Solar cookers slowly replacing use of wood

Jan 01, 2006

THE new millennium is confronted with world hunger, contaminated water, deforestation and the fuelwood crisis. The invention of simple, inexpensive and low-tech solar cookers has resulted in the emergence of solar cooking as a solution to the problems.

By Betty Kituyi

THE new millennium is confronted with world hunger, contaminated water, deforestation and the fuelwood crisis. The invention of simple, inexpensive and low-tech solar cookers has resulted in the emergence of solar cooking as a solution to the problems.

An early European record of cooking in a solar box was made by Horace de Saussure, a Swiss naturalist experimenting as early as 1767.

Saussure reported successfully cooking fruits with initial temperatures of 189.5 F (87.5 C).
In Africa, the tradition of firewood cooking is slowly being replaced by solar cooking.

In Kenya, Nigeria and Eritrea, testimonies on the wonders of the solar cooker as reported in the Solar Cooker Internal Review Magazine are already coming up.

Dr Mercy Bannerman of Ghana reported a reduction in diarrhoea and guinea worm cases in communities that use cookers to boil their drinking water.
Mary Frank, an American artist, is fanatic about solar cooking. She demonstrates how to use the solar cooker in cooking fruit dishes, rice and even lamb whenever she exhibits her art.

In Uganda, disabled technicians told the Solar Cooker International Review Magazine last April that they had produced over 100 solar cookers. In all these places, the solar cooker has been used in transforming livelihoods by boiling water and cooking food without using a matchbox, charcoal or firewood.

People using solar cookers say they save time because they don’t need to keep checking on the food. Therefore, they can spend more time with their children and also engage in income-generating activities like sowing and making some baskets. They testify of no sore eyes and coughs.

According to a document entitled, Principles of Solar Box Cooker Design, solar cookers are heated up when rays of the sun enter the solar box through the glass or plastic top. The light is turned into heat energy when absorbed by the cooking pots. The heat input causes the temperature inside the cooker to rise until the heat loss of the cooker is equal to the heat gain.

Because it is of a longer wavelength, most of the radiant energy cannot pass back through the glass or plastic and is, therefore, trapped within the enclosed space.

Barbara Prosser Kerr, a solar cooker advocate, says with simple materials such as cardboard, aluminum foil and glass, one can build an effective solar cooking device. Other materials include wood, plywood, bamboo, metal, cement and bricks. Others are stone, fiberglass, rattan, plastic, clay and tree bark.

Experts recommend good insulation of the solar cooker to prevent heat loss with aluminum foil, feathers, spun fiberglass, rock wool, cellulose, rice hulls, wool, straw and crumpled newspapers. Most of these are fairly inexpensive.

Cooking consists of putting the food in a dark, lidded pot and pointing the cooker at the sun. Sunlight reflects off the foil and goes to the pot. The light is then absorbed and converted into heat, which cooks the food in the pot.

There are three models of solar cookers; box cookers, panel cookers (which look like reflectors put in car windshields) and parabolic cookers (a large reflective dish with a pot in the centre). Solar cookers can reach up to 300 degrees Fahrenheit or higher.

I have an experience of homemade solar cooking in my backyard at my urban home. I was amazed with the basic nature of the solar cooker, which involves folded cardboard flaps lined with a shiny material. Such a low cost equipment.

A friend recommended that I cook rice and water starting at noon when the sun is bright and high in the sky and that I use a black cooking pot. It takes me one hour to cook one mug of rice. I also boil water and sometimes bake cakes with it, thus saving on the fuel costs.

Many of our mothers still cook over fires. It is tedious and hazardous to gather wood and cooking over smoky fires. This is an invisible problem yet firewood is a non renewable energy source that has led to deforestation and desertification in our country. The solar cooker might be the saviour in our situation.

In this country, the use of solar cookers could save millions of tonnes of firewood per year and reduce on emissions of carbondioxide while improving the climate, health and relieving burdens caused by fuel shortages.

For upcoming workshops on the solar cooker, call 077603880
kituyibettyk@yahoo.co.uk

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