogen. Deuterium is easy to find—one in every 5,000 hydrogen atoms in seawater is deuterium. Tritium, on the other hand, is a rare, radioactive isotope that doesn’t exist in significant quantities on Earth. Right now, we get it from nuclear fission reactors, but that’s not scalable.
The solution? Not there. The current approach? Lithium-6, an isotope of lithium: when hit with neutrons, lithium-6 can “breed” tritium within the reactor itself. This is why future fusion reactors will have lithium linings to ensure their own fuel supply. The problem is that lithium-6 is relatively scarce, and as fusion scales up, demand for this isotope could spike.
Magnetic Fields: Holding the Sun in Place
To keep plasma from touching the reactor walls, tokamaks use superconducting magnets that generate fields up to 12 teslas—250,000 times stronger than Earth’s magnetic field. These magnets are cooled to -269°C, while inside, the plasma blazes at 100 million degrees. Even with this technology, stability is elusive—containing that plasma for more than a few seconds is an achievement in itself.
Laser-Based Fusion: The Startup Gamble
While ITER bets big on tokamaks, laser-based fusion is gaining traction, especially among startups. Instead of magnetic confinement, laser fusion uses inertial confinement: lasers fire at a tiny fuel pellet, compressing it to the point of fusion.
The National Ignition Facility (NIF) recently achieved “ignition,” where more energy was generated from the fusion reaction than was absorbed by the fuel. But here’s the catch—while the fuel ignited, the energy required to power the lasers still far exceeded the energy produced.
Unlike the massive, international ITER, laser fusion is being driven by startups, thanks to its more agile development cycle. Many of those are pioneering various approaches, focusing on smaller, cheaper reactors. Their speed and flexibility make them a hotbed for innovation, even though significant hurdles—like the enormous energy demands of the lasers—remain.
Other Fusion Fuels: Beyond Deuterium and Tritium
While deuterium and tritium are the top choices for fusion, other elements could, in theory, be used. Helium-3 is one alternative often touted as the dream fuel—no radioactive waste, and it’s safer. The problem? Helium-3 is extraordinarily rare on Earth and would likely need to be mined from the moon, making it a bit impractical for the time being. Proton-boron fusion is another cleaner option but requires even higher temperatures than deuterium-tritium reactions, making it a technological moonshot.
Fusion vs. the Sun
Fusion on Earth is like trying to recreate the sun’s processes without the sun’s help. In the sun, fusion happens at relatively “low” temperatures (15 million degrees) thanks to its immense gravitational pressure. Here, without that pressure, we need to crank the heat up to 150 million degrees to achieve fusion. And we’re trying to do this in reactors smaller than a football field, while the sun is a cosmic behemoth 1.3 million times the size of Earth.
The Road Ahead
Fusion milestones are being reached, but the road ahead is long. ITER won’t conduct full-scale fusion experiments until the 2030s, and even with the excitement around laser fusion, commercial viability remains distant. But the momentum is building. Fusion is the holy grail of energy: clean, virtually limitless, and potentially game-changing. It’s hard, yes—ridiculously hard—but every new breakthrough brings us one step closer to bottling the power of the stars.