Mohammed Bah Abba, a teacher in rural Nigeria developed the Pot-in-Pot Preservation Cooling System that keeps food and medicine fresh by storing them in two clay pots. The system requires no electricity to preserve and prolong the storage life of perishable items in hot climates.
The design is very simple, made up of two earthenware pots which utilize the principles of evaporation to create electric-free refrigeration. In between the two pots is a layer of fine, wet river sand, and on top is a moist jute bag. When kept in a dry, well-ventilated, and shady location, water evaporates, cooling the inner container.
This allows produce to stay fresh for weeks, so less food is wasted, and farmers are able to increase their profits so that they can continue to provide for their communities without fearing spoilage. Additionally, it provides storage for vaccines and medicines that would otherwise be unavailable in areas without refrigeration facilities.
Mobah Rural Horizons, a Rural Development and Consulting Organization designs, invents, and disseminates appropriate technologies for poor rural areas.
You can also watch this video to learn more and easily make your own cooler: