Chapter 16.Briquetting in Sri Lanka
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Sri Lankas's main indigenous energy resources are hydro power and fuel wood. Both are limited but not yet depleted, i.e. there is still a potential for harnessing more of the about 2 000 MW hydro power potential of which about half is now in operation or under construction. The Mahaweli programme is a major scheme for the generation of hydro power and control of water supply. Clearances of forests for hydro power projects and rural development programmes have created a surge in the supply of fuel wood, which has mainly been absorbed by an expanding industrial sector.
The resulting deforestation is a severe problem, clearly showing that the use of this type of fuel is unsustainable (Sousson 1985) or would result in a complete depletion of Sri Lanka's forests within a few decades. In order to avert such a situation, numerous tree planting programmes have been started but these have not yet reached the level where they can balance the present rate of cutting.
The total usage of bioenergy is estimated to be 8.6 million tonnes per annum, or 71 % of Sri Lanka's total energy balance. About half of the biomass is fuelwood, the rest being crop wastes (mainly from coconut and rubberwood plantations). Electricity contributes to 9% of the total, while imported oil make up the balance. Most of the industrial fuelwood is consumed for drying purposes in the tea, rubber and coconut processing industries, in the brick and tile industry and in bakeries . It can not be readily substituted for by electricity. Oil will have to be imported and substitution of oil for fuelwood in this sector is likely to create such balance of payments problems that it would severely hamper the industrial production in the country.
Thus Sri Lanka gives the impression of a country with a potentially difficult energy equation, which has not yet given rise to severe energy supply problems. All the signs indicate that there will be a crisis within a timeframe of one or two decades.
Use of fuelwood within the household sector, though taking 85% of the total biomass requirement, is only to a minor degree responsible for the looming fuelwood crisis. It appears that most of the rural population gathers its own fuel from trees planted around homesteads and fields and from wastes arising in coconut and rubber wood plantations. Studies show that there is easy access to these resources, reflected by the much higher per capita fuel consumption by the rural population compared to the urban situation where a major portion of the fuel to the urban situation where a major portion of the fuel wood has to be bought for cash. This fact could be seen as a positive factor, indicating a large potential for fuelwood conservation in the household sector.
In this context it is clear that industrial energy conservation is the most essential remedy to meet an upcoming crisis. It is also in the industrial sector, where the fuel supply is on a commercial basis, that the chances of introducing fuels based on agro-residues are greatest. So far the efforts in this direction have been very modest in Sri Lanka and the ensuing results discouraging, largely because of the continuing low level of fuelwood prices.
Availability of residues
In the parts of Sri Lanka where coconut and rubberwood plantations are dominant, wastes from these crops make important contributions to the regional energy supply. It has been estimated that rubberwood and coconut wastes on an overall basis contributes to 47 % of the total biomass use in the country (Nanana-akkara 1987). The residues are burnt both in industries for drying, as in the desiccated coconut plants, and for steam raising as well as in household stoves. The coconut shells make excellent fuels, especially when carbonised. Development work in Sri Lanka is aimed at increasing the versatility of these kind of residues through gasification.
Looking at coconuts, the only waste still unexploited is the coir dust, which is the residue remaining after the husks have been converted into fibre. An estimated 60% of the husk ends up as coir dust on large wasteheaps adjacent to the fibre mills. Coir dust will have to be dried from its moisture content of about 85% either prior to briquetting or afterwards in the case of a low pressure process.
The total production of crop residues on Sri Lanka is 3.9 million tonnes (Bamard 1985). We have not found a breakdown of these figures into the various crop wastes. From one source (Samarakoon 1987) we have the following figures of residues available for briquetting:
|Coir dust||500 000|
|Paddy husk||320 000|
|Rice straw||400 000|
A residue such as rice husk will have to be densified before use outside of the rice-mills can be made possible. It is likely the patterns of India and Thailand will be repeated in Sri Lanka which would mean that there exist a surplus of rice husk but it will not be available free of charge. As rice is grown in roughly the same geographical regions as coconuts, where there are other, more convenient, fuel sources available, the prospects for a large number of rice husk briquetting projects on Sri Lanka look rather faint.
