Heat-retention cooking

From Solar Cooking

Heat-retention cooking (or retained-heat cooking) saves cooking fuel because after food has been heated to cooking temperature, it is placed into an insulated box where it will continue to cook until it is done. Retained-heat cooking is often introduced along with solar cooking since it further reduces the use of traditional fuels such as firewood, and the use of this method allows much more food to be cooked each day in a solar cooker. This method of cooking is also known as fireless cooking, haybox cooking, or wonder box cooking.

1 Using a solar box cooker as a retained-heat cooker
2 News and recent developments
3 See also
4 External links

[edit] Using a solar box cooker as a retained-heat cooker

Rice being cooked in a heat-retention cooker

When combining retained heat and solar cooking, if food has gotten thoroughly hot in an solar box cooker (SBC), but clouds arrive before the food is finished cooking, a switch from solar to retained heat cooking should be made before the oven temperature drops below the boiling point. For large recipes this may be accomplished by simply closing the reflective lid on the pots of cooking foods. For smaller recipes, the solar oven is opened, taking care not to allow steam to escape from under the lids, pots are pushed close together along with any heated additional mass. Insulating pads or soft cushions are tucked closely around the pots and well heated mass. The SBC lid is then closed. This effectively makes the transition from solar to retained heat cooking. The cooker lid remains closed until shortly before serving time, when the food is tested. If not completely done, a very little conventional fuel will usually finish the job.

Usually solar/retained heat cooking is done right where the SBC is located. However, a lightweight portable SBC can be moved temporarily indoors for its retained heat cooking time if the sun clouds over or if it rains. It may also be brought inside more or less permanently during the off season or at night and function as an insulated box for retained heat cooking. Used in this way the SBC continues to save fuel rather than simply being stored until conditions are right for solar cooking.

[edit] News and recent developments

November 2007: At the 2006 International Solar Cookers Conference in Spain, Wietske Jongbloed of the KoZon Foundation learned a useful trick from David and Ruth Whitfield: a heat-retention cooker can be made from empty rice bags. The Whitfields advised that two large rice bags, with insulation such as wool or cotton in between, make a sack that will keep a pot of food at cooking temperatures long after it is removed from a heat source. KoZon introduced the idea in Tahoua, Niger, where cooking pots are typically very large — 12 to 16 liters. For these pots, four rice bags are needed to surround the pot, and a fifth bag stuffed with insulation covers the top. Of this five-bag system, Jongbloed says, “It is named ‘Idadafoua’ and works marvelously.” Jongbloed writes that women in the Sahel cook meals for families of 10 to 12 or more people. The KoZon project in Tahoua teaches the use of three cooking devices — fuel-efficient wood stoves, heat-retention cookers, and solar CooKits. CooKits are used on sunny days for meat or fish sauces, eggs, sweet potatoes, and groundnuts, and for cakes that are sold by the slice to earn money.