FOR the first time on Earth, a controlled fusion reaction has generated more power than was used to kickstart it. Reaching the milestone provides real hope that fusion reactors can deliver on the decades-long promise of abundant, clean energy that, according to the Atomic Energy Commission in 1954, will be 鈥渢oo cheap to meter鈥�.
With 100 years of science behind the result and decades of engineering still ahead, fusion will be 鈥� if we get there 鈥� perhaps the best example of coordinated, long-term effort by humans and the greatest pay-off ever received. The engineers who construct the first commercial reactors probably haven鈥檛 been born.
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On 5 December, the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in California fired up: 192 of the world鈥檚 most powerful lasers compressed a tiny capsule of fuel, kickstarting a reaction that replicated the one at the heart of our sun.
NIF鈥檚 lasers drew, for a few billionths of a second, 500 trillion watts 鈥� more than the output of the entire US national grid. The diamond-shelled fuel capsule they targeted is made to be 100 times smoother than a standard mirror because imperfections the size of a bacteria can stymie the reaction.
The lasers put out just over 2 megajoules of power, but the reaction provided 3.15 megajoules. This tiny energy gain would barely heat a bath, and the lasers drew 300 megajoules from the grid to run, but the significance was far greater: fusion power became not just theoretically possible, but demonstrably so.
Fusion is a perfect example of what UK Astronomer Royal Martin Rees calls , the idea that multiple generations of coordinated effort are needed to solve science鈥檚 grand challenges, just like the stonemasons who worked on Ely Cathedral in southern England, knowing they would never see it complete.
As LLNL director Kim Budil said, announcing the news, it took generations of engineers and scientists to get here. 鈥淭his is how we do really big, hard things.鈥�
You can trace these results back more than a century to Francis William Aston鈥檚 discovery that four hydrogen atoms are heavier than a single helium atom, implying that if you combine the former into the latter, there is some mass unaccounted for that can be turned into energy. It is this process we are now learning to tame, thanks to the work of scientists from almost every corner of academia.
Ironically, for a technology that has the potential to avert global catastrophe, NIF was borne out of the US nuclear weapons programme, originally intended 鈥� and still used 鈥� as a way to recreate the conditions inside the nuclear bombs that anti-testing treaties mean can no longer be detonated.
Experts are divided on how far off fusion power is. But the old joke that it is 30 years away, and always will be, could be losing relevance. And while it would be foolhardy to pin all our hopes on fusion solving climate change, it represents a huge opportunity.
There are big challenges ahead, for NIF and alternative designs such as the JET and ITER tokamak reactors. To realise commercial fusion energy with a design like NIF, you have to do a lot of things that are currently impossible. At the moment, the experiment fires once, for a few billionths of a second, then takes hours to cool. A viable reactor needs to ignite constantly, reliably and for long periods without maintenance. How we achieve that isn鈥檛 obvious.
But construction on NIF started in 1997 and the technology dates back to the 80s and 90s. There is good reason to believe that improvements are available. Time will tell which reactor design will be the first to go into commercial production, but when it does, the designers will be standing on the shoulders of many thousands of scientists and engineers.
Matthew Sparkes is a reporter at 快猫短视频. @Sparkes
