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Michael J.

I ran this post by a friend who is a well-known and well-respected expert in high-performance energy systems and his response was:

"Amazing how much mis-information can be packed into a short article!"

So I think you'd want to get an engineer involved if you head down this path. I agree with the closing point, re breakthroughs, but nothing is without hidden costs and trade-offs.


It is great to have a post about this technology.

But the terminology may be a bit outdated.

People in the industry now tend to all this technology “Geo-exchange” or “Ground Source Heat Pumps” to avoid confusion with “Geothermal Power” which refers to technologies that extract power from underground heat sources (with temperatures above average ground temperature).


why don't we hear more about this? Because the rot starts at the top in this country, for example a VP from the oil industry who terms conservation "a personal virtue" that obviously is not worth trying to persuade people to adopt (as opposed to stem-cell restrictions, which apparently are of critical importance to the survival of the republic)

S Iyer

Joel, could you go over what you
used to calculate interest?

Are you compounding the $2000/year
in savings assuming that I invested it in an S&P 500 index traking fund?

What is the depreciation rate of
the initial investment?

I'd argue that after the end of year 5, I probably have about $22,000 (lost $3k due to depreciation) + $10,000 (savings from the system) + the compounded annual interest assuming I invested the $2k savings per year in an S&P 500 index fund. That number is much better than -16.74%.

I'm no financial analyst, so I got no problem if you can point out to me where my assumptions are wrong.

pat joseph

The rot may start at the top, Mike, but here's a surprise: Guess who else uses ground source heating and cooling? Would you believe George W. Bush? It seems its part of the design at the Crawford ranch. I had nearly forgotten.

Sylvia Warren

Very informative. Thanks to you and your Dad for sharing and delineating the 3-P (profits--i.e., ROI, people and planet) benefits of a home geo-thermal system. The current state of this technology is another indicator that a serious lack of vision keeps the US "addicted" to oil.


I've been thinking about geothermal a lot lately. I'm looking into buying a house, and thinking about the work required to make the conversion. A question I've had, though, is what kind of impact, if any, will wide-spread use of geothermal have on the environment, and on its effectiveness? I'm wondering if anyone has done some modeling of ground temperature when different densities of houses are using geothermal, and considered what impact higher/lower temperatures might have. I just want to make sure that collectively we don't make the same mistake previous generations have made - blithely ignoring the consequences of their actions. Perhaps the research has been done, but I'm just not aware of it. Please let me know if it's out there.

Joel Schopp

It turns out I'm no finanical wizard either. I forgot to count that the savings from the system would also earn interest. I feel a lot like consumer reports double counting depreciation of the Prius. My bad.

So the geothermal system does beat the bond, here is the (revised) amount of time it takes for the geothermal system to win out at the various rates of return on investment.

5% - 21 years
7% - 31 years
10% - never


Some things to note before taking into account the various cost savings or returns on investment (or lack thereof).

The higher the price of oil relative to electric costs, the more it makes sense financially. The opposite holds true too.

It simply must be cheaper in a new home than retrofitting an old one, not even taking into account the sunk cost of the oil heater or air conditioning.

The more extreme the heat or cold where you live, assuming no start-up or other operational problems due to extreme temperatures, the more the savings. Along the same lines, if you face both hot summers and cold winters you ought to do better than someone who lives in a location that is more moderate year round, such as a southern area with a coastal breeze during the summer.

Finally, it is hard to quantify the air quality issues the author mentioned. How do you put a price on that? If it is "well known" that the air quality is better, your house's resale value may well outstrip the capital costs themselves in an expensive real estate market, and be worth little in the boonies.

In short, your mileage will vary.


In chinese rural areas,people have already been talking about,or even adopting this technology,only that they don't call this "geothermal" system or something technical like that,but rather "rudimentary or primitive" air-conditioning.And they barely know the principles and innerworking of this systme either when asked about it.i THOUGHT it was just a fake science experiment and hoax,but after raading your old man's lucid exposition of this technology,I begin to realize what a great thing those chinese peasants are doing.and for a country oil crisis has begun to loom very large,like China,this shouldn't just be conducted in rural areas and confined,a wide public awareness campaign is what I'M thinking.By the way,Malcolm,your suggestions for urban adaption of this technology,such as the mall parking lot exploitation stuff,are truly insightful and clever.
We need more things like this one,the world over.Any take?


Malcolm Gladwell, you remain one of my heroes.


And, I'm going to have to add your dad to my list! :)

Alexander Karelis

Your writing is elegant in both style and content. Thank you for suggesting new ways for me to think.

Graham Gladwell

Yes, KWH in my description should be replaced by watts,
I am sure that my description is faulty in many other respects. Is there not an expert out there who can give an accurate description? Remember that I am just a mathematician. My wife once stated that I regularly talk authoritatively about things I know nothing about. That way I can fool most of the people all of the time. Remember too that I am Malcolm's Dad!


You don't necessarily need a football field to do geothermal, but I suspect in the absence of space, you need a lot more money:


JP Elverding - the Netherlands

whatever the engineering integrity, it's the example and explanation that make it very worthwhile to read. A point proven by the reactions I'd say.

Will see what is done over here although, when I start digging, I'll get my feet wet at 2", that might make some difference.