Bagasse is to some extent used within the sugar industries already today. It would be quite easy to create a surplus, if the resulting fuel briquettes could find an outlet at prices that would pay for the costs. Experience from other parts of the world suggests that this is not likely to happen, at least at current energy price levels.
Possibly the most economic residue on Sri Lanka would be sawdust, which is to a large extent unexploited and often pollutes the rivers where the sawmills are located. There is no known data about the arisings of sawdust in the Sri Lankan wood industry, nor its potentials for fuel purposes. Drawing some parallels with other countries, particularly Thailand, sawdust briquettes are normally accepted as industrial boiler and furnace fuels and in some situations even as household fuel.
In particular, charcoal made from sawdust briquettes is a high value product which in several cases is sold at prices that makes the production profitable. In Sri Lanka, charcoal is today not a very common fuel, except for some minor use in urban households and restaurants. With increased living standards it is possible that charcoal use will spread, increasing the pressure in the diminishing resources of natural wood. Production of charcoal out of residues could be one way to ameliorate the effects of such a development.
History of briquetting
It seems fair to say that the development of briquetting in Sri Lanka has been somewhat patchy. Several European manufacturers report selling machines to Sri Lanka over the past decade and it is known that some Taiwanese units were also purchased. No record of their operations currently exist however and it may be assumed that they are now defunct. As far as we know, there were no ongoing briquetting operation of any kind in mid 1987 and no solid plans existed for such operations either.
Several organisations have been doing development work in this field. The most extensive work seems to have been done by the Ceylon Tobacco Company (CTC) through its subsidiary CTC Services Ltd. They have mainly been interested in coir dust briquetting but have also studied the briquetting of rice husk, tobacco dust and saw dust.
Using a Japanese screw extruder (Shimada) they have done experimental briquetting of all the above mentioned materials with good results (Lecamvasam 1987) in that the resulting briquettes were of reasonable quality, which is in line with our general view that most screw extruders and mechanical piston machines produce briquettes with acceptable characteristics. The technical problems encountered were related to the high moisture content of coir dust and saw dust and the high silica content of the rice husk.
The development stopped when CTC same to the conclusion that large scale operation would not be economically feasible, mainly because of logistical problems of gathering the raw material and the low cost of competing fuels.
The last activity in the briquetting field by CTC was the operation of the Kadirana pilot plant for low density briquettes using the process developed by Mr Samarakoon. This project is discussed in more detail below.
A case study
During our visit to Sri Lanka in mid-1987 we met together with representatives from the Ministry of Energy, CTC Services and Mr Samarakoon to discuss the process developed by Samarakoon and tested in the Kadirana coconut fibre mill by CTC. Operation of this pilot plant had discontinued a short while before our visit. The reasons given for this decision were organisational rather than technical. As the process according for the people involved worked well and profitable, it is worth describing here.
Coir dust from the daily production of a mill, or from its waste heap, is mixed with a binder in the proportion of 1:100 by weight. The binder used in the trials was lime. A rotary mixer ensures a good blending of the two material before the mix is introduced in the press. In the pilot plant, the press was an old tobacco baling press in which the material was spread in layers between trays of corrugated metal measuring 16 × 16" (400 × 400mm). The press was filled with 13 such layers and when hydraulic force was employed, water was pressed out of the material through holes in the side of the matrix, thus decreasing the initial moisture content of about 85% down to 60%. The resulting briquette, 16 × 16" and about 3 cm thick, was reported to drop to about 25% in 10-15 days. The production rate with this setup was about 1 ton of product per day. It had three press matrixes in rotation and the total drying surface was about 10 000 m².
The resulting briquettes weighs about 2 kg if the moisture content is 20 %. It has a density of about 400 kg/m³ and seems to be withstand normal handling and storage without deterioration. Though it is not brittle, it can be broken by hand into logs along surface indentations thus providing for the stoking of small boilers and stoves.
Though the individual briquette is far less dense than those resulting from high pressure processes, the form of the briquette makes it suitable for stacking, which results in reasonable storage volumes.
During the operation of the pilot plant, which went along for two years ending in September, 1987, briquettes were delivered on a commercial basis to 7 customers (5 desiccated coconut industries, 1 oil mill and 1 tile manufacturer). They were reported to be satisfied with the briquettes except for the tile manufacturer who could not produce tiles of the desired quality.
