251–260 of 833 posts
This website is seriously infested with reflexive contrarians and it’s a not healthy.
If you turned that heat energy into electricity (our ultimate goal here) you'd have:
(2.5 megajoules produced * 50% loss in conversion to electricity) - 2.1 megajoules input = negative 0.85 megajoules generated
This is still cool of course, but we're still way off from making this anywhere near feasible.
Good write-up to temper expectations at https://twitter.com/wilson_ricks/status/1602088153577246721 My TLDR (from a layman): * The output is greater than the energy *in the lasers*, but the lasers deliver 1% of the energy required to power them. Need 100x improvement to break even. * Converting the generated energy into electricity would cut the output in half. We need a further 2x improvement here, so it's ~200x to…
Earlier quoted context omitted.
I don't see that scaling anytime soon, still more than two orders of magnitude away. But never say never.
The exact numbers depend on the form of fusion in question, but fusion does have some several places where it has quite substantial x^n growth possibilities, where "n" is definitely greater than one and can be greater than two at times, sometimes even substantially so. This means that there is some real, concrete hope for improvement in a way that, say, solar could never improve more than 4-5x where it is now because…
The capability of the NIF to get positive energy from the energy that they impart on the Hohlraum itself is neat, but I constantly discount any milestones that Livermore/NIF report, because the inertial confinement approach has such higher barriers to commercialization than tokamak style approaches, that I just consign it to "boondoggle" in my head.
Yeah, the lasers could be 20x more efficient, and yeah, they probably could figure out how to pump 10s of targets into the chamber per second, but the energy extraction is just completely missing from the considerations. The engineering challenges are a whole 'nother level for NIF, a big barrier to usability.
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The analogy doesn't really work. The utility of a steam engine was obvious to antiquity, but they did not have the materials technology to build it. They did not need basic science to do steam power. The first practical steam engine predates the understanding by chemists of combustion. It was invented when phlogiston was still the going theory. NIF on the other hand is already a miracle of materials science. An absol…
People in antiquity did build a functioning steam-powered engine, but dismissed it as a curiosity. https://en.wikipedia.org/wiki/Aeolipile
They correctly dismissed it as a curiosity because it was far too inefficient to do anything useful with the amounts of fuel they would have had available. They couldn't have made a more efficient one because they didn't have any idea how to construct reasonably uniform pressure-bearing cylinders.
Real innovation didn't happen until much later on, at British coal mines because 1. there was lots of fuel because it's already at a coal mine, 2. there was a useful task for the work in pumping water out of the mine, and 3. materials technology had advanced enough to make it possible to construct an engine that did a useful amount of work from a manageable amount of fuel.
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"That’s because they had to use 500 MJ of energy into the lasers to deliver 1.8 MJ to the target – so even though they got 2.5 MJ out, it’s still far less than the energy they needed for the lasers in the first place. In other words, the energy output (largely heat energy) was still only 0.5% of the input."
Partly that's because they use laser tech from the 1990s, with less than 1% efficiency. Now we have NIF-class lasers with over 20% efficiency. https://physicstoday.scitation.org/do/10.1063/pt.6.2.2021102...
Good write-up to temper expectations at https://twitter.com/wilson_ricks/status/1602088153577246721 My TLDR (from a layman): * The output is greater than the energy *in the lasers*, but the lasers deliver 1% of the energy required to power them. Need 100x improvement to break even. * Converting the generated energy into electricity would cut the output in half. We need a further 2x improvement here, so it's ~200x to…
Earlier quoted context omitted.
"That’s because they had to use 500 MJ of energy into the lasers to deliver 1.8 MJ to the target – so even though they got 2.5 MJ out, it’s still far less than the energy they needed for the lasers in the first place. In other words, the energy output (largely heat energy) was still only 0.5% of the input."
I don't see that scaling anytime soon, still more than two orders of magnitude away. But never say never.
It's quite easy to see that replacing the lasers, the capacitors, etc. with more modern technology would have an immediate effect. But it doesn't matter until doing the reaction at all makes sense. That's what they are focusing on.
A leap forward or two might be worth celebrating along the way, sure, but we're at least 3 orders of magnitude away from actually generating net power here.