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Cooking with the sun

 Liceulice - Serbia 24 October 2019

It may be unusual to many people but the Solar Oven is in fact a very simple and free method of cooking. It works by converting solar energy into thermal energy. So if you fancy saving on gas and electric bills give it a try, and learn how tens of thousands of people around the world have had their very own culinary revolution. (844 Words) - By Divna Vojinović


Liceulice Kuvanje na suncu

 Photo courtesy of Divna Vojinović/Liceulice

The Solar Oven is a simple device that takes a plentiful supply of energy, the sun, and converts it into heat. This heat is then used to cook foods temperatures lower than a conventional oven but more than high enough to cook food and sterilize water. It has been a revolution for people who live in areas that have a combination of chronic fuel and energy shortages as well as substantial risks of fires, such as the refugee camp in Darfur which has been issued with over 10,000 such devices.

There are more than 65 basic models of the solar oven which differ in design, materials and construction but they all have got the same basic characteristics:

Concentration of sunlight - by using mirrors and metals, which have a greater power of reflection, to focus the sunlight on a small area.

Converting sunlight to heat energy - dark surfaces (the floor of the oven) and cooking containers inside the oven will increase efficacy in collecting and absorption of sunlight.

Trapping heat - the isolation and retention of warm air is very important to the cooking process and it can be obtained by putting plastic wrap or glass panel over the box. The insulation of the solar oven is made from substances that are not a risk to health and stable under high temperatures.

Combining the above principles sunlight entering into the box is converted into heat and stays "captive" in the box. It is a simple technology using a simple power source and one that can be replicated easily.  Of all types of solar oven the easiest to construct is a "box-type", and if you want to give it a go yourself your will need:

1. Cardboard boxes of different sizes

2. Aluminum foil

3. Old newspapers

4. Black paint and glue (ensure they are non-toxic!)

5. Cooking bag or plastic wrap

The size of box-oven that you need is determined by the size of the pot that you will be using to cook the food, so they should be at least 5 cm higher than container. The main structure consists of two boxes, external and internal. The inner box must be less than the outside at least 5 cm in length, width and height. So you should have a box within a box, and inside that box a pot. The difference in size is 5 cm's between each item. If you start by working up form the pot size first it should be easier.

Coat the entire interior of both boxes with aluminum foil using the non-toxic glue to stick the foil on.  Include the flaps of the exterior box as well. These will be used to direct the sun. Crumple newspapers (which make a good insulator, and won't burn so don't worry.) and place them inside the bottom of the exterior, larger,  box, then put the interior, smaller,  box over it.

Cut a piece of cardboard which is slightly smaller then the base of the interior box, but larger than the pot you will use to cook. Coat this in black paint, or a similar black substance. This will form the heat-sink for your oven. Using a black pot also helps!

Finally construct, or find, a good cover for the whole solar oven.  This should be a plastic covering that is rain and wind proof.

If you are still keeping up, and no doubt getting hungry, you'll be glad to know that it is now time to position the oven. The flaps of the exterior box which you should have covered in foil earlier can now be adjusted on-site so that the sun falls directly onto the black panel inside the base of the interior box. Cutting one away is sometimes useful, and it can be used as a side reflector (see below). Once you have the angle right you can secure it with string. Optionally, you can add side reflectors, made out of left over cardboard and covered with foil, thus increasing the cooking speed.

To ensure that the converted heat doesn't escape you can create a plastic cover for the opening at the top of the oven. The principal at work here is that light travels through glass or plastic, but heat does not (as easily).

There are disadvantages to using a solar oven. They do not work without a strong and pure sunshine and they do not warm the home.  Also it is necessary to chop up food because thick layers may remain under-cooked.

On the other hand, these ovens do not produce smoke that can harm the health, and are ideal for camping in fire risk areas. Sustainable inventions like this are only a small contribution to he many problems facing man's impact on the environment.  It is unrealistic to expect that people will slow down their development and solve the problems of modern times by getting back into the past, but it is possible to create awareness of the power of alternatives, and also the availability of them to those who would otherwise have no ability to cook.

Translated from Serbian into English by Marijana Rakic

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