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Chapter
12.Introduction to country reviews
Chapter
13.Briquetting in Africa
Chapter
14.Briquetting in Brazil
Chapter
15.Briquetting in India
Chapter
16.Briquetting in Sri Lanka
Chapter
17.Briquetting in Thailand
Chapter 12.Introduction to country reviews
The briquetting of agro-residues is of relatively origin in developing countries. The technique was adapted for organic wastes about 50 years ago in industrial countries, having been first developed to briquette low-grade coal, but interest waned in the 60s. It has only been revived in the 80s on any significant scale in most developing countries. This has meant that there is a lack of any systematic information about how briquetting plants have performed in practical operation. The success or failure of briquetting is very dependent upon the agricultural and fuel context in which it is applied so there is only a limited amount of help which can be obtained from technical appraisal or from the experience of plants in industrialized countries.
There is a great shortage of information upon the practical performance of such plants. They are small-scale, often remote, and operated by people who have relatively little opportunity to communicate their experience to the wider world. The central objective of this study was to search out operating plants and to prepare case studies about their experience.
It is not a practical proposition to visit every country in the world in search of briquetting plants. After a considerable amount of letter-writing and discussion with other workers, it was decided to focus on four countries and one region; India, Thailand, Sri Lanka, Brazil and East Africa.
Each of these countries has had some history of operating briquetting plants with varying degrees of success ranging from modest prosperity to, for the moment, complete failure. The countries to a large extent chose themselves because of this. The experience of briquetting in Africa has, so far, been largely confined to a set of isolated projects which have had rather little interaction with each other. In order to provide a rather more systematic framework it was therefore decided to look at a regional experience in Africa rather than that of a specific country. The two countries in the general region with the widest experience of briquetting are Kenya and the Sudan so some emphasis will be given to these two countries.
In each case, we have tried to use a similar form of presenting information so that it is possible to make comparisons. However each country is very different so the emphasis within each case-study is different.
Chapter 13.Briquetting in Africa
Introduction
Africa is too large a region to be described adequately by any single generalisation about its energy context or the availability of agricultural residues. Nevertheless in reviewing the status of briquetting plants in different parts of the world there is a striking resemblance between the apparent situation in African countries which is quite distinct to that seen in countries in Asia and South America. It is possible to devote a chapter to Briquetting in Africa" whereas "briquetting in Asia" would not be a useful heading.
This conclusion is based upon a considerable amount of secondary material about briquetting plants in Africa as well as visits made to a number of countries in east and southern Africa. This illustrates one of the paradoxes of the situation; that much of the attention of reports about briquetting has been derived from plants in Africa which have been, by and large, unsuccessful either technically or commercially (and sometimes both) whereas very little has been written about countries where the technique has had at least limited success. By itself, this situation reflects one of the problems with briquetting plants in Africa; they are conceived of as "projects undertaken by development agencies rather than businesses and, as projects, they are extensively reviewed.
The African case-studies are centred on Kenya and the Sudan, countries where there are operational plants of various kinds. Two of these in Kenya were visited and the prospects for another discussed with the project consultants. In the Sudan, extensive discussions were held with those responsible for plant operations and two pilot plants were visited.
In addition, information was collected about biomass densification operations in Zimbabwe, Tanzania and Ethiopia in the course of visits to these countries.
Information about francophone countries in west and central Africa was obtained by discussions with agencies and consultants who had worked on briquetting in these countries. Additional data about briquetting in Ethiopia was obtained from a previous SIDA study (SwedFarm 1986) and a large feasibility study undertaken by the joint UNDP/World Bank ESMAP programme. (World Bank 1987) We were helped by other consultants with data about Tanzanian units. Other information came from the authors of a report recently published by the British Overseas Development Administration. (ODNRI 1987)
Energy background
There a big differences in the energy situations of the range of countries mentioned above. However, there a few common aspects which are important for the development of briquetting.
First, all the countries considered are heavily biased towards wood consumption, particularly in the household sector. Demand for wood and wood products, particularly charcoal which is the fuel of choice in many urban areas, is often growing and deforestation is an actual or potential problem.
The supply of a substitute for fuelwood in the household sector has emerged as a policy priority in many countries and in the funding agencies which support many energy projects. This policy has assumed a priority status even where current fuelwood prices are quite low. This has led to a somewhat paradoxical situation in a number of countries as projects are being initially supported despite the fact that they are clearly not economic at present prices but are then, sometimes, being judged on the basis of these prices.
