Smoke reduction, lucrative by-products and a 24-hour burning cycle were the hot topics at a recent field day of the Namibia Charcoal Association. 157 guests came to Farm Aimeb north of Outjo to discover options for modernisation of Namibia’s oldest biomass industry.
“We know that smoke is a problem and we are addressing this,” Michael Degé, NCA manager points out. “We understand that there needs to be a financial incentive to reduce smoke.”
Fact is, smoke from charcoal production has valuable ingredients. NCA has started a practical research project to develop a simple and robust set-up with which producers can harvest by-products from the smoke and significantly increase their income. Eben Visser, 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. Wood acid, and specifically humic acid, derived from the wood acid, is a food for bacteria in soil and thus reduces fertiliser input. Both wood acid and tar can be used on the farm or sold.
Up to four kilns can be placed around the distillation unit. Estimates are, that the producer can double income through the by-products. The desired side effect: smoke emissions of the set-up are minimal.
“Use your day fully”: introducing the 24-hour cycle
In the field, 90 per cent 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, technical expert for charcoal production technologies. “With the 24-hour cycle you can use your day fully and increase your production significantly.”
Wood needs to be sorted in piles of big, medium and small pieces. The day starts early, at 7am. The kiln is filled up to 60 centimetres height with big pieces of wood. They burn for one hour. Then the kiln is filled fully, the lid slightly closed. At midday the bottom is closed off completely; at 5pm 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.
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 kg per day – which adds up to 2.5 tonnes when calculating 25 working days per month. In terms of quality, traditional burning produces around 67 per cent braai charcoal and 33 per cent fines. The 24-hour cycle can produce up to 80 per cent braai charcoal and 20 per cent 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 kg in a 24-hour cycle.
“A new ballgame”: exploring biochar
A certain eye-catcher at the field day was what looked like a giant Chinese frying pan. Grant Blumrick has 8 years of experience in making biochar from bamboo in Malawi and built this model based on the so-called Kon-Tiki kiln. It’s the first of its kind in Namibia.
Setting up a production of biochar definitely is an investment in the future. Internationally, research is booming on how fossil fuel based products can be replaced by biomass based alternatives. Biochar has already been identified as a feed supplement, an absorber in functional clothing, as insulation in the building industry, as energy storage in batteries, as a filter in sewage plants or as 3D-printer ink (more info at www.ithaka-institut.org).
As biochar production uses fine branches, up to 20mm in diameter, or wood chips, it is an ideal parallel process to charcoal production. Fire is started in the middle of the kiln. As soon as ash is produced, more material must be added gradually over the next 4 to 5 hours. Temperatures of up to 700 degrees develop. At the end of the process, around 100 litres of water are needed to extinguish the burning. The model kiln produces around 2 cubic metres of biochar per cycle.
While this set-up is completely new to Namibia and the water usage brings challenges with it, the scope of the product and the potential income opportunities make it extremely interesting: world market prices lie at around NAD 10,000 per cubic metre of biochar. “It’s a whole new ballgame”, Grant Blumrick points out.
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