geothermal....has the time come?

A meeting place for regulars to discuss the lighter side of old-houses.

Moderators: oldhouse, TinaB, Don M, Schag

Ted
Posts: 4
Joined: Thu May 04, 2006 5:59 pm

geothermal....has the time come?

Post by Ted »

After doing search for 'geothermal', I see that it was discussed last about 2 to 3 years ago........with gasoline back up almost to $3.00 again with no relief in sight, natural gas way inflated these past couple winters, and so on........does ANYbody out there have good info (hopefully first-hand experience) to share about this great heating & cooling technology? The argument has been all along that the initial cost makes it simply impractical compared to all the fossil-fuel stuff. Now, I wonder. USAToday had great article a few weeks ago about how 'alternative' energy sources are finally trickling down to the masses, especially with Fed incentives in the new Energy Bill, but not one little mention about geothermal! Personally, I'm not too thrilled at the prospect of covering my mid-1800s farmhouse roof with solar panels, if there's an equal or better energy option. The one unknown that does worry me is this: does it really use a bunch of electricity to circulate the water/coolant? I may very well also install a windmill or PV solar panels so I can get 'free' electricity & even sell some back to the power company --- I have 5+ rural acres so plenty of room to install such stuff --- but would really like to hear the straight skinny on this aspect of GT from people who really own the stuff....as well as any other considerations.

HB
Posts: 1645
Joined: Wed Dec 10, 2003 12:24 pm
Location: Reading - PA

Post by HB »

As I understand it Geothermal brings groundwater up and circulates it through the house or through a heat exchange unit. Since the water is always 55 degrees you only have to provide additional heating from that point to 65-70 degrees instead of from the outdoor temperature.

The downside is that tyou have to pump the water out of the ground. This means that you pay for the electric for a pump to circulate the water whenever the system is running (almost constantly from what I understand).

You'll also need a dedicated well for this puropose and you need to hope that withdrawing that much water fom the ground won't run your drinking water well dry, and then on top of that in a drought situation (they happen in winter too) you'll need to turn off the well so that you don't deplete yours and your neighbor's drinking wells. You also need to have a place for the water to go. Some systems might use a second well to inject the water nack into the ground, but that takes some power too.

I think that the theory is ok, but the practice isn't quite there yet. You would be better off building a large portion of a new home below grade with southward facing windows (in this hemisphere) to take advantage of natural heating and cooling.

All things considered - with an existing house, I'd be more inclined to look into wind power to provide electricity for yourself, and then use some of that to heat and cool the house.

Wind turbines are getting more efficient and cheaper as time goes by.

Good Luck.

HB

oldhouse
Site Admin
Posts: 263
Joined: Sat Dec 06, 2003 3:29 pm
Location: South Gardiner, Maine
Contact:

Post by oldhouse »

Deb and I were at a party over the weekend at a rural bed-and-breakfast / conference center here in Maine. Out in the field, on the top of a slight hill, the owners have a recent installed windmill. It got me to thinking ... as here at the Holmes household, in our back yard, we've got wind. Our home is about a quarter-mile off a major river, and the wind comes up the river, or down it, and then across a large field in back of our house.

So, while we're talking: Anybody out there with a windmill? And, if so, tell me a story about it ... how much it cost, how much electricity it generates, how much of a pain it is to maintain, etc.
The Old House Web

al_roethlisberger
Posts: 926
Joined: Sun Feb 26, 2006 6:33 pm
Location: Sanford, NC
Contact:

Post by al_roethlisberger »

And here's a slightly different tack I was thinking about just today on a smaller scale.... for those of us lucky to have "cold ole basements"(or warmish in the Winter).... why do we let that big lump of colder air sit down there going to waste?

I thought that it might be an interesting idea to simply use an airhandler(blower) with a thermostat to blow colder air from the basement upstairs and let it circulate. This isn't too different than old attic fans, and could be used to augment an A/C system and reduce its load.

Has anyone done something like this?

Al
Lewis D. Isenhour House
http://www.isenhourhouse.com

lrkrgrrl
Posts: 4733
Joined: Tue Jun 28, 2005 9:50 am
Location: Northeast

Post by lrkrgrrl »

Here's a link to the Geothermal Consortium:

http://www.geoexchange.org/residential/GB029.htm

This is an industry group, and hey, horses mouth and all that....

