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Aaron Thompson

Hey Gladwell...How old are you? I wonder if I might copy you? For really though--You get props. Tell us about the books you've read. Sincerely, and let me say authenically: you get props. I see hardwork there. You naturally write for re-reading? Cause that is interesting.

bake levine

Nice future for GEOTHERMAL I'd SAY! Heat is a form of energy and geothermal energy is, literally, the heat contained within the Earth that generates geological phenomena on a planetary scale. 'Geothermal energy' is often used nowadays, however, to indicate that part of the Earth's heat that can, or could, be recovered and exploited by man, and it is in this sense that we will use the term from now on.

Brief geothermal history
The presence of volcanoes, hot springs, and other thermal phenomena must have led our ancestors to surmise that parts of the interior of the Earth were hot. However, it was not until a period between the sixteenth and seventeenth century, when the first mines were excavated to a few hundred metres below ground level, that man deduced, from simple physical sensations, that the Earth's temperature increased with depth.

The first measurements by thermometer were probably performed in 1740 by De Gensanne, in a mine near Belfort, in France (Buffon, 1778). By 1870, modern scientific methods were being used to study the thermal regime of the Earth (Bullard, 1965), but it was not until the twentieth century, and the discovery of the role played by radiogenic heat, that we could fully comprehend such phenomena as heat balance and the Earth's thermal history. All modern thermal models of the Earth, in fact, must take into account the heat continually generated by the decay of the long-lived radioactive isotopes of uranium (U238, U235), thorium (Th232) and potassium (K40), which are present in the Earth (Lubimova, 1968). Added to radiogenic heat, in uncertain proportions, are other potential sources of heat such as the primordial energy of planetary accretion. Realistic theories on these models were not available until the 1980s, when it was demonstrated that there was no equilibrium between the radiogenic heat generated in the Earth's interior and the heat dissipated into space from the Earth, and that our planet is slowly cooling down. To give some idea of the phenomenon involved and its scale, we will cite a heat balance from Stacey and Loper (1988), in which the total flow of heat from the Earth is estimated at 42 x 1012 W (conduction, convection and radiation). Of this figure, 8 x 1012 W come from the crust, which represents only 2% of the total volume of the Earth but is rich in radioactive isotopes, 32.3 x 1012 W come from the mantle, which represents 82% of the total volume of the Earth, and 1.7 x 1012 W come from the core, which accounts for 16% of the total volume and contains no radioactive isotopes. (See Figure 1 for a sketch of the inner structure of the Earth). Since the radiogenic heat of the mantle is estimated at 22 x 1012 W, the cooling rate of this part of the Earth is 10.3 x 1012 W.
In more recent estimates, based on a greater number of data, the total flow of heat from the Earth is about 6 percent higher than the figure utilized by Stacey and Loper in 1988. Even so, the cooling process is still very slow. The temperature of the mantle has decreased no more than 300 to 350 °C in three billion years, remaining at about 4000 °C at its base. It has been estimated that the total heat content of the Earth, reckoned above an assumed average surface temperature of 15 °C, is of the order of 12.6 x 1024 MJ, and that of the crust is of the order of 5.4 x 1021 MJ (Armstead, 1983). The thermal energy of the Earth is therefore immense, but only a fraction could be utilized by mankind. So far our utilization of this energy has been limited to areas in which geological conditions permit a carrier (water in the liquid phase or steam) to 'transfer' the heat from deep hot zones to or near the surface, thus giving rise to geothermal resources; innovative techniques in the near future, however, may offer new perspectives in this sector.

Tarrin Anthony

I'm in high school and i'm doing a project on geothermal energy. we'd like specific answers.

how much would it cost to install a geothermal system for a 2000ft cabin by yellowstone?

How does it get the electicity and heat and stuff to the cabin?

I would be very much appreciated if someone would answer me.


