Chapter thirteen: Biogas programs in developing countries

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Experience with biogas in China
Potential of biogas generation and biogas digester construction
Biogas utilization
Effluent utilization
Economic aspects
Financial support
Training in biogas technology
Organization of the biogas sector
Potential for biogas generation and digester construction
Experience with biogas in India
Biogas plants
Biogas production
Use of biogas
Utilization of effluent
Cost of installation
Annual costs and savings
Financial assistance from government
Organization of the biogas sector
Organization of energy sector
Utilization of effluent
Costs and benefits
Research and development
Experiences with biogas
Installations
Effluent utilization
Costs and benefits
Experiences with biogas
Organization of the biogas sector
Africa

 

Most countries became aware of biogas technology by the middle of the Twentieth Century. However, real interest in biogas was aroused from 1973 onwards, with the onset of the energy crisis, which drew general attention to the depletion of fossil fuel, energy resources and the need to develop renewable sources of energy, such as biogas. The importance of biogas as an efficient, non-polluting energy source is now well recognized.

International organizations like the Economic and Social Commission for Asia and the Pacific (ESCAP), the Food and Agriculture Organization of the United Nations (FAO), the United Nations Industrial Development Organization (UNIDO), the World Health Organization (WHO) and the United Nations Environment Program (UNEP) have done considerable work in disseminating and developing biogas technology

Afghanistan Biogas development has been initiated through a UNDP- supported biogas demonstration project. It has been proposed that demonstration plants be set up in each agro-ecological zone. Based on the experience obtained with the demonstration projects, extension programs will be undertaken.

Bangladesh Although research and development work on biogas has been undertaken since 1973 by the Agricultural Universities, little headway has been made in implementation of the programme at the field level. A few demonstration plants have been installed. Bangladesh Agricultural University organized a training course at Mymensingh during 1981 with the assistance of UNESCO. Many of the plants so far set up are of KVIC design. However, experiments are being carried with fixed dome models. A comprehensive developmental plan, which would involve UNEP assistance, has been drawn up, in view of the urgent need to replace firewood as fuel.

Bhutan The first large-scale program was begun in 1987, through cooperation between UNICEF and the Rural Energy Division. Fifty- four 2 m3 and 3 m3 fixed dome digesters were built in 1988 and are functioning satisfactorily.

Burma (Union of Myanmar) Even though Burma is self-sufficient in fossil fuel and firewood resources, deforestation, inadequate transportation infrastructure in certain areas, and the anticipated increase in the demand of energy sources have necessitated taking up measures for the development of alternative and renewable fuel energy sources. Research on various aspects of biogas technology has been conducted by the Central Research Organization for the last 10 years. The Agriculture Mechanization Department of the Ministry of Agriculture and Forestry is one of the main institutions involved in the development of a programme. The Department has developed a semi-industrial type biogas digester with a m capacity of 50 1/day. In 1981 six continuous floating drum type digesters were constructed on cooperative and meat producing farms. About 40 floating drum digesters were constructed in 1982 in model village No. 1, near Rangoon. The Biogas Production and Utilization Centre was established under the Ministry of Agriculture and Forestry in 1983 to coordinate research and implementation of biogas technology. It is planned to cover 500 villages in 10 states under the biogas development project.

The target of 2000 family units was set in 1990, for which 14 construction teams (one for each State or Division) are available.

China China has a total area of about 9.6 million km2 and a total population of 1.100 million. The population growth rate is at about 1% per year. There are about 900 millions peasants in rural areas and some 60% of the total population is engaged in agriculture. About 34%. of the total area is under cultivation. The forest area is about 14%. During the last two decades, the forest area has been increased by 11 million ha.

