I did a one day course at CAT using the retort charcoal Kiln last year, My experience was very positive.
As Franakapan noted above any old (dry) timber can be used to start the process, old palettes, brash etc
Once started the system is self fuelling by the charcoal off gasses.
No need to stay up all night with the burn as it is self extinguishing at the appropriate time. That is when the gassing stops.
From my one days experience, the system seemed to be quick. We loaded and lit the kiln by 11:30 and by 15:30 the finished charcoal was unloaded. Albeit sill hot. Best to leave to cool I would think.
We did a burn with a mini ring kiln (45Gal drum)at teh same time and the charcoal from the retort was much superior being evenly processed and low in fines.
The only down side I could see was that the thin (and second hand) steel parts will quickly corrode, At a guess 3 years life.
When I get round to it I will certainly use a similar design, but possibly with some enhancements.
There is a good deal of lost heat and I am considering partly burying the kiln in a large clay bank I have in my wood following a pond excavation some years ago. This should help by insulating the kiln and thus requiring less wood to start the process. This has also led me to consider utilising the waste heat by incorporating a bread oven and maybe even a water heater to feed a hot tub!
Any one know where I can get an old domestic oil tank?
