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Author Topic: How can old mines heat our cities?  (Read 2610 times)

Offline thedoc

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How can old mines heat our cities?
« on: 11/09/2012 20:30:02 »
How can flooded mineshafts beneath our cities be used to heat our homes? Diarmid Campbell talks about a pilot scheme in Glasgow that could do just that...
Read a transcript of the interview by clicking here
or Listen to it now or [download as MP3]
« Last Edit: 11/09/2012 20:30:02 by _system »


 

Offline CliffordK

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Re: How can old mines heat our cities?
« Reply #1 on: 12/09/2012 00:42:22 »
It sounds like a great idea.  The water might help stabilize the mine shafts too (although it would cause any metal to rust).

A while ago, I suggested doing something similar with abandoned oil wells which could be a lot deeper, and thus having more geothermal heat.

http://www.thenakedscientists.com/forum/index.php?topic=42739.0
 

Offline Boogie

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Re: How can old mines heat our cities?
« Reply #2 on: 12/09/2012 05:16:16 »
Out gassing of ores and minerals can occur when subjected to water. These gasses can be toxic. This would need to be considered.
 

Offline CliffordK

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Re: How can old mines heat our cities?
« Reply #3 on: 12/09/2012 06:20:49 »
Out gassing of ores and minerals can occur when subjected to water. These gasses can be toxic. This would need to be considered.
Certainly if one used oil wells, the water is often very briny.

One option would be to reinject the water into the mines/wells.  Even if pressurized, it might help prevent subsidence.  Perhaps separating out residual oils or valuable minerals.
 

Offline Boogie

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Re: How can old mines heat our cities?
« Reply #4 on: 13/09/2012 01:01:41 »
One option would be to reinject the water into the mines/wells.  Even if pressurized, it might help prevent subsidence.  Perhaps separating out residual oils or valuable minerals.

I'm not sure that would be a good idea with a mine. The mine interior would first need to be sealed so that it maintains the pressure without causing a geyser somewhere. Then any little earth movement along faults can open new and old fissures which would spew forth toxic mixtures of nastieness. Even if you were to get the mine sealed to hold the pressure, there is risk of blowing out the side of a mountain. It nearly happened in Leadville, Colorado.

Quote
Natural mountain water is currently backed-up in a labyrinth of old mine-tunnels that are connected to a collapsed 2.1-mile drainage tunnel. [CNN] Leadville fears that the old shafts and tunnel are too full to hold new water from this year's heavy snows; that any added pressure of new water will force all water out of its containment inside of the mountain above the town.

http://voices.yahoo.com/leadville-colorado-mega-flood-911079.html


Edit : Also, I would like to add that the water in the mine could also lubricate fault lines causing slippage and earthquakes. My vote is against this idea.
« Last Edit: 13/09/2012 01:11:30 by Boogie »
 

Offline chris

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Re: How can old mines heat our cities?
« Reply #5 on: 17/09/2012 17:46:55 »
These are really moot points, since - as Dr Campbell explains in the interview - these mine workings were allowed to flood naturally when work ceased and the pumps were switched off over a century ago...
 

Offline Boogie

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Re: How can old mines heat our cities?
« Reply #6 on: 17/09/2012 21:56:15 »
Thanks, Chris.

Perhaps you're right. Not being familiar with heat pump technology, I was under the impression that perhaps the air or water or air/water mixture from the mine was being transported through residence and businesses via some sort of duct work. This seemed a bit risky but I'm sure that the  medium transporting the heat is clean and safe and if a rupture or leak occur on the surface, there would be no cause for alarm. I'm also sure that measures are being taken to remove methane build up and other possible causes for underground explosions/dangerous situations have been concidered.

I may have missinterpreted his comments, but my response was mainly toward CliffordK's posts which appeared (to me) to be advocating the use of pressurizing water and using mines shafts as conduit. I thought this would be a bad idea, or at least point out some of the potential hazards.

I appologize.
 

Offline CliffordK

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Re: How can old mines heat our cities?
« Reply #7 on: 17/09/2012 22:24:17 »
One of the dangers with some oil wells is that the liquid (briny water + oil) is actually under a significant amount of pressure from the weight of the earth above.  Thus, BP had a significant amount of problems stopping the flow of the oil at the Deepwater Horizon well.

Perhaps a non-collapsed mine shaft would not have the same characteristics sending pressurized liquid to the surface, and thus a liquid exchange would also be easier.
 

Offline chris

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Re: How can old mines heat our cities?
« Reply #8 on: 17/09/2012 22:28:03 »
In this circumstance the aim is to exploit the temperature differential across the mine; the deeper workings are warmer than the more superficial shafts. By abstracting small volumes of water - on the order of tens of litres per minute - and removing the heat with a heat exchanger, the cooler water can be returned more to a less deep, cooler mine section. There should be sufficient differential energy to run the system, they estimate, for a century...
 

Offline Mazurka

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Re: How can old mines heat our cities?
« Reply #9 on: 24/09/2012 12:49:38 »
This is precisely the same principle as ground source heat pumps, often  suggested as a very "eco" form of heating just on a bigger (and presumably more efficient) scale.

The volumes of water suggested and the length of time elasped since working mean that acid mine water drainage is not going to be a problem.

Whilst this may not be suitbale for every old mine, generally, what an excellent idea, particularly as low cost district type heating has not really developed in the UK (historically due to the relatively poor economics of it) and this could be seen as returning something to communities that have been adversely affected by mining (or the decline of mining) and reduces reliance on fossil fuels - which are the principle method of space heating in the UK - a rather poetic irony, I would suggest.

 

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Re: How can old mines heat our cities?
« Reply #9 on: 24/09/2012 12:49:38 »

 

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