There are about 130 million cattle and draft animals, 260 million pigs, 170 million sheep and goats and some 1,400 million poultry in China. The farmers keep on Average 0.3 cattle units (500 kg live weight) per ha. Energy consumption in 1984, in rural areas, was some 370 million tons Coal Equivalents, around 40% from coal and 60% from biomass (straw and firewood). This corresponds to 230 million tonnes of straw and 180 million tonnes of firewood. Another estimate gives a consumption of 400 million tonnes crop stalks and straw, burned annually as domestic fuel. It accounts to some 80% of rural domestic energy consumption. In addition, 70 million m firewood is burned annually. The productivity of woods and forests is 120 million tonnes firewood only, leaving a deficit of 60 million tonnes annually.

 

Experience with biogas in China

China has learned many lessons during the recent past. After 1975, slogans such as "do it in a big way" or "biogas for every household" led to the construction of 1.6 million digesters annually, which were very cheap (Yuan 20 - 30) but of low quality. In 1980, over 50% of all digesters were found to be defective and were not in use. The consequence was that in 1979, the policy was changed to "strengthen leadership, popularize positively, develop in a batch way, advance steadily". Construction activity slowed down to less than 1/3 of the previous one. Attention was paid to combine quantity with quality to reach a consolidated development. In this period, 95% of all digesters constructed were flawless and the utilization rate was above 85%. The measures now have to be matched to the local conditions. Climatic as well as social and cultural conditions are being studied first before digesters are being introduced. Not all places are suitable for biogas. In the Sichuan Province, digesters are constructed mainly in those areas where there are no small power stations, coalpits or possibilities for planting fuel wood. It was also learned that the popularization of BG would only be successful when the direct benefits to the farmers are obvious. To raise the direct benefits, PBTs help in comprehensive utilization of residues. Thus, a digester is the key to integrated farming systems. People recognized that management is the key to success because the development of BGT in the long term. There are many management tasks to be done in preparation, construction and operation of digesters (policy development, proper design, organization and financing of training and extension services, material supply, rewarding etc.). The rapid economic development in rural areas has brought along some new problems to the biogas extension work. More and more coal pits have been set up, while rice yield, and thus straw harvests, increased also. The peasants are not so eager any more to construct digesters because of easy access to coal. More and more peasants set up small individual enterprises, abandoned farming, and thus lost the prerequisite for a digester. Additionally, market prices for e.g. cement increased and part of the cement has to be purchased from the market. Not all farmers can be supplied with levied cement. Although quality of digesters and benefits of operation have been improved greatly in recent years, the speed of development is low.

 

Potential of biogas generation and biogas digester construction

Chinese peasants use a wide variety of substrates, such as straw, night soil and, manures as a substrate for the biogas process. Different sources estimate that the total potential of biogas plant is from 145,000 - 62,000 million m3 biogas (45% from animal manures, 5% from night soil and 50% from straw and stalks). This would be equivalent to the total energy demand of rural households for cooking and lighting. Only 2.5% of this potential is actually being produced by about 9/million digesters today. Gas production ranges from 0.20 - 0.25 m3/kg TS, or 0.1 - 0.15 m3 /d. In rural areas, where water is scarce, or where people are used to handling dry manure, the dry-fermentation technique is popular. Preparation of feedstock differs slightly. The gas production is above 0.2 m3 / per kg TS added, and 0.2. m3 per day.

The total potential for biogas plants may be compute] from the potential of biogas divided by annual production of 300 m gas, which results in some 200 million digesters. At the current construction rate of about 500,000 digesters per year, it would take more than 400 years to exhaust the market. For the time being, biogas plants have been constructed in 16 out of 28 provinces. The climatic conditions in the other provinces are less favourable, and the impact on the total potential for digester construction would still have to be assessed. The purchasing power of farmers seems to have only a small influence.

