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Residue Utilization - A recent example from Africa by Josef Leitman
[top] [end]Ethiopia: Agricultural residue briquettes as a household and industrial fuelAgricultural residues from small farms are currently being used as a fuelwood substitute throughout Ethiopia. At least 3,300,000 metric tons of surplus coffee, cotton, wheat and maize residues are produced annually, although not all are economically accessible. Concentrated quantities are found on Slate-owned farms and processing facilities where excess residues are accessible and form a potential fuel source. This unused surplus amounts to a conservatively estimated potential of nearly 600,000 tons, which is equivalent to over 640,000 tons of fuelwood, or around 50% of annual household fuel demand in Addis Ababa.A sizeable market for densified agricultural residues exists, given the current household and industrial demand and pricing structure. In the household sector, firewood, animal dung, crop residues and charcoal accounted for 99% of fuel consumption, or 22 million tons of wood equivalent (TWE) in 1982. By 1992, this is expected to climb to 29 million TWE, of which 22 million TWE will represent a deficit beyond sustainable supply. In the target household market (the Addis Ababa pert-urban area), the biomass fuel deficit will be 940,000 TWE, or 747,000 tons of densified residues. In the industrial sector, total energy consumption - or process heat is equivalent to a potential demand for 338,000 tons of densified residues. However, 224,000 tons technicaly substituted for other capital investments. Cotton stalk briquettes can be produced for $82 per tonne; with an additional $32/tonne to cover transportation, they have a delivered priced in Addis Ababa of $114/tonne. On a useful energy basis for households, the cost of cotton stalk briquettes is $25.40/GJ.
The World Bank is now financing several pilot projects to produce agricultural residue briquettes from coffee, cotton stalk, wheat straw and maize residues, in that order of priority. The $6 million project entails collection, processing, densification, packaging, storage, transportation, marketing and distribution. In financial terms, all of the proposed briquetting plants produce a competitive household fuel priced at less than half the useful energy cost of charcoal. When fuelwood is taken as the comparator, then the coffee residues currently have a lower useful energy cost, with the other residues becoming competitive in the near future (see Fig. l). In economic terms, all types of briquettes have a much lower cost of useful energy than kerosine, which is the comparative fuel with guaranteed availability. For industrial use, residue briquettes can be produced and delivered to users in Addis Ababa at a lower cost than most industrial fuels (fuel oil, fuelwood charcoal and electricity). Economically, cotton and maize briquettes are more expensive than fuel oil but less than the other fuels. Thus, agricultural residue briquettes are a viable economic alternative to increasingly scarce and costly fuelwood for both domestic and industrial fuel. Most agricultural residues can be used as a fuewood substitute in loose form. However for reasons relating to transport, storage, marketing and cookstove or industrial boiler design, residue use can be enhanced and expanded through densification. For example, the cost of straw to the capital from 300 km away would be a prohibitive USS 144/ton while transportation charges for a ton of wheat straw briquettes would be only $45. The abi1ity to produce a marketable, densified fuel depends on the densification technology, chemical composition of the residues, their burning characteristics, delivering baled wheat social/technical acceptability and their selling price. Regarding choice of technology, high-pressure briquetting results in a densified fuel with physical caracteristics that are quite similar to xeisting domestic fuels and can also substitute for solid or liquid fuels in pilers with - little or no equipment modification in many cases. [top] [end]ConclusionSMAP and the World Bank Energy Department are currently evaluating biomass energy projects in a number of African and other developing countries. Information was drawn from the following ESMAP reports:Ethiopia: Agricultural Residue Briquetting Pilot Projects for Substitute Household and Industrial Fuels, Report No. 062A/86, ESMAP, December 1986. Cote d'Ivoire: Improved Biomass Utilization - Pilot Projects using Agro-Industrial Residues for the Energy Sector, ESMAP, April 1987. Mauritius: Bagasse power Potential, 1987-2000, ESMAP May 1987.
[top] [end]Editorial commentLeitmann's article deals with the use of agricultural residues for industrial or electricity generation purposes rather than or the village housewife. It estimates a 1992 Ethiopian domestic fuel shortage of 22m (TWE) and proposes to take residues from round the country to meet the Addis Ababa for age of lm (TWE) presumably because of the ease of marketing and the ability of people to pay higher prices - or perhaps it will be bought by industry. The provincial areas will have 1m (TWE) less fuel available for their kitchens.The World Banks's $6m project in Ethiopia will establish large centres for briquette production to which residues will be-transported. Use as a fuel in villages and small towns would involve further transport in Ethiopia's inadequate roads and would result in a selling price beyond the reach in the poor rural housewife. The alternative, of small, low cost briquetting using locally available materials and employing and supplying local people does appear to have been investigated by the Bank. [top] [end]Contents: Boiling Point 12: Alternative Fuels - One way to reduce woodfuel demand
Categories: Boiling Point 12| Fuels| Briquettes| Agricultural Residues| Pellet| Improved Stoves| Africa| World Bank | ||||||||||||
Page created:
17 September 2008; Last edited:
22 September 2008; Version: 0 | ||||||||||||
Pagename: BP12:ResidueUtilization-ARecentExampleFromAfrica @HEDON: QRNA | ||||||||||||
