Favorable Comments made by ONR on Polywell Fusion

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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WizWom
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Postby WizWom » Thu Jul 22, 2010 10:38 pm

D Tibbets wrote:
Helius wrote:A "Mouse over" says "SMES" which means.....
http://encyclopedia.thefreedictionary.com/Superconducting+Magnetic+Energy+Storage


That brings up the question: Are superconductors a good energy storage mechanism? They can be loaded with a lot of current. Certainly if they fail, they can make a big bang. Can reasonable magnets (such a 5 meter diameter and 10-20 Tesla superconducting magnets store more energy than comparable flywheels? Presumably, they could deliver their energy very quickly, like a capacitor.


The formula for energy in a magnetic field is pretty simple:
U = B^2*A*l/(2*μ0)
So, we need AREA and LENGTH to be defined; if we say 2m circle Torus, 5m dia, then Area is π and length is 10π.

U = 20^2*5*π^2/(4π*10^-7) ≈ 15.7 GJ = 4.36 MW-h

There are serious suggestions a loop of 100 miles might be good - at 10T!

I of course, would suggest multiple smaller systems - you'd hardly use up any area, even putting 5m coils every 10m, installing a bank of 256 of them. You'd be talking 160m x 160m for about a GW-h
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Aero
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Postby Aero » Thu Jul 22, 2010 11:49 pm

WizWom wrote:
D Tibbets wrote:
Helius wrote:A "Mouse over" says "SMES" which means.....
http://encyclopedia.thefreedictionary.com/Superconducting+Magnetic+Energy+Storage


That brings up the question: Are superconductors a good energy storage mechanism? They can be loaded with a lot of current. Certainly if they fail, they can make a big bang. Can reasonable magnets (such a 5 meter diameter and 10-20 Tesla superconducting magnets store more energy than comparable flywheels? Presumably, they could deliver their energy very quickly, like a capacitor.


The formula for energy in a magnetic field is pretty simple:
U = B^2*A*l/(2*μ0)
So, we need AREA and LENGTH to be defined; if we say 2m circle Torus, 5m dia, then Area is π and length is 10π.

U = 20^2*5*π^2/(4π*10^-7) ≈ 15.7 GJ = 4.36 MW-h

There are serious suggestions a loop of 100 miles might be good - at 10T!

I of course, would suggest multiple smaller systems - you'd hardly use up any area, even putting 5m coils every 10m, installing a bank of 256 of them. You'd be talking 160m x 160m for about a GW-h


WizWom - OK. That's good. Now, the homework assignment. Come up with the dimensions of a device to replace a battery. Say a 52 kW battery like EESTOR was claiming a couple years ago. And guess at the weight.
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Postby MSimon » Fri Jul 23, 2010 8:13 am

...Do you still claim the Navy's interest in a technology [like Polywell] demonstrates evidence of its viability?


Nope. Just evidence of promise. Viability will be demonstrated when a machine is powering a ship or delivering power to the grid.
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Roger
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Postby Roger » Fri Jul 23, 2010 12:20 pm

Viability for funding, sure. As long as good results are produced at each step. And note that polywells overall viability has leapt ahead since 2006.
While the ITER gets delayed- Cost doubles, goals are recast.
MSimon wrote:
...Do you still claim the Navy's interest in a technology [like Polywell] demonstrates evidence of its viability?


Nope. Just evidence of promise. Viability will be demonstrated when a machine is powering a ship or delivering power to the grid.
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

WizWom
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Postby WizWom » Fri Jul 23, 2010 1:03 pm

Aero wrote:WizWom - OK. That's good. Now, the homework assignment. Come up with the dimensions of a device to replace a battery. Say a 52 kW battery like EESTOR was claiming a couple years ago. And guess at the weight.


Um... 5kW is a "speed", not an amount.
Let's see - the Tesla Roadster battery pack holds 53 kWh; if we want a maximum diameter of 1m (2π length) then the Area must be

53,000*3600*2*10^-7/(20^2) = A = .0954
Which is a circle 35cm in diameter.

It should be noted that this is AIR in the center; the reason is that with the mu factor on the bottom, you don't WANT it to be high. But that works for us, in that it makes it lighter.
However, now to engineer it from here, and get some idea of the mass, you need to select a superconductor material and temperature and figure out how many turns you need to reach 20T, and then multiply it all out for the amount of superconductor, then add in an insulating case and refrigerator unit.

But, I think it would definitely come in below the 450kg for the battery pack for the Tesla Roadster. But it would be much more expensive.
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Aero
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Postby Aero » Fri Jul 23, 2010 4:20 pm

But, I think it would definitely come in below the 450kg for the battery pack for the Tesla Roadster. But it would be much more expensive.

