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View the documentActivity no. 1 - The hen that laid golden eggs
View the documentActivity no. 2 - Phrases that should never be said
View the documentActivity no. 3 - Caring for our environment: a necessity for now and the future
View the documentActivity no. 4 - Building a solar heater/cooker

Activity no. 4 - Building a solar heater/cooker


Building a solar heater/cooker

A participatory activity designed to construct a practical solar heater/cooker and at the same time increase group understanding of the difference between renewable and non-renewable resources.

HOW?


How?

· The group leader starts off a discussion about how our natural resources are of three kinds:

Renewable (that is, they can be managed so that they are constantly replenished) such as forests, water and agricultural land

Non-renewable (that is, when they are used up, they are gone for ever) such as oil, coal and natural gas

Unlimited such as the wind and sun

· The group then constructs a practical solar heater/cooker to demonstrate how solar energy can be used.

· If possible, the solar heater/cooker is maintained and used to produce some saleable commodity as an income-generating activity for the group.

FOR WHAT? / WHY?

So that group members will be able to:

· Understand the difference between renewable and non-renewable resources.

· Make rational decisions about the need to limit dependence on non-renewable resources and manage renewable resources.

· Gain practical experience in using the sun as an alternative energy source.

WITH WHAT?


WITH WHAT?

· The plans for building a simple solar cooker on pages 43-45.

· Locally-available, inexpensive materials (two cardboard boxes, one roll of aluminum foil, one piece of glass 30 x 50 cm).

· Group participation.

Some background information for the group leader

What are renewable and non-renewable resources

Some of the resources on the Earth are present in limited quantities and when they are used up, they are gone forever. These resources are called :nonrenewable. Examples of non-renewable resources are coal, oil, natural gas and other fossil fuels; silver, gold, diamonds and other metals and minerals.

Since we cannot create more of non-renewable resources, the only way we can protect these resources is to use them as efficiently and carefully as possible. At the same time, it is necessary to plan to satisfy our needs using other resources. Rut no matter how careful we are, if the number of people continues to increase rapidly, the demand for these non-renewable products will also increase, and there is the chance that many of them will be used up before we can develop alternatives.

Other natural resources, if managed properly, can be used over and over again without ever running out. These are called renewable resources. Some examples of renewable resources are agricultural land, pastures, forests, water and all of the living things which we use to sustain ourselves (plants, animals, fish, etc.). People are also a renewable resource. To continue to provide for us and for future generations, renewable resources must be carefully protected and managed. Otherwise, they too can be consumed and lost forever.

Unfortunately, this destruction of renewable natural resources is already a serious problem in many areas. In Africa, many species of animals have disappeared completely. Others exist only in very small numbers in game parks or reserves - such as lions, elephants and giraffes.


The cow

Even more serious is the destruction of land and water resources. Under pressure from rapidly increasing populations, the forests and grasslands of Africa are being cleared for agricultural production at a rapid pace. Much of this land, however, is unsuitable for sustained agricultural production and when its protective cover of grass and trees is removed, erosion quickly sets in. Once the thin layer of fertile topsoil is washed or blown away, the land will never again be able to support life. Barren stretches of what was once green pasture can be seen all over Africa.

The cutting of the wooded areas is also having a damaging effect on the supply of water - already in short supply in much of Africa. When the living cover is removed from the soil, it loses its ability to hold water and release it gradually. As a result, when there is no rain, the soil is dry and arid. Then when the rains come, without the protective cover of grass and trees, the water rushes along the soil without seeping in, causing floods and damage to crops and livestock, and loss of human life.

It is not too late to save our renewable resources. But each one of us must do our part to conserve and protect them. It is not a job that we can delegate to others or expect the government to do for us.

There are also a very few resources which. at least for the moment, seem to be available in unlimited quantities. Two of these are wind and sun. In many areas, people are beginning to develop ways to use the sun and wind to meet our energy needs.

The solar cooker which the group will build as a part of this activity can be used to cook most of the foods which we normally eat, without using any of the fuels we usually require (oil, kerosene, wood, etc.).


The sun

Not only does this help us to conserve non-renewable and renewable resources, but it also can save time and money. Although the solar cooker takes a little longer to cook food than a traditional stove or fire, no time is required for collection of fuelwood. or the purchase of fuel. And since the solar cooker maintains an even temperature, it is not necessary for someone to constantly watch the food that is being prepared. While the solar cooker is working, the person responsible for preparing the meal can be doing other activities.

Building a solar cooker


Materials require for building a solar cooker

Materials required:

· Two cardboard boxes, one slightly smaller than the other. The larger box should have a top or lid.

· One roll of aluminum foil.

· One piece of glass approximately 30 x 50 cm.

· Some dry grass, straw or sand.

The building process:


The building process:

1) First, as in the drawing, take the smaller cardboard box and cover all the inside surfaces except the bottom with aluminum foil. Also cover the inside of the lid or cover of the larger box with aluminum foil.

2) Cover the bottom of the inside of the smaller box with some dark coloured material (painting it black would be best, but even colouring it with dark-coloured soil would be O.K.).

3) Take the larger cardboard box and put a layer of straw, dry grass or sand in the bottom.

4) Now place the smaller box inside the larger one and fill up the space between the two boxes with more sand, straw or dry grass. This material will help to keep the heat in your solar cooker. Cover the filled space between the two boxes with something that will keep the sand or grass from getting inside the smaller box (perhaps another strip of cardboard box).

5) Place the piece of glass over the top of the cooker so that it completely covers the smaller box, and the solar cooker is done.

6) To use the solar cooker, remove the piece of glass and place the food to be cooked (in a dark-coloured pot) inside the cooker. Then replace the glass.

7) Put the solar cooker in a sunny place and position the lid of the outside box so that it reflects the rays of the sun into the box (as in the diagram). In not much more time than it usually takes to cook whatever food it is, your solar cooked meal will be ready.


Solar cooker in a sunny place

Booklets in this Leaders Guide Series:

Introduction
Population and Agriculture
Population, Employment and Income
Population and the Environment
Population and Nutrition
Population and Health
The Family and Family Size
Human Growth and Development
Responsible Parenthood
How the Population Changes
Community Involvement

Food and Agriculture Organization of the United Nations


Integration of Population Education into Programmes for Rural Youth INT/88/P9