California researchers have successfully completed a nuclear fusion reaction that achieved “ignition”—or yielded more energy than was put into it—for only the second time in history, report Tom Wilson and Alice Hancock for the Financial Times. With this feat, the team has repeated their breakthrough results from an experiment in December.
Nuclear scientists say this is a key step toward producing clean and potentially cheap power—though they warn the fledgling form of energy still has a long way to go before it becomes a viable option.
“Since demonstrating fusion ignition for the first time at the National Ignition Facility (NIF) in December 2022, we have continued to perform experiments to study this exciting new scientific regime. In an experiment conducted on July 30, we repeated ignition at NIF,” a spokesperson from the Lawrence Livermore National Laboratory (LLNL) tells the Financial Times. “As is our standard practice, we plan on reporting those results at upcoming scientific conferences and in peer-reviewed publications.”
Nuclear power plants across the globe currently produce energy through a process called fission, which involves the splitting of an atom’s nucleus into two parts. While fission generates a substantial amount of energy with almost no greenhouse gas emissions, it also produces long-lived radioactive waste as a byproduct.
Scientists have long been aware of another process called fusion, in which two light nuclei combine together and release vast amounts of energy. Fusion is the reaction that powers the sun and other stars, and it has the potential to create enormous amounts of energy with less dangerous byproducts. But for decades, researchers have struggled to recreate and harness it.
Then, in December 2022, a team at LLNL in California announced they had, for the first time ever, created a fusion reaction with a net energy gain. Using 192 giant lasers, the team delivered 2.05 megajoules to their target, which subsequently released 3.15 megajoules of energy output.
Now, just eight months later, a spokesperson for the lab tells Reuters that the reaction has been repeated, and this time, it produced an even higher energy output.
“We are witnessing a moment in history: controlling the power source of the stars is the greatest technological challenge humanity has ever undertaken,” physicist Arthur Turrell tells Anthony Cuthbertson of the Independent. “This experimental result will electrify efforts to eventually power the planet with nuclear fusion—at a time when we’ve never needed a plentiful source of carbon-free energy more.”
Despite its benefits, however, nuclear fusion is likely not a silver bullet for climate change—researchers warn that it could be another few decades before fusion becomes a feasible energy source. Meanwhile, climate scientists have stated that to keep global warming to no more than 1.5 degrees Celsius, the world must reduce greenhouse gas emissions by 45 percent by 2030 and hit net zero emissions by 2050.
“If we stick at trying to do this through massive-scale projects, which take billions of dollars to construct and tens of years to develop, it could well be that fusion arises too late to have an impact on climate change,” Jeremy Chittenden, a physicist at Imperial College London, told New Scientist’s Matthew Sparkes in December. “What I believe we really need to do is to concentrate upon increasing the diversity of approaches so that we can try to find something that has a lower impact cost and a faster turnaround, so that we might be able to get something in ten or 15 years’ time.”