Charcoal from prosopis:

Provisional study report

Abdi Zeila* and Bashir Jama

The Centre for Sustainable Development Initiatives (CSDI)

PO Box 16109 – 00100 Nairobi, Kenya

www.csdikenya.org

September 2005

*Corresponding author: azeila@csdikenya.org

Acknowledgements

We would like to gratefully acknowledge the technical and material help we have received from the Kenya Forestry Research Institute’s Karura Forest Products Resource Centre, and specifically from the Centre Director Mr Githiomi, and Ms. Nellie Oduor. We also thank Mr James Kimwemwe of KEFRI Karura who assisted with setting up the kilns in the districts as well as in training the charcoal producers in the Casamance charcoaling system in the districts.

We also acknowledge the tremendous support from the Arid Land Resource Management Project II (ALRMP II) staff in all the districts, led by the respective Drought Management Officers – Mr. Julius Taigong (Baringo), Mr. Jerald Bombe (Tana River) and Mr. Yassin Farah (Garissa). We also wish to thank sincerely the 22 charcoal burners who were involved in the study across the three districts.

Abdi Zeila and Bashir Jama

September 2005

Table of contents

Acknowledgements. 3

1.0 Executive summary. 5

2.0 The objectives. 7

3.0 The sites. 8

4.0 Description of the kilns. 9

4.1 The Casamance kiln. 9

4.2 Traditional earth kiln. 9

5.0 Methodology. 11

6.0 Some provisional results. 13

6.1 Casamance kiln. 13

6.2 Traditional earth kiln. 13

7.0 Discussion of the results and some emerging issues. 15

7.1 Training of charcoal producers. 15

7.2 Policy implications. 16

7.3 Follow-up issues. 18

8.0 References. 19

1.0 Executive summary

Since the introduction in the early 1980’s of the invasive alien species Prosopis juliflora in some dryland districts of Kenya, for purposes of fuelwood provision and soil conservation, communities living in these districts have been struggling to find a way of managing the species. The plant is generally viewed negatively and many of the affected communities favour its total eradication. However, its total eradication may not be possible given its unique biological traits. Many countries, such as the United States, Australia, Sudan and South Africa, have all been trying to manage it through utilisation since its eradication is practically impossible.

One option is to use to charcoal at the level of households and institutions.  Towards this, the Centre for Sustainable Development Initiatives (CSDI) commissioned a study to determine the potential of simple and inexpensive charcoal making technologies to Garissa, Tana River and Baringo districts. The results presented here are provisional, and further tests are planned to be jointly conducted with Kenya Forestry Research Institute (KEFRI).

Charcoal is the product of the carbonization of wood, which is brought about by heating wood, in the absence of air, to temperatures sufficiently high (e.g., in the range of 400 to 500ºC) that can sustain thermal decomposition. The wood’s physical and chemical properties, its wood content, the heating rate and external pressure determine the nature of the primary decomposition products (KEFRI, 2002). However, the three major factors that influence the conversion yield are (1) the moisture content of the wood at the time of carbonization, (2) the type of carbonizing equipment used, and (3) the care with which the process is carried out.

The traditional charcoal-making technologies have one main drawback: low recovery rates. The low recovery rates are mainly due to the poor organization and structure of these kilns. As a result, these kilns generally give rates of usually between 5 and 10%, although it may be higher than this in certain localities, depending on whether the charcoal producers have modified and improved the kilns. Another factor contributing to the poor structure is that the producers are not motivated to improve their rudimentary production systems because the markets are not good or reliable enough. As will be seen in this report, markets in many of the dryland districts for charcoal produce are simply not big enough. In Tana River, for instance, the producers involved in this study were not motivated to improve their production system because Hola town residents, the biggest in the district, mainly use firewood as their prime energy source. However, the Garissa folks have good markets and were very innovative in their charcoal production technologies.

2.0 The objectives

The objectives of this study were:

• To determine the recovery rates of the Casamance mount kiln, an improved charcoal kiln technology, in the three districts
• To determine the recovery rates of the existing traditional charcoal production techniques in the three districts
• To conduct on-site training and demonstration for charcoal producers in the use and operation of the Casamance mount kiln
• Suggest possible policy changes on charcoal production, especially with respect to populated settlements such as towns and refugee camps

3.0 The sites

The sites for the study were chosen on the basis of the presence of mature prosopis trees capable of yielding considerable charcoal quantities. The other consideration was the presence of charcoal producers in the area.

In Baringo, the study was undertaken in Endau area, about four kilometres from Marigat Township. The area is almost completely covered by a thick, almost impenetrable thicket of prosopis trees. It is also traversed by dry streambeds, which in the rainy seasons, drain floodwaters from the Tugen Hills into Lake Baringo.

In Garissa, the Farmer Training Centre’s Hodhan Farm was selected as a most appropriate site because of the tall, mature prosopis trees near the edge of the River Tana. The farm, which is completely colonized by prosopis, is also host to dozens of charcoal producers.

