Solar powered "root cellar"

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not enough of a hill, more just s shallow slope grade(1':30'+/-)... good thing about advance planning is you get to "measure twice, cut once"... trying to hold this down to under $4K..just bouncing the ideas around now
I did a whole post with pictures of the root cellar I built. I didn’t have anywhere near 4 grand in it but did have a lot of my labor and time on the weekends. It’s in the old threads here.
 
Texas
1. Near Nacogdoches.... no bedrock
2. 10'+ depth earth is stable 70 degree temp +/- 5 degrees in our area
3. difference between need and want I guess . this would give me approx 500 cf storage
4. anything that last longer with dry, dark, cool storage from garden veggies to LTS freeze dried canned goods
5. not Staying down there at all. just storing and retrieving... minutes per usage

Norwesco Bruiser Single Compartment septic tanks are one piece moulded plastic. Designed reinforced to be buried w/o filling full of water. Mainly wondering it would defeat the purpose to have surface air being drawn down into and environment that should already be cooler due to surrounding ground temp at 10' depth. Water table around 25' down in my location.

The fan would be mounted at the bottom of the hot air evac vent pipe down n the tank. The power wire would be fed up the vent to a solar panel on the surface.. Sun shine, fan works... no on/off. forcing the air in the tank up and out the top and resulting in the intake vent drawing in the outside surface air into the tank.

BUT in our summers that air may be at a higher temp than the air in the tank 10' below ground. I am just starting to think this through now and solve the problem foreseeing any drawbacks. Maybe install a on/off switch on the fan, turning it off in the summer and on in the winter? IDK maybe I am overthinking this... I tend to do that sometimes. It is the curse of my profession :)

PS the cost is excavating and filling the hole ( 1 day on excavator) and the two 1500 gal plastic septic tanks. Solar would probably be less than $150// too old for the do-it-yourself route

PPS running the intake vent pipe approach is interesting
 
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Need a little advice from you root cellar people. In about 6-12 months my acreage should have everything ready for 2nd stage prepping to begin (root cellar, Garden, etc). Phase 1 is solar water, solar refrigeration, septic, fruit trees, large travel trailer, misc. fencing and catfish stocked ponds...

but I would like comments on what I plan for cool LT food storage. I plan on burying two Norwesco Bruiser Single Compartment septic tanks (11' x 4.5' x 5.5' high). Installing air vent hook pipes to promote air flow with insect screens and assist the flow with a little solar powered fan forcing hot air (high vent) out, thereby creating a vacuum effect in the tank bringing in cooler air. (As cool as it can get in Texas)

Do any of you with experience see any problems with this concept? I freely admit I am out of my depth on root cellars! or any other cooling methods that do not require heavy (A/C) techniques.

Any advice is appreciated
The septic tank should already have 2 holes for ventilation, that being the inlet and outlet holes for the septic lines. Although both holes are usually high so you may need to drill one for the lower pipe. You can rent a core drill from Home Depot and they are easy to core drill, I use to cut concrete for a living and cored many a septic tanks! For having to lower your food down in them, see is you can attach a ladder in one of the maintenance holes. I have actually thought about putting another septic tank next to my "real" septic tank and store some of my preps in it, especially guns, so if big brother came knocking, it would just seem like another septic tank. Even if you bury it deep, you can install a metal box, the size or a little bigger, than the maintenance hole you plan on using. Sit it over the lid, have a top for the box, then cover that up with just a few inches of dirt to hide it. You then will not need to dig that deep to reach the lid.
TexasFreedom had a good idea on running the pipe a good ways. It will help cool the air but also keep eyes away from the actual location! maybe even put it in thick of trees, shrubs or I have even seen a guy who used a ventilation pipe as the base for a big bird house!
 
Texas
1. Near Nacogdoches.... no bedrock
2. 10'+ depth earth is stable 70 degree temp +/- 5 degrees in our area
3. difference between need and want I guess . this would give me approx 500 cf storage
4. anything that last longer with dry, dark, cool storage from garden veggies to LTS freeze dried canned goods
5. not Staying down there at all. just storing and retrieving... minutes per usage

Norwesco Bruiser Single Compartment septic tanks are one piece moulded plastic. Designed reinforced to be buried w/o filling full of water. Mainly wondering it would defeat the purpose to have surface air being drawn down into and environment that should already be cooler due to surrounding ground temp at 10' depth. Water table around 25' down in my location.

The fan would be mounted at the bottom of the hot air evac vent pipe down n the tank. The power wire would be fed up the vent to a solar panel on the surface.. Sun shine, fan works... no on/off. forcing the air in the tank up and out the top and resulting in the intake vent drawing in the outside surface air into the tank.

BUT in our summers that air may be at a higher temp than the air in the tank 10' below ground. I am just starting to think this through now and solve the problem foreseeing any drawbacks. Maybe install a on/off switch on the fan, turning it off in the summer and on in the winter? IDK maybe I am overthinking this... I tend to do that sometimes. It is the curse of my profession :)

PS the cost is excavating and filling the hole ( 1 day on excavator) and the two 1500 gal plastic septic tanks. Solar would probably be less than $150// too old for the do-it-yourself route
Didn't know they were plastic, disregard the core drilling part! :eek:
 
My fault, I wasn't descriptive enough. We have been getting away from old concrete septic tanks around here for few years now. We can get the plastic ones pretty cheap, but you have to fill them up with water before backfilling (except for the Bruiser tanks I cited)...A 500 gallon non-reinforced plastic septic tank (must fill with water before backfilling) is only $650..... beats the hell out of a 500 gal concrete tank!..... of course you must make sure you aren't in expansive clay territory! these are good for sandy loamy conditions

PS.. Texas might just be on to something running that intake horizontal at depth allowing the outside air to be cooled before it enters the tank. I hadnt thought of that
 
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So the power just connects directly to your existing main panel with nothing else in-between?! Is this because the microcontrollers stop sending power when city power goes out?
 
