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This article deals about the making of charcoal.
Charcoal has been made by various methods. The traditional method in Britain used a clamp. This is essentially a pile of wooden logs (e.g. seasoned oak) leaning against a chimney (logs are placed in a circle). The chimney consists of 4 wooden stakes held up by some rope. The logs are completely covered with soil & straw allowing no air to enter. It has to be lit by introducing some burning fuel into the chimney; the logs burn very slowly (cold fire) and transform into charcoal in a period of 5 days burning. If the soil covering gets torn (cracked) due to the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air to enter. Modern methods use a sealed metal container, as this does not have to be watched lest fire break through the covering.
Why charcoal ?
Template:Move An obvious question to ask is why we need charcoal. The answer is that as an energy source, it's more energy dense, and most importantly, the calorific value is higher (heat per weight). This means that a higher temperature can be achieved.
This makes has made the fuel more suitable than wood for transport purposes, atleast if it is burned as is (ie for fueling a steam engine). If it was to be compared to ie a wood gas system, the total amount of energy that can be extracted from charcoal (which is also the original source of charcoal) would without question be lower than that of wood. Perhaps confusing at first glance, this can be explained quite simply: energy is needed to transform wood to charcoal (the first burn (or the "pyrolysis") will waste allot of energy. Also, a wood gas system is much more efficient overall (steam engines are only 15% efficient, IC engines are 30% efficient).
For other tasks as blacksmithing, firing of material (ie using a kiln, casting, ... charcoal is the only natural material that can be used (wood can not be used). Nowadays, blacksmithing is no longer practiced much, and for casting and firing materials, other (non-natural) materials are being used instead (usually as it allows to better control the temperature, use more efficient kiln/forge designs, ...)