Production of charcoal briquettes from cotton stalk in malawi: methodology for feasibility studies using experiences in Sudan

摘要

The feasibility of charcoal production from cotton stalks in Malawi was studied based on experience from Sudan. The country relies considerably on biomass fuels. Of the total energy consumption in Malawi of 2.376 MTOE in 1989, 92% was met by biomass (fuelwood: 83.6% and charcoal: 8.3% Petroleum fuels and ethanol contributed 5.4%; electricity, 1.6%; and coal, 1.0%. Most of the energy (84.8%) was consumed in the household sector. The “Malawi Charcoal Project”, which is the main charcoal project carried out in the country, attempted to produce alternative softwood charcoal from the large resource of pine plantations but was not successful because of unacceptability of the product for household use, long transport distances and costs, and the equipment required for industrial uses. Briquetting of uncarbonized sawdust was also carried out by the Wood Industries Corporation (WICO), but failed due to unacceptability of the products and technical problems. The estimated total national demand for cotton stalk charcoal (CSC) briquettes is 15,000 t yr−1 made up of 7000 and 8000 t yr−1 for household and industrial sectors, respectively. The household demand is most substantial in Blantyre (3500 t yr−1) and Lilongwe (2700). t yr−1 Ngabu town was found to be the most appropriate location for a plant to supply the Blantyre market. Of the many plant options that were found financially and economically viable, four, using drum kilns for carbonization, were the most attractive. These were the 800 t yr−1 agglomeration process with seasonal sun drying operation, 2- and 3-shifts, and the 3000 t yr−1 roll process, year round operation, 2- and 3-shifts with financial internal rates of return of 28.1%, 38.3%, 26.6% and 40.0% respectively and a pay-back period of three years. The agglomeration process was overall the most attractive, though not significantly so financially.