Aquifer to be used for heating/cooling two schools in the Twin Cities

Looking out longer term, a similar system could be used to tap geothermal energy using an artificial subterranean mass (water, rock, whatever was appropriate/available) that is kept at a constant temperature by being significantly underground (so kept at a constant temp by the earth) and not subject to cooling.


Good idea. Geothermal heat pump often requires much digging for needed thermodynamics. Digging a well and putting coil in contact with ground water might be less costly. But how much water flow is needed? Multiple wells required?

Groundwater source heat pumps are rare, but not unusual, if that makes sense. They cost much more to install, but use much less energy. For public buildings it is a great way to go because the owner is likely to be the same for many years.

This is one area where building codes should be rewritten to encourage these types of systems. Builders don’t like them because of the upfront costs.

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I would think much depends on how deep the well needs to be. Some probably less than 100 ft. When practical worth considering.

The actual issue is what is the mass being tapped for heating/cooling, and if it is sufficiently deep enough to not be exposed to the atmosphere or to another source that could cool it significantly. Hopefully, if it is a non-geothermal source, the engineers have determined the mass is sufficient to maintain its temperature over time as it is being used by more and more sources for heating/cooling.

Many if not most schools have roofs and parking lots that are well suited for solar panels. When the schools are in session they could be generating electricity for the building. On weekends, holidays, and vacations, the excess power could be sent back into the grid.


Well there’s geothermal and there’s geothermal. If you’re going to get ALL the heat (or cool) out of the water that’s one thing.

My house as geo-thermal heat pump, meaning it uses the underground water as the cooling mechanism for the heat pump. We don’t have those giant fan-blade things in the backyard that ramp up like a 747 when spinning, which shed the excess heat (or vice versa for cool) when the heat pump is compressing the gas and using that for heat/cool extraction.

Instead, we get water from the ground (we live on a river) which is a nearly constant 55 degrees. When it’s 10 degrees out and heat-pumps are struggling to extract heat from the air, ours is using 55 degree water. When it’s 100 degrees out and the HVAC is running full tilt to keep things cool trying to dump load, ours is running efficiently using 55 degree water.

It still uses electricity, obviously, but it’s always efficient, which means it uses a lot less at the extremes. Spring and Fall I would presume the difference would be minimal.

So for a geothermal use of acquirer it wouldn’t have to go down as far as you might think, just far enough to extract water and be able to put it back in and let Mother Earth take care of the near constant temperature down there.