Malindi-ya-Ngwena was selected as an appropriate site for this study in Tana River. The area, which is bordered on the east by River Tana, is about four kilometres from Hola Township and is also host to charcoal producers.

4.0 Description of the kilns

4.1 The Casamance kiln

The Casamance kiln is an improved version of the traditional earth kilns, which results in better carbonisation control and hence higher yield of better quality charcoal.  Cassamance Mould kiln

The Cassamance mould kiln is a modified earth kiln whose experiments was carried out in Senegal and gave good results.  The kiln is stacked in a circular way. First the air channel is made across the circle and thin pieces of wood arranged in a circular way leaving spaces between them for easy airflow. The base plays an important part, for it assures airflow in the mould. The largest pieces of fuel wood were placed at the centre standing upright and all medium-sized pieces around them. The stacking is done as tightly as possible filling all the gaps between with smaller fuel wood pieces to allow for better heat transfer. The kiln is then covered completely with grass and a layer of soil. At the lighting point, which is at the side opposite the chimney, small dry twigs are placed for easy lighting.

Four air inlets pipes are placed around the base of the kiln. All the smoke should be emitted from the chimney indicating that carbonization is progressing well. After around 18-24 hours, the smoke will then to light bluish in colour indicating that the charcoal is carbonized and all air inlet pipes and chimney is removed and all vents sealed completely with soil and the mould is left for two days to cool and then harvested.

4.2 Traditional earth kiln

The most commonly used charcoal processing method in Kenya is the traditional earth kiln (TEK), which has low capital requirement and can be sited near the source of wood. However, it has low conversion efficiency of about 10%. However, higher yields of up to 20% can be achieved when proper control of carbonization is followed. Some of the disadvantages of using the TEK include requirement of high levels of skill in making charcoal: inferior charcoal quality results due to lack of control over carbonization and soil contamination. The efficiency of the TEK can be improved by taking into consideration three major factors essential for good charcoaling, which include state of the fuelwood, nature of staking the kiln and regulation of air into the kiln.

 
5.0 Methodology

Dense wood was harvested and the stumps were cut low in order to gain as much wood as possible. The logs were about 0.5 m long for the Casamance kiln and 1 m long for the traditional earth kiln. The logs were then dried in a clear sunny conditions.

Two kilns, one Casamance and the other traditional kiln[1], were stacked in each of the three study sites and the average weight established using a weighing machine.

The Casamance kiln: An air channel was made across the Casamance kiln for easy air circulation during the kilning process. The stacking process was done in such a manner as to lay thin pieces of wood pointing to the centre. Spaces were left between them so as to allow uninterrupted airflow. The largest logs were left in the centre, with smaller pieces around them. The stack is then completely covered with dried grasses and leaves and soil (about 10 to 20 cm thick). The kiln was then firmly fitted with a chimney at the far end.

Air inlet holes were opened around the base and four air vents fitted in them. After putting combustible material at the mouth of the channel opposite the chimney (i.e., the ‘mouth’), the kiln was fired by igniting the centre of the mound when a burning log was inserted into the ‘mouth’. After firing, any cracks that were noticed were immediately sealed with soil. After twenty-four hours, the chimney and the air vents were removed. The kiln was then sealed completely and allowed to continue operating, but with regular monitoring.

The manpower used in setting up the stack as well as the times spent (period of carbonization) were also noted. After the kilning process was over and the charcoal had cooled, the yield is collected from the two kilns into gunny bags (can weigh up to 25 kg), which are then weighed and the weights recorded.

The traditional earth kiln: The method involved identifying suitable trees in the vicinity, choosing the kiln’s location, cutting the trees, logging them and transporting them to the kiln, gathering materials such as grass, constructing the kilns, operating the kiln, unloading the kiln and bagging the charcoal.

Stacking for the TEK was not done in any standard way across the districts[2]. A lighting zone, 1ft deep, was dug and wood placed alongside each other. Thereafter, the rest of the wood is laid perpendicular to them.

6.0 Some provisional results

6.1 Casamance kiln

Table 1: Summary of activities (Casamance kiln)

Table 2: Charcoal production data in the three districts using Casamance kilns

Note: The gunny bags were 25 kg each.

6.2 Traditional earth kiln

In our study, we established that each district has a different method of arranging the fuelwood. In Garissa, the arrangement is almost like the Casamance and is lit from the top, which enables air circulation to be uniform. This method is recommended (for the recoveries see table 3). In Tana River, they arrange their TEK in a rectangular way that they extends 3 to 4 m on the ground, hence making the carbonization time long with low yields.

Table 3: Charcoal production volumes in the three districts using traditional earth kilns

Note: Gunny bags were each 25 kg

7.0 Discussions and emerging issues

From the interim results, it is evident that using Casamance kilns generates good recovery rates, ranging between 22.6 and 25.6%,  in all the three districts (Table 2). The differences between districts are attributed to slight variations in wood handling procedures as well as differences in the quality of the wood combusted. The wood used for the test in Garissa that had the highest recovery rate was sourced from a dense tall thicket located near the River Tana, while that of Tana River district (22.6%) was obtained away from the river. It is also suggested that the sitting of the test areas might have had some impact on the weight of the charcoal generated.

