Biomass
Practical Action
Figure 4: Improved Charcoal Kiln found in Brazil, Sudan and Malawi.
Pro-Natura has developed a process based on the continuous carbonisation of renewable
biomass, savannah weeds, reeds, straw of wheat or rice, cotton and corn stems, rice or coffee
husk and bamboo to produce green charcoal.
Briquetting
Briquetting is carried out on many materials to make them more suitable to be used as an
energy source. Nearly all biomass has the potential to be briquetted into a hard stable fuel that
has a high energy density and provide more consistent combustion and improved storage and
transportation.
The important factures in making briquette are the ash content or non combustible components
and the moisture content. The raw materials that are commonly made into briquettes and pellets
include:
Wood & Sawdust
Biomass waste such as rice husk, cotton stalks etc.
Bagasse fro sugar cane
Although briquetting is often a large scale commercial activity most waste biomass can be used
as a fuel source either by directly briquetting or through the production of charcoal that is then
briquetted on a small scale. Binders used for direct briquetting include starch paste, cellulose
from woody material, cowdung and clay, which can be extruded of formed by hand into balls.
One example of briquetting sawdust with a binding agent in Malaysia first carbonised the
sawdust then uses starch as a binder. The starch paste is made in a separate cooking tank.
Charcoal = 73%
Starch = 5%
Calcium carbonate = 2%
Water = 20%.
These charcoal briquettes can be made with a low-pressure mould.
Research by Chardust Ltd
Into making charcoal briquettes from various crop wastes including sisal waste. One report
concluded that carbonising sisal was technically quite difficult in respect to regulating the
temperature resulting in non-homogenous carbonisation but once the sisal waste had been
carbonised it was relatively easy to produce briquettes. These were made by producing a paste of
carbon dust and water which is then combined with 15% clay.
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