A Not-So-New Appliance- The Solar Cooker


INTRODUCTION

Nowadays, people cook their food in a wide variety of ways. There are conventional ovens, microwave ovens, charcoal and propane gas grills, etc. Many of these, with the exception of cooking over fire, are relatively recent innovations in cooking science. A far more interesting way to cook food, and one that has been around for a little longer, is through the power of the sun. Called solar ovens, they collect and concentrate to sun's energy into a chamber, and convert that sunlight into heat. Using the converted heat that is now trapped inside the chamber, the food cooks. Easy as pie. In northern climates around the world, solar cookers can be used for about the hottest six months of the year. Around the equator, they can be used year round. What are the different types of solar cookers?

BOX COOKERS

A Swiss naturalist named Horace de Saussure is the first known person to use solar energy to cook food. Horace would cook fruit in his box, with the internal temperature reaching 190 degrees Fahrenheit! The box cooker is the most common type of cooker, at least for personal use. Typically, the inside of the cooker reaches 300 degrees F (150 degrees C). Although this temperature will not be arrived at quickly, the end result is a slow, even cooking process. Even though it is called a “box” cooker, it can be circular, rectangular, or box shaped. The fundamental components, whatever the shape may be, are an inner box which is covered on the top with glass or a plastic sheet (usually an oven bag). A reflector will be affixed to the top to channel the sun rays inside the box.

  • Pizza Box Oven – Great website with detailed, easy to follow instructions on how you can make your own solar box cooker with a pizza box and a few other easy to get items. Good picture, too.

  • Box Cooker Principles – Informative site with drawn diagrams and the principles behind how a solar box cooker operates.

  • Cardboard Cooking – Different instructions at this site, but nonetheless easy to follow. This site also goes into discussion about recent experiments done in Seattle and Arizona with solar box cooking.


PARABOLIC COOKER

These solar cookers can reach cook faster and hotter than box cookers. As a downside, they are much more difficult to build and use. The mirror used to catch and focus sunlight is basically a satellite dish – a concave mirrored surface that channels the sunlight into a central point. When using parabolic cookers, it is necessary to accurately focus the sunlight, otherwise the food inside will not cook. In opposition to box cookers, there is a risk over overcooking and burning the food, and as a result, the internal temperature must be closely watched. Most commercial ovens are a form of parabolic cookers. Another concern is the risk of damage to your eyes, much in the same way that staring directly into the sun will cause injury. The parabolic cooker is not where one should begin their solar cooking journey. Even if the risk of injury to the eye was not a factor (which it is), the complexity and cost associated with building parabolic cookers should warn away beginners.

  • Parabolic – Very informative site with detailed instructions on how to build a parabolic cooker, to include precise measurements and graphics.

  • Dr. Kundapur's Page – Lots of pictures on this site, with heavy scientific information on why and how the parabolic reflectors work more efficiently than other types of cookers.

  • Appropedia – General information site with pictures of parabolic cookers in operation from various places around the world. Good overview on the dangers associated with parabolic cookers as well.

    PANEL COOKER

The most common model is dubbed the CooKit by its creators at Solar Cooking International. The panel cooker consists of fold-able panels that are easy to transport and set-up, making it ideal for use in third-world countries. These panels direct the sunlight onto the pot or other vessel which contains the food. There is no need for the inner box found in other cookers, as the cooking container serves this purpose. The panel cooker is arguably the easiest to construct and maintain, and the cheapest to make. Consisting of only four flat panels covered with reflective material and the food container, they are easy to sustain. Due to the manner in which the cookers need to be set to cook correctly, panel cookers do not operate as well in windy or cloudy environments.

  • CooKit – Solar Cooking International website for the CooKit, with plans, pictures and information about the panel cooker.

  • Florida Solar – Florida Solar Energy Center website, containing drawings, instructions, testing and other information about panel cookers. Tons of pictures.

  • SHE Inc – One the more popular items, the HotPot cooker from Solar Household Energy Inc. is a dark cooking vessel suspended inside a transparent outer vessel. This is then placed onto the panels, as seen at this site.

SOLAR KETTLE

Similar in appearance to panel cookers, solar kettles are for liquid cooking. The internal temperature of these kettle can reach 425 degrees F (220 degrees C)! Unlike some other type of solar powered cookers that require tracking of the sun to maintain the light focus on the cooker, the kettle only needs diffused sunlight to work. Some kettles use evacuated solar glass tubes to capture, build up and store the energy needed to power the kettle.

  • Solar Kettle-Thermos Flask – A very specific type of solar kettle, this device is a very well-designed and cost effective way to pasteurize water in third-world countries.

  • Contemporary Kettles – This sit offers lots of information, to include frequently asked questions, on everything from how to use a kettle to why someone would use one.

  • Alex Kee – Website with pictures, links and an audio interview with Alex Kee discussing his solar kettle invention.

SOLAR BOWL

This is basically a large scale parabolic cooker, without the direct effect of cooking. A solar bowl is an energy accumulator, meaning that it collects the sun's energy and stores it for use. Central to the operation of the bowl is the ability for the sun to be tracked so that the bowl is always pointed at the sun, making it most effective. This is controlled by a computer, and the light is focused along a line on the spherical surface. From this energy, steam is created and temperature up to 300 degrees F (150 degrees C).

  • Auroville – The Solar Kitchen in Auroville, India, uses a solar bowl to cook two meals a day for 1,000 people. This site has lots of information on the solar kitchen.

  • Solar Bowl – Good site with news, designs, pictures, and links on solar bowl technology.

  • Crosbyton – Website with links and information, to include a design drawing to the first solar bowl that was constructed in Crosbyton, Texas.

HYBRID COOKER

A hybrid solar cooker is like a hybrid car – it uses solar energy and electrical energy to cook food. This is not as popular or useful in third-world countries where the power grid is less reliable and less accessible. Part box cooker, it uses a regular electric heating element for use at nighttime or on cloudy days. Another hybrid type is a solar grill, which has a movable parabolic reflector set up with an adjustable surface to grill on. Like the hybrid box cooker, this grill is able to use heat from other sources like electricity, wood or gas when sunlight is not readily available.

  • How-to – Website with detailed instructions on how to build your own hybrid cooker. No pictures.

  • Tulsi-Hybrid – A commercial version of a hybrid oven, this has good pictures and information regarding hybrid cookers in general.

  • Tripod Grill – A recent invention, the tripod hybrid grill illustrates the manner in which solar power may be used, or a fire can be lit underneath the dish for an alternate source of heat.

CONCLUSION

As you have seen, there are different types of solar cookers. There are advantages and disadvantages associated with solar cooking, no matter the design you use. Some of the advantages are the first things that pop into your mind when you begin to study solar cooking. They are cheaper to operate, since they use free sunlight instead of gas, electricity or wood. Along the same lines, since they must be used outside, they do not contribute to the heat inside your house, which is important in the summer months. Solar cookers are also safer to use, especially around children, since there is no danger of fire or being burned. That being said, there are also some disadvantages to cooking with the sun. Meals must be started several hours in advance, often in the morning to be able to eat them by dinner due to the long cooking times. For larger meals, you may require more than one solar cooker in operation at the same time. Depending on where you live in the world, you may not even be able to use them year-round or in inclement weather. For most people, Solar cookers would be a good way to cook sometimes, but the disadvantages make it difficult to use them all the time.




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