The average price received from these customers were 800 its/tonne (US$29 ). This is a premium over the normal fuel wood price to industry which lies in the 300-500 its/tonne range (US$11-18 ). Higher fuel wood prices exist. For example, a special hardwood called weera is trucked in to the desiccated coconut industries which burns this wood in its drying furnaces. The cost was reported to be 1 200 its/tonne (US$43).
Table 9: Costs of Full Scale Low-Pressure Briquetting Plant
|Investment 125,000 Rs: Annuity 17%||21 250|
|Raw materials: Coir dust||NIL|
|Lime: 1% and 700 its/tonne||2 800|
|Electricity: 8 kWh/tonne at 1.80 Rs/kWh||5 750|
|Insurance, taxes etc||25 000|
|Total costs||129 800|
|Annual production||400 tonnes 325 its/tonne|
The production cost for the coir-dust briquettes in the Kadiran plant was reported to be 450 its/tonne, i.e. it left a margin for transportation costs and profits of about 350 its/tonne. No exact breakdown of this production cost can be given but we have made the estimate shown in Table 9 based on information given by the operators:
Although the coir dust in this calculation is assumed to be free of charge, this is not the real case. In the Kadirana plant, this cost was paid in the form of a charge for land rental with an annual amount of 50 000 Rs. This brings the real production cost up to the 450 its/tonne (US$16 ) reported by the operators.
The process is patented by Mr Samarakoon and at the time of our visit it was unclear whether there were going to be any commercial applications in Sri Lanka. Undoubtedly the process offers a low-cost alternative to the more traditional briquetting methods covered in this report.
As a matter of fact, given the low fuelwood prices in Sri Lanka, it is unlikely that any such high-pressure process could produce briquettes at prices competitive with the current fuelwood supplies. As pointed out earlier, sawdust charcoal briquettes would be the likely starting point for the development of residue briquetting in the country, perhaps parallelled with some low-pressure coir-dust briquetting.
Chapter 17.Briquetting in Thailand
The energy scene in Thailand can be divided in two parts: the rural part which encompasses most of the country and 70% of the total population of 50 million and the urban and industrialized part which is mainly concentrated in Bangkok and its immediate surroundings.
Gas and oil from offshore finds can support a share of the energy demands in the urban area and from industry but imported oil still accounts for the major share of the country's energy balance (UNDP/World Bank 1985). Electric power based on these fuels and from lignite will also become dominant in this area. Charcoal will remain the major cooking fuel for the urban poor however, as well as in restaurants and small food industry for the foreseeable future.
For the rural population, wood and charcoal are the main fuels and, at least in parts of the country, deforestation has made them in short supply. The underlying reason for the deforestation is not the cutting of wood for fuel but clearing of land for plantations and the use of wood for the sawmill industry. In the part of Thailand where the scarcity is most acute, which are parts of the Central Plains and much of the north-east, gathering of fuelwood is a cumbersome task and a cause for severe hardship among the population.
Table 10: Energy Consumption in Thailand, 1983 ('000 toe)
|Fuelwood||2 971.7||15.0||2 986.7|
|Charcoal||2 219.7||280.2||2 499.9|
|Bagasse||1 205.0||-||1 205.0|
|Subtotal||6 923.3||295.2||7 218.5|
|Petroleum products||2 259.4||6 938.2||9 197.6|
|Electricity -||190.5||1 236.8||1 427.3|
|Subtotal||2 488.1||8 316.6||10 804.7|
|Total||9 411.4||8 611.8||18 023.2|
Source: World Bank 85
However, despite the problem of deforestation, in the monetized fuelwood sectors, market prices of fuelwood are still quite low. They are at a level (0.3 - 0.5 Baht/kg or 12 - 20 US$/tonne) where it is very difficult for manufactured fuels to compete, whatever the cost of the raw material and the process.
Land-owners are encouraged to plant fast growing tree species such as eucalyptus on land previously cleared for farming purposes. Though the planting of eucalyptus is not without controversy in Thailand, it is increasing. Such fuelwood plantations may help to solve the country's shortage of indigenous paper and charcoal and, possibly, become a fuel source for the electrification of the rural parts.
