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Situation:

  • Forest
  • Clay Ground covered in pine needles
  • Pacific Northwest Climate
  • No River
  • No Electricity
  • Can provide purified water, and whatever building materials needed.

Goal:

  • Construct a cooler which can permanently serve as an fridge out there.
  • Must be able to keep eggs from spoiling for at least two weeks, and Milk for at least one week.
  • Can't use electricity.

During the spring, winter, and fall; cooling is generally not an issue, living in Canada after-all. The summer here though has proven a bit of a challenge. What I have tried so far, is to keep my milk cold by filling a bucket up with water, and placing my milk in that. It does not work excellently, but I gather it is at least doing something.

I have read that if you dig a hole in the ground, this may be a better way to keep things cool. I am willing to go to just about any extent short of buying a fridge and a generator. The most naturally cold substances I gather would serve as the best means to surround my container.

A solution is needed!

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The folks at Sustainable Living might have ideas as well. –  gerrit Jul 23 at 16:00
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If the eggs have previously been refrigerated they MUST continue to be refrigerated. However, if the egg is fresh and has not been refrigerated they can last weeks in the summer heat. eggs are designed to hatch baby chicks in a healthy environment, eggs only get "rotten" if bacteria has invaded them; they don't just rot from lack of refrigeration, or it would be impossible for hens to hatch chicks. Important to note that you should not wash them once you collect them fresh as there is a protective coating on the egg, wash when ready to consume... –  AM_Hawk Jul 23 at 19:00
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More info on what @AM_Hawk said: cooking.stackexchange.com/questions/14775/… –  nhinkle Jul 23 at 19:22
    
Can I store eggs in a jug full of water? According to this: ca.answers.yahoo.com/question/index?qid=20070704134026AAtYDjp "You can always float them. If you are ever concerned about eggs being good you can gently place them in a container of water. If they sink they are good. If they float up to the top, toss them. They are spoiled. If they are kind of boyiant but still on the bottom they are still good, just older. These eggs boil up and peel perfectly since they membrane seperates more easily." –  Akiva Jul 23 at 20:17

6 Answers 6

The first solution that comes to mind is a "zeer", or pot-in-pot refrigerator. However, this functions best in hot and dry environments as it relies on evaporation to work.

Such a device is constructed by nesting one clay pot inside another, with a layer of sand between them (about an inch on the bottom, a few inches on the sides). The sand is then soaked with water until saturated. The food goes into the inner pot, which can then be covered with a sheet of wet burlap.

A Zeer

"Clay pot cooler - Canari Frigo - Tonkrugkühler" by Peter Rinker - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Clay_pot_cooler_-_Canari_Frigo_-_Tonkrugk%C3%BChler.PNG#mediaviewer/File:Clay_pot_cooler_-_Canari_Frigo_-_Tonkrugk%C3%BChler.PNG

Alternate solutions include an Einstein-Szilard refrigerator, which would require a good bit of skill to construct but only needs a source of heat to power it. Another option is the traditional root cellar. However, it usually requires digging quite deep into the ground to construct a root cellar that will maintain ideal temperatures. You may be able to get somewhat OK results with only a foot or two of soil as the top insulating layer.

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If it relies on hot dry environments, I am afraid I am out of luck. My environment is heavily shaded, from being in the forest, and it is quite humid. Although, I may still consider trying it. –  Akiva Jul 23 at 6:02
    
Another variation that only requires a heat source (e.g. keep some hot coals going) is the Einstein-Szilard refrigerator, but that's probably not going to be straightforward to create: en.wikipedia.org/wiki/Einstein_refrigerator –  requiem Jul 23 at 6:33
    
Looks heavy???? –  Liam Jul 23 at 9:45
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@requiem - If you don't mind lugging around a propane tank, such a refrigerator (a "3-way refrigerator") can be purchased off-the-shelf for a few hundred dollars. –  Compro01 Jul 23 at 18:09
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@Akiva In that case the idea of the barrel-style root cellar sounds useful, as you can go deep enough to get cooler temps. (Yep, saw your other question.) –  requiem Jul 25 at 17:36

Although technology has brought us many conveniences most of them require supporting power or other technology. You seem set on refrigeration and you say: "I am willing to go to just about any extent short of buying a fridge and a generator." Perhaps you should consider solar panels (photovoltaic) and an electric refrigerator. Both technologies are readily available and highly developed. Absorption refrigerators may be less so and they still need a fuel source. (If the refrigerator is well insulated it should stay cold over night if it is not opened.)

A better alternative may be store things that do not require refrigeration, and even your examples are compatible with this:

  • It happens that many people around the world don't refrigerate eggs at all. You may find that undamaged eggs keep just fine for two weeks if stored below ground at a relatively constant temperature.

  • There exists UHT pasteurized milk that may be stored unrefrigerated for a month or more before it is opened.

