Whether made in an earth clamp, a ring kiln or a brick oven the basic principle remained the same, a carefully controlled slow burn of a large amount of covered wood. It took years for a charcoal maker to gain a high skill level and even an experienced man could still lose his work if caught out by sudden bad weather or a clamp collapse.
A successful burn produced only a relatively small amount of charcoal that had to be separated from the dirt, ash and blackened wood that lined the bottom of his fire pit. The wood selected for charcoal production had to be stacked and dried for around two years to ensure the right moisture content and then cut to an even size to maximise the chance of a good burn.
At best 6/7ths of this would be consumed to convert the remainder to charcoal. In short, the charcoal made during each burn was the result of many hours of back breaking and very hard work. For most of the history of charcoal making nobody had to worry about emissions or where the wood they used came from. Because only the trunks and larger branches of the tree was useful for making charcoal the remainder, the brash, was typically burnt. The brash could represent as much as thirty percent of the mass of each tree. All charcoal production produces greenhouse gases (methane and similar) and the traditional methods make a great deal of smoke and release nearly all the greenhouse gas produced to atmosphere.
When examined carefully it becomes clear the old methods of charcoal making are very inefficient and polluting The Modern Way.
It is possible to improve greatly on the old ways. The retort method of making charcoal has been with us for about 150 years but has been little used until the last thirty years or so. This is largely because materials with sufficient strength to withstand the very hostile environment a retort creates have been expensive and heavy. Engineers have struggled to control distortion in metals and disintegration in ceramics.
The Carbon Compost Company have overcome these challenges by allowing our materials to behave as they are inclined to do under stress. This machine has been designed to accept considerable distortion without compromising efficient charcoal production. It is also the first fully mobile retort and offers unrivalled flexibility of use.The design has been arranged so that all work is carried out at waist height and much less wood processing is needed. Wood can be loaded in 2 metre lengths and converted green--no drying is required. The machine is very simple to use and requires no skill.
Anybody can safely operate an Exeter Retort after two days of training. It also returns charcoal at a rate of 4:1 by weight at 20%moisture. If you put in 600kg of hardwood you will get 150kg of high quality very clean charcoal in return. Anything from a log to a leaf can be converted to charcoal. There is no part of your trees that cannot be processed in our machine.