From Table 3,  it is evident that the Garissa charcoal producers had the most efficient traditional charcoaling system, with recovery rates of slightly over 20%. This high rate was registered because of the proper stacking technique. In addition, the producers lighted the kiln from the top, enabling the air and heat circulation to be uniform. Tana River charcoal producers registered the lowest recovery rate (about 5%), because of the poor structure of their kilns – they arrange their kilns in a rectangular fashion that extends it 3 to 4 m on the ground, which makes the carbonization period long, and hence the low yields.

7.1 Training of charcoal producers

A total of twenty two (22) charcoal producers were trained in this study (4 in Baringo, 8 in Garissa and 10 in Tana River). The producers were highly impressed by the rates of return when they used the Casamance mount kiln compared to their traditional ones, and some started to fabricate their own chimneys while others are still using the kilns supplied to them during the study.

One issue that emerged was that the improvement of the TEK innovation was directly related to the availability of markets. Both Tana and Baringo producers were not able to access large markets for their produce. The producers reported that the demand for charcoal, as opposed to raw firewood in Tana River and Baringo, was minimal. And hence, they had little desire to innovate and improve upon their kilns. On the other hand, charcoal production is big business in Garissa because of the high demand for charcoal from the fairly town and from refugee camps in the district. As a result, many of the producers have formed informal task-based groups that look for markets and can produce between 70 and 100 bags on order in a couple of weeks.  A bag of charcoals in Garissa is sold at 120 Kenya shillings.

To improve the skills of charcoal makers, a trip to India for the ALRMP II and others from countries in the eat and central Africa region was undertaken. India has managed to tame prosopis that colonized large in its drylands through its use for charcoal and the pods as animal feed. During the trip, we managed to see some simple charcoal kilns such as the used oil drum.

Modified oil drum for charcoal production

7.2 Policy implications

At present, it is illegal to produce charcoal in Kenya although using  the same charcoal is not. Widespread charcoal production is going on in many arid and semiarid districts in Kenya. Some authorities estimate that charcoal business in Kenya has a net annual turnover of Ksh 40 billion (about US$ 520 million); the great majority of rural and urban residents use charcoal as their primary source of energy (Walubengo et al, 2005).

Garissa district is host to over one hundred thousand refugees from neighboring countries, principally Somalia and Ethiopia. These refugees, who are based in the Dadaab refugee camp, consume on average 8,500 metric tonnes of firewood annually. Since the inception of the GTZ/UNHCR programme in 1998 to supply the refugees with firewood, about 60,000 metric tonnes have been procured and distributed (Hussein, 2004). An impact monitoring team sent to assess the effect of this programme reported that clearing of woodland in Dadaab area is progressing on at the rate of 654 ha per year. Efforts at regeneration is estimated at only 51 ha, thus large areas left degraded by this phenomena.             

Informal discussions on how to address this problem have been held at district level between the Forestry Department, the National Environment Management Authority, CSDI and Terre Nova, an environmental NGO with outreach projects in Garissa. One option that has been floated is intensive lobbying of the UN and GTZ as well as community leaders on the possibility of including prosopis charcoal in the energy portfolio of the GTZ Rescue project. It has been agreed that these organizations would approach GTZ/UN and sell this idea to them. If the concept is accepted, it is suggested that private entrepreneurs would be contracted to supply prosopis charcoal to the camps. Initially, this supply would fill about 30% of the total refugee energy needs met by the GTZ project, and would progressively increase its portfolio. This efforts will be accompanied by increased capacity building for the charcoal producers using improved kilns such as the Casamance and the Indian oil drums.

The policy implication of this concept is that there should be an enabling environment for charcoal producers to trade in prosopis charcoal production and marketing. There have been discussions on legalizing prosopis charcoal, which saw the preparation of a Cabinet memo. However, this issue has not been finalized and will perhaps be fully addressed in the proposed Energy Bill.                   

7.3 Follow-up issues

During the period of the study, the CSDI managed to secure legal recognition for a group of small-scale charcoal producers in Garissa district. They were issued with a license by the district forest authorities to facilitate the production and movement of charcoal in the district. This group was also allocated space in Hodhan Farm at the Farmers Training C entre at Garissa to conduct their activities.

As a follow up to this study, CSDI intends to commission another survey which will be looking at the markets for prosopis charcoal. This survey will attempt to establish the existing market for charcoal in the three districts, focusing on the production rates and consumption levels in the three districts. Producer innovation in charcoal production is a function of the existence of reliable markets. This second study will try to determine the kind of relationship between the supply and demand sides of the business, and how CSDI can add value to sustainable charcoal production in dryland Kenya.

8.0 References

Kenya Forestry Research Institute. 2002. ‘Study on Feasibility of Charcoal Production from Commiphora Species.’ KEFRI, Nairobi, Kenya

Hussein, Noor M. 2004. ‘Monitoring Report of Firewood and Refugee Impact on the Environment around Dadaab.’ Forestry Department, Garissa, Kenya