Scientific vs engineering breakeven
NIF passed scientific breakeven in 2022 — but the lasers drew ~300 MJ from the wall to deliver 2 MJ to the target. Engineering breakeven, where the whole plant nets energy, is the bar that matters for the grid.
In December 2022 the National Ignition Facility crossed scientific breakeven: its fuel released more energy than the laser light delivered to it. It was a genuine physics milestone — the first controlled fusion to return a net gain at the target.
The catch is what “delivered to it” leaves out. NIF's lasers needed on the order of 300 MJ from the grid to put about 2 MJ onto the target, which then produced a few MJ of fusion. Engineering breakeven — where the entire plant makes more electricity than it consumes — is a much higher bar, and it is the one that matters for putting power on the grid.
Scientific breakeven proves the fuel can win; engineering breakeven proves the machine can. Keeping the two separate is essential to reading fusion news honestly: a record gain at the target is real progress, but it is not the same as a reactor that would light a single home.