Maybe I missed it but it's not a net positive output. From the article, the implication it is:
"LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output"
From newscientist, the same info followed by a rider:
"generated a power output of 3.15 megajoules from a laser power output of 2.05 megajoules – a gain of around 150 per cent. However, this is far outweighed by the roughly 300 megajoules drawn from the electrical grid to power the lasers in the first place"
This was explained by another commenter yesterday, but this is not an issue. The 3.15:2.05 ratio is the news as it is the part that was difficult to achieve. The 300MJ accounts for significant laser inefficiencies in much the same way that the 3.15MJ of output won't convert to 3.15MJ of electricity as the conversion is not loss less.
In other words: it's a net-positive output for that reaction, not the whole process, there is still a lot of work to be done before you and I exchange comments on a server powered by fusion energy in homes powered by fusion energy.
> in much the same way that the 3.15MJ of output won't convert to 3.15MJ of electricity as the conversion is not loss less
...and very much touche! That's a good point. But I do feel the overall loss should have been made clear and distinct from the gain in one part of the whole. Gross vs net perhaps?
IIRC part of the issue is that NIF's lasers are very old and much less efficient than more modern ones. So the 300 MJ needed to power the lasers is higher than would be expected if this were commercialized.
"LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output"
From newscientist, the same info followed by a rider:
"generated a power output of 3.15 megajoules from a laser power output of 2.05 megajoules – a gain of around 150 per cent. However, this is far outweighed by the roughly 300 megajoules drawn from the electrical grid to power the lasers in the first place"