I'm in highschool and I am currently working on my science project. I have to build my own "suistainable" house. I've never in my life heard about "geothrmal energy" until today. I really want to use this in my project. However, I don't know much about it. Can you please help me? I would really appreciate it if you helped me understand this better. I really need an "A" on this project! I would really appreciate it if you helped me.

Chris Koch

Interesting read. I'm an engineer who has just started my own geothermal installation business. This morning I thought I'd start putting together a blog on it. In doing a quick blog search I came across this article and the many comments. There are a large amount of questions (and they are common) I've seen posted above, and it would be difficult to address them all. But I would be happy to answer folks questions - in particular this is not a new technology. It's application to residential is somewhat new in that the industry is just starting to mature.

I'm from Kamloops, BC. I only say that as there was some comments above on one of our local developments here. Let me just say our soils in this region (dry silts and sands) are one of the poorest in thermoconductivity, yet it is still economically viable to put in residential-sized systems on small lots (vertical closed-loop systems).

We also do retrofits, so it is never too late to re-visit your home HVAC systems when the life of your existing system is coming to an end (ie when you need to replace your furnace).

There is some minor confusion over the term "geothermal". Historically this was applied to large industrial sized electrical generating projects (ie New Zealand, Iceland, etc...) where the Earth was used to create steam (think hot springs). The term is now being used for the small systems we associate with heating our homes. These systems no more require "hot" earth to work then your fridge would require a "glacier" to keep things cold.

Anyway, good to see a healthy plug for the residential geothermal systems.


kerry beaucrt

I was surprised at the high cost of the father's geothermal unit.
Having replaced standard heat pumps, that seems excessive. The question is how much of the cost was due to the fact that there was a pre-existing incompatible system.
AT $25,000, I wouldn't have made the switch. If he was all worried about the environment, switching to a biofuel oil to fuel his oil burner would actually have been more environmentally helpful than switching to the heat pump, since probably 70% of the electricity he's using to run it is being produced by fossil fuels. One thing's certain: the electricity didn't come from a wind turbine.
they produce practically nothing in the way of electricity (less than 1/4 of one percent).


I'm currently planning new construction on a summer/retirement home in Nova Scotia and am thinking about ICF (insulated concrete form) construction using radiant heat through a geothermal heat pump. My questions are; whether I will need a backup fossil fuel furnace or not? Also which geothermal system (trench or deep hole) is best to use or does it matter? Will solar or wind energy run a heat pump?

Dan Orzech

We just installed a ClimateMaster geoexchange system in a house we're building near Philadelphia, PA, and couldn't be happier. Don't have dollar figures yet since it's new, but we love the fact that the house is toasty warm, yet nothing's burning - no oil, no natural gas, nothing. Just energy from the earth below our feet (actually, three two-hundred foot wells below the driveway).

If anything, geoexchange seems to be more popular in Canada than in the U.S.: http://www.geo-exchange.ca. You might also find useful info at www.geoexchange.org.

I think ICF/geoexchange would be a good combination. We have no backup furnace, though we do have a pretty efficient fireplace, and lots of wood from our land.

Regarding trench vs. well/bore hole, I don't believe there's any efficiency difference. If you have the room, trenching is probably cheaper.

I don't see why a geoexchange system couldn't run on wind or solar, though you'd need battery backup. We looked longingly at solar PV, but just didn't have the money. Loved the idea of being off the grid entirely, but couldn't justify it financially. Pennsylvania at the moment has no government incentives for doing solar, funding ran out last year.

For anyone else reading this in Pennsylvania, I'm thinking about getting together a coalition of geoexchange users, installers and manufacturers to push the state government for more support. Anyone interested is welcome to contact me at orzech@well.com.

Ed Pawlowski

Food for thought....

Have been considering a Geo system but the area required for a system is a problem which led me to thinking of alternative geo ground sources...

From what I understand if you have a well for domestic water needs that same well may be used as a Geo source for the heat pump eliminating a field all together.

