How to Make a Desert Fridge
How to make a desert fridge or zeer pot
- Problem: Fruit and vegetable storage in hot climates
- Idea: Using the cooling power of evaporation. Two unglazed clay pots placed one in another and a wet sand layer in between.
- Difficulty: Easy
- Price Range: Local price of 2 unglazed clay pots
- Material Needed: 2 unglazed clay pots, sand, water, cloth or lid.
- Geographic Area: Hot and dry climates
- Competencies: None
- How Many people? 1
- How Long does it take? Wet the sand twice a day
You can make a simple and effective cooling container for a dry climate with two clay pots, some sand, a cloth, and a little water. It works thanks the evaporation of water which cools down the inner pot.
One pot needs to fit inside the other with enough space between the two for a layer of sand (a few inches or a bit less than 10 cm thick). The cloth is large enough to cover the top of the largest pot.
Put a layer of sand in the bottom of the larger pot. Set the smaller pot on the sand and fill the gap between the two with more sand, right up to the top. Wet the sand. Put food in the inner pot. Cover the whole with the cloth or a lid.
Wet the sand about twice a day.
The zeer is the brainchild of teacher Mohammed Bah Abba. Bah Abba passed his idea to the Intermediate Technology Development Group (ITDG), which, with the assistance of researchers at the University of Al Fashir, carried out experiments to measure its value in maintaining nutrient content and extending the shelf life of vegetables.
On average, two zeers are used in homes, while women on the market will have three to four.
Zeer Pot. Drawing Khalifa Kamal
- Each zeer can contain 12 kg of vegetables, and costs less than US$2 to produce.
- Experiments show that tomatoes and guavas can be kept for 20 days, compared to just two without.
- Eggplants stay fresh for 27 days.
- Even rocket, which usually lasts only a day before wilting, can be kept for five days.
- It is simple to use and to understand
- For the farmer, the zeer increases sales opportunities
- For the consumer the result is an increased supply of fresh vegetables and fruits in marketplace.
- Iman Mohamed Ibrahim of ITDG says women using the zeer to preserve their vegetables on the market can make an additional 25 to 30 per cent profit on their income.
- It can be used for storing sorghum and millets for a long time, as it protects from humidity when the sand is dry, preventing fungi from developing.
- The zeer can keep water at a temperature of about 15 degree Celsius.
- There is also a health benefit:the zeer helps maintain the vitamin and nutrient content of the vegetables, and prevent disease by keeping flies off the food.
Women's Association for Earthenware Manufacturing in Darfur, with the support of ITDG, is producing and selling zeers for food preservation in the Al Fashir area
See a longer discussion at: http://www.scienceinafrica.co.za/2004/september/refrigeration.htm