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Old 11-18-2008, 05:45 AM   #1
Baggywrinkle
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Default Refrigeration without electricity; zeer pots

Part I) Passive Cooling and Zeer Pots
By Scott A. Meister

If you happen to live in an area that depends on a lot of electricity, and you’re finding electricity to be rather expensive...or would rather wisely eliminate as much of that expense as possible so you could spend your hard earned money on other things, then you need to be looking for ways to reduce or eliminate your electrical use as much as possible. Where can we cut our electric bills?

We’ve all heard of changing our lightbulbs to the new and improved warm fluorescents (no, they no longer turn your skin green). Of course, we can shut off our lights when we’re not in a room, shut off all electrical appliances we aren’t actually using. After all, there’s really no need to have all the lights on in the house, the stereo blazing and the TV on with no sound while we browse the internet. Those kinds of things are easy to see, and cutting back on them does a lot of good. But a large portion of the energy going into a household is actually used for heating and cooling rooms, food and beverages.

Even if you think you’re rich enough to waste your money on electricity, you still need to be concerned about emergency situations when the power companies stop giving you what you need. If you lived through the LA blackouts as I did...then you know what I mean. Believe it or not...there are a number of free and effective ways to nip your electrical cooling bill in the bud while also be prepared for power-outages.

We can consider passive solar cooling and air-conditioning. Please note that we are not talking about the use of photovoltaic solar panels, those are active solar devices. I’m talking about passive solar cooling. A lot of people have trouble imagining that the hot summer sun, can actually cool your house, but it can. The second law of thermodynamics is our best friend, and it works endlessly for free (or at least as long as the sun exists).

Heat rises (in the case of hot air), heat can radiates outward from warm surfaces, and heat will always move toward cooler areas, and if it happens to draw liquid with it, and that liquid evaporates...the inside surface of what just evaporated will be cooler. Solar chimneys, underground cool rooms (the old fashioned cellar), and the zeer pot, are just a few ways that use these aspects to our advantage to help us cut our power needs forever, and for free. After all, isn’t that what we all want? Why should we slave away at work all day and then spend our hard earned money on things that we can get for free?



To the surprise of many, the world’s cheapest refrigerator/cooler costs less than $2 dollars to make, uses minimal resources to produce and runs completely without electricity. It’s called a zeer pot, or the pot-in-pot and was developed by Mohammed Bah Abba, who realized that he could put the second law of thermodynamics and transpiration to work for him. The zeer pot, is actually two earthenware pots (I’m assuming they are both unglazed), one pot smaller than the other. The smaller pot is put inside the bigger pot, and the space in-between them is filled with sand. The sand is made wet with water (twice a day) and a wet towel is put on top of the two pots to keep warm air from entering the interior. As water in the sand evaporates through the surface of the outer pot, it carries heat, drawing it away from the inner core, thus cooling the inside of the inner pot which can be filled with soft-drinks, water, fresh fruit, vegetables or even meat. A damp cloth placed on top keeps the inside pot away from hot air. In this way, fresh produce can be kept for long periods of time without the need for electricity, or camping coolers made high embodied energy. Tomatoes and peppers will last for up to three weeks, and African spinach, or rocket, which normally would spoil after just a day in the intense African heat, can and will remain edible for up to twelve days. Eggplants will keep for up to 27 days instead of three. It can even be used for storing sorghum and millets for a long time since it protects from humidity, thus preventing fungi from developing. The zeer will keep water (and other liquid beverages) at about 15 degrees Celsius (maybe acceptable for Guinness), and even meat can be kept fresh for long periods.



The new technology is now being used by farmers at the market. Fresh produce is kept inside, with just a couple fresh items displayed on the damp towel resting on top.



In this way, most of the produce is kept hidden away from both warm air and insects. In the past, all produce was displayed in the open air, attracting flies resulting in stomach disease such as dysentery. Now food can be kept fresh for longer and kept away from flies...even miles away from electricity or ice. The key however, is a certain degree of aridness, for at a certain amount of humidity, the benefit of evaporative cooling tends to dissappear.

Although many people are excited about promoting this technology in developing countries, I see greater potential for this technology in the developed western cities, suburbs and countryside.

Instead of having humming, heat producing, electrical, bank-sapping refrigerators and freezers, we could have zeer pots stashed away in or near the garden, by the back door, out on the porch or balcony...anywhere. We could have them on the truckbeds of roadside vegetable stands, in cross-country delivery vehicles...at the local farmer’s market. We no longer have to make choices about freshness based on expensive camping coolers, refrigerated trucks, ice machines and electrical outlets. We can provide our own endless supply of refrigeration for less than two dollars.

http://permaculturetokyo.blogspot.co...e-cooling.html

For further information on zeer pots, please see the following sites:


http://www.slashfood.com/2006/09/28/...that-zeer-pot/

http://www.scidev.net/features/index...315&language=1

http://www.wikihow.com/Make-a-Pot-in-a-Pot-Refrigerator

Last edited by Baggywrinkle; 11-18-2008 at 05:49 AM.
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Old 11-18-2008, 06:14 AM   #2
whitecrow
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Default Re: Refrigeration without electricity; zeer pots

I'm amazed and delighted to learn about the zeer pot! Thank you!
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