Review of the Niger Coal Carbonization Project

19839 October 1994 Review of Policies in the Traditional Energy Sector Discussion Paper Series REVIEW OF THE NIGER COAL CARBONIZATION PROJECT October, 1994 Erkki Korpijaakko RPTES Consultant The World Bank, Africa Region Directorate General for International Cooperation The Netherlands  RPTES Program Staff Boris Utria, Task Manager Max Wilton, Senior Adviser Azedine Ouerghi, Energy Economist Suzanne Roddis, Projects Assistant For additional information on the RPTES program or the Discussion Paper series, please contact: RPTES Program Western Africa Department The World Bank 1818 H Street, NW Washington, DC 20433 tel: (202) 473-4488 / 473-0719 fax: (202) 473-5143  REVIEW OF POLICIES IN THE TRADITIONAL ENERGY SECTOR RPTES REVIEW OF THE NIGER COAL CARBONIZATION PROJECT October, 1994 Erkki Korpijaakko RPTES Consultant NOTE: THIS DOCUMENT WAS PRODUCED AS PART OF A CONSULTING ASSIGNMENT BY THE AUTHOR TO THE RPTES PROGRAM. IT IS NOT AN OFFICIAL WORLD BANK DOCUMENT. THE FINDINGS, INTERPRETATIONS AND CONCLUSIONS PRESENTED HEREIN ARE ENTIRELY THE RESPONSIBILITY OF THE AUTHOR.   KORPIJAAKKO: NIGER COAL, PROJECT REVIEW, 1994 . . WORLD BANK EXECUTIVE SUMMARY 1.0 PROJECT INTRODUCTION AND OBJECTIVES The present report is a review of a coal carbonization project funded by the Canadian International Development agency and carried out by Cartier Engineering (La Societe d'Ingenierie Cartier Ltee, Groupe Monenco, Canada) in Niger to produce carbonized coal as a substitute fuel for firewood in Niger homes and institutions. This review is a part of a large-scale regional review of the traditional energy sector in Sub-Saharan Africa commissioned by the Energy Unit within the Africa Technical Department of the World Bank. The regional review is done in phases and the present report is part of Phase IIa which covers a group of Sahelian countries, of which Niger is one.  FORPIJAAKKO: NICER COAL PROJECT REVIEW, 1994 .... WORLD BANK The objectives of the present work is to briefly review the status of the abovementioned Niger coal carbonization project entitled "Production d'un combustible domestique, projet d'usine pilot". Summarized, the specific objectives of the review are: 1. A brief background history and rationale of the carbonization project. 2. Technical status of the carbonization plant. 3. Economic state of the project emphasizing certain aspects of the cost of carbonization, feedstock, transportation and future resource availability and markets. The overall objective is to help verify the technical and economic viability of the enterprise. 2.0 PROJECT RATIONALE AND BACKGROUND HISTORY Large areas of the world suffer from the lack of suitable household energy source. In their search for everyday cooking fuels, people have denuded large areas of forests. The result has been local environmental deterioration in general and, on a larger scale, an increased greenhouse effect as the forests, the most effective C02 sinks, have disappeared and the C02 level in the atmosphere has risen and the advance of desert in regions, such as the Sahelian zone of Africa. -2-  KORPiJAAKKO: NIGER _DAL PROJEC' REVIEW 994 . . ORLD BANY To help reduce the overuse of wood, a number of projects have been financed to search for suitable substitute fuels for firewood. The aim of the coal carbonization project was, and is, to promote the use of clean coal, i. e. semicarbonized coal, as a substitute fuel in Niger and, if feasible, in other regions were there are coal reserves. Cartier (Monenco), thanks to its expertise in energy use of peat, got first involved in Africa, in Senegal, in a study of using mangrove peats as a source of energy. After this, already in 1984 Cartier Engineering started to investigate the use of peat in Burundi. In 1989 a brick kiln to carbonize peat and other biomass, such as wood shavings, coffee husks and rice hulls, was built in Burundi. It produces carbonized biomass briquettes for the domestic market as a substitute for wood charcoal and firewood. In 1986, Cartier Engineering studied the overall use of coal in Niger. The project led into another project, whereby a sample of Anou-Araren coal was carbonized in Burundi and tested in a number of families in Niamey. The encouraging results led to the present project, which consists of a pilot plant to produce carbonized lumpy coal and briquettes for the domestic market in Niger. -3-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW. 'W4 . ORLD BANK The following is a concise summary of the main findings of the project, which is reviewed in more detail in the main body of the present report. 3.0 PLANT'S PRODUCTION CAPACITY Raw coal, because it emits acrid smoke, is not usable untreated as domestic fuel in small kitchen stoves. To render the coal usable, it is partially carbonized in a kiln by anaerobic process, pyrolysis, whereby it is exposed to high temperatures to drive its volatiles out only leaving enough of them to allow it to be burned, but at a low enough level to render it smokeless. The carbonization kiln built at Tchirozerine to carbonize Anou- Araren coal was planned to be capable of producing at least 3000 tonnes of carbonized coal per year. The tests confirmed the planned capacity of 3000 tonnes and by operating the kiln in three 8 hour shifts, a capacity of 4500 tonnes a year. For testing, the kiln operating time was limited to 20 day periods interrupted by coal preparation periods of 30 days. This mode of operation was imposed by the shortcomings of the ancillary equipment, notably by a low capacity of the vibrating screen to screen the feedstock. As a result, the total annual capacity at the present pilot plant equipment configuration is about 730 tonnes. Technically, the kiln -4-  FOURP'AAKKO NI(ER ^OAL, PROJECT REVIEW :994 .... WORLD BANK is capable of producing up to 4500 tonnes annually when operated 300 days a year and at three 8 hour shifts daily. Due to a large percentage of fines in the feedstock and in the carbonized product, 35 and 40% respectively, up to 60% of the final product could be briquettes. Briquetting tests have established that the carbonized and uncarbonized fines can be briquetted at a rate of at least one tonne per hour. If the briquette press were operated also 300 days a year at three 8 hour daily shifts it could produce about 7200 tonnes of briquettes, or the kiln would have to produce 12,000 tonnes of carbonized coal a year. Thus one press is capable of handling the production capacity of 2 or 3 kilns. Technically, the planned 3000 tonne annual production capacity can be achieved simply by acquiring the needed additional pieces of equipment. The plant at its present state is, after all, a pilot plant and never was planned to be an industrial facility without additional investment in equipment. The total investment to attain the planned 3000 tonne annual production level is $US 115,000. To reach a stepped-up level of, for instance 10,000 tonnes annually, the investment needs for imported equipment are about $US -5-  KORPL2AAKKC: YIGER COAL. PROJECT REVIEW I9Q4 .... WORLD BANK 238,000 and for the local materials about $US 211,000 bringing the grand total to about $US 449,000. This is an order of magnitude estimate and does not include taxes, duties, freight costs and the influence the recent devaluation of FCFA has on the costs of imported materials. 4.0 FEEDSTOCK, AVAILABILITY, QUALITY AND COST Anou-Araren mine has over 13 million tonnes of reserves. The original plan was to supply Sonichar power station for 30 years at an annual production capacity of 300,000 tonnes. However, for last few year the power station has run at a partial capacity consuming only about 110,000 to 120,000 tonnes of coal annually. The coal in the Anou-Araren deposit is in two seams of varying thicknesses. Of these two seams, seam A is located closer to the surface under an overburden of about 50 metres. Seam B is below seam A separated from it by an intercalation which varies in thickness and on average is only about 0.2 m thick. Both seams A and B are on average 2.50 m thick according to the information supplied by Sonichar. Seam A is of a lower quality coal with a relatively high ash content up to 63% while seam B has an ash content about 30 to 40%. To optimize the usage of these two seams, -6-  KORPLjAAKKO: NIGER '-DAL PROJEC- REVIEW 1994 .