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Author Topic: Geothermal Greenhouse  (Read 441 times)

will2358

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Geothermal Greenhouse
« on: July 06, 2019, 12:17:25 AM »
Does anyone have or ever had a Geothermal greenhouse. I wish I lived on rural property so that I could build one. It did cost a lot to heat the greenhouse, when I had it.
https://www.youtube.com/watch?v=ZD_3_gsgsnk
https://www.youtube.com/watch?v=Ibaf_rkW_30
« Last Edit: July 06, 2019, 12:21:03 AM by will2358 »
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SoCal2warm

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Re: Geothermal Greenhouse
« Reply #1 on: July 06, 2019, 12:56:24 AM »
The pipes only need to go 12 feet down into the ground, although  18 to 23 feet is more optimal.
Probably also a good idea to design in a drainage pipe and pump into those pipes, to be able to remove any water that condenses from humidity down there.

It's not so much geothermal heat, more like the earth acting as a thermal battery between night and day. Get some hot greenhouse temperatures and you can pump a lot of heat energy down there during the day.

Here in the PNW, the coldest nights in the winter always come after clear sunny days.

SeaWalnut

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Re: Geothermal Greenhouse
« Reply #2 on: July 06, 2019, 01:49:12 AM »
Thats geothermal but the condensation in the ground should not happen in winter  because the air from the GH its colder than the underground pipes.In the summer if hot air goes through the cold pipes,then it will condensate.
I toght at this before for my greenhouse but il build a rocket stove that works on wood because its less work and i have a lot of branches to burn on my property.

SoCal2warm

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Re: Geothermal Greenhouse
« Reply #3 on: July 06, 2019, 02:10:11 AM »
Thats geothermal but the condensation in the ground should not happen in winter  because the air from the GH its colder than the underground pipes.
Not during the daytime, with full sun.

Even in winter, under clear skies it could get to be over 100 in that greenhouse if things were not vented out somehow.

In the case of geothermal greenhouses, that heat is vented down into the cool ground. At night, that ground, while still kind of cold, is still warmer than what it would otherwise be inside the greenhouse. Things don't need to be kept very warm at night for plants to grow.

SeaWalnut

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Re: Geothermal Greenhouse
« Reply #4 on: July 06, 2019, 03:08:08 AM »
Thats geothermal but the condensation in the ground should not happen in winter  because the air from the GH its colder than the underground pipes.
Not during the daytime, with full sun.

Even in winter, under clear skies it could get to be over 100 in that greenhouse if things were not vented out somehow.

In the case of geothermal greenhouses, that heat is vented down into the cool ground. At night, that ground, while still kind of cold, is still warmer than what it would otherwise be inside the greenhouse. Things don't need to be kept very warm at night for plants to grow.
Geothermal means a stable temperature all time,day and night ,summer and winter.At certain depth,the soil has same temperature in winter and in the summer and day/ night differences doesnt matter .The depth of that layer varies by the topology and climate of the terrain ( in Siberia and Canada there is permafrost-a soil that stays frozen all the time even in summer but underneath that it gets warmer and stavle just like the permafrost). I was thinking to run water through radiators inside the greenhouse conected to a heat exchanger mounted in my well .Since my well its 37 meters deep and made of one meter wide concrete tubes ,there is a lot of space for a big and efficient heat exchanger.

Ilya11

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Re: Geothermal Greenhouse
« Reply #5 on: July 06, 2019, 03:26:02 AM »
I was thinking to run water through radiators inside the greenhouse conected to a heat exchanger mounted in my well .Since my well its 37 meters deep and made of one meter wide concrete tubes ,there is a lot of space for a big and efficient heat exchanger.

Probably will cost more to constantly pump a water up this height than just to heat with electricity.
Best regards,
                       Ilya

SeaWalnut

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Re: Geothermal Greenhouse
« Reply #6 on: July 06, 2019, 04:04:58 AM »
I was thinking to run water through radiators inside the greenhouse conected to a heat exchanger mounted in my well .Since my well its 37 meters deep and made of one meter wide concrete tubes ,there is a lot of space for a big and efficient heat exchanger.

Probably will cost more to constantly pump a water up this height than just to heat with electricity.
Id wouldnt cost more than normal because the pump would be on the surface pushing water from one end and the pump  doesnt have to be high pressure.Altough the water goes deep ,the pipes should be full and the rest its done by gravity.
The heat exchanger its a spiral made from plastic pipe and a closed loop inside the well.

SoCal2warm

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Re: Geothermal Greenhouse
« Reply #7 on: July 06, 2019, 04:59:53 AM »
In terms of electrical power, it takes far more energy to heat than to circulate air or water around.

In fact, I have speculated that in cooler climates, like say Iceland or Alaska, it might be more energy efficient just to use artificial lighting and completely enclose the structure in thermal insulation (at least during the winter). It takes more energy to heat than to provide the necessary light for growing.

But of course there's also the trade-off between energy efficiency and cost. In many cases it might just be a lot cheaper to have a ceramic heater automatically turn on, as long as it only needs to be on during the coldest nights.