Which leads to the question why not use a municipal water supply, or better yet use the cesspool or municipal waste system leading from the average dwelling. To my knowledge it would require nothing more than a heat exchanger between the sewage pipes and the heat pump....

Eliminating the field would also reduce the cost and make retro installations a lot more feasible.

Any comments welcome....

Eric Lange


I recently installed I believe Canada's first retro-fitted geothermal system for a commerical application. The building complex is almost 70,000 sq ft with approx. 10,000 of office and 60,000 of warehouse including 24 ft high ceilings for the warehouse.
We invested $540,000 in total in the geothermal system, including changing the lights in the office to a T8 system.
Our office is a cozy 72 degrees, our warehouse is being challenged during this extreme cold snap where outside temp. is well below freezing, our goal was to have the warehouse at 55 degrees but right now is 50 degrees, when temp. outside is at freezing or above we can maintain our target in the warehouse of 55 degrees and more.
I encourage all business owners to look at the savings of geothermal, as the savings are REAL and make good business sense, and make great enivronmental sense

Michael McColl

I've seen an application of this sort in operation in northern minnesota where it can easily drop to well below zero for long periods of time during the winter and well over 100 degrees for uncomfortable lengths of time in the summer. I believe the guy I knew ran his system through a pond that he had on his property and as far as I know, he's very happy with his system. I'm planning on eventually installing something like this for a 100 year old brick building that I've been restoring in the same part of Minnesota. I have the available surface area and I'm sure that in the long run, this will be worth the investment.

mike mccoll

Brad Anklovitch

Since heat pumps heat the building slower than fossil fuel burners,there is thermostat controllers that will measure the temperature outside. Once the temperature outside starts to fall it will start increasing the internal temperature to reduce the lag time. Your building will not lose the heat as quickly. FYI


If you have looked into solar energy as a method for heating your home, panels are usually the first things that come up. There are, however, other unique methods.

The Solar Heating Aspect You Have Never Heard of Before

The power of the sun is immense. The energy in one day of sunlight is more than the world needs. The problem, of course, is how does one harness this power. Solar panels represent the obvious solution, but they have their downside. First, they can be expensive depending upon your energy needs. Second, they do not exactly blend in with the rest of your home.

Passive solar heating represents a panel free method of harnessing the inherent energy found in the sun for heating purposes. If you come out from a store and open the door of your car in the summer, you understand the concept of passive solar heating. A wide variety of material absorbs sunlight and radiates the energy back into the air in the form of heat. Passive solar heating for a home works the same way as the process which overheats your car in the parking lot.

Thomas Marshall

Does anyone know if lasers have been used to "drill" vertical holes for geo-exchange heaters? The Colorado School of Mines (Dr. Ramona Graves) has been trying to use lasers to drill for oil and gas and they may have to go to depths of 20,000 feet. If geo-exchange heater units can work with vertical depths of only 300 to 500 feet, it seems that finding an inexpensive and much less disruptive (to your landscaping) way of putting the piping in might make the new systems much less costly.

What portion of the costs of a vertical system does the drilling represent?

Any responses would be most welcome. E-mail comments to: tfmarsh@comcast.net



You are correct to say that most of the answers to our environmental issues already exist. This geoexchanger thing is just the tip of the iceberg. There is a technology called ICF (insulated concrete forms) construction wich lowers heating and cooling costs by 50 to 70 percent. There is something called vacuum panel insulation wich has an R value per inch of 300. Then there are the solar and wind options. You combine these technologies with some common sense like not building a 7,000 sq ft home with 100 windows, and you can cut your heating and cooling energy use by up to 90%. We don't have to build the gigantic nuke plants, the "clean coal" (lol) plants and the ridiculous use a gallon of fossil fuel to get a gallon of ethanol idea that the corn mafia (Cargill, ADM) is pushing.

Brad Anklovitch

This question is for anyone who owns a geothermal system. What kind of maintenance and support do you need after you have your geothermal system installed?

David Hatherton

Great article Malcolm. Good to see this type of press finally getting out there on this technology.

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