Second, except in southern Africa, oil and, possibly, natural gas are the main fossil fuels available and form the basis of most fuel supplies to medium to large industries. Coal is only used to a significant extent in Zimbabwe of all the countries discussed here. In Zimbabwe, and the other southern African states where coal is abundant, its main use is in industry. There is very little household use of coal although efforts to encourage this are being made.
The result of these two factors is that almost all briquetting projects in Africa have been concerned with the supply of a substitute household fuel. Exceptions are two of the Kenyan plants discussed here and defunct plants in Zimbabwe and Zambia.
Availability of residues
There is very little data available about crop residues in Africa. The survey by Barnard and Kristoferson provides some data about existing use of residues for fuel which is mainly negative in the sense that usually only marginal uses had been found. No general data on unused residue arisings is given. This suggests a conclusion confirmed by subsequent visits; that agricultural residues have, until recently, not aroused much interest as fuels in most African countries. There is however some evidence from countries where deforestation is a major problem that the use of residues is increasing. An example is Lesotho. However no systematic data on this trend appears to be available.
Estimates made for specific countries suggest that often quite large residue volumes may be surplus to existing needs. In Ethiopia, a World Bank survey (World Bank 1987) suggested that "at least 3 300 000 tonnes of surplus coffee, cotton, wheat and maize residues are produced annually though not all are economically accessible." Even the much reduced figure of those residues which arise from centralised state-farms, put at about 600 000 tonnes, is large enough to make a significant contribution to the Ethiopian energy economy.
In the Sudan, it has been estimated that 2.4 t/ha of surplus cotton stalks are available after the consumption by local households has been subtracted. More than 370 000 ha are planted with cotton; the volume of residues theoretically available could supply about 5% of total Sudanese fuelwood needs.
In both these cases, the residues considered did not arise from a basic food staple grown for auto-consumption but from crops usually grown in medium or large agricultural units as a cash crop often for export. All the briquetting projects that have been identified in Africa are based upon a similar residue base. The residues derive from localised origins, such as groundnut or coffee mills or extensive cotton growth, rather from a widespread crop (such as rice in India or Thailand or, less obviously, coir in Sri Lanka) or wood residues (as in Brazil).
The main staple crops in Africa, with the possible exception of maize, do not produce a large and centralised volume of residues suitable for briquetting such as rice-husk in Asia. Only one case has been located, in Ethiopia, where it is proposed to briquette maize residues and the feasibility of this has not been established. The cost estimates produced are high because of the need to collect and transport field residues even in the favourable circumstance of a centralised state-farm.
Nevertheless, the volumes of residues indicated by the above figures for two countries not chosen for their obvious agricultural endowment suggest that significant volumes of surplus residues do exist in most African countries though they may need to be identified and their point of arising established.
History of briquetting
The history of residue briquetting in Africa is largely one of single projects in various countries which have usually not been successful. There is no case identified of a set of briquetting plants based upon similar technology and expanding into a market sector. Nor is there much evidence of any learning process though in the recent period, for example in Ethiopia and the Sudan, there is some sign of a more careful and monitored approach.
The first interest in briquetting seems to have started in the late 70s when a number of European companies tried to sell machines in various countries. (A few briquetting machines may have been installed in the early 50s but these have vanished without apparent trace.) There appear to have been some individual successes but there is no clear evidence of any of these machines still operating. Some of the first machines were sold to briquette groundnut shells in west Africa; two Hausmann presses were installed in 1979 at the shelling plant at Dosso, about 140km south-east of Niamey in Niger, and in 1981, a machine was commissioned at the Kaur plant in the Gambia following various market studies and technical tests carried out in Denmark.
Neither of these plants has been successful; the reason in the Gambia appears to be uncompetitiveness in the market whilst the Dosso plant suffered not only from marketing problems but from a shortfall of shells from the processing plant. A description of the complexities of the Gambian situation has been recently published. Although dogged by persistent problems including non-availability of spareparts, it has established that briquettes are marketable to households. (Khartoum Workshop 1988)
In Malawi, a number of screw briquetters were purchased from Taiwan by the Wood Industries Corporation in 1981 and installed at sawmills in Blantyre, Zomba and Dedza. The plants produce briquettes from sawdust at a price which cannot compete with wood. The plants at Zomba and Dedza are reported to be inoperative whilst the Blantyre plant operates only sporadically.
