Greg gave a most interesting "chatty" presentation, where he stood in front of our members, and with minimal props other than half a dozen or so A4 prints which were sufficient to illustrate his progress from very basic furnaces that he had built from scrap steel, to the current much more efficient reduction furnace, (seen in the images below) which is mounted on a trailer for mobility.
He admits that his equipment is "grass roots" stuff, as not only would he have problems finding feedstock for a commercial unit, but the cost to him as a sole operator would be prohibitive.
His production is limited to the winter months, due to the serious bushfire hazard that his equipment presents during the drier months. One would therefore assume that he probably uses a significant amount of his available time to stockpile feedstock (some of which may need to dry over the following year), before he is able to feed it into his furnace.
The design of his reduction furnace uses a small amount of the feedstock as fuel (and raise the temperature several hundred degrees). After the volatile oils etc. have been driven off, and burnt, thus keeping the oven temperature high, the resultant char drops to the bottom of the furnace where it is starved of oxygen, and little biomass is lost. A continuous, regulated supply of feedstock to the top of the furnace keeps the temperature at an appropriate level. The process continues until the furnace is full, whereupon the fire is extinguished, and the load is dropped into the supporting trailer.
A little about biochar…
Charcoal, treated in this way, has an exceptionally long life, and an even greater surface area. The structure of the char is like a miniature honeycomb, this massive surface area throughout the honeycomb attracts not only water, but minerals and beneficial bacteria, and these are available to the fine feeding "hair" roots of plants growing above. The small piece of char below provides a glimpse into this exceptionally fine structure that is normally hidden and underground.
An interesting video is available here, showing how one local orchardist has made good use of biochar to greatly increase his orchard production and health.
Greg's website can be reached at this address.