|CERES No. 116 (FAO Ceres, 1987, 50 p.)|
Sixteen years ago the Uganda Forest Department decided to fund a research project to develop a more efficient and commercially viable method of producing charcoal, upon which both rural and urban populations depend as a reliable fuel that can be produced economically and simply for domestic purposes. Production methods had remained fundamentally the same for centuries, so improved production techniques were considered of great importance.
The result of that project is the Katugo charcoal kiln, which carbonizes under controlled conditions in a chamber with limited air supply. The kiln, built of locally produced bricks, consists of a rectangular carbonizing chamber with four chimneys set in a domed metal roof. The wood is reduced to carbon while the impurities are released in the form of smoke and gases. The kiln is capable of producing two to three tons of charcoal every six days and has a conversion efficiency of 35 per cent on dry weight basis.
The kiln has rationalized traditional production methods, resulting in a higher yield of better-quality charcoal, and thus helping to balance fuel supplies with increased demand. The improved commercial viability of the kiln has been accompanied by the creation of a more skilled work-force and greater employment possibilities for those concerned.
The purer charcoal produced has a number of positive features: it produces very little smoke, yields two and a half times as much heat as the same weight of dried wood, is very easy to ignite, has a fixed carbon content of over 70 per cent, and leaves ashes which do not exceed five per cent of the kiln weight load.
The most widely used traditional production methods are the "earth pit" and "clamp", both of which require minimal investment, equipment, and skill. The earth pit method involves carbonizing wood in a covered pit. While digging a pit is an arduous task in the dry season in Uganda, problems also arise in the wet season: collapsing earth cover for examples. The clamp method entails piling up the wood and covering it with earth before firing. Both methods are labour-intensive and inefficient: only 8 to 12 per cent conversion efficiency on a dry weight basis is achieved. Due to the inadequacies of these traditional methods, the charcoal produced is of poor quality, with a high level of impurities and an unnecessarily large amount of unmarketable "fines", the residue of charcoal production.
The inefficiencies of the production process are compounded by problems of supply and transport of raw materials and storage of the finished product. The methods used are laborious - trees are simply cut down with axes and carried to the pit. The storage system employed is ineffective - the best charcoal, is raked and sorted out and then simply piled in an open place and covered with leaves. There it becomes damp and hard to ignite. It produces much smoke and becomes progressively more unsuitable for either domestic or industrial purposes.
The new methods do not alter the basic principle of carbonization, but rationalize the use of heat during the process and modernize the production and transportation of the raw material. This is what happened in Uganda.
The carbonization stage is, of course, only one step in the production of charcoal. Harvesting and transportation of the raw material and the distribution of the finished product are also of great importance. These processes have also been rationalized and modernized by the Katugo scheme. Bow saws, power saws, and sledge hammers have been introduced to replace more arduous methods. Mechanized transportation of the wood to the kiln also helps accelerate the pace of the production process. Constant productivity ensures daily delivery to markets: supply now equals demand. By-products that were previously wasted, or "fines", have now found an application in a briquetting machine designed for small-scale industry.
The new method has had a number of beneficial effects on local inhabitants. It has led to the development of skills in the local work-force, which has received training in the use and maintenance of modern hand tools. Personnel at all levels have been instructed in aspects of construction and maintenance of the kilns, receiving full training in kilning techniques. As a result, a skilled work-force has been created with greater future employment opportunities.
The results of a survey on use of the new kiln method were strongly in favour of permanent charcoal kilns, principally for creation of employment in rural areas. Increased prosperity and employment prospects attract the inhabitants of neighbouring districts, and educational and medical facilities receive more emphasis. Local markets for agricultural produce expand, in turn increasing the general level of prosperity. In more abstract terms, the importance of contributing to the country's store of technical know-how is not to be underestimated.
The Katugo method has been introduced throughout Uganda and, as a result, many large-scale commercial kilns have been constructed. Many small industries have adopted the Katugo design and technology and now, with the assistance of experts, provide practical training programmes for employees. The Katugo design may also have wider-ranging application and importance: the Ugandan Forest Department is now prepared to provide the relevant technical detail to other developing countries.
A. C. Kawanguzi with Patricia Merrikim