In North America, we have become completely reliant upon electricity in virtually every aspect of our lives.
The supply of electricity has expanded to meet the demands in most areas and is exceedingly reliable.
Where would we be without the washing machine, furnace, and smart phone?
There are times, however, when the power goes down or we run out of room in the refrigerator. And of course there are some people who are becoming more environmentally conscious and want to be more self-sufficient.
Ancient Technology for Modern Times
In parts of Africa where refrigerators and electricity are non-existent, farmers use an ancient technology to store produce that works as well as any Maytag.
The zeer pot is also called a pot-in-pot and is, in modern terminology, an evaporative refrigerator. The way it works is explained by simple science and anyone can make one for personal use.
Making a zeer pot is as as easy as this:
1. Take two large earthenware pots, one about an inch larger in diameter than the other. If there is a hole in the bottom, plug with a piece of clay or cork.
2. Put a layer of sand in the bottom of the larger pot.
3. Place the smaller pot inside the larger. The layer of sand needs to be thick enough for the two pots to end up about the same height.
4. Carefully fill between the pots with sand.
5. Pour water on the sand until it can’t absorb any more.
6. Cover with a damp cloth.
7. Check the water and the cloth regularly–you’ll need to refill about twice a day.
8. Keep in a dry, well-ventilated space.
The pots must be able to breathe for evaporation to take place; a natural material is therefore required–plastic won’t work.
How It Works
What happens is that the water in the sand evaporates, cooling the inner pot (and whatever is inside it).
You can store fruits, vegetables, water, or anything you want to keep cool. The contents won’t be as cold as a refrigerator but cool enough to keep things fresh.
The sand between the pots must be kept moist to keep evaporation constant. A zeer pot may be preferable for storing produce because refrigeration at low temperatures can speed the loss of nutrients in fresh fruits and vegetables.
The inside temperature of the pot is dependent upon the outside temperature and relative humidity:
Conditions under which an evaporative refrigerator could reach 6°C (43°F)
Outside Temperature Relative Humidity
20.5°C (69°F) 0%
18.3°C (65°F ) 10%
15.3°C (59°F ) 20%
13.3°C (56°F ) 30%
12.2°C (54°F ) 40%
10.5°C (51°F ) 50%
So while no one is running to ditch all electric conveniences, simple, practical, and affordable solutions for modern-day needs do exist.