Okay the engineer in me is trying to come up with a solution for overwintering citrus in the cold parts of the country (which now includes San Diego). I've always been fascinated with the concept of geothermal heating and cooling where a series of piping is run deep enough below ground where it stays a constant 55 degrees F (if my memory serves me correctly). A liquid is then pumped through the piping and back to a heat exchanger that heats (or cools) the ambient temperature. In lieu of the big and expensive heaters that everyone has to use to keep their greenhouses warm in the winter, is anyone aware of any greenhouses heated geothermally? I know the initial cost is pretty high to install something like that, but when I hear some of the heating bills people are paying, I've got to wonder if it would work. I would imagine that there wouldn't be as much insulation in the green house as inside of a home, but I've seen those water bags for greenhouses that help protect against frost also.

Any thoughts?

All Patents Pending

Phillip

Dauben,

Are you that cold there in San Diego?

Our average soil temperature, which can be found at 5 ft and below, is at 67.19086022 deg F, based on 30 year soil temperature data.

55 deg F would be too cold, the citrus roots would be just slightly better than barely growing. Shoot for 60 deg F, perhaps your deep soil temp is better than that.

I have been thinking on this concept for a long while, especially for green houses. It provides heating in winter and air conditioning during the summer. It simply is too much cost if you already built your house. Another reason is for wine storage. Wine doesn't really need to be stored at low temperature, just that it should be stored at constant temperature, to prevent expanding and contracting thus pumping air in and out thus ruining it by the oxidation through time as temperature fluctuates. A constant underground temperature would be ideal.

Surely you can use it for your own "geothermal" heating. But what is going to happen is that your soil temp will now fluctuate as well, but serving as a big buffer.
Joe

Phillip
Your idea is a real possibility depending on where you live. My well water runs approximately 72 degrees at any time of the year and there are people who take advantage of this.
The idea is to drill two or there wells and loop the high side of your air conditioner in and out of these wells then back to the compressor. This works well and drops the discharge pressure of the system. This way you eliminate the condensing coil and fan.
Pump and Dump systems will use a small pump to flow through a heat exchanger with refrigerant flowing on the outside of the coils. This is also very efficient in that you don’t need a large pump to build pressures up to household needs. The water flows through the system and then dumped in a nearby ditch. There is a price to pay with regular cleaning of the heat exchanger.
Heat exchangers are expensive items but with the low pressures that you would need, I believe one could build his own relatively cheap.
The third way of cooling air conditioner discharge temps is to bury a series of coils looped below the soil in your yard. This works well most of the time but dirt is a good insulator and the cooling can sometimes come to a halt on very hot days.
The biggest draw back of all of this is that they require some type of pump that depend on electricity and you can not always count of a steady supply during the worst weather.
Karl

This is precisely the thought I have been pondering for the past few weeks.

I hope to eventually live 'off the grid' so to speak. I have been thinking of how I could heat my greenhouse (don't have one yet but it's on my list) without depending on the utility company. That eliminates the electric and gas companies. I didn't want to use wood stoves because of the problems associated with them. Do you think geothermal could be replaced by solar heating?

Using solar panels to heat my water and having the pipes set up in an efficient way to have heating on demand would be a perfect solution.

I know there are electrical systems available which uses batteries set up in rows to store the collected energy. I don't remember the technical terms for it, but I will be doing more research on it very soon.

I'm wondering if the pipes are buried on such a system, if the heat gain would be enough to offset the ambient temps of the space to be heated?

Does this give anyone any ideas? Do you think this is feasible?

Dauben, if you would like to contact a very large (30 acres under glass) commercial greenhouse, that utilizes a huge amount of geothermal heating, solar panels, and wind generation to heat their greenhouses, you can contact Mark Elzinga who is the president of Elzinga & Hoeksema Growers. They are located in Portage, MI. Mark was selected greenhouse grower of the year, by Greenhouse Grower magazine. See the link below which shows much of the operation, and all their sustainable energy controls. Be sure to place your mouse's arrow on the slide show pictures to bring up information on each slide. Happy New Year to you and your family. - Millet

http://www.greenhousegrower.com/specialreports/grower/?storyid=1524

Whoooeeee....check out those solar panels! That is one huge operation!!

