The Resilience Hub & Portland Maine Permaculture Message Board › experience with geothermal?

experience with geothermal?

Mary
marygee
South Berwick, ME
Post #: 7
Ok, so now we have a possible lead on a house being built that will have geothermal heat. Does anyone know of a useful website/book/other source that could provide some useful information? I'm thrilled with the idea, but my husband has some questions I can't answer. I think it's a HUGE reason to pursue this house over others....he's not sure.

Any insight would be great!
Lisa F.
lisa.f.organizer
Group Organizer
Portland, ME
Post #: 427
Mary, I told Dave you posted this and he said you should give him a call on his cell phone. He has a ton of questions that he would recommend you ask regarding the house.
A former member
Post #: 141
Not sure if this is at all helpful, but today we visited a home that is "bermed" (not sure if that is the correct term) on the north and they said they can leave for the winter and not worry about freezing as the temperature never drops below 50.
Ted M.
TedMarkow
Brunswick, ME
Post #: 62
Mary,

Geothermal is essentially a ground-source heat pump - the best kind for a climate such as Maine. I don't know much about it, but just read a great article on it in Mother Earth News (April/May 2005). It explains it pretty well and you may get some sense of what it is and whether it's right for you. (Note: The first part of the article covers air-source heat pumps, which are not the same as geothermal. Keep reading for the geothermal stuff).
Lisa F.
lisa.f.organizer
Group Organizer
Portland, ME
Post #: 429
There are a few companies that are testing out air-source heat pumps that are appropriate for our climate and they look very promising. Essentially they extract heat energy (even from cold air) and use those extracted BTUs to heat the home or water. It is a little bit counter-intuitive, but if you can pull a few degrees from a cubic foot of cold air (say, taking that cubic foot from 30F down to 28F) you're gaining a couple of degrees per unit of air. Extract enough of those degrees and use them to heat water (or whatever...), and you've got energy. These are also being used in reverse to air condition in some parts of the country. Air-source and ground-source heat pumps both require energy to function, but it is a worthwhile net gain after considering the energy they produce.

Expect to see a workshop on residential geothermal (ground source heat pump) later this year.

These things really start to make sense at the neighborhood (or subdivision) level where the infrastructure for it can be installed once and service a number of homes nearby. A *very* local utility!
zengeos
zengeos
Gorham, ME
Post #: 203
Indeed Lisa....many people have leech fields which are actually perf pipe or other leeching materials for their septic systems...it really makes sense to dig just a foot or so deeper and place close loop heat pump systems in. In fact, that might make a heat pump even more efficient. Of course.,..it only makes sense for new construction I suspect. Since trenches would already be planned for leeching I should think that digging a little deeper for the heatpump loop would be less costly than separate systems and locations.

for retro I think an open system is probably most effective, cost wise, but that wastes a lot of water....5-10 gallons of water each MINUTE the pump works...and up here in Maine that's a LOT of minutes....
David S.
stereoview
Washington, ME
Post #: 185
I have given this quite a bit of thought and researched it some. Apparently, you need what boils down to a reverse air conditioner to have heat. So you still need a serious amount of electricity.

It makes more sense to me as an air conditioner in the summer. Just suck cool air from underground.

I tested the temperature of my well water this winter which is 145 feet deep and it was 46 degrees. Brrrr

I've been thinking about whether you could have a heat exchanger in a really hot compost pile or septic tank. There is no snow over my septic tank all winter long. Of course the constant exchanging would lower the temp of the tank which may be bad. I may try growing some plants rated for zone 6 over my septic tank.
Lisa F.
lisa.f.organizer
Group Organizer
Portland, ME
Post #: 433
I always forget to add the fact (because I assume you'll all agree:) that none of these technologies matter if we don't REDUCE the demand side of the equation. A bunch of supply-side solutions (i.e. "technology will fix everything") will help to some degree, but the biggest area for urgent improvement is in reducing demand (better insulation, smaller homes, shorter/fewer hot showers? etc....)
zengeos
zengeos
Gorham, ME
Post #: 204
Ouch Lisa!

You are right though...which is a reason why I am not averse to having house mates...it's not like I don't have the room.....


Heck...I have enough land that I can share garden plots with others if they so desire. Of course, to share farm plots I'd want water source other than from my well...perhaps a 1000 or 1500 gallon water tank supplied from roof runoff or something.

Perhaps a combination of solar panels and heat pump might be beneficial. Of course, the solar panels only work in daylight....
Ted M.
TedMarkow
Brunswick, ME
Post #: 64
I always forget to add the fact (because I assume you'll all agree:) that none of these technologies matter if we don't REDUCE the demand side of the equation. A bunch of supply-side solutions (i.e. "technology will fix everything") will help to some degree, but the biggest area for urgent improvement is in reducing demand (better insulation, smaller homes, shorter/fewer hot showers? etc....)

What? Are you serious?! Me, change my habits?!! My God-given right to this lifestyle?!!! Sounds positively heretical!!! Actually, some heresy is probably what's called for. Count me in! biggrin
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