Is fusion sh.t?

[Grumble]

Slightly provocative title perhaps, but as a science nerd (and occasional scientist) I’ve always been told how wonderful a fusion powered world would be. However, this is a sceptical look at fusion power and it’s made me stop and think.

https://beyondnuclearinternational.org/ ... confusion/

[dyqik]

Depends very much in how long the reactors last for before they have to be scrapped.

You can't beat the power density with anything renewable, but the lifetime cost and waste depends on how long the lifetime of the equipment is. IIRC, if the reactor doesn't last for ~30 years, it's not worth building.

[Gfamily]

In terms of power density it's worth noting that the power density of the core of the Sun is less than you'd get in a well run compost heap.
The challenge of fusion is to do orders of magnitude better than the Sun.

[Lew Dolby]

My compost heap could go supernove !!11!

[bjn]

I hadn’t cottoned onto the nuclear weapons proliferation aspects of fusion reactors, but I’ve previously heard most of the other issues he raised.

I don’t get the power density argument (usually used as a counter to renewables), given the amount of land happily used world wide for bio fuels. (Which are fricken stupid.)

[Gfamily]

My compost heap could go supernove !!11!

Unfortunately not - but if it was the size of the Sun it would make that corner of the garden mostly unusable.

[shpalman]

My compost heap could go supernove !!11!

Not even our sun would go supernova.

[dyqik]

I hadn’t cottoned onto the nuclear weapons proliferation aspects of fusion reactors, but I’ve previously heard most of the other issues he raised.

I don’t get the power density argument (usually used as a counter to renewables), given the amount of land happily used world wide for bio fuels. (Which are fricken stupid.)

It's not the strongest driving factor, but it does make a difference in certain economic cases.

[Bird on a Fire]

My compost heap could go supernove !!11!

Not even our sun would go supernova.

Probably needs more browns.

[dyqik]

My compost heap could go supernove !!11!

Not even our sun would go supernova.

Probably needs more browns.

It just needs more.

[jimbob]

Depends very much in how long the reactors last for before they have to be scrapped.

You can't beat the power density with anything renewable, but the lifetime cost and waste depends on how long the lifetime of the equipment is. IIRC, if the reactor doesn't last for ~30 years, it's not worth building.

I'm quoting myself in the ISF as I think the link to the 2013 IET article has now been broken.

And on the prospects for nuclear fusion - the IET (former IEE) magazine had an article on this recently

The thrust of the article is that achieving break-even is the easy part - once that happens, the real engineering challenges will have to be solved...

“We could actually build a reactor now, but it would not be economic because whilst the neutrons give up their energy and produce the heat we need to generate steam, they also damage the materials we have available now. The physics of fusion is now well mostly understood and resolved, but what is not resolved is the engineering consequences of generating these neutrons.

“You could build a reactor now with today's materials, but it wouldn't be economic because you would have to build a new reactor or remove and replace to core of the machine within two years. This includes everything inside the plasma chamber; ten billions dollar’s worth of plant.

[JQH]

That would be a "yes" then.

[Grumble]

I do wonder if the stellerator will overcome some of these problems - especially the parasitic energy demand presumably the core problem of almost all the energy being ejected as neutrons is the same as for tokamaks though

[Martin_B]

That would be a "yes" then.

So an exemption to Betteridge's Law?

[lpm]

MAJOR BREAKTHROUGH!

Time reduced from 30 years in the future to 29 years in the future.

First reduction since 1978.

[FlammableFlower]

JET gets a new record - 59MJ. Obvs, still a long way to go.

[shpalman]

They've successfully created as much energy as is in 1.6 litres of petrol and after ~25 years are able to run the thing for 5 seconds.

[IvanV]

JET gets a new record - 59MJ. Obvs, still a long way to go.

When you spend billions on some generating kit, you want GWs out of it. On average, continuously.

Here they have achieved about 11MW for about 5 seconds. They achieved 22MJ in 1997, with a somewhat higher peak power, but running for only a couple of seconds. After 25 years, they only just over doubled what they could do. They remain several orders of magnitude away from where they need to be.

