Solar energy cookers catch on

By Fredrick Obura

The current dry spell has been more severe in recent months leading to hunger in many parts of the country.

The climate system is basically driven by energy from the sun. Experts argue that if the sun’s energy output were to change, so would the climate.

However, the main debate now in the public domain is how to harness solar heat into a worthwhile venture and channel the money meant for fuel into self- enhancement.

Solar Cookers International (SCI), a non-profit organisation has come up with a new skill to help in tapping the natural solar energy for domestic purposes like cooking and water purification.

Statistics indicate that nearly 25 per cent daily income of urban folks is spent on fuel. This money could be channeled into more pressing needs like education, medicine, housing or other investments if this new technology were to be embraced.

Most solar cookers work on basic principles. Sunlight is converted to heat energy that is retained for cooking. The cookers are portable, allowing one to cook at work sites or while pursuing outdoor activities like picnics, gardening or camping. The three most common types of solar cookers are heat-trap boxes, curved concentrators (parabolic) and panel cookers. Several large-scale solar cooking systems have been developed to meet the needs of various institutions worldwide.

High temperatures

Curved concentrator cookers, or "parabolic," cook fast at high temperatures, but require frequent adjustment and supervision for safe operation. They are useful for large-scale institutional cooking.

In separation from the normal cooking procedure, solar cooking is unattended, though it takes two to three times longer than any other conventional cooking. This affords one extra time useful for self-improvement and acquisition of new useful skills or even engaging in extra income generating activities.

Sunlight is the "fuel." A solar cooker needs an outdoor spot that is sunny for several hours and protected from strong wind, and where food will be safe. Solar cookers don’t work at night or on cloudy days. Food cooks best in dark, shallow, thin metal pots with dark, tight-fitting lids to hold in heat and moisture.

Since heat escapes each time the oven lead is opened, recipes that require high heat or lots of stirring should be avoided. A transparent heat trap around the dark pot lets in sunlight, but traps the heat. This is a clear, heat-resistant plastic bag or large inverted glass bowl (in panel cookers) or an insulated box with a glass or plastic window (in box cookers). Curved concentrator cookers don’t require a heat trap.

No burning

At moderate solar cooking temperatures food doesn’t need to be stirred and won’t burn. In the right circumstances it is possible to put a solar cooker out in the morning and return home in the late afternoon to a hot meal ready to eat.

Though solar cooking is possible in many of the Africa’s sub-Saharan countries, it is most practical for people living in climates that are generally dry and sunny for at least six months in a year.

In countries like Chile, small-scale vendors use solar oven to cook tasty stews, bread and other dishes.

The technology has helped the entrepreneurs of baked foods restaurants in saving money on cooking fuel and instead uses the money for expansion and self enrichment.

Major components of solar cooker are oven and a solar collector.

A typical solar cooker would require cardboard boxes, aluminum foil, double strength glass, black paint and a white paper glue.

Parabolic cooker for instance is made from reflective aluminum and a metal stand available in local supermarkets, it requires high temperature.

Cookit is made from aluminum foil, carton box, plywood, hard plastic, glue, a cloth binder and a polypropylene. The polypropylene is necessary for holding heat.

Locally the SCI partners with self help groups at divisional level who are concerned with energy conservation or other related activities to educate the entire community on the technology,

The groups also help in teaching the residents how to assemble the cooker.