One special problem has been created through the inflow of refugees from neighbouring countries. In the refugee camps along the Kampuchean border, cutting of wood is prohibited. Thus they constitute the main market for the suppliers of saw-dust and rice-husk briquettes still active in Thailand.
Availability of resources
Thailand has a good base for the production of a variety of crops. Rice is dominant but with high production figures also for cassava, sugar cane, maize, sorghum and soybeans. Coconuts are grown on the Malacca peninsula and groundnuts can also be viewed as a potential raw material supplier for fuel production. The wood industry, though [united in size, constitutes a largely untapped source of material for briquetting.
Table 11: Arisings and Energy Content of Major Residues
|Residue||Arisings ('000 tonnes)||Yield (t/ha)||Energy content ( × 1015J)|
|Cassava stalks||7 115.20||5.76||39.84|
|Maize stalks||6 004.60||3.58||33.62|
|Rice straw||25 318.50||2.63||212.66|
|Rice husks||4 219.75||0.44||58.23|
|Sawdust and shavings||0.77|
Source: Bhattacharya 1985
Rice-husk yields at the rice-mills vary within the range 20-30 % of paddy rice depending on milling efficiency and rice quality. The total production of rice-husk in Thailand for the crop season 82/83 was estimated to be 4.2 million tonnes. Output of rice mills vary widely; one survey (Bhattacharya 1985) included rice mills ranging from 24 tonnes/day to 500 tonnes/day. Seven out of eight rice-mills in this survey used rice- husks for the generation of steam through direct firing.
However, there is still a surplus of rice-husks even after steam generation, which in favourable cases can be sold to brick manufacturers for combustion and poultry farms for bedding at prices in the range of 3.7 to 9.3 US$/tonne. This does not dispose of total arisings and the disposal of rice-husks (and rice-husk ash) creates a problem. It seems common that, in rural areas, villagers can bring home rice-husks free.
Thailand produced in 1982 about 2.3 million tonnes of sawn timber, yielding sawdust at an average rate of 10% of the input. Though sawdust is wet, which means that is has to go through an expensive drying process before it can be briquetted and the total waste production is low compared to rice-husk, it is a popular material for briquetting as customers prefer the product, especially when carbonized after briquetting. Uncarbonized sawdust briquettes can still only be marketed in the refugee camps, where they are favoured before rice-husk briquettes. The charcoal briquettes, or tube charcoal as the fuel is termed, is sold at a premium price over wood charcoal, due to its higher density and heat value, and its even quality.
Sawdust can to some extent be sold to customers such as papermills and (allegedly) fish farms at prices ranging from 5 to 20 US$/tonne. Similarly to rice-husks, internal use and sales to other customers of sawdust account for only a minor portion of the total production. A surplus which has no alternative use other than for fuel making is thus at hand.
Rice-husks and sawdust are the only materials known to be used as raw materials for fuel briquettes of any quantity. A number of low-pressure extruders have been sold for the production of "green-fuel briquettes using leaves, bagasse and other wet materials but the quantities produced are probably insignificant.
History of briquetting
A factory in the Pathum Thani province imported a set of four briquetting machines and a rotary dryer from Taiwan around 1978 in order to produce sawdust briquettes. This event appears to mark the beginning of briquetting in Thailand (Bhattacharya 1985).
The number of factories increased sharply in the beginning of the 80's, following the influx of refugees from Kampuchea. The refugee camps provided a captive market for the briquettes which stimulated a number of entrepreneurs to start up production. Although the first briquetters utilized were Taiwanese of the heated die extruder type, a number of Thai manufacturers soon established themselves on the market. US. Machine was the most successful of these local manufacturers.
It is reported that V.S. Machine has delivered 200 units over the past nine years. This is an impressive market share of the about 300 machines which have been distributed in Thailand according to one estimate (Bhattacharya 1985).
The other Thai manufacturers are: T.I.S.T.R (a government research organization) which have made and distributed about a dozen machines, and S.P. Energy, which so far have only manufactured the 6 machines used in the company's own briquette production. All these manufacturers are making copies of the Taiwanese design first introduced in the country. The initial intensive sales of briquetting machines, typically to rice-mill and saw-mill owners who saw a way to get rid of some of their waste products and make a profit at the same time, quickly slowed down. Many bought several machines each, up to a dozen in one example, but most were soon left idle or in some cases, never commissioned. Often the plant owners had made the purchase at a trade fair without proper investigations of markets and production cost. To illustrate this one can look at the 200 machines originally installed by US. Machines of which only 20 are reported to be still in operation (Reines 1987).
