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PostPosted: Sat Nov 07, 2020 5:23 pm 
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It has potential, anyway:

Dutch Brewery is Burning Iron Powder as Fuel

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PostPosted: Sat Nov 07, 2020 8:11 pm 
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I'm not sure what the advantage of this is over hydrogen. I'd been thinking it'd work with most metals (believe it or not, aluminum dust is quite inflammable), but there's just so much iron out there, there's a huge advantage for iron over just about any other metal.

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PostPosted: Sat Nov 07, 2020 8:26 pm 
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chas wrote:
... but there's just so much iron out there, there's a huge advantage for iron over just about any other metal.

I don't know how other metals would measure up to iron in this, but what struck me is how the spent fuel, iron oxide (rust, basically), can be converted back into burnable iron. Maybe the cost of doing that outweighs the advantages now, but the suggestion of a more or less closed loop is most intriguing.

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PostPosted: Sun Nov 08, 2020 5:25 am 
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How are you supposed to produce iron powder? the article mentions "grinding iron" and it looks like it was ground very fine. That has to be a fairly energy intensive process. Also how pure does the iron have to be?


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PostPosted: Sun Nov 08, 2020 7:14 am 
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There are a fair few articles about this, mostly in Dutch though. Here are two : from De ingenieur (the engineer), the video in that may be of use, and from Eindhoven University

You'll have t oget your own translations though.

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PostPosted: Sun Nov 08, 2020 9:08 am 
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Mr.Gumby wrote:
There are a fair few articles about this, mostly in Dutch though. Here are two : from De ingenieur (the engineer), the video in that may be of use, and from Eindhoven University

You'll have t oget your own translations though.


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PostPosted: Sun Nov 08, 2020 3:52 pm 
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PB+J wrote:
How are you supposed to produce iron powder? the article mentions "grinding iron" and it looks like it was ground very fine. That has to be a fairly energy intensive process.

I would count that end of it as a one-time investment. If you could burn iron as a way to power the grinding of iron, then any energy expenditure is more or less self-contained, and eminently sustainable.

PB+J wrote:
Also how pure does the iron have to be?

No idea. I would imagine the purer, the better.

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PostPosted: Tue Nov 10, 2020 7:29 am 
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PB+J wrote:
How are you supposed to produce iron powder? the article mentions "grinding iron" and it looks like it was ground very fine. That has to be a fairly energy intensive process. Also how pure does the iron have to be?


I would assume there's a sweet spot regarding the size of the particles. As we all know, iron oxidized very readily, so if the particles are too small, they'll be entirely or mostly oxidized. If they're too big, they'll burn too slowly for a self-sustaining process. Just a WAG, I'd think some fraction of a mm -- maybe 10-200 microns, but the size would need to be pretty uniform for the process to be efficient. As for purity, it would be insensitive to lots of impurities, but too much oxide will mean not much energy, and too much of one of the stainless-passivating metals (e. g., Ni or Cr) would probably kill the reaction.

I had misinterpreted how the Eindhoeven group were pitching this. They're basically considering it a way to store non-constant power sources such as wind or solar, for which it would work well. I still haven't been able to find a comparison of this process to hydrogen, which is much simpler but is difficult to store.

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PostPosted: Tue Nov 10, 2020 7:52 am 
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chas wrote:

I would assume there's a sweet spot regarding the size of the particles. As we all know, iron oxidized very readily, so if the particles are too small, they'll be entirely or mostly oxidized. If they're too big, they'll burn too slowly for a self-sustaining process. Just a WAG, I'd think some fraction of a mm -- maybe 10-200 microns, but the size would need to be pretty uniform for the process to be efficient. As for purity, it would be insensitive to lots of impurities, but too much oxide will mean not much energy, and too much of one of the stainless-passivating metals (e. g., Ni or Cr) would probably kill the reaction.

.


The article I linked to above says something about that (I just noticed I made a mistake with the links, linking to the same article twice):

Quote:
We kijken bijvoorbeeld naar de grootte en de vorm van de ijzerkorrels. Zijn die groter, dan branden ze langer in de installatie. En ronde deeltjes verbranden mooier, maar laten zich weer lastiger vervoeren door de buizen


Which translates roughly as For example we look at the size and shape of the grains of iron. When the yare larger, they burn longer in the installation. Round grains burn nicer but are harder to transport through pipes.

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PostPosted: Tue Nov 10, 2020 2:20 pm 
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chas wrote:
I would assume there's a sweet spot regarding the size of the particles.
I guess the quantity of nitrogen oxides created and needing to be removed from the exhaust could be a factor in this.


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PostPosted: Wed Nov 11, 2020 8:14 am 
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It makes sense I guess to think of it as a way to "store" energy gained in solar/wind etc. A solar plant could grind iron and then burn it as needed. But "grinding iron to uniform particles" doesn't seem like a very efficient process and as chas mentioned you'd have to keep the particles from oxidizing.

I'm thinking using excess solar capacity to produce hydrogen would make more sense?

I've ling thought that we'd have been better off if Edison had won out over tesla and we had individual home generators rather than regionally distributed AC. Nearly every device in the house has to transform AC to DC--what are the efficiency losses?

It' not hard to imagine either every house having a generator, just as every house has a furnace, or maybe generating stations on every block serving x number of houses


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PostPosted: Wed Nov 11, 2020 12:09 pm 
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PB+J wrote:
It makes sense I guess to think of it as a way to "store" energy gained in solar/wind etc. A solar plant could grind iron and then burn it as needed. But "grinding iron to uniform particles" doesn't seem like a very efficient process and as chas mentioned you'd have to keep the particles from oxidizing.

I'm thinking using excess solar capacity to produce hydrogen would make more sense?

I've ling thought that we'd have been better off if Edison had won out over tesla and we had individual home generators rather than regionally distributed AC. Nearly every device in the house has to transform AC to DC--what are the efficiency losses?

It' not hard to imagine either every house having a generator, just as every house has a furnace, or maybe generating stations on every block serving x number of houses


The thing about generating power is that the efficiency goes up with scale. A diesel or kerosene generator for a home is nowhere near as efficient as a steam turbine in a power plant. I used to know how much was lost in transmission, but can't call it up at the moment.

The big thing between Edison and Tesla was AC vs DC. And if solar farms start going up in deserts, that will be transmitted via DC and Edison will be happy.

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PostPosted: Wed Nov 11, 2020 2:20 pm 
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PB+J wrote:
... you'd have to keep the particles from oxidizing.

Considering that oxidized iron can be converted back to metallic (I don't know if that is the right word) iron, that seems, at least on paper, to be not so much of a problem. The whole point of burning iron is that when it's burnt, what's left is oxide, but nothing's lost since you can recycle it back to its former state. My guess is that so long as the system's up and running, natural oxidization is going to take more time than can catch up with the cycle of burning/regeneration. I should think that while some oxidization in storage may be inevitable and present a comparative loss of BTUs, that might be weighed negligible enough for the system to be able to pay for itself.

How's the cold fusion Holy Grail going, lately?

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PostPosted: Thu Nov 12, 2020 6:33 am 
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Nanohedron wrote:
I should think that while some oxidization in storage may be inevitable
Store it dry away from oxygen? Nitrogen or CO2 should be inexpensive.


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PostPosted: Thu Nov 12, 2020 6:05 pm 
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david_h wrote:
Nanohedron wrote:
I should think that while some oxidization in storage may be inevitable
Store it dry away from oxygen? Nitrogen or CO2 should be inexpensive.

That sounds possible.

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