At present, there are about 5 millions family sized fixed dome plants of 6, 8 and 10 m volume operating in China, 50,000 red-mud-plastic (RMP) digesters of over 10 m3 and the target is 400,000 - 500,000 of the small household digesters and 25,000 for medium and large-scale (farms, distilleries etc.) annually. Even though China has the largest construction rate of all countries in the region, it is slow compared to the huge potential. The new attitude is to develop positively, pay attention to both construction and especially to management, and to seek practical benefits. Sound work and quality in construction are emphasized. Construction of family-sized fixed dome digesters is well advanced, and already standardized at national level. Sound experience is available regarding properties of construction materials, technique and design. Construction material and technique are selected at the site (e.g. brickwork, lime-mortar, cement-mortar, concrete cast-in-place etc.) to keep costs low.

 

Biogas utilization

The gas is used by about 25 million people for cooking and lightning, for 8 - 10 months a year. Many rural households are equipped with both bilgas stoves and improved cooking stoves. With the latter type, the peasants burn straw and wood as usual during the winter months for cooking and heating. Improved and cheap biogas stoves and lamps have been developed, and are distributed to every biogas owner. The cost of one biogas lamp varies between 6 12 Yuan. Lamps and burners are adapted to low pressures of about 2 cm, at which RPM digesters operate. Commercial and industrial burners are also being investigated in China. Furthermore, the use of biogas is manifold: there are about 400 biogas power stations, with a total capacity of 5,800 HP. 800 biogas electric stations, with a total capacity of 7,800 kw, provide electricity to over 17,000 households. Thus, China has solid experience in running diesel and gasoline engines with biogas.

There are numerous agricultural applications, such as crop drying, tea baking, egg hatching, cultivation of rice seedlings and mushrooms, etc. Catalytic infrared radiators, hatcheries, refrigerators and air conditioners with automatic control have been developed and are used.

 

Effluent utilization

Whether the biogas plant of the anaerobic process can survive depends on its benefits over and above the biogas produced, especially on its comprehensive benefits. Benefits from effluent have been given high priority in China and the utilization of residues has a bright future. Through the digestion of straw, a high amount of fertilizer is conserved in China. More than 90% of N. P. and K are located in the sludge of digested manure.

The residues are used in agriculture, aquaculture, for growing edible fungi and for raising earthworms. Top dressing is recommended in some provinces. The yield increase of crops was found to be higher using digested slurry than with chemical fertilizer alone. Soil fertility (stable humus) increased, as well as soil porosity and water retention capacity. Rice yields increased by 11 - 14% compared with control. Fish yields were 25% - 50% higher than when fed with pig manure directly. Mushrooms could be picked 3-7 days earlier and the yield increased by 6%. The residues after mushroom cultivation still has fertilizer value. It is estimated that every 8 m biogas plant can provide the medium needed for 55 m of mushroom culture. Raising earthworms is becoming popular in China. For example, there are 550 specialized households engaged in earthworm raising in Jiangsu Province.

Various kinds of equipment are used to remove the slurry from the digester, to transport it to the fields and to apply it. This is done about twice a year, after the wheat harvest and the rice harvest. According to the different fermentation methods, the residues have different total solids contents, and are adapted to the local customs of application of organic manure.

 

Economic aspects

Construction costs vary by about +100% depending upon the location. In recent years, prices have increased considerably: from 1983 - 1986, the price for cement increased from 40 Y/t - 100 Y/t, for steel from 500 Y/t - 1,100 Y/t, and for sand from 15 Y/m3 - 20 Y/m3 . The price for gasoline is now 1.1 Y/l, for diesel 0.5 Y/l, and for electricity 0.15 Y/kWh. Today, a farmer has to invest 250-300 Yuan for a 6 m3 digester, with a service life of about 20 years. At this size, the cost per digester volume is about 42 - 50 Y/m3 or about US$ 12/m3. There is an economy of scale effect, i.e. each m of larger digesters becomes cheaper to construct. The construction charge is about 40 Yuan (4 Yuan per man and day). Thus, the labor charge contributes only a small fraction of the total cost and in many villages the farmer can construct the digester by himself, with the instruction of the people from BGT offices. There is a guarantee for quality, over a 5 year operation period.

 

Financial support

The policy of the Chinese Government is "emulating through consolidation, developing positively, paying attention to both construction and management, hence seeking for practical benefits" and the principle of "taking construction by farmers themselves as a mainline, and state and collective support as an aid". The Biogas Service Companies (BSCS) have, in general, to rely on themselves, and near and around cities profits are possible. Those companies without profit will receive subsidies from the County Government, which has special funds for extension, development and demonstration at its disposal for community digesters. In Chungdu County, BSCs receive Yuan 20,000 - 60,000 regularly as a subsidy. The investment provided by the Central and Local Governments on biogas construction is several tens of million Yuan per year. In the Sichuan Province for example, the Government allocated Yuan 49 million for the development of biogas from 1973 - 1984. A considerable sum of investment comes from collective economic organizations in the countryside. Low interest or State subsidized loans have been given by the agriculture bank to the farmers who have difficulties building digesters. Several BGT people at the Biogas Service Office in Chengdu install Biogas plants in Ta Xin Township and other places: the work of the Office has been profitable enough to enable them to buy a restaurant nearby with the money earned from building improved septic systems in many dormitories around Chengdu.

Special support is provided to community digesters. One important example is the plant near Shenyang. The total cost in 1983/84 was 260,000 Yuan, and 80,000 Yuan of it were spent on 5,200 m of gas pipes. The main pipe has a diameters of 17 cm. The income is 60,000 Yuan per year and the calculated payback period is 6 - 7 years. It would be even much shorter if the distillery would have replaced all its fuel consumption, because the price for industrial coal is twice of domestic coal. Under this condition, the subsidy of 50% by the local Government and 25% of the village Government would not have been approved. Thus, the 400 villagers only paid 25% of the investment, about 100 - 200 Yuan per family. A connection to the natural gas pipeline system would require an investment of Yuan 1,600 per family. In the Chengdu vicinity, a poultry farm where BRTC has built a demonstration digestion system (2 x 50 m3) in a family-owned chicken farm with 20,000 layers exists. The family invested Yuan 40,000 in the system, in addition to the subsidy they received from the government. The biogas is used for cooking, lighting and to heat the hatchery. The digested slurry is used in part for the fish pond, and the rest is given to farmers as organic fertilizer.

 

Training in biogas technology

Training courses at the highest level are conducted at BRTC in Chengdu since 1981, for staff members of Biogas Offices, up to provincial level. 2 - 3 courses are given each year, with 50 participants in each course. The duration is 50 days per course. Training comprises "training of trainers" and of "workmen". More than 1,000 people have been trained. Workmen are responsible for extension and organization of development work, and for information and management. Technicians will become trainers in Biogas Offices. Biogas Offices at (and above) County level hold courses for 30 - 60 days. After that, the trainees have to join a Construction Team for half a year. These trainees will later work in other Construction Teams. Peasant Biogas Technicians (PBT) receive a theoretical training of 30 days only and a shorter practical training. All technicians receive Biogas Technician Certificates when they passed the examination. Training in new technologies has also regularly been given to PBTs who already got their certificates. In the Sichuan Province, 200,000 peasants and cadres have received basic training since 1973. 6,000 PBTs are now working in the countryside.

Bio-energy and rural energy is taught as specific subjects in 4 colleges and 4 specific middle schools. The Department of News and Propaganda (radio, TV, newspapers, magazines) is spreading information and thus training at a popular level.

Moreover, the BRTC in Chengdu gives international training courses. Since 1982, 5 courses with 98 participants from 38 countries have been held. Most of these participants, who have been trained for 4 to 6 weeks, play an active role in BGT in their home countries. The development of scientific research in BGT has enhanced extension and dissemination. Intensive research has been done on construction and on design (application of technology), in which 13 organizations were involved. Current activities focus on design of medium and large scale digesters (100 - 500 m volume). The Chinese Academy of Science is also involved in R & D projects. Other areas of research are on:

(a) fermentation techniques;
(b) comprehensive utilization of biogas and residues;
(c) new materials (RMP);
(d) basic theories on BGT;
(e) gas utilization.

