Correlation to State Science Standards:
Grade 9-12 Physical Science #3
Biology #6
Earth Science #4
Investigation and Experimentation #1

Correlation to State Social Studies Standards:
Grade 10-12 #10.13
#11.10
#12.14

Promoting Sustainable Living Through Inspirational Environmental Education

The following learning unit is suitable as a monthly project for Earth Teams. It is brought to you as an educational program of the Institute for Solar Living (ISL), a nonprofit environmental education organization. To learn more about ISL programs, including field trips to the Solar Living Center, a sustainable living demonstration center in Hopland, California, please contact:

Institute for Solar Living
P.O. Box 836
Hopland, CA 95449
Phone: (707) 744 2107
Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
Web site: www.solarliving.org

Much of the information and both sets of plans in this unit came from Solar Cookers International, a nonprofit organization that is "spreading solar cooking to benefit people and environments worldwide." For more information about SCI, solar cooking, and how to get involved with this hard working and effective organization, phone (916) 455-4499, email This e-mail address is being protected from spam bots, you need JavaScript enabled to view it or go to www.solarcooking.org

Introduction

In the following learning unit, you will learn what solar cookers are, who is using them around the world, and why they are good for people and the environment. You will then have the opportunity to build one or more different types of cookers to try for yourself using plans included in this unit. By trying them out, you can gain a personal understanding of how they work. If you build more than one, you can compare construction, cost, effectiveness and ease of use.

The learning in this unit can be related to a variety of subjects such as physics, biology, geography and environmental studies.

Contents

1. What is solar cooking?
2. Why use solar cooking?
3. Who is using solar cooking?
4. How do solar cookers work?
5. Types of solar cookers
6. How to build a solar folding box cooker.
7. How to build a solar box cooker.
8. How to build an optional high-performance "stove top" or frying cooker.
9. Experiments with solar cookers.
10. References.

1. What is solar cooking?

Solar cooking uses the sun as a direct energy source for cooking food or pasteurizing water. There are many types of solar cooker designs. Some are very simple and are suitable for slowly cooking food over the course of several hours. Others are more complex and can boil water or fry foods in less than an hour. In most designs, solar energy strikes reflective surface that directs sunlight onto a dark colored cooking pot which absorbs the heat and cooks the food. In some cases the heat is held around the pot by a transparent material such as glass, hard plastic or even a plastic bag.

Solar cooking is a simple and inexpensive technology. The simplest cookers can be built in just a couple of hours and cost only a few dollars.

Learn more! Optional study questions:
What is the solar resource? How much solar energy is available:

• In heat energy units?
• In electrical energy units?
• At your location?
• In other parts of the world?
• Can you make some guesses on where in the world there is enough solar energy available for solar cooking?

2. Why use solar cooking?

There are many good reasons for using solar cookers that can be divided into the categories of health, economics, social and environmental.

Environmental reasons for using solar cooking:

• Solar cooking can reduce the amount of wood, charcoal and dung burned for cooking and heating. Throughout the world, two and a half billion people (nearly half the Earth's human population) spend a large part of their time or income gathering wood. If each of these people used 2 pounds of wood per day, the total would be 5 billion pounds of wood that are burned every day. This tremendous use of wood contributes to two serious environmental problems:
• Deforestation. 
    In many parts of the world, such as in parts of Africa and Asia, populations are using wood at a much faster rate than it is growing back, with the result that the total amount of forested land is shrinking rapidly. As forests disappear or recede, the ecosystems that are dependent upon the trees also recede or disappear. As ecosystems disappear, we risk the loss of biodiversity. In addition, in some places such as around the edges of the Sahara desert in Africa, the loss of trees and shrubs to hold fertile soil in place is allowing desert sands to encroach upon areas that were once productive for raising crops or livestock. The loss of this land is devastating to a continent that struggles to feed itself. Another effect of deforestation is that it reduces the Earth's natural ability to regulate the amounts of carbon dioxide and oxygen in the air. Trees and other plant life take carbon dioxide from the air and produce oxygen. As deforestation accelerates, there are less trees to use the growing amount of carbon dioxide (CO2) in our atmosphere- a condition that contributes to global warming.
• Global warming.  
  The above-normal heating of the Earth's atmosphere is caused by a greenhouse effect where carbon dioxide and other gasses emitted from the burning of fossil fuels trap heat in the atmosphere and cause a rise in Earth temperatures. Global warming is thought to cause erratic weather patterns with more storms. If global warming is allowed to continue, it will cause an accelerated melting of polar ice caps capable of raising sea levels to the point of flooding many coastal cities around the world. Whole island nations, as some in Micronesia that are now just barely above sea level, may even completely disappear. The burning of wood, charcoal or dung releases large amounts of carbon dioxide that contributes to global warming. The use of solar cookers does not release gases causing the greenhouse effect.

Learn more! Optional study questions:

• The amount of wood burned for cooking each day around the globe numbers in the billions of pounds. In comparison, how many pounds of lumber are harvested in the U.S. each day? Each year?
• Besides wood burning, what are other major sources of carbon dioxide and other greenhouse gases?
• Besides solar cooking, what other uses of renewable energy can be used to help prevent global warming?