I wrote the finance guy at my high school and he wants to install this at my school. I was wondering who to contact that would install geothermal heating at my high school. We are a small private school in Northern California Please write me or boboxen@pacbell.net if you have information.


I was thinking of putting an inground pool in an inground basement and it occurs to me that if you can put the water pipes thru a lake or river, you could probably put them in the bottom of a pool about 12 feet or more underground and cool your house and heat your pool water at the same time?


I heat my house in Eden Prairie, Minnesota with a geoexchange heat pump. My system was designed to heat my house to 23 below before backup (electric resistance) heat is needed. I have done considerable analysis, and a smaller system, one that would heat my house to zero before backup heat was needed should have been installed, but the point is the system can be designed to handle the whole load, it is just more expensive. As for financials, I calculate the operating cost to be equivalent to using a 95% efficient furnace with natural gas at $4.60 per million btu and electricity at $0.054 per kwh. Our local utility has a 'WindSource' program where we can pay $0.02 per kwh extra to get electricity generated by wind(above and beyond what the state requires). I buy all of my electricity through this program, costing me an extra $150 per winter, but I have the satisfaction of knowing that I put nothing into the atmosphere to heat my house, and my heating dollars stay in the state. For a more detailed analyis, see the Minnesota Department of Commerce website, edocket 04-820.11. The reponses to my petition by our local utility and the Department of Commerce are absurd and misleading.

Rick P

"the persistent notion that real solutions will require some future technological breakthrough"

Not surprising when you take into account the money that is made on research that produces nothing.
For a energy researcher a solution means the end of their job. Just as a cure is a brings death to the cash flow of a medical research lab.

Also it real hard to corner the market with technology that is covered by an expired patent.

This is why scams like the Hydrogen Economy and Ethanol are the ones that get promoted.


For those figuring the payback for installing a ground-source heat-pump so far in this thread, I've only seen the payback figured in today's energy costs.

Here in the northeast U.S., since 2000 my heating fuel K-1, has risen by 60% while my electricity has only risen by about 15%. Past performance does not assure future performance but the evidence is mounting that we are reaching the limits on how much more oil and natural gas can be pumped out of the ground. Our ability to generate more electricity is only limited by free market return on investment and our own self-imposed regulations.

The math here tells me that in my lifetime, we will be living in a heat-pump dominated society for heating and cooling needs.

I do work for a heat-pump manufacturer and am familiar with some cutting edge companies in the same field.

Big strides are being made to improve air-source heat pumps for cold climates. There are machines on the market now that can extract heat below 0 F without relying on electric strip back-up heat which most of today's heat pumps commonly use. For more on these systems, follow this link:
(I do not work for this company)

If you are intersted in how heat-pumps are used to efficiently creat hot water, follow this link:
(I do work for this company)

Heat pumps have also been succesfully used in clothes dryers and to extract drinking water out of humid air, but these uses are more "Popular Science-neat-things-you-can-do-with-heat-pumps" than commercially viable uses of the technology-- the kind of stuff that tickles my geek sensibilities.

Jessica Stone

Gladwell for president.


This is really cool. I wish my apartment building had this kind of system - in the sweltering heat and mugginess of Washington, DC I get so sick of having the a/c on all the time. It's gross to think of how little fresh air we get when it's really hot. What a difference it would make to people's health to avoid the wild swings between too much heat in winter and too much a/c in summer!

And excellent point about Bush's notion that some kind of technological breakthrough is needed - completely false. It just takes the will to apply what already exists.


Thanks for this post. I'd never realized that geothermal heating could be implemented on a personal level like this before.



The first point you made is dead on: "Iceland is a great example of the use of geothermal energy." Iceland is a paragon of the benefits of geothermal heating. The entire country, "the land of fire and ice," has converted 90% of its energy to hydroelectric power and 70% of its heating to geothermal. And this is really something, given the length and strength of Icelandic winters.

It is truly revolutionary in this near total transformation.

But I'll have to disagree with your second point: "They have none of the pollution difficulties that we have."

The economy is dependent on fossil fuels: fishing, automobiles, and planes (as a hub for constant flights between the USA and UK). As a result, Iceland produces more greenhouse emissions per capita than any other nation in the world - even considering their transition to hydroelectric energy and geothermal heating.

This reliance on fossil fuels is especially damaging to Iceland, which lacks natural oil resources of its own. The country must import oil to maintain its fishing industry (which accounts for a whopping 70% of exports).

Oil imports have damaged the economy. Because of the detrimental effects, Iceland has started efforts toward another transformation. The plan is to convert all fossil fuel use into hydrogen fuel cells within the next twenty years.


But thanks again, Malcolm, for this interesting post.

David Neubert

Thanks to Dad. I want to build one of these now. I always thought it was much more complicated.

Brandon Keepers

I live in Holland, MI, which uses a "hydronic snow
and icemelting system"--water pumped through tubes under the street and sidewalk--to melt snow in the winter. Best of all, it uses excess heat from the local power plant, so it uses very little energy, and probably saves the plant from pumping 90 degree water into the river. Right now, it only runs through a few blocks of the downdown, but I hope they expand it to cover more of the city.

This is the only link I could find about it: http://www.wirsbo.com/includes/get_docs.php?id=68

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