Tapping the Earth For Home Heating and Cooling

suraj.sun recommends a CNet post giving details of a still little-known energy technology: the ground source heat pump or geo-exchange system. This is distinct from so-called geothermal energy, which taps the heat in the earth to provide energy. Geo-exchange is suitable in scale for small industry — the article describes one commercial re-development of an old mill into apartment and commercial space that put in a geo-exchange at about half the cost of traditional fossil fuel-based alternatives. Even some individual homeowners are opting for this green method of heating and cooling, at a premium in price of about 50 percent (but costs are very much per-project, largely because drilling is involved). "Rather than use underground heat, geothermal heat pumps attached to buildings capitalize on the steady temperature of the ground or deep water wells. In effect, they treat the Earth like a giant energy savings bank, depositing or withdrawing heat depending on the time of year. "

Comments

"little known" ???

[Gothmolly]

Ah yes, kdawson.

This technology is HARDLY little-known, but places where people need lots of heating and cooling (the Northeast) are also places where electricity is uber expensive (thank you Greenpeace), so heat pumps aren't worth the $$.

Re:"little known" ???

[Wandering Wombat]

Beat me to it.

I work in construction and land development in Western Canada, and every single project we work on uses geo-exchange systems, because we get huge tax incentives to utilize energy-efficient technologies (and as strata owners, we still get to charge standard amounts for utilities). This isn't a big city, and there's THREE places that offer geo-exchange services.

Maybe it's just "little known" where people "don't care".

Re:"little known" ???

[ach1lles]

Its been around since at least the 1940s. The building I live in (downtown Austin) uses it and it was built in 1938.

Re:"little known" ???

[Anonymous Coward]

Yup, I have seen houses built in 1970s that had these. Also they are being built nowadays more and more. I would estimate that every home builder knows about the technology. They opt in for air heat pumps instead because of the smaller sunk cost though. (Some of the new models work still well even in sub zero conditions.)

Re:"little known" ???

[JWSmythe]

    Actually, there are lots of people who have no idea that this can be done.

    I live in Florida, and very few people that I've spoken with know anything about it. I haven't been able to find anyone that installs it either, but I'm not looking so hard now that I don't own a house any more.

    There are quite a few interesting variations on this. I won't bother mention the well system, since that's what the article talks about. :)

    One was a dry system, where you simply needed a series of tubes (intentionally said for Sen. Stevens) buried in a horizontal plane at about 10' to 20' deep. You can pump a liquid for a heat exchanger, or even just air, to stabilize the air temperature at about 60F degrees. There are all kinds of options on this. A heat exchanger, or even circulating home air through have both been done successfully. Adding a small amount of outside air can raise or lower the temperature as needed. If 65F is too cold, say 10% outside air could raise that up to 75F.

    Another uses river or lake water. This would depend on your climate to if it would work really well. A friend of mine lives beside a lake that's between 20 to 30 feet deep. Her air conditioner also works very poorly. I introduced the idea of an open loop system, where it would pump water from the lake, through a coil and back to the lake. It would need some degree of large debris filtering, but not a lot (try not to suck up the Loch Ness monster). The coil at the house would simply recirculate just as the regular air handler in the house would, except the coils would maintain about 60 degrees because of the lake. When it's close to 100 degrees outside, and the lake water is in the high 60's at the bottom, a 75 to 80 degree house is a welcome temperature. :)

    Unfortunately, most people look at it as "but, everyone else has a .....". Some people were worried about a reduction in their resale value, because if they sell their home, now there's a "nonstandard" system there. Who would want a house with an almost free heating/cooling system?

    A freon free, low energy system, that takes advantage of the difference in air and ground/water temperature is a wonderful thing.

    This wasn't news, and I wanted to say so too, but people need to be exposed to the idea.

Re:"little known" ???

[artson]

When I built my house in 1985, I built a passive solar home (three sided, two-story concrete box with south facing glass and air conduits built into an insulated slab). We placed four solar hot water heaters on the roof as well. The house has repaid the investment many times over, but my one regret is that I allowed myself to be talked out of putting in a geo heat pump system. At the time the experts told me it was too expensive for the projected return. They were wrong of course.

I don't know much about accounting, but it has always seemed to me that carbon cap trading schemes are just a gigantic boondoggle that allow bad actors to continue acting badly. For my money, if governments (Canadian in my case) want to encourage green technology and lower the country's carbon footprint, then they need to very strongly encourage geo heat exchangers in new construction and particularly for green renovations. Solar heating is not always possible, especially this far north, but geothermal exchange is always there.

As a post script, for anyone thinking of installing solar hot water panels on their roof, think again. If it is possible to mount them at ground level on a rack, you achieve two things: A. no holes in your expensive roof, and B. it is much easier to maintain them at ground level.

Re:"little known" ???

[TheLink]

You could remove the need for debris filtering by having a closed loop at the cost of reduced efficiency.

For example you could fill a closed loop with water, and then put one end of the loop (with coils etc) in the lake, and then the other end of the loop either gets welded to the airconditioner coils (to help make the airconditioner more efficient), or is used as you suggest.

Of course you'd still have to clean the end stuck in the lake- stuff is likely to still grow on it.

Re:"little known" ???

[sribe]

The coil at the house would simply recirculate just as the regular air handler in the house would, except the coils would maintain about 60 degrees because of the lake. When it's close to 100 degrees outside, and the lake water is in the high 60's at the bottom, a 75 to 80 degree house is a welcome temperature.

60 degree coils would not even get you close to 75-80 in the house. Exchange efficiency, volume of air, number of BTUs coming in through roof & walls & windows & doors, yadda, yadaa. Not. Even Close.

Re:"little known" ???

[RandomChars]

Also in western Canada, the local university here uses river water for its cooling. Not really a geothermal situation I would guess, but still the same idea. I sort of wonder what the longterm effects of these sorts of practises will have on the environment down the road. Don't get me wrong, its probably way better than burning coal etc, but I still wonder.

Re:"little known" ???

[squoozer]

This technology is fairly well know in the UK and it's getting more popular everyday. The main problem with it is the cost of drilling (apparently it's about double the normal price at the moment because of the Olympic games - everyone that has a drill is down there laying foundations in Londons rubbish soil) as most people don't have enough garden to lay shallow pipe work. Longer term though if a lot of people switched to this technology we would need to upgrade the electricity grid.

Re:"little known" ???

[JWSmythe]

    Would we though?

    I don't know how it is there, but in the US an awful lot of people here run air conditioning, heating, and heatpumps (A/C that runs in reverse to make heat above 40F outside), that all run on electricity.

    There are some areas that do have a natural gas infrastructure, so they usually heat on that. I just haven't happened to live in too many.

    In the summer time, pretty much every building in the US has an air conditioner running, either central or a window unit (or sometimes both). There are exceptions to that too, but relatively few.

Re:"little known" ???

[deragon]

Since we are on the subject, Toronto did something similar at a larger scale:

http://www.toronto.ca/environment/initiatives/cooling.htm

Re:"little known" ???

[JWSmythe]

    That would all depend on the size of the heat exchanger, and the duty cycle.

    If, for the sake of argument, the typical duty cycle of a functional unit is 50% with say 12sq/ft of surface area on the evaporator, at 45 degrees at the evaporator. If you had 60 degrees at the evaporator, but increased the size to say 24 sq/ft, and the duty cycle to 90%+, it should be no problem. Consider that a system like this would require a pump similar to a swimming pool pump or smaller, which most people that have pools run for 12 hrs/day every day. A system like this wouldn't need to run at 90%+, but it would have that ability.

    In reality, it's not even required to run a pump on a system like this. There's a university (I can't remember who off-hand, but a big one) that is currently using a system exactly like this. They don't run pumps, the entire system relies on convection. The cooling itself is free, where the should have huge chillers, lots of freon, and huge power bills. They do still require power to run the fans for circulation inside the buildings, but that's it.

    For an ad-hoc system, I made the assumptions of double the size for the "evaporator", and one 1/2hp swimming pool style pond pump, that was able to handle small debris, with a bypass. If convection did it fine, then the pump was a waste. Even still, when I estimated the costs, and I am good at providing complete estimates, it was less than half the price of purchasing a new HVAC.

    But, your arguments are valid, and a good example of why people aren't willing to step away from what everyone else has. "Oh, that could never work."

    The same could be said of a Peltier/TEC based refrigerator for your car, yet they not only work, but people are very happy with them. Oddly enough, everything I've mentioned is not theory, but working proven fact, that has been implemented. Unfortunately, not widely, because people are afraid to change.

Re:"little known" ???

[JWSmythe]

    That's a beautiful example. And, they're still using the water for drinking, which is perfectly safe, since they're running it through a heat exchanger for the system, not using it directly. :)

Re:"little known" ???

[rasjani]

Maybe its the Euro thang ... you know, those pescy 's but here in Finland where we really do need need electricity for heating, we kinda use these to cut down the costs..

Re:"little known" ???

[jbengt]

Most A/C unit water coils (nit pick: there is no evaporator coil where you're using water cooled by the river or lake instead of DX) are designed on a dT (temperature difference) of around 10F to 15F between entering water temperature and leaving air temperature for practical reasons. That would mean a 60F entering water temperature would result in a leaving air temperature around 70F. This is not cold enough to do a significant amount of cooling, assuming that you're trying to maintain an indoor temperature of 5F or 10F higher. Getting a lower supply air temperature creates problems by requiring a lot of rows and fins, resulting in higher air pressure drops, and/or a lot of water being pumped through the coil. If you try to cool with the higher air temperatures, you end up needing a lot more air, which means even bigger coils, more fan power, and more water flow.
There's another, more important problem with using 60F water to cool the air (unless you're in a very dry climate). The minimum air supply temperature you can theoretically approach with 60F water is 60F, but you cannot dehumidify adequately without bringing the air down significantly below 60F.

Re:"little known" ???

[samkass]

I recall reading about someone in Hawaii doing something like this in order to both generate electricity and clean water by essentially using the deep ocean as the heat sink then the temperature differential to generate electricity (and the condensation for water). Apparently once you got the fluid moving it took less energy to pump it than you could generate with the heat differential in a tropical ocean island.

Re:"little known" ???

[gerf]

People in this area, Midwest, often build ponds when they build a new house in a rural area, and lay a closed loop in the bottom of the pond for heating/cooling. The only thing people need to be careful about is how deep things freeze, either in the pond or with the in-ground systems.

Re:"little known" ???

[Anonymous Coward]

I to live in Florida and have a ground water heat exchange system produced by ColdFlow. http://www.coldflow.com/
My system is old enough I don't need to used an enclosed loop. Nice thing about that is every time the unit is running my yard is getting watered too. These systems are very efficient and with being in a cinder block house my electric bill runs about $100 a month.

Re:"little known" ???

[Zadaz]

We've been getting virtually free heating and cooling on our 64,000 cubic foot storage building for 20 years. We simply ran a 30 foot extension from the drainage tile in the neighboring field and put a fan on the end of it. Constant 60f air. Paying electricity for a medium sized fan beats the hell out of $3,000+ heating bills in February when it gets and stays below zero or August when it gets above 100f.

If a farmer could hack this together from spare parts 20 years ago, I can only hope that the technology has gotten much better since then.

Re:"little known" ???

[budgenator]

That's probably 30-40 degrees cooler than the outside air the Air conditioner's evaporator coil is usually cooled by.

Re:"little known" ???

[Anonymous Coward]

I built a 4 unit condo building in Philadelphia and installed the first residential system in the downtown area. It will pay for itself in 4 years. We put out 70% less green house gases. And it seems that these condos sold a lot faster than the other new ones. Compared to the last place I lived, this one is twice as big and costs less than half as much to heat. Plus we don't turn down the heat at night (it's actually more efficient that way).

So Gothmolly, you are wrong and I have the numbers to prove it.

Re:"little known" ???

[JWSmythe]

  Well, when it's over 95 every day, 70 degree air wouldn't be bad. :)

  We have high humidity during the summer here, so it works out pretty well.

  Here's some weather stats for the area, as found on myweather.com (the first place I found with a Google search that showed them).  My apologies for the formatting.  You'll figure it out. :)

  If it could hold 70F at the coils, it would get us through the worst months (the summer), and provide cooling.  Outside of the summer, some people keep the windows open, until it gets hot (about 10am to 5pm daily)

Month Temp  Dew     Morning Afternoon
            Point    humid        humid
Jan        61F        49F        79%            57%
Feb        63F        52F        80%            56%
Mar        55F        68F        79%            54%
Apr        73F        58F        78%            51%
May        78F        64F        79%            51%
Jun        82F        70F        80%            58%
Jul        83F        71F        78%            59%
Aug        83F        72F        81%            61%
Sep        82F        70F        83%            60%
Oct        76F        64F        80%            55%
Nov        69F        59F        81%            58%
Dec        63F        52F        80%            58%

  I don't really agree with these stats, or more likely how they're being represented.  95F to 105F daily from late June through the end of August are the norm, not the exception.  That's also when you'll have a flood outside your A/C condensation drain. :)  A 2000+ sq/ft house will leave a small flooded area where it drains all summer.

