Make a Pot in a Pot Refrigerator

In a community or situation without electricity, storage of food long-term can be tricky. One simple solution is to build your own pot-in-pot fridge, using basic pots, sand and water. An idea revived by Mohammed Bah Abba, this refrigerator is now being used by many farmers in warm climates who need to preserve their food for a longer time and keep the insects away.

Keeping the sand moist all the time enables evaporation to cool the produce kept inside the inner pot. This enables the storage of freshly grown vegetables to last much longer than usual in a hot climate. It is also great for using at a picnic or outdoor meal where there is no electricity outside but food or drinks need to be kept cool. Here is how to make your own.

Steps

  1. Obtain two large clay or terracotta pots. One pot must be smaller than the other pot. Check that the smaller pot fits inside the larger and that there is a space around it of at least one centimetre, up to three centimetres.
  2. Fill in any holes at the base of the pots. Use clay, large pebbles, cork, a homemade paste - anything suitable to hand to fill the hole. If you leave the holes open, the water will enter the inner pot and will also run out of the larger pot, making the fridge ineffective.
    • Putty or duct tape can plug the hole.
  3. Fill the base of the larger pot with coarse sand. Fill about 2.5cm/1 inch deep, and only fill to a height that will ensure the smaller pot sits even in height with the larger pot.
  4. Place the small clay pot into the large pot. Arrange its base flat on top of the lower layer of sand.
  5. Fill all around the small pot with sand. Fill it almost all the way, except for leaving a small gap at the top.
  6. Pour cold water over the sand. Do this until the sand is completely soaked and unable to take any more water. As you pour, do so gradually in order to give the water time to soak into the terracotta.
  7. Take a cloth, tea towel or towel and dip it into water. Place it over the top of the inner pot so that it covers it completely.
    • Wet hessian or similar fabric also works well.
  8. Allow the inner pot to cool down. If you have a thermometer, you can use this, otherwise test the temperature with your hands.
  9. Keep the pot-in-pot refrigerator in a dry, ventilated space for the water to evaporate effectively towards the outside.[1]
  10. Place vegetables or other items inside for storage. You will need to keep checking regularly for the dampness of the sand. Pour in more water as it becomes drier to keep it well moistened. Usually this will need to be done twice a day.[2]
    • You can add food or drinks to the pot-in-pot refrigerator if you're having an outdoor party or picnic. Make one for the drinks and one for the food if you have a lot of items.

Tips

  • The pot-in-pot refrigerator is also known by its Arabic term, a "Zeer" pot.
  • [[Image:Drinks in pot.png|200px|thumb|
  • Try different types of vegetables and fruit to see how long they last using the pot. Natural Innovation notes that "Abba's project has brought about major changes for many Nigerians: eggplants can last for 27 days rather than three, African spinach can be kept for 12 days instead of spoiling after one day, while tomatoes and peppers stay fresh for three weeks. Food hygiene standards and overall health are improving."
  • Meat can be kept for up to two weeks, as opposed to a few hours without this device. [3]
  • If selling the produce, place some of the produce for sale atop the damp cloth that is sitting over the middle pot. This will keep the exposed produce a little cooler, as well as letting people know what you have for sale.
  • Water and other liquids can be kept at 15ºC.[4]
  • It is also possible to store sorghum and millet grains this way - the pot-in-pot refrigerator protects against humidity and stops fungi growth.

Warnings

  • Do not use glazed earthenware; only unglazed.
  • Evaporative cooling works most effectively in dry heat and this pot-in-pot refrigerator is no different. In high humidity, you will find that this solution does not work.

Things You'll Need

  • Two clay (terracotta) pots, unglazed, one larger than the other
  • Sand
  • Water
  • Cloth to cover the pots
  • Clay, cork or other material to plug holes in the pots if they have them

Related Articles

Sources and Citations

  1. ↑ Wikipedia, Pot-in-Pot Refrigerator, http://en.wikipedia.org/wiki/Pot-in-pot_refrigerator
  2. ↑ SciDevNet, Refrigeration, the African Way
  3. ↑ Slashfood, How Cool is That Zeer Pot?, http://www.slashfood.com/2006/09/28/how-cool-is-that-zeer-pot/
  4. ↑ SciDevNet, Refrigeration, the African Way, http://www.scidev.net/features/index.cfm?fuseaction=printarticle&itemid=315&language=1
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