Energy Matters Forums

[erhco29]

Could someone give me an idea of the approximate temperature difference between 20c ambient above ground temp and 10 meters below the surface , or where would I find information relating to this question .

regards Erhco29

[Gordon-Loomberah]

That depends on your location! The temperature from about 2m below ground level downwards for at least a few metres is usually very close to the annual average temperature for that location. Here it's around 16-17C.
The BOM should have temperature data for somewhere near your location.

[erhco29]

Thanks for the quick response Gordon , would there be an appreciable drop in temperature at 20 meterst below the surface ?

erhco29

[Gordon-Loomberah]

I'm not sure exactly what it would be at 20m, but I suspect not too much different from what it is at 2m, in most places. Once you start to go down a significant distance, it warms up again, but I don't think that would be the case at 20m, unless in a geothermal/volcanic region.
The easiest way to find out would be to find a water bore of suitable depth nearby and lower a temperature logger/thermometer down on a cable to measure it, if you need to know precisely.

Why do you need to go so deep? It isn't really geothermal if you are only going 10 or 20m down anyway for use with a heat pump, it's ground coupled. Geothermal heat is generally found at much deeper depths.

[erhco29]

I am looking for a cost effective way to cool water not heat ,had an idea that by dropping it down to a depth of 20 meters inside a sealed casing and drawing it back up from the bottom it may have cooled sufficiently for what I require ( about 10 -15 c would be nice )
Being situated in Queensland ( South Burnett ) I would have assumed that the temperature at that depth would be markedly lower than the ambient temp above ground in the summer where temps range from 18-20 overnight to 32-38 during the day.

erhco

[Gordon-Loomberah]

For somewhere like Kingaroy the deep ground temperature will be around 20-21C, if you want 10-15C, you'll probably have to move to central-southern NSW ranges or Vic ranges, or even Tasmania Launceston's ground temp is around 12-13C.

[erhco29]

Thats ok I would rather put up with the heat than move south , thats a bit of a no brainer !!!!