My fault, I wasn't descriptive enough. We have been getting away from old concrete septic tanks around here for few years now. We can get the plastic ones pretty cheap, but you have to fill them up with water before backfilling (except for the Bruiser tanks I cited)...A 500 gallon non-reinforced plastic septic tank (must fill with water before backfilling) is only $650..... beats the hell out of a 500 gal concrete tank!..... of course you must make sure you aren't in expansive clay territory! these are good for sandy loamy conditions

PS.. Texas might just be on to something running that intake horizontal at depth allowing the outside air to be cooled before it enters the tank. I hadnt thought of that

The reason you have to fill them is that the water gives a counter-pressure to support the walls. If you ever empty the tank, it has a real risk of collapsing. Oops. Reconsider concrete,

The horizontal pipe absolutely works, a friend with an underground house uses that idea with good success. Don't drill extra hold, put an 'adapter from the existing intake and just add a pipe inside to take your incoming air to floor level.

No reason to go 10 ft deep, is there? 2-3 ft of soil on top should be plenty. If worried about heat coming down, put a sheet of foam insulation on top and cover that with a sheet of FRP or even better aluminum. You will kiss this old ugly man if you have to go down/up 100 times (10 ft fs 3 ft).
 
Yeah That is the reason why I am NOT going with non reinforced plastic tanks, I kind thought the freeze dried stuff and veggies might get a little soggy.
Dont think I'll need to access that often and that's what the rest of my family is for anywho.

Tanks:
https://www.norwesco.com/products/waste-water-tanks/bruiser-tanks
PS.. I'll be burying my actual septic tank this summer, so I will get to see the soil temps at depth in the height of the hot season. I'll see then what 6' down reading on the thermometer
 
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............

The horizontal pipe absolutely works, a friend with an underground house uses that idea with good success. Don't drill extra hold, put an 'adapter from the existing intake and just add a pipe inside to take your incoming air to floor level............

When you first mentioned it, I envisioned exactly that hook-up. Damn good idea I think
 
Yeah That is the reason why I am NOT going with non reinforced plastic tanks, I kind thought the freeze dried stuff and veggies might get a little soggy.
Dont think I'll need to access that often and that's what the rest of my family is for anywho.

Tanks:
https://www.norwesco.com/products/waste-water-tanks/bruiser-tanks
PS.. I'll be burying my actual septic tank this summer, so I will get to see the soil temps at depth in the height of the hot season. I'll see then what 6' down reading on the thermometer

You might want to verify why this statement is on their website:

  • Once in the ground, must be kept 1/4 full at all times.
It may be to just prevent it from floating up in heavy rains (ok). It may be to support the walls (bad)
 
Yeah... that is for weight because the Tank is so light. I am going to check with the manufacturer, but in unstable water tables in sandy soils, it may experience flotation if not weighted down. Water table will never rise as high as the elevation I am thinking of installing. Definitely will check on that before my final decision, might have to weight the floor down with something if I decide to go this way.
 
Yeah That is the reason why I am NOT going with non reinforced plastic tanks, I kind thought the freeze dried stuff and veggies might get a little soggy.
Dont think I'll need to access that often and that's what the rest of my family is for anywho.

Tanks:
https://www.norwesco.com/products/waste-water-tanks/bruiser-tanks
PS.. I'll be burying my actual septic tank this summer, so I will get to see the soil temps at depth in the height of the hot season. I'll see then what 6' down reading on the thermometer
Any update on your progress @David SB ? Would love to hear about it. We are still trying to figure out how to do a root cellar on our property.
 
This is a hodge podge of topics, but one of the key aspects of this is the solar powered. I would like to be a very well insulated room on a 8'x14-16' flatbed trailer to serve as an above ground root cellar. Walls and floor will be r-30, ceiling r-50. It will very likely be pretty noise proof also. At first I was thinking of putting a chest freezer or two inside with a new thermostat set to 50 degrees. Option 2 is to not use chest freezers inside - unless it is actually to freeze something but to keep the entire room chilled to 50 degrees. Chilling would be done with 2 window a/c. One is probably enough for this size room, but the second one would serve as a backup. I have seen "thermostats" that make an a/c function as a freezer in a walk in unit. Basic, absolutely must requirement: to be able to power this thing from the sun. Do you think 72 sq. ft of solar panels can make this work? I would put batteries in for 2 days of operation, but really, when the sun doesn't shine, it is usually not so hot, so the a/c would not be in use. Any suggestions? A stupid idea? I will not be in a position to consider underground or in ground storage for the next 3 years, but I want to reach my food lts goals in about 3 years.
I dont think that 72.5 sqft are sufficient, but it depends on how many kwh you consume in your cellar. Solar panels take roughly 18 sqft per panel, so with 72.5 sqft you will have a yield of about 1.5kWh (source). If youre planning to live down there with your family, you will probably need something bigger.

For comparison, a family of three needs about 20-30kWh per day (depending on where you live of course), so in that case you will need something like three times that size.
 

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