 

Organization of the biogas sector

Construction of the digester is the basis, while management is the key to Biogas development. The great attention and strong support by the Chinese Government are the key factors for rapid biogas development in China. The overall coordination is under the direction of the State Science and Technology Commission (SSTC) and the Ministry of Agriculture, Animal Husbandry and Fisheries (MAAHF). This is shown in Figure 13.1 below. Some 100,000 people work in the whole scheme of biogas technology (BGT). The SSTC itself has 14 Departments, with 400 staff members and 17 affiliated organizations with 4,600 staff members. Two of the departments are concerned with energy: the Department for Industrial Technology (BIT) and the Department for Scientific and Technological Information (DSIT). Energy is one of 5 fields of activity at DIT, and is subdivided into Conventional, New and Renewables Sources of Energy. The functions of this Division are policy and legislation, planning, management, information and international cooperation. Among the affiliated organizations, the ISTIC (Institute of Science and Technical Information of China) and "Chonquing Branch, Institute of Scientific and Technical Information of China" are engaged in BGT. The Science and Technology Commission has offices at Provincial and Municipal Level. It maintains Municipal and local research institutions. All research institutes were set up recently (1984-85). The "Liaoning Province Research Institute of Energy Resources" (LPRIER) was set up in 1985. It is to develop, demonstrate and extend new sources of energy: Solar (PV and thermal), Biogas (semi plastic or red mud plastic (RMP) and industrial plants) and Fuel Alcohol (from sweet sorghum). The organizational chart is given in Figure 13.2 below.

Figure 13.1: Chart on overall organization of the biogas field in China

Figure 13.2: Organization chart of "Livening Province Research Institute of Energy Resources" (LPRIER)

It is associated with three other institutions. All together there is a staff of 130 people, with over 70 people with technical qualifications. Biogas research is conducted for processes at industrial scale (distilleries). The institute also assists the activities in dissemination of RMP digesters (semiplastic digesters) of the associated institutions. The main activity, however, is R & D into equipment and its dissemination, to make use of solar energy. The institute is highly interested in giving international courses and seminars on new and renewable sources of energy.

The MAAHF is in charge of training, dissemination, extension and applied research on Biogas technology.

Biogas Offices (BO) are in charge of management, of training, of construction (selling building materials) and of extension. Biogas Service Companies (BSC) consist of qualified construction teams, with varying numbers of technicians and work under the leadership of the BO

BOs at and above County level are authorized to train technicians. By the end of 1984, there were 25 BOs at provincial and, municipal level, 592 BSCs above County level, 1,240 BSCs (stations), and numbers are growing with the population of the biogas technology. below village level, 8,854 construction teams total staff of 10,000 and 40,000 peasant biogas technicians (PBTs). Municipal Biogas Offices are responsible for cities, and construct digesters to treat night soil, slaughter house wastes, distillery wastes, dairy farm manure etc. Country level BOs are responsible for about 10 townships. Each township has about 50 villages with about 10 teams. There are about 70 families, with 3 - 4 members per team. Bach team has its own Peasant Biogas Technician (PBT), who takes care of repair and maintenance of digesters. He may construct digesters as well. The relationships such men have with the farmers is what enables the whole system to work.

Research and training at National level is conducted by the Biogas Research Institute in Chengdu, Sichuan Province. This Institute was established in 1979 with the approval of the State Council. To date, the Chinese Government has invested more than Yuan 10 millions. The annual budget is about Yuan 700,000. UNDP has provided equipment for over US$ 400,000. The Institute has a total of 150 members, of which 100 researchers are at college level, with 19 different professional qualifications.

