Wikipedia
Wonderbag is a stand alone, non-electric insulated bag designed to reduce the amount of fuel required in the cooking of food in developing countries. Instead of being placed on a stove for the duration of the cooking period, food is instead heated to a hot enough temperature then transferred to the Wonderbag, which uses the principle of thermal insulation to continue cooking, and keeps food warm without needing addition fire, or additional heat. Working on the principle of thermal cooking, the Wonderbag is estimated to save up to 30% of the total fuel costs associated with cooking with Kerosene ("paraffin") alone. In developing countries there are numerous advantages for the product, as it immediately helps ease deforestation of natural reserves, and it frees up those who would spend their time gathering the extra wood for fire fuel.
Designed by Durban, South Africa-based entrepreneur Sarah Collins of Natural Balance, and poverty activist Moshy Mathe, the Wonderbag is aimed at societies where fuel is expensive or time-consuming to gather.
As of January 2012, over 150,000 Wonderbags were in use in South Africa, with the manufacturers and partners such as Unilever intending to promote the use of the device worldwide. over 650,000 have been distributed in "South Africa, Rwanda, Kenya, and Syrian refugee camps in Jordan."