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Major breakthrough on nuclear fusion energy

bbc.co.uk

341–350 of 827 posts

Re: Major breakthrough on nuclear fusion energy

#341

Earlier quoted context omitted.

We haven't invented commercial fusion power, so none; but theoretically that is how they would function. Solar and batteries are nice but they're not yet cost effective. They're getting better. But you can't just handwave away real problems from your armchair viewpoint and assume thats all fine.

> We haven't invented commercial fusion power We don't have working fusion power, at all. > Solar and batteries are nice but they're not yet cost effective "Cost effective" is a judgement call, not physics. If I told you that the cost of coal-generated electricity was that your great-grandchildren would live in an impoverished and difficult world, you might not view that a particular cost-effective either, yet someho…

> We don't have working fusion power, at all.

Sure we do. Look no further than this article. We can make it, but its not commercially viable.

> "Cost effective" is a judgement call, not physics. If I told you that the cost of coal-generated electricity was that your great-grandchildren would live in an impoverished and difficult world, you might not view that a particular cost-effective either, yet somehow that's the "standard" against which things are judged.

Ah yes, think of the children.

Yes, coal is problematic, but the reality is that energy is expensive and we need a lot of it. If we tried to go full solar right now it would cost trillions of dollars, and the grid would still fail in the winter when heating is most important, and the economy would enter a massive depression as the cost of doing things gets both more expensive on average and extremely volatile.

You say this is a judgement call, not physics, but then go on to just broadly make assumptions about all of the relevant facts. You're not the one being logical and fact based. You're the one observing, yes, we have a climate crisis, and thus assuming that a radical solution for which you have no particular understanding of the economic or infrastructure implications is the right one because it's at least different from what we have now.

Renewables are good. They are getting cheaper. They're growing in capacity. And yet, I guarantee you, we cannot go full solar now. And I also guarantee that you do not have nearly sufficient of a view of the system dynamics to be making statements as bold as you are. This is hard. It's not just evil greedy coal mine operators ruining everything.

Re: Major breakthrough on nuclear fusion energy

#342

Earlier quoted context omitted.

Fusion produces a lot more radiation than fission, AIUI. What makes you think it will be any more politically viable to scale out than fission reactors?

There is no nuclear waste, what radiation are you measuring to come to this conclusion? neutrons that dissapear the moment the reactor switches off?

Activation of the reactor walls. The neutrons don't disappear; they're absorbed, and some fraction of the atoms that absorb them become radioactive themselves. I've seen lifetime estimates ranging from five to ten years for the walls, after which they'll be high-level waste.

Re: Major breakthrough on nuclear fusion energy

#343
post #175

In extension to this news and the press conference, one thing I am super excited about, is the private SPARC project and the MIT-spinoff Commonwealth Fusion Systems (CFS). If you don't know about it already, I would highly recommend checking it out (e.g. by searching YouTube for "MIT Sparc Fusion Reactor" for some fairly accessible videos on the theory behind why they should achieve fusion way faster than the current…

> Theory dictates that with stronger magnets, the reactor can be scaled down (with the square/cube, can't remember exactly), and thus cost and time to develop OTOH, in a tokamak, the plasma volume (and potential energy output) scales quadratically with the torus' aspect ratio (ratio of major to minus radius), so I'm not sure that tokamak-based fusion really is particularly suitable to miniaturization.

No post body was provided.

Re: Major breakthrough on nuclear fusion energy

#344
post #294

Earlier quoted context omitted.

Why? He dedicates huge amounts of money to worldwide public health, and is giving away the vast majority of his fortune over the course of his life. Why shouldn't I hold such a person in high regard?

From other comment > I mean, start with why his wife is divorcing him (Jeffery Epstein) and why he's no longer on the board at Microsoft(inappropriate relationships with staffers), then go into how he's screwed up public schooling in the US, then Microsoft under him. That's the easy stuff that you can see publicly.

The guy's work has directly prevented the deaths of enormous numbers of poor people worldwide. That trumps everything else in my book.

Also, don't fall for his wife's PR team. You have no idea why she's divorcing him. Claiming that the issue was Epstein is what any smart legal / publicity team would do in this circumstance.

Re: Major breakthrough on nuclear fusion energy

#345
post #332

Earlier quoted context omitted.

Fusion produces a lot more radiation than fission, AIUI. What makes you think it will be any more politically viable to scale out than fission reactors?

> What makes you think it will be any more politically viable to scale out than fission reactors? IIRC a major difference would be the danger potential in case of a "meltdown", since a fusion reactor wouldn't have kilograms or even tons of uranium etc. laying around to form another elephant's foot but "just" the irradiated reactor vessel which AIUI is both not as dangerous or as long-lived as fission fuel, a fission…

That is a sane, logical argument.

I'm just worried. If sane, logical arguments worked, then there'd be a lot more fission reactors in the world and a lot fewer coal plants.

Re: Major breakthrough on nuclear fusion energy

#347
post #251

Earlier quoted context omitted.

It runs into the spaceship problem where later iterations of a spaceship reach the destination first because new technology allows them to fly faster. At some point (maybe) materials and other technology will develop enough so that fusion becomes feasible on a decades or so timeline. Or solar & battery technology will develop to the point where fusion isn't really needed.

It's an interesting sci-fi thought, but why wouldn't the second spaceship just catch up with the first one and pick up the passengers to avoid their unnecessary travel time?

Incompatible docking apparatus, not backwards compatible. Engineers invented these doors, after all.

Re: Major breakthrough on nuclear fusion energy

#348

> It's not a massive energy output - only enough to boil about 60 kettles' worth of water. This made me laugh. How much more British can you get?

That's enough energy to boil those kettles dry, if my calculations are correct. To bring them to the boil, 59MJ would run about 600 kettles.

Water has a specific heat capacity of 4184J/kg/C. Lets say to get to the boil you need to go from 20C to 100C and that a kettle holds 1.75L.

59MJ / (80C * 4184J/kg/C) = 176kg ~= 176L ~= 100 kettles.

Water has a latent heat of vaporization of 2260 kJ/kg. So to boil it dry:

59MJ / (80C * 4184J/kg/C + 2260 kJ/kg) = 22kg ~= 22L ~= 12 kettles.

I have no idea what the journalist calculated.

Re: Major breakthrough on nuclear fusion energy

#349

> It's not a massive energy output - only enough to boil about 60 kettles' worth of water. This made me laugh. How much more British can you get?

It's also quite a helpful metric.

Most British people are aware that the national grid used to spend a lot of time making sure they had the power available to draw during the commercial breaks of mass-media TV events (series finales, half time in a cup match etc) purely for the nation boiling water with electric kettles en masse.

Great intersection of hard science (energy necessary to boil water + extremely efficient energy transfer) and everyperson knowledge. Good journalism!

Re: Major breakthrough on nuclear fusion energy

#350
post #294

Earlier quoted context omitted.

Why? He dedicates huge amounts of money to worldwide public health, and is giving away the vast majority of his fortune over the course of his life. Why shouldn't I hold such a person in high regard?

From other comment > I mean, start with why his wife is divorcing him (Jeffery Epstein) and why he's no longer on the board at Microsoft(inappropriate relationships with staffers), then go into how he's screwed up public schooling in the US, then Microsoft under him. That's the easy stuff that you can see publicly.

Even ignoring that, his fortune came from anti-competitive business practices in the 80s and 90s, without which, personal computing would have been in a much better place today.
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