Mine, slag heap and geothermal energy

[bebeours]

I live in Charleroi, and for those who know, they know what it is all about.
The entire region is covered with heap (coalmining waste). By digging a heap for a few centimeters, you get intense heat. This phenomenon is due to its black color and its mass, but also to chemical and physical reactions. Basically, the carbon it contains burns.
The former miners of the region to whom we owe so much talk of the temperature of 60 ° C in the deepest galleries.

I would like to know if these two sources of energy are exploitable and in what proportion.

I had imagined a metal stake planted at the top of a slag heap with a few pellet plates and a thermal diffuser on top to supply a few lamps as a witness.
Do you think I would have a result, or should I do otherwise?

As for the mine at 60 ° C, you have to go down to 1000m, and in addition, I believe it is closed. So, not very usable.
I still ask myself this question. Instead of heating with coal for so many decades, wouldn't it have been better to recover all this heat underground to heat our settlers?

[cortejuan]

Hi,

I dig up this thread dealing with waste heat recovery. I did a quick search and amazed I didn't see any big projects (apart from the "Heaps" project) and very little in-depth discussions. Is the argument of the limited duration of exploitation relevant and sufficient?

I would add that if deep geothermal energy is still subject to the hazards of the subsoil (karsts, pockets of water, etc.) in this case, the environment is known and relatively homogeneous and the risk of pollution of groundwater (often before by ecologists) is zero.

So unrealistic or uninteresting idea?

cordially

[chatelot16]

60 ° C is not much ... the means to use this low temperature have a lousy yield ... the fault in the carnot which determines the maximum possible yield depending on the temperature

worse it can be warm because the large mass does not let the heat come out easily ... it would be enough to want to use this cahleur to cool everything without getting much

the most serious would be to use the heaps as fuel ... it's black like coal, too poor to be sold like real coal, but still good to use mixed with other fuel in thermal power plants a little improved ... it was not profitable to do it 50 years ago but it will inevitably become so

[cortejuan]

Hi,

If it's 60 degrees, I agree but according to other sources, the temperatures would be higher than 1500 degrees (provided you probably dig towards the center of the heap). The 1975 explosion (I believe) would corroborate these high temperatures.

The operating time on the other hand seems to me a real limit.

Going back to 60 degrees, it's even better than deep geothermal energy (let's say at 100 meters what had been proposed to me)) for which the temperature gain is a few degrees but which affects the thermal mass around the borehole . In this case a heat pump is essential.

cordially

[chatelot16]

for me if it heats, it's that it can burn ... so you have to put in a boiler ... not let it heat in pure waste in unnecessary heap

[cortejuan]

Hi,

on the one hand the heating is due to an enormous pressure and not only to the presence of combustible material of which the combustion is a consequence. Without coal, it would still heat up.

Finally, many slag heaps are part of the landscape and cannot be gutted to supply a boiler. The people of the north have already given a fair amount of sacking of their environment, so reopening quarries in slag heaps with catastrophic returns (at least two thirds of the mass is sterile, especially in the most superficial parts because the most recent ) would amount to emptying a slag heap to create a new one nearby.

So frankly, I don't think it's playable, but we should take a closer look at the "slag heaps" project which perhaps evokes this hypothesis.

cordially

[Christophe]

Damn I missed this interesting subject from 2009! Using a heap in solar thermal buffer seems to me a good idea, remains to be seen if it is really the solar heat which is stored there or a slow combustion ...

Because otherwise it's not sustainable ...

dedeleco also apparently ... too bad it would surely have interested him!

[chatelot16]

if 2/3 are sterile it means that a third is combustible!

there are certainly around these teril a certain number of people who would be ready to commute with their wheelbarrow to heat themselves instead of buying fuel oil ... and to make the reverse shuttle to get rid of the ash ... and in a few centuries the heap with 1/3 of fuel will be replaced by a heap of ash with 0,5% of fuel

it is not the energy source of the century, but it is not negligible

it would be much better if it were organized correctly with a real thermal power plant, or an incineration plant ... which should be the same thing