Samodelkin

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Re: Geothermal Greenhouse
« Reply #8 on: July 06, 2019, 08:04:33 AM »
This is effectively done in the valley of hot springs ;D
Geothermal energy of the soil is not enough to heat the greenhouse. The energy consumed to move the coolant is not much higher than the heat received. Construction costs will never pay off.
Double glazing greenhouse more profitable investment

SeaWalnut

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Re: Geothermal Greenhouse
« Reply #9 on: July 06, 2019, 11:02:07 AM »
In terms of electrical power, it takes far more energy to heat than to circulate air or water around.

In fact, I have speculated that in cooler climates, like say Iceland or Alaska, it might be more energy efficient just to use artificial lighting and completely enclose the structure in thermal insulation (at least during the winter). It takes more energy to heat than to provide the necessary light for growing.

But of course there's also the trade-off between energy efficiency and cost. In many cases it might just be a lot cheaper to have a ceramic heater automatically turn on, as long as it only needs to be on during the coldest nights.
To heat with electric power you can use a heat pump ( also known as an air conditioner used for heating ) wich is up to 400% percent efficient.That means with 1 kw of electric power you get 4 kw of heat.with a ceramic heater for 1 kw of electric power you get a bit less than 1 kw of heat.


will2358

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Re: Geothermal Greenhouse
« Reply #10 on: July 06, 2019, 01:19:10 PM »
The earthship homes are warmed and cooled using geothermal heat. This greenhouse in the Colorada Rocky mountain uses a climate battery which I believe is geothermal heat.
https://www.youtube.com/watch?v=iKMi4Vlt_Ys
Here is a video on the poorman geothermal greenhouse.
https://www.youtube.com/watch?v=Ibaf_rkW_30
Subzero geothermal
https://www.youtube.com/watch?v=xo9KxzaU6Kk
Information on climate batteries.
http://www.ecosystems-design.com/climate-batteries.html
« Last Edit: July 06, 2019, 01:34:41 PM by will2358 »
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SoCal2warm

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Re: Geothermal Greenhouse
« Reply #11 on: July 06, 2019, 03:15:22 PM »
To heat with electric power you can use a heat pump ( also known as an air conditioner used for heating ) wich is up to 400% percent efficient.That means with 1 kw of electric power you get 4 kw of heat.with a ceramic heater for 1 kw of electric power you get a bit less than 1 kw of heat.
Yes, of course. I was considering mentioning that. But a heat pump has a much higher initial cost.

Actually, heat pumps combined with geothermal work really well together. It's easier to pump heat out of the ground that is 40 degrees than to pump heat out of air that is 10 degrees, let's say. This has been used to heat some homes, and do so very efficiently.

What a lot of people may not realize is just because something is cold doesn't mean it doesn't contain a lot of useful heat that could be used to warm things using a heat pump.


However, if the heat pump needs to be operating the entire night, every night during the Winter, in colder places (and especially northerly climates with shorter day lengths), I still suspect covering everything with thick insulation and using artificial grow lighting during the winter might be more energy efficient, even than a heat pump.

It depends on the specific situation and exact climate conditions. Initial price is also a big factor to consider too, since there might be a theoretically most energy efficient way to do things, but it might involve switching between 3 different strategies at different parts of the year. Obviously you would not really be getting your money's worth in that case. It doesn't make sense to buy a heat pump if it's only going to be used 1 month out of the year, for example. That money might have been better spent on going geothermal. So a lot of trade-offs.


Some greenhouses attempt to put the thermal mass inside the greenhouse, but it can be difficult or impractical to do that since a very large volume would be required. (I've looked into it and done some calculations)
Phase change eutectic salts are another possibility, but is generally impractically expensive considering the amount you would need. (I think that would only make sense if you were a large well-funded museum institution)

One last idea I thought of, if for some reason it was too difficult to dig into the ground, is have a smaller separate part of the greenhouse with a very large tank of water that was well insulated. Water would be circulated around in pipes. During the middle of the day, when the greenhouse is at its hottest, the water would be circulated to cool the greenhouse and absorb heat back into the insulated tank. Then during the middle of the night and early morning, the water would be circulated again to release the heat stored in the tank. This strategy would prevent the water in the tank from immediately releasing all its heat early in the night, and would also allow the greenhouse to heat up faster in the morning, without the cooler water keeping the temperature down. This could possibly help solve the problem of the greenhouse not having enough thermal energy to adequately heat the water for the night.

will2358

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Re: Geothermal Greenhouse
« Reply #12 on: July 14, 2019, 05:39:04 PM »
My name is Cindy

SeaWalnut

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Re: Geothermal Greenhouse
« Reply #13 on: July 14, 2019, 06:10:19 PM »
Greenhouse at 7200 ft
https://www.youtube.com/watch?v=6KCOY-LVXmk
Great stuff.I wonder if he is registered here too.

mikkel

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Re: Geothermal Greenhouse
« Reply #14 on: July 16, 2019, 12:08:53 PM »
"Citrus In The Snow" might be similar. At least you find a little more information about the design on the internet.

 

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