Thanks for sharing that link Millet.

Phillip, congratulations on your property. Your a special member on our forum. Take care, and God bless. - Millet

That is wonderful news! Congratuglations Phillip! Barbara

Phillip:

Here's my gift to you, I initially promised this with a crude drawing or diagram, and it still is, but here it is for you to improve my design. The passive annualized heating and cooling of greenhouses based on design of geo-earth-tubes using simply the solid (not perforated) 3.5" corrugated PVC drainage pipes from Home Depot. The major expense would be the digging, which you can get by using a micro-excavator that you can buy (wise investment) or borrow from nearby friends (you have to befriend your neighbors, right?)

You can then use solar panels to drive the fans. You plant your trees in between the groups of geotubes. The aerators are another option to heat the plant roots via compressed air and supply the oxygen.


By joereal at 2008-12-30

One thing nice about my design as planned is that the plants will always have fresh supply of CO2 from the drawn air from the outside which are then either cooled or heated by the moistened soil layer. This works theoretically only in California. Moistened soil has several times heat capacity than air, so there is tremendous savings. The key is finding how many feet tubes you would need. Some literature that I've come across recommend a foot of pipe per square feet of greenhouse. Since the corrugated PVC drainage pipe is very cheap, I would use 2 ft pipe length per square ft greenhouse space.

After you bury the pipes as configured, then you can place a greenhouse over it. Something in the range of $2,600 that is 24 feet wide by 96 ft long, 3.5 ft sidewalls and 9 ft tall. I plan to add water catchment area to serve as thermal buffer on the side walls of the greenhouse by building half-submerged cheapo ferrocement style water wall tanks. This way, we are not only saving rainfall water which is the best to use, we are also literally averaging the greenhouse temperature, thereby tremendous reduction in the heating and cooling needs.


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330286461020&ssPageName=MERC_VIC_RSCKCK_Pr12_PcY_BIN_Stores_IT&refitem=330263995964&itemcount=12&refwidgetloc=closed_view_item&usedrule1=StoreCatToStoreCat&usedrule2=CrossSell_LogicX&refwidgettype=cross_promot_widget&_trksid=p284.m183&_trkparms=algo%3DCRX%26its%3DS%252BI%252BSS%26itu%3DISS%252BUCI%252BSI%26otn%3D12

Interesting link. the cold frame in that link is a Conleys greenhouse. Personally I'd check with them and compare the cost because that seems like a sweet deal for 96 foot long. In fact that cold Frame is what I have here that I've converted from a cold frame to a greenhouse with the polycarbonate siding, but there's allot of things that don't come with the price that's suggested there.
As with anything , anywhere, double check.

http://www.conleys.com/cold_frame.htm

Thanks all! I'm excited about the move. I spent an hour last night shooting the breeze with my new neighbors. Our new house just seems like a perfect fit. Close to work, 100 citrus trees, great neighbors, elbow room between homes, etc. I don't recall if I mentioned it here, but I thought I was buying 4.5 acres and it turned out the listing was wrong. I'm actually getting another 0.86 acres that I didn't know about that has even more citrus trees on it. Most are grapfruit, but due to the lack of water and maintenance a lot of them have reverted back to the rootstock. That will be my first question to the group when I get some pictures taken. The rootstock isn't grapfruit or lemon like I thought it would be. The leaves have 3 petals like a trifoliate, but much larger than trifoliate. My thought was that it might be a citrange although I've never seen one.

Anyway, I'm drifiting off subject.

Joe, does your gift include professional installation?

Thanks,

Phillip