We deduce progress is utterly glacial. Sometimes you achieve a breakthrough and progress speeds up. But there's no sign of that.

[dyqik]

JET gets a new record - 59MJ. Obvs, still a long way to go.

When you spend billions on some generating kit, you want GWs out of it. On average, continuously.

Here they have achieved about 11MW for about 5 seconds. They achieved 22MJ in 1997, with a somewhat higher peak power, but running for only a couple of seconds. After 25 years, they only just over doubled what they could do. They remain several orders of magnitude away from where they need to be.

We deduce progress is utterly glacial. Sometimes you achieve a breakthrough and progress speeds up. But there's no sign of that.

This is the stupidest possible take on this story.

[dyqik]

They've successfully created as much energy as is in 1.6 litres of petrol and after ~25 years are able to run the thing for 5 seconds.

I don't know how you can manage to be this stupid while working in research.

[IvanV]

This is the stupidest possible take on this story.

Apparently quite a few of us are suffering from the same stupidity, as you have noted on another thread.

That so many people should fall into the same utterly foolish error, would seem to merit some kind of a careful explanation of our error, rather than just ad hom.

[dyqik]

This is the stupidest possible take on this story.

Apparently quite a few of us are suffering from the same stupidity, as you have noted on another thread.

That so many people should fall into the same utterly foolish error, would seem to merit some kind of a careful explanation of our error, rather than just ad hom.

It's explained in the BBC news story.

JET is not, and was never supposed to be, a viable power plant. It's currently run as a research experiment for testing materials and technologies for the next generation of experimental reactors. Complaining that it doesn't reach breakeven is like complaining that one of shpalman's semiconductor devices reported in a paper can't run Windows.

[monkey]

This is the stupidest possible take on this story.

Apparently quite a few of us are suffering from the same stupidity, as you have noted on another thread.

That so many people should fall into the same utterly foolish error, would seem to merit some kind of a careful explanation of our error, rather than just ad hom.

It's explained in the BBC news story.

JET is not, and was never supposed to be, a viable power plant. It's currently run as a research experiment for testing materials and technologies for the next generation of experimental reactors. Complaining that it doesn't reach breakeven is like complaining that one of shpalman's semiconductor devices reported in a paper can't run Windows.

A real world and related example - the Chicago Pile (wiki cliky) was experimental, did 200W at most, and generally ran at 0.5 W. That's is a lot of expense and work for something that could only light a couple of light bulbs, at best. That didn't stop the experiment leading to useful fission reactors being a thing.

[IvanV]

JET is not, and was never supposed to be, a viable power plant. It's currently run as a research experiment for testing materials and technologies for the next generation of experimental reactors. Complaining that it doesn't reach breakeven is like complaining that one of shpalman's semiconductor devices reported in a paper can't run Windows.

Nor was it my intention to suggest so. The billions of pounds I mention is for a future commercial generator based on these principles, not JET itself. I was very aware as I wrote of it of the history of the 0.5W pile, which demonstrated a principle that quickly led to demonstrators of tens of MW, and thence to commercial generators of hundreds of MW. Exponential growth in performance. Whereas in fusion apparently we only achieved a doubling in 25 years, so it would appear by that UKAEA story.

The BBC article, (which I had not read at that point, only the UKAEA that FlammableFlower's linked) suggests that taking 25 years to get from 2s to 5s of operation is in fact a big breakthrough. If you can do 5s, as JET did it, then you should be able to do 5hrs with supercooled magnets. Which apparently the 2s achieved 25 years ago did not suggest. It is unusual for a "breakthrough" to be this non-obvious.

Though getting longer runs is only part of the battle, as the rest of the BBC article explains.

[bjn]

They would still be thermal generation systems, with all the associated capital costs of building all the plumbing to boil water, spin turbines and cool the hot waste water down. There are reasons coal power is becoming increasingly uneconomic, and that’s a main one. The same holds for fission reactors.