Jhe revelation that researchers had succeeded in creating a nuclear fusion reaction that generated more energy than it consumed was reassuring last week. For almost half a century I have reported on scientific matters and no decade has been complete without two or three announcements from scientists claiming that their work will soon allow science to recreate the processes that drive the sun. The end result would be the generation of clean, cheap nuclear fusion that would transform our lives.

Such announcements have been rare recently, so it gave me a warm glow to realize that standards could be returning to normal. By deploying an array of 192 lasers to bombard pellets of the hydrogen isotopes deuterium and tritium, researchers at the US National Ignition Facility (NIF) in Livermore, California, were able to generate temperatures found only in stars and thermonuclear bombs. The isotopes then fused into helium, releasing excess energy, they reported.

It was a landmark event but not a major one, though it didn’t stop the US government and swaths of the media around the world from indulging in a big hype around the lab’s accomplishments. The researchers had “overcome a major hurdle” to achieve the merger, the BBC said, while the the wall street journal described the achievement as a breakthrough that could herald an era of clean, cheap energy.

It is certainly true that nuclear fusion would have a beneficial impact on our planet by releasing large amounts of energy without generating high levels of carbon emissions and would be an indisputable boost in the fight against climate change.

The problem is that such visions have been presented to us many times before. In 1958, Sir John Cockcroft claimed that his Zeta fusion project would provide the world with “an inexhaustible supply of fuel”. This was not the case. In 1989, Martin Fleischmann and Stanley Pons announced that they had achieved fusion using simple laboratory equipment, a job that made world headlines but was never replicated.

To this list you can also add the International Thermonuclear Experimental Reactor (Iter), a huge facility under construction in Saint-Paul-lès-Durance in Provence, France, which was expected to achieve fusion by 2023 but has more than 10 years late. and tens of billions of dollars over budget.

In each case, the construction of the first commercially viable nuclear fusion power plants was predicted to be only a decade or two away and would transform our lives. These hopes never materialized and led to a weary cynicism spreading among hacks and scientists alike. As they joke now: “The merger is 30 years away – and always will be.”

It was strange that Jennifer Granholm, the US Secretary of Energy, claimed that the achievement of the NIF was “one of the most impressive scientific feats of the 21st century”. It’s a claim that’s hard to substantiate for a century that has already seen the discovery of the Higgs boson, the creation of Covid-19 vaccines, the launch of the James Webb Telescope and the deciphering of the human genome. By comparison, the ignition event at the NIF is second division stuff.

Most scientists have been cautious in their responses to the NIF’s “breakthrough” hype. They admit that a key step has been taken towards commercial fusion power, but insist that such plants remain distant goals. They should not be seen as likely saviors to get us out of the desperate energy crisis we currently face – despite all the claims that have been made in the past week.

Humanity has reached a point where its dire dependence on fossil fuels threatens to trigger a 2°C jump in global temperatures compared to our pre-industrial past. The consequences will be floods, fires, worsening storms, rising sea levels, the spread of disease and melting ice caps.

Here the scientists are clear. Fusion power won’t arrive in time to save the world. “We are still a long way from commercial fusion and that cannot help us deal with the climate crisis now,” said Aneeqa Khan, a nuclear fusion researcher at the University of Manchester. This view was supported by Tony Roulstone, a nuclear energy researcher at the University of Cambridge. “This NIF result is a success for science, but it’s still a long way from delivering useful and abundant clean energy.”

Currently, there are two main routes to nuclear fusion. One is to confine a burning hot plasma in a strong magnetic field. The Iter reactor follows such an approach. The other – adopted at the NIF facility – uses lasers to blast deuterium-tritium pellets, causing them to collapse and fuse into helium. In both cases, the reactions occur at more than 100 million C and involve major technological puzzles to control them.

Fusion therefore remains a long-term technology, even though many new investors and entrepreneurs – including Bill Gates and Jeff Bezos – have recently turned to the field, raising hopes that a new commercial impetus could reinvigorate the development of commercial factories.

This contribution is welcome, but let’s be categorical: fusion will not arrive in time to save the planet from climate change. Power plants powered by renewable sources or nuclear fission offer the only short-term alternatives to those that burn fossil fuels. We must base our hopes on these sources of energy. Fusion may gain its place later in the century, but it would be highly irresponsible to rely on a power source that will take at least another two decades to materialize – at best.