  I want to implement such a system for a friend of mine. She doesn't have a lot of money, so most of the year she doesn't run heat or air.  In the summer, her house is typically 85F or so, with the windows open, and obviously the humidity isn't removed at all, unless you consider it being sucked into my clothes as removal. :)

Re:"little known" ???

[JWSmythe]

    Wow, a good AC post. :) Thanks!

    I don't see the unit you're referencing right off, but I'm pretty sure I know exactly what you're talking about.

   

Re:"little known" ???

[gpreach]

I can't see why anyone WOULDN"T want to isntall a geothermal system. Consider this: We live in a Canadian city called Winnipeg (http://en.wikipedia.org/wiki/Winnipeg) about 8 hours NW of Minneapolis. Most of our fellow Canucks call this place Winterpeg 'cause it's so freakin cold here in the winter. Our kids haven't been allowed outside at recess for the last month because it's been so cold. It's warmer at the North Pole. You get the idea. We put a geothermal system on our new house 2 years ago and it's been great. It keeps us at a toasty 23degrees C even if the outside temp is 40 degrees below zero Celsius ( same as -40 F) We have a 2-well system supplying a 5tonne heat pump. The house is well insulated from basement to attic which is key. It is incredibly cheap to run. There is a backup electric heater built in to the system, but it has only kicked in ONCE. In addition, it also pre-heats all of our hot water as a by-product. It really is the best thing going for heating and cooling your house, shop, office building etc...

Re:"little known" ???

[Phat_Tony]

Yeah, I grew up just outside of Columbus, OH, and our circa 1970 rural home had an electric heat pump, and a lot of our neighborhood did. I remember ads in Columbus with a little jingle "The Electric Heat Pump- It Heats, It Cools, and it Saves" airing on network TV and radio through the early 90's. Call up any HVAC contractor in the midwest and ask them what your options are for heating and cooling a new home installation, and they'll probably list heat pumps as an option. It's hardly obscure.

Most people probably don't know about it, the same way most people don't know anything about city water vs. well water, or what AWG wire or what amp circuit breakers are used in their household electrical wiring, or if their basement walls are cinder block or poured concrete, etc. etc. Most people don't know or care about these details of how their homes work, but that doesn't mean there's anything rare about heat pumps, there are millions of them installed all over going back 50 years or more, and they're still widely installed in new homes.

Re:"little known" ???

[lsatenstein]

Had a ground source heat pump/AC unit when I lived in Toronto. Three wells of 100 foot depths were drilled and thick wall hose was forced down and up each well, yielding about 600 feet of contact area to the hose. It worked well for about 2 years, first liberating the heat in the house to pre-heat the hot water tank, and in winter, using the excess heat to heat the hot water tank. Heating bills were about 50% of the next lowest cost alternative. In the spring of the third year, the ground shifted, pinching closed the thick walled hose. No more flow-- no more benefit, with the cost to repair being very high, as a drill rig would have to be brought in. It would work best where there is a stream of running water. Running streams usually get ice covered, but beneath the ice, water continues to flow, and thus there is good heat transfer to non-toxic hose with non-toxic antifreeze in it.

Re:"little known" ???

[aaarrrgggh]

NO. Ground source heat pumps take advantage of the fact that the ground temperature is fairly constant year-round (equal to average annual temperature). Since a heat pump is compressorized, it takes about 30% of the input energy to heat a space relative to resistance heating (above ground temp). That is thermodynamicslly comparable to burning oil, but with the benefit of the higher input temperature.

Heat pumps are only effective with cold-side temperatures over 40, which works for ground-source.

In the summer, the benefit is even higher.

Re:"little known" ???

[theshowmecanuck]

buried in a horizontal plane at about 10' to 20' deep.

This made me think of Winnipeg where I used to live. It gets so cold there in the winter they bury the water mains around 14 or 15 feet down to avoid frost heave. And then they still sometimes have breaks in the line. When it is 35 or 40 below zero (f or c... not much difference at that temperature) and water is bubbling up from the ground from a major water main... an ugly thing. I guess they can make the horizontal plane for those tubes another 20 feet deeper there. :)

Re:"little known" ???

[fermion]

electricity is uber expensive (thank you Greenpeace)

i am not sure how greenpeace makes energy expensive. This is supply and demand. If many people choose to move to an area where it is cold or very hot, and then build homes that are large and difficult to keep temperature controlled, then that is no fault except the idiots who do such things. Combine this with the upscale population who does not want power plants in the back yards, or coal or nuclear fuel moving through the area, then electricity is expensive. I don't think that 8 years of republican rule has been at the behest of greenpeace, yet we have no more nuclear reactors..

Something has to give. Either the people who can't afford the electricity should become fiscally conservative and stop buying stuff they can't afford, or allow the government to do what is necessary so that even people who are fiscally irresponsible can consume the huge amounts of energy they demand, subsidized by the fiscally responsible taxpayers.

Re:"little known" ???

[tylernt]

I recall reading about someone in Hawaii doing something like this in order to both generate electricity and clean water by essentially using the deep ocean as the heat sink then the temperature differential to generate electricity

Ah yes, OTEC. Has a somewhat high cost per kWh, but a neat technology in any case. You could even make a GTEC (same thing but with Ground instead of Ocean) power plant using a sufficiently large closed loop in soil, or a sufficiently large aquifer.

Re:"little known" ???

[JWSmythe]

    Ya, if the climate dictates, you'd have to make it deeper. :)

    I did a little more research on this today. I lost my old bookmarks (switching computers too much, and reinstalling for fun), so I don't have the good sites. I did find a couple pages on Wikipedia though. Search "Ground-coupled heat exchanger" and "Geothermal heat pump".

    I was talking to a friend in Alaska about this. A long time ago, I had read about setting up for the nuclear tests at Amchitka, Alaska. If I remember the details right, when they dug down to make the cavern, at about 100 feet, they were working in total darkness and effectively deaf due to the digging machine noises. The temperature was over 100 degrees due to geothermal activity. That's a long way from Anchorage though, even though both are geologically unstable (expect your pipes to break in the next earthquake). He took the opportunity to tell me about an earthquake in the 1964 that destroyed over 100 buildings in Anchorage. He noted one part of town that I drove through, that was a small valley, was flat land previous to 1964. :)

    I was trying to find how deep they'd have to go in the Anchorage area to find warm ground. I found the building codes dictate all underground water pipes must be 10 feet deep. My friend confirmed that, but said even at 10 feet, they have water pipe freezes and bursts in the winter.

    The purpose of that mental exercise was to find a way to warm a friend's cabin, in the middle of nowhere. The air temperature recently was 35F below zero, and that didn't account for the wind chill. Brrr. :)

    I found this page which they tested such a system, where the air temperature would reach 10F. They buried their pipes 4 feet deep, but ran electric heat for 4 months of the year. They should have gone deeper. :)

    I still haven't found a good answer for "how deep", but obviously 10 feet isn't enough in Anchorage. It probably requires a prolonged test with thermometers at different depths, to test the local conditions. I know soil composition makes a big difference too.

    Here in Florida, if you go too deep, you find ground water pretty easily. Water wells can be as shallow as just a few feet here. When I was a kid, we had a water well, that was dug into a cavern at just about 30 feet.

Re:"little known" ???

[Solandri]

It's a heckuva lot older than 20 years. The ancient Romans were using it to cool their homes. They even figured out a way to power it with solar power instead of a fan.

Re:"little known" ???

[Anonymous Coward]

I allowed myself to be talked out of putting in a geo heat pump system. At the time the experts told me it was too expensive for the projected return. They were wrong of course.

Why would you need a heat pump in a passive house?

Re:"little known" ???

[wrook]

For cold/hot days. The parent is Canadian, so sometimes you don't get enough sunlight to counter extremely frigid temps.

Also, geo heat pumps work great as air conditioners as well. Depending on how much thermal mass his house has, it might be quite hot in the summer.

Finally, you can rig them to help with hot water as well.

If I was building a new house, it would be my *first* option for heating/cooling. In fact, in my last house I needed to replace my furnace and if I wasn't moving in a few months I would have sprung for one. I remember getting a quote around the $10K range, which is fantastic given it's flexibility.

Re:"little known" ???

[LaskoVortex]

electricity is uber expensive (thank you Greenpeace)

You blame a bunch of hippies in blow-up boats on the expense of heating the northeast part of North America? I bet you also think that Bush and Cheney wired the WTC. Give me a break.

Re:"little known" ???

[commanderfoxtrot]

That's the first info I've seen on these implemented on a larger scale.

However- presumably the ground will heat up with these systems. If it's one house in a million, it won't be noticed. But say if all of London switched over, the ground might increase by a few degrees.

Does anyone know what effect this would have? We already have the "urban heat island" effect from lots of ACs and tarmac/concrete... this could just make it worse.

I've no idea if there would be an appreciable difference, but I haven't seen any analysis of it.

Re:"little known" ???

[tacocat]

This is a big cost savings and in northern regions typically come with a gas furnace backup for those really bad periods (sub zero?).

When I was replacing my 1950's furnace I looked into Ground sourced heat pumps and found that there used to be a very large incentive from the utility company to switch from electric to gas. But when the gas company purchased the electric company they dropped the incentive.

For my 1200 sq. ft. house it was a 100% increase in the installation costs ($20,000). This seems high overall, but I was gutting a 50 year old furnace and there was a lot of work to do. But the utility costs would have dropped from a $200/month high to a $30/month high. That implies 5.5 years to return the initial cost for Ground sourced heat. I was planning on moving about 2-3 years after installing the furnace and so decided it was not worth it. At this point I see no plans to move unless employment conditions require it. Ground Source would have been the better solution.

But so often it's just not worth the excess costs. A tax incentive would be great. It would especially help with electrical energy adoption since much of the load on gas would be mitigated

Re:"little known" ???

[yabos]

Yes that's called a pond loop in geothermal land. It works extremely well. The best part is looking out to the frozen pond and knowing you are heating your house with it.

Re:"little known" ???

[yabos]

I think it's highly doubtful that the electricity grid would need to be upgraded. Think of the demand in the summer due to A/C. It might be different in the UK but in North America there's a huge electricity draw due to A/C in the summer. Geothermal heat pumps are more efficient at cooling than an air to air(i.e. central air, or external air to air heat exchanger) A/C unit. Thus the demand for electricity in the summer would be lower than A/C if everyone was using geothermal exchange.

Re:"little known" ???

[Anonymous Coward]

I wouldn't say drilling is the main problem. You need to pump fluid around the sunken pipes and use a compressor/heat exchanger. My understanding is that for every 4KW you get out you need to put 1KW in to run the system. Also, assuming you want a heating/hot water system, the actual water doesn't get quite hot enough so you need some sort of backup. Couple this with the initial outlay, say £10,000 - £20,000 (UKPounds), sadly, it just doesn't make economic sense with current energy prices. If it did, I would have one installed because, as others have pointed out, it's not exactly new technology. There are also air based heat pumps as well.

Re:"little known" ???

[Fahrvergnuugen]

I thought closed loop combined with glycol (which can be brought below freezing) improved efficiency, not reduced it...

The electric pump can run less with a closed loop system because glycol has a greater temperature range. You're getting more heat per gallon per minute.

Or m

Re:"little known" ???

[squoozer]

Interesting, I know that when we were looking at getting ground source heating for our current house the first thing everyone asked up was "do you have a three phase electricity supply?". Fortunately we do but I that is seriously rare in this country and I can't believe it's all the common in the US either. Just connecting everyone to three phase would be a huge job in itself (similar in scope to giving everyone fibre internet connections).

Re:"little known" ???

[ben0207]

In the UK we just open a window.

Too hot? Open a window.
Too cold? Close the window.

Re:"little known" ???

[DwySteve]

Unfortunately, most people look at it as "but, everyone else has a .....". Some people were worried about a reduction in their resale value, because if they sell their home, now there's a "nonstandard" system there. Who would want a house with an almost free heating/cooling system?

