Researchers claimed a “watershed moment” in the development of nuclear fusion technology with the successful test of a powerful magnet that is said to hold the key to future generation of unlimited zero-carbon energy.

Partners Commonwealth Fusion Systems (CFS) and the Massachusetts Institute of Technology (MIT) claimed the creation of a record-breaking magnetic field for the first time “opens a clear path” to fusion power, which is hailed by some as the holy grail of clean energy but seen by others as a distraction from proven green technologies such as wind and solar.

Technology start-up CFS – which is backed by investors including Bill Gates, and fossil energy giants Eni and Equinor – said they successfully created a magnetic field of 20 tesla, the most powerful yet of its type using high temperature superconducting (HTS) magnet technology that will sit at the heart of planned nuclear fusion systems.

The sustained magnetic field is powerful enough to achieve the fundamental aim of a nuclear fusion system – to achieve ‘net energy’, producing more than it consumes – according to the project team.

Dennis Whyte, director of MIT’s Plasma Science and Fusion Center and professor of engineering, said the 5 September test answers a key question over the viability of the small-scale tokomak devices being developed by CFS, which are claimed to offer the fastest practical route to making fusion a reality.

“It’s really a watershed moment, I believe, in fusion science and technology,” said Whyte, adding that fusion would be “an inexhaustible, carbon-free source of energy that you can deploy anywhere and at any time. It's really a fundamentally new energy source”.

CFS chief executive Bob Mumgaard claimed: “This record-breaking magnet is the culmination of the last three years of work and will give the world a clear path to fusion power for the first time.”

The CFS/MIT team said the scientific milestone keeps the project on course to demonstrate net energy from fusion by 2025, followed by commercial-scale devices that generate thermal energy that could be harnessed to produce power in a conventional steam cycle.

Mumgaard told Recharge in a 2020 interview that fusion could play a vital role in the energy transition by “filling the gaps” left by wind and solar.

However, he admitted that even if the first commercial systems appear in the early 2030s, deployment of commercial fusion at gigawatt scale won’t happen “until the latter half of the 30s at the earliest”.

But Mumgaard claimed that does not undermine the case for the technology. He told Recharge: “If you look at other technologies and markets, and what’s needed, that’s in the range where you’re at the time where problems are getting really hard on carbon emissions, because you’ve taken all the easy gains.”

Nuclear fusion researchers are eager to distinguish it from its cousin technology nuclear fission, hailing its potential to deliver unlimited zero-carbon energy by fusing atoms, a process that’s said to be free of the risks of fission, which splits atoms apart.

But despite the buzz around the technology, the sheer difficulty of the physics involved has made research in the field the subject of a standing joke that “fusion is always 40 years away”.

There is also almost no visibility over the cost of energy produced by fusion, and many argue that the massive falls in wind and solar power prices, allied with storage technologies, smart networks and the massive potential of green hydrogen, will make fusion economically unviable before it is even born.

Nuclear fusion - star power on earth

Nuclear fusion energy aims to harness the reactions that power the sun to produce unlimited, on-demand, clean energy.

The process involves changing a gas to a plasma at temperatures of tens of millions of degrees, often aided by superconducting magnets, to create collisions between hydrogen atoms, tapping the energy that’s produced.

Unlike its close cousin nuclear fission – basis of the current global nuclear industry, which relies on splitting rather than combining atoms – fusion is said by scientists to present no risk of the sort of runaway reaction that led to the Chernobyl disaster.

And while it is not waste-free, the by-products are said to be low and short-lived compared to fission, and much more easily manageable.

Almost every major economy is involved in a project that aims to crack fusion energy, with the largest example the ITER project in France that's backed by 35 nations.

But with the most ambitious projects not due to even start experiments until 2040 or 2050, it is questionable whether they will be in time to make any impact on climate change – assuming they work at all.