When All Hell Breaks Loose (75 page)
Read When All Hell Breaks Loose Online
Authors: Cody Lundin
There are three basic types of solar cookers:
box cookers, panel cookers
, and
parabolic cookers
. Box cookers are probably the most common variety and can evenly cook large amounts of food. Some communities use homemade box-cooker ovens that hold and roast an entire turkey. Reflectors can be added, like the petals of a flower, to further focus the sun's rays into and around the solar cooker "belly" where the food rests. Panel cookers consist of various flat panels that focus the sun's rays onto a container inside a glass bowl or clear plastic bag. These can be made very cheaply with few materials. Parabolic cookers are reflective concave discs that focus the sun's rays onto the bottom of a pot. They are more complicated to make but follow the same principle as my Radio Shack solar cigarette lighter that I use for fire demonstrations. Parabolas you may have around the house that can be used to make a fire are the inside reflective bowl of a good-sized flashlight or the reflective bowl from the inside of a car headlight. Parabolas focus the sun's rays into a concentrated area and can cause wicked eye damage to people who insist on using their lighter to see how much gas they have left in their fuel tank.
As a general rule, solar ovens take about twice the cooking time as a conventional oven. One of the beauties about box cooker ovens is you really have to work to burn something in them. Point it toward the sun, put the food in, adjust it once or twice as needed, and walk away—the perfect free crockpot. A friend of mine sets up his solar oven and points it south before he goes to work each day. Upon returning from work, his food is cooked and he sits down to a hot meal each evening.
They also work well to simmer or at least pasteurize nonpotable water. Commercial solar ovens and many homemade ones are so efficient that even hazy days or the reduced insolation of the winter sun simply adds a bit more cooking time to yet another amazing meal. The taste of food cooked with the sun is "pure," and hard to describe as there is no taste hint of any fuel that you get with other methods.
The Perfect Pot
HERE COMES THE SUN
In many countries, poor residents (mostly women and girls) are forced to walk for hours each day to find firewood (a scarce commodity for two billion people in developing countries). When wood is scarce, people have to burn dung and crop residues which would otherwise have been composted to enrich poor soils for growing food. The time involved gathering fuel to cook food takes away from their educational opportunities, such as school or from learning various trades for greater independence, and sets them up for violent assaults common in locales such as Darfur in Africa.
Sitting around a poorly burning camp fire each day is not healthy, as the chemicals in smoke cause long-term health effects. If solar ovens, which don't produce toxic smoke and can also pasteurize unsanitary water, were used in these countries, countless children would not be killed by waterborne and smoke-related diseases, which are the primary killers of children in developing countries. Poor urban families spend a good part of their meager paycheck on cooking fuels. The European Commission as well as solar cooker experts estimate that 165 to 200 million households could benefit from solar cookers.
Today hundreds of thousands of solar cookers are being used on a regular basis, mostly in parts of India, China, and Africa. Slowly but surely, thanks to organizations such as Solar Cookers International (SCI) and many others, solar cooking can and will liberate hundreds of thousands from dependence on dwindling wood supplies, saving countries from continued environmental degradation and pollution caused from processing and burning human-made fuels, as well as saving families money and increasing their health. Far more than just a cool survival option, solar cookers can literally revolutionize the world and empower people with the free and limitless energy of the sun.
There are many opinions about what type of pot to use in a solar cooker. Here in the desert, it doesn't seem to matter much. Dark-colored metal pots won't reflect as much long-wave radiation as shiny pots, but I've used both and they both work. Clear or colored glass works, too, as well as Corningware. If all you have are shiny pots, and you feel strongly about using a black pot, using it to cook over an open fire a few times will solve the problem, maybe forever. As a general rule, use dark-colored, shallow, lightweight metal pots.
Making Your Own Solar Box Oven
There are several designs in books, magazines, and on the Internet for making your own solar oven. For our purposes, we'll make one out of cardboard although you can use much more expensive materials if you wish. Paper burns at 451 degrees F (233 degrees C) and your oven won't get that hot. Cardboard works great unless it gets rained on, but hey, this is a solar oven so what's it doing in the rain? If you expect frequent moisture or want greater durability from your cardboard oven, paint the outside with house paint.
The Robbie Rubbish Radically Right-on Radiant Range
Robbie dug deep into the landfill of opportunity to come up with this solar oven design. He knew from looking at other designs that the cover or top of the solar oven was the biggest challenge to create. To avoid this pitfall, he used a box with a lid. Robbie said he found a bunch of heavyweight cardboard boxes with lids at printing shops and copy centers, as that's what their paper comes delivered in.
The inner walls of Robbie's oven are covered with an old reflective space blanket, although heavy-duty aluminum foil works great too. (Robbie knows that the smoother and shinier the surface, the better it will reflect radiation, so he chose the salvaged space blanket.) The space blanket or aluminum foil reflects the impending long-wave radiation after the shortwave radiation from the sun enters the box. As the heat from long-wave radiation has a hard time getting back out through a barrier such as glass or plastic, it continues to bounce around the interior of the box. He feels this works better than painting the inside walls black. Although the color black may get "hotter" on the oven walls, he's not interested in eating the oven and the subsequent reflected long-wave radiation is a better use of heat.
For the window, instead of using glass, Robbie uses a clear plastic oven bag that can withstand temperatures of 400 degrees F (204 degrees C). He likes to cut the oven bag in half, thus using only one layer of plastic for slightly greater solar gain. You can also leave the bag in one piece so the two sides form an insulating air pocket, but be sure to tape or glue the bag shut or it may collect water vapor between the layers of plastic and block sunlight. Oven bags don't have ultraviolet protection so they will eventually become fragile and need to be replaced, but they are common and cheap enough to do so with a minimum of hassle. Plastic is also lighter and safer than glass, especially around kids.
Robbie's not going to insulate the oven walls, as he knows cardboard is already a decent insulator due to its corrugations. He also knows that heat rises, and will mostly be lost through the oven's top plastic panel which is necessary to let in the sun. He won't insulate the bottom either, although he'll pay attention to where he sets the oven to be mindful of potential colder conduction from the ground. After all, he's dealing with a solar oven, meaning the sun will be striking all around the ground where he sets the oven, warming the surface.
With all the materials at hand, I watched Robbie make an oven in less than forty-five minutes. Follow Robbie's solar-oven instructions or create your own!
Materials
Cardboard box with lid. (The one Robbie found was eighteen inches long by ten inches high by fourteen inches wide)