Anybody know about geothermal heating?

[GregW]

Please note that heat pumps are just mechanical refrigeration units like your refrigerator or freezer. They are generally powered by an electric motor although direct mechanical drive from an engine is possible. The refrigeration cycle moves heat in either direction depending on how the system is hooked up. Heat pumps designed to hear and cool a residence or larger buildings are just much larger refrigeration units. These devices move heat energy from cold to hot against the “natural” flow of energy from hot to cold. The refrigeration units can move more heat energy than the mechanical (electrical) energy they consume. The efficiency of this heat transfer is proportional to the temperature difference. If the heat pump is trying to collect heat from a 0 deg air and transfer it to 70 deg house it will not be very efficient because there is not much heat available. Conversely, if the heat pump is acting as a AC unit pumping heat from a 70 deg house to the 95 deg outside is also very energy consuming. [for way more detail consult a basic Thermodynamics Textbook]

Geothermal source heat pumps use the heat storage capacity of the underground including aquifers, water saturated soil or dry dirt sufficiently deep (6 to 8 ft) to be insulated by the distance from the surface seasonal variation. Dry soil is a very good insulator. For example – If you have a garden, go out on a very hot day and dig a hole about 1 ft deep. Put your hand in the hole and feel the difference in temperature between the bottom of the hole and the top of the ground. It can be a surprising change. Geothermal source heat pumps take advantage of this insulation factor and use the soil, which is nearly always at the average long term temperature for the site, as the source and sink of heat energy. Given that most soil temperatures are around 50 deg in the US (more in the south less in the north and below freezing in parts of Alaska) the heat pump has a stable source of heat and a stable sink. The heat pump only has to, in the heating mode, transfer heat from 50 deg soils to a 70 deg living space. Under these conditions 1 KW of electricity can transfer many kW of heat. In the cooling mode the refrigeration unit does not have to run at all because the system can flow warm air over the 50 deg coil connected to the underground and use very little pumping energy to transfer a lot of heat (cool).

These systems are expensive to install and require skilled maintenance but so are many other options like solar heating but they are far more efficient because they do not “burn” a fuel on site to generate the heat. The refrigeration motor is powered from the grid and in much of New England is powered, at night anyway, by our resident nuclear power plants. The entire system is about a “Green” as it gets.
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[DragonFly757]

When we lived in Oregon we had a geothermal heating system. I love it, but it does need electricity to run the blower if I remember correctly.

The OIT campus in our town was fully powered by geothermal energy. There's a lot of volcanic activity there and it's a great source for geothermal energy.

Looks like the guys are guiding you much better than I can...but I wanted to add that I had it before and loved it.

[GregW]

The geothermal I was speaking about does not require warm ground to operate efficiently. Ground source geothermal will work off the heat in the ground at the annual average air temperature. If volcanically heated ground is available using the warm ground as a heat source is an obvious solution.

PS - a downright beautiful as the North West is I personally do not want to live where the mountains can go bump in the night. Ideally I will find a hot spring somewhere in New Mexico and retire to there. I love NH but I have gotten tired of the snow, sleet and cold.