In Zimbabwe, a pelletising machine, based on a cattle-feed unit, was installed at a groundnut shelling plant outside Harare in 1984. It operated successfully in technical terms though the roller die was expensive to maintain and replace but the product was difficult to sell except as a low-cost industrial fuel substituting for coal. The plant is currently used to supply pellets to the animal feed and fertiliser industries in which role it may be successful (Bennett, 1988).
In Zambia, another pelletising plant was set up to process sunflower husks as a feed for a coal-fired boiler. It is reported (ODORI 1987) that the resultant material was too variable for proper steam control and that extensive boiler modifications would be required to utilise the material. It is possible now that the husks will be used raw in another boiler; in any case the machinery in not used.
A plant based upon a small Spänex machine was opened in Rwanda in 1982 by a cooperative set up to provide employment for the handicapped. There were initial technical problems in operating the plant but the main difficulty was that the small scale of production made it very difficult to establish continuity in the market as only about 50 households were being supplied at any one time. Production stopped in 1984 although it may have recommenced recently. Another plant in Rwanda is based upon papyrus. Its activities have recently been described. (Martin, 1988) Although dogged by problems, including lack of spare parts, it established that papyrus briquettes are marketable to households.
In Ethiopia, one of the few private plants known to exist in Africa was started in mid-1985 in Addis Ababa. A low-pressure piston machine supplied by Eco-Briquette was bought by private individuals after they had obtained information about similar plants in India. The raw-material is saw-dust (60%) plus some coffee parchment and cotton-seed husk. The briquettes are sold mainly to middle-class hotels in Addis which have installed woodburning stoves of some sophistication.
The machinery is reported to function reliably but has the draw-back of requiring a binder material which must be imported from abroad. There are difficulties in obtaining a foreign exchange allocation for this and the binder cost a significant part of the operating costs of the plant. Nevertheless, in 1988, the owners were hoping to expand their production to about 3 thousand tonnes annually if they could obtain sufficient raw material.
A major programme of briquetting is planned for Ethiopia based upon various agro-residues from state-farms. These have not yet begun operations.
There is an operational plant in Tanzania at Moshi based upon a screw-briquetter supplied by the Orion Coal Company. This plant uses sawdust and has a capacity of about 1 800 tonnes annually. The original plan was to carbonise the product and sell as a competitive fuel to charcoal. However, all the product is purchased by local institutions who burn the briquettes direct.
There is no apparent problem in selling but at a price which only covers operating costs; no capital recovery element is included - which is perhaps as well as the plant is reported to have cost at least US$200 000.
Another plant based upon coffee-husks, which again intends to carbonise the briquettes, is built but not yet commissioned by the Coffee Marketing Board at Moshi.
In the Sudan a number of units have been installed in the past two years which are now working. A piston unit has been operating on groundnut shells in a location some distance south-west of Khartoum and it will be joined by another unit when a new building has been completed. Another, semi-mobile unit was designed to work on cotton-stalks in the Gezira project but failed to overcome operational problems. It is now installed at a groundnut factory near Khartoum where it appears to be operating successfully.
In addition to these high-pressure units, there has also been some successful application of low-pressure compaction to large quantities of bagasse which exist at Kashma El Girba and New Halfa in the Eastern Zone.
These use low-pressure TERSTARAM presses made in Belgium which give a compaction pressure of about 6-8 MPa, about 20 times less than the high-pressure briquetters. The briquettes, which are more appropriately called blocks, are made by mixing bagasse with waste molasses and then compressing. The blocks are air-dried for three days before bagging. The bagasse is taken from large stockpiles which exist close to the plant.
There is a ready market for the blocks from brick-works and from the domestic sector and there are plans to build a further three plants each with an annual output of about 1 500 tonnes. The region where they are made is one of great wood shortage and, because of an influx of refugees, there is great pressure for alternative fuels
Finally, there is a proposal put forward after some careful market research and product testing for the utilisation of cotton-stalks by carbonization followed by roller-briquetting. It is not known yet whether this approach will be developed.
In Kenya, two plants have been installed, the earliest in 1983, which utilise coffee husks for the production of briquettes and pellets for industrial boilers whilst there is also a unit which produces charcoal from coffee-husks and then makes this into briquettes using molasses as a binder. The industrial plants used a piston and a screw briquetter and a large pelletising plant whilst the char-briquette plant used a screw extrusion press.
