Biomass
Practical Action
which require large pots and vigorous stirring. Fuel type can differ greatly; in some countries
cow dung is used as a common fuel source, particularly where wood is scarce. Cost is also a
major factor among low-income groups. Failing to identify these key socio-economic issues will
ensure that a stove programme will fail. The function of an improved stove is not merely to save
fuel.
Local manufacture of stoves
Since 1982, the Kenya Ceramic Jiko (KCJ), an improved charcoal-burning stove aimed at the
urban market has been developed and manufactured by large numbers of small producers. The
KCJ has two main components; metal and fired clay. Both these parts are made by
entrepreneurs; the metal part (cladding) being made by small-scale enterprises or individual
artisans, while the clay part (liner) is manufactured by slightly larger and more organised
enterprises or women’s groups. The KCJ is sold by the artisans directly to their customers or
through commercial outlets such as retail shops and supermarkets. The stove was initially
promoted heavily to develop the market, by the NGO KENGO and by the Kenyan Ministry of
Energy, through the mass media, market demonstrations and trade fairs.
As a result of this substantial promotion, there are now more than 200 artisans and micro-
enterprises manufacturing some 13,600 improved stoves every month. To date, it is estimated
that there are some 700,000 such stoves in use in Kenyan households. This represents a
penetration of 16.8% of all households in Kenya, and 56% of all urban households in the
country.
Source: Dominic Walubengo, Stove Images, 1995
Charcoal production
Charcoal production is the most common
methods for processing wood to make
them cleaner and easier to use as well as
easier to transport but charcoal does not
increase the total energy content of the
fuel - in fact the energy content is
decreased. Charcoal is often produced
in rural areas and transported for use in
urban areas.
The process can be described by
considering the combustion process
discussed above. The wood is heated in
the absence of sufficient oxygen which
means that full combustion does not
occur. This allows pyrolysis to take place,
driving off the volatile gases and leaving
charcoal (carbon). The removal of the
moisture means that the charcoal has a
much higher specific energy content
than wood.
Figure 3: Charcoal Kilns, Malawi. Photo: Practical
Action / Paul Harris.
Other biomass residues such as millet stems or corncobs can also be converted to charcoal.
Charcoal is produced in a kiln or pit. A typical traditional earth kiln will comprise of the fuel to
be carbonised, which is stacked in a pile and covered with a layer of leaves and earth. Once the
combustion process is underway the kiln is sealed, and then only once process is complete and
cooling has taken place can the charcoal be removed.
A simple improvement to the traditional kiln is also shown in Figure 5. A chimney and air ducts
have been introduced which allow for a sophisticated gas and heat circulation system and with
very little capital investment a significant increase in yield is achieved.
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