Less smoke, more income
The smoke from charcoal production has valuable ingredients.
04 December 2019 | Agriculture
A total of 157 guests came to Farm Aimeb north of Outjo to explore options for the modernisation of Namibia's oldest biomass industry.
“We know that smoke is a problem and we are addressing this,” said NCA manager Michael Degé.
“We understand that there needs to be a financial incentive to reduce smoke.”
The smoke from charcoal production has valuable ingredients. The NCA has started a practical research project to develop a simple and robust set-up with which producers can harvest by-products from smoke and significantly increase their income.
Eben Visser, a chemical technician from Outjo, built a distillation unit that harvests wood acid and tar. The smoke travels through a condenser pipe and a black box into a chimney.
In the black box, tar and wood acid are collected. Each burning cycle produces around 40 litres of wood acid.
According to the NCA wood acid, and specifically humic acid derived from the wood acid, is a food for soil bacteria and therefore reduces fertiliser input. Both wood acid and tar can be used on farms or sold.
Up to four kilns can be placed around the distillation unit.
Estimates are that producers can double their income through the by-products. The desired side-effect is that smoke emissions are minimal.
The NCA says that in the field 90% of charcoal producers are using the traditional round kiln. It is robust, and as it can be rolled, also mobile. Extensive tests have been conducted to find ways how efficiency and quality can be improved while using traditional kilns.
“It's all about fire and air. The way we burn has a huge impact on productivity and quality,” says Pieter Potgieter, a technical expert on charcoal production technologies.
“With the 24-hour cycle you can use your day fully and increase your production significantly.”
The NCA explained that wood needs to be sorted into piles of big, medium and small pieces.
The day starts early, at 07:00. The kiln is filled up to a 60cm height with big pieces of wood.
They burn for one hour. The kiln is then filled fully and the lid slightly closed. At midday the bottom is closed off completely and at 17:00 the top is fully closed.
It is important to open up the kiln before sunrise the next morning, so that the sun does not heat the metal and reignite the charcoal.
According to the NCA tests have shown that the 24-hour cycle improves efficiency and quality. Traditionally, 1.2 tonnes of charcoal are produced per kiln per month.
The 24-hour cycle produces 100 kilograms per day, which adds up to 2.5 tonnes when calculated on 25 working days per month.
In terms of quality traditional burning produces around 67% braai charcoal and 33% fines.
The 24-hour cycle can produce up to 80% braai charcoal and 20% fines.
For producers who value the mobility of the traditional kiln, the next upgrade would be the so-called NAM3. It has air pipes and thus mimics the set-up of a retort. At the same time it is mobile and can be rolled. The NAM3 can produce 150 kilograms in a 24-hour cycle.