There is a plant in Ghana operating successfully on wood residues based upon two Taiwanese screw-presses. The plant is fully commercial and sells its output to bakeries. At Diourbel in Senegal, there is reported to be a plant which produces pellets made from groundnut shells which are said to be sold for fuel. The main use of the pelletising plant is however to manufacture cattle feed.
Case studies
Plant origins
Nearly all the plants mentioned above were financed by development agencies with the exception of the private operations in Ethiopia and Ghana, the units in Zambia and Malawi and the two, industrial units in Kenya.
The Kenyan plants were set up on the initiative of companies which are both members of the same industrial group though operated separately. The original impetus to set up the plants came in the early 80s following the large oil-price increases when there was a concerted effort to reduce dependence upon imported oil by moving to local fuels and to reduce overall fuel consumption. The primary motive was financial both because of immediate gains and because oil supplies were perceived as likely to become irregular as well as more expensive.
The first move was into the use of firewood followed by attempts to find a firewood substitute. It is possible that the second phase was partly motivated by considerations of national policy; firewood was and is relatively cheap but deforestation was seen as a national problem which it was not good to exacerbate.
The installation of a plant, based upon a large pelletising machine, at another company in the group was based upon a desire to move out of oil into a local fuel. The decision to do this was probably strategic rather than based upon prospects of quick financial returns as the machine involved is very expensive.
The third Kenyan operation comes from a quite different direction, that of searching for ways to provide a substitute in household use for charcoal which is the dominant urban and pert-urban fuel. Its origins were in various studies made of fuelwood supply and use and the perception that there was likely to be a fuelwood crisis if demand was not reduced. The project is externally funded and should be seen as a pilot-plant to investigate the potential for the future rather than a commercial operation.
The Kenyan plants are somewhat atypical of other African briquetting operations in that their origins are internal to the country even though, in the third case, external funding is involved. In other countries, briquetting plants seem to have suffered from a lack of internal dynamic which has meant that when problems have arisen the plant has been either abandoned or remained idle for long periods.
The Sudanese plants are much more typical of other African projects in that each one was funded as a separate project by various development agencies. Both the Energy Research Council and the National Energy Administration have had on-going programmes examining briquetting. The overall impetus to each project has been the growing problem of wood shortages in the Sudan and the increasing price of fuelwood and charcoal.
Equipment used
There are two generalisations possible about the equipment used in African plants; the first is that almost no generalisation is possible for virtually every kind of unit has been tried once though usually only once.
This does in fact cover a serious problem for, in many cases, equipment has been used which is barely appropriate for the task and which has been adopted for reasons outside the needs of the situation. There are three broad reasons for this.
First, there is no doubt that in some cases, the requirements of national funding agencies to buy plant from their own domestic manufacturers has led to the use of machines which are not the best suited to the conditions. It would be invidious to quote examples and it should be emphasised that in a number of cases the equipment provided by tied-aid has proved quite adequate. But even in situations where the plant is effectively free to the user, it is clearly wrong, to use an actual example, to provide equipment whose operational power costs per unit of product are greater than the price of coal or fuelwood in local markets. It is also wrong to supply plant whose maintenance needs cannot be supplied locally and which require frequent visits by overseas engineers if the plant is to be kept going.
Second, there is a clear "guinea-pig" character to many of the plants in Africa; that is they have been installed as pilot-plants to test new techniques or types of product. There is nothing wrong in principle with this; new ideas, particularly ones which are a break with existing practices in Europe or the U.S.A., have to tried out in practical operation. However, such plants have to be installed as test-beds and given appropriate support and monitoring, neither of which have always been forthcoming It is also important that expectations should not be raised too high otherwise failure may produce demoralization.
In a sense, these two issues are mirrors of each other; in the first, existing, rather sophisticated plant is unloaded on to users who cannot utilise it and in the second, untried "appropriate" technology is presented as a proven technique.
The third problem is simply lack of good information by plant buyers about the range of alternative products. This is a common problem not confined to briquetting machinery but it has led to the installation of plant which could probably be improved on. It is difficult, for example, to believe that it was the best choice to buy a machine for use in Ethiopia which depended upon an imported binder particularly when the raw-material, sawdust, can easily be briquetted by binderless techniques.
The second generalisation is that this diversity of machines have one common feature - they are often extraordinarily expensive.
