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My borehole water is 22 degrees C


phil.g00
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My borehole water is 22 degrees C all year every year, --  must be an underground coal seam.

I can also pump it all day long as I estimate it capable at well over 20kl/hour.

I don't need more than normal usage per/day, but could pump for irrigation I suppose.

It takes 4.2kJ of energy to raise 1 L of H2O by 1 deg C. 

I can pump many liters/second and harvest say 10C of each liter.

So theoretically the right heat pump would make this borehole an energy goldmine.

But how do I make electricity?   

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22 minutes ago, phil.g00 said:

My borehole water is 22 degrees C all year every year, --  must be an underground coal seam.

I can also pump it all day long as I estimate it capable at well over 20kl/hour.

I don't need more than normal usage per/day, but could pump for irrigation I suppose.

It takes 4.2kJ of energy to raise 1 L of H2O by 1 deg C. 

I can pump many liters/second and harvest say 10C of each liter.

So theoretically the right heat pump would make this borehole an energy goldmine.

But how do I make electricity?   

No way...

https://en.m.wikipedia.org/wiki/Exergy

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2 minutes ago, phil.g00 said:

Do you mean there is no way to make electricity?

There are plenty of water to water heat pumps, but I don't really have a need for actual heat.

Or not this much of it anyway.

If ambient temperature is 10 °C, Max useful work efficiency would be 1-(283/293)...no way

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I don't understand what your trying to say, heat pumps are commonplace and there operating principles are well-known.

A heat pump works at higher than 100% efficiency, it uses say 1kW of electrical energy say to drive a fan through a radiator but manages to extract say three times that through the refrigeration process

An air to water heat pump takes large volumes of air sucks some over the energy out of ( cooling it ) an then through a reverse refrigeration transfers that energy to a lower volume water.

It can heat the water above the ambient temperature of the air. If you feel the back of your fridge it's warm, that is energy that is being extracted from the ambient temperature inside your fridge.

A water to water heat pump does the same thing, except water is more energy dense. In my case the ambient water is 22 deg C ,  which is very warm so skimming of a few degrees of say 90 % of the water with the heat pump with water I would be pumping into my tanks anyway and adding those few degrees to the other 10% of the pumped water should satisfy my hot water requirement.

Other than that though I cant really see a use for all this heat potential.

 

 

 

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41 minutes ago, phil.g00 said:

I don't understand what your trying to say, heat pumps are commonplace and there operating principles are well-known.

A heat pump works at higher than 100% efficiency, it uses say 1kW of electrical energy say to drive a fan through a radiator but manages to extract say three times that through the refrigeration process

An air to water heat pump takes large volumes of air sucks some over the energy out of ( cooling it ) an then through a reverse refrigeration transfers that energy to a lower volume water.

It can heat the water above the ambient temperature of the air. If you feel the back of your fridge it's warm, that is energy that is being extracted from the ambient temperature inside your fridge.

A water to water heat pump does the same thing, except water is more energy dense. In my case the ambient water is 22 deg C ,  which is very warm so skimming of a few degrees of say 90 % of the water with the heat pump with water I would be pumping into my tanks anyway and adding those few degrees to the other 10% of the pumped water should satisfy my hot water requirement.

Other than that though I cant really see a use for all this heat potential.

 

 

 

But you said, or i understood, that you wanted extract electricity from that warm water, and that's impossible.

If you want to improve the COP factor of a heat pump using that warm water instead of Air, i agree.

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Whereabouts are you? It won't be an underground coal seam heating the water (unless you are near a coal mine with a seam burning underground, but you wouldn't want to drink that!). Usually heated groundwater is due to circulation in the subsurface where groundwater is drawn from deeper than usual. The geothermal gradient in SA is around 1 deg per 100m, with about 15 deg ambient near surface, so to heat to 22 degrees it means that your water has circulated to about 700m below surface, been heated and brought back up again, unless there is an intrusion or something that is warmer than usual nearby. The geothermal gradient varies depending where you are, it is higher in the Bushveld complex, and the various metamorphic provinces, and will be lower in the sedimentary basins.

Here's a nice pic: https://www.researchgate.net/figure/Graphical-overview-of-the-calculated-geothermal-gradients-across-South-Africa-Map_fig2_321369675

Edited by DeepBass9
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Well obviously, I don't know for sure what heats the water.