Of all the machines installed in rice-mills (the total number of mills which have had briquetters is unknown but believed to be several dozens) only two producers remains on the open market. We visited one of these producers, S.P. Energy which still manages to produce rice-husk briquettes at prices competitive enough to be able to sell to the refugee camps. (The briquettes sell for about 4 Baht/kg at this artificial market and the price ex works in Bangkok, 600 km away is about 1.25 Baht. This should be compared to the common wood fuel price of 0.5 Baht/kg.)
Producers of saw-dust briquettes have fared better than rice-mill owners and there are still seven plants making briquettes both for the refugee camps and the open market (Bhattacharya 1988). Uncarbonized briquettes cannot be sold on the open market any more and therefore they go solely to the refugee camps. (A few temples are reported to buy some uncarbonized briquettes although the volumes appears to be insignificant).
The method of carbonizing sawdust briquettes seems unique to Thailand and was developed there by briquette producers shortly after the introduction of briquetting equipment in the country. The history and experience of biocoal in Thailand has been thoroughly investigated by Bhattacharya et al. at the Asian Institute of Technology in Bangkok (Bhattacharya 1988).
Biocoal was introduced as it was clear that uncarbonized briquettes had to compete with fuelwood at price levels which were impossible to achieve by the briquette producers. It fumed out that the carbonized briquettes were excellent substitutes for wood charcoal and could be produced at competitive prices. This development took place around 1982. In 1986 and 1987, new producers appeared on the fuel scene, but these were mainly aiming for the export markets. They produce biocoal from sawdust and export most of their output to South Korea and Hong Kong. Material unworthy of export is sold on local markets and is especially popular among street food vendors.
One of the largest independent producers of carbonized saw-dust briquettes has 12 V.S. machines and employs 22 people. It has a production target of 50 tonnes per month. The cost of sawdust is reported to be between 0.03 to 0.04 Baht per kg delivered (1.2 - 1.6 US$/t). To this should be added an assumed briquetting cost of about 1 Baht/kg (estimates range between 0.8 to 1.5 Baht/kg). For each kg of product charcoal, 3 kg of briquettes are used in the carbonization kilns. This results in a rough product cost of 3.2 Baht/kg (130 US$/t).
The selling price for this type of charcoal is between 4.6 and 5.5 Baht/kg depending on the quality. This probably gives a large enough margin for transport costs, dealer commissions and a reasonable profit for the manufacturer .The interesting thing about the above example though is that the plant is not set up primarily to produce charcoal briquettes to the local markets but to export boxed charcoal briquettes to Japan, Korea and countries in the Middle East. The likely use of the charcoal briquettes in these countries is for barbecuing though no price data is available.
A 1 kg three-colour box with sawdust charcoal was reported to cost 18 Baht/kg in central grocery stores in Bangkok. This example gives an idea of where the briquetting market is heading in Thailand, a country where briquetting has been widely tried and tested. It is no longer a means for solving a critical fuel problem for the rural poor but a business proposition amongst others for earning export incomes. Future developments for briquetting in Thailand seems at the moment to be rather doubtful. Sales of new machines are dropping to a tenth of its peak value and new business venturers can buy almost unused machinery on the second-hand market. The government is not particularly interested in the issue and there is currently no national programme for the increased use of agricultural wastes through briquetting
The official view is that some residues can contribute to the national energy balance, particularly rice-husks, but the economy of briquetting projects is doubtful and has to be looked at on a case by case basis (Rutanaprakam 1987).
As briquettes cannot compete with fuelwood which is available at prices ranging between 0.3 and 0.5 Baht/kg (whereas briquette production costs are at least on the 1 Baht/kg level) the question is whether depletion of the natural fuelwood resources will mean a fast increase in these comparatively low prices. Local experts doubt this for two reasons. One is that land cleared for agricultural crops has not been profitable and there is a trend to replant these areas with fast-growing tree species, a development encouraged by the government. Secondly, tree-planting on a village level can yield sufficient amounts of fuelwood within a short time, something believed to take place if and when farmers feel a real shortage of wood (Chomcham 1987).
