this post was submitted on 06 Feb 2024
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[–] [email protected] 263 points 9 months ago (5 children)

Excluding all the ancillary services, including the lasers that maintained the plasma, which was the principle part of this latest test.

Factoring everything in, they're at about 15% return.

This is still very good for this stage, but the publications are grossly misleading.

[–] [email protected] 22 points 9 months ago

The publications are not misleading, just these headlines.

[–] [email protected] 97 points 9 months ago (1 children)

I want to add that experimental reactors used for scientific research might never become net energy positive and that would be fine. Their purpose isn't to generate profit, it's to learn more about the physics, so it will be more valuable for them to be adaptable than efficient.

However, that doesn't mean that you can't take a configuration that has been shown to have potential and make a reactor that is more efficient than adaptable and use that to generate power for the electrical grid.

Basically, they have two different purposes.

[–] [email protected] 48 points 9 months ago

Absolutely. Also, the fact that the reactor was only running for a short time plays a part. Usually there is a significant energy cost in starting and stopping, which is offset by running for a long time. However, these reactors are not designed for continued running.

It's all a process of development, and even though the article is perhaps a little sensationalist, they're making good progress.

[–] [email protected] 9 points 9 months ago (1 children)

That's what I came to the comments to find. Thank you. Would have been much bigger news if it was net energy positive.

[–] [email protected] 8 points 9 months ago (2 children)

15% return is still net energy positive isn't it? Or is that not 15% above the input?

[–] [email protected] 3 points 9 months ago (1 children)

From another article: "In an experiment on 5 December, the lab’s National Ignition Facility (NIF) fusion reactor 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."

https://www.newscientist.com/article/2350965-nuclear-fusion-researchers-have-achieved-historic-energy-milestone/

[–] [email protected] 1 points 9 months ago (2 children)

That's worded strangely (powering the lasers takes both 300 and 2.05 megajoules?) but oof

[–] [email protected] 3 points 9 months ago* (last edited 9 months ago)

Energy can be measured as occurring in different physical phenomena. There is energy in sound waves/packets, energy in light waves/packets, energy in matter, etc.

The 300 MJ number refers to the electrical energy in the form of electromagnetic fields carried specifically through solid conductors via electron movement along the conductors.

The 2.05 MJ number refers to the radiative energy in the form of electromagnetic fields sent specifically through free space/a vacuum (I presume; I didn't read the article, so maybe the laser medium was a vacuum or something else) via photons/waves. No electrons, aside from those in the lasers that create the photons in the first place.

So there is a conversion from electric to radiative energy here.

Start Edit:

And as another commenter said, in this conversion there are losses because materials aren't perfect.

:End Edit

If the 3 MJ radiant energy from the nuclear material was then converted back into electric energy via steam processes, we'd get a comparable number compared to the 300 one.

This is also why you see nuclear/CSP plants quoted in MWt and MWe: there is a conversion that takes place from thermal energy (vibrations of atoms/compounds) into electric energy.

[–] [email protected] 4 points 9 months ago

Powering the laser takes 300 MJ but the actual laser power (the energy in the light) is only 2.05 MJ. The rest of the energy is lost to heat and other inefficiencies. If the laser could be created with 100% efficiency then the input energy would also be 2.05 MJ.

[–] [email protected] 3 points 9 months ago* (last edited 9 months ago) (2 children)

I can't read the full article (paywalled for me) but it references the National Ignition Facility so the way it goes is super lasers blast a tiny hydrogen thing and that creates a tiny bit of fusion that releases the energy. The energy of the laser blast is what's being called the input and the fusion energy released the output. What is misleading is that a greater amount of energy was used create the laser blast than the laser blast itself outputs. If you consider the energy that went into creating the laser blast the input (rather than the laser blast itself), then it's usually not a net positive energy release.

[–] [email protected] 2 points 9 months ago
[–] [email protected] 2 points 9 months ago (2 children)

What other energy are you referring to? Like warming up the laser?