- WORLD BANY the power station was designed to run at about 49% ash content. To achieve the required parameters, the coal from these two seams is mixed in a suitable ratio. At the present mining rate, there is coal for the power station for more than 60 years. As also, according to some preliminary indications, the coal in seam A appears to improve in quality as the mine advances towards west, it is probable that even seam A coal might be usable for carbonization in the future. Based on the estimated ration of A to B seam coal (1 to 1), it appears that at today's power station consumption rate there would be about a 90,000 tonne annual reserve of seam B coal for the carbonization plant for the next 30 years. To realize this would require an increase of the mining rate to the full capacity of the mine or to 300,000 tonnes annually. As a result, there would be a 90,000 tonne annual surplus of seam A coal, if it were not suitable for carbonization. These calculations are only of magnitude of order and would require a thorough study of detailed deposit data and the required mixing ratios. In any case, they give an indication of the potential of the existing site. The coal deposit of Anou-Araren appears to extent to the north indicating further reserves. According to other exploration projects, about 40 km north of Anou-Araren, there are large deposits of good quality coal, albeit at a depth of 400 metres, or -7-  (ORP'JAAKKO: NIGER COAL. PROJECT REVIEW 19q4 .... WrORLD 3ANK at this time not economically minable. These deposits have been estimated to contain up to 2250 megatonnes of good quality coal. An exploration project between Tahoua and Filingue in southern Niger has also revealed an existence of a number of coal seams at varying depths (25 to 50 m) and with a seam thicknesses from a few decimetres to several meters (up to 7 m). The quality of coal according to the preliminary analyses is in many cases better then that of Anou-Araren (lower ash content, higher carbon content). This area awaits further exploration work, but if economical, would open up possibilities closer to the large markets in the south. Anou-Araren coal has a high ash content, 30 to 60%, depending on the seam. For power station use it is low quality, for carbonizing to produce domestic fuel it is quite acceptable. The high ash content, and low calorific value render it a suitable feedstock for carbonized coal to be used in domestic stoves. These characteristics ensure a slow burning rate and low enough temperature to allow good cooking conditions. Presently Sonichar delivers feedstock to the carbonization plant at a total cost of 3720 FCFA/tonne composed of 2310 FCFA/tonne of mining cost and 410 FCFA/tonne for transportation cost. The unusable fines can be returned to the power station for a credit of 2310 FCFA/tonne after the return transport cost has been paid. -8-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW i 94 . . . WORLD BANK This cost is limited and will go up at a higher demand level, because it would create extra mining costs at the mine. The cost above about a 10,000 tonne annual demand might go up to 10,000 FCFA/tonne. The cost figures are not yet firm and will have to be discussed with Sonichar. 5.0. CARBONIZATION COST AND SALES PRICES Calculated on the basis of pilot plant experience, the production costs are about 27.5 FCFA/kg. This cost is subject to changes in the cost and quality of coal as well as other coats items, such as the labour rates, as is normal. Presently, perhaps the most important factors which may change the production cost profoundly are the cost and quality of coal. The future coal mining needs depend largely on the health of the uranium mines. If they were shut down, there would be very little need for electricity in the total region. If for some reason also the power station would have to be closed down, the only coal user would be the carbonization plant. It is obvious, that in this case the coal cost would have to be adjusted to the quantity and quality needed for the plant. The quality also affects the production costs. The quantity of fines determine the percentage of briquettes of the final product. Briquetting test indicate that the production cost of briquettes is about 34.5 FCFA/kg. Obviously the sales price in this case would -9-  KORP'JAAKKO; NIGER -OAL, PROJECT REVIEB 1994 .... WORLD BANK have to be higher than for the lumpy coal to recover the difference in the production cost. Carbonized coal has been sold at the plant gate at about 29 FCFA/kg. The retailers sold it (1993) in Tchirozerine and Agadez for 40 and 35.5 FCFA/kg in "small quantities" (2.5 kg containers) and in "large sacks" (45 kg) respectively. The respective prices in Arlit were 50 and 44.5 FCFA/kg. Demonstrations and price discussions in Niamey indicated that there would be no resistance to prices over 50 FCFA/kg, even 75 FCFA/kg was suggested. This gives an indications about the price ranges. At 62.5 FCFA/ kg coal would be at the efficiency level of firewood if it were sold at 25 FCFA/kg as was done on average (1993). Carefully controlled tests have shown that one kilogram of carbonized coal does the same cooking task as 2.7 kg of firewood. The cost ratio will have changed considerably in 1994 as the price of wood has in many cases almost doubled. According to a more recent information (1994) coal and briquettes are presently sold in Niamey at 67 FCFA/kg (3000 FCFA/sack of 45 FCFA kg). Market potential evaluations in Niger (unnamed source, 1994) have estimated coal prices from 34 FCFA/kg in Agadez (near the plant) -10-  KORP!JAAKXO: NIGER COAL PROJECT REVIEW 1994 .... WORLO BANK to 55.5 FCFA/kg in Zinder (525 km from the plant), 67 FCFA/kg in Tillaberi. The same evaluation estimates a total potential annual consumption of 6900 tonnes by institutional users alone, initially. 6.0 PRODUCT PROMOTION AND ACCEPTANCE Carbonized coal was promoted through well coordinated programs carried out by Cellule Technique de Coordination, Foyers Ameliores et Energie (Ministry of Mines and Energy) first in Niamey and later for the carbonization project in Agadez. The product was well received by the housewives, once they had been trained in its use and had learned its convenience and safety. By 1993 according to sales records a total of 2450 stoves had been sold to families and the military camp in Tchirozerine and the hospital in Agadez were converted to carbonized coal. The latter realized 60% savings in the energy costs over firewood. The total number of Onersol stoves may be close to 3000 when also the unrecorded sales by the blacksmiths are added to those recorded by Socaren. In addition to this figures, about 400 to 500 ABBAZE stoves should be added to realize that the families who use or are ready to use coal may be close to 3500, if also the stoves sold directly by blacksmiths were taken into account. -11-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW 1994 .... WORLD BANK Further promotion has been carried out in Niamey and Tahoua and on radio and television, as well in the schools and fairs and in front of representatives of the private sector and the Government. This new fuel requires a special stove. One was designed by ONERSOL (Office national de 1tenergie solaire) and tested and found to be efficient. Its basic price was originally (1992) about 1300 FCFA. The price was accepted by the user, although it is higher than 750 FCFA commonly paid for a simple improved firewood stove. Presently (1994) the stoves are sold in Agadez area for 1200 to 1500 FCFA each. By the beginning of 1993 some of these stoves had been in a daily use for more than one year without showing any signs of unusual wear. The abovementioned Niger market evaluation (unnamed source) has investigated the institutional market by using an ABBAZE (ABZ) stove type Gaya. A total of 30 of these stoves would be sold at a cost of 53,000 FCFA each plus the cost of special pot for the stove at 25,000 FCFA each in 16 centres across the country. According to the same study, the institutions taking part in the program would realize about 55% savings in their energy cost by using coal at the abovementioned price ranges. -12-  {CRPIJAAKKO: \:GER COAL, ?ROJECT PEVIEW 19Q4 --- WORLD BANK 7.0 TRANSPORTATION COSTS Niger is a large country with a sparse population and long transportation distances resulting in