In some parts of the world, people spend more money on fuel to cook food than they spend on food itself (see References 1). Solar stoves and ovens can put an end to that practice, because they require no fuel to operate, using passive solar energy to heat food and water. You can use solar cookers, too, and even make them yourself at home.
Solar cookers must be able to turn the sun's energy into heat and then trap and retain that heat to create temperatures high enough to cook food. The easiest way to do this is to use a black or dark-colored container, which heats up when exposed to sunlight. Surround the container with a transparent box or envelope, which allows light to enter but stops heat from leaving, and you have a simple solar oven. Cheap solar ovens can reach 250 F, while models that are more expensive may heat up to 350 F (see References 1).
Countless solar oven and stove designs exist, but they all fall into a few basic categories. Box cookers are the best-known type of solar oven, consisting of a box with a transparent cover and a flap covered in reflective material that directs sunlight into the box. Panel cookers have several reflectors, directing light onto a heat chamber enclosed in clear plastic or glass. Parabolic cookers have a round or satellite-shaped reflector, with a heat chamber mounted above the reflector's surface so users can direct light onto it from several directions. (See References 2)
The primary application for solar cookers is in undeveloped and rural areas with little access to fuel and electricity. For example, the U.S. Department of State reports that solar ovens may stop deforestation in Uganda by giving villagers an alternative to cutting down trees for fuel (see References 4). Solar ovens are useful for sterilizing medical instruments, helping doctors maintain sanitary operations even in remote field offices (see References 5).
Researchers and nongovernmental organizations are hard at work developing solar cookers that can safely heat food and water without becoming dangerous or unwieldy to the people who need to use them. Although solar stovetops are rare, one research group at the University of Arizona developed a solar collector that sits outside a home, collecting energy and converting it to heat a flat cookplate (see References 6). This type of technological advance can make it possible for restaurants and larger facilities to cook for groups of people using only the power of the sun.
- NASA Earth Observatory: Baking in the Sun
- Solar Cookers International: Build a Solar Cooker
- U.S. Department of State: Will Cooking With Solar Ovens Stop Deforestation in Uganda?; January 2010
- "Journal of Applied Microbiology"; Sterilization of Instruments in Solar Ovens; A. F. Jorgensen, et al.; 2002
- U.S. Environmental Protection Agency: User-Friendly Solar Ovens for Outdoor and Indoor Use
- Michael Smith/Getty Images News/Getty Images