Unless it's maintenance free or you can commit to providing me all the materials, tools, design documents, notes, know-how and contacts and find someone who will fix it for the same cost as a regular A/C unit when it breaks then yes, it is a matter of 'everyone else has a...' except that the sentence is finished with 'everyone else has an easy to maintain unit that 50 people in the phone book can fix for me.'

Oh, and I hope no one drains your lake, or your entire subdivision doesn't get the same idea about using the lake as a heat sink. Thermal pollution is still pollution.

Re:"little known" ???

[drinkypoo]

I live in Lake County, the most geothermally active place on the planet (at least, that's useful to man... ho ho ho) and there happens to be opportunity for a geothermal tap where I'm currently renting. You would have to go down about 80 feet. There's only one spot on the property. Here, you go about 120 feet to get to a clay cap over the aquifer. On the other hand, if you just go down 20 feet you get 50 degree temps. If you had a basement (not too common in California, I admit) you could just have the heads of heat pipes come out in your basement with some radiator fins on them, and allow passive air exchange with your house and get a major heat gain in the winter. In places where you need cooling, you can blow the air around in those months. How far down do you have to go there to get to 50 degree temps?

Re:"little known" ???

[drinkypoo]

It's a heckuva lot older than 20 years. The ancient Romans were using it to cool their homes. They even figured out a way to power it with solar power instead of a fan.

From the link:

8. The two other sides must be transparent, Plexiglas or some equivalent. Also, the higher/larger the chimney, the better.

Just out of curiosity, where did the Romans get their Plexiglas?

If you look in the book Barefoot Architecture you can see some examples of the chimney done a bit better. There is an internal partition and it has openings at the top to be oriented in the direction of prevailing winds. Even when there is no wind it will still work, but when there is some, it is much better.

Everything in that book isn't better; they completely boned the Savonius turbine (they used a central shaft, reducing efficiency by up to 80%) but in general there's a ton of good info there.

Re:"little known" ???

[LWATCDR]

Well in Florida a much more common system uses heat recovery to heat your hot water. Heating costs in south Florida are close to zero so you only really need to worry about cooling. Of course I did know somebody that did have one. The replaced it with a standard heat pump because of the cost. Their heat pump fried when somebody mowing the lawn hit the well head and put a crack in it.

Re:"little known" ???

[j79zlr]

I am an HVAC engineer and we do some LEED buildings as well as normal commercial work. I am relatively familiar with these systems and the main problem with ground source heat pumps are that the wells are very expensive to dig. For a large residential system, say 5-ton, the cost to dig the wells is somewhere around $20,000. If you put that in the upfront cost of a new house, maybe okay, but not too many homeowners are going to shell out $30,000 for a new furnace and a/c.

Also, the problem with heat pumps is capacity. You can use them with great effectiveness to heat in milder winter climates like the South, Florida is a good example, but if you tried one in say New York or Chicago [where I am], you will be running the supplemental electric or nat gas heat throughout most of the winter.

Re:"little known" ???

[drinkypoo]

Greenpeace is one of the biggest impediments to building new Nuclear plants in California where they are needed. Coal plants put more nuclear material into the air every year than all the nuclear tests and accidents EVER combined. I know a desk-rider and a former smokestack-climber in the pollution regulation industry and they both let me know in no uncertain terms that you can find people polluting over the EPA standards (whether those standards are even acceptable is a matter for debate) as fast as you can secure funding to send people up smokestacks. No joke. Meanwhile if we used breeder reactors (but try building a tried and true reactor, let alone something new) we could reduce our nuclear fuel consumption by a couple of orders of magnitude. Even a cofounder of Greenpeace has come out in favor of nuclear power, as he's realizing that moving to superior technology is more feasible than changing the consumption habits of the entire world. Unfortunately it is now far too late... Obama, meanwhile, is a Coal supporter. FWIW.

Re:"little known" ???

[j79zlr]

Ethylene and propylene glycol reduce the efficiency compared to a 100% water heat transfer fluid. The viscosity of the solution is raised [harder to pump] and the specific heat is lowered [heat capacity per volume]. A 50% EG & water solution system capacity has to be oversized by about 20% to have the same performance characteristics as 100% water and the pumps have to be increased to overcome the increased viscosity. In order to increase the delta T to reduce flow, you have to have a source and sink with a great differential temperature.

Re:"little known" ???

[j79zlr]

You still need the colder coil temperature to remove moisture. To maintain a maximum comfortable 50% RH at 75degF, you need a coil with a max water temperature of 62degF. Usually air comes off the cooling coil at 55degF and saturated [100%RH] so when it mixes with the air in the room, the resulting RH is about 30%. The moisture removal is arguably more important from a comfort standpoint.

Re:"little known" ???

[j79zlr]

Why would you need 3-phase power for a heat pump? What size HP are the pumps you have? I've never heard of a residence with 208V/3Ph unless it is Al Gore's house :p

Re:"little known" ???

[sribe]

That's probably 30-40 degrees cooler than the outside air the Air conditioner's evaporator coil is usually cooled by.

Yes, and if you used that water to cool the AC's evaporator coil, you would get a big boost in AC efficiency. However, that is not at all what the post proposed.

Re:"little known" ???

[moosesocks]

Most of Alaska is seismically active, so I imagine that you'd be spending lots of time repairing it every time there was a small quake. The 1964 earthquake was among the worst ever recorded.

Most of Alaska also has patches of permafrost, in which case you'd never get deep enough for it to be warm. Similarly, adding heat to frozen soil will cause it to shift, damaging any buildings that happen to be sitting on said soil.

Anchorage is also actually quite a bit warmer than the rest of Alaska, thanks to ocean currents. Its climate is said to be comparable to Chicago. (Several the northern US states actually had -30 temperatures last week!) Up toward Fairbanks, temperatures routinely go down to -50 or -60F (fortunately with very little wind).

The idea's nice, but I just don't think there's enough heat in Alaska to make such a system worthwhile, even ignoring the inherent reliability problems that will inevitably crop up due to seismic activity.

Re:"little known" ???

[squoozer]

Our house is fairly large by UK standards but by no means completely out of the ordinary. We have just fitted a 36kW gas boiler. To provide the same heating from a heat pump would about 12kW of electricity since heat pumps can achieve about 3:1 efficiency (note that acutally efficiency is usually more like 2:1 but we'll go with best case.

A modern UK supply is 240V on a 100A fuse which means it will provide up to 24kW of power so you could run a heat pump off it. Don't forget though the supply is also providing power to everything else in the house which could easily use up the other 12 kW especially if the cooker is electric.

I'm not very familiar with domestic wiring in the US but I'm guessing you typically have a main fuse of about 150 to 200A so that you can get the same power from the lower voltage. As you can see if the fuse is 150A it's going to be getting close the mark when it comes to supplying the heat pump and the house.

Re:"little known" ???

[fataugie]

When you say in the last paragraph, capacity is the problem...you're speaking mainly of regular, atmosphere heat pumps, correct? From what I understood about the ground loop systems was that the earth would maintain a constant mid 50's in temp. So it would allow the heapt pump to work as if it was a mid 50's atmosphere based system.

Am I wrong?

Re:"little known" ???

[fataugie]

OK, I could have made my first comment easier to understand...I apologize.

What I mean is, because the loop temp for the ground loop system would stay pretty close to mid 50's in temp...would that not be equivilant to an atmostphere based system where the outside air was in the mid 50's? Assuming each system is spec'd to the appropriate size for the heating and cooling load.

I'm planning on building a new house and am thinking seriously of a system like this.

Re:"little known" ???

[j79zlr]

US wiring is still 240V, it just two pole, not three. 240V hot to hot and each pole is 120V to neutral. At least here, you can't use 100% of the amperage, our codes limit that to 80%, so a typical 200A 240V house has 38kW of available power. A standard 5-ton (~18kW) heat pump does not use anymore electric than a normal 5-ton condensing unit, typically a 60A 2P breaker on 240V, that is why I was wondering why you needed 3-phase service.

Just a note, the efficiency of even very old boilers is about 60%, you can get new ones up to 88% non-condensing and up to 99% with condensing. The problem with heat pumps is that they just can't produce the heat, a 5-ton (18kW of cooling) heat pump can usually only produce about 35,000 Btu/h (10kW) of heat. The boiler you would have replaced, 36kW, even at 60% efficiency, is producing 22kW of heat, so you would still need auxiliary heat with the heat pump.

Re:"little known" ???

[j79zlr]

Yes, ground source water is usually deep and a constant 40-70 degF year round depending on your location. I would never use an open system, go closed loop with a heat exchanger and you can get great efficiency with a heat pump. They do work and they are very efficient. They just have to be sized properly and have the appropriate auxiliary heat to make up for the heat pump when it can't keep up. I would never use an open system, there is too much maintenance and if the water is not treated properly, it will destroy valves and piping rather quickly.

Re:"little known" ???

[Anonymous Coward]

Cornell University does this ... you can google the news articles.

Re:"little known" ???

[DuckDodgers]

Wikipedia says the UK summer average temperature in the warmest regions is 15.5 to 17.7 C (60-64 Fahrenheit).

Many areas in the US are significantly warmer. Telling someone to 'just open a window' doesn't work when it's 38 C (100 Fahrenheit) for 8 hours of the day or more, like most summer days in parts of Arizona.

Re:"little known" ???

[JWSmythe]

    I agree. It was a neat passing idea though.

    Last time I was up there, my friend pointed out the fact that his stairs had separated from the house by about a foot at the bottom (and still attached at the top). Either the bottom of the stairs slid one way, or the house slid the other way, or both. That was in the span of about 5 years.

    It reminds me why I'm happy not to be living in California. I love hurricanes. They're a lot of fun. Big rain storm, lots of wind. Sit around in a fairly safe building and have a nice party. Earthquakes are nasty. They sneak up on you, and knock you out of bed (or knock the house down on you).

Re:"little known" ???

[moosesocks]

There a whole bunch of houses in Fairbanks that were built on land that wasn't properly surveyed beforehand, and are all currently at 20Â angles relative to the ground.

Re:"little known" ???

[JWSmythe]

This is one of the articles that I had found before. Thanks for posting the name!

Re:"little known" ???

[Anonymous Coward]

well, i would suggest that you and your local community find a large parcel of unused, preferable already cleared land, and ask the local power company to build a nuclear power plant. The benefit is that large number of jobs will be created and probably excess power sold. A bond issue can be created to pay for the plant.

As far as waste the only problem is where to store. The technology already exists, for instance glass, and then just bury it in a geologically stable area. In all probability there is likely one in you area, so you can do this as well.

to be blunt, it is not good to always blame others when the problem is merely that we don't want to take our own junk.

Re:"little known" ???

[Muad'Dave]

My uncle had one of these systems in coastal NC 25 years ago! The laws then forbade him from putting water back into the ground (regardless that it had only traveled through clean piping), so he pumped the water through his system and used it to irrigate his garden. The water table was about 4-6 feet down, and he had essentially an endless supply of water (see map) that wasn't very good for drinking. He used to live in this geodesic dome.

Heat Pump

[conureman]

My dad has a couple exchangers outside his house I've often marveled at the "efficiency", particularly when they are covered in snow, or basking in the sun on a forty degree centigrade day.

Depends on the ground

[Anonymous Coward]

Be warned - this won't work well in all kinds of ground. We've had such a heating system installed in our 200m house about 20 years ago (Germany, with our oil prices we had to get creative a bit earlier than ppl in the US) and we had a lot of trouble with freezing probes (the things that go into the groud) because in the karst (ground with lots of lime in it and thus lots of small caves) they wouldn't keep proper contact with the earth.

Re:Depends on the ground

[Facetious]

Am I the only one who read that as 200 milliamp? For a moment I was astounded by the home's efficiency.

Re:Depends on the ground

[Anonymous Coward]

It was meant to mean 200 square meters...

Re:Depends on the ground

[Yvan256]

Slashdot, which is supposed to be run by nerds, still doesn't support UTF-8. Simply use HTML entities next time.

Re:Depends on the ground

[HisMother]

200 milli-Angstroms? That's a damn tiny house...

Re:Depends on the ground

[sokoban]

I tried to stop by his place, but since I knew its momentum exactly I couldn't find it.

Re:Depends on the ground

[rrohbeck]

Am I the only one who read that as 200 milliamp? For a moment I was astounded by the home's efficiency.

That just depends on the voltage you're using.

Re:Depends on the ground

[Brett Buck]

You are correct that it doesn't work as well in all kinds of ground, but we had one in rural Kentucky ~35 years ago, and it wasn't exactly unique in the area. Didn't even have to bury it very deep to get a reasonably constant 55 degree sink. And that's cave country - it's not exactly difficult to avoid sticking the heat exchanger in a cave!

