Appropriate Technology: Refrigeration in the Desert

Appropriate Technology: Refrigeration in the Desert

Many people, largely in Africa, must depend upon subsistence farming (http://en.wikipedia.org/wiki/Subsistence_farming) to feed their families and eke out a meager living. These communities are usually extremely isolated from the outside world and lack access to electricity. That makes refrigeration of perishable food very difficult, and the consumption of spoiled food is a major cause of disease in the developing world.

A young Nigerian teacher, Mohammad Bah Abba (http://www.rolexawards.com/laureates/laureate-6-bah_abba.html), invented a solution for isolated desert families that allows them to keep food and beverages cool, giving them a longer shelf life. The device is called a Zeer, or pot-in-pot refrigerator (http://en.wikipedia.org/wiki/Pot-in-pot_refrigerator), and it utilizes the laws of physics to keep its contents cool.

The Zeer is simply two clay pots of different sizes, designed so that one fits inside the other. A layer of sand is placed between the two pots and kept wet. A damp cloth is placed over the mouth of the Zeer to keep in cool air and prevent insects and predators from contaminating the contents.

The drier external air circulates around the larger pot, drawing moisture toward the outer wall and lowering the inside temperature by several degrees. As long as the sand is kept damp, certain vegetables such as tomatoes and peppers can last up to a month.

Rolex recognized Bah Abba’s accomplishments when the company selected him to be the Rolex Laureat (www.rolexawards.com/special-feature/inventions/abba.html) in 2000. The Zeer requires no outside energy or heat source, and is inexpensively made with materials readily found in rural farming communities.

The artful use of clay pots for cooling dates back to Egyptian times, when people used them to store food and water. They even used a larger version as a sort of coffin to store human remains. As with many appropriate technologies being developed today, we can study the practices of ancient humans. After all, they certainly lived in isolated communities without plumbing or electricity.

The pot-in-pot unit is very affordable, running at only $2 for the small version and $4 for the larger Zeer. Bah Abba has supplied local Nigerian villages with more than 12,000 Zeers with money out of his own pocket.

Friday, February 16, 2007