Since 1982, 5 international Training Courses, with over 100 participants from 40 countries, have been held. This activity was sponsored by UNDP and FAO, the first course also by ESCAP. Since 1981, 12 national training courses have been held with more than 1,000 participants. Thus, the BRTC institute plays an active role in national and international development and implementation of Biogas Technology.

The main tasks of the BRTC Institute and Centre are:

(a) To undertake research on BGT and use of biogas for rural agricultural development and other fields, in order to provide cheap energy for peasants;
(b) To coordinate concerned United Nation Organizations for international biogas courses, and especially to train technicians in Asia and the Pacific;
(c) To collect information, disseminate and publish (China Biogas Quarterly), in order to serve as a centre for Biogas Information Network and publish the academic journal "China Biogas" in coordination with the China Biogas Association;
(d) Design and construction of medium and large size plants in China and abroad (distilleries, large farms systems and sewage treatment) and the coordination and control of national R & D in BGT.

The chart in Figure 13.3 gives an overview on the structure of the China Biogas Research and Training Centre Institute (BRTC), which is to conduct international training courses and uses the existing facilities.

Figure 13.3: Organization chart of the Biogas Scientific Research Institute and Associated Institutions

Today, there are more than 60 research institutes, universities and 60 local biogas experimental stations in China, with over 1,000 research staff involved in Biogas research. The number of people involved in BG extension work amounts to about 10,000 people. Thus, a biogas management system has been formed nationwide .

Marchaim, in his recent trip to China in (November 1990), visited a Regional Biogas Office of Nanjing suburban area. It has burners and equipment needed for biogas utilization and a staff of 4 people to serve the region. He found that they are very well acquainted with the technology and have good relations with every farmer in the region who has a biogas system, adjoining the pig pen and the adjacent latrine. Much attention is paid to direct and indirect benefits. They, too, estimated that the indirect (social) benef its are 3 times higher than the direct ones.

India India has a total population of about 800 million people, of whom 80% live in rural areas in some 576,000 villages. About 70% of them are landless. There are about 237 million head of cattle, under the ownership of approximately 52 million households: of these, 57% own 1 - 3 head of cattle, 27% own 4 - 6 head, 8.7% own 7 - 9 head and 6% own above this number.

According to rough estimates, 50% of India's total energy comes from non- commercial sources, upon which the majority of the rural population survives. These include: firewood (65%), dung cakes (15%) and agricultural wastes (20%). On average, these items cover 84% of rural household energy requirements (Maulik 1982). Between one third and a half of all recoverable cattle dung is burned as fuel. The annual requirement for firewood has been estimated as 133 tonnes. Total annual production (from recorded sources) is 49 million tonnes, leaving an annual deficit of 84 million tonnes (Vimal 1985).

 

Potential for biogas generation and digester construction

The only fuel available for family-sized digesters is cattle dung. This facilitates the assessment of potential, but on the other hand, it restricts the use of biogas to cattle-owners . the assumption that 4 head of cattle are required to generate 2 m3 gas (the cooking needs of a rural family of 8), there is a potential for 22 million digesters, though when cost to the family is taken into consideration, the maximum potential is 10 million plants, representing 19% of cattle-owning families. Given an average capacity of 4 m3 gas per day, 40 million m3 could be generated daily. This would involve about 71 million head of cattle (10 kg dung per day, 20% or 0,28 m3 gas per kg total solids, about 30% of India's total cattle population.

Latest estimates by the Advisory Board on Energy give a figure of 16 - 22 million small biogas units in the country, on the assumption that 75% of all manure is available (Khandelwal and Mahdi 1986).

 

Experience with biogas in India

Activities have gained momentum since NPBD was launched in 1981 and DNES in 1982. Today, it is generally accepted among richer farmers that a biogas plant is desirable. The earlier period was taken up with problems, such as convincing bankers to give loans and setting up the organizational structure, subsidy system, etc.

