Hay bag cooker is an energy-saving cooking device. It saves fuel from 25% to 50%, depending on the cooking medium - whether charcoal or biogas. Materials The hay bag cooker is filled on all sides with 3-5 inches thick layer of any of the following insulating materials: Hay Feather Raw Cotton Old woolens Fibre glass Old newspaper shredding The bag can be stitched out of cotton, plastic or leather. Process Cook the food till it achieves the boiling point. After boiling it for five minutes, pick up the cooking vessel from the fire and put it inside the hay bag. The well-insulated walls of the haybag retain the heat and assist in completion of the cooking process. It generally takes no more than half an hour for cooking the food in the hay box. However, it is advised that the bag should not be opened for at least one hour for a tasty outcome. In order to attain optimum results, hard pulses, and food grains like pigeon peas should be broken into small pieces and soaked for about 4 hours prior to cooking. Advantages The hay bag is portable and could be carried easily on a bicycle. The cooked food, inside the hay bag, remains hot for about 4 or 5 hours. Source : Centre of Science for Villages, Magan Sangrahalaya, Wardha, Maharashtra