But there is plenty coal about,  but its in the Tugela basin so I think there are environmental restrictions on mining the area.

The older locals tell me that at the time the area was tested for coal and was a better site for the present ISCOR Newcastle, but for the environmental impact.

Also not my water, but farm boreholes within a few km have a strong smell of sulphur from the water. The farmers just let the water stand in the tanks for a couple of days and the smell is gone. They say its perfectly drinkable.

A bit off topic but I'll tell you the story of drilling that borehole.

I drilled where the diviner told me two underground streams crossed at right angles to each other. He couldn't tell which stream was higher than the other though.

The drill site was about 200m from the Tugela, and about 12m higher than the water level of the Tugela. So, I thought I get seepage at least about that depth regardless of whether the diviner was right or wrong. To tell you the truth as a young engineer I had no faith in that hocus pocus, but as the diviner had picked a spot that was ideal placement for the borehole should there be water, I went with his location.

It was an anxious day, every meter costs plenty. I was in my mid twenties and by no means well-off, this was all my savings. I had budgeted for about 40m plus the cost of the pump.

 40m deep came and went, and well I'd didn't need a pump if there was no water, so I told them to keep on drilling. They ask after each 5m length.

70m down was still bone dry, the blue slate was coming up the hole like cement powder. Decisions, decisions.

 I queried the diviner and he just laughed and said there was big water here. I must admit at this stage I was beginning to think this was a con job.

At 77m we hit water, just like in the movies when they hit oil, the compressed air makes it like a mini-rainstorm. What a rush!

At that time the diviner ( who had been upgraded from zero to hero, in my eyes), was able to tell me I had hit the stream that ran perpendicular to the Tugela.

The proper thing to do is to drill a 10m sump through the stream. I wasn't bothered about hitting the second stream, I had my water.

At 87m we hit the second stream, and that was really big water. The drilling team said they had only seen one well nearly this strong in the previous 14 years. So I drilled another 10m sump and the borehole ended up 101m deep (20 x 5m lengths + a  1m drill bit).

The drill team estimated at  20kL an hour. They do that by sort of making a dam to channel the water at the top of hole and seeing down long the water coming out out the hole takes to fill a drum. This works for normal borehole delivery estimation, but in this case the compressed air was blowing that much water into the air that it was soaking everything in a 6m radius so only they were only measuring about half of what was actually coming out the hole.

In my own tests the water came up the hole to 12m below the surface, I pumped it with a 1.5 KW pump continuously for 3 days and on the third day while still pumping I measured the water at 15m below the surface. And yes, 22 deg C, all day, everyday if I want.

Sorry, to diverge but its not every day you bet your entire savings, and win. So I like telling the story.

 

 

Edited by phil.g00
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10 minutes ago, phil.g00 said:

At 77m we hit water, just like in the movies when they hit oil, the compressed air makes it like a mini-rainstorm. What a rush!

I have a second-hand story of my own. Just outside Windhoek they were drilling this borehole. The site was right next to an old cement feeding trough used by animals, again the diviner said it had to be there. A drilling operator with a slightly larger than average circumference was working the machine, and the client was standing around with a calculator attempting to figure out how much money he had to continue drilling. At that moment they drilled into an underground cavern and the entire spinning train of drilling machine dropped by a some distance while at the same time water was spraying everywhere. The client had such a fright, he just dropped everything and ran away some distance before turning around and cautiously returning. Water spraying everywhere and the drill operator had gone missing.

After eventually turning off the air pressure, they found the operator. He was lying on his back in the feeding trough, like a tortoise, unable to get back up.

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Yes, this borehole was a game-changer, deep water is bug-free and this is as clear as lemonade.  

Until then my then girlfriend and I where pumping out of the river into a farm dam and using flocculant.

A couple of days in between while the tank settles.

My parents would now drink tea when visiting, they told me later that the tea had been too high protein for their tastes before the borehole.

Edited by phil.g00
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My folks stayed on the slopes of the mountain at Hartebeespoort dam and their borehole water also had a sulphuric smell / taste.

Plenty of the boreholes in the area have the same problem, but the water is perfectly safe to drink and for irrigation.  The locals even brag saying it has certain health benefits.

 

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