by Cody Lundin
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)
Space blanket or roll of heavy-duty aluminum foil
Sharp knife and scissors
Glue
Duct tape
Clear plastic, turkey-size oven bag
Scrap piece of wire
Like anything new, solar-oven operation takes a little getting used to. Sometimes it's necessary to move them a couple of times to make the most of the shifting sun, and during very windy days, the one featured in the photo section will blow over unless it's anchored down. Where you live will depend on how often you can use your oven throughout the year.
Cooking Tips and Techniques for Getting the Most Fuel Bang for Your Buck
All fuel sources after an emergency will be like gold. Whether it's gasoline or firewood, its presence is like money in the bank for the savvy survivor. Knowing how to make these precious resources stretch is all-important.
The efficiency of a heat source used for cooking can be thought of as having three parts. The first part is the efficiency of combustion of the fuel and the second is the efficiency of heat transfer to the cooking container. The third variable is the competence and skill of the person doing the cooking. Over all, maximizing the second variable will result in the greatest fuel savings. Use the techniques listed below now to save energy and get yourself accustomed to doing more with less.
Many of the following tips can be incorporated into cooking over a campfire as well. Outdoor campfires will be under the influence of weather variations and require much greater attention to variable number one when compared to a premixed propane-fueled stove that's used indoors.
Choose a good pot! Broad-bottomed pots are better than narrow ones. Thick metal takes more time to heat up but also holds and radiates more heat when the heat source is removed. Pots with short handles on either side, as opposed to one long handle, will be easier to incorporate into a hay box (featured next). Your pot must have a lid.
Keep a lid on it! Hot air rises. Food cooks much slower in a pot without a lid, thus it uses the same amount of fuel but for a much longer duration. The same amount of heat enters the pot but less of it is used for the cooking process, hence an uncovered pot is a less successful heat exchanger. Lids should be tight fitting to keep the steam inside the pot. Lids can be insulated by putting several layers of aluminum foil in or on the lid. When the lid becomes hot, turn down the burner but keep the lid on.
Wear a skirt! Use a noncombustible, reflective skirt of double or tripled layers of heavy-duty aluminum foil or unpainted, ungalvanized aluminum roof flashing to encircle the cooking flame and pot, reradiating otherwise lost heat toward the sides of the pot. This increases the heat transfer value for the same amount of fuel. The skirt can be as tall as the pot on the stove with about half an inch to a quarter of an inch of clearance away from the sides of the pot. Double up the material encircling the pot a few inches and anchor it with a large metal paper clip. Some folks simply put a large metal mixing bowl upside down over the entire cooking pot.
Shorten the distance! Keep the cooking container as close as possible to the heat source without suffocating the flame from receiving oxygen.
Keep the heat focused! Flame blasting up around the edges of a pot is wasted. Turn the burner down until the flame is focused upon the middle of the pot, yet covering as much surface area as possible. Smaller flames may take longer to cook but will yield greater cooking results for the fuel consumed. Doing so will also eliminate much burnt food stuck to the bottom of the pot, thereby saving food and washing time.
Center the pot directly over the cooking flame! This sounds like common sense but check out where the pot is located tonight at dinner. Ninety percent of the time it's off to one side of the flame.
The Hay Box: The Power of Heat-Retained Cooking
Precious fuel creates the heat that is then used to cook your food. But what if you could harness the heat from the food in your pot to do some of its own cooking? Doing so would allow you to turn off the stove that much sooner, thereby maximizing limited fuel resources. This heat-retention cooking concept is exploited to its fullest by using something which is commonly referred to as a hay box. A hay box is nothing more than a superinsulated box in which food that has been heated to cooking temperature is placed to continue cooking. Its fuel savings, depending on the type of food and how much cook time it requires, can be from 20 to 80 percent! The longer a food item takes to cook on the stove, the greater the savings when using an insulated cooker. Insulated cookers can be used anytime, not just after emergencies, to save a tremendous amount of cooking fuel and energy.
The concept behind insulated cookers is simple. When food in a container is put near a heat source, the food climbs to the boiling temperature and then stabilizes. The food within the stabilized temperature then "cooks" for a given period of time. Any heat beyond the boiling temperature is merely replacing heat lost to the surrounding environment by the pot. When the container reaches its top temperature and then is removed from the heat source and placed in a superinsulated box, the food inside continues to cook. In heat-retained cooking, food is brought to a boil, simmered for a few minutes depending on the particle size of the food, and then put into the hay box to continue cooking. (Simmer smaller grains such as rice for five or six minutes. Simmer larger food such as dried beans or whole potatoes for fifteen to eighteen minutes. Presoaking and draining beans always mak
es them easier to cook, as well as to digest. Red meats such as a roast can be simmered for twenty to thirty minutes. Note: As a safety precaution, meats should be recooked before serving.) The insulation prevents most of the heat in the food from escaping, thereby eliminating the need for a continued heat source for cooking.
As a general rule, hay-box cooking times are usually one or two times the regular cooking time on a stove. It's like having a free crockpot, cooking the food and keeping it warm, without burning the contents, until you're ready to eat. Like many techniques in this book, experimentation will prove what works best.
Making a Hay Box
Quickie hay boxes can be made by wrapping up a cook pot with extra blankets, pillows, or sleeping bags. However, as the pot will be very hot, there are a few rules to follow when making or improving your heat-retaining cooker. Essentially, a hay box is any heat-safe insulating material that can be safely wrapped around a pot. Four to six inches of insulation is best, although it depends on the type of insulation, as not all are created equal. Several kinds of insulation have been used such as straw, hay, wool, feathers, cotton, rice hulls, cardboard, Styrofoam peanuts, newspaper, fiberglass, fur, papercrete, rigid foam, and others. Whatever insulation is used should fit as closely as possible to the pot for maximum efficiency. Using aluminum foil or a reflective space blanket against the pot will not only protect the insulation from some of the pot's heat but will reflect the long-wave radiation (heat) back to the pot. Heat-safe insulation can be placed directly around the pot after putting the pot in a cardboard box or it can be stuffed between two boxes and the pot placed inside the smaller box, among numerous other variations. Some people create an insulated kitchen drawer as a hay-box cooker. After simmering on the stove, they simply pop the pot into the drawer, fold the insulation down around the top, and shut the drawer while dinner cooks.
Rules for Optimal Insulation
You can get away with a lot and still have a heat-retaining cooker work well but, by adhering to the following points, your hay-box cooker will be superefficient at maximizing trapped heat. The insulation for your hay-box cooker should have the following characteristics:
It must be heat resistant and withstand cooking temperatures of up to 212 degrees F (100 degrees C), the boiling temperature for water at sea level.
It should maintain an adequate loft. Even the best insulation can be compromised by squishing it up tightly or spreading it out too thin.
It must be pliable or custom-fit to the cooking pot itself in order for it to fit around the pot as closely as possible to minimize heat loss.
It should not release any toxic fumes when heated. Some foams will need to be protected and should not be used directly against the pot.
It must be kept dry. Rising steam from the pot will dampen insulation, thus causing it to lose some of its insulating properties. Mylar space blankets or aluminum foil can pull double duty as a reflective and moisture-proof barrier.
All cooking containers should have tight-fitting lids to prevent the escape of heat and moisture. The larger the cook pot, the more thermal mass it will have, thus it will store a greater amount of heat to cook food after being removed from the heat source.
Other Hay-Box Advantages
Conserving fuel is not the only gift a hay box can give. Preparing multiple meals can be a hassle with a single or even a two-burner camping stove. Hay boxes allow you to simmer items for a few minutes and then stash them away to cook further, thus freeing up the burner to heat other dishes for the meal. Since water won't be simmering away, you'll require less stored water to cook grains and legumes. Because of this, reduce added water to foods by one quarter. If dried beans require two cups of water for cooking, try using one and a half cups instead. Hay boxes cook food using reduced temperatures, thereby preserving more of the food's original nutrition and flavor.
The Survival Kitchen
Survival kitchen: anyplace you happen to be that is used to prepare food after a catastrophe.
The following tidbits can make life a lot easier when needing to feed the herd. No doubt trial and error will go a long way in your learning curve toward doing more with less under very great stress.
Kitchen Control
In the outdoors, there is nothing worse than a student haphazardly walking over prepared food, especially in sandy conditions. The "sand sandwich" leaves much to be desired. After emergencies, when kitchens must be created in unconventional areas, it may be necessary to set up boundaries to keep things sanitary and prevent kids and pets from knocking things over or creating major first-aid episodes.
Kitchen boundaries can be objects on the ground, such as coolers and tables, or consist of string or surveyor's tape stretched out around the kitchen perimeter, similar to a crime scene. String or rope can also be used for hanging towels or other implements to dry and sanitize in the sun.
The Deluxe Dishwashing Station
After the paper plates run out, washing the dishes for a large family without modern conveniences can be interesting. You will want to stay on top of dishes or they will attract unwanted critters. Dirty dishes lying around are a morale killer in general. I have seen the following method used to service hundreds of people at a time in the outdoors. The more people, the more the water, soap, and chlorine will need to be changed.
Get four containers that hold enough water to fit your dishes into. If nothing else, five-gallon buckets work great. Some folks add one more container at the beginning of the line that serves as a receptacle for uneaten food and table scraps. (If you're not eating what's on your plate during a survival situation, close this book immediately and go watch TV.)
The buckets or containers function as follows:
1 The prerinse. This one is filled with water and takes the major goop off the plate to extend the life of the next container.
2 The washer. This one is filled with hot potable water, soap, and a pot scrubber if you have one.
3 The rinser. Yep, filled with plain potable water.
4 The disinfector. This container is filled with potable water to which a couple of capfuls of chlorine bleach are added. Depending on how much water you have, use about one part chlorine bleach to ten parts water. The disinfectant rinse should smell like chlorine and be prepared fresh before each use after mealtime. If it doesn't smell like chlorine, add more. A bleach water rinse followed by air drying is the simplest way to effectively sanitize pots, pans, and utensils. Boiling water is another option but much more fuel consumptive and liable to cause accidental burns.
Change the water as needed depending on the number of people using the dishwashing station. Get the buckets off the ground to keep animals and small kids out of them. If the rinse water starts to get sudsy early, knock back on the soap in the washing container so the rinse water will last longer. Too much soap residue left on washed dishes can also cause diarrhea. You may want to prepare your wash station before preparing the food. This allows you to wash kitchen utensils as you go and the containers can be refreshed quickly when needed.
While this might seem like a lot of water to use to wash dishes (and it is if all of the containers are full), fill the containers with only as much water as your family needs. You'll figure it out after the first time or two.
The Desert Deluxe Dishwashing System
In my arid region, the above method would be unacceptable unless attending a Rainbow Gathering or a heavy-metal concert. Deep in the wilderness, when hauling potable water is a pain, and even at my house, we wash dishes in a far different way. Personal bowls are half-filled with potable water. Using the spoon you ate with, swish and scrape the bowl until it is clean, thus cleaning the bowl and spoon. The "dishwater" is then drunk on the spot. The dishes are then laid out in the sun to disinfect.
The quicker you wash your dishes, the easier they will be to clean. At my house I use cold tap water (and rarely any soap) to wash dishes, which I do immediately after eating. I then lay them out to dry, and the collected dishwater is periodical
ly poured onto plants in my xeriscape garden. The food particles never sit long enough to turn into a bacterial nightmare, and the drying dishes likewise don't become a habitat for anything funky that might want to propagate. The better you clean your plate when eating, the less food you'll have to wash off. While not recommended, there was a gentleman I knew of that had his dog do the dishes, after which he would stack them back in the cupboard—no doubt a single guy.
Chilling Out
Conventional refrigerators are a fairly recent invention. Both of my grandparents utilized basements and root cellars to keep food cooler during the year, and I remember standing in both with flashlights and radios due to tornadoes. Almost every household should have a cooler that can be used to store food in a pinch. Keep it outside in the cool of the night and bring it back inside during hotter day-time temperatures and store it in the cooler part of the house. In the wintertime, keeping food cool is sometimes not the problem, it's how to keep it from freezing—better frozen than not cold enough, however. Many times a cooler will prevent foods from freezing unless the temperatures are extreme, as insulation works for both hot and cold.
The easiest way to not rely upon a refrigerator is to not need one. Canned goods of the proper size ensure there will be no leftovers. Store dried or freeze-dried foods and prepare only what your family will eat at each meal, unless it's something that doesn't require refrigeration such as bread. While the eat-as-you-go method takes more time and uses more fuel, it's better than dancing with diarrhea from staphylococcal enteritis or some other busy bug.
