Low-impact Living at the Elder Grove Homestead

Energy-Wise Cooking & Canning

If you grow your own food, or source it locally, then the next step in saving energy related to food is in cooking and preservation. Reducing fuel use, whatever the source, can be accomplished by changes in your cooking techniques, including heat capture. Here's some of what we do:

Retained Heat Cooking

The hay box cooker, or hot box, is not a new concept. It is a way of cooking that relies on bringing food up to a boil, perhaps to cook for minute, or longer in the case of beans, then wrap/place the pot in some kind of insulation to keep the food hot as it continues to cook itself. Kind of like a slow cooker without the power plug.  In years gone by, the hay box was literally a box filled with hay into which the cook placed a hot pot of food. While camping you may have used this technique with a sleeping bag or an empty cooler with crumpled paper or leaves around the pot. Modern kitchens can be equipped with an insulated drawer or cabinet. Let your creativity inspire you with what materials you have available and sized to suit your needs.

Using this method is so easy!  For instance, dry beans can take an hour or two to thoroughly cook on the stove. Instead, bring the pre-soaked beans to a boil for 10 to 15 minutes (depending on the size of the bean) using whatever form of energy you currently use for cooking (gas, electric, wood, sunshine,...). Next you put them in your hot box cooker. After about an hour, check the beans and, if not cooked to perfection, put them back on the stove to reheat and repeat the hot box.
It is important to note that beans MUST first be boiled to alter a chemical that is especially high in red kidney beans, but found in all of the common beans of the genus Phaseolus. Failure to do so can cause poisoning, as you will find at this link. Definitely read it if you currently use a "slow-cooker", which does not actually reach the boiling point!

Beyond saving energy there are other benefits to using a hot box as part of your kitchen repertoire. The food in a hot box cooker won't burn, freeing you up to do other tasks as you don't need to keep an eye on cooking food. One pot can be in the hot box while you're cooking another dish. This is especially helpful if you're cooking with a solar oven that can only handle one pot at a time, allowing the sequential cooking of multiple dishes. The food will stay nice and warm until you're ready to eat. We use this technique daily and would feel lost (and unfed) without it.

Cooking Directly with the Sun

This photo shows two of the two solar cookers we have used. The home-built one on the left is more of a slow cooker, using a simple mirrored reflector above a glass covered cast iron skillet set in a galvanized pan filled with vermiculite insulation. The parabolic dish on the right focuses the sun's energy enough to boil, fry or bake like a stove top range. It was purchased many years ago from Zomeworks, in Albuquerque, NM. There is a Pyrex bowl at the center with another inverted Pyrex bowl cover on top, making a glass chamber to surround dark-colored pots for boiling/baking. A steel rack that holds pans for frying can be used instead of the Pyrex chamber. Using a sun oven or parabolic cooker requires a sunny day, no matter the time of the year. They need to be periodically turned to stay pointed at the sun to keep temperatures maximized or let them "power down" if you want. During the summer months it is an advantage to cook outdoors to keep the heat out of the house and to harvest free energy.

Cooking with Stored Bio-Mass

Our wood stove is our home's primary winter heat source but it does double duty by cooking winter meals as it can hold a lot of cook pots. In the photo there is rice in one, beans in another, the wok has a veggie stir-fry, behind that is steamer of squash, and the skillet in front with the circular potholder on top is our version of a stove-top oven for flat-breads. You can bake in a cast iron skillet by putting a metal trivet under it, a cover over it, and an insulating potholder or folded towel over that. This was easily enough food for a couple of meals, all on one brief firing of an armload of "box elder" (Manitoba Maple, or Acer nigundum). You can see more details of this stove on our Masonry Stove page.

We also have a Jotul wood stove in our sauna, and when we fire it up we cook our meals on it. The sauna also serves as a backup food dryer and is used to boil down apple cider into syrup. Wood stoves are less than pleasant during summer months but having a "summer kitchen" or sauna allows hot weather use of bio fuel if you have it, especially on days without sun when an alternate fuel source might come in handy.

Cooking Indirectly with the Sun

Low Voltage DC Options

This is one of our 12-volt DC ovens that are powered by our solar photovoltaic (PV) system. When our "off-Grid" battery bank is full we can use some of our excess electrical production to do other useful chores like cooking. So we came up with the idea of building a 12-volt electric oven, using DC electricity straight from the batteries and solar charge controller as DC power is more efficient than using inverted AC electric. The 12-volt commercial models available on websites catering to RV enthusiasts and over-the-road truckers simply were not built to last and were virtually uninsulated.

