Here’s a great example of what E F Schumacher called ‘intermediate technology’, an innovation that improves on traditional methods without requiring all the infrastructure of the the developed world.
The ‘zeer pot’ consists of two clay pots, one inside the other, with a layer of sand in-between. It is placed on a stand, water is poured into the sand, and covered with a damp cloth. In the heat, the water evaporates outwards, drawing heat from the inside pot and cooling the contents.
Other than topping it up with water a couple of times a day, it requires no energy, and can be made from locally available natural materials. Vegetables, sorghum, water or medicines can then be preserved for longer.
Variations of the design, all based on the same principles of evaporation, are found all round the world and have been found by archeologists. That didn’t stop the Daily Mail from running the headline ‘Amazing solar-powered fridge invented by British student in a potting shed helps poverty-stricken Africans‘ earlier this year, after a student made a metal version of the same thing.
Practical Action are a charity that specialise in this form of development, developing and promoting small devices and techniques that can be shared cheaply, but that make a big difference. They are currently teaching people about the zeer pot in Sudan.