Charcoal from invasive alien tree species

By Vuthisa

We recently concluded a feasibility study into the viability of rolling out portable metal kilns to eradicate invasive alien tree species. The cattle farm in question is situated in Franklin, approximately 30 km North of Kokstad, KwaZulu-Natal, South Africa. To achieve this task we adapted the Portable Kiln system and made it into sections in order transport it up onto the mountain top where it was assembled, ready for use. This is a self-funded trial to determine if it is feasible to convert jungle Wattle plantations into charcoal in order to alleviate poverty and transfer skills and ultimately establish Community Based Organisations (CBO’s) …AND preserve our rich species biodiversity!

A single Trans-Portable kiln can process 550 kilogram feedstock into approximately 100 kg charcoal (un-sieved) or 50 kg sieved charcoal in a single 24-hour shift. We have since increased our daily yield by increasing the kiln diameter by 40% and adding conical lids and chimneys to increase yields and clean up emissions. The new retort dubbed the 3-drum Biochar Retort can also accept 3 perforated 55 Gal oil drums which is filled with smaller diameter feedstock in order the produce bona fide Biochar, obtained with a substantial reduction in emissions and a 25% yield. We processed a mix of exotic invaders from Australasia Acacia mearnsii (black wattle) and Acacia decurrens (green wattle) on the private farmers’ land and rehabilitated 6 hectares of this jungle back to pristine grassland. We had up to 8 kilns on the mountain. The felled timber was prepared and stacked in piles measuring 1 m (L) x 1 m x 1 m (H) or approximately 280 kg (617 lb) per pile. We had a staff compliment of about twelve people, divided into clearfelling (and stacking) and burning teams. All of the bags (5 kg) produced were sold in Pietermaritzburg, Howick, Margate as well as Durban.

Overall we were quite happy with our feasibility study having been able to test the kilns for durability, conduct valuable market acceptance trials, gather cost breakdown per activity which is invaluable when project is finally scaled up.

Below are some late afternoon vistas of the farm following a thunderstorm, blessing the area with much needed precipitation. This is a very beautiful and picturesque farm and with the invasive wattle eventually removed it will be a polished diamond indeed, as seen through the eyes of the first inhabitants of the area.

For more information contact us.

The Vuthisa Team

(BEE rating: Level 4)