Every few years, the world’s biggest fusion project holds a press conference to announce a new date. The tone is always the same: confident, forward-looking, a little relieved that the uncertainty has finally been resolved. Nobody dwells on what the last date promised.
ITER’s original baseline, set in 2016, promised first plasma by 2025. In 2024, the project announced a new one: operation now starts in 2034, and deuterium-tritium fusion — the step that actually matters, the one where the reaction produces more energy than it consumes — has moved from 2035 to 2039. Roughly €5 billion has been added to the cost. That’s a nine-year slip in the reactor’s operational date, arrived at over eight years, on the largest, best-funded, most internationally scrutinised fusion project that has ever been built. It isn’t even the project’s first upward revision: the project’s own cost estimate climbed from roughly €10 billion when its design was finalised in the late 1990s to around €15 billion by 2010, before the 2024 rebaseline added the latest €5 billion on top.
And 2026 has produced the most confident wave of fusion dates in years.
What’s actually different this time
This isn’t vapourware. The US Department of Energy finalised a national Fusion Science and Technology Roadmap in June 2026, targeting commercial pilot plants in the mid-2030s. Commonwealth Fusion Systems’ SPARC project entered assembly and commissioning in 2026 and is installing its ring of 18 D-shaped superconducting magnets, targeting first plasma in 2027. Global private fusion investment has passed $14 billion, according to the Fusion Industry Association’s 2026 survey. In the UK, the STEP programme has appointed the Ilios consortium as construction partner under an initial £200 million contract, with future programme opportunities valued at up to £10 billion, for a site at West Burton in Nottinghamshire; construction is due to begin in the early 2030s, with a commercially viable plant targeted for 2040.
That’s real capital, real hardware, and real engineering progress. SPARC’s magnet programme is a working demonstration of the compact, high-field superconducting technology that makes a smaller, cheaper tokamak possible at all: the magnets are physically being installed in the reactor now. Fusion is not fake, and the physics keeps getting easier to demonstrate.
What the history says about the newest date
The “fusion is thirty years away” line has been a joke in the field since the 1970s, and it’s a measured pattern, not just a punchline. The US Magnetic Fusion Energy Engineering Act of 1980 called for a $20 billion, twenty-year effort to build a demonstration plant by the end of the century. It didn’t happen. A May 2023 literature review in the Journal of Fusion Energy, tracking four decades of expert estimates, found that twenty years ago experts put commercial fusion at 28.3 years away. The equivalent estimate today is 17.8 years away — real progress, on one measure, but still a moving target rather than an arrival date.
No commercial fusion plant has ever put electricity onto a grid. Fusion’s contribution to electricity generation crossing 1% of total supply is more plausibly sometime in the 2040s, not the mid-2030s the boldest current claims suggest.
The pattern underneath all of this is structural, not a matter of any one project’s competence: fusion megaprojects run on multinational funding and multi-decade construction, which makes admitting a delay politically and financially costly, and quietly resetting the baseline comparatively cheap. Each reset gets reported as the project staying on track against its new date, not as one more confirmation of the pattern. There’s no independent, standard mechanism that checks a new fusion timeline against the sector’s own history of missing its stated decade before public money is committed on the strength of it.
The people actually on the hook for these dates aren’t the physicists. They’re the taxpayers and ratepayers funding STEP’s construction contracts, and the communities living near the sites being built now — West Burton in Nottinghamshire, or Chesterfield County, Virginia, near Richmond, where Commonwealth Fusion has proposed its planned ARC plant. All of them are committed to multi-decade infrastructure on the basis of dates that the sector’s own fifty-year history suggests are unlikely to hold as stated.
My Opinion
I’m not arguing against fusion. We need to be investigating every serious option for the future of power generation, and fusion has earned its place on that list. What I don’t accept is treating any of these timelines as something you can build energy policy around. The current emphasis sits heavily on renewables, and renewables alone don’t match the way we actually consume and demand energy — intermittent by nature, feeding a grid that needs to deliver on demand, all day, every day. Fusion, and everything else genuinely capable of dispatchable power, deserves serious investment now — on the honest understanding that nobody yet knows when any of it actually lands.
The UK has just signed up a construction partner for STEP against a 2040 target, on a programme whose full cost could run past £10 billion, on a technology whose most recent, most public precedent moved its own operational date by nine years in eight. That doesn’t make fusion fake, but it does make the newest date exactly as reliable as the last one — and the last one was wrong by nearly a decade. What would it take for a fusion timeline to be reported against its sector’s own track record, rather than as though this is the first one that’s ever been made?
You’re reading The Next Evolution by Neil Catton, articles that explore the human world and the intersection of technology, they try and ask difficult questions - not to scare - but to inform. If someone forwarded this to you, you can subscribe free at neilcatton.substack.com.
Neil Catton is the author of The Next Evolution, The Cognitive Crucible and The Shadow System - available on Amazon, and writes at the intersection of technology, ethics, and human purpose.