high transportation costs. The carbonization plant is located at the only existing mine in the country, creating a product transportation problem. Official quotation (1992) gives a transportation cost of 14.4 FCFA/kg from the plant to Niamey (1040 km) on backhaul basis. Experience during the course of the project with independent truckers has shown that the cost can be lowered as low as to 8 FCFA/kg. However, only a few trips were done and for any long-term operations the truckers would have to include allowance for depreciation and maintenance and come up with rates to reflect these higher expenses. Some coal has been, and is being, transported to Niamey by independent truckers. At the time of writing no cost information was available. The willingness of the consumers to pay the present (1994) rates of 67 FCFA/kg for the product in Niamey makes transportation even at the official rates feasible even to Niamey. The official (1992) backhaul rate to Tahoua (480 km) is 5.7 FCFA/kg, to Birni n'Konni (520 km) 6 FCFA and to Dosso (880 km) 9 FCFA/kg. -13-  KORPIjAAKKO: NIGEF COAL, PROJ ECT REVIEW 9 994 . ... WORLD BANK 8.0 ENVIRONMENTAL IMPACT The carbonization plant emits gases. Their concentrations were measured in the plant chimney and on the field 100 metres downwind from the plant with Gastec tubes. Compounds measured are carbon dioxide and monoxide, hydrogen sulphide, sulphur dioxide, nitrogen oxides (NO), phenol, acetic acid, ammonium and hydrogen. All the concentrations were below the accepted levels or even at the level not detectable. The standard acceptable levels used were those set by American Conference of Government Industrial Hygienists. The same measurements were done at the user sites in normal kitchen conditions. No concentrations above accepted levels were detected, indicating that this fuel is safe. According to the users, it does not bother their eyes, nor does it smell like the smoke from wood fires. The overall environmental effect has not been studied in a detailed manner. It appears, that the benefits of using carbonized coal in place of firewood are positive. Its use certainly reduces deforestation and consequently the advance of the desert in Niger. Indirectly its use should thus reduce the CO2 emissions and the greenhouse effect. Other benefits rising from the conservation of trees are various edaphic, climatological and habitat benefits -14-  KCRPIJAAKKO: NIGER COAL. PROJECT REVIEW, 1994 .... WORLD BANK which also benefit quality of human life. The safety and the convenience of use also reduce the workload of housewives and thus improve their life. If a zero emissions facility is needed, it is possible to construct one. In some high production coking plants the emitted side products are incinerated and used to produce electricity for the plant. 9.0 FUTURE At the present time, the Niger carbonization plant, although it is technically capable of producing its full capacity of 3000 to 4500 tonnes of carbonized coal per year, is limited to an annual 730 tonne rate. The reason is in the under-capacity of ancillary equipment. The plant awaits further investment to bring the auxiliary equipment capacity to the kiln's full capacity level from the pilot plant stage. According to information supplied by the on- site personnel, the plant has been idle since late 1992, except for the briquetting operation which is slowly turning out briquettes fabricated from the large stockpile of carbonized fines produced during the project. The briquettes are sold locally and also in markets as far as Niamey. -15-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW 1994 .... WORLD BANK The markets are well established and the user is willing to pay a premium price for the carbonized coal over the price of firewood. The environmental impact of the plant and the product is below the applied standard for acceptable level and the overall environmental impact apparently positive in comparison with the use of firewood. To establish accurately the investment and pricing and other economic parameters, an on site fact verification is needed. As well, equipment and freight pricing in North America is needed. With all the upgraded information on hand, a final analysis of this promising technology can be carried out. -16-  XORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS REVIEW OF THE NIGER COAL CARBONIZATION PROJECT Table of Contents LETTER OF TRANSMITTAL EXECUTIVE SUMMARY Page Table of Contents. . . . . . . . . . . . . . . . . . . . . .(i) List of Tables . . . . . . . . . . . . . . . . . . . . . . (iii) 1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . .1 2.0 SCOPE AND OBJECTIVES . . . . . . . . . . . . . . . . . 2 3.0 PROJECT BACKGROUND HISTORY . . . . . . . . . . . . . . 3 3.1 Introduction . . . . . . . . . . . . . . . . . 3 3.2 Study of Peat as a Substitute Fuel . . . . . . 4 3.3 Initial Coal Utilization Carbonization in Niger 6 3.4 Niger Coal Carbonization Pilot Plant and Marketing Project . . . . . . . . . . . . . . . 9 4.0 TECHNICAL REVIEW . . . . . . . . . . . . . . . . . . . 10 4.1 Introduction . . . . . . . . . . . . . . . . . 10 4.2 Feedstock Considerations . . . . . . . . . . 11 4.2.1 In Situ Quality and Quantity . . . . . 11 4.2.2 Quality of Coal Delivered to the Plant . 13 4.3 Kiln and Ancillary Equipment Performance . . . 15 4.3.1 Introduction . . . . . . . . . . . . . . 15 4.3.2 Ancillary Equipment . . . . . I . . . . 17 4.3.2.1 Conveyors . . . . . . . . . . . 17 4.3.2.2 Screen and Crusher . . . . . . 19 4.3.2.3 Kiln Controls . . . . . . . . . 21 4.3.3 Kiln Performance . . . . . . . . . . . . 22 4.3.3.1 Production Capacity . . . . . . 22 4.3.3.2 Kiln Performance Considerations 25 4.3.4 Product Review . . . . . . . . . . . . . 29 4.3.4.1 Chemical Characteristics . . 29 4.3.4.2 Physical Properties . . . . . . 30 4.3.4.3 Utilization Properties . . . . 32 4.4 Stove Technology . . . . . . . . . . . . . . . 34 4.4.1 Traditional Stoves . . . . . . . . . . . 34 4.4.2 New Designs . . . . . . . . . . . . . . 35 4.4.2.1 Cherchar Stove . . . . . . . . 35 (i)   KORpIJLAAKO: NIGER COAL. PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 4.4.2.2 Project Stoves . . . . . . . . 36 4.4.2.3 ABBAZE Stoves . . . . . . . . . 38 4.4.2.4 Institutional Stoves .39 4.5 Production of Briquettes . . . . . . . . . . . 41 4.5.1 Introduction . . . . . . . . . . . . . . 41 4.5.2 Equipment and Preparation of Materials . 41 4.5.3 Properties of Briquettes . . . . . . . . 43 4.5.4 Quantities; Briquettes vs. Lumpy coal . 45 5.0 SUMMARY OF TECHNICAL REVIEW . . . . . . . . . . . . . 46 5.1 Introduction . . . . . . . . . . . . . . . . . 46 5.2 Present State of the Project . . . . . . . . . 47 5.2.1 Kiln Production Capacity . . . . . . . . 48 5.2.2 Briquetting Capacity . . . . . . . . . . 48 5.2.3 Quality of Feedstock and Product . . . . 49 5.2.3.1 Feedstock Availability and Quality . . . . . . . . . . . . 49 5.2.3.2 Product Quality . . . . . . . . 50 5.2.4 Stove Technology . . . . . . . . . . . . 51 5.3 Upgrading Prerequisites . . . . . . . . . . . . 53 5.4 Future Technology . . . . . . . . . . . . . . . 54 6.0 REVIEW OF COST AND MARKETING ASPECTS . . . . . . . . . 54 6.1 Introduction . . . . . . . 54 6.2 Pilot Plant and Production Cost Aspects . . . . 55 6.2.1 Equipment Investment Cost to Attain a 3000 Tonne Annual Production Level . 55 6.2.2 Investment Costs for a Stepped-up Production Capacity . . . . . . . . . . 57 6.2.3 Coal Quantity and Quality vs. Its Price 60 6.2.4 Various Carbonization Cost Aspect . . . 66 6.2.4.1 Indirect Effect of Fines on the Carbonization Costs . . . . . . 66 6.2.4.2 Consumption of Electricity . . 67 6.2.4.3 Effect of Pollution Control on Costs . . . . . . . . . . . . . 68 6.3 Transportation Cost Review . . . . . . . . . . 69 6.4 Marketing Review . . . . . . . . . . . . . . . 76 6.4.1 Product Promotion . . . . . . . . . . . 76 6.4.2 Product Pricing . . . . . . . . . . . . 78 6.4.3 Stove pricing . . . . . . . . . . . . . 81 6.4.4 Private Sector Participation . . . . . . 83 7.0 NIGER COAL RESOURCE POTENTIAL . . . . . . . . . . . . 84 7.1 Introduction . . . . . . . . . . . . . . . . . 84 7.2 Coal resource Potential in the North . . . . . 85 7.3 Coal Resource Potential in the South . . . . . 86 8.0 MISCELLANEOUS CONSIDERATION . . . . . . . . . . . . . 92 8.1 Training and Motivation . . . . . . . . . . . . 92 8.2 Security and Political Conditions . . . . . . . 