Mohammed Bah Abba made a really cool invention, which won a Rolex Award of $100,000 –a refrigerator than runs without electricity. Here’s how it works. You take a smaller pot and put it inside a larger pot. Fill the space in between them with wet sand, and cover the top with a wet cloth. When the water evaporates, it pulls the heat out with it, making the inside cold. It’s a natural, cheap, easy-to-make refrigerator.
Evaporative fridges are a relatively well-tested, proven, low-tech approach to cooling. They can cool products, food and beverages at about 15-20 C below ambient temperatures. They are most appropriate in hot, dry (not humid) climates (Source)
there are some other fun DIY items to see -
In response to scarcity of electricity in Northern Nigeria, one man created a device similar to a refrigerator using two pots. Here’s how it works: You take a smaller pot and put it inside a larger pot. Fill the space in between them with wet sand, and cover the top with a wet cloth. As the water evaporates from the sand, it pulls the heat out with it, cooling the inner pot. It’s a natural, cheap, easy-to-make refrigerator. The invention keeps food from perishing for up to three weeks.
This simple invention doesn’t require electricity, which is better for the health of the environment compared to traditional methods of burning dirty coal to generate electricity. In addition, this device acts to solve societal problems associated with scarcity of electricity. Furthermore, the device is rather simple and seems plausible even for the world’s most impoverished.
from The Future We Want