The pot-in-pot refrigerator (also known as the zeer) was invented in 1995 by Nigerian teacher Mohammed Bah Abba. Its inspiration came from a growing need to keep food fresh longer in the small communities of third-world countries that have little to no electricity.
The design of the pot-in-pot refrigerator is a very simple one. In fact, you can build one at home! Here are some instructions:
- First, find a large earthenware pot; clay, not plastic. Pour a layer of sand at the bottom.
- Then place a smaller pot (approximately 1-2 inches less in diameter) inside of the larger pot, making sure that there is enough sand at the bottom so that the tops of the two pots are even.
- Fill the space between the two pots with sand.
- Pour water into the sand until itâ€™s completely saturated.
- Place the food you wish to keep cool inside of the smaller pot and cover it with a damp cloth.
- Refill the sand with water at least twice a day and check the cloth regularly to make sure that itâ€™s damp.
As the water evaporates from the sand, it absorbs the heat from inside of the smaller pot and carries it away. This is how the zeer functions as a small-scale refrigeration device. According to Science in Africa magazine, the zeer can keep vegetables such as tomatoes fresh for up to 20 days and meat can survive well for about a week. It wonâ€™t replace your kitchenâ€™s refrigerator by any means, but itâ€™s a fun experiment!