          Brett

Re:Depends on the ground

[Anonymous Coward]

the preview shows you it the wrong display you know

Re:Depends on the ground

[Yvan256]

Yes it does. But that's still no excuse for Slashdot not supporting UTF-8. This is 2009, not 1999.

Done a lot around here

[Timo_UK]

Here in South Germany about 25% of the new houses built in our neighborhood have it. Old hat. If you use your garden as the storage medium your plants will flower later than your neighbor's....

Re:Done a lot around here

[srothroc]

So what happens when people all over the world start using it, since it's touted as being "environmentally safe"? Literal "global warming"?

Re:Done a lot around here

[nurb432]

Ya, its pretty common here too.

The story writer must live under a rock... no wait...

Re:Done a lot around here

[Rotaluclac]

My girlfriend and their neighbours (living in Germany) built this system for their houses too. In summer, heat from the Sun is stored directly underneath the houses. In winter, the hot soil is used to heat water and to heat the house itself. If soil temperature drops too much, a heat pump is used. That's of course powered by the photovoltaic cells on the roof. Rotaluclac

Re:Done a lot around here

[Kompressor]

And global cooling in the winter! O noes!

Then again, they might just balance out and leave the entire planet temperate...

Re:Done a lot around here

[Anonymous Coward]

Literal "global warming"?

Stop your trolling or get better informed. This just moves heat around, i.e. from the ground to your house. This is not the same as burning fossil fuels.

It's funny that most of the people who discount global warming and evolution and things like that are almost invariably the most ignorant uneducated people around. Coincidence, I don't think so.

Go crawl back to the bridge you came from troll.

What about DX?

[unixluv]

This technology has been around for some time, but it fails to generate much PR. You can get a measley $8000 US federal tax credit for installing one. A few enlightened states (not mine) will give you some additional tax credits for installing one.

The expensive part seems to be drilling the earth and laying the hose. However, what they fail to mention is that once its installed, it will last 50+ years.

The parent also mentions open and closed loop, but fail to talk about direct exchange aka DX, which would make more sense for a lot of people.

From http://www.geoenergyusa.com/technology.htm

"The direct exchange (DX) system is a series of copper tubes buried 4 to 6 feet below ground level. Refrigerant gas is then fed through these tubes creating a direct heat exchange between the temperature of the ground and the heat transfer medium, which in this case is the refrigerant gas. Because of this direct exchange feature these systems operate at considerably less operating cost than water source systems and because they do not require the additional water pumping cost and, DX does not suffer the heating or cooling loss associated with transferring the water temperature to the refrigerant as is common with these systems. DX is also cheaper and easier to install as it requires no well drilling or plumbing costs. As copper is a more efficient heat transfer medium than PVC pipe as found in water source, trenching costs are less due to less ground mass being required by DX."

http://www.youtube.com/watch?v=7CO_xM5gV48

http://www.youtube.com/watch?v=8P0Z1Pa_Vvc

Re:What about DX?

[unixluv]

Ooops... typo in above post... It should be $2000 USD.

Re:What about DX?

[Anonymous Coward]

Live in upstate NY - turned on our ground-source closed-loop heat pump end of November 2008. So far, so good.
Last year when we bought the system nobody was talking about DX (and in this neck of the woods, they're still not.)

Couple of things I would speculate about with respect to DX:
1 - copper pipe is MUCH more expensive than plastic geo-tubing and susceptible to oxidation and mechanical failure (e.g. you can punch a hole in a copper pipe pretty easily.)
2 - the refrigerant is likley NOT to be environmentally save (a closed-loop ground-source heat-pump system uses a 50/50 mix of food grade glycol and water - leaks are claimed not to have any environmental impact. The same cannot be said for most refrigerant gasses.
3 - I would expect the cost of install for a DX system to be higher than the ground-source closed-loop (as refrigerant costs more than glycol) so you'd want to factor that into your total cost and ROI calculations
4 - Residential installs can get a rebate in certain states as well (NY / California / not sure of the others). I think it maxes out at 2k or 3k. I'm not aware of a federal rebate for a non-commercial install (e.g. single-family home.)
5 - Ignorance expressed here: not sure if you can tie in the residential hot-water to a DX system (just don't know if they come with such a system tie-in available.) On our ground-source system, we ordered it with a built-in heat exchanger that heats our domestic hot water whenever the system is running. (Cuts your water-heating expense by 50~75%)

Hope this helps.
B.

Re:What about DX?

[rhakka]

DX systems suffer because they are burying copper in the ground (which is often aggressive to copper), and then pumping refrigerant through them. any puncture or breach would cause a leak of refrigerant instead of non toxic glycol solution.

DX and "Pump and Dump" geo-exchange systems are both, IMHO, likely to be outlawed in areas with environmental and building codes. Existing systems would probably be grandfathered but in the end I believe closed loop well or "slinky field" type systems will end up the winners.

Re:What about DX?

[kimvette]

How does the lifetime compare to PVC though? I've seen PVC that has been buried for 30 years and looks absolutely brand-new (the above-ground portions though - not so much thanks to UV). How does copper compare, since copper corrodes?

Re:What about DX?

[Anonymous Coward]

Copper won't make it a couple of decades below ground. Which is why no one uses copper below ground for things like water or gas supplies: it's all PVC or cast iron. Putting raw copper piping in the ground sounds like a supremely dumb idea.

Re:What about DX?

[Anonymous Coward]

Wouldn't you substitute du for dx and then antidifferentiate? Or do I just have calculus on the brain?

Re:What about DX?

[Anonymous Coward]

It's the coward from Upstate NY again...
Regarding closed-loop wells - water quality can present a significant problem. Water quality around here ranges from fabulous to hard to iron to hydrogen sulphide (sulphur water) due to deposits in the ground (most places that have natural gas wells have some kind of sulphides dissolved. Hydrogen sulphide gas ends up decomposing into a black powdery substance and sulphuric acid - which eats copper - supporting my previous post.) These are SIGNIFICANTLY corrosive (both to geo pumping and heat-transfer systems). Iron in the water can clog intakes and cause sludge build-up. All potentially detrimental to the lifetime of a system (hence my decision to go closed-loop rather than well-based.)
Final thought regarding "slinkys" is that they'll do if you don't have the space to run uncoiled. But if you have the space, I would pass on the slinky and get as much length to your system as possible. Slinkys are likely to be less efficient than a straight-run system if only due to the fact that a) there is less physical space in which to transfer heat from your system to the ground and b) the "crossing points" generated by the slinky design (where the pipes touch one another in the coil) are likely to make the system less efficient (as the heat or cool that is supposed to be transferred to the GROUND is instead transferred back into the pipe conveying the GeoThermal Fluid - aka gtf.

If I was to re-install my system today, rather than digging trenches and burying the plastic pipe, I'd dig a pond (8 feet / 3 meters plus deep) and simply toss slinkies into the bottom of it. A trench would still need to be dug from the house to the pond, but heat transfers between plastic and a fluid (the water in the pond) MUCH more efficiently than it does between the plastic pipe and dirt. Plus you get the benefit of convection currents of the fluid in the pond being able to take away either the heat or the cold from the lines.

Re:What about DX?

[rhakka]

closed loop wells don't use copper as the well sleeve, . they also don't replentish their water (that is why they are closed loop). right?

slinkies are not ideal... DX is, except for the breach and refrigerant issue. closed loop wells are 2nd though, AFAICT at least.

pond loop is interested, but submerging anything in water long term presents possible longevity issues as well.

Re:What about DX?

[unixluv]

Actually they have found underground copper piping used by the Egyptians thousands of years old. If copper was so fragile, there would be no copper to be found there.

Copper can be used underground and was used for many years for water supplies.

http://www.masterplumbers.com/plumbviews/1999/copper.asp

http://www.copper.com.au/cdc/article.asp?CID=58&AID=264

As noted in the articles, very few Ph and ground conditions can corrode copper, hence I object to the absolute ban of copper in the previous reply.

And yes copper is more expensive. But most plastics (PVC) cannot be used with refrigerants, so given a choice of metal pipes, copper makes sense in certain soil conditions.

With certain precautions, copper is the way to go in DX systems. I do agree with most of the above replies that closed loop is good too. I think that you have to weigh the intended use against the pros and cons, then select the best system for that application.

Re:What about DX?

[jbengt]

"Closed-loop wells" refers to an actual closed loop of piping, using double pipes with return bends at the bottom installed in well holes. Pumping well water up and using it directly,whether or not the well water was returned to the ground, would be known as an open loop, since the pipes are open at one (or both) end(s). Such open loops are almost never used anymore, due to environmental concerns about wasting water or returning possibly contaminated water to the underground source.

Re:What about DX?

[Anonymous Coward]

I worked for a utility contractor for a couple summers. The main water line for the subdivisions we were making were ductile iron. All the taps for each individual building were copper lines. Would think something besides copper would be used if it were cheaper or lasted longer since these lines are buried before things like roadways and sidewalks and foundations and such. Just me experience.

Re:What about DX?

[jbengt]

In the HVACR industry, "DX" stand for "Direct Expansion", The thing you're referring to needs a different abbreviation.

I know this system has been used, but there can be some problems with it.
Copper piping can have a short life in many soil types.
There will be more refrigerant in the system, which can add some complications and expense.
I wonder how they handle oil return when operating in the heat pump mode?

Re:What about DX?

[Anonymous Coward]

Copper doesn't just corrode from exposure to air or moisture. From one the articles you linked to yourself

"Since thermoplastics are non-conductors, they are immune to the electrolytic or galvanic corrosion that attacks and often destroys metal piping materials, particularly installed under ground."

I.e. copper can, and does, corrode quickly due to galvanic processes. It is also a rigid material and will not stand up well to the sort of movement and settling that soil experiences, especially ground which has been dug recently: for example, to lay copper pipe...

Re:What about DX?

[Anonymous Coward]

Bare copper pipes in earth are a definite no go, especially if they contain refrigerants. Better suited would be cupro-nickel (CuNi) which wouldn't corrode as quickly and is more up to the task of withstanding corrosion.

Re:What about DX?

[Anonymous Coward]

The solution to galvanic or electrolytic corrosion is well understood. Your comments, which are valid for a certain percentage of installations, are not absolute and should not generate a rigid ban on using copper.

Solutions:

1. Don't use dissimilar metals in direct contact with each other. So lay all copper and not a mix of copper and iron. There are also techniques to put sleeves on copper, which does reduce the heat transfer effectiveness a bit.

2. In really bad situations, use a sacrificial zinc electrode as they do on boats. This way the zinc corrodes and not the copper.

I really hate zealots (people which are sold on a single solution to the extreme of not considering others) not looking at the total engineering problem and whining how things can't be done. There are technical solutions to technical problems. Sometimes they are hard to solve and others less so.

Re:What about DX?

[Doc Ruby]

How do I find the NY state rebate on these ground heat pumps, independent of the Federal subsidy?

Re:What about DX?

[yabos]

You don't use PVC pipe. PVC is brittle. Closed loops use high density polyethylene pipe which is softer and more rugged.

Re:What about DX?

[yabos]

DX has problems in colder weather due to the refrigerant pooling in the U joint at the bottom of the hole. It is more efficient but it's also a lot easier to screw up as well. Since most installers don't have a lot of experience it's a lot easier to go with a regular plastic loop or open/well loops.

Ground source makes cents

[Anonymous Coward]

Consider that heat pumps give you on average 3 times more heating or cooling per unit of electricity over resistance heating, for example baseboard heating.

If you ignore the mindless Greenpeace types, and your power is from nukes (like in France) there are no greenhouse gas emissions at all and the air stays nice and clean. Likewise, if you live in the Northwest, where hydro makes a great deal of power and electricity is cheaper and cleaner yet.

One of the big problems with conventional heat pumps is that the coils can ice up in damp cold conditions, like the Northeast USA when temps are 35 degrees F and below. If you ground source, there is no defrost cycle needed, and no noisy fan. You have probably seen a heat pump at some point blow a huge ball of steam off on a cold day at some point, that's the defrost cycle.

Re:Ground source makes cents

[Malekin]

If you ignore the mindless Greenpeace types, and your power is from nukes (like in France) there are no greenhouse gas emissions at all and the air stays nice and clean.

Greenpeace are a bunch of nutjobs and the more base generation goes nuclear the better, but it's not totally greenhouse-gas-emission free. Mining the ore and enriching it generates GHG. The many, many tonnes of concrete that go into building the plants (~200 cubic metres per MW) generate GHG. Sure, it's the total GHG/kWh is less than just about any other technology, but it's not nothing.

