A fusion reaction has never produced more energy than was put in
The old claim turned out to be wrong and was rejected by evidence.
TaughtFusion is the power source of the future and always will be. Every experiment consumes far more energy than the reaction gives back, and breakeven, getting out as much as you put in, has never been reached.
NowOn 5 December 2022 the National Ignition Facility reached ignition: 2.05 megajoules of laser energy delivered to the target produced 3.15 megajoules of fusion energy. It was the first time a controlled fusion reaction returned more energy than was delivered to it.
What actually happened
The milestone is real and it is narrow, and both halves of that sentence matter.
Inside the target chamber, 192 laser beams delivered 2.05 megajoules to a peppercorn-sized capsule of hydrogen fuel, and the reactions released about 3.15 megajoules, roughly one and a half times as much. That ratio, output over the energy delivered to the fuel, is scientific breakeven, a line physicists had chased since the 1950s and never crossed in a laboratory.
The caveat is the one the headlines skipped. Producing those 2.05 megajoules of laser light drew roughly 300 megajoules from the wall, because the lasers are wildly inefficient. Measured end to end, the shot returned about one percent of what the facility consumed. So this is not a power plant, the reaction happens once and briefly, and nobody at Livermore claims otherwise. What changed is a single stubborn word: for the first time, a fusion reaction gave back more than was delivered to light it.
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Who was taught this
Still standard through 2022, so anyone who finished school between 1950 and 2022 learned the earlier version.