Problems which arose can be classified as follows:

(a) design faults;
(b) construction faults (unskilled builders or poor materials;
(c) difficulties of financing (obtaining bank loans and delays in subsidy payment);
(d) operational problems due to incorrect feeding (often the result of over-sized digesters, a status symbol) or poor maintenance;
(e) organizational problems arising from the differences of approach and lack of coordination at the three levels of agency.

Lack of monitoring and surveys may lead to problems in the future. Alternative fuels to cattle dung must be found. The tendency to buy oversized digesters as a status symbol reduces the gain to the user. It is clear that benefits derived from the effluent are 2 - 3 times higher than the direct benefits of biogas, though this and other points are assumptions that are not backed by proper research.

 

Biogas plants

Up to 1986, a total of 642,900 digesters had been built: in 1985/6 alone, the total was 185,800. In view of the huge potential, targets have been gradually increased. Construction capacity almost doubles each year. At the current capacity, it would still take 50 years to saturate the market. However, this biogas programme, together with others (e.g. wood-saving stoves) has to compete with the pace of deforestation and other environmental hazards.

Community and Institutional Biogas Plants (IBP) are being constructed in India. Poor farmers and low castes are supposed to be involved and to participate in operation of Community Plants (CBP).

 

Biogas production

In order to adapt KVIC digesters to the various ambient temperatures, from south to north, they are designed for three different retention times to produce the same volume of gas. For the Janata type, this adaptation has yet to be approved by DNES. There are no long-term comparative tests on gas production of the two models.

 

Use of biogas

The gas is commonly used for cooking and lighting. There are a number of enterprises in each State that produce stoves and lamps. At some CPBs and IBPs biogas operates engines or agricultural equipment. Only three enterprises in India manufacture or adapt diesel engines.

 

Utilization of effluent

The effluent is usually dried in the sun, either separately or in combination with agricultural wastes. Partial composting is performed, after which it is applied to the fields in a solid state. There is no information on how widespread the use of effluent is, how it is applied or in what quantities.

A study comparing its use with that of fresh dung, for various purposes, has been undertaken (Myles 1985), basing values on average prices as of October 1985. It was found that the sale value of digested spent slurry, scientifically composted, is 8 times higher than that of fresh manure sold to the owner of a digester.

 

Cost of installation

Cost of installation varies according to type and size of the plant, increasing by about 65% between 1981 and 1986, or about 13% per year. There are also variations from State to State and District to District. There is an effect of economy of scale in both digester types. A comparison of cost may be made on the basis of cost per m of digester volume. For the same hydraulic retention time (HRT), the Janata plants are cheaper by 33% or more than KVIC digesters. The system of financial assistance is discussed below.

 

Annual costs and savings

Annual costs though depreciation, interest on loans, maintenance, repairs, overheads and labor costs have been calculated comparatively for digesters of 2 m gas/day for KVIC and Janata models (Myles 1985). In the first 5 years, annual costs amount to Rs 2,480 for a KVIC model at 40 days HRT, and Rs 1,770 for a Janata plant at the same HRT, the latter model costing Rs 1,920 for the 55 days HRT type. On the other hand, annual savings through replacement of kerosene by biogas, and fertilizer by composted effluent, yield a marginal annual gain in the first 5 years. Thereafter income and profit are dubious: first, calculations are made on the assumption that kerosene is used as fuel, when wood is more common, and secondly, there is a tendency to buy digesters larger than necessary. Furthermore, figures on income and profit are based on the subsidy given to the farmers.

 

Financial assistance from government

At present, DNES provides financial assistance to:

(a) purchaser's subsidy;
(b) service charge to State Governments and the KVIC;
(c) turnkey construction fee;
(d) incentives to promoters;
(e) training programs;
(f) repair of plants with structural problems.

Total governmental expenditure in 1985/6 was Rs. 6,7 million (75% subsidies, 25% training) though less was budgeted for the following year.

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