Mohammed Bah Abba, Mobah Rural Horizons
Zeer Pot is a simple fridge made of local materials consisting of one earthenware pot set inside another.
Mobah Rural Horizons and Practical Action
Janata Cooler, Bamboo Cooler, Almirah Cooler, Charcoal Cooler, Static Cooling Chambers, Naya Cellar Storage, Solar Powered Refrigerators. The Desert Fridge, one of the closest competitors, is distributed by Humanity First.
Goal 2: improve food security and nutrition by preventing of gastrointestinal issues due to poorly preserved food.
Off-grid, rural communities dependent on subsistence farming. Produce spoilage causes disease and loss of income for needy farmers and venders who are forced to ‘rush sell’ most agricultural products, even though they are well aware of the negative impact flooding the market has on their profits. Even in towns and cities where erratic power supply is available, most of the urban poor cannot afford refrigerators.
Most groups providing Zeer Refrigeration depend on individual and local manufacturers. Mobah Rural Horizons produced on average 30,000 Zeer Pots as of 2005.
Mobah Rural Horizons is the main distributor. Implementation of evaporative cooling refrigeration has been demonstrated throughout Nigeria, Darfur, Sudan, Chad, the Democratic Republic of the Congo, Niger Republic, and Cameroon. Majority of production located in Kano, Jigawa, Borno, Yobe, Sokoto, Zamfara, Kebbi and Katsina States, all in the northern region of Nigeria.
Unknown, but a production capacity of 30,000/year is claimed
The underlying principle behind the Zeer Pot is that as water evaporates it will remove heat from it’s surroundings. To take advantage of the evaporative cooling effect, take two earthen pots of the same shape but different sizes, put one within the other, fill the space between the them with sand and pour water into the same cavity (or other substrate e.g. coconut fiber) to make the sand wet. The result is that when you place food items into the inner pot, cover with a lid or damp cloth you can keep the temperature up to 10 degrees cooler than the external environment. Store the pot-in-pot refrigerator in a dry, well-ventilated space; and let the laws of thermodynamics do the rest. As the moisture in the sand evaporates, it draws heat away from the inner pot, cooling its contents. The only maintenance required is the addition of more water, around twice a day.
Detailed schematics available here. See image below.
Zeer pots designs are open-source. Technical support can be provided by the local manufacturer (ex. local artisan or potter).
Zeer pots designs are open-source. If a pot is broken, it should be simple to replicate with a local artisan and potter.
Zeer pots last until contaminated or damaged at which point they can be used for cooking bowls or returned to soil and can be used to make new clay based products.
• Minimum internal temperature of 15ºC
• Storage volume for 12kg of fruit and vegetables
• Consumes 1.5 – 2.5 L water/day
Practical Action conducted testing. Recommends that performance evaluation should include average internal temperature for given humidity and external temperatures. Average number of days before produce spoils compared to without refrigeration (shelf life) increased up to 5x: tomatoes, guavas and carrots last 20 days, okra lasts 17 days and rocket lasts 5 days with the refrigerator as opposed to 2-4 days.
Individual ceramic refrigerators do not seem to be tested as they are made locally. However research has been done to prove effectiveness of the ceramic refrigeration.
The only risks associated with evaporative cooling is possible contamination and spoiling of foods; however, this is already a threat to produce and the zeer pot serves to reduce rate of decay and frequency of contamination. It must be understood though that use of evaporative cooling refrigerators may not be effective in all conditions and environments and this is especially important if it is used to store vaccines and other medicines. Users may require some education about maintenance and ideal storage for them to be effective.
Technologies related to creating clean fuel sources for when firing the pots, sourcing clay and those that ensure that the community has a ready source of water for evaporative cooling (e.g. hand-powered well digging rig).
Odesola, I. F., Onyebuchi, O., A review of porous evaporative cooling for the preservation of fruits and vegetables. The Pacific Journal of Science and Technology. 2009 Nov;10(2):935-941.
Basediya, A. I., Samuel, D. V. K., Veera, V., Evaporative cooling system for storage of fruits and vegetables – a review. Journal of Food Science and Technology. 2013 Jun;50(3):429-442.
Anyanwu, E. E., Design and measured performance of a porous evaporative cooler for preservation of fruits and vegetables.Energy Conversion and Management. 2004 Aug;45(13-14):2187-2195.
Awards received include 2000 Rolex Awards, 2006 Tech Museum of Innovation Award, 2007 Santa Clara Global Social Benefit Incubator
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