We have discovered that dry waste biomass can be burnt in a simple container (like a bucket) provided a vertical air hole is made through the sawdust.
In most developing countries there are vast amounts of waste biomass which are unused and twigs and branches are burnt instead. Among this biomass is sawdust, rice husks, coconut shells, etc
A video of a Tanzanian simple sawdust stove being made can be seen at www.youtube.com/watch?v=fIlOamR9wAg
We have shown how a stove can be made very simple and cheap. A Nigerian, Clem, has made several simple stoves and proved how sawdust is an excellent as well as a very cheap fuel as well as other waste biomass.
We have shown how the basic design can be modified to deal with some other dry waste biomass and next we will move to making Biochar as well as heat.
Above is photo of a simple sawdust stove being tested in Cameroon by WIDCO!
Simple Biomass (Bucket) Stoves
It has been shown that it is easy to burn sawdust using a very simple stove.
We are hoping that this solution will spread to wherever dry waste biomass is available and especially in the poorest parts of the world.
It seems that years ago this simple design of stove was in use in many places but then went out of favour. This was probably due to the fact that wood-burning/pellet stoves were more convenient in regulating the cooking heat, even if not fuel efficient.
Obviously, when using waste sawdust, cookers/stoves are usually much cheaper to run!
Another more recent reason to ignore this simple stove is from concerns about climate change and the need to make charcoal (used for biochar) but this is more complicated.
We are trying to re-introduce the simple cooker, as is being done in Tanzania and Cape Verde, see videos http://www.youtube.com/watch?v=fIlOamR9wAg &
but also spreading its use to other waste biomass as well as with more complex stoves
needed to also make charcoal.
Although best made from sheet steel it is quite possible to make a sawdust stove using clay bricks or fired clay.
This type of stove relies on the 'stickiness' of sawdust to allow an air hole to penetrate through the body of sawdust. Most sawdust, even when quite dry, allows this hole to be made. We understand that groundnut shells can also be used in this way.
Rice husks are another possibility having now been tested by Clem.
However we intend to improve the design and produce a BioDesign stove version that allows even powdery/flowing dry biomass to be burnt in a similar way.
Comparison with other biomass stoves
Most stoves allow some form of fuel-control but the simple sawdust type has only a little. More info later.
When debating with biomass stove enthusiasts (often Westerners) we often find that their aim is different to ours.
They concentrate so much on stove burning efficiency or smoke reduction that the stove design becomes quite expensive and thus often unaffordable, except when financed.
In fact the evidence seems to be that most sawdust stoves produce less smoke than wood-burners but, even where not, being much cheaper it might permit a chimney to be built.
Although most of our efforts are directed at products that can be made by the poor there are NGOs serving them that are looking for ways to generate funds and making commercial sawdust stoves is one possibility.
There is no reason, for example, why an enterprise could not also make sawdust 'pods' that could be a packet ready-filled with sawdust and paper tinder that could be dropped into a stove instead of having to fill it by hand and make the air hole!
It might also be possible to have two 'parcels' of biomass fuel allowing the lighting of one and then later the other!
Clem's & GK's first reports
If you wish to know more about our first efforts with waste biomass do ask.
A leaflet on producing stoves for different biomass is also available.
Biomass stoves in Tanzania
This stove burns sawdust, which is readily available as waste from the timber and furniture industry in
Njombe. Elsewhere in Tanzania it is also used with rice husks and other agricultural
residues. When filled with packed sawdust, the stove can burn steadily for up to six
hours. Users like the stove because it cooks quickly and cleanly, needs little attention,
and above all saves money. A stove costing 35,000 TSh (£16) can save a family over
10,000 TSh (£4.50) per month
Our simple stove costs far less!