How to Start Solar Cooking

Are you interested in reducing your impact on the environment but don’t know what to do other than turning off lights and driving a hybrid car? Why not try solar cooking? Solar cooking is fun, easy and can cook some foods better than a traditional oven. The most important benefit, however, is the fact that solar cooking requires no electricity or fossil fuels and is absolutely free. According to Sierra Pacific’s appliance usage guide, the average oven uses 750 kilowatt hours per year or 12,200 watts. By comparison a ceiling fan uses 43 kilowatt hours per year. Con edison in New York City currently charges 20.09 cents per kilowatt hour. Thus it costs an average of $150 to run an oven per year.

That may not seem like much but if you can save the money, why not? Typically Americans eat two hot meals per day. With a solar oven you can cook one of those meals, thus reducing oven usage by half. It is possible with more than one solar oven to cook both meals each day and give the oven a day off! Not only will you have lower electric bills but you will also reduce your environmental impact. While we traditionally think of smoke stacks and car exhaust when we think of air pollution, we often forget that electricity also produces air pollution. In orded to generate electricity you need to turn the turbine of an electric generator at a power plant. Some turbines are powered by wind or the hydroelectric power of a dam and thus do not pollute. The remaining plants boil water and harness steam power to turn an electric turbine. Boiling water means using a heat source. Again some heat sources do not pollute like nuclear power and geothermal energy but the vast majority of power plants burn oil or coal to create electricity. Using a solar oven thus reduces the demand for electricity or natural gas and conserves these resources while not polluting.

The science of solar cooking and that of global warming are essentially the same thing. Light can pass through a transparent substance like the atmosphere, glass or plastic. Light is converted to heat when it strikes a non-reflective surface. Heat cannot pass through the above transparent substances and thus becomes trapped. Trapped heat in the atmosphere is what keeps the planet from being an ice cube The problem with global warming is that there is too high a level of greenhouse gasses in the atmosphere and thus too much heat is trapped against the planet, changing the climate. In a solar cooker the same principle is harnessed to cook food. Ever gotten into your car in the middle of a sunny July day? Cars in direct sunlight can reach temperatures near 200 degrees in the summer time and almost 100 degrees in the dead of winter.

In such a situations a car acts as a low-grade solar cooker. Light passes through the windshield, strikes the upholstery and is converted to heat which can’t escape through the closed windows. All you need to create a solar cooker is a dark substance, insulation and a transparent surface. The simplest solar cooker that I have ever heard of was made from two tires, a piece of ply wood and a plate of glass. The two tires are bound together and affixed to the piece of plywood, which should be painted black to maximize efficiency. Placing the sheet of glass on top of the tires completes the cooker. Such a cooker should be angled toward the sun and repositioned to follow the sun as it moves across the sky. On a sunny day this simple solar oven can reach about 300 degrees. In this article I will discuss a few other simple solar cookers that anyone can make.

The simplest design of solar cooker is the panel cooker. I own a panel cooker that I bought from www.surferchef.com for about $25. I bought my cooker when I did not know how they were made. My cooker works fine but in the future I plan to construct my own. A panel cooker is basically two surfaces: a black surface and a mirrored surface joined by a hinge. The black surface is where you put the food. The mirrored surface reflects additional light onto the food. In order for this whole contraption to work you need to use bags. Today I cooked garlic chicken drumsticks using nothing but bags, my solar oven and sunshine. I placed the raw seasoned drumsticks in a freezer bag from which I had sucked most of the air. I think placed a second bag puffed up with about two inches of air on top of the chicken bag. I then placed these two bags inside an oven bag and then twisted the end of the oven bag, placing it under the food.

Thus sealed off from the elements I place the food on the oven and pointed it at the sun. The bags receive double sunlight from direct exposure to the sun’s rays and from the reflector panel. The inner most bag receives the light, which is converted to heat when it strikes the chicken. The food is heated in this bag while the air bag and oven bags act as insulators, preventing heat loss into the atmosphere. I would say my chicken took about three hours of direct early afternoon sunlight though I left them out there for longer to be sure. You can not burn or dry out your food using solar cooking because there is no flame and the moisture is trapped by the bags, thus there is no worry about timing. You can construct a panel cooker using nothing more than cardboard, paint and tin foil. Take a large piece of card board and fold it in half. Paint half of it black and tape tinfoil to the other half. You will need to use something to angle your reflector. A piece of coat hanger wire can probably do the job nicely.

A more sophisticated and more effective solar cooker is a box cooker. A box cooker traps heat more effectively than a panel cooker and can accomodate more food. The tire cooker essentially employs the principles of a box cooker. You can construct a light weight box cooker using cardboard boxes, however. Simply take a cardboard box and paint the inside black. Next place take another box of comparable size but slightly larger. Line the bottom of this large box with some form of insulation (more card board can easily do the job. Place the painted box inside the larger box and stuff more insulation between the sides of the two boxes. Next you will need to find a clear substance to place over the top of the black box. Clear plastic affixed to a cardboard frame would work for this purpose. Once you have the top the next step is to create reflectors. The cardboard flaps of the outer box can be used for this purpose. Tape some tinfoil onto the flaps and your just about done. The flaps will reflect more light into the box and also allow you a greater range for capturing light, which will help you avoid having to adjust the angle too often. A well made box cooker will cook much fast than a panel cooker. On a clear, sunny day a box cooker can rival a conventional oven in cooking time.

The most advanced type of solar cooker is the parabolic cooker. Parabolic cookers are heavy duty solar cookers. They are more difficult to construct and operate and they can be dangerous if not carefully managed. In defending the city of Syracuse from the Romans, legend has it that Archimedes employed parabolic mirrors to harness the sun’s rays and set the Roman ships on fire. With a large enough parabolic mirror you can harness a great deal of heat. The most common, low cost parabolic mirrors can be made using an old sattelite dish. Attach a quality reflectorized surface to the dish. Sunlight will be concentrated at the focal point. Placing a cooking vessel at this point will allow you to harness the focused light for cooking. If the dish is large enough and the reflectors are clear and well focused you can boil water in a kettle in about ten minutes. Of course with a parabolic cooker you need to follow the suns rays much more closely but since your cooking time is so much shorter, attending a parabolic cooker is like attending any other oven.

If you are looking for a way to become more environmentally friendly, solar cookers are a great start. Why not try making one or buying one from the internet? You might find yourself with a fun new hobby.

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