93 (ii)  KORPIJAAKKO: NIGER COAL. PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 9.0 ENVIRONMENTAL IMPACT REVIEW . . . . . . . . . . . . . 95 10.0 FUTURE OF CARBONIZATION IN NIGER . . . . . . . . . . . 99 List of Figures Figure 1 Southern Niger Coal Exploration Zone . . . . . 87 List of Tables Table I Basic Chemical Properties of Product and Feedstock . . . . . . . . . . . . . . . . . . . 29 Table 2 Bulk Density of Different Fractions of Feedstock (Raw Coal) and Product . . . . . . . 31 Table 3 Basic Chemical Properties of Briquettes Compared with Carbonized Coal . . . . . . . . . 43 Table 4 Minimum Equipment to be Imported to Run the Carbonization Plant Continuously . . . . . . . 56 Table 5 Additional Equipment and the Cost to Attain a 10,000 Tonne Annual Production Capacity from the 3000 Tonne Level (Imported equipment) . . . 59 Table 6 Additional Equipment and the Cost to Attain a 10,000 Tonne Annual Production Capacity from the 3000 Tonne Level (Local equipment and other costs) . . . . . . . . . . . . . . . . . . . . 59 Table 7 Transportation Distances . . . . . . . . . . . 72 Table 8 SNTN Transportation Cost Quotation . . . . . . 72 ( iii )  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 1.0 INTRODUCTION The present review is part of a wider regional review of the traditional energy sector in Sub-Saharan Africa carried out by the World Bank. The overall review is supervised by the Division for the Private Sector Development and Economics within the Africa Technical Department (AFTPS) and commissioned by the Energy Unit, also within the Africa Technical Department. The overall objectives of the regional review are: (i) undertaking a retrospective evaluation of the objectives, scope and approach of the traditional energy sector work done to date and its resulting policies, strategies and programs on the evidence of stated public policy, its execution by agents in the public and private sector, and activities of external assistance agencies and organizations; (ii) identifying the principal critical inter-sectorial linkages that influence the operation of the traditional energy sector in selected countries, and developing a conceptual framework and strategy for the sector within this enlarged operational context; (iii) preparing a set of recommendations of new policy directions for the development of the traditional energy sector, and for the establishment of implementation priorities by national institutions and economic agents, complemented by appropriate instruments of external assistance; (iv) identifying projects and/or programs and thus to arrive in the shortest possible time at operational results; and (v) disseminating the operational results among the donor community at large. -1--   KORPIJAAKKO: NIGER COAL, PROJECT RNVIEW/1994 .... WORLD BAPK/AFTPS Due to the wide scope of the overall review, the World Bank has divided it into a number phases. One phase (Phase IIa) covers a group of five Sahelian countries, Senegal, Gambia, Mali, Niger and Burkina Faso, which have been perceived to have severe energy problems and in which extensive work has been already carried out and which have experience in alternative policy approaches and whose environments are similar to each other and whose neighbouring areas possess complementary data bases. The present work is part of the review and covers the technical and economic feasibility of producing partially carbonized coal in Niger as one of several possible substitutes for household fuels, with an emphasis supplying the Niamey household market. The project was carried out by Cartier Engineering (La Societe d'Ingenierie Cartier Ltee, Groupe Monenco, Canada) and funded by the Canadian International Development Agency. It is hoped that the present report will allay the perceived doubts as to the viability of the carbonized coal and coal briquets as substitute fuels in Niger. 2.0 SCOPE AND OBJECTIVES The objectives of the present work are to shed more light into the background and the present state of the production of partially carbonized coal and briquettes as a substitute fuel for the Niger households. -2-  KORPiJAAKKO: NIGER COAL. PROJECT REVIEW/1994 WORLD BANK/AFTPS The objectives of the report in detail are as follows: (i! A summary review of the background, implementation and current status of the coal carbonization briquetting plant at Tchirozerine (Anou-Araren). (ii) A review of a number of questions on the cost of carbonization (iii) A review of questions on the cost of raw coal and its availability for carbonization depending on factors such as the quantities needed and the status of other conditions affecting the mining operations at Anou-Araren coal mine (e.g. the state of the uranium mines in Arlit) (iv) The effect of the transportation costs on the viability of the process (carbonization). (v) A brief review of the results of the Tahoua-Filingue region coal exploration project and its possible effect on the process. 3.0 PROJECT BACKGROUND HISTORY 3.1 Introduction Cartier Engineering (La Societe d'Ingenierie Cartier Ltee) got involved in Africa in the early 1980's in projects aimed at alleviating the problems caused by the lack of sources of domestic fuel, i.e. cooking and heating fuels. This lack is felt very acutely in various parts of Africa including countries such as Burundi in eastern Africa and Niger in the Sahelian zone of western Africa. The following is a brief history of the development that led to the establishment of a coal carbonization pilot plant to -3-  KORPIJAAXXO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS produce partially carbonized (devolatilized) coal as a substitute fuel to firewood in Niger. 3.2 Study of Peat as a Substitute Fuel The first step in the investigation to search for a substitute fuel for firewood and wood charcoal was carried out by Monenco Consultants through Cartier Engineering in Senegal in 1983. Monenco got involved in this study as it had a wide expertise in the use of peat for a number of purposes, one of them as a source of energy. At that time, La Compagnie des Tourbieres du Senegal was promoting the use of peat a as possible power station and domestic fuel in the country. The expertise of Cartier Engineering (Monenco) was engaged to survey and discuss the possibility of using mangrove peats of Senegal as a source of energy. At this time Burundi surfaced as a country that already was mining small quantities of peat for horticultural uses and also had carried out studies on energy uses of peat through Finnish and Irish companies financed by various international agencies such as USAID and FINNIDA. In Burundi, peat had been promoted as a domestic fuel in its raw form. However, it contains large quantities of volatiles (up to 60%) and upon firing emits large quantities of acrid smoke. This characteristic rendered it unacceptable to the Burundian housewives as a domestic fuel, since most cooking is done -4-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 . WORLD BANKIAFTPS in small stoves without chimneys allowing the smoke to linger around the cooking area. In fact, peat acquired a reputation as an unsuitable fuel in Bujumbura. This reputation was further strengthened by the wood charcoal lobby which saw peat as a threatening competitor. Cartier entered the energy picture in Burundi already in 1984. In 1987 further contacts were made with the representatives of ONATOUR (Office National de la Tourbe), the producer of peat in Burundi, to investigate the possibility of producing partially carbonized peat in the form of briquettes as a substitute fuel to wood charcoal. It was felt, that by eliminating the problem of smoke, peat would be an acceptable fuel for the Burundian households. As a result of the interest, a project to produce carbonized peat fuel was* financed partly by CIDA (Canadian International Development Agency) and partly by IDRC (International Development Research Centre, Ottawa). For the purpose of this project a pilot plant kiln, made of clay bricks, was built in Bujumbura and the required briquetting equipment imported from Canada. This plant is still producing carbonized briquettes made not only of peat but also of mixes of other biomass, including wood shavings and coffee and rice husks. -5-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS In Burundi, there still is resistance (psychological) to the use of peat, even carbonized, because of its initial bad reputation as a smoky fuel and from the wood lobby. But as long as peat is not mentioned as an ingredient, it appears that the carbonized biomass fuel is accepted. 