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Refrigeration without Electricity? DIY Solutions for Cold Storage

November 21, 2014       How It Works
 ZEER POTS
Indigenous Cold Storage Solutions



In extreme situations, preserving food using indigenous and readily available materials is essential for survival.  Even if you can grow a bounty from your garden, or homestead plots, the food will spoil if you   do not have refrigeration technology that can run without electricity.

That leaves you with canning and air drying or salting, for long term food stocks.  But preserving fresh food for your daily consumption or for barter with other essentials can give you an edge in extreme situations.

Zeer pots were an ancient cooling method re-discovered and popularized in the early 2000s by the Nigerian teacher Mohammed Bah Abba. By manufacturing and mass distributing zeer pots to the poor, the African teacher was able to bring DIY refrigeration / cold storage technology to tens of thousands of impoverished farmers and homemakers, enabling them have a food storage device that kept food safe and consumable for weeks instead of days.



For his efforts, Bah Abba was awarded the $75,000 Rolex Award for Enterprise in 2000 and the World Shell Award for Sustainable Development in 2001.

The Nigerian has a fluorishing micro-enterprise selling about 30,000 Zeer per year for 200 Nigerian naira ($1.30) a piece.


How the ZEER POT Works:

You only need a glazed earthenware pot nested inside a larger, porous one with a layer of wet sand separating them.   Place the smaller pot inside the larger porous one and fill the space between both pots with clean wet sand.  When the water evaporates through the outer pots porous surface, this facilitates a cooling down of the inner pot just like a refrigerator.  This process can keep up to 12kg food fresh for as long as three to four weeks without using power from the grid.



Peter Rinker                         Creative Commons  CC BY-SA 3.0


When placed in a shaded, breezy location, the evaporation of water off the outer surface chills the pot. If you have a good breeze, or a fan powered by a solar panel blowing the pot, the pot can get quite cold. Imagine that chill you get when you step out of a pool when the wind is blowing. Now imagine that wet wind chill going on all day and cooling your food and keeping it fresh. 





Why It Matters


For any food or produce in extremely dry and warm heat like in Africa where the tech was developed, there is no such thing as a shelf life. Fresh fruit and vegetables last maybe a day or two, and meat spoils within hours. This means that most food must be either sold or consumed immediately. Having storage technology that also preserves food allows the locals to spend more time doing essential things like studying for school instead of constantly preparing meals or going to the market to get their daily meal before it spoils.

Farmers can store their produce harvest for longer with cooling storage that can function effectively off the grid.  They don't have to sell their harvest immediately.   Even temperature sensitive medicines can be kept at hand in ZEER pots to save lives when diseases break out.

If you think the almighty Grid can withstand any extreme situation and allow your community to recover, think again.  This technology is made freely available and most advocacy groups teach it to low income local indigent communities as a way of coping with lack of electricity.  You can avail of it as an emergency storage technology or use it to get used to living off the grid.  Using the technology efficiently allows you to keep yourself stable and flexible with any temporary or long term extreme situation.


How to Build a ZEER POT:

Materials and Tools Required

  • Two terra cotta pots with a 2-3 inch difference in diameter. The smaller pot should be glazed and preferably lacking a drainage hole. If the inner container is double glazed (on its inner and outer walls), non-potable water—say seawater—can be employed.
  • a bag of sterile sand
  • a square of burlap cloth large enough to cover the top of the inner pot
  • a trowel

Keep Away from High Humidity or Direct Sunlight

The ZEER Pot won't work as well in high humidity.  High humidity results in much less evaporative cooling and the pot may even be absorbing ambient heat in very warm places.  Humidity may also cause bacteria and fungi to grow in the wet parts of the pot so this is something to consider—keep the pot in a well-ventilated area to avoid this problem.  Direct sunlight cancels all cooling effects and you must rely on wind-induced evaporation, not from evaporation due to sun exposure. Direct sunlight will heat up the clay and the sand.  Keep your ZEER pot in a cool dry place away from direct sunlight.

Medium sized zeer pots work better than one giant ZEER pot because the higher volume of contents in a larger pot take longer to cool down.     Your food also absorbs cold and the more food to chill sitting in one pot, the less effective it will work for practical purposes. Several smaller ZEER work better than one or two large ZEER pots.

The original specs allowed for up to 12kg. of food to be cooled down in one ZEER pot but this is because Africa is an arid dry and windy environment as opposed to a more humid Asian climate.

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