For example, the Tanzanian plant based upon sawdust is estimated to have cost about US$200 000 in foreign exchange for equipment to produce up to 1 600 tonnes of briquettes annually. A Taiwanese screw-press which, operated under a similar regime to the Tanzanian plant, could probably produce about 600 tonnes annually was imported into Kenya in 1986 for under US$6 000.
Similarly, in the studies undertaken by the World Bank for a project to install briquetting plants in Ethiopia, the cost of a 750 kg/hr piston briquetter is put at US$86 000 whilst a similar capacity screw machine is put at US$63 000. In Brazil, the 1987 price of a machine with 1 100 kg/hr capacity, is US$39 000 whilst the piston briquetter, of about 500 kg/hr capacity, imported privately into Ethiopia cost US$33 000 in 1983.
In some cases there is no doubt a hefty premium being paid for plant installation costs, for spares and for a variety of extra equipment costs. However, it is very difficult to construct any good economic reason for briquetting plants when faced with such huge initial capital costs.
The performance record of the plants has been patchy with numerous reports of breakdowns and high maintenance costs. The main cause of these appears to be inadequate time spent in setting up the machine and problems with variability of the feed. This latter may derive from the fact that African plants, as noted, often work on a rather singular raw-material mixture which may not have been met previously by the manufacturer. There is therefore a need to adjust some of plant parameters rather systematically at the startup of the plant to achieve optimum conditions. If this stage is omitted, as it often is when foreign engineers are employed to install the machine, then the plant can suffer persistent problems.
The two Kenyan plants visited did not suffer badly from commissioning and maintenance problems as both were installed inside factories with a considerable degree of onsite technical support. In the Sudan, the semi-mobile unit suffered many operational problems, in part because it was badly sized in certain of its components and partly because the conditions under which it was required to operate were too extreme.
These are both common problems. The sizing of plants for unusual residues (in this case cotton-stalks) requires greater care than manufacturers or consultants often give it. The initial feed mechanisms, in particular for piston machines, need to be matched to the piston for each type of residue. Some manufacturers with experience mainly in wood wastes do not do this properly. European manufacturers are also sometimes too optimistic about their plants performing well in adverse conditions. Moving a plant from field to field in northern Europe is simply not comparable with an equivalent operation in the Sudan
The various projects which hope to market char briquettes were all at a pilot plant stage using equipment specially made up for the project. The Sudanese plant, in particular, is hoping to move to a commercial stage but at least one or two years of field trials will be required first.
Residues used
The two residues most frequently encountered were coffee husks and ground nut shells. In Kenya, all the plants used coffee residues. The use of sawdust and cotton stalks has also been reported and there have been experiments with the use of papyrus reed in both Rwanda and western Kenya.
As noted above, neither of these crops are staples though groundnuts are widely grown throughout Africa. Although their residues may often be sufficient to feed two or three plants it is difficult to see briquetting being other than a marginal activity based upon coffee and groundnuts alone. It is therefore interesting to note that the proposed Ethiopian plants will use residues from wheat and maize straw; the latter in particular could provide a large and widely spread resource base is successful. In Ethiopia, it has been estimated that 3.0 tonnes/ha of straw and 0.6 tonnes/ha of cob are available and, at present, unused.
Groundnuts provide a good feed for briquetting either in piston machines or pelletising plant. The brief operation of the Harare groundnut pelletising plant was stopped because of the economics of production not because of poor-quality pellets. In general, it seems as if groundnut plants are always located at the shelling plant and that the residue is free. Its only alternative use is direct combustion in an industrial boiler.
The two piston machines now operating in the Sudan both use groundnut shells and report good results.
The experience in briquetting coffee-husk is mixed. Two types of residue are obtained from coffee; the husk, which is obtained from the cherry after it is picked and which can be either wet or dry depending upon the way the coffee is processed, and coffee parchment which is obtained from the green bean at the final processing mill. The latter is a relatively small part of the crop, about 4%, but arises in a dry form at a central location convenient for processing. The husk is a much larger part of the total crop, about 23% of the initial crop before drying. This residue is usually available in a less centralised form and may be wet if a washing process is used rather than sundrying.
In Kenya, both types of residue were available, dry, in Nairobi and the preferred feed was husk, that is the complete outer berry, for the piston briquetting machine whilst the pelletising plant was designed to run on coffee parchment. The briquettes obtained from a mixture of coffee husk and saw-dust were rather soft and had a high ash content whilst it was found difficult to make satisfactory briquettes or pellets at all from 100% parchment. Coffee husk could be used on its own to make satisfactory briquettes.