[–] [email protected] 2 points 9 months ago (1 children)

[email protected] got it, but basically lasers are pretty inefficient. The article I just found said (in a different run of this facility) they put 400MJ into the laser to get 2.5MJ out of it. So that makes the whole firing system what, 0.6% efficient? Your fusion reaction would have to give more than 400MJ to truly be in the positive for this particular setup/method, but again this facility is a research one and not meant to generate power - there isn't even a way to harness/collect it here.

[–] [email protected] 2 points 9 months ago

Oh so the laser's generating mostly heat and a little coherent radiation, and they're only referring to the coherent radiation as the "energy input" to the process.

Hmm. Kinda sketch.

Especially because that's not trivial. If we have no way of obtaining laser light other than that process, and the laser is the only way to feed the fusion reactor, then that's 100% on the balance books of this process.

[–] [email protected] 3 points 9 months ago

Remember when incandescent light bulbs were the norm? They worked by sending full line voltage through a tiny tungsten wire that would get so hot that it glows, making some light, but 95% of the energy that gets consumed is frittered away as heat? The high-power lasers needed to make fusion happen are a lot like that.

I believe all this article is saying is that 15% more energy than what came out of the lasers as useful laser light was liberated in the reaction.This completely ignores the energy it took to power those massively inefficient lasers.

I think it also ignores the fact that the 15% more energy liberated wasn't actually, like, harnessed by a generator. I believe (and I may be wrong) this was testing only the reaction itself. Actually hooking that up to a turbine and using it to create energy that is cost competitive with contemporary sources is still a completely unsolved problem.

[–] [email protected] 47 points 9 months ago (1 children)

but the publications are grossly misleading.

I think you're only referencing the headline, the article itself clearly states what you said

[–] [email protected] 8 points 9 months ago (5 children)

Is the headline not part of an article?

[–] [email protected] 7 points 9 months ago (1 children)

When I see "publication" I assume it's the actual scientific paper and not the article reporting on said paper.

[–] [email protected] 5 points 9 months ago

That's a great point. I absolutely agree with you on that.

[–] [email protected] 7 points 9 months ago* (last edited 9 months ago)

It's easier to nitpick than it is to interact with the actual argument.

I agree with you. The headline is misleading, and I think it devalues the article.

[–] [email protected] 11 points 9 months ago

What was your question? I only read "is the" and thought I could base my response off of only that.

[–] [email protected] -2 points 9 months ago (1 children)
[–] [email protected] 4 points 9 months ago
[–] [email protected] 15 points 9 months ago (3 children)

When one says a publication is grossly misleading, it certainly implies the entire publication

[–] [email protected] 5 points 9 months ago

"article" vs "publication"

Two different things.

The link takes you to an article. Publications are in actual scientific journals, not intended for popular consumption.

[–] [email protected] 11 points 9 months ago (1 children)

Why have we accepted the standard of misleading headlines? "Oh well you didn't read the article, I guess you and 90% of eyeballs get to be fundamentally misinformed" is an unhinged take.

[–] [email protected] 4 points 9 months ago (2 children)

I never said a misleading headline was acceptable. I said the publication is not misleading and that it covers the criticisms dude up above was leveling.

[–] [email protected] 0 points 9 months ago (1 children)

The headline is part of the publication though.

[–] [email protected] 3 points 9 months ago

No, this is a popular science article, not an actual publication.

[–] [email protected] 2 points 9 months ago

It is misleading, for someone to be misleading they must mislead, and the headline misleads.

[–] [email protected] 14 points 9 months ago (1 children)

Often the author doesn't write he headline. Not sure it matters but most a bit of info.

[–] [email protected] 4 points 9 months ago (1 children)

You're not wrong, but we also should stop excusing, normalizing, and accepting wildly exaggerated for sales purposes titles of articles.

[–] [email protected] 1 points 9 months ago

We should stop accepting lies.

Unless there is some way this reaction actually did produce twice the energy input, it’s not misleading it’s a lie.