Fuel from the Fields: Charcoal from agricultural waste
Practical Action
Crushing the material
The carbonised material must be crushed into a fine powder; this allows high quality briquettes to
be made.
This step can throw up a lot of fine charcoal dust. Care must be taken to use airtight bags, and to
avoid breathing in the charcoal dust. Sprinkling water on the carbonised material can reduce the
dust.
• Fill rice bags, or some other airtight bag, with the charcoal. Sprinkle some water inside
the rice bags, to minimize any dust.
• Seal the bags to stop any dust or charcoal powder escaping.
• Crush the carbonised material inside the bags, to make charcoal powder. Note that
carbonised bagasse is relatively soft, and easy to crush by hand. Carbonised corn cobs,
however, are much harder to crush by hand, and may need to be stamped on, or crushed
using a stone.
A number of alternative methods for crushing the carbonised material exist, including using a
large pestle and mortar (similar to those used to make fufu in Ghana).
Preparing the binder
Once you have a fine charcoal powder, binder must be added to it. This holds the powder
together, and makes strong briquettes. A number of different binders can be used; we describe
using cassava root to make a porridge, but any starchy porridge is ideal.
• Peel and grate one large cassava root for each batch of charcoal.
• Mix it with hot water, to form a thick, gummy porridge.
Approximately 1 cassava root and 1.5 litres of hot water are required to make enough porridge for one
drum of charcoal.
• Mix the fine charcoal powder, with this warm porridge, in a basin. Mix it well so that all of
the charcoal has some porridge on it.
You can test if the charcoal mixture is ready for
briquetting with your hands. Grab a handful of charcoal
powder, and crush it in your palm to make a rough
ball. If the ball falls apart when you let go, the
charcoal needs more binder. If the ball keeps the
shape of your hand, it is ready to make briquettes.
Making the briquettes
After the binder and charcoal are well mixed together,
you can make briquettes. You need the briquette press,
and a hammer, or wooden mallet.
• Figure 3 shows the briquette press. With the
ejector resting in the bottom of the cup, scoop
up a full cup of charcoal powder.
• Place the plunger in the cup.
• Hit the piston hard with the hammer 3-5
times, to compress the powder (figure 16).
Figure 16: Using the briquette press
Photo credit: Fuel from the Fields.
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