21-year-old student Emily Cummins has created a portable solar-powered fridge specifically for use in developing countries. The revolutionary design needs no electricity, and can be made from commonly available materials like recycled metal, cardboard and sand.
Emily Cummins' solar-powered fridge works on the principle of evaporation by using both convection and conduction. The goods to be refrigerated are sealed in an interior metal chamber. Sand, wool or soil is placed between that inner chamber and the outer chamber, and as it is warmed by the sun, water evaporates and thereby cools the fridge's inner chamber. It can maintain a temperature of 43 degrees Fahrenheit for several days.
Cummins' solar-powered refrigerator has been implemented in South Africa, Zambia and Namibia.