The feed mainly used was a husk/sawdust mixture in one plant and a husk/parchment mixture in the other.
This conclusion about the relative utility of husk and parchment does not appear to be borne out by the results of the test briquetting programme for the proposed Ethiopian plants in which coffee husk gave the least satisfactory briquette of all the residues examined on virtually all the combustion and handling tests used whilst coffee parchment gave reasonable results. It is difficult to know whether these variations arose because of the use of different briquetting processes or because of variation in the residues. In any event, the briquetting of coffee residues clearly needs to be preceded by a specific testing programme.
The coffee residues used in Kenya were all purchased from the Coffee Growers Association for up to 270/- per tonne (about 16 US$/tonne) in mid-87 though this price seems to vary both seasonally and between purchasers. The higher price is a sharp increase from the 105/- used in the original financial assessments by one of the plants. The rise seems to have been imposed by the Growers Association once they saw a market develop rather than because of any competitive use. There is some use of coffee husk as a soil mulch but this accounts for only a small part of the residues produced. The Association has a local monopoly of coffee residue.
There were no problems with moisture content of coffee residues; in fact at the pelletising plant, steam-conditioning was used as the original material was too dry. A similar technique was employed at the groundnut pelletising plant in Harare; the use of too-dry material there had given rise to the jamming of the die - a serious problem in a pelletising die with its numerous small holes.
The other component of the feed at one Kenyan plant was sawdust and this was purchased from a nearby saw-mill for about 60/- per tonne (about 3 US$/tonne) whilst wood-shavings cost 125/- per tonne. The sawdust was often wet and had to be dried.
Markets
The main generalisation that can be made about briquetting in Africa is that it has often proved difficult to sell briquettes against the competitive price of wood or charcoal.
In Niger, the wholesale price of briquettes in 1985 was 18 FCFA/kg and the retail price was 22 FCFA/kg; the retail price of wood was 10 FCFA/kg. In the Gambia in 1981/82, the estimated retail price of briquettes was 1.88 bututs/1 000 kcal whilst the price of charcoal was 1.53 bututs/1 000 kcal.
In Kenya, in 1987, the price of firewood bought in bulk was quoted as 325/- per tonne whilst the cost of briquettes produced on a piston-machine was calculated to be 413/- per tonne. In Tanzania, briquettes were being sold at Tsh 3/kg as against a charcoal price of Tsh 5/kg but this briquette-price covered only plant operating costs and was based upon a free sawdust feed.
The pilot-plant in Kenya producing carbonised coffee-briquettes was unable to compete in the Kenyan charcoal market though it was reported that a similar plant being set up in Uganda was able to sell its product as the local charcoal supply situation was very stretched. A similar situation appears to exist in the Sudan where fuel-supply to refugee camps is very strained.
In Ethiopia, a careful study of the economics of briquettes (World Ban* 1987) concluded that under the most favourable circumstances with a plant located in Addis Ababa and a dry, centralized residue, the full production cost of briquettes from coffee parchment would be nearly 38 US$/tonne ax-factory, assuming that the residues were free, whilst the retail price of firewood in Addis had moved up to 83 US$/tonne. Under these circumstances, briquettes could compete with firewood but, in less favoured locations using more difficult residues, the delivered cost to Addis Ababa rose to 98 US$/tonne for coffee-pulp, 114 US$/tonne for cotton stalks, 115 US$/tonne for wheat straw and 140 US$/tonne for maize residue.
It should be noted that the only plant actually operational in Ethiopia is reported to produce at operating costs of 140 birr/T in 1986 or about 68 US$/tonne using a mixed feed input which cost about 45 US$/tonne. This excluded maintenance and marketing costs and any capital charge. The owners suggested that a market price of about 170 US$/tonne was required to meet all charges; the market price actually obtained in 1986 was 126 US$/tonne but this is reported to have increased in the past year or so. The plant now seems to be operating at a profit.
The primary marketing problem for briquettes in Africa is their high price relative to wood and charcoal. It is not clear whether this poor competitiveness arises mainly from the very high capital cost of the plants or the low price of wood; probably the balance between the two varies between countries. In Kenya, the main problem is undoubtedly the fact that wood prices remain low, apparently well under 1 US$/GJ in heat terms. At such prices, virtually no alternative fuel can be justified except on long-term strategic grounds. At the other extreme, the prices quoted above for Ethiopia seem to have a very heavy capital cost component. Thus the annualised capital charge for cotton-stalk briquettes was calculated to be 34 US$/tonne out of a total ex-factory production cost of 82 US$/tonne.
