Geothermal Heating

Over the weekend I went to a workshop on geothermal heating. Walking in, I was probably the most ignorant of the attendees, and so provided the leaders with a service of what it’s like to deal with absolute zero. But an enthusiastic AZ. IN Vermont, the biggest contributors to CO2 are driving cars and home heating with fossil fuel.

There were about 70 people in attendance, from all over southern Vermont; a third were contractors. The rest of us were home owners looking to get educated.

First, there is a distinction to be made from geothermal energy, which taps geothermal reservoirs, harvesting the steam generated therein for heat and electricity. Think of those lucky Icelanders swimming in outdoor thermal pools in mid-February. These reservoirs are generally near tectonic plates. There are some in the west, lots offshore along the east coasts of the Americas and west coasts of Europe and Africa. It’s expensive to tap.

Geothermal heat can be had from the relatively cool (but not frozen) ground as well. Even in New England, the technology has advanced enough to extract heat from either ground water at 50 degrees or from air at 0 degrees F, or with the newest variable speed pumps, even less.

Basically, (and I mean, really basic, here) in water-to-air transfers, you are sucking the heat out of water that is fifty degrees, by running it through a compressor like the one in your fridge (only in reverse, right?). This removes 10 degrees of heat per pound from the water. That heat is then pumped into your house, now toasty. My brain had to stretch around the idea of extracting heat from something that is, frankly, cool. But it can be done.

This on ground source heat pumps from good old Wikipedia:

Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat. Heat pumps can transfer heat from a cool space to a warm space, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one. The core of the heat pump is a loop of refrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Heat pumps are always more efficient at heating than pure electric heaters, even when extracting heat from cold winter air. But unlike an air-source heat pump, which transfers heat to or from the outside air, a ground source heat pump exchanges heat with the ground. This is much more energy-efficient because underground temperatures are more stable than air temperatures through the year. Seasonal variations drop off with depth and disappear below seven meters due to thermal inertia.[2] Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling). Some systems are designed to operate in one mode only, heating or cooling, depending on climate.

The most important thing, Harold Rist, the presenter on water-to-air transfers, said, was to get a system designed for the north. Too many people don’t go deep enough and then resort to using hyper-poisonous dry gas to thaw out the slush running through their systems. That or they have to use bigger compressors that are more expensive to run.

Then there is air-to air transfer, which is particularly well suited to heating a few rooms. You basically have the air source heat pump, working much like that refrigerator, only backwards, to extract heat from cold air and pump it into your house. The unit is the size of a suitcase, can be set up right outside the rooms in question, as long as it’s a bit protected from ice-build-up so the fan can work properly. You have a fan unit on the inside that looks like a two foot baseboard heater, mounted on the wall.

Both of these technologies are highly environmentally friendly. They currently enjoy federal tax rebates, so you can install a system for (in the one instance we were given) around $7000.

The downside, in my view, is the reliance on electricity to run your pumps, an iffy proposition in my neighborhood. The power doesn’t tend to go out when it’s sunny and warm. So maybe a hybrid system, with a wood stove backup, is the answer.

The first thing I have to do is getting something blown into our walls, whose insulation has settled about six inches off the ground. No point in heating the great outdoors.

Now that you have eaten your spinach and you understand geothermal heating (sort of) I’ll try to upload the Frida and Na Balom pictures.