3.3 Initial Coal Utilization and Carbonization in Niger Cartier carried out a study on the use of coal in Niger in 1987. The project was entitled " Etude sur les impacts de developpement industriel a partir de d'exploitation du charbon". During the course of this project, it became apparent that coal could be considered as a substitute fuel for firewood which was getting scarcer in Niger, where the advance of the desert is felt very strongly. However, the characteristics of untreated coal do not lend it usable in the small stoves used in the Niger households. Also, at this time it was evident, that additional exploration to search for better quality coal, than the one found in the existing Anou-Araren mine, was necessary. There were indications, that the same deposit could contain better quality coal towards Solomi-Sekiret about 40 km north Anou-Araren. To verify this possibility, a limited exploration project was undertaken in the Solomi-Sekiret area in 1988. Three holes were dug manually without any success. In addition to them, three holes were -6-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 WORLD BANK/AFTPS drilled and sampled. The coal sampled and analyzed from these sites gave approximately the same quality results as for the Anou-Araren coal. While the exploration work was underway, it was decided to test the possibility of carbonizing coal from Anou-Araren. For this purpose a channel sample covering the entire coal seam with the two existing seams (seams A and B) was extracted from Anou-Araren and sent to Canada for testing. The test, since it was done on a very limited quantity of coal, indicated only that it was possible to carbonize this coal and probably to produce a product usable in domestic stoves. To follow up the possibility of producing carbonized coal as a domestic fuel, a larger scale carbonization test on the Anou-Araren coal in the brick kiln in Bujumbura, Burundi was undertaken. For this purpose, about 15 tonnes of coal from seam B, which is of a better quality than that of seam A, were manually passed through a 100 mm sieve, packed in 200 litre oil drums and sent by a Niger Air Force Hercules aircraft to Burundi. The coal was successfully carbonized in Burundi. Part of the product was in the form of lumps. The fines were briquetted by using molasses as a binder. About three tonnes of the produce were shipped back via commercial airlines to Niamey for testing. -7-  KORPIJAAKXO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS The testing was carried out by CTFED (Cellule Technique de Coordination, Foyers Ameliores et Energie Domestique; Ministere des Mines et de l'Energie) under the technical supervision of Cartier Engineering. Testing was done in a traditional area of Niamey (Yantala bas inhabited by what can be specified as "traditional" families, and in a military section inhabited by the families of the "garde republicaine", considered to be more modern in their lifestyles than the traditional families. In each area 10 families were selected for testing. The testing agency CTFED, mentioned above, started the project with scepticism believing that it would be very difficult to win housewives over to use a totally new fuel. This scepticism was based on their earlier experience with the resistance they had met when introducing improved stoves. However, to their surprise the families tested accepted the new fuel almost totally without any reservations. This result prompted the Niger government to seek further testing of carbonization of the Anou-Araren coal locally in a new setup; interest which led into the project under review.  XORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 3.4 Niger Coal Carbonization Pilot Plant and Marketing Project Prompted by the encouraging results of the first limited consumer tests on the use of carbonized coal as a domestic fuel in Niamey, the Niger government initiated the procedure that eventually led the Industrial Cooperation arm of the Canadian International Development Agency to contract Cartier Engineering to carry out an in-depth coal carbonization project in Niger. The aim of the project was to construct a coal carbonization pilot plant at Tchirozerine, to produce carbonized coal in lumps and, if possible, in briquettes, to carry out an acceptance test in a large number of families in Agadez, and to market the produce in a number of selected locations, and to study the economical feasibility of the project. Also, as a prerequisite to funding, CIDA exacted acquisition of a number of letters of intent from the Niger private sector to show their willingness to invest into a commercial enterprise and to continue the project later on if it, during the testing, would prove to be commercially viable. In fact, the local private sector showed more enthusiasm than anticipated, and over twenty participants formed a company, named SOCAREN (SARL), and invested 200,000 FCFA each in it, thus more than fulfilling the CIDA prerequisites and opening up the financing of the project, which started in the fall of 1990. -9-  RORPIJAAKKO: NIGER COAL. PROJECT REVIEW/1994 . WORLD BANK/AFTPS Sonichar joined SOCAREN investing also 200,000 FCFA with an agreement that their share would be allowed to increase up to 20% of the total in the future. 4.0 TECHNICAL REVIEW 4.1 Introduction The following chapters will review certain technical aspects. The idea is not to reiterate the data available in the final project report released in 1993, but rather to compliment it and reinforce the technical feasibility of the methods as well as offer solutions to the shortcomings any pilot plant normally has in comparison with a commercial installation. Most of the shortcomings are due to the incompatibility of certain pieces of equipment. It was caused by factors, such as the availability of equipment, project budget limitations and certain unknown characteristics of the feedstock. The project budget and time limitations necessitated compromising the equipment acquisitions to ensure that the work could be done on time and within the budget. -10-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 4.2 Feedstock Considerations 4.2.1 In Situ Quality and Quantity The raw feedstock coal is extracted from the Anou-Araren mine with standard mining methods utilised at this mine and hauled directly to the plant by dump trucks without any special preparation. The total haulage distance is about 5 km. The coal in the deposit is in two seams: Seam A and Seam B. These seams are covered by about a 50 m overburden and separated from one another by an intercalation of varying thickness and on average only about 0.2 m thick. Both seams A and B are on average 2.50 m thick according to the information supplied by Sonichar. This gives a ratio 1 to 1 of coal in seams A and B. The earlier laboratory carbonization tests indicated that the coal of seam A with its high average ash content of up to 62.8% was not very suitable for carbonization. However, the lower ash content of about 30- 40% of seam B makes it usable. The ash content values vary widely. However, the analyses carried out during the plant operation gave the average ash content value of 30% for the coal delivered to the plant. This reflects the influence of controlling the quality of coal extracted at the mine for carbonization. The overall average ash content appears to be over 40%. In fact, the -11-  KORPIJAAKXO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS Sonichar power station mixes coal from seams A and B in suitable ratios to keep the ash content of the feedstock at 49%. The total reserves in the Anou-Araren deposit are estimated at 13.7 million tonnes. The mine has been designed for a 30 year life and for an annual production capacity of 300,000 tonnes. However, for years the power station with its 32 MW capacity has operated only at 40 to 60% of its total capacity consuming only about 110,000 to 120,000 tonnes of coal per year. At the abovementioned mining rate there would be coal for the power station for more than 60 years. As also, according to some preliminary indications, the coal in seam A appears