This clay pot cooler is being marketed as Mexico’s “first 100-percent ecological clay refrigerator” by its manufacturers Depresa.
The device, called Ecoplanet, uses no electricity and maintains a temperature of around five degrees Centigrade. It works by using a porous outer layer lined with wet sand, and an inner pot within which the food is placed. The evaporation of the outer liquid draws heat from the inner pot. See exoplanet.mx for more details.