Although virtually any wood species can be used to make charcoal, the most common species in coppice arrangements are alder, oak, and maple. (Hickory makes famously great charcoal but doesn’t coppice very well.) For most people, charcoal is a by-product of other forest activities, and the wood that is used to fire your charcoal oven should be your “worst” firewood or, better yet, scraps left from other projects.
Charcoal can be used for a number of other applications besides barbeque. Both commercial and more primitive water filtration systems rely on the same basic charcoal-based technology to remove sediments, volatile organic compounds, and odors from water. One common method for remote off-grid homesteads employs a gravity-fed charcoal filtration system in which water percolates through a filter filled with ground charcoal, much like a drip coffeemaker.
Using the same process as the lump charcoal procedure described above, you can create charcoal pencils from the twigs, seedlings, and saplings removed as part of your regular tending operations. Load the pencils vertically in a 1-gallon paint can, fitting about 200 pencils per can.
The charcoal-cooking process results in usable by-products as well, beginning with the char-ash left at the bottom of the crucible. This ash can be used as a soil amendment to make acid soils more alkaline. If you choose to make charcoal out of softwood, the result will be a less energy-dense coal; however, you’ll find the bottom of your crucible lined with a thick tar, roughly the consistency of caulking. This cement has historically been used for a variety of adhesive needs but is useful on the modern homestead as a patching material that sticks to virtually anything, including wood, metal, and cloth.
How to Make Charcoal
Charcoal is nearly pure carbon. “Cooking” wood in a low-oxygen environment releases water, hydrogen, methane, and even tar (in the case of softwoods). What’s left after the cooking process are lumps of coal that weigh about 25 percent as much as the original material that was placed in the crucible but are more energy-dense than the original “raw” wood.
Materials
• 55-gallon metal drum for the still
• 5-gallon metal paint can with clench-tab lid for the crucible (or for smaller batches, a 1-gallon paint can with lid)
• Approximately 40 pieces of dry wood to fire the oven
• Dry coppiced firewood 1 to 3 inches in diameter, debarked and cut into uniform pieces. You will need enough pieces to fill the can. This wood will become your charcoal.
Make your oven. Convert your metal drum to a charcoal oven by punching holes in the lower third of the barrel. These holes can be punched randomly, as their only purpose is to provide oxygen to the fire inside.
Construct the crucible. The crucible, which holds the charcoal, can be constructed from the metal paint can. It’s important that the can be clean. Layer the small, debarked firewood in the can, packing it as tightly as possible. The goal is to minimize the chance of combustion by minimizing air space. Drill a 5/8-inch hole in the lid of the can, and secure the lid using the metal clenching tabs. If your can doesn’t have tabs or a closure band, you’ll need to place a weight on the top, as pressure may build within the can.
Build the fire. Place the crucible inside the barrel. Because a fire will have trouble drafting well inside the barrel, you’ll need to start a small fire and build it up slowly. Be sure to use untreated wood. Continue to build the fire so that it covers the sides and the top of the crucible, though you’ll want to make sure that the hole in the top of it is unobstructed and visible. It is very important to keep the fire hot! To achieve the high temperatures required (a minimum of 500 degrees Fahrenheit inside the crucible), you may need to split your firewood into smaller pieces that will burn faster but hotter.
Cook the moisture out of the wood. After 30 minutes or so, you will likely see steam wisping from the hole in the top of the crucible. This is the remaining moisture being cooked out of the wood. As your charcoal nears completion, a small flame will appear from the hole in the top of the crucible. As this last little bit of hydrogen and oxygen burns, you’ll want to pay attention to the crucible flame. Once it goes out, carefully remove the crucible using long tongs, and immediately cover the hole in the top with a damp rag.
Charcoal. Once the crucible has cooled, it’s time for the moment of truth. If you have tended your fire carefully and removed the crucible as soon as the flame burned out, you’ll be rewarded with your own harvest of genuine lump charcoal.
Brett McLeod, a forester and homesteader who lives on 25 acres of his own, tackles the big questions homesteaders have about living off their land, from splitting wood to growing fruits and berries, in “The Woodland Homestead.”More from The Woodland Homestead:
• Building with Trees and Tree Stumps
• Preparations for Splitting Firewood
Excerpted from The Woodland Homestead, © by Brett R. McLeod, illustrations by © Steve Sanford, used with permission from Storey Publishing.
