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Kisangani Smith Group / Blacksmiths develop wood-saving stoves

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In Tanzania, rural blacksmiths use charcoal to run their furnaces, and this is a major contributor to deforestation.

A group of blacksmiths set up the Kisangani Smith Group (KSG) to pass on their skills to unemployed young people. KSG is tackling deforestation by developing more efficient stoves and planting trees to provide the charcoal for their furnaces.

With 3 years, 1,400 sawdust and 2,100 wood stoves were manufactured and sold...

... benefiting at least 17,000 people

 142 blacksmiths trained by KSG

"I like everything about my sawdust stove – it saves time, it saves money and it looks good."

Mama Kaduma, entrepreneur, Njombe


Njombe is a small but important town near the Southern Highlands of Tanzania. Although there is a range of employment opportunities in the town and surrounding region, including working in the large tea and timber industries and making furniture, young people have difficulty finding jobs. The region has significant timber plantations and supplies timber to other parts of Tanzania as well as Kenya. However, there is growing pressure on wood resources, partly as a result of the extensive use of charcoal for cooking in the towns. Wood is the main cooking fuel in rural areas, where most people cook on traditional three-stone stoves.

The Kisangani Smith Group (KSG) saw potential for replacing fuelwood with sawdust, which is generated by the timber and furniture industries and usually discarded and left to rot in the centre of Njombe and elsewhere in the region. The group therefore focused its efforts on developing and fabricating an efficient sawdust-burning stove, which could be made by local blacksmiths.

Furaha Haule and son using sawdust stove

The organisation

KSG was established as a non-profit organisation in 1996 by a group of volunteer blacksmiths, with a mission to alleviate poverty through appropriate technology. KSG started by training unemployed young people in metal working skills, so that they could make and sell agricultural and workshop tools. This work required charcoal to fire small furnaces, which the group realised was contributing to deforestation, so KSG started planting trees. Developing more fuel-efficient cooking stoves was a logical next step for the organisation.

KSG formally registered as an NGO in 2002, and by 2009 had 25 members. Most finance has come from small grants, and support from the Small Industries Development Association and the local Government has enabled participation at trade fairs. In 2006, KSG annual turnover was approximately US$60,000.

Most KSG members are based at the main workshop in Njombe, but some are at the three smaller village workshops. KSG has been given permission to use land in the hills around Mkiu/Kiyombo village for tree planting, which will eventually provide a sustainable source of wood and a sustainable income. In return, KSG is helping the village to develop a hydro-power scheme, which will bring electricity to three villages, and the KSG village workshop.

KSG machine work

The technology

How does it work?

KSG has developed two types of portable stove to replace traditional three-stone fires and charcoal stoves. The first uses sawdust as fuel, but rice husks and other agricultural residues can also be used. The second is an improved wood-burning design.

The sawdust stove is cylindrical, with feet to raise it off the ground. The lid of the stove has a heat-spreader and pot support, and at one side an entry port at the base serves as the air inlet. This inlet also allows a small amount of wood to be introduced, which is useful for getting the stove started and sometimes for controlling the burn rate as well.

Prior to use, the stove is filled with sawdust. When lit, the sawdust gradually burns away at the bottom and chars at the top. One load of sawdust can burn slowly for up to six hours, so that several pots of food can be cooked and water for washing heated at the end. Expected stove life is three to five years: some early prototypes have been in use for five years.

Sawdust stove after about 10 minutes

The wood stove looks similar to the sawdust stove on the outside. An entry port at the base serves as the air inlet. The lid has a pot stand, but a less complex heat spreader. Once the metal body and entry port have been made, the floor of the stove is covered with clay. Insulating bricks are fitted around the sides which helps to form an internal chimney and direct the combustion gases towards the hole in the centre of the lid.

How much does it cost and how do users pay?

US$1 = 1100 Tanzanian Shillings (TSh) [April 2008]

The retail price of the sawdust stove is about US$32 (35,000 TSh) and the wood stove US$27 (30,000 TSh). Stoves are sold mainly through retailers, who place bulk orders with KSG at trade fairs and are given a small discount on the price. Purchasers pay for their stoves in full in cash: no credit system is offered by KSG.

How is it manufactured, promoted and maintained?

Stoves are made in the main KSG workshop in Njombe, and nearly all the manufacture is done by hand – the only electric tools used are drills and a spot welder. A complete stove can be made by one blacksmith in three to four hours, although normally a number of blacksmiths will work on a batch of stoves, each working on one part of the process.

Cooking on a stove made by KSG

New users receive an instruction leaflet explaining how to use their stove. KSG has held training sessions, but owners find them easy to use even without formal training. The heat spreader on the sawdust stove is the part that sometimes fails, prompting retailers to ask KSG for replacements. KSG supplies new parts or the materials for a local blacksmith to make them.


Between 2005 and 2008, KSG and its trainees manufactured and supplied approximately 3,500 stoves (1,400 burning sawdust and 2,100 wood), benefiting at least 17,000 people.

Environmental benefits

Based on approximate measurements carried out by KSG, about 24 m3/year of fuelwood is used for an open fire, compared to 6 m3/year for the wood stove and 2 m3/year for the sawdust stove. The wood and charcoal savings made as a result of using the more efficient stoves thus contribute to reducing deforestation and greenhouse gas emissions. However, the extent of this benefit is difficult to quantify, because of the uncertainty in overall wood savings, and also limited information on the sustainability of supply.

I got headaches and breathing problems when I cooked on an open fire or a charcoal stove, but they have stopped with the new wood stove.

Mrs Mpete, Primary School Teacher

Social benefits

The sawdust stove saves time, because there is no need to collect fuelwood and because food cooks much more quickly. In addition, once the stove has been filled and lit, it can be safely left virtually unattended, whereas a wood stove or charcoal stove needs frequent checking and re-fuelling. The stove will continue producing heat for six hours or more, before it needs to be refilled, and most people fill the stove only once or twice per day. Women also report less eye irritation and fewer respiratory problems with the new stove.

The wood stove becomes hot more quickly than an open fire, so it is now possible to prepare hot food and hot drinks in the morning as well as the evening.

Economic and employment benefits

Most sawdust stoves have been purchased by householders for cooking family meals. The main motivation to buy such a stove is to save the cost of charcoal. A family cooking with charcoal typically uses about 140 kg of charcoal (two standard sacks) costing US$9 (10,000 TSh) per month, and sawdust replaces virtually all this use. Because the sawdust is free, it only takes three to four months to repay the cost of the stove through savings in charcoal. Café owners report that they save about four to six sacks of charcoal per month, worth US$18 to US$27 (20,000 to 30,000 TSh), so for them the stove pays for itself within two months.

About 120 smiths have been trained by KSG over the past ten years. Some of these now have businesses and employ other staff as well.

Sawing trees in forest – another source of sawdust

Potential for growth and replication

There is significant potential for replication of the KSG sawdust stoves. Any competent blacksmith in Tanzania or elsewhere could produce a set of templates to the KSG pattern, and start producing stoves. The stove could be used anywhere that has access to a good supply of sawdust, or other agricultural residues. The wood stove is similar to other designs, but still has potential for replication given its simplicity of manufacture.

Update: what happened next?

By 2009, 4,620 stoves (2,220 burning sawdust and 2,400 wood) had been produced by KSG. The wood and sawdust cooking stoves and heating systems have been improved and a new larger sawdust stove has been developed for institutional use, with three installed to date. The tree planting programme continues each year. 142 blacksmiths have now been trained by KSG since the programme began.

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