[legohead]

I've asked before but didn't get an answer. If we can achieve stable fusion, what are the plans for getting the power out?

The guy in the article said you just do the same thing as coal or any other plant - generate steam. But we're talking about millions of degrees vs a couple thousand. Does it really scale that simply?

[DennisP]

Plasma temperature is high but total heat is similar to other power plants. The atoms are moving fast but there aren't many of them. So basically, surround the plasma with a neutron-absorbing coolant and you're good. CFS uses molten FLiBe salt, and some others use a molten mix of lead and lithium. Then you run water pipes through that.

[chihuahua]

I'm just guessing, but I imagine if you have a way of maintaining something at a temperature of millions of degrees, there's always a way to transfer that heat to some other thing. For example, by moving a gas past the very hot object, thus heating up the gas, and then moving the gas through a more conventional heat exchanger, where you generate steam for a steam turbine. Depending on the speed of the gas, it absorbs energy but isn't necessarily heated to the same temperature of millions of degrees, so it doesn't destroy the heat exchanger.

I think this is somewhat similar to how a fission reactor is used to drive a steam turbine in an ordinary nuclear (fission) power plant.

[XorNot]

Deuterium-Tritium fusion produces a neutron each time. Neutrons are not charged and so escape magnetic containment slamming into the reactor wall, transferring heat to it.

This is how you get heat out, it's also how you breed more tritium from lithium.

[pencilguin]

This, like all fusion startups (except maybe one), is a scam.

That is to say, none of the investors will get any of their money back. If they are OK with that, fine. But probably most are not. You can think of it as a stupidity tax: enough money to invest was also enough to hire somebody to explain how they are throwing their money away. But they didn't.

One reason (of several) that it is a scam is that, to get the power out usefully, you need a thousand tons of "blanket" to absorb kinetic neutrons and turn them into heat. You need a high proportion of lithium in your blanket, so that the neutrons hitting it can breed the tritium you will need for fuel tomorrow.

But running a full-scale power plant all day will only breed a few grams of tritium, that you must somehow sift out of your thousand tons of "blanket", at parts-per-billion concentration. Nobody knows any way to do this. But without doing it, you have no fuel to use tomorrow.

Even if you could get enough tritium, those hot kinetic neutrons are blasting all of the physical structure of your reactor, weakening it, and also making it extremely radioactive. After a remarkably short time, you have to replace all the solid parts. But they are all fantastically radioactive, so you need robots to do it with. Those robots do not exist. The used-up parts are, anyway, not like regular nuke waste; they will mostly decay in a century or two, probably.

Until then, presuming you could scare up tritium fuel, you would have a thousand tons of super-hot "blanket" you need to run water through pipes in, to boil and drive a steam turbine. But steam turbines, too, need expensive periodic overhauls.

Meanwhile, solar panels and wind turbines are producing the cheapest power the world has ever known, today. No radioactivity, no tritium, no persnickety steam turbines. Just clean power.

So, nobody would buy your super-expensive fusion plant even if it worked, because it would cost so much to operate you would need to ask a lot more money for its output than anybody will pay.

But the people running the startup have no need to care about any of that. They have fun making big expensive experiments with your money, cater in expensive lunches, and drive Ferraris, because why not? When the money runs out, they go do something else.

There is no force on Earth powerful enough to make them give any of the money back.

Another big scam, BTW, is NRGV, "Energy Vault", traded on public markets at $2B cap last I checked. Apparently it is not considered fraud to collect investment money for things that cannot work.

[willis936]

>Nobody knows any way to do this.

Correction: you don't know any way to do this.

https://www.osti.gov/pages/servlets/purl/1394392

Meanwhile the super expensive power plant can run in the winter and not require fossil fuels or magic energy storage.

[pencilguin]

The paper is about how to prevent production of tritium. It mentions breeding tritium, but not how to extract grams of it, every day and at negligible cost, from a thousand tons of lithium salt. So, my point stands.

Do futile jabs at renewables, which are being deployed at industrial scale as I write this, serve to make fusion startups less scammy?

[willis936]

Read section 4 again.

Renewables will not replace fossil fuels to an acceptable degree without first solving energy storage. The question is "is industrial energy storage cheaper than fusion energy". Not such a clear answer when the order of magnitude of either of those is not established.

Do futile jabs at fusion, but also try to keep in mind the goal is legacy, not identity.

[pencilguin]

Any civil engineer can explain numerous storage alternatives to you. It is all centuries-old tech, excepting only novel battery chemistries and catalysts.

[jpgvm]

A much cheaper fission plant does the same thing without all of the insane technical challenges of fusion.

[pencilguin]

And yet is also uncompetitive.

[jpgvm]

I don't think we built enough to really know that. Lets see how China goes for costs first and then reassess.

[thedrbrian]

>Meanwhile, solar panels and wind turbines are producing the cheapest power the world has ever known, today. No radioactivity, no tritium, no persnickety steam turbines. Just clean power.

No dispatching either

[rolph]

there is more than just thermal energy, but so far it all looks like steam generation. if more experimentation reveals the persistence of the fusion reaction during perturberance of magnetic flux, we may be able to couple into the field with static coils.