Glad I live where electricity is cheap

[Anonymous Coward]

I'm glad I live where electricity is relatively cheap - in the southeast USA. We aren't as cheap as northern AL (hydroelectric), but our coal and nuclear plans have us near the bottom of the rate scale.

Combine that with natural gas for heating and underground utilities and my access to gas, electricity and water has been impacted more than 2 minutes a total of 3 times in 10 years. Water was shutoff for pipe work for about 6 hours - that was the longest impact. My gas and electric meters were replaced recently - about 20 minutes of impact.

Summer electric bills are around $130/month, but usually around $50 or less.

Winter heating is very tied to the temperature. Last month was $135, but it has been colder than normal this year. Perhaps another ice age is coming?

Water is always $17.23/month.

This is for a home about 2500 sq foot (3 bdr, 3 bath).

Reality Check

[Virtually Sane]

I got a quote from a UK company 2 years ago, some #1000 per KW of heating/cooling. Needless to say, there was no interest.

This was due to the compressors and pumps needed, there is also a high maintenance overhead as well

It is highly dependent on water movement through the soil structure, so putting one under a car park is a no-no.

More Articles

[bosef1]

The Washington Post had an recent article about this technology being applied in the Washington, DC, area. Slashdot has also featured articles on similar technologies that use deep water from large lakes or the oceans themselves.

Re:Will you please just leave the Earth alone?

[Anonymous Coward]

Just think of it as mother earth.

Since the article doesn't mention it...

[G-Man]

...I would also point out that Bush's Crawford Ranch uses a geothermal heat pump.

Re:Since the article doesn't mention it...

[ScrewMaster]

...I would also point out that Bush's Crawford Ranch [snopes.com] uses a geothermal heat pump.

Ah yes ... but does Al Gore's?

Re:Since the article doesn't mention it...

[sokoban]

Al Gore doesn't have a Crawford Ranch.

Re:Since the article doesn't mention it...

[ArcherB]

...I would also point out that Bush's Crawford Ranch uses a geothermal heat pump.

SHHHHHHHHH! You can't say anything at all good about the president. At least not until after inauguration day!

Seriously, I find it sad that we have an article about geothermal heating and cooling that is used by the private residence of the leader of the free world and it's not mentioned. Seriously, you'd think the article would have brought it up.

Has Bush Derangement Syndrome gotten so bad that saying anything good about Bush is taboo? Or was this a simple, innocent oversight?

Re:Since the article doesn't mention it...

[mapkinase]

That's the nature of humans. We generally do not give credit to bad people for their allegedly good actions.

Bush was a bad person.

Re:Since the article doesn't mention it...

[kauttapiste]

... the leader of the free world and it's not mentioned...

George, is that you?

Re:Since the article doesn't mention it...

[Dhalka226]

Has Bush Derangement Syndrome gotten so bad that saying anything good about Bush is taboo? Or was this a simple, innocent oversight?

Perhaps they simply didn't find it relevant. It certainly has no bearing on the pros or cons of such technology, and if they're trying to get the average person to consider such a system, telling them that somebody so rich they once owned a professional baseball team uses one isn't going to get it done either.

Honestly, they simply need to provide some sample numbers (obviously they'll vary depending on where you are and who installs, etc): The systems cost about $X, they cost about $Y per year to operate, you save about $Z dollars per year. If they're feeling extra helpful they can do the math for you and tell you where your break-even date is. That sort of thing is going to be much more helpful than whether or not George Bush owns one.

Re:Since the article doesn't mention it...

[MrKaos]

That's the nature of humans. We generally do not give credit to bad people for their allegedly good actions.

Hey, if the shoe fits...

Firsthand Minnesota experience

[Anonymous Coward]

I bought a house in Minnesota (cold winters, hot summers) that was a part of a pilot program in the 80s by Northern States Power (now Xcel Energy), whereby the installation cost was subsidized by NSP for this home and a handful of others.

Upon learning about this from the previous owners, I was naturally concerned about the system's efficacy at heating and moreover cooling the split-level home as compared to traditional gas furnace and air conditioning. It wound up performing identically on both counts, providing as much heated or frosty air as desired seasonally, all for only the price of operating the heat pump; I believe the annual electric cost was roughly $80/year.

To top things off the house was furnished with a traditional gas furnace as a safety backup.

Re:Firsthand Minnesota experience

[Solandri]

This is one of if not the best "green" energy solution I've run across. I first learned about it when doing cost calculations for HVAC systems for a new construction project in the low desert of California. By my calculations, in that location (hot summers, cold winters, large temperature shifts from day to night) it would've had a pay-back time of just 3 years, which is phenomenal. I don't understand why the environmental groups are not crowing about this to the extent they hype solar. It's available 24/7, does not require a clear view of the skies, has dramatically shorter pay-back time, is a low-tech solution which doesn't involve toxic manufacturing materials, is economical here and now instead of possibly in the future, and is viable over a much larger portion of the globe than solar. We should be putting them in almost every new house that's built.

Re:Can anyone say...

[Yvan256]

Permafrost.

What do I win?

Washinton County School District...

[gandhi_2]

...in Utah uses GSHP for almost every school. It saves them a grundel, but takes years to pay off.

Seriously though, burying your buildings or simply building them underground would be MUCH more efficient. Ammunition bunkers I used to go to in Hawaii or now in Utah were always cool in the summer and kinda warm in the winter. And hella insulated.

Re:Washinton County School District...

[ScrewMaster]

...in Utah uses GSHP for almost every school. It saves them a grundel, but takes years to pay off.

What is a grundel, and why would you want to save it?

Re:Washinton County School District...

[Anonymous Coward]

...in Utah uses GSHP for almost every school. It saves them a grundel, but takes years to pay off.

What is a grundel, and why would you want to save it?

Considering the Google results for the word, Ganhi_2's explanation for the term could provide some informative amusement in regards to their bundled thoughts at the time they used "grundel" in their comment.

Re:Washinton County School District...

[navyjeff]

What is a grundel, and why would you want to save it?

A grundel is an Old English bipedal monster or dragon, descended from Cain. I would imagine you would want to save it for yourself in order to keep your neighbor's dog off your lawn.

Re:Washinton County School District...

[gandhi_2]

The dragon also keeps the kids away from the GSHP equipment which is near the playground.

Re:Washinton County School District...

[Anonymous Coward]

bunkers I used to go to in Hawaii or now in Utah

Are you hiding out in the bunker because of the anti-prop 8 nuts?? Good idea.

Absolutely

[Swordopolis]

My parents built a new house off the beaten path almost 4 years ago, and opted to go with geo-exchange because natural gas isn't available in their area. The system costs significantly more than a standard one, but heating and cooling costs are HALF of what they were at their old house, which was significantly smaller. According to some back-of-the-napkin numbers my dad crunched, they should hit the break-even point after less than 15 years of use.

Common in Finland

[AliasMarlowe]

They are also quite common in Finland. Usually, a network of pipes is laid about 2 meters below ground level in the garden as the thermal reservoir (in less extreme climates, one meter deep may be enough). They have higher capital cost than the air-to-air heat pumps, but generate less noise and continue to operate even in very cold weather - unlike most air-to-air units, which get into trouble below -20C.

Re:Common in Finland

[Gordonjcp]

They're becoming more common in Scotland too. We have relatively cheap electricity provided by wind, hydroelectric or nuclear power stations, and we've got the space to spread these things out. They work, too. In Scotland's mild climate (never much colder than 10C, never much hotter than 20C) they work pretty well.

We can store carbon dioxide and use this idea.

[Burneypmcgillroy]

Humans can get some of that extra carbon dioxide we billow out and make a whole new industry for the idle factories and my fellow Americans. http://www.r744.com/papers.view.php?Id=559 This is easy stuff and the payoff is less energy to modify temperature and humidity in homes for our human happiness.

I wanted to

[JediTrainer]

Recently we installed a new furnace (Ontario, Canada). My wife and I had it priced out.

Turns out that although there were several grants we could receive, totalling $7000 approximately, it was still not worth it.

By the time all was said and done, it would have cost $30k to install. They would have torn up our lawn, which would have necessitated new landscaping. They also couldn't guarantee that they wouldn't crush our water and sewage lines with the drilling trucks.

All in all, it wasn't 50% more expensive. After rebates, it would have been about 4 or 5 times what a 96% efficiency natural gas furnace cost us.

Re:I wanted to

[Zerth]

Only 5 times the cost?

How much cheaper was the yearly operating costs? 5x install sounds like it could pay off in just 5-10 years.

Re:I wanted to

[ducomputergeek]

From everything I've head read or heard, going with a DX system makes a lot of sense if you are building new construction. It is easier to install without having to worry about the before mentioned problems of hitting existing pipes and landscaping. But for existing home construction, it's questionable.

Some day when I do build a house, the two things I want are a DX heating/cooling system and solar panels. Lump those costs in the home and use the extra money from what would have been spent on utilities to pay down the mortgage faster. Of course, if you're married, it may go towards the Mrs. shoe and purse fund instead....grumble, grumble...

Re:I wanted to

[Anonymous Coward]

I'm in Vancouver - Canada. I was interested in doing it too but the company I got a quote from said it was gonna be $40k (plus they said I needed a gas furnace anyways as the efficiency level drops when temperatures reach extreme ends of the scale in winter). The gas furnace I went with was only $8k. I was already over budget on my house at that point because of the increased costs in labour skyrocketing with the exuberant house prices so I just couldn't afford it regardless of how green I wanted to make my place. Nice old technology but because fossil fuels are much cheaper at this moment its not worth it.

Re:I wanted to

[dieman]

Exactly. I did a 'hybrid' air source geothermal/gas system and it was still at least 3 to 4 times cheaper. I will make up the cost of the air source heat pump in 4 or 5 years, easy, too. Plus I reduced my GHG by about 30% using 'green' power purchases for the heat pump power. This is in Minneapolis too, no slouch to cold temperatures. All the AHSP needed was a little more space, not an entire tear-out of a section of my yard. I'd love to do geothermal, but its really not a solution for people just trying to fix their dead furnace on an emergency (its dead jim) basis.

Re:I wanted to

[jern]

Yeah, I know the rebate your talking about 8000.00 CDN sounds like a lot of money when you take into account the payback of the system.

Also, what the Ontario/Cdn Gov't wont tell you is that you have to bring up the REST of your home (Read: insulation upgrades EVERYWHERE!) in order to get the 8k

Re:I wanted to

[Ralph Spoilsport]

Fat lot of good that gas furnace is going to do for you when the Energy Return on Energy Invested of gas production in Canada goes below 1:1 in 2014 and production collapses.

rs

Re:I wanted to

[wrook]

That's really strange. A few years ago I got a quote in Ottawa for $10K. As others have mentioned, a lot depends on the circumstances. In my case, there was no problem getting a backhoe in and I could run an open system, so it definitely cuts back on cost.

But I still wonder about $30K. Seems quite expensive to me.

Re:I wanted to

[yabos]

If you got a quote for $10K it is purely based on an open loop. Drilling holes in the ground usually costs $10K or more by itself because the drillers charge around $10-$12/foot. This went up a lot due to the higher fuel costs and still hasn't come down much like everything else.

The geothermal heat pump itself usually will not cost much more than a high efficiency top end gas furnace. The extra cost is the drilling/digging, labour and duct work changes required. Geothermal requires moving more air over the coils which usually means you need to upgrade your ductwork trunks to larger sizes.

Re:I wanted to

[swatthatfly]

Same thing in Montreal. I had my mind set to change my old oil/electric furnace and heat pump with a geothermal system. The total price after federal and provincial rebates was over 3 times more expensive than other "regular" systems. We calculated that you need 14 years to break even, and start to save any money in heating/AC cost. Not worth for us.

Re:I wanted to

[CmdrPorno]

The cost-benefit is the same way in the States. On the other hand, a traditional air-source heat pump costs about the same as a regular air conditioner, and is much cheaper than heating with gas or resistance heat. (When the outside air temperature gets too low, the less efficient backup heat--gas or electric--kicks in.) The systems that have gas auxiliary heat are commonly called dual-fuel or hybrid heat.

Re:I wanted to

[JediTrainer]

How much cheaper was the yearly operating costs? 5x install sounds like it could pay off in just 5-10 years.

Not enough to make up the difference. We put in a 96% eff. furnace instead. We figured that compared to its operating cost, even if the geothermal system took it down to 0 it would have been more than 15 years to pay off. Which coincidentally was the length of the warranty on the piping.