Wood energy plantations are likely to produce some substitutes for industrial use of coal, gas and oil but then most likely in the form of chips. Briquetting this wood would mean an unecessary increase of the price which undoubtedly will have to be much higher than the 0.5 Baht/kg level for fuel wood in order for the plantations to become profitable.
What remains is the potential market for carbonized briquettes in urban areas, particularly Bangkok. It is clear that the "tube charcoal", as carbonized saw-dust briquettes are called, can successfully compete with ordinary charcoal on this market but that the potential is limited by the availability of sawdust within reasonable transportation distances.
The export opportunities for this type of fuel looks promising but this may be a side-track of the question of a global fuel-wood shortage in developing countries. The last market for uncarbonized briquettes, made from saw-dust and in one case, of rice-husks, is the refugee camps. As the situation in Kampuchea becomes normalized, this market will gradually disappear and the first fuel to be phased out is going to be the rice-husk briquettes, a fact well understood by the producer SP-Energy
Thailand stands out as a country where briquetting of agricultural wastes has been tried on a large scale, found to be too expensive, and has died out except for providing fuel for a few specialized market segments.
A Case Study
During a visit in Thailand in mid-1987, we visited S.P. Energy the last remaining rice-husk briquette manufacturer. The following is a general description of the background of the company and how it is run. The plant is owned by Mr Sayan, who functions as its general manager, together with his brother and sister. Mr Sayan has a degree in diesel technology from a university in USA and his brother has an engineering examination from a Bangkok university
In 1980 they were introduced to briquetting on a small business promotion scheme and decided to start a briquetting operation using the waste from their uncle's rice-mill.
After a very brief study of a Taiwanese screw briquetting machine they built a duplicate using, amongst other things, used auto parts for the drive and gear mechanism. During the years they have made modifications to their machines when extending the plant and replacing worn out machines but in principle they still operate with the same type of machine. In all they have now made 6 or 7 machines, all for their own use. In spite of the unorthodox origins, the machines appear to work well and produce briquettes of good quality
The rice-mill is now leased out for operation but the lease includes the free use of rice-husks which they carry in baskets from the rice-mill to their own storage pile. The pile is shielded from direct rain by plastic covers but moisture in the rice husks is one of the problems in the operation. Normally they can produce briquettes from rice-husk with up to 15% but under certain conditions they can accept up to 20% moisture.
The end of the rainy season provides for the most difficult operating conditions, both in respect to the moisture content of the raw material as well as its availability. They have bought rice-husks from other rice-mills at such times and for this reason they also keep a truck for transportation.
S.P Energy operates continuously with 2 machine operators per shift plus 1 welder There is a foreman during the dayshift plus one extra hand for unspecified duties. At the times when they operate all 6 machines during the night shift, a foreman is needed for overseeing the operation and helping out with any problems which arise.
The welder's job is to rebuild the wom screws of the presses which wear out rapidly. He does this continuously throughout the day.
The workforce get their food and lodging at the factory provided for by the plant owner as part of their salary They are employed all around the year and get one free transportation to their home villages in the north each year.
The company sells the entire production to middlemen who, in a chain containing several links, supply the briquettes to the refugee camps along the Kampuchean border 600700 km from Bangkok. Mr Sayan claims not to have a long term contract and complained that this fact prevented him from planning his production and storage needs ahead. He sold his product ex works for 125 Baht/kg and he was aware of the much higher price his briquettes fetched at the final point of consumption. This price is, according to one source, said to be 4 Baht/kg.
Transportation cost accounts for only a part of the difference between the price paid to S.P Energy and what the briquettes fetch in the refugee camps. The cost of a truck for taking the briquettes to its market is about 3 000 Baht. Even if the load is only some 6 tonnes, this would mean a transport cost of about 0.5 Baht per kg
Mr Sayan sees no future in his briquetting operation. He has seen his competitors dose down one by one leaving him the only supplier of rice husk briquettes with only one outlet, an outlet he thinks will remain only for another couple of years. His plans for the future involves going into fish farming which he regards as much more promising than briquetting.
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