Fusion, the holy grail of the energy transition, is closer than ever before. But it’s still unclear whether it can be commercialised in time to ward off the climate crisis.

Earlier this month, a ‘tokamak’ fusion reactor in the UK was announced to have set a global record for the amount of power created. The experiment had occurred in December.

Tokamak is the most mature of fusion technologies, and has been seen as a good contender to be the first technology to be commercialised.

The running joke amongst scientists still is that fusion – which creates no greenhouse gas (GHG) emissions and no long-term radioactive waste – is always 30 years from being ready to make a sizeable contribution to human energy needs despite seven decades of research.

The first tokamak rector was in the 1950s in the Soviet Union, so the technology is hardly new.

In fusion’s favour, as opposed to the fission that is today’s nuclear power, is that the radioactive waste created has a short half-life. Fusion creates larger atoms from smaller ones, whereas fission smashes atoms apart.

Most recently, researchers at the Joint European Torus (JET), an experimental tokamak fusion reactor at the Culham Centre for Fusion Energy in Oxfordshire in the UK, were able to generate 69 megajoules of energy over a period of 5.2 seconds from 0.2 milligrams of tritium and deuterium fuel. It was a world record for fusion energy output.

It was no mean feat, and the stats give an idea of why commercialised fusion is some distance off. When operating, the JET reactor is the hottest point of the entire solar system, reaching 150mn degrees Celsius (270mn °F), or more than 10 times as hot as the centre of the sun.

The energy output at JET equalled 16.5kg of TNT – from just the 0.2 milligrams of fuel. It was equivalent to a power output of 12.5 MW, enough to electrify 12,000 homes, said officials at a press conference, reported New Scientist.

This is significant, since one kilogram of fusion fuel contains about 10mn times more energy than a kilo of coal, oil or gas, noted the Guardian.

But still, the experiment operated at a net energy loss, given how much the fuels had to be heated. JET has operated since 1983, and is now being closed down over a period of 17 years.

The JET reactor used strong magnetic fields to shape ‘plasmas’, a superheated ionised gas, into the reactor’s shape, a doughnut. The extreme heat brought about fusion reactions so that nuclei bound together to form new atomic elements while releasing huge amounts of energy.

At JET, the resulting gas was helium, an inert gas that does not burn or react with other elements. This is much like how the sun produces its energy.

“JET has operated as close to powerplant conditions as is possible with today’s facilities and its legacy will be pervasive in all future power plants. It has a critical role in bringing us closer to a safe and sustainable future,” said Professor Ian Chapman, chief executive of the UK Atomic Energy Authority, in a statement.

Instead, the UK’s fusion programme will include the Spherical Tokamak for Energy Production (STEP), a facility that will be constructed by 2040 in Nottinghamshire to demonstrate – hopefully – the ability to use fusion energy to generate electricity for the UK grid, said government officials.

Fusion has been in the news. In August of 2023, for the second time scientists at the Lawrence Livermore National Laboratory in California announced an experiment that created more energy from fusion that was used. It was a so-called net energy gain, though only enough heat was created for a bathtub of water.

The research, at the National Ignition Facility (NIF) on July 30, was a world first, yielding even higher energy output compared with the lab’s the previous experiment in December. Most recently, the NIF released almost twice the energy put in. The experiment, which was not tokamak, instead used lasers.

Then at COP28 the US unveiled the first global strategy to commercialise fusion power. The US Special Envoy on Climate Change, John Kerry, unveiled the strategy in Dubai.

And in late December, China announced the Controllable Nuclear Fusion Innovation Consortium, which the Asian country hopes will allow it to win the race for scaled-up fusion energy.

Indeed, a breakthrough in producing power by fusion reactions is expected this year, according to S&P Global. That may occur. Helion, of Washington State, the world’s first private fusion company to reach 100mn-degree plasma temperatures with its sixth fusion prototype, expects to demonstrate the ability to produce electricity in 2024 with its seventh prototype.

It might seem like just another scientific experiment but Helion has a rare power purchase agreement (PPA) to provide power to tech giant Microsoft, the world’s first fusion PPA. Helion’s plant, to be sited in the US – the location has not been disclosed – is due to come online by 2028 and will generate 50 MW after a one-year ramp-up.

Helion’s process uses deuterium and helium-3, hence the company’s name. To create fusion, in a plasma accelerator, Helion raises fusion fuel to 100mn degrees Celsius and directly extracts electricity with a high-efficiency pulsed approach.