This idea doesn't work worth squat ...

[ScrewMaster]

Tapping the Earth For Home Heating and Cooling

I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

Re:This idea doesn't work worth squat ...

[CarpetShark]

I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

This is why you should leave it to the professionals. I bet you just went ahead and arrogantly acted like an expert without even buying a proper pair of tap shoes.

Re:This idea doesn't work worth squat ...

[ScrewMaster]

I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

This is why you should leave it to the professionals. I bet you just went ahead and arrogantly acted like an expert without even buying a proper pair of tap shoes.

No, I just figured the ground would warm up when I tapped it.

Crawfish ranch

[Anonymous Coward]

"I fondly remember ranching crawfish on my father's farm in Virginia."

Al Gore, "An Inconvenient Truth", 2006

I have one.

[haeger]

About a year ago we installed one of these in our house. The temperature around here varies between -15 C to about +30 C (get with the metric program people) and our heatpump is working wonders with our heating and economy. It cut the costs down to 1/3 of what it used to be and will have paid itself off in less than 5 years with current prices.
We drilled about 200m down which gives the best performance for the size of our house.
Also we put a large watertank that the heatpump warms up which increases the lifespan of the pump and our next project is to put solar panels that will heat the watertank during mars-oct, thereby increasing the savings even more. It will also "reload" the hole/well that the heatpump takes its heat from increasing the efficiency during winter.
Now if I could only produce electricity somehow to power the heatpump (or parts of it) things would be awsome.

I'm amazed that more people don't use this technology. In my opinion there shouldn't be an energy crisis anywhere as all the technology we need to fix things are already availible. More or less anyway.

Haeger

Re:I have one.

[Fallingcow]

I'm amazed that more people don't use this technology.

Like most things, it's not for everyone.

Our quote for installation here was about $25,000 for a system that would heat/cool a 3000sqft house.

The house cost us less than $100,000, and we probably won't be here more than 3 years or so. No way in hell the house's value will be increased by at least the difference between our savings and the remaining cost of installation when we sell. Conclusion: we would lose money putting in that system.

It's sad, but unless these kinds of improvements become more highly-valued by home buyers or people stop being so damn mobile, for many of us it's just not worth it to make long-term energy efficiency investments in our houses.

Re:I have one.

[Anonymous Coward]

I am backing off a little on my comment "metric in name only" - this is due to the link to some other units that are indeed metric due mainly to Lord Kelvin (sidenote, metric lovers ought to dump Celsius and just stick to Kelvins - you know, to promote your less units is better and foolish consistency philosophy). I still think Celsius sucks. Its 'granularity' (20 C versus 21 C) does not match that of Fahrenheit (70 F versus 71 F). Picky, yes.

Here is a good link.

Re:I have one.

[TrailerTrash]

I have one too, a retrofit on my existing house. It eliminated the external (and massively undersized) air conditioning unit, and runs much more quietly than the gas system did. And the gas system was only 6 years old when I replaced it, so it wasn't a dinosaur.

One piece of cool tech I haven't seen mentioned directly is that the heat pump itself creates heat; this is siphoned off by a water-based heat recovery system into a secondary hot water tank. When the primary hot water tank needs input water, it gets the heat-boosted water drawn off of the waste heat recovery system, making the whole thing more efficient.

The utility is pushing the use of geo so hard that they installed a second service into the house, and any electricity flowing through that meter is 1/3 the cost of regular electricity.

New neighborhoods in the area are all being built with geo in it from day one.

Re:I have one.

[jfanning]

We investigated one here in Finland when we built our house four years ago. They were starting to become very popular about that time since electricity prices just keep going up.

But in any event we were advised not to go that way since the investment would be too large for a house our size (total room area of 130 sq metres).

So we have a air exchange system that heats the incoming air using the outgoing air. It is mandatory in Finland that all new houses have a total air exchange approximately every two hours, so the HVAC system uses the waste heat to both heat the air and any excess heats water (for example extra heat from the bathrooms, sauna or fireplace). The system provides hot water for the underfloor heating as well. That should cut the total power consumption for heating by about 30%.

Re:I have one.

[Doc Ruby]

How much did digging the 200m (really that deep?) well cost? Is it linear in cost per foot?

Re:I have one.

[Doc Ruby]

How much per foot deep to drill the well?

Re:I have one.

[haeger]

They drilled so not much digging required. The price depends on a few things like how fast they hit rock (earlier is better) and other things. I think we paid about $2000 but I'm not sure. Around there anyway.

Haeger

it's the future (and now)

[Anonymous Coward]

Near me, many people already have wells and they use propane to heat (big $). Huge savings for them if they have a place to dispose of the exit water.

If you have natural gas available and don't have a well, then it might not be the best deal.

Ground source heat pumps are least 3x more efficient than electric and with the right design, can go as high as 6x more efficient.

Check out the Goethermal Heat Pump Consortium

[InterGuru]

The Goethermal Heat Pump Consortium is an industry group. Their site is full of information resources, blogs,and forums.

Bookwormhole.net -- over 7500 published book reviews.

The good news is that you are SO wrong

[WindBourne]

The heat pump that you are talking about has the condensor in the air. That is a horrible choice because yes, parts of the east (and midwest) can hit -40F (or C). If you are heating to say 70F, then you are looking at 110F difference (or ~50C). That IS inefficient and you are better off just doing straight heat from electricity.

But a geo-thermal HVAC is different. The condensor is piping that is 5-10' down in the ground. The temps are around 55-60F. IOW, you are pulling with maybe 18F/5C range. That is EXTREMELY efficient. In fact, if American were on these, our cooling in the summer would use something like 25% less electricity and our heat bill for the majority of the US would be a fraction of what it is. Even here in Colorado, a front range home who spends 150 for gas heating (a cold month) would expect to only pay about 50-60 for the heating.

One of the nice things about this, is most of the east coast's fuel oil actually comes from Venezula. If the east coaster would switch to this, we would see our imports from Venezuela drop to about 1/4 to 1/3 of the current amount (Venezuela oil is apparently low grade with lots of sulfur in it; pretty much used for diesel and home heating oil). BTW, EU makes heavy use of Russian natural gas for heating (which is why these games come into being during these times). The best thing that the west can do is move homes to geo-thermal and for American insulate better.

Re:The good news is that you are SO wrong

[petermgreen]

BTW, EU makes heavy use of Russian natural gas for heating
And for electricity generation which means we get hit with a double whammy when the gas supplies are disrupted.

Lukilly afaict our supplies in the UK come as LNG so we brits have avoided the affects of russias squables wit it's neighbours (though if there was a cold war 2 we would really be in the shit).

Re:The good news is that you are SO wrong

[Anonymous Coward]

You've got it backwards wrt efficiency. Heat pumps are more efficient with a larger temperature differential (check any decent thremodynamics textbook). However, they take a *lot* more energy to operate that way (so much so that at some point they stop operating and heating is switched to a resistance heater).

Running a heat pump from a ground source instead of air, in winter for example, means that it will operate less efficiently due to a smaller temp difference. However, it takes a lot less energy.

So while ground-source heat pumps are less efficient, they are more cost effective in terms of energy use.

ground-exchange? the price tag hurts...

[chrispitude]

Side note to the OP, the phrase "geothermal" to most homeowners does mean ground-source heat pump technology, not the stuff they use in Greenland.

I have a modest 2000sqft home in northeastern PA (Poconos area, I'm 8 miles south of Camelback ski resort). I had two contractors out to quote ground-source DX (direct exchange) systems, and both quotes were in the mid-$20k range. Too rich for my blood.

I went with a Hallowell cold-weather heat pump for pleasantly less than half that. The Hallowell is mostly sold in Canada and upper New England, but it's been slowly working its way south. When I called them to ask about my application, the guy laughed and said "Man, you're in the tropics!"

It's only been running for a few weeks now, but I've been very impressed so far. It hit -3F two nights ago and the heat pump still ran entirely off the first compressors in stage 1 (stage 2 was still not needed). The air coming out of the vents was warm to the touch. In fact, the system has yet to resort to resistance heat down to -3F exterior temperatures. We keep our house set to 66F. I've been able to kick the heating oil furnace and storage tank to the curb. No more timing oil pre-buys against market prices, no more noisy power venters, no more oil storage tank taking up basement space, no more yearly burner tuneups and vent pipe cleanouts. I even get nice 18 SEER air conditioning to replace my builder-grade central air conditioning unit.

Pictures of the complete home renovation are at:

my house renovation

The entire system is on a dedicated subpanel, and I've put a subpanel meter on it to measure total kWh usage. This will allow me to directly measure operational cost each month.

Another factor that steered me away from ground-source is balancing the break-even time versus the system lifetime. If it takes me 20 years to break even on the ground-source and the system needs replaced not too long after, I haven't really gained anything. If the Hallowell takes me 7 years to break even and the system lasts 2-3 times longer than that, I've saved quite a bit of money. Break-even isn't everything; it has to be balanced against the expected lifetime of the system. Plus, I'd have to factor in the cost of repairing the yard after the loops were dug and installed. They claim that just a 3' circle of ground is disturbed to drill the loops, but one of the guys eventually admitted the machines rip up the yard pretty bad as they drive around the hole to drill the loops at different angles.

I found the guys at Hallowell to be very helpful to talk to. I don't work for them and I have nothing to gain. I simply speak as a satisfied customer. For new construction, rolling a ground-source system into the mortgage would be the way to go. For my existing construction with an established yard, simply setting the Hallowell on an outdoor pad was an excellent path forward for me.

- Chris

"so-called geothermal energy"

[minsk]

Any idea what would motivate someone to add a "so-called" to geothermal in the summary? It's used following its so-called "definition", and is certainly a more so-called "established" term than the so-called "geo-exchange"...

Unintended consequences?

[Nimey]

I can't help but wonder about what would happen if a sufficient number of people in an area used heat pumps, long term.

What would happen if the ground got abnormally warm? Would this cause any problems with ground strength, or soil moisture, or what have you?

I'm genuinely curious here. Has anyone done a study about this?

Re:Unintended consequences?

[DamonHD]

Hi,

Have a look at http://www.withouthotair.com/ where Prof MacKay deals with this.

In practice you can mitigate the problem (which will only be a problem at all in dense population areas) by capturing solar heat in summer, eg excess not needed for solar hot water, and using that to warm the ground. Then the ground is a straight-forward heat-store, maybe a little like this: http://www.earth.org.uk/milk-tanker-thermal-store.html

Rgds

Damon

Re:Unintended consequences?

[jbengt]

When designing the ground-coupled heat pump system, you need to balance the heat gained by the ground in the summer with the heat removed from the ground in the winter. Where they don't balance out, you need to figure that the ground will warm-up (or cool down) over time, and you'll need more heat exchange piping in the ground.
You're not really adding and removing any more heat to the ground than you would add and remove from the air, only a little less waste heat due to better efficiencies. Since the heat flux from the center of the earth comes from much higher temperatures, and flows to a big range of climates, there should be no noticeable overall impact on the underground temperatures, except locally. Local temperature differences would not be great except where a high density is installed, like could happen in urban environments.
Of course, like anything, if this becomes the standard way for 10 billion people to heat and cool their houses, offices, etc., it will have an impact that needs to be controlled.

Re:Unintended consequences?

[djcmackay]

I can't help but wonder about what would happen if a sufficient number of people in an area used heat pumps, long term.

This is one of the questions I address in my book, Sustainable Energy - without the hot air (available from amazon, and for free (pdf) on the web). The chapter on "Smart Heating" highlights heat pumps. They are definitely going to be one of the pillars of the post-fossil-fuel future. With a typical suburban population density, there is indeed not enough ground area for everyone to get all their heating out of the ground, if they are not careful to put heat back at other times of year. If people suck too much heat, without putting it back, then the ground will gradually become frozen. There is a similar potential problem with ground source air-conditioning, where people use the heat pump the other way round a lot, dumping heat in the ground (or sucking cold, if you like). Eventually the ground warms up, and the A/C doesn't work so well. This has happened in central London. There are two fixes: (1) ensure that annual heat sucking matches annual heat dumping (by matching winter heating to summer A/C, and perhaps even adding solar hot water panels to the roof, to get extra heat to dump during the summer); or (2) use a heat pump but with a different heat source, for example the air. As already noted, air-source heat pumps are not great if you have -40 degree winters. But in many countries with mild winters (eg Britain) I think air-source heat pumps are the best choice for green heating. Sustainable Energy - without the hot air also has an appendix on heat pumps in which the relevant equations are worked out from first principles. David MacKay Cambridge

little store

[zogger]

A family I know with a little country store do their cooling in the summer with such a system, All home made and really easy. It uses an old window AC unit modified to use liquids with a few new plumbing pieces. They just pump cold creek water through it, then it goes back to the stream. Works perfectly.

