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deep roots in green house = geothermal

 
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In theory, given deep enough roots, plants can pump as much heat as most passive systems can, up and down keeping the green house productive in all seasons.. Anyone know anyone with experience with this? I'm sure, in colder climates ever green trees with very deep roots, acting as a back wall, would not only absorb much more sun than many other types of foliage, but it'd do it very consistently all year.. Given deep enough roots and a slow water flow through the soil, summer heat and fall heat could be stored deep for winter, then as that heat is brought up over the winter, the cold is built up for the summer.. the average surface temperature would give a late fall grow and early spring growing.. What plants are best?
 
pollinator
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You weave an interesting hypothesis, but honestly I don't see how it could be viable.

There are a lot of big "ifs" and "gotchas." I can't imagine a greenhouse that would be big enough to accommodate trees that are deep enough. Even if the trees could somehow pump up enough heat to make a difference, they would absolutely rely on sunlight and ambient heat to do it (transpiration). If you had a multi-day winter storm, it would shut down the system.

The "gotcha," as I see it, is that most trees naturally follow a seasonal rhythm, which includes a period of dormancy during which transpiration slows or stops. This is not only from temperature, but a response to shortening hours of sunlight and the accompanying change in light wavelengths. So, the hypothetical heat pump would stop working when you needed heat the most.

My 2 cents.

 
Josh Golden
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Yeah definitely stuff to work on. Yeah most of the energy would come from the sun each day, but given a cold climat adapted evergreen, I think it'd pump whenever  it could..  And condensation of the transporation gives you back a good chunk of that heat.. When it can.. Another catch... But as long the ever greens have other uses, like say needles for fule for a rocket stove fire starter/add..  And say nutrient collection, hydrological  lifting, condensation water cycle, geothermal, they make nearly best living solar absorbing back drop, mulch, beneficial insects ect... Seems like it'd be worth a try.. Maybe it'd only be really worth it on the small scale if you were growing a very compact crop like cannabis... But in really big green houses, or earth ships.... Also some are shaped really well, narrow.. But I dont know anything about their root depths..
 
Douglas Alpenstock
pollinator
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I'm not sure which evergreens you had in mind. Spruce and pine, for example, are very shallow rooted.
 
Josh Golden
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yeah Iv never looked. There's got to be some evergreen plants with deep roots, Joshua trees with many 100s of feet deep roots, are the only one that comes to mind, but that probably likes it warm and dry.. But it'd still b great in a hot green house
 
Josh Golden
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Looks like Douglas fir might work, a well documented awesome tree!
 
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Sounds like an interesting topic for some serious research and experimentation.

What growing zone are you in, Josh? Southern magnolias are evergreen and have deep tap roots, but I don't believe they grow much above zone 6 or so.
 
Josh Golden
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Thanks yeah seems like it's worth some critical thinking and tests.. I'm at the north east border of USA with Canada.. Middle of Michigan lakes..
 
Josh Golden
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Leigh Tate wrote:Sounds like an interesting topic for some serious research and experimentation.

What growing zone are you in, Josh? Southern magnolias are evergreen and have deep tap roots, but I don't believe they grow much above zone 6 or so.



But might they make it in a green house or earth ship...
 
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Many trees are sensitive to the length of days and nights and may not thrive very well out of their zone, even if the temperature is sufficient.
 
Josh Golden
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gary calery wrote:Many trees are sensitive to the length of days and nights and may not thrive very well out of their zone, even if the temperature is sufficient.






Dose Anyone know where to find data about what can Handel the warmth yet changed light? I'd imagin some LEDs would fix it pretty ez, but I know they have internal clocks too..
 
Leigh Tate
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I merged your stuff with the following thread. I hope that is okay by you.
 
Josh Golden
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Plant leafs absorb the sun light and heat, sending it deep into the ground, very much like man made geothermal systems.. Intentionally useing this fact will lead to more efficient systems, from greenhouses to heat and drought resistant growing.. Even shallow roots participate in this energy loop, but obviously deep rooting plants do it much more, while at the same time doing many other vital tasks, from deep water and nutrient recovery, to mining new nutrients out if the rocks, and lowering direct root competition in compact plantings.. Greenhouses would seem to benefit most from this, as well as energy and ecologically friendly homes and cities... Depending on the environment different plants would be used, for example, where its cold evergreens with dark coloring and absorptive patters of living biomass and planting organizations .. Where it's hot lighter plants with wide broad leafs and light blocking biomass and planting orders.. Watering the plants heavily during the peak tempatures can carry the heat difference down, then back up as the plants use it.. Adding a way to adjust the system manually a little..

By the way, these dynamics are responsible for part of the massive night time cooling of earth.. I would expect around 25% of the days heat is stored and the sent into space at night by plants/fungi.. Any information on any of this would be awesome thanks!
 
Leigh Tate
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Josh, I find this topic extremely interesting. Have you run across any studies or research to verify this?
 
pollinator
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I'm not seeing how they are meant to be taking heat down to the ground. most flow in a plant is up from the ground with only small amounts going back down. around 95% of the water a plant takes up is lost via transpiration so that only leaves a maximum of 5% to go back down. Transpiration also causes a lot of cooling of the leaves every liter of water that is evaporated is a loss of 2260kj of energy. and a large tree can use 400l per day.

A very simple test is to stick a thermometer into the ground under some plants and then out in the open, under the plants is cooler, that is one of the major plus points of mulch after all. From my own measurements the temperature under my trees (soil temp) at 10cm depth can be 10C less than in the open soil  and 5C less than under grass. The more plant cover there is the cooler the soil.

Watering plants will cool the air around them due to transpiration and it will cool the soil (if the water is cool of course).

Night time cooling will depend a lot on the local area I doubt one can put a number on it, as it would be dependent on the biomass available, cloud cover, humidity levels etc. Here's a simple experiment, to try; on a still and clear night walk across an open or mowed field and into some woods, you will notice that the woods are warmer, they are warmer because most of the heat loss at night is due to radiation from the grounds surface, the trees are blocking this and keeping the area under them a few degrees warmer than out in the open.
 
pollinator
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My observations concur with Skandi's. We plant things to shade the soil so that it stays cool. If the physics worked this way, the more densely-treed and covered land, the warmer it would be compared to exposed terrain nearby. Dessicated, exposed ground has less thermal capacity than humid soil, but that's only thermal capacity.

Also, wood doesn't conduct heat in the same way that some other substances do. That leaves the water content of the structure, which typically flows up from the roots. What happens when you try to heat a slow trickle of an outflow of water? Will the water upstream get warm? I doubt it, because the medium transporting the heat energy is physically flowing downstream.

For plants to act as geothermal storage, they would have to be far less energy-efficient than they are. I really like Skandi's thermometre smell-check, too.

This isn't to suggest that plants can't thermoregulate to some extent. They sense and react to their environments, and can move their bodily fluids around at need; they may well slow the temperature change at the root zone, where sudden shifts might be disastrous.

But trees in winter go dormant. The ground freezes. So it's not happening there.

I think that taking thermal scans of densely-vegetated boreal, temperate hardwood, sub-tropical, and tropical forests would be a good idea. If there is any merit to this concept, densely treed areas should be hotspots. My personal expectations would be to find that the denser the coverage, the cooler the earth compared to nearby unvegetated terrain.

-CK
 
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