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Primitive ideas of ancient peoples by today’s means were not that primitive after all. For instance these ideas allowed for desert people to have ice during summer when there was no ice for thousands of kilometers around. Yakhchal is one such idea.
People needed to keep perishable food on low temperatures before the refrigerator appeared as well as today. As a source of cold in the wormer months they used ice from lakes and rivers stored in ice houses during the winter. Read more about history of ice houses.
Refrigeration is one of the main food storage techniques in developed countries. But it was not always so. To keep our food cool we had to harvest ice from the nature itself. Today almost every household has a refrigerator. Read about refrigerator history.
Although it looks like a new invention idea of a solar-powered refrigerator is relatively old and pretty simple - to use heat of the sun instead of the compressor in the refrigerator to liquefy the refrigerant. Read more about solar-powered refrigerators.