Geothermal relative to aquafer?

Question

If a subdivision, i.e. 400 homes, were to use geothermal technology, both for heating and cooling, assuming 45 degrees north in the midwest United States, and assuming a substantial aquafer exists, (note, solar heating, and cooling, using Stirling technology), how much will the ground water change temperature...(not a trick question......seriously)... if 1 person does it, it's a good idea.....if everyone does it, is it still a good idea?

Answer 1

You both are missing the point. A ground-source heat pump is the only way to efficiently heat and cool a house or a building using a sub-surface ambient temperature. An aquifer is desirable for heat exchange, but not necessary.

Much like an air-to-air heat pump, a ground source heat pump collects and concentrates heat calories from the ground (basic Boyle’s Law concept). Where I live in the northeast, the ambient ground temperature at 200 feet is 55°F year-round.  That is a lot of transferable heat. In the summer, the heat pump runs in reverse – dissipating heat back into the ground as it cools houses and buildings.

Even in a large sub-division, the induced temperature changes from this geothermal heat exchange will be minimal at best. Given the mass of underlying bedrock and the constant movement of ground water, raising or lowering the sub-surface ambient temperature even a few degrees with current geothermal technology would be difficult.

I have an air-to-air heat pump and wish I had installed a ground-sourced heat pump when I had the chance. Good thought provoking question though.  

Answer 2

You are missing some info...   For one if you are using regular groundwater or that from a hydrothermal hot spring of some type.  Normal ground water is like 70 degrees and hydrothermal hot springs can get up to like 200 degrees.  That is a big diffrence.  One will just warm the air and the other you could cook salmon in.  In Iceland they use the hot spring variety.  But lets assume since you said 45 degrees in the midwest US you are talking about the Ogallala Aquifer that underlies most of that area.  In that case the pipes used to pump water through houses are ment to warm or cool the house to an equal temperature to that of the aquifer temp.  So if it is 85 F outside then the water will chill the inside temp to near 70 degrees.  If it is like - 20 F outside then the temp inside will be warmed to near 70 degrees.  Basically provides a source for stable temperature either hotter or colder than the ambient temperature.  Like living in a cave, same temp all year round.  

Yes it is a good idea, will save big $$$ in cooling and heating costs.