|Low Cost Charcoal Gasifiers for Rural Energy Supply (GTZ, 1994, 49 p.)|
Rural areas in developing countries are commonly characterized by disperse population and a lack of infrastructure. Especially the electric grid, a symbol for industrialization and high living standard, is missing and is extremely unlikely to be installed even in medium terms of energy planning due to the large distances and the low level of industrialization. On the other hand, energy supply is a basic condition for improved living conditions and increased productivity.
Especially important is the energy supply in agriculture, for example for irrigation pumps and the various machinery for post-harvesting, including grain mills. Small scale processing machinery (small saw mills, metal workshops) are another option, and last not least it is electricity for domestic use (light, radio, television). All that can be covered by "gensets" (the combination of a combustion engine and an electric generator) of 3-20 HP (2-15 kW) shaft power, and this is exactly the power range for"small gasifier-engine-systems". Such gasifier systems do not consume excessive amounts of fuel: If firewood is available at sufficient amounts, a gasifier for village energy supply should not present a problem of fuel shortage. Even the use of charcoal as fuel is acceptable for small gasifiers. Of course, energy losses are a consequence of charcoal production. But, on the other hand, charcoal is an excellent gasifier fuel, it avoids tar formation in the gasification process, and the sizing of the fuel particles is much easier than the respective cutting of wood. At the present state of the art, the use of charcoal as fuel is highly recommendable, if gasifier-engine-systems around or below 10 kW shaftpower are to be applied.
Two International Conferences on Producer Gas, held 1982 in Sri Lanka and 1985 in Indonesia focussed on this topic, and a substantial amount of research and development was presented at these occasions. Then, gradually, the interest faded away. That happened when the state of the art was apparently not too far away from a level, sufficient to render technically viable results. That was the point when a joint project of the
German Ministry for Research and Development (BMFT), the German Agency for Technical Cooperation (GTZ) and the University of Bremen started. The aim of the project CHAR (CHARcoal gasifier), carried out by the "Forschungslabor frgie- und Umweltschutzsysteme (FLEUS)" at the University of Bremen, was the development of a reliable and cheap charcoal gasifier in the power range of 2-10 kW, based on an evaluation of the existing international experience with such systems. Parallel to this project, GTZ ordered a set of studies concerning non-technical aspects of gasifier application, such as problems with handling and maintenance of gasifiers under field conditions as well as reports about existing dissemination programmes in selected countries (see [3 - 8]).
As the project started at a time when it was already obvious that the existing gasifier systems did not meet the expectations, the search for reasons for the limited success was the first step to define further research activities.