to improve in quality as the mine advances towards west, it is probable that even seam A coal might be usable for carbonization in the future. Based on the ratio of A to B seam coal (1 to 1), it appears that at today's power station consumption rate there would be about a 90,000 tonne annual reserve of seam B coal for the carbonization plant for the next 30 years. To realize this would require an increase of the mining rate to the full capacity of the mine or to 300,000 tonnes annually. As a result, there would be a 90,000 tonne annual surplus of seam A coal, if it were not suitable for carbonization. These calculations are only of magnitude of order and would require a thorough study of detailed deposit data and the required mixing ratios. In any case, they give an indication of the potential of the existing site. -12-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS The coal deposit of Anou-Araren appears to extent to the north indicating further reserves. According to other exploration projects, about 40 km north of Anou-Araren, there are large deposits of good quality coal, albeit at a depth of 400 metres, or at this time not economically minable. These deposits have been estimated to contain up to 2250 megatonnes of good quality coal. 4.2.2 Quality of Coal Delivered to the Plant Initially, the quality of coal delivered to the plant varied greatly. Quite frequently it contained large quantities of blocks of steriles and obviously material also from seam A. This created a situation, where too much time was used to remove the unwanted material by hand. Also, the high ash content caused by impurities lowered the quality of the product. Another problem was a very high content of fines in the coal delivered to the site. The kiln can handle particles down to 10 to 25 mm in size. Anything smaller creates flow problems inside the kiln and cannot carbonized. There were occasions when the proportion of the fines exceeded 80% of the total quantity delivered. To correct these problems, caused by the inferior quality of delivered coal, a more strict quality control at the mine was established. At the mine site, the operators of heavy equipment are used to loading large quantities of loosened up coal into 25 to 35 tonne trucks and only roughly separating seam A and B materials for their final mixing at the coal receiving station for feeding the -13-  KORPIJAAKKO: NIGER COAL. PROJECT REVIEW/1994 .... WORLD BANK/AFTPS power station. However, for the carbonization plant a more careful selection is needed. To ensure that only seam B material and as little contaminants as possible were delivered to the plant, an engineering geologist, who also was being trained as the Niger technical director for the plant, was present at the mine site whenever coal was selected for the plant. He directed the equipment operators to select the best quality coal for carbonization. This activity is only periodical and in relation to the total mining quantities insignificant consisting of only half a dozen truckloads a week and causing no deviation in the normal mining activity. Normally it takes only 2 to 3 hours and is easily handled by the plant engineer within his other duties and does not require hiring of a special individual. Establishment of a strict quality control at the mine site ensured a good quality feedstock at the plant site and eliminated most of the coal quality problems. The ash content fell to an average of about 30%, or in fact below the average ash content of over 40% usually measured in the coal of seam B delivered the power plant. Also the percentage of fines fell from the high of 80% to a more manageable percentage of about 40%. The initial high percentage was caused mainly by delivering coal ground up by the tracks of heavy equipment at the mine. By avoiding travelling over the coal to be delivered to the carbonization plant, more intact blocks were obtained thus reducing the percentage of fines delivered. -14-  KORPIJAARKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS Also, the calorific value of the feedstock was improved from the average of about 4000 kcal/kg normally obtained for the coal of seam B delivered to the power station to an average of up to 5400 kcal/kg. This increase is mainly due to a decrease in the ash content since the calorific value is inversely proportional to the ash content. For the overall product efficiency of the product the calorific value is not as important as it is for the power station, since the domestic cooking stoves are not any high efficiency appliances, and in actually perform best with a fuel of a relatively low calorific value. The fines are returnable to the power station and credited against the total billing, although at a discounted rate. The greatest drawback in having initially to deal with large quantities of steriles and fines is that their handling greatly reduces the efficiency of the process and adds to labour cost. 4.3 Kiln and Ancillary Equipment Performance 4.3.1 Introduction The term "ancillary equipment" refers to the equipment needed to handle the feedstock before and during loading and unloading it from the kiln as well as its handling and preparation for briquetting. The pilot plant ancillary equipment consists of three belt conveyors, one bucket elevator, two screw conveyors, one -15-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 ... WORLD BANK/AFTPS vibrating screen, one mixer, one crusher, one briquette press and an array of electrical kiln controls, Briquetting process is discussed under its own heading, since it appears that in the future a sizable proportion of the produce might come in the form of briquettes. Kiln was originally designed for a potential annual production capacity of about 3000 tonnes of carbonized coal. Most of the ancillary equipment has a capacity of up to several tonnes per hour and was believed to exceed substantially the production capacity of the kiln. Due to both budgeting and time constraints the number of conveyors was minimized from he total number required and concerning the crusher, a compromise piece was acquired. The following is a brief review of the performance of the equipment used and an explanation of any shortcomings and solution to problems that has to be taken into consideration when planning for additional equipment for a commercial operation. It should be pointed out, that at the present equipment configuration, the plant is capable of producing about 730 tonnes of carbonized coal annually, and that with very limited acquisition of additional pieces of equipment it can reach its planned capacity of 3000 tonnes. In any case, it is a pilot plant and rarely, if ever, a pilot plant can be turned into a full-fledged commercial operation without any modifications. -16-  KORPIJAAKXO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANX/AFTPS The kiln consists of the actual retort used to carbonize the feedstock. Its performance will be reviewed in the light of the performance of the ancillary equipment and the coal quality and its characteristics. 4.3.2 Ancillary Equipment 4.3.2.1 Conveyors Belt conveyors have caused no problems as their capacity is several times higher than that of the kiln and they could handle a load for a number of kilns. The limited number (3) of belt conveyors caused some delays, since they had to be moved from one location to another depending on the tasks being performed. The reason for not acquiring more belt conveyors was to optimize their number to meet the budget limitations. However, their number was sufficient to allow the kiln to run at its full capacity long enough time periods to properly test its capability and thus no handicap was created for the purpose of a pilot plant and for the expected test market requirements. The need of additional conveyors will be discussed in the chapter on the future requirements of the plant for a full- fledged commercial operation. Loading of the kiln is done by a bucket elevator. Also its capacity of several tonnes per hour largely exceeds the kiln's production capacity of 3000 tonnes per year. Initially, particles of coal up to 65 mm in diameter were carbonized. However, the buckets of the elevator are slightly too small to handle this size and the -17-  KORPIJKAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS material tended to get stuck in the system. As in