Lighter weight quick charge power source would be good in the automotive industry. Especially with charging stations becoming available. So the cost is the problem, coupled with the risk of the refrigeration drawing down the power while parked until ... well, until refrigeration fails for lack of power then the whole device heats up. No explosion because there is no energy left. But then aren't there some complexities involved in re-energizing the super conductor magnets?

What we need is a super conductor cooled with liquid nitrogen, or higher temperature cryogenics. I think MRI machines use trivial amounts of liquid nitrogen to maintain superconducting temperatures. MSimon (IIRC) has posted on liquid nitrogen requirements elsewhere. Maybe one liter per week?
Aero

Enginerd
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Postby Enginerd » Fri Jul 23, 2010 5:11 pm

Aero wrote:Lighter weight quick charge power source would be good in the automotive industry. Especially with charging stations becoming available. So the cost is the problem, coupled with the risk of the refrigeration drawing down the power while parked until ... well, until refrigeration fails for lack of power then the whole device heats up. No explosion because there is no energy left.


The biggest problem (next to cost and lack of charging stations) I see for using superconducting energy storage devices for automotive applications comes from car wrecks... Imagine your newly charged up Tesla RoadMonster 9000 gets into a wreck... While you are standing next to your formerly beautiful car yelling at the idiot that just rear-ended you, all the liquid nitrogen drains out, the coils warm up, and suddenly stop superconducting... It seems to me that might ruin your entire weekend.

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Postby MSimon » Fri Jul 23, 2010 5:22 pm

53 KWh in 6 minutes? That requires a source that can deliver 530 KW i.e 440 volts @ 1,200 amps. Per charging station. Two cars charging and you need over 1 MW. Not counting losses. Now suppose you live in a large city where you have 2,000 cars on quick charge at any given time. You will be needing a 1 GWe power plant just for automotive charging.

And don't forget to keep the charging stations losses low. And mind the battery doesn't overheat.
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Skipjack
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Postby Skipjack » Fri Jul 23, 2010 5:39 pm

You will be needing a 1 GWe power plant just for automotive charging.

And?
Where is the problem with that? If polywell works out, that should not be a problem, right?

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Postby MSimon » Fri Jul 23, 2010 5:44 pm

Skipjack wrote:
You will be needing a 1 GWe power plant just for automotive charging.

And?
Where is the problem with that? If polywell works out, that should not be a problem, right?


Time and money.
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kunkmiester
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Postby kunkmiester » Fri Jul 23, 2010 6:00 pm

Don't forget, you really don't need to recharge it in 6 minutes, a few hours is fine. The home charger would run it in six hours or so during the night for your drive to work.

The only charger that would need to have a high rate is the "gas station" on the highway, which you would want to charge your car in half an hour while you eat lunch for the afternoon's driving, after which you'll be getting a motel and doing a slow charge again. The "gas station" would also end up charging a LOT more than a couple of cars though, as well as running a cryo plant to fill up spare LN2 tanks.

What's the rate for converting KWh to TNT equivalent? The important safety issue here are time to minimum safe distance, and chain reactions. The coil will probably be in a dewar flask, so pretty sturdy there, but if one does go off, a multi car pile-up will probably results in several fire crackers.

We also are planning a fusion reactor that will probably result in large amounts of MgB superconductor being made. Since this mass production will probably make it one of the cheaper ones, your car will probably use it, unless it's a luxury or sport model. So, how's a 20T coil made from MgB?
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chrismb
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Postby chrismb » Fri Jul 23, 2010 6:18 pm

TNT = ~4GJ
kWh = ~4MJ

Carrying around energy always has its dangers. Infrastructure energy always has its dangers. For a given energy type, the more of it, the more dangerous it is.

Safest common energy/engine combination yet devised = diesel fuel. (it'll put a lighted match out, if you throw one in to a bucket of the stuff.)
Most economical mass produced energy/engine combination = diesel. (~40MJ/kg, 100kg diesel = 1 tonne TNT = 1,000kWh)

.....now go figure what fuel will [continue to] dominate....

93143
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Postby 93143 » Fri Jul 23, 2010 6:47 pm

Maybe I've missed something, but wouldn't there be... practical considerations... involved in carrying around 20 T magnets in cars, completely aside from the danger of loss of superconductivity? Or could a superconducting case solve the problem without drastically reducing energy density? How strong would such a case have to be?

Enginerd
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Postby Enginerd » Fri Jul 23, 2010 6:54 pm

93143 wrote:Maybe I've missed something, but wouldn't there be... practical considerations... involved in carrying around 20 T magnets in cars, completely aside from the danger of loss of superconductivity?


As in wiping your laptop hard drive while you drive to work?


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