Lasted edited by Andrew Munsey, updated on June 15, 2016 at 1:20 am.
Biochar production is useful to reuse waste organic matter. Waste organic matter is converted to biochar which is then used to refertilise the soil. Biochar production units (also called charvesters) are the heart of any biochar system. Aldough besides pyrolysis units, gasification units exist, these are best not used as they require gas (which is a finite source of energy unlike wood). In order to have a clean system, carbon capture and storage is to be added to the unit.
Several (relatively inexpensive) charcoal kilns can be made which can be used to make charcoal/ See the designs at Biochar-international page 1 and page 2 Most of these require atleast some parts which can not be found in a natural environment (ie metal parts). On the upside however, such parts typically last longer and may be more efficient. Some very simple designs also exist consisting of only a few metal parts (ie 2 barrels), see NASA Langley Research Center's low-tech kiln