addition to this it was observed that the optimal maximum size of blocks that performed efficiently in the local stoves was 45 mm, the maximum size of particles was reduced to 45 mm. This adjustment remedied the handling problem. In case larger particle size is needed, it can be achieved simply by acquiring a larger sized bucket elevator. The kiln was designed to be emptied by a continuously operating screw conveyor. During the operation it became obvious that this method of discharging the produce was not suitable if the produce was to be in the form of intact blocks, since it tended to grind up a large proportion of the carbonized coal. In fact, up to 60% of the produce was less than 25 mm in diameter, or below the minimum size the local stoves could efficiently handle. The increased amount of fines would require a larger portion of the produce to be briquetted resulting in a more expensive but a more convenient and homogenous fuel. Because of this shortcoming, the screw conveyor was replaced by a manually operated double door mechanical discharge system designed and constructed at the site by the operating crew under the supervision of the project manager. The manual discharge system reduced the portion of the fines to about 35%. -18-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS A screw conveyor is usable, if a larger portion of briquettes is required and is a viable option for the future depending on the market preferences. The second screw conveyor, used to convey the fines to be briquetted from a storage bin into the mixer, operated without any problems. 4.3.2.2 Screen and Crusher The coal delivered from the mine to the pilot plant site is composed of a material of a large variety of grain sizes from fine dust to blocks measuring up to half a meter in diameter. Originally, the material was passed through the power station's first stage crusher to reduce it to a size of 100 mm or less. However, this process produced too much fines not usable for the carbonization process and was discontinued. The largest blocks, up to almost one metre in size, are manually broken into smaller ones before screening. Since they comprise only a small percentage of the total, and are relatively easily broken into smaller size, they have not caused any appreciable delay or manpower problems during the pilot plant operation. For the industrial phase a crusher capable of crushing particles up to 0.5 m in diameter to 45 mm or less, but not producing too much fines, is needed to assure a continuous and rapid flow of feedstock to the kiln. For the pilot plant stage, a small crusher was acquired, but it also produced too much fines at this stage where briquetting was not carried out at -19-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANKJAFTPS a full-scale and its use was discontinued for raw material crushing. The raw coal and the manually crushed particles are fed manually onto a conveyor belt for screening in a double deck screen. The screening is done through 45 mm and 25 mm screens. Presently about 35% is passed through as smaller than 25 mm and is stockpiled for the return to the power station and credited against the total bill. This portion will be carbonizable only after a suitable crusher is acquired to allow its grinding into fines less than 6 mm in diameter. These fines can be first briquetted and thus formed raw coal briquettes carbonized. The process is described later in the chapter on briquetting. About 10% is oversize, i.e. more than 45 mm in diameter and is again manually crushed for further screening. The rest, about 60% is carbonized directly. The same screen is also used to screen the produce to separate the fines from the usable fraction. The intention was to alternate the screening of the raw coal and the produce and keep the kiln producing continuously. However, due to the large quantities of fines, the screen has proven to be too small to allow a fast enough screening of the raw material to stockpile it for to last a long enough time to allow screening of the produce while the kiln continues operating. As a result, once the small stockpile of screened feedstock is depleted and the screening of produce continues, the kiln has to be shut down until -20-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANKVAFTPS enough raw material has been screened again. From this it may appear that the kiln produces batches, although actually during the process cycle its operates continually as planned. The remedy for this pilot plant shortcoming is simply the acquisition of a screen(s) large enough to handle all the screening requirements and the acquisition of a suitable small size crusher(s) to crush both incoming feedstock as well as any fines (raw or carbonized coal) destined to be briquetted. 4.3.2.3 Kiln Controls The process (carbonization) control is done partly manually and partly by semi-automatic controls. Controls include a number of thermocouples to monitor the temperatures in various sections of the kiln. The temperatures are kept within certain limits to ensure a proper degree of carbonization and to avoid any excessive combustion of the feedstock in the kiln. Some combustion is needed, especially in the early stages of the carbonization process, and occasionally during the process, if the temperatures fall below the exothermic reaction level (about 2800 C). The temperatures in the chimney and in the main body of the kiln are monitored by a six-channel chart recorder. The control is performed by using automatic temperature controlled airflow valves and manually adjusting the chimney damper to control the draft and the exhaust gas temperatures which are a good -21-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS indicator of the process conditions. The control is also done by adjusting the speed of production according to the carbonization temperatures and the residence time in the kiln. All these adjustments are made in response to the same-day analytical results on the volatile matter content of the produce. The cooling zone of the kiln is used to precool the product by injecting water inside the cooling zone of the kiln and by cool water circulating in the double-walled discharge mechanism. Further cooling is done by spraying the hot product by water whenever necessary and by letting it cool some time in the receiving containers to ensure that no spontaneous combustion takes place. By using simple low technology for the controls it is ensured that the operation is easily run in the local conditions without any expensive and complicated high technology equipment that would make the operation dependent on the outside expertise and would cause operating and cost problems. There have been no problems with control mechanisms. Certain small adjustments would be made in the materials and mechanisms for a larger scale industrial operation. 4.3.3 Kiln Performance 4.3.3.1 Production Capacity The existing pilot plant kiln was designed to be able to produce about 10 tonnes of carbonized coal per day, or about 3000 tonnes per year. During the testing, production rates of up to 625 kg per -22-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .WORLD BANXKAFTPS hour were reached equalling 10 tonnes per day while working two 8 hour shifts. Based on this rate, a production rate up to 14 to 15 tonnes per day could be achieved, if the work would be carried out 24 hours continuously. Taking into consideration downtime, it is assumed that the plant could work 300 days per year. At a rate of 10 tonnes per day, the total annual production per kiln would be 3000 tonnes as was originally planned. For a number of reasons, such as untrained crew, insufficient ancillary equipment (screen) capacity and minor equipment breakage and the overall pilot nature of the installation, the theoretical capacity of 15 tonnes per day (equivalent of 4500 tonnes per year) was not achieved. However, maintaining the 10 tonnes per day rate was feasible at the pilot plant configuration for short periods of time and 7.2 tonnes per day over extended time periods. It appears technically possible to attain up to a 4500 tonne annual production by optimizing the ancillary equipment. Initially, a screw conveyor was used to discharge the carbonized product from the kiln. However, it was quickly discovered that the screw had a tendency to crush the product resulting in