BY Dr. K. C. Khandelwal
Advisor and Head, Rural Energy
Ministry of Non-conventional Energy Sources
Government of India, New Delhi – 110 003
The share of biomass resources, such as fuel wood, cattle dung and crop residues in the total energy consumption has declined significantly in the last five decades, but it is still more than 30 per cent. A point of concern is an increase in the quantity of consumption of biomass as a source of energy due to population pressure. Estimates indicate that about 300 million tonnes of fuel wood, 160 million tonnes of crop residues and 140 million tones of cattle dung are burnt every year for meeting energy requirements mainly for cooking and heating purposes. A large quantity of fuel wood is also consumed in commercial establishments, such as food processing, agro-processing, clay and metal-based industries, soap making industries, paper making industries, tobacco curing, etc., and also in the service sectors such as laundries, textile printing, etc. There is a lack of authentic data on fuel wood consumption, particularly in the industrial sector.
The present pattern is not sustainable because the estimated availability of fuel wood from recorded forests is placed in the range of 66 -123 million tonnes per year. This large gap between its supply and consumption is causing deforestation and desertification, thereby affecting agricultural production. The programme of social forestry and joint management of forests found successful in Orissa, Haryana and other States is needed in other States.
Women is the most disadvantaged population in our rural areas, facing the problem of drudgery due to daily collecting head-lot of fuel materials from long distances and burning them in traditional chulhas. Cooking with biomass causes severe indoor air pollution to which women, children below 5 years of age and senior citizens are especially susceptible. Estimates indicate 4.10 to 5.70 lakh premature deaths per year due to indoor air pollution in our country as reported recently by Indira Gandhi Institute of Development Research, Mumbai. Further, for each death, there are about 6 person-years of illness in the population. Therefore, greater efforts are needed urgently to promote indigenously developed improved chulhas and biogas plants on a massive scale.
The present paper describes the Indian biogas programme for meeting the energy demand in the rural areas.
Biogas technology involves natural processing of cattle dung for value added products,
mainly `biogas’, which is a clean and efficient fuel and ‘digested slurry’ which is enriched organic manure. Biogas can be used to replace diesel oil up to 75 per cent in a dual-fuel internal combustion engine. Making a provision for a gas-mixing device below the air filter modifies ordinary diesel engine. The consumption of biogas is about 0.45 to 0.50 cubic metre per H.P. per hour. Dual fuel engine can be used for running water pumps, chaff cutters, etc.
India has been a pioneering country in developing a simple-to-construct and easy-to-operate design of biogas plant in the year 1953. The model is internationally known as Indian design of floating gasholder type biogas plant, popularly called KVIC Model (Khadi and Village Industries Commission). In 90’s another model called ‘fixed dome’ was developed and is being promoted for household use. Design specifications are readily available for plant capacities suitable for individual households as well as institutions having cattle in the range of 3 to 200 heads. Details of quantity of cattle dung required for family type plants are given in Table 1.
Table1. Quantity of cattle dung needed for operating family type biogas plants.
No. of cattle Amount of Capacity of plant
cattle dung(kg./day) (cubic metres)
35 – 40 350 15
60 – 70 600 25
100 -110 1100 45
140 -160 1500 60
Ministry of Non-conventional Energy Sources (MNES) has been promoting household biogas plants under the Central Sector Scheme on National Project on Biogas Development since 1981-82. Large sized plants have been installed under the “ Community, Institutional and Night-soil based Biogas Plants