Fuel from the Fields: Charcoal from agricultural waste
Practical Action
The agricultural waste will slowly
carbonise inside the hot oil drum. After
2-3 hours, when you are sure that the
drum has cooled, you can remove the
lid.
Before removing the material, sprinkle
some water inside the oil drum. This will
reduce the amount of charcoal dust that
is thrown up into the air.
Figure 13: Gently lower the drum to seal off the air holes
on the bottom. Photo credit: Fuel from the Fields.
Charcoal
After 2-3 hours, the material inside the drum should be fully carbonised (figure 14). This means the
charcoal powder will be black throughout. If corn cobs are used; the cobs will be brittle and easy to break;
the centre of the cobs will also be black.
If the drum was allowed to burn for too long before
sealing, the yield may be low. In this instance, a lot of
material will have burned away, and grey ash will remain.
If, by contrast, the drum was not allowed to burn for
long enough, or some parts of the drum did not get hot
enough, the material will not be completely carbonised
(figure 15). If using cobs, they will still have a white
core; bagasse may still be brown coloured.
Uncarbonised material does not make good briquettes.
• Sort any uncarbonised material, and put it to
one side. It can be used when filling the drum
for the next batch, to avoid waste.
Figure 14: Fully carbonised corn cobs. Photo
credit: Fuel from the Fields.
Figure 15: Corn cobs that are not
completely carbonised. Photo credit: Fuel from
the Fields.
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