production of up to 60% of fines. At this stage they were not briquettable in any large quantities because of the lack of a suitable crusher to reduce their grain size to the required 6 mm maximum size. Thus only about 40% of the total product was usable in practice. The installation of a manual mechanical discharge mechanism reduced the percentage of fines down to about 35 to 40% bringing the usable -23-  KORPIJAAXXO: NIGER COAL. PROJECT REVIEW/1994 ... WORLD BANX/AFTPS production rate up to about 5 tonnes per day for each operating day. This equals 1500 tonnes per year of total production if the plant could operate the planned 300 days per year. However, due to the inefficacy of the screening system, it was possible to produce only about 20 day continuously and then shut down the production for about 30 days to screen the produce and feedstock. This cycle could be repeated 7.3 time in a year. Thus the actual equivalent capacity of usable production, that is carbonized produce above the size of 25 mm in diameter, was about 730 tonnes. It was slightly larger since small quantities of the fines produced were successfully briquetted. All this shows, that the kiln is capable of producing at a production rate equalling a total 3000 tonnes of carbonized coal annually when operated on two shifts and up 4500 tonnes on three shifts, but at the present combination of equipment this level is reduced to about 730 tonnes of usable produce per year. It also shows, that actual usable production rate can be raised to the planned level by the acquisition of a few pieces of ancillary equipment to step up from the pilot plant level to a proper industrial level. While one kiln is capable of producing even up to 4500 tonnes per year, two kilns would be required to ensure an uninterrupted production to ensure a stockpile of produce in case of any technical or other production problem. The cost, however, would not -24-  KORPIJAAKKO: NIGER COAL. PROJECT REVIEW/1994 .... WORLD BANK/AFTPS be doubled because only a few additional pieces of equipment would have to be added to the existing full compliment of ancillary equipment to keep two kilns operating. Also it is foreseen, that having two kilns, it could be possible to extend the effective equivalent one kiln operating period of 300 days to 365 days per year and thus easily ensure at least a 3000 tonne annual production rate. 4.3.3.2 Kiln Performance Considerations Carbonization of wood and other biomass materials is an ancient technique to alter the nature of fuel. Techniques vary from small earth mound kilns, with an annual capacity of few hundred kilograms and a 5 to 10% yield, to huge multimillion dollar high technology plants with a capacity of 100,000 tonnes or more and yields up to 80%. While the high technology plants may look attractive in an industrialized country, they pose both unsurmountable financial and technical problems to most developing countries and thus not feasible for their needs - at least in the first stages of developing the techniques and markets. For these reasons Cartier Engineering developed a technology that is at the same time simple and cost effective and can be handled both technically and financially by the targeted region and which also attains a good yield thus increasing economy and is environmentally friendly as well. High yield translates into saving -25-  KORPIJAAKKO: NIGER COAL. PROJECT REVIEW/1994 .... WORLD BANK/AFTPS natural resources, reducing pollution and cost of raw materials and their transport to the plant. The kiln designed by Cartier Engineering has been locally constructed, albeit from imported materials since it is made of steel. Steel construction was selected over the bricks used in the first kiln (in Burundi) which was built from locally made bricks. The main reasons are the durability and low maintenance requirement of a steel kiln and the ease and accuracy of the process control. The brick kiln had proven to be more difficult to control, mainly due to it not being airtight enough to ensure proper conditions for a pyrolysis and to avoid combustion of the feedstock. Steel kilns can be manufactured in sections in one location and transported to the plant site, making their construction more efficient in case a number of kilns in a number of locations are needed. For instance, the Niger project kiln was constructed in Niamey and transported by a truck to the site where it was erected and finished to its final readiness. The performance of the project kiln is affected by the quality of the feedstock and, to some extent, by the ambient temperature as well as the direction of the prevailing wind. As to the quality of the feedstock, its grains size is of importance in achieving proper level of carbonization. A number of tests were carried out on different size fractions to determine the -26-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS limits within which the kiln was capable of producing homogeneous product. The tests revealed that this kiln can carbonize size fractions down to about 15 to 22 mm in size. When the size was diminished to contain particles less than 10, it was observed that the fines tended to start agglomerate and form large agglutinated chunks of coal, which then often got attached to the walls of kiln and impeded the flow of feedstock. This increased the residence time and eventually led into both over-carbonization and combustion of the feedstock. As a result, the percentage of volatiles dropped to very low of 3-4%; far too much below the preferred level of 7 to 8% and thus too low for the produce to be used as a domestic fuel, since at such a level it is very difficult to light and does not sustain continued combustion in the stoves. Also its ash content rose to 50-60% and in many cases the product was a mixture of highly carbonized coal and chunks of burned out coal. As to the maximum size, there were no problems carbonizing fractions up to 60 mm in size. The only limitation was caused by the bucket elevator which does not easily accommodate particles over 55 mm in size. Since the local cooking stoves perform best on the fuel between 25 and 45 mm in size, the operation was limited to this fraction. Control of the temperatures in the kiln is very important for the process to progress properly. Both the carbonization temperature and the speed are the principal factors controlling the process. -27-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS With the steel kiln it was possible to control the temperatures accurately enough to be able to produce quite uniformly carbonized produce. Only the fluctuations in the ambient temperatures and the direction and the force of the wind created variations in the internal temperatures in the kiln and had to be taken into consideration when controlling the process to avoid either over- or under-carbonization. Before the produce is discharged from the kiln it enters the so- called cooling zone of the kiln. It is located below the carbonization zone and is the section which is not clad with refractory cement on the inside as is the rest of the kiln. The simple steel wall allows a large heat loss and essentially stops the process and starts to cool down the product. At this stage cooling is enhanced by injecting water into the produce inside the kiln and spraying on the outside. Initially, only this method was used. However, due to air leaking into the kiln thorough the discharge mechanism, it was improved by enveloping it with a double wall allowing the entire mechanism to be cooled down. This improvement solved the cooling problem and also allowed the reduction of the quantity of water needed from about 300 m3 per month to about 100 m3 per month. The consumption can be further reduced to a negligible quantity for the industrial stage by recycling the cooling water - an important consideration both for environmental (no discharge of water, water resource conservation) and economical (cost of producing water) reasons. -28-  KORPIJAAKKO: NIGER COAL, PROJECT REVIEW/1994 .... WORLD BANK/AFTPS 4.3.4 Product Review 4.3.4.1 Chemical Characteristics A total of 342 samples of product were analyzed in a laboratory to determine the basic chemical characteristics of the produce. The most important characteristics are given in Table 1 below. The values both for the product and the feedstock as well as the change (