Free Energy from Sun Helps Cooks Make Savings
Help the Planet by Cooking with Renewable Energy
Jul 1, 2008
It is easy and cheap to make solar ovens using basic materials. They are low-tech, and are powered by a source of heat that is free, non polluting, and clean - the sun.
Solar cooking is especially useful in places where there are regular and predictable hours of sunshine. These are often the dryest parts of the world where wood and other fuels are hard to come by.
Solar cookers are already being used by those on expeditions as an alternative to calor gas portable cookers or camp fires. In these days of spiralling fuel prices, perhaps there is a place in the developed world for the solar cooker.
How Solar Cooking Works
The underlying principle of solar cooking is to trap sunlight and retain it through insulation. Mirrors or foil covered boards are used to reflect the sun’s rays towards the cooking pot, which is enclosed in either a box with a clear lid or in a polythene bag. Cooking pots used in solar cooking ideally have black, tight fitting lids in order to absorb and retain the maximum heat.
Three Solar Cooker Designs
There are three main designs; the most popular one is an insulated box with a glass or plastic lid that lets the sunlight through and keeps the warmth in.
The parabolic design uses a highly polished reflecting dish to focus the sun’s rays onto the cooking pot. These can get extremely hot and need monitoring constantly.
The third type is a panel cooker that reflects light and concentrates it on a cooking pot. The panel type is the cheapest to manufacture and because they are light and inexpensive have been used by the poorest communities in India, Africa and China to great advantage.
Smoke Free Cooking with Solar Cookers
Many people have traditionally relied upon wood fires for their daily cooking. Anyone who has cooked over a barbeque will know how painful it is if smoke gets in the eyes. For women in Africa this has been a constant problem that is being solved by solar cooking. Another advantage is that solar cooking saves them hours of valuable time that they previously spent searching for wood.
Food Pasteurisation with Solar Cookers
Harmful food microbes, including bacteria and viruses, are killed when heated to 65ºC (150ºF). This is called pasteurization. Food cooks at 82 - 91ºC (180 - 195ºF).
Simple solar cookers cook can easily achieve such temperatures and have the advantage that they also maintain moisture and nutrients, and rarely burn or overcook. Parabolic solar cookers can cook at temperatures much higher than this.
Water Pasteurisation with Solar Cookers
Worldwide, unsafe water is a major health problem. Preventable water-borne diseases are responsible for approximately 80% of all illnesses and deaths in the developing world. Two million children die each year from such diseases.
These deaths are preventable through solar pasteurisation of polluted water. Solar Cookers International is a charity that promotes the use of solar cookers in the developing world where such illnesses are rife.
How is Pasteurization Achieved?
Simple solar cookers can pasteurize water for a family at a rate of about one liter per hour. The solar cooker’s built in thermometer is used to check that the water has achieved pasteurisation temperature and is therefore safe to drink.
References
Solar Cookers Review, Solar Cookers International, 1919 21st Street, #101 Sacramento, CA 95811, U.S.A. T: +1 (916) 455-4499
 |
 |
 |
 |
