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"In experiments to date the energy input required to produce the temperatures and pressures that enable significant fusion reactions in hydrogen isotopes has fa
by madaxe_again 10y ago
"In experiments to date the energy input required to produce the temperatures and pressures that enable significant fusion reactions in hydrogen isotopes has far exceeded the fusion energy generated."
Wrong. NIF and others have achieved Q>1, albeit in single events.
http://www.bbc.co.uk/news/science-environment-24429621 http://www.bbc.co.uk/news/science-environment-24429621
- ohitsdom 10y agoI think "sustainably" is implied, and the author's next sentence makes that a bit clearer. > But through the use of promising fusion technologies such as magnetic confinement and laser-based inertial confinement, humanity is moving much closer to getting around that problem and achieving that breakthrough moment when the amount of energy coming out of a fusion reactor will sustainably exceed the amount going in, producing net energy.
- leephillips 10y agoNo, they haven't, not even in single events, although their press releases claim that they have. Their actual papers make it clear that the claim of >1 energy gain is a result of somewhat arbitrary definitions. There has not been a single shot on the NIF where more energy was supplied by the fusion reaction than was used to fire the lasers - it's not even close.
- SomeStupidPoint 10y agoAre you guys talking about different things? One seems to be talking about energy released by while the other is talking about energy captured from. I think GP was criticizing the news for making it sound like the first hasn't happened when only the second hasn't happened. (At least, in my understanding.)
- leephillips 10y agoNeither one has happened.
- Spare_account 10y agoThe BBC article linked above describes a very specific scenario which matches neither of your described options. "The amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel" This doesn't describe the relationship between the amount of energy injected by the lasers and the energy emitted by the fusion reaction. Presumably a lot of the energy injected by the lasers is wasted, some of it is absorbed by the fuel and it is this absorbed amount that was exceeded by the energy released. There is even a clearer statement in the article: "This is a step short of the lab's stated goal of "ignition", where nuclear fusion generates as much energy as the lasers supply." It seems to me that the following order of energy levels exists with present technology: Energy supplied to Lasers > Energy injected into system by lasers > Energy absorbed by fuel > Energy released by fuel > Energy captured to generate electricity from
- leephillips 10y ago'This is a step short of the lab's stated goal of "ignition", where nuclear fusion generates as much energy as the lasers supply.' Which is just what I was pointing out. And it's a large step from honest break-even, where you count the energy input into the laser system (it's not 100% efficient). And a huge step from practical break-even, where you count the energy required to run the plant.
- Spare_account 10y agoI was attempting to build on your contributions, but I decided to do it the same level as your comment because it made more sense to address SomeStupidPoint directly. Attempt at constructive criticism: I think your answers were a little too concise for some members of this audience and I decided to help out by expanding on your points a little. I've factored your comment about input energy into the lasers in my reply above.
- leephillips 10y agoThanks. I was probably too concise, but only had a couple of minutes.