Hesperian Health Guides
Fuels for Cooking and Heating
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Wood, crop wastes, coal, dung, and charcoal are the most widely used cooking fuels. But when they burn, they can all cause pollution and breathing problems. And in many places, wood and charcoal are scarce resources.
Many people are turning to other cooking fuels such as sunlight, processed plant wastes (rice husks and other crop wastes made into pellets or briquettes), and biogas (a gas produced by rotting plant matter and human and animal waste).
|Mixing chopped crop wastes with water, and pressing and drying them, makes a cleaner burning fuel.|
Crop wastes (residues)
Dried crop wastes, such as rice and maize husks and coconut shells are used as fuel in many places. When these materials are used without processing, they cause smoke that can lead to health problems.Chopping the material and pressing it into blocks (fuel briquettes) can make it burn longer and cleaner.
|Stacking wood in the house helps it dry and burn with less smoke.|
Making fuel briquettes requires some machinery and an energy source, both of which can be costly. Some people do not like the taste of food cooked with briquettes. But in areas where there is a shortage of fuel, or where people want to limit the use of coal and charcoal, briquettes may be a good choice.
Wood is one of the best sources of fuel, but it is scarce in many places. To conserve valuable forest resources and reduce smoke, use dry wood, cut into small pieces.
Biogas, a natural gas that is mostly methane, is a valuable source of energy. By turning the organic matter in human, animal, and plant waste into energy, biogas turns waste products into a resource less harmful to the environment and community health than other fuels. (To learn more about biogas, see Other Environmental Health Resources.)
Cooking with sunlight
You can use the sun’s heat to cook in solar cookers. Solar cookers require changing your regular cooking habits, and many solar cookers cook more slowly than a fire or a stove. But by using the solar cooker when the sun shines brightly, and using the regular household stove at night or when the weather is cloudy, you can save fuel. Some cookers can pay for themselves in just a few months because they reduce expenses for charcoal, gas, or firewood. Solar cookers can also be used to disinfect water for drinking.
Guidelines for cooking with sunlight
There are many kinds of solar cookers you can make or buy (see Other Environmental Health Resources). All of them work in basically the same way. They:
- change sunlight to heat energy. Dark surfaces get hot in sunlight. Food cooks best in dark, shallow, thin metal pots with tight-fitting lids to hold in heat and moisture.
- retain heat. A clear heat trap around the dark pot lets in sunlight and traps heat. Use a glass top, an upside-down glass bowl, or a clear, heat-resistant plastic bag marked HDPE.
- capture extra sunlight. Shiny surfaces reflect extra sunlight onto the pot to help cook food faster. Aluminum foil mounted on cardboard provides a good, low-cost shiny surface. Sheet metals and metallic paints are not reflective enough to work well.
When building a solar cooker, do not use materials that will melt or give off fumes, such as styrofoam, polyvinyl, or some plastics.
How to use a solar cooker
Use a black pot with either a black or clear glass top. To help it cook faster, cut food into small pieces and add a small amount of water. Place a blanket or other insulation under the oven and place the oven in full sun just before and during the hottest part of the day. Be sure that the solar collector opening faces toward the sun. Turn the oven every 30 minutes or so to face directly into the sun. If the sun goes behind a cloud, surround the oven with more insulation. If the the food is hot but not cooked, finish cooking the food on a stove or fire.
|Faster cooking||Slower cooking||No cooking|