Mitti Cool

The Pot-in-pot Cooler, based on by ancient techniques, was designed by Mohammed Bah Abba who won the Rolex prize and who has been promoting this process though-out Nigeria. The concept takes advantage of evaporative cooling.

Pot-in-pot Cooler

The system works by fitting a lidded earthenware pot inside a larger pot with the space in between, filled with sand and water. The sand layer can be kept cool by adding water generally twice a day, thus providing refrigerated storage space at minimal cost.

When that water evaporates, it pulls heat from the interior of the smaller pot, in which vegetables and fruits can be kept. As water in the sand evaporates through the surface of the outer pot, it carries heat, drawing it away from the inner core, thus cooling the inside of the inner pot.

The Clay refrigerator enables tomatoes to last for twenty-one days, rather than two or three days–without this technology. It has proved very efficient and it has been tested with a number of different vegetables.

The same principle was applied by Mansukhbhai Raghavbhai Prajapati, a potter from Wankaner in Gujarat. He designed a fridge for the common man that does not require electricity and keeps food fresh too. With this basic premise in mind Mansukhbhai came up with Mitticool, a fridge made of clay. It works on the principle of evaporation. Water from the upper chambers drips down the side, taking heat from the inside gets evaporated, leaving the chambers cool. Cool and affordable, this is the option to keep food, vegetables and even milk fresh naturally for days.

Mitti Cool Fridge

Prajapati has come up with an innovative apparatus that functions like a refrigerator: It cools drinking water and can store vegetables for days on end without electricity. Made of clay, the 'fridge' has a 10-litre water tank at the top while the lower part has a chamber which can be used to store vegetables or other eatables that need cooling. His innovation is being supported by NIF and GIAN. 

After more than three years of continuous efforts and failures, in 2004 Prajapati's clay fridge model worked successfully. He called his product 'Mitticool.' The device works on the principle of evaporation. As the water evaporates through the pores of the clay, it not only cools the water itself, but also the lower chamber and its contents too.

Food preservation is one of the biggest problems in the rural areas, where farmers lack water, electricity and transportation. The harsh climates in several countries make it impossible for farmers to preserve their crops for more than three days. Beyond what they may eat and trade in their communities, the time works against them and they are losing the opportunity to sell the harvest at the market, hence missing an important source of income. Sometimes the market is located several miles away from their villages.

This is a very good alternative for the rural people who can not afford the conventional refrigerator due to high initial cost and its maintenance cost. Educating to less developed countries how to create Mitti Cools and Pot-in-Pot coolers should be encouraged to clay makers in rural areas so that these people are aware of this design and can use and benefit from it too. Examples of some of these regions are Nigeria and India.