Re:little store

[JWSmythe]

    I don't suppose you'd have the opportunity to take some pictures, and diagram it for me, would you? :)

    You can make an initial contact to me through the form on my site. I'll respond from my regular email account.

Geothermal pays if you can't get Natural Gas

[knobsturner_me]

Colder climates - If you can't get Natural Gas, then you are stuck with Propane, Heating oil, or electric. Heat pumps usually produce about 3x - 5x the energy that you put into them. Work best with heated floors. Unfortunately the installers have been installing oversized systems - it is best to make one that can't keep up on 10% of January days, and supplement with propane on those days. We stopped using approx 1ton propane/month for the winter big three months - which is about a 15 ton CO2 reduction for the house per year. Also air conditioning is just about free. Almost all buildings use it in some places in the mountains. (Propane is very expensive on a mountain). Nat gas costs 1/3 that of Propane, oil or electric.

Re:ground-exchange? the price tag hurts...

[Buelldozer]

I'm in Central Wyoming and I'm interested in something like this but I'm also tinkering around with various 'get off the grid' projects and I'm curious how much power generation I'd have to install in order to run one of these.

So, if you feel like sharing, what exactly is your kWh usage?

Location, location, location

[EmbeddedJanitor]

It all depends on where you live. I live in an area that was once old river bed and there is a lot of water movement through the old gravels just 5-10 metres below the surface. For me, drilling to 20 metres would be almost as good as placing the heat exchanger in the river.

mental diagram

[zogger]

I don't live in that area anymore and didn't take pictures, but I think you can get it with this mental diagram. It's easy, Just a cheap plug in water pump and they use the existing coil and the squirrel cage blower. You'll need to use adapters to match the sizes on the coil. I guess you could use like a cheap/small used swimming pool pump, I didn't see what they were using, they just said a "water pump", sitting on a little shelf alongside the AC unit in a box. It was remarkably simple. I didn't even pick up on it until I visited their store a few times (normal cool inside like it had regular AC running, small little store) and noticed the water pipelines dropping down from the back of the unit (you could see it from the parking lot), so I went over and checked it out, then asked them about it. The guy who owned the store just took the old AC when it died and modded it. The creek is around 40 or so feet away, runs year round, little trout stream in north georgia mountains, so it is more or less pretty cold even in the summer months. They just drain it in the winter.

Thinking about it, you could build one with a car radiator and a box fan (measure window to get sizes where you need to put it), same deal, just add the pump, then maybe a little sheet metal shroud to tidy it up so it looked good. I've been meaning to build one myself, we don't use AC here, but I water the garden so much with cold well water that I keep thinking..hmmm..might as well. Just anther project, and I was going to put an underground tap out there anyway to eliminate hundreds of feet of garden hose out on the ground.

Re:mental diagram

[JWSmythe]

    That was my general idea (I've had a few) for building one with available parts, instead of making lots of custom stuff.

    A 4-core radiator for say an old fullsize Chevy truck or Cadillac would work well. Those trucks generate a lot of heat, because they're usually geared for towing, or moving lots of weight. We had a '79 Chevy crew cab, that could only do about 70mph because it was geared to tow a 5th wheel trailer. :) At one point the radiator went, and I threw one in from an old Cadillac (because it was handy), which was also almost the same size.

    I'll probably build hers to cool one room, appearing to be a window unit. If she goes to do the full house, cascade several of these radiators together, and increase the volume of water pumped. And yes, a pretty box to go around it. :)

    I did find some commercial units, that were laid out kind of weird, with the inlet air at the bottom, and the outlet on the side. To build one, the easiest would be to literally build a square box. The radiator would be perpendicular to the house. Both inlet and exhaust would be on the same side, one in each half of the unit. A little weatherstripping around the radiator, and you'd have a good seal where the air could only go through the radiator.

Re:mental diagram

[drinkypoo]

I figure the place to put the radiator is inside the house. Radiators do have the problem that they leak, and often. But you want cooling to be up high where the air falls, so perhaps you could put it above the window and incorporate a gutter into the enclosure? It seems a shame to blow a window on this. Ideally in a whole-house situation you'd have a stack of radiators, water going into the last first, inside a well-drained box feeding your central air. Put it onto the inlet side of the furnace so you can use its blower, and you need a door system (louvers?) to switch it into the system when you want to cool the intake air. Draw from the cool side of the house... But of course, that only helps if you already have central heat. I have a swamp cooler installed in the least-useful window in the house, and it does an acceptable job of cooling. The efficiency is probably an order of magnitude higher than what you'll get with a radiator because it's a phase-change cooler. But it does make things a little muggy and it won't work in the land of humidity anyway :)

Can be done on larger scales, using old mines...

[PhotoGuy]

This can be done on larger scales, using old coal mines that have been flooded with water. At depth, the water is fairly constant, and the volume of water is large enough, that it can be used as a sink for heat pumps. Here in Nova Scotia, Springhill uses old coal mines to help with heating. From wiki:

The abrupt end of the coal mining industry presented incredible economic challenges to the town. An unexpected legacy and benefit from the closed mines is being realized in geothermal energy. The mines in Springhill were among the deepest in the world at over 14,000 feet below the surface. Since their closure, the mines have filled with ground water which is heated to an average temperature of 18 C (65F) by the surrounding earth. Beginning in the late 1980s, this heat source has been exploited by companies located in Springhill's industrial park, situated on the land where the surface facilities of the coal mines were located, reducing winter heating bills substantially.

Note that this isn't using hot steam deposits as a free geothermal heat source, like much of Iceland. It's simply using the water in the mines as part of a huge geothermal heat pump. A subtle, but important difference. (The former is a greater source of "free heat", whereas the latter still requires heat exchange like a residential heat pump.)

Re:ground-exchange? the price tag hurts...

[Anonymous Coward]

So explain this, why am I to trust a company that clams 300% efficiency? And a 5 year warranty?? I thought 10 or more is the standard, what is wrong that they can't support a longer warranty? Too much magic talk in there ads.

Re:Can be done on larger scales, using old mines..

[PhotoGuy]

In bad form, I'll reply to my own post to add a bit more info:

The difference between the geothermal heat source, and a geothermal heat pump is this: the underground temperatures are not high enough to provide your heating (they're typically 65'F or so, I believe). Pumping 65'F water through your house (after losses along the way) isn't going to do much for you.

But because it is a constant temperature, you can use a heat pump, with refrigerant, a compressor, evaporator, etc., to extract the heat from it. What you get is heat in your house, and a by-product of chilled water, which you pump back into the ground (and is easily dissipated underground). (It's the opposite of your fridge and your air conditioner, which pump the heat in the other direction; the back of your fridge and the outside of your conditioner end up blowing the extracted heat outside.) That compressing and evaporating takes energy itself (air conditioners and fridges aren't cheap to run), so it's not completely free. Places with underground steam (again, such as in Iceland) can use that steam more directly, without requiring the expensive heat pump stage.

(Feel free to correct anything I got wrong, but I think I got gist of things correct...)

Cap and trade

[Taxman415a]

What cap and trade systems are is a way to allow markets to most effectively allocate the costs of and pollution caps or reductions. If the government is going to mandate a pollution reduction, it would cost some firms so much they would go out of business. While that is ok to some people, it is not ok to most, and especially not to those whose jobs are at that company. But they may be able to buy pollution or carbon credits from another company that can more easily reduce their pollution. That way the overall desired reduction or cap (lack of increase) in pollution is achieved with the least cost. In other words, if no cap and trade system is implemented and no pollution reductions are required it's status quo, but if caps or reductions are desired a cap and trade system is the most efficient way to go.

The lack of understanding of cap and trade systems by people that claim to be environmentalists is really astounding to me. I'm not disparaging you because you are not one of those claiming to be in the know. They really are however one of the most brilliant solutions to pollution. It's not a cap and trade system that allows pollution, it's whatever targets are set for the caps or reductions that either allows people to continue polluting or forces them to reduce.

Re:Cap and trade

[Agripa]

As I see it, the big problem is that cap and trade is spectacularly susceptable to rent seeking and regulatory capture. A carbon tax levied on non-renewable energy to offset negative externalities is much easier to both administer and understand while providing incentives through economics.

Re:Cap and trade

[Anonymous Coward]

As I see it, the big problem is that cap and trade is spectacularly susceptable to rent seeking and regulatory capture. A carbon tax levied on non-renewable energy to offset negative externalities is much easier to both administer and understand while providing incentives through economics.

Yes, instead of giving people positive reinforcement for making environmentally sound choices that will have positive benefits even after the global warming pseudo-science is long forgotten, lets just raise taxes.

Re:Cap and trade

[Taxman415a]

Yes, instead of giving people positive reinforcement for making environmentally sound choices that will have positive benefits even after the global warming pseudo-science is long forgotten, lets just raise taxes.

Well a pollution tax is a good potential option as well. As a staunch fiscal conservative, I don't agree with many taxes, but pollution taxes can be used like a cap and trade system to bring externalities back into a market.

What can be done in theory is replace other taxes with a pollution tax. That way the non polluting behavior is taxed less and the polluting behavior is taxed more. Of course the cynical will note that a new tax will not really ever replace anything for long, it will just become additional as the other tax is raised again. I suppose that still levels the playing field a little.

Also the GP post's characterization of cap and trade as "spectacularly susceptable" to rent seeking is not only a mischaracterization of what the linked source said, but it's not really a reliable source to start with.

Re:ground-exchange? the price tag hurts...

[djtack]

So explain this, why am I to trust a company that clams 300% efficiency?

Strictly speaking, the vendor is describing the coefficient of performance. It's quite common for heat pumps to operate at 300-400%.

2nd your comment on the optimistic view of cost

[Latent Heat]

I second your remarks about the costs not being anywhere near "only 50 percent more than a conventional system." A colleague of mine lives on a small exurban farm, does hot water heat with LP gas, and supplements with a wood stove. His hot water furnace gave its death rattle and he had to put in a new system. His replacement hot water furnace as $8000 as in eight-thousand-freakin'-dollars. I put in a new hot-air furnace (condensing, variable-speed DC blower, top-of-line) and a new 13.5 SEER central air 15 years ago for about half that money. But he got bids on "geothermal" (i.e. ground-sourced heat pump) in the $30,000 range. Mind you he lives on enough land that it is not one of the these deals, "oh, we have to figure out to get the backhoe into your yard without trampling the neighbors flower garden." He has enough space to put some equipment in and trench away. Thirty-thousand-even-more-freakin'-dollars, what is that all about? You can get a septic mound put in for 10K as a more or less standard install. I am beginning to think this is tied into the housing bubble. A lot of those exurban home owners are retired doctors from the town with the teaching hospital, a lot of them are politically "progressive" about energy use and have money, and the 30K may be a question of sticking it too people for what the market can take. The 8K high-efficiency propane hot water furnace may be the same deal, and I suspect that prices of heating plants and central air are at an all-time high. My colleague is not in that category and had to take out a second loan on his house. I went to this evening energy-saving seminar from the local utility company a couple years back, where they lay the guilt trip on you for not spending on the latest energy saving appliances. One of the people drawn to this thing was this lady who lived out in the exurbs (yeah, yeah, if you believe the hype, these people living "in the country" in the far outskirts of cities are "part of the problem", but these are the folks who have enough land to dig the trenches for these systems). She had put in a ground-source heatpump, and it was nothing but trouble along with getting the contractor to give her some kind of satisfaction on getting the system working. I think at the time that system had broken down, and she was in October in a Northern state without heat, having waited all summer for a new compressor. She was there at this "energy seminar" to get some sort of feedback or help on how to get this wonder energy-saving system working. She also wasn't getting much satisfaction from the utility-company dudes. I took a look at the bills she brought and was able to tell her that this system was seriously underperforming, essentially performing at the level of electric resistance heat. She thought too that the compressor breakdown had to do that the system wasn't installed or sized correctly and was putting too much wear on the unit. The other thing to consider is that they got rid of that gosh-darn Rankine (steam or vapor cycle) in railroad locomotives long ago, they are getting rid of it in electric power plants, and the last holdout of the troublesome thing is in nuclear power plants and home AC/heatpumps. Given that you have to maintain a charge of fake-Freon, which tends to leak out of systems over time, and what they stick you for of repairs of such leaks, and then issues of the lifetime of a compressor compared to a combustion furnace without such moving parts, it is possible to spend as much on first costs and maintenance of such systems as you get back in fuel or electric cost. Talking about the utility-company guilt trip about going with the latest gadgets, the suits were pushing on-demand gas water heaters. Not soon after that, flames started shooting out of my gas water heater, and I had the utility guy over (one of the service techs, and you pay for the service call), not one of the suits, who condemned my water heater. I made some calls to plumbing companies without finding anyone who would install an on-demand unit. I asked the u

Re:2nd your comment on the optimistic view of cost

[MrKaos]

I would love to read your post but, without white space, gak!!! please repost!!

creek?

[zogger]

You have a creek for a cold water source? If it is close by, just the regular pvc pipe buried would be good enough, but any distance maybe you might want to think about insulating it so it doesn't lose coldness/gain ground warmth. Maybe a pipe inside another pipe with that split pipe insulation stuff on the inner pipe.

Re:creek?

[JWSmythe]

    She has a small lake in the back. It should be cool enough at the bottom. I'm going to have to test temperatures before I start. I'm pretty sure it's spring fed. That's about as cold as it gets around here, since the water comes from deep underground. That's about as close to ground temperature as we can get. :)

Well city won't let me dig a well

[Anonymous Coward]

I'll get to the point but first a little background.

It is an odd reversal here, but because sewer rates are so high here and city water metering was the way to measure sewer use. People in the suburbs started drilling wells in my area because it has an easy to get at artesian water table. Without the the use of city water there was no way to tax the sewer use. Got the idea and how it is going to apply?

So the city in it's infinite wisdom decide that wells were 'verboten' no matter what over the whole area. There is no way that you can get a permit.

Now you may think that explaining what you want to do to heat your home would get you a variance. Not simply because the city won't budge, but even more ludicrous is they think you will cheat and not put the water back in the ground as that costs more, but will dump the water into the sewer and increasing the water to the plant for free on your side. Thus making you a thief before found to be one. So easier and cheaper for them is to ban wells period no matter how well intentioned you are to green the planet.

It's to bad I wrote this late as it is not likely to be moderated high enough to get noticed and other point out a similar problem in their area that stops this type of system dead before it lives.

Re:Well city won't let me dig a well

[Cormacus]

Posting to cancel mod - I thought this was "interesting," but I somehow ended up with "Redundant."

New?

[Anonymous Coward]

What's so new about this. My ex-boss had his installed almost 20 years ago in MA. My house is almost 5 years old and I installed mine when we built. My heating bill is close to 50.00 per month in the Northeast - this is not new technology and I expected better from Slashdot.

Radon?

[mkcmkc]

Sounds really cool (heh heh), but I hope you tested for radon gas...

This Is What My House Will Use

[Ferretman]

I'm getting ready to build a house this summer, and it's going to use a ground-source geothermal heat pump system for both heating and cooling. In my case it was a simple matter of cost--a propane-based forced air system would be VERY expensive. A geothermal system requires no propane and is very simple once installed...plus the fact that it's "green" is a bonus.

Steve

Re:This Is What My House Will Use

[wpiman]

The compressor runs off of the electrical grid: which uses fossil fuels. There is nothing green about it.

Re:This Is What My House Will Use

[OneSmartFellow]

There is nothing green about it.

Of course there is, the energy to pump the heat transfer agent (water with some chemicals in it) is a fraction of that required to heat from normal methods. Take for example a house heated via radiators. In that type of systen, you have an (usually) electric pump to move the heat transfer agent (water with a few chemicals) and a (usually) gas fired boiler unit to heat the water in the first place. The electricity usage is a small portion of the total energy usage in such a system.

This same system can also be used to cool the house on hot summer days as well.

Now, I'm no expert in 'greeneology', but this system is more 'green' than conventional systems.

Re:This Is What My House Will Use

[400_guru]

Absolutely correct, it is MUCH greener. Standard HVAC wisdom is that it is always cheaper to MOVE heat than to MAKE heat. That is what the COP (Co-efficient of performance) number is indicating. A Heat Pump with a COP of 1.0 is exactly as efficient as that electric floor heater you buy at the local hardware. 1 KWH in yields 3413 BTU of heat. Now use that electricity to run a GEO unit with an overall COP of say 4 (Very doable and includes well or other pumping costs.) and you get 13,652 BTU for the same fossil fuel input.

AND most of these units can take the heat pulled from the house in the summer and put it into a hot water tank for DHW use. Really and truly $FREE hot water.

Re:ground-exchange? the price tag hurts...

[chrispitude]

I don't have the system up and running long enough yet to have good kWh measurements. I bought a Conserv ELF 3234 panel meter. It's a great value for the money, but the manual is absolutely terrible. The company is Indian and I suspect the manual author is not a native English speaker.

While I don't have monthly kWh values yet, I can share kW readings. With resistance heat running (I can force this with the thermostat's emergency heat setting, or by forcing a stage 2 heat call at low outdoor temperatures), the entire system consumes about 9kW. Depending on the outdoor temperature and the call from the thermostat, the system runs in four different modes:

Code:

M1 - Single cylinder primary compressor
M2 - Two cylinders primary compressor
M3 - Primary and booster compressors
M4 - Primary and booster compressors with 1st stage auxiliary heat

Heating Call at Thermostat

exterior temperature stage 1 stage 2
BIN A: ODT<-30 W1 W1
BIN B: -30<ODT<15 M3 M4
BIN C: 15<ODT<25 M2 M3
BIN D: 25<ODT<34 M2 M2+W1
BIN E: 34<ODT<41 M2 M2
BIN F: 41<ODT<62 M1 M2
BIN G: 62<ODT M1 M1

Sorry about the formatting, I can't get PRE tags to work here.

Normally the thermostat calls for stage 1 heating or cooling. If it senses the set point cannot be held with stage 1, it will step up to a stage 2 call. The Hallowell thermostat (just an off-the-shelf White Rodgers 'stat) has a feature which proactively ramps up the set point ahead of time. Since I have the temperature set lower at night to make sleeping comfortable, this ensures the morning ramp-up to 66F stays stays in a stage 1 call even when exterior temperatures are cold.

Using the ELF 3234, the power consumptions of the modes are about as follows:

M1 - 1350 watts
M2 - 1650 watts
M3 - 2900 watts
M4 - 8900 watts

- Chris

Self-powering?

[Zaphod-AVA]

I have always thought that combining one of these systems with a passive solar heat storage block and a Stirling engine to help power the pump would be fantastic.

Little Known?

[Anonymous Coward]

This technology is fairly well known, and in wide use, at least geothermal. My uncle in Manitoba (Canada) has been using geothermal heat for about 10 years. Fuel oil was getting quite expensive so about 30 one hundred and fifty foot deep wells later and one heat exchanger, and even when its freezing cold (the US doesn't know cold like Manitoba), the house stays a constant 25 degrees C (about 77 fahrenheit). All he needs is electricity to run the pump in the heat pump (and wind and solar will prevent bad storms/no power from affecting him at all). He didn't do it to be green, he did it to save money. The green part is a mere side-effect --sorry all you tree huggers out there).

Re:"little known" ??? Too bad that Citibank

[davidsyes]

Didn't 'bank' on this...

Geothermal heat pumps

[Anonymous Coward]

Much depends upon the stable ground temperature where you are. That temperature is within one degree of the average full-year air temperature. Thus, if you live in Texas, the ground temperature is already within the comfort zone and a ground source heat pump is extremely practical.
If you have enough space, a ground loop is often much cheaper than drilling wells. The exchange pipe is generally buried about five to eight feet deep--you can rent a trencher for the job.
Other factors include the thermal transfer characteristics of the soil in your location. A good HVAC engineer can figure out how much of a loop is required.
If you have a lake or a pond, that is even better.

Like $.35 off coupon for a Mortgage...

[weston]

Seriously, I find it sad that we have an article about geothermal heating and cooling that is used by the private residence of the leader of the free world and it's not mentioned.

Maybe the omission wasn't part of a sinister agenda to deprive W of his due, but not unlike recent Republican distancing from the sitting President. It wouldn't be the first time someone assumed that affiliation with the current leader of the free world might not be the best promotional angle.

Has Bush Derangement Syndrome gotten so bad that saying anything good about Bush is taboo?

It's neat if there's efficient and/or off-the-grid tech in his personal residence, but measuring the positive impact of that choice against the wake of his policies is sortof like crowing about a $.35 coupon for a home mortgage.

"Aren't worth the $$"?

[Doc Ruby]

Where electricity is uber expensive, and there's lots of heating and cooling (like here in the Northeast) that can use ground heat pumps instead of electricity, is exactly where heat pumps are worth the most money. Because they replace expensive energy.

And if Greenpeace is making your electricity expensive by owning either an electric utility or an OPEC country, you should get the kind of Greenpeace that everyone else has, which doesn't.

Yes and no

[yabos]

I completely agree that this tech. is NOT a "little known" thing. This has been around for over 30 years. I do disagree that this is unsuitable for northern areas because geothermal heat pumps are used all throughout northern Canada where it gets to -40C(-40F) in Alberta and Saskatchewan for example.

In almost every instance a heat pump will save you money on the month to month heating and cooling(it will reverse directions and air condition in the summer). The initial expense is usually around $20,000 CAD to $30,000 CAD which if you are getting a mortgage is easier to absorb most of the time than after you've already built the house.

little known technology?

[Anonymous Coward]

little known to who? pfy computer geeks? stick to trek trivia slashdot! Just because you think that knowing how to play tetris while downloading pirated mp3s makes you l33t. That doesn't make this crowd the technical elite.

Pay me now, pay me later....

[400_guru]

We have used Geothermal since 1992 and it is wonderful. We use our home's well (only 80 ft deep) which stays +-1 from 10C for the source. The unit not only is very quiet it also produces most DHW for the house whenever it's in use. Our electric coop gives a $0.03/KWH discount for Geo users making it even more attractive. Theoretically the unit can handle temps down to about -12C before resistance backup kicks in but we have them turned off and have never noticed even this past week when temps hit -23C in Michigan. In the winter the water goes down a dry well while in the summer the water warmed by the heat-pump is re-routed and used for irrigation. In addition to the Geo unit we installed a Heat Pump water heater in July to provide hot water when the Geo heat-pump isn't running (or running enough) This is a unit that provides roughly $3 worth of hot water for $1 of electricity when compared to a standard electric water heater. (No discount from the coop on that unfortunately) Payback is tracking about 2 years right now on this unit. Our house is 100% electric - no gas in our area.

Yes it is

[yabos]

Modern ground source heat pumps can get 3KW of energy from the ground for every 1KW of electricity used. This is much more green than every other heating source except for hot spring geothermal and passive solar.

Screwing with the Earth

[jameskojiro]

We alter the air temp and now we want to mess with the ground temps too. Great, why don't we just blow up the planet while we are at it.

Who pays for this commercial?

[Couzin2000]

I hate to say it, but Geothermal heating systems, even in residential areas, is alraedy available, and has been for such a long time - more than 20 years ago my uncle installed one and it's been working great ever since. So who decided to post an article HERE, of all places, where most geeks are already aware of this technology and don't need a summary of what it is, like it's 1983? I wonder how far the bias curve goes... are we getting info here in Slashdot on a "need to know" basis? Is there someone paying so that these articles appear here? I thought this was a publicly-driven website, not commercially-driven. Where'd this come from? And in case you need info about geothermal heating, check out http://www.geo-exchange.com/. That's a site with in-depth info, standards of the industry, and all that. Don't just give me an article of microwave-reheated crap.

More tech details here

[Anonymous Coward]

http://www.ventilone.com/indexEN.php?section=geointro

Re:ground-exchange? the price tag hurts...

[DuckDodgers]

Most of the added cost of ground source is getting the wells drilled and the piping from the wells into your home. In 20 years, you may need to replace your compressor, but barring some very unusual problems you well should be fine for many more decades.

Plus, the ground source system compressor is indoors, which improves the system longevity versus an outdoor traditional air-source heat pump.

Funny enough, we're in the middle of having a ground source heat pump installed right now. We opted for ground source over air because our house is old, some of the walls are stone, and it's in an L shape. So we have high surface area for relatively modest interior space (2100 square feet for a family of five), and some of the house is effectively impossible to insulate well. My wife and I figured that no matter what we do, we're going to lose a lot of heat. A hypothetical 25% cost savings difference between an air source heat pump and a ground source heat pump will pay for itself with our home far more quickly than most better shaped, better insulated properties.

We live between Philadelphia and Reading. Funny that you're near Tannersville - my best friend grew up outside Snydersville, PA. His parents' house is probably in your back yard.