The persistent problem of lack of price competitiveness has obscured the issue of customer acceptability of the product.
The target market usually aimed for in African briquetting projects has been households burning either wood or charcoal. As noted above, the choice of this market has been largely conditioned by initial policy perceptions rather than any actual consideration of the markets for which briquettes are suitable. However only very small quantities of briquettes ever appear to have been sold to households. It is noticeable that the only truly commercial operations which have been identified, those in Ethiopia and Ghana, sold their products to "middle-class" hotels burning firewood or to brick kilns.
It is also interesting that the Tanzanian project, originally set up to produce charred briquettes for the household market, is actually selling "raw" briquettes to institutions who readily take all their output. Other instances could be quoted of plants which began by targeting the domestic sector but eventually sold their product to industry.
The only systematic consumer survey of household acceptability to be undertaken appears to have been one undertaken by Bois de Feu (Association Bois de Feu, 1985), a French agency, using mainly the groundnut briquettes produced at Dosso. In this, briquettes were distributed free to 70 families with a survey worker checking on consumption weekly.
This survey revealed that most of the cooks quickly found out that the best way of using the briquettes was by mixing them half and half with firewood as they have different but complementary burning characteristics. This result from the field confirms many of the combustion tests carried out in laboratories. Under mixed fuel conditions, it was found that the special stoves which Bois de Feu distributed to families were not required.
The study showed that briquettes could be sold to the household sector and could even acquire a cachet of "modernity" but only if they were competitive in price and were supplied on a consistent basis. This is confirmed by the Rwanda plant; households took the briquettes when they were available but the inconsistent supply situation meant that no market base was ever built up.
In Ethiopia, the owner of the small private plant has described (Kekeba, 1988) how the initial marketing of his product required a lengthy programme of market testing and sales promotion. This plant is one of the few which has gone out actively to seek customers. The results have been, overall, favourable though some initial resistance had to be overcome about possible health problems when used by households.
In Kenya, the plants visited both burnt their products in their own boilers which had been converted from oil-burning.
Some combustion problems were reported from husk/sawdust briquettes because of ash problems. The briquettes were also rather soft and tended to crumble. (This seems to be a common problem with coffee-based briquettes). The pellets were said to be a good fuel.
In the Sudan, the Renewable Energy Project of the Energy Research Council has been doing various kinds of household market survey on the products of low pressure and carbonised briquettes. The results have generally been favourable though the samples have been small. In addition, it has been found that the products of the two piston machines find a ready market in both small industry and households.
A final, optimistic conclusion to what is an otherwise often depressing review of African briquetting It seems that briquettes of all types can find a market niche when they are produced regularly enough at prices not too far out of line with the competition. It may be that the easiest area to exploit is the substitution of wood in small boilers in hotels, institutions and small industry. However, there is some evidence that briquettes can be acceptable in households without the use of special stoves provided the consumer has sufficient time to work out the best use of the briquettes.
Local manufacturers
There are no existing manufacturers of plant in any African country. However, a mechanical engineering company in Zimbabwe, Airflo Ltd. is sufficiently interested in the area to have built a test machine for possible future manufacture. It is a hydraulic-piston machine and although it is in a fairly unfinished state, the test-rig has successfully briquetted sawdust and some agro-residues. It is not clear whether the company will move to market a machine; there is no briquetting at present undertaken in Zimbabwe so they would probably have to set up their own briquette production unit to spark interest. However, they were confident that they could produce a working machine for a price which undercut European manufacturers by at least 50%
It is doubtful if many other African countries could emulate this as their mechanical engineering sector is not developed sufficiently. However, a number of projects (and the consultants associated with them) seem to underestimate the potential for local maintenance and the provision of spare parts. An interesting description (Martin, 1988) of a project in Rwanda, carried through on a very limited budget, suggests that local maintenance of a piston machine is possible using the correct type of welding rod to build up the piston head. This is certainly possible for screw machines as demonstrated in the Ghanaian plant. Yet too many other plants in Africa seem to assume that the smallest technical problem requires a new spare part from Europe or Japan using foreign exchange which is often unavailable.
There is no doubt that much more attention should be paid to the issue of local maintenance in future projects. It is of particular importance that the components of the system should be simplified as far as is compatible with good operation.