Energy plans

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olivier
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Energy plans

Post by olivier »

FWIW, I have just discovered and started reading a book (a draft actually) entitled Sustainable Energy - Without the Hot Air by David J.C. MacKay, Professor of Natural Philosophy in the Department of Physics at the University of Cambridge.
Everything is presented from a British perspective, however much of the reasoning, if not all the figures, remains valid for other countries.
It is too early for me to develop an opinion on the book, but I am interested in the global approach : (i) build a set of renewable "energy plans that add up" based on "numbers, not adjectives" then (ii) see what each plan looks like and implies in the real world.
What is more, this book is an interesting collection of data and links.
Fusion is considered under the tokamak approach which, in the most optimistic hypothesis, would come too late to be taken into account in the study.

jmc
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Post by jmc »

Yes, David MacKay gave a talk about energy in Culham. He has done an amazing amount of research on it.

Regarding fusion coming too late, the same might well be said for the Polywell approach, while I would reject it out right, if a functioning Polywell reactor is built in 5 years as Bussard said I would be astounded.

rnebel
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Post by rnebel »

jmc:

If p-B11 works, 5 years isn't unrealistic. The engineering on these systems isn't all that bad. Getting away from D-T makes it a lot easier.

MSimon
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Post by MSimon »

rnebel wrote:jmc:

If p-B11 works, 5 years isn't unrealistic. The engineering on these systems isn't all that bad. Getting away from D-T makes it a lot easier.
I have felt that if the project is Manhattanized (costs not significantly reigned in) it could be done in 3 to 4 years.

Given the size of the bailout proposed a couple of billion to quickly prove or disprove BFRs is chicken feed.
Engineering is the art of making what you want from what you can get at a profit.

Josh Cryer
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Post by Josh Cryer »

Philosophizing ahead:

The "Climate Crisis," even if you don't believe in it, has a lot of potential for something like Polywell. It's a political godsend in one way, because it means you can mandate, without hurting economics, having them put up everywhere. Politically speaking a mandate of that calibre would be definitely within the realm of possiblity.

"We have a pollution problem, and this machine can all but fix it completely. Thus we are granting tax breaks and other incentives for the market to go out and *build*!"

Sorry for the rambling here, as I believe it probably belongs in the "implications" forum. Just that I think 5 years is more than reasonable when you consider, well, the implications!

jmc
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Post by jmc »

rnebel wrote:jmc:

If p-B11 works, 5 years isn't unrealistic. The engineering on these systems isn't all that bad. Getting away from D-T makes it a lot easier.
It depends on the confinement of you device and how it scales. p-B may require less blanket materials to insulate against the neutrons but it will require far more magnetic insulation to protect the plasma itself. Which means, even assuming you can overcome the bremmstrahlung you're device will have to be bigger with a far higher field.

In an imaginary world without bremmstrahlung a p-B ITER would have to be bigger or have a higher field, the temperature would also be higher, this would increase the heat load on the divertor. The bremmstralung itself would only penetrate 4cm or so into the vaccuum vessel, and would place greater demand on the coolant, the higher field would place more stress on the device.

While I'm all for looking into other for fusion and adopting a pluralistic approach, I can't help but feel all this tokamak bashing in comparison to the "Polywell power plant" is a little unfair as it is comparing an imaginary device with a real one. And in such a contest the imaginary device always wins because everything always works perfectly until you actually build it.

rnebel
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Post by rnebel »

Jmc:
Two points….
1. The Tokamak isn’t any more “real” than the Polywell. Both of them produce thermonuclear grade plasmas and neither of them has been made into a reactor.
2. If a Polywell ends up having to be made enormous to beat transport losses, then we need to find a different concept. That’s a decision which should have been made for the Tokamak 30 years ago. The fact that it wasn’t made is why the Tokamak doesn’t have a customer.

jmc
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Post by jmc »

1. Has the WB7 hit DT equivalent thermonuclear breakeven like JET?! i.e. not counting magnets similar meassured neutron power output to heating power input. If that is the case I take back everything I said.

2. I think there's something to be said for continuing the tokamak concept from the point of view of materials testing and tritium breeding. I think that because to my knowledge there is no other fusion concept with any certainty of success out there. By doing the materials and tritium breeding work with tokamaks, hopefully if a more promising approach does emerge, its development will be leap-frogged over the material development stage which will already have been accomplished with tokamaks.

I think I agree with your point about not holding your horses for economic tokamak electricity.

rnebel
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Post by rnebel »

jmc:

Just because Jet hit Q ~ 1 doesn't mean that it is any closer to a practical fusion reactor than the Polywell is. If you want to use that criterion, then Los Alamos beat that a long, long time ago. Furthermore, if you can't make a practical reactor with D-T, then what is the point of the materials development with ITER?

drmike
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Post by drmike »

It's a high stress environment. If you can create materials to withstand high temperature and neutron impact they will be stable in just about any other environment.

But you don't need ITER to do materials testing. Any furnace next to a neutron source will work just as well.

TallDave
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Post by TallDave »

1. Has the WB7 hit DT equivalent thermonuclear breakeven like JET?! i.e. not counting magnets similar meassured neutron power output to heating power input. If that is the case I take back everything I said.
Since the heating power in WB-7 is zero, yes. ;) OK, OK, /snark.

The Q problem in a Polywell is related to electron losses rather than heating power. WB-7 is too small for fusion power to be greater than losses, but theory says losses scale as r^2 and power as r^7, so if we get JET-sized resources for IEC, we can find out whether at radii ~1-2M it's possible to get fusion power greater than electron losses.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

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