Fuel from the Fields: Charcoal from agricultural waste
Practical Action
The holes in the oil drum may be cut with either a hammer and chisel, or an angle grinder.
• Do not use an angle grinder or any other tool that will create sparks unless it is certain
that there are no flammable or explosive residues inside the oil drum.
• The drum should not contain any toxic or explosive residues.
• If it has safe residue (oil or food) a small fire should be made inside the drum to clean it
out. Allow the drum to cool before starting to cut holes.
• Both flat ends of the drum must be intact. The drum cannot be used if one entire flat
side has been cut off.
• There must be no holes in the curved sides of the drum.
The loading hole (figure 4) in the top of the drum may be round or square. The edges of the
loading hole should be at least 8cm from the edge of the drum, providing enough space for the lid
to rest on. The empty drum will be easier to move if the edges of the loading hole are not rough
and jagged so people can lift the drum more easily.
Cut about 9 small air holes (figure 5) in the bottom of the
drum to allow for air to flow through it, making a hotter
initial fire. The air holes should be evenly distributed and
roughly 8cm apart. One air hole should be near the centre.
They can be any shape, but no more than about 8cm in
diameter, to stop material falling through the holes.
Figure 4: The square loading hole
in the top of the drum. Photo
credit: Fuel from the Fields.
The cover
You need a lid, to cover the large loading hole in the top of
the oil drum. The lid should be large enough to cover the
loading hole in the oil drum, (figure 2) but small enough
not to extend over the edges of the oil drum. An ideal lid is
made from a piece of sheet metal. It is easier to place the
lid on top of the hot kiln if a handle is welded onto the lid.
Figure 5: 9 small air holes in the
bottom of the drum. Photo credit:
Fuel from the Fields.
If you can’t make a curved handle, a handle shaped like a
short, flat ‘T’ has worked well. You can also use metal without a handle.
The briquette press
This is a small impact press used to make briquettes from the charcoal powder. The press can be
round or square and can be easily manufactured by any car mechanic or local blacksmith, if they
can weld metal. A round press can be manufactured using metal pipes; a square press, using
angle iron and sheet metal.
The outside diameter of the cup does not have to be exact; the larger the cup, the larger the
briquettes produced. The preferred size of briquettes varies in different countries. Presses made
by Fuel from the Fields range from around 5 to 10 cm in cup diameter.
The press is made up of four parts: the cup, the ejector, the plunger, and the hammering station
(a block is shown here) (figure 6).
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