There are both water and ground source systems. If you have the space, ground source eliminates the water supply issues mentioned above.

My understanding is the electric demand shouldn't be too crazy, since most traditional heat sources also have electric demands for fans and or pumps (hot water systems).

I commend you for exploring alternative technology. Do you have any companies locally that do this sort of thing? Cost is an issue if you have to import a contractor.

Don M
Posts: 6965
Joined: Mon Dec 08, 2003 11:35 am
Location: Boiling Springs, PA

Post by Don M »

The housing department at Carlisle Barracks, PA (Army War College) installed Geothermal wells for heating & cooling some of the officer housing a couple of years ago. This Old House installed it in their Nantucket project house a number of years ago and it's a viable system, just expensive initially. I think the Nantucket system required two drilled wells that created a circulation, water up through the house system & back into the second well?! Don

jeepnstein
Posts: 2196
Joined: Tue Aug 17, 2004 10:16 am
Location: Sciotoville, Ohio
Contact:

Post by jeepnstein »

I used to run around with a guy who did ground source systems in the early eighties. They were really fantastic if you had the space. His attraction to them was the fact he got to charge out the wazoo for installing them. He also was quite impressed with the energy savings and enviromental impact.

I always wanted to do one if I ever built a new house. It would go well with the net-metering solar power.

J.

Starr-Point
Posts: 430
Joined: Sun Jan 22, 2006 3:36 pm
Location: North East, Maryland
Contact:

Post by Starr-Point »

I have a customer in Chestertown, MD with geothermal. It is quite a large old town house - 4000 sq ft - and the system works very well. In this case it was dreadfully expensive - about $85,000 - which is only slightly above the norm in this area.

Whay? You need at least two wells, generally, often as many as six or seven. Most of the piping is satinless steel, and you need atleast a couple of pumps. Yes, it will pay for itself, but you're talking decades. If I had the cash, I'd do it in a heartbeat, though.

I know next to nothing about wind except that it takes more than a breeze to make the turbine go. And it's better than solar, but what isn't? Maybe that's a technology that will pay off someday.
RSS

jeepnstein
Posts: 2196
Joined: Tue Aug 17, 2004 10:16 am
Location: Sciotoville, Ohio
Contact:

Post by jeepnstein »

The systems I'm more familiar with were "closed loop". They had hundreds or thousands of feet of plastic pipe buried then filled with an anti-freeze solution. This pipe field was the source for a heat pump.

One system that I particularly liked had the closed ground loop providing heat to radiant heating system in a concrete slab. I've never seen anything like it since. I don't know if it was really all that efficient but it sure was impressive.

My main knock on heat pumps is they don't produce comfortable heating this far north and they generally require another heat source. I guess if the energy savings were sufficient I could learn to like them. I wouldn't mind having a closed loop geothermal heat pump for AC.

J.

Sacto Diane
Posts: 592
Joined: Fri Nov 05, 2004 1:04 pm
Location: Sacramento
Contact:

Post by Sacto Diane »

I think that Jeep touched on this a bit but from my understanding is that a geosource based system does not "bring up ground water" but leverages the geothermal consistencies of the ground mass. Basically the ground under a certain level stays at a given temp (58F?) and and heating and cooling system can leverage this to heat and cool a house.

In essence, for heating, pull heat from from the geo mass and vice versa for cooling. You leverage a closed loop system that circulates a heat exchanging coolant and you circulate the system depneding if you wnat heat extraction or heat removal.

I looked a geosourced based system for my HVAC system when I replaced it several years ago. It has a big up front capital cost but will return it's cost over the years based on reduced energy costs. With the higher fuel bills, you'll have a qucker ROI on the up front costs.

For me, I did not do it as I did not have the lot space to drill the needed well to insert the closed loop system. There are "open loop" systems that do leverage existing ground water but from my understanding this works only in certain cases. I did not go into detail when I researched so I could be missing some key elements. If I had the lot space I would have gone with the closed loop system as I think that it would have had a pay back over the years that I plan to stay in my house.

Diane

Post Reply