simple methods, low-cost equipment
Making char is easy, needs no equipment, and is relatively safe.
Ancient Art Media
35,000-year-old charcoal sketch
Chauvet Pont d'Arc, southern France
As kid chemist, with test tube and gas burner, I "coked" wood splints into gas, char and tar. My test tube was ruined by residues of thick, sticky, black tar.
Charcoaling is an ancient craft and traditional industry. Humans worldwide made char for millennia in nearly every culture, sometimes by a thriving rural industry, and used it for wide assortment of purposes.
In the eastern United States, most forests were cut and burned in earth-covered heaps or stone kilns to make char and potash. Char had many uses as fuel for cookstoves, blacksmith forges, foundries, and industrial smelters, so markets for char were huge and steady. Any man with hand tools and a wagon could cut up trees, bury them under dirt to smolder several days, and haul the char to town for cash or trade.
In the 1800s, most of eastern U.S. forests were cut to burn into char and potash. Late in the late 1800s, coal, then oil, became cheap substitutes, and local char industries vanished by 1900. Today, char still has many uses, mostly filtration and purification. At home, its best known as cooking fuel: barbeque briquettes.
With little or no equipment, you can make charcoal in your backyard or in a woodstove. With little education and no tools, anyone can learn to make reliable, beautiful biochar.
Speaking of beauty, charcoal is a simple, traditional art media. Many insist bamboo makes the finest art char. Indeed, char has many varied, practical uses. My Buddhist friends sprinkle char around their temples to soak up bad spirits. Asian farmers feed char to cows for stronger digestion and reduced methane.
At another extreme, charcoal dust was an ingredient in early gunpowder. American farmers till horticultural charcoal into soil to soak up toxic chemicals after accidents and overdoses. Activated charcoal water filters are common in American households.
For centuries, char was easily made in a simple pit, pile, or masonry kiln. Metal burners with variable air vents, chimneys, retorts, and gas taps are modern innovations. Recently, scientists developed high temperature, high pressure pyrolysis systems that can render urban waste into oil, gas and char.
But only in the last decade has the idea to put char in soil gotten any attention. Even among horticulturists, few know roses and orchids love to have charcoal around their roots-or why.
Today, we must re-invent this technology on a larger, landscape scale as local industries producing enough biochar to spread on gardens, farmlands, fields, even forests. We also must create biochar-burners that minimize air pollution, and biomass harvest methods that avoid turning the land into bioenergy plantations. This requires thousands of tons of biochar, but as we begin the 21st industry, making a few hundred pounds will teach us the basics, and yield enough for small test plots.
We also must learn to capture burner exhausts to re-process into biofuel and chemicals. We need to study this process, and learn to control and manipulate it for various applications. Especially, we need to explore household, garden and farm-scale methods and uses.