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< prev - next > Energy Biofuel and biomass KnO 100138_Charcoal production (Printable PDF)
Charcoal is widely used as a domestic fuel for cooking in
many towns and cities in developing countries as it is
cleaner and easier to use than wood.
Small-scale charcoal production is labour-intensive. It
can be divided into different stages of operation.
Growing the fuel
Harvesting the wood
Drying and preparing the wood for
Carbonising the wood to charcoal
Screening, storage and transport to
warehouse or distribution point
However, it can have a detrimental effect on the
surrounding environment when demand for fuel increases
beyond what can be supplied on a sustainable basis.
The amount of charcoal produced varies, with the methods
employed to produce it, and the skill of the operator.
This brief looks at some of the approaches in the
production of charcoal and on a small scale in developing
Figure 1: Charcoal production. Photo:
Practical Action Sudan.
counters where efficiencies can be greatly improved through the adoption of better techniques and
Although wood is the most common fuel source many other sources have been tried including
agricultural waste such as millet stems and corn cobs as well as coconut shell. These biomass
materials are made up of cellulose, lignine and volatile substances and water. During the production
process the volatile components are driven off and the cellulose and lignine are decomposed. The
process is divided into the following stages.
Combustion: oxygen supply is high and temperature rises from ambient to over 500°C and
when the fire is established, the oxygen supply is reduced after the firing point is closed and
temperature drops to about 120°C.
Dehydration: free water is driven out at a reduced temperature of about 100°C and the kiln
gives out thick, white and moist steam.
Exothermic reaction: when the wood has dried, temperatures rise to about 280°C and the
wood begins to break down into charcoal, water vapour and other chemicals; the smoke at
this stage is yellow, hot and oily and the temperature is maintained by controlling the air
flow through holes and vents to help burn more wood.
Cooling: when carbonisation is complete, the kiln cools to below 100°C and charcoal can be
removed for further cooling.
The process of carbonisation is greatly dependent on the carbonisation temperature, the moisture
content of the wood used (the drier the better), the skill of the producer and the condition of the
wood (lignin content).
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