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Comparing forestry wood species for the charcoal supply of Antananarivo city, Madagascar
[top] [end]IntroductionThe city of Antananarivo city relies on charcoal from eucalyptus trees (eucalyptus robusta) for its energy supplies. However, undue pressure on these trees has caused degradation of the eucalyptus plantations, and research has been done to find other suitable sources of charcoal.The study compared the energy output seven local species: Harungana madagascariensis, Leucaena leucocephala, Melia azedarach, Tephrosia vogelii, Acacia mangium, Acacia dealbata, Pinus kesiya. It also looked at the emissions, especially of greenhouse gases, which were produced in producing and using the charcoal. [top] [end]Carbonization processFigure 1 shows the temperatures to which the wood was subjected to produce charcoal during several tests.The results were analysed for quantities of ash, greenhouse gases and carbon. All the output gases were collected in order to assess the quantity of greenhouse gases produced per kilogram of charcoal.
[top] [end]Energy output testsThe purpose of these tests was to compare how different charcoals would behave in actual households using an improved stove.A stove was enclosed in a container from which a chimney carried the exhaust gases past a set of laboratory measuring instruments (see Figure 2). Each sample of charcoal was lit using ethanol and a fixed quantity of water was brought to the boil and boiled for 30 minutes. For each phase - ignition, bringing to the boil, and boiling -the weight of charcoal used and the quantity of water which evaporated was measured, as well as the time needed to bring the sample to boiling point. Throughout the test, the temperatures of the fireplace, the water and the chimney were recorded continuously, and the volume of gases emitted was recorded.
[top] [end]ResultsTwo charcoal samples were produced from each type of wood. Four stove tests were performed for each charcoal type. Table 1 presents the average results. It can be seen that charcoal yields were between 31% and 37% and volatile gases were between 20% and 25%. The only major difference between the woods tested and eucalyptus was the low heat output rate when charcoal made from leucaena was used.[top] [end]Conclusions[top] [end]Greenhouse gas productionCompared to eucalyptus, the emissions resulting from charcoal-making and in cooking turned out to be very similar for 3 of the woods; the four other species produced less greenhouse gases. The quality of the charcoal did not appear to affect the quantity of greenhouse gas emissions very much, although the poorer quality charcoal yielded slightly less greenhouse gases.[top] [end]Charcoal usabilityThe studied varieties of wood have been classified by density, charcoal quality produced and performance in cooking, and their overall performance graded on a 0-7 scale. This is shown in Figure 3.
[top] [end]Overall conclusionsNone of the factors alone can provide the ideal choice. However, using the criteria described above, the following woods appear to be the most favourable:Acacia mangium, Pinus kesiya, Tephrosia vogelii. These results show that, where choice of fuel is available, an integrated approach provides a useful tool in selecting suitable woods to grow for charcoal production for household energy. Table 1: Charcoal production and stove test results
(a) kg equivalent CO2 / kg of charcoal [top] [end]Contents: Boiling Point 40: Household energy and health
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Page created:
02 August 2007; Last edited:
02 August 2007; Version: 0 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Pagename: ComparingForestryWoodSpeciesForTheCharcoalSupplyOfAntananarivoCityMadagascar @HEDON: BFGA | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
