Wednesday, May 28, 2008

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?


Never Mind!! said...

The pot in pot is an interesting concept for personal use. Has this been used at a full scale level? I mean at a scale where farmers can preserve their produce?

This is my first time at your blog.Came here from Desipundit and you have a nice blog!

tsp said...

Really interesting idea.

But just wondering - How long can they refrigerate using this method?

Vivek Tulsidas said...

Came to your blog through DesiPundit.

Nice idea.
Actually looks more like an idea that has stemmed from some interesting school project.

But the people who have commented here have raised some pretty valid questions.

JRK said...

Came through Desi Pundit ...
You are wrong in stating that this has not been tried in India ...
There is a potter in Gujarat who uses Clay to make an Electricity Free fridge that can cool upto 5 litres of water and preserve vegetables for over a day or 2 ...

Malapati Raja Sekhar said...


It is being sold in African countries to many farmers. Bah Abba, the inventor, has been trying to promote in many countries in Africa among farmers.

@TSP, vegetables can be preserved for about 20 days in this natural-cooling system.

here are the responses to the others' comments.

sunil said...

hai raja, This is sunil madan, came across you rblog while seaqrching on rural education in india. I like your thoughts. keep it up. I am working in private research organization, and paralley planing to start primary english school in my village , as i see tehre is no english school arount 20 km. There is huge talent lying in villages, need to bring them to feed global need.
keep in touch

Sunil madan.

srinivas said...

Looks like your blog doesn't have feed that I can subscribe to.
You have feed for comments though.

Malapati Raja Sekhar said...

@srinivas, is the feed url.


Pavani Valluru said...


You are maintaining very good information in your blog.
about the real issues, causes and other solutions, I like your approach.

Keep it up.


The Doors Of Perception said...

Sad to see the developed world now fobbing off the little innovations that developing world produces. This girl is now claiming to have invented the "solar-powered-fridge"

Social Entrepreneur said...


Do you know if anyone is producing this product in India?

Also, if someone produces, how successful would it be. Do farmers really need it?