Almost free refrigeration using earthenware pots: A radical innovation for peasants

Refrigerator is very expensive?? no problem. Purchase a Zeer (see the picture). Mohammed Bah Abba is a grass-root innovator who invented this pot-in-pot cooling system and now, it has become extremely popular in many african countries, including his native country, Nigeria.

Science part comes here:

The pot-in-pot consists of two earthenware pots of different diameters, one placed inside the other. The space between the two pots is filled with wet sand that is kept constantly moist, thereby keeping both pots damp (slightly wet). Fruit, vegetables and other items such as soft drinks are put in the smaller inner pot, which is covered with a damp cloth. The phenomenon that occurs is based on a simple principle of physics: the water contained in the sand between the two pots evaporates towards the outer surface of the larger pot where the drier outside air is circulating. By virtue of the laws of thermodynamics, the evaporation process automatically causes a drop in temperature of several degrees, cooling the inner container, destroying harmful micro-organisms and preserving the perishable foods inside.

Now coming to the developmental economics, every year many farmers all over India, due to lack of proper preservation systems, sell their produce at throw-away prices. It is true and in fact, I was grown-up my whole life listening to those horrible stories such as 1 Kg of vegetables for 15 Paise (0.01 USD) or 25 paise. Then the farmers throw them on highways as they cant fetch the price of transport. Surprisingly, at the same time, in a 100 KM near-by vegetable market in any town/city is sold at Rs. 20 per KG. There are many reasons for this unbelievable difference in the price. Some of these are:

1. Farmers take loans for the purchase of seeds, pesticides, health issues, family ceremonies etc from local people who pressure up for repayment as soon as the crop is ready for sale. (Possible solution for this issue is institutionalized micro-finance)
2. They don't have preservation systems. (This is where, possibly, Pot-in-Pot system would be helpful)
3. They are often mislead by middlemen. (Update of market prices would be greatly helpful, and many telecom companies are working on this)
4. Farmers don't have enough investment to take it to the near-by city market. (ITC e-Choupal kind of systems are helpful in this regard ).
   

Clearly this is a business opportunity to sell these pots in various sizes. Anyone listening there?