Fusion power has this almost mythical appeal — unlimited clean energy, no carbon, no meltdowns. But a new study published in Nature Energy throws cold water on one of the central assumptions: that fusion will eventually be cheap.
The idea is simple. Technologies tend to get cheaper as we build more of them. Lithium-ion batteries dropped about 90% since 2013. Solar modules fell even faster. But not everything follows that curve. Nuclear fission, for example, has barely budged — its experience rate sits at a pathetic 2%.
What’s an experience rate? It’s the percentage by which costs drop every time cumulative installed capacity doubles. Solar: 23%. Onshore wind: 12%. Fission: 2%. Fusion, according to the researchers behind this study, will land somewhere between 2% and 8%.
That’s way below the 8% to 20% that most energy models currently assume. And it means fusion electricity could stay expensive for a long, long time.
The team, led by Lingxi Tang at ETH Zurich, interviewed fusion experts and asked them to rate the technology on three factors: unit size, design complexity, and need for customization. The pattern is clear — big, complex, custom stuff doesn’t get cheap fast. Fusion plants will be large, like coal or fission plants. They’ll be less customized than fission (fewer regulatory headaches), but far more complex than solar panels. Some experts literally said fusion complexity was off the scale the researchers provided.
None of this is surprising if you’ve been paying attention. Fusion reactors are engineering nightmares wrapped in plasma physics riddles. They require superconducting magnets, tritium breeding blankets, and containment systems that can handle temperatures hotter than the sun. You don’t just mass-produce those in a factory and ship them to a site.
So where does that leave the billions pouring into fusion? The US government allocated over $1 billion in fiscal 2024. Private investors added another $2.2 billion between July 2024 and July 2025. Tang himself asks the uncomfortable question: “If you’re talking about decarbonization of the energy system, is this really the best use of public money?”
I think he’s right to ask. Not because fusion is hopeless — it could still be a valuable part of the mix — but because the opportunity cost is real. That billion dollars could have bought a lot of solar panels, battery storage, or grid upgrades that work today.
Of course, predictions are hard, especially about the future. Egemen Kolemen from Princeton Plasma Physics Lab points out that in 2000, analysts thought solar would stay expensive. Then China scaled production and prices collapsed. “People weren’t exactly wrong then,” he says. “They were just extrapolating what they saw into the future.”
Fair point. Fusion could surprise us. Maybe a breakthrough in high-temperature superconductors or a novel confinement approach changes the game. Maybe China or someone else decides to go all-in on fusion the way they did with solar. But that’s a big maybe.
What the study does well is force us to confront our assumptions. Right now, many energy models assume fusion costs will drop like solar. That’s not just optimistic — it’s probably wrong. And when you’re making policy decisions worth billions, you should base them on realistic numbers, not wishful thinking.
I’ve been following fusion for years, and I’ve seen the hype cycles come and go. This study doesn’t kill fusion — it just reminds us that cheap energy isn’t a given. It has to be engineered, manufactured, and deployed at scale. And for fusion, that’s going to be harder than most people want to admit.
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