The encouraging part comes first: ignition is no longer a fluke. Researchers at America’s National Ignition Facility have now drawn more energy out of a fusion reaction than they poured in twice, and the second shot beat the first. After decades of work going back to the 1950s, these are the only two such results in history, and early findings suggest the physics holds up under repetition.
The setting is the Lawrence Livermore National Laboratory in California, where 192 lasers converge on a hohlraum, a small holder cradling a capsule of deuterium and tritium, both heavier forms of hydrogen. In December 2022 the experiment put out 3.15 megajoules, outdoing the 2.05 megajoules that drove it by 1.1 megajoules; the Financial Times initially relayed the pending result as 2.5 megajoules from 2.1 before confirmation. Then came July 30: an output above 3.5 megajoules, the Financial Times reported, the first repeat of the feat and a bigger yield than the debut.
The reaction from scientists has been unrestrained. Dr Robbie Scott, whose plasma physics group at the Science and Technology Facilities Council contributed to the work, called the December result a “momentous achievement”, adding that “Fusion has the potential to provide a near-limitless, safe, clean, source of carbon-free baseload energy” and that “The scale of the breakthrough for laser fusion research cannot be overstated”. Imperial College London’s Prof Jeremy Chittenden went further, calling it a “true breakthrough moment which is tremendously exciting”, proof that “the ‘holy grail’ of fusion, can indeed be achieved”.
The balance sheet tempers it. December’s surplus worked out to 0.4 MJ, about 0.1 kWh, roughly what it takes to boil a kettle. Chittenden’s caution: “We’ll also need to find a way to reproduce the same effect much more frequently and much more cheaply” before fusion becomes a source of power, alongside a long climb from demonstrating energy gain to “wall-plug efficiency where the energy coming from a fusion reactor exceeds its electrical energy input required to run the reactor”. A recent report in Energy Policy weighs in: the “yield would have to be much higher and the operation much quicker” to supply a grid. The method also leans on tritium, a radioactive isotope whose health effects are, in the view of Institute for Energy and Environmental Research president Arjun Makhijani, under-studied. Even with the new shots, competitiveness could be decades out.
Still, the direction is set, and it points forward. Each rung stands on the last: the 70% of laser energy recovered the year before, then ignition, then a stronger repeat. As Scott put it, “In order to transform NIF’s result into power production a lot of work remains, but this is a key step along the path”.
Sources
- Breakthrough in nuclear fusion could mean ‘near-limitless energy’ | Nuclear power | The Guardian
- US scientists trying to harness the power of the sun have made a 2nd major breakthrough for the future of sustainable, green energy | Business Insider Africa