I believe that hard cheeses can be kept at a cool (cave-like) temperature if tended properly. I'm sure there are many more examples of traditional foodstuffs that do not require modern refrigeration.

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Absorption refrigerators are fairly well developed, at least propane fueled ones. They're been reasonably common equipment in campers and RVs for decades. –  Compro01 Jul 23 at 18:07
    
@Compro01 I spoke out of ignorance. I'll update now. –  Mr.Wizard Jul 23 at 18:34
    
Solar Panels... I may consider this in the future when I build a cabin out there, but in the forest; there just is not enough sun light. –  Akiva Jul 23 at 20:19

You'll need to do several things:

  • Change your habits and foods
  • Work
  • Combine several techniques

First, you need to more carefully consider the necessity of refrigeration. Refrigerators are used to keep food in a "safe" temperature zone where bacteria is less active, and this requires temperatures close to freezing. Passive cooling, such as root cellars and rivers, only reach these temperatures in extreme environments.

If you need to live in a place without refrigeration, it's far easier to change your habits and preserve foods in a way that requires little to no cooling.

Second, cooling methods that will produce refrigerator-like temperatures require a lot of work. Typically that work is obtained from the electrical grid, but since that's restricted in this case, you get to do the work. Digging a root cellar, carrying insulation, and exposing it at night to a cloudless sky with a clear covering for nocturnal cooling, then covering it if it becomes cloudy, or air flow is too great, etc, etc, etc, require a lot of micromanagement. You can, however, obtain freezing temperatures in may places with such a method. It requires a lot of work on your part though - work that could be replaced by a solar panel and thermo-electric cooler, or a small pedal generator where you can contribute work when it's convenient for you, rather than pay attention to the environment and act on changing conditions to best preserve what little cooling you obtain each night.

There are a number of techniques you'll need to know and use depending on the environment. In a humid environment, evaporative cooling won't work well. In a rocky place you're going to have a hard time digging a hole deeply enough for a cellar. In a windy environment you are not going to be able to use nocturnal cooling.

There's no single, universal method that will work everywhere your question is applicable. Combining methods will become necessary in most cases to maximize cooling.

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If your ambient temperatures (air/water/earth) don't get down below refrigerator temperatures (2-4 C), and in summer I suspect they don't, then the second law of thermodynamics says you can't do this without an energy source.

Since electricity is out, you could consider a propane refrigerator.

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You can use the clear night sky as a cold source to get temperatures below freezing -- for thermodynamic purposes, the night sky has a temperature around that of interplanetary space. It requires preventing conductive and convective heat transfer and restricting the directions in which radiative transfer takes place -- a bit tricky, but theoretically doable. –  Mark Jul 24 at 9:43

Because water evaporates at any temperature over 32 DegF, a swamp cooler or evaporative cooler is possible in any climate that needs cooling (though perhaps not in a powerful enough fashion depending on the cooling required). In a still body of water, the evaporation rate is proportional (in some form) to the humidity of the air, the air temperature, the dew point, and the water temperature. Taking all this into mind, here is a simple (unanalysed) design for your consideration:

Dig a shallow trench (the volume of your refrigerator) on the crest of a ridge or hill, or some other location in which you find natural, dry air flow. You will want well insulated walls and floor for this trench, so don't line it with copper plate or anything silly like that. Over the top of the trench you will lay a thin, highly conductive lid like sheet metal. The downward side of this lid should be thinly painted a dark, matte color (to improve radiation from your food to the lid). Once in place, you should poor water onto the lid to create a "roof pond." As the water naturally evaporates from the roof pond into the naturally flowing air, it will cool the chamber underneath it.

This entire pit should be in the shade however, as evaporation due to the water heating from the sunlight will have no benefit.

To create a swamp cooler in this same area, you would need to dig out a (long) channel to let wind into one side of the refrigerator and leave some gaps in the lid for it to escape out the far side, much like a "windcatcher". Pour water into a long hole in the channel, such that the wind flowing into the fridge flows over the surface of the water before entering the fridge. The evaporation of water into the air will drop the air temperature, and you will have cooler air than the outside blowing across your food.

Perhaps the combination of these two ideas would be enough to chill your food to a reasonable temperature? Alternatively, here is a website about passive cooling: http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm#Passive

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This is a great idea. Unfortunately, I am on a nearly completely flat plane. However, being on the coast, the wind does usually blow in a constant direction; could I still utilize this technique? –  Akiva Jul 25 at 20:25
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As long as there is a constant wind, the topography of your area shouldn't make a different. I suggested a ridge simply because they often experience constant airflow. All you need is a source of dry air to evaporate water into, whether it comes on flat ground or a hill makes no difference. Also, if you actually construct a permanent chiller, please post here so that we can hear about your results. –  pheidlauf Jul 28 at 13:25

It there is a well nearby use it. 1. by dropping sealed and floating containers to water and then using a net to get them back. This works very well with beer cans. 2. Put the food in a bucket and use rope to lower it near the water.

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