In 1995, Mohammed Bah Abba, a teacher from northern Nigeria, invented the Pot-in-Pot preservation cooling system also known as Zeer pot cold storage. His design consists of five simple items: – two clay pots, sand, water and a cloth cover. By combining these simple items Mohammed produced a cool chamber or refrigerator for desert regions which have little or no access to electricity.
Cold Storage No Electricity
The Zeer pot cold storage works by placing the small clay pot inside the large clay pot. Fill the space between the two pots with sand. Wet the sand with water, then cover the whole thing with a wet cloth. This clay pot refrigeration system works similarly to sweat. When the water in the sand evaporates it draws the heat away from the inner pot. Therefore, we can observe up to 10ºC difference between the temperature inside the inner pot and the ambient temperature.
Food such as eggplant, peppers and tomatoes stored in these Pot-in-Pot refrigerators can last up to 3 weeks instead of 2 to 3 days. Furthermore, the Pot-in-Pot protects food from being contaminated or eaten by insects and animals. This clever design incorporates traditional craftsmanship and natural local materials.
In the video below, Mohammed explains the assembly of his invention.
In 2018, MIT D-Lab collaborated with World Vegetable Center and Movement e.V. in Mali and Burkina Faso. These partnerships studied and compared various clay evaporative cooling chambers such as the Pot-in-Pot. The studies produced a decision making tool, guidance on optimal storage conditions for fruits and vegetables as well as a best practices guide. These studies detail how often the pots should be watered. Additionally, whether the fruit or vegetable produces or is sensitive to ethylene. Ethylene is a natural plant hormone and a gas. It is released by some fruits as they ripen, accelerating the ripening process of produce (fruit, vegetables and flowers) that are sensitive to it. However, the specific conditions to effectively operate an evaporative cooling chamber include low humidity, high temperature, access to water and a shady, well-ventilated location.
Overall, Mohammed Bah Abba’s invention provides economic, environmental, and educational assistance to reduce food waste, especially in rural desert regions.