Re: theWatt Podcast 73, concepts behind geothermal heat pump

well done with podcast 73.

An air conditioner is a heat pump. When heating your house, a heat pump can be run backwards to change the orientation of the thermal cycle and thus provide heat to your house in the winter.

Heat pumps are not practical here in Cleveland Ohio where I live because the extreme winter temperature differential between the outside air and the required output temperature of the air discharge in the house. They use them in California just fine.

One way to make the heat pump practical here is to lower the temperature differential between the desired output and the discharge side. This is where geo thermal heat pump comes in. The earth is at a constant temperature.

Consider the more familiar the air condition cycle. Waste heat is discharged during the summer. It would take less energy to run the air conditioner if the thermostat was increased by a few degrees. There is a less obvious chose to save energy. Assume that there is a constant heat gain through the homes insulation (and however heat gets into the house). By exchanging energy not with the ambient outside air but through a cooler geothermal heat exchanger, a larger temperature differential will require less energy.

The geothermal heat pump is about saving energy via decreasing the amount of energy required to compress gas by way of exploiting the constant temperature of the earth.

By the way, there are horror stories about geothermal heat pump installations that have gone wrong. It is reported that in one installation, the ground surrounding the heat exchanger froze a very large chunk of the guys yard. Beofre the installation this hadn't happened. The huge ice block slid down a hill and very slowly smashed into the house.