We initially built this oven using two recycled stainless steel tanks, a "barrel-stove" door kit, four 300-watt, 12-volt, (0.5-ohm) ceramic resistance heating elements, some heavy-gauge wiring, and about 7 gallons of horticultural vermiculite as insulation. The switches at the bottom front each added in one more heating element to the single 300-watt element that was active when the unit was switched on. With all four switched on, burning up 1200 watts of power, the unit could quickly reach over 550 degrees F. This proved to be too hot for this small oven, and we re
built it with three 30-watt heating elements (5-ohm elements rated for 300-watts at 36 volts, which, when run at 12 volts produce 30-watts) and one of the initial 12-volt, 300-watt elements. Now we can switch on 30, 60, and/or 300 watts for a total of 390 watts. The other oven we built is slightly larger and box shaped (it was a laboratory incubator in its previous life). It has one of the 30-watt elements and three 300-watt elements for a total of 930 watts. The 300-watt elements are 0.7-ohm and can handle over 14-volts of input on sunny days without burning out the element. The insulation in both ovens keeps the temperature stable for long periods, greatly increasing their efficiency, and allows them to be used as hot boxes when they are turned off.

Here you can see a pot of veggie stew coasting down to 150*F after cooking at 250*F for an hour. The heating elements are at the bottom, just below a ceramic floor tile supported by three 3/8" steel rods crosswise under the tile. We later replaced the tile with a 1/8" steel plate as the tile proved to be too fragile.

The 12-volt ovens can be operated manually for cooking or set as an automatic "divert load" with our PV controller during the cold months, giving us the option of using them as a space heater when run empty with the door open. Running it as a divert load means that at the end of the day the controller will turn it off and we don't need to worry about drawing down the batteries by forgetting to turn it off manually.

AC Powered Cooking Options for Low Energy Consumption

After an unsuccessful attempt to generate our own cooking gas instead of using compressed propane (LP gas) for some of our cooking needs we tried another approach which has worked quite well. Pictured above are two 120-volt AC electric hot plates, one using 1500 watts, the other 900 watts. We initially bought the one on the right locally and it worked well for most of our cooking but it could not replace gas as a heating source for canning foods. It simply would not put out enough heat once its cast iron top plate reached its maximum temperature, at which point the unit would turn off and on repeatedly to maintain that temperature. So we bought the unit on the left online to use mostly for canning as its output was easily high enough to do the job. Unfortunately it was not built to have a big pot on it for an extended time and the control knobs failed (melted internally?). We have since replaced it with a restaurant-grade hot plate that cost well over $100 and it has worked for many years. If you have an inverter large enough to handle the load, and enough solar electrical input to maintain your other needs even on cloudy days, these hot plates can use the excess solar energy that is inevitable on really sunny days. Induction cook-tops are a bit more efficient but limit you to cookware that is magnetic and are more expensive too, so we went with the older technology. Hot plates are especially handy when intermittent clouds lower the temperature of the direct-solar cookers too much or you don't want to heat up an entire oven for a quick cooking dish.

Low Energy Ways to Can and Preserve

Steam Canning - The Energy-Saving Alternative to Hot Water Bath Canning

Reducing energy use in everyday cooking is important in the overall annual energy budget. And for parts of the year the energy needed for home food processing can be a large part of the equation. So if you do any hot water bath canning, you need to know about steam canning as a low energy-use alternative. A steam canner consists of a shallow pan filled with about 1.5 inches of water. Above this is a perforated rack on which the jars are placed, directly above the water. A deep lid, shown behind the canner, covers the jars to contain the steam. There are a couple of small vent holes near the bottom edge of this lid. The water pan uses a fraction of the water that a hot water bath canner uses and therefore a fraction of the energy required to get it up to boiling. Some have criticized steam canning as an "unsafe" method. You use the same recipes for steam canning as hot water bath canning but the difference is knowing when to start timing. Steam canning times start when you see the two vent holes at the lower edge of the lid pouring steam out horizontally in foot-long streams, not just little occasional puffs. If you start timing when the jars are just placed in the canner, or even with occasional steam puffs, you are seriously under processing which will lead to spoilage or even botulism.

This photo shows a 7-quart batch of heirloom tomatoes after steam-canning. The tomatoes shown are a mix of open-pollinated heirloom red, orange, and green-skinned varieties, and we usually just can them without removing skins or seeds. Their depth of flavor can be further enhanced at the time you open a jar by adding some dehydrated black cherry tomatoes, along with peppers, herbs and onions/garlic, not to mention dried mushrooms, eggplant and summer squash. Our favorite for marinara sauce.

Steam Juicing - Bottling High Acid Juices

Steam juicing is a method of preserving high acid juice and bottling them to make a shelf-stable product for the pantry, to be used over the year for drinking or cooking. We use it for pears, peaches, plums, apricots, grapes, strawberries, raspberries, aronia berries, and tomatoes. Part of the steam juicing method's energy savings is in the bottling method. Bottles such as recycled "Grolsch" beer bottles (or other import brands that have a wire bail closure and a rubber gasket) are filled directly from the steam juicer's hose. To do this you place the bottle in a bowl next to the juicer and fill the bottle until it overflows. Then clamp down the wire bail and place the bottle to cool on a towel, no further processing is needed. Once cooled, just a little bit of rinsing is needed on the outside of the bottles to remove any overflowed juice. Apples can be steamed juiced as well, but since we have many bushels of apples we use an apple press to turn it into cider. The cider is then heated and bottled as if it was steam juiced. For large batches of cider we use half gallon canning jars, filling them to the top and sealing with a canning lid. Steam juicing can also be used as an intermediary step of removing excess moisture from tomatoes to make thicker sauces instead of just boiling off the liquid into the air. When we steam-juice a full pot of tomatoes we get about 7 pints of juice and about 7 quarts of tomato pulp left in the juicer. With so much liquid removed already, canning what remains gives you a ready-made tomato sauce, especially if you use any of the available de-seeding machines (Victorio strainer, etc) to remove seeds and skins. If you don't have a steam juicer, this task can also be accomplished by cooking cut up tomatoes and straining off the juice. The juice can be heated and bottled afterwards as if steam juiced. Bottled tomato juice is handy for soup stock.

This is what a steam juicer looks like. The bottom pan holds about an inch or two of water that boils to make steam using your cook top of choice. The steam rises through the next pan (which looks a bit like an angel food cake pan) which is where the juice collects. Above the collecting pan is a perforated basket of whatever high-acid food is being juiced. Topping it all off is a lid. The silicone hose hanging down from the collecting pan has a clamp on it to retain the juice until you're ready to tap it off. To reduce distillation of water into the juice pan (from a cold cover), we normally use a folded towel on top for insulation.

A juicer load of raspberries - we will remove the pasteurized juice for bottling, leaving the pulp and seeds behind. The pulp-seed mix can be solar dried (on cookie sheets as a "fruit leather") or canned in the steam canner, depending on the weather. Blackberries really need their seeds removed from the pulp before canning or drying as they are larger, more numerous, and more "gritty". A Victorio or Squeezo strainer can be used for this task.


Bottles of juice cooling.

Here you can see the process of preparing some small pears for juicing. The raw product is in the wire egg basket at the top. The knife and edge-sharpened spoon at the bottom left are used to cut the pears in half and scoop out the compostable stems and cores. Cut up pieces of pear are placed in the steamer basket. A steam juicer full of cut pears made over 7 pints of very sweet juice and 4 cookie-sheet trays of fairly dry pear pulp for the solar food dryer. You might not think that this pulp would have much flavor, but even with lots of juice removed the heating that it undergoes during solar drying tends to sweeten it (semi-carmelization) and concentrate the flavor.

Our Book

If you are looking for more detail than can be gathered on our site, check out our book:

Our latest co-authored book, "Feeding Ourselves", now in its second edition, includes our unique solar food dryer and other energy-saving food preservation methods (steam-juicing and steam-canning) that fit into our overall scheme of nourishing ourselves year-round in a fairly harsh climate. This edition has been updated with our years of experiences in raising and utilizing staple crops like gluten-free grains, legumes, and nuts.

To see an Adobe PDF file of the second edition's entire covers and table of contents, just Click Here.

  • Physical copies of "Feeding Ourselves" (184 pages, spiral-bound) cost $23.50 each, postpaid in the U.S. (please add $1.38 sales tax if you are ordering in Minnesota), or $20.00 plus shipping elsewhere in the world. Contact us for international shipping costs. All others can simply send a personal check, traveler's check, or postal money order to:
            GeoPathfinder/Larisa Walk/Bob Dahse
            30319 Wiscoy Ridge Road
            Winona, MN, 55987-5651

  • OR: To order a physical copy of "Feeding Ourselves" using PayPal, Click Here. Clicking this takes you (very slowly if you have a dial-up connection) to a new screen with a "Buy Now" button, and this links to PayPal's secure order form where you can pay by credit card, checking account, or an existing PayPal account balance.
  • OR: To order a downloadable Adobe PDF file of "Feeding Ourselves" for about half price ($10.00), just Click Here (requires a free Adobe Reader download to read the PDF file). Clicking the book download link takes you to PayPal's secure order form and gives you a link to the PDF via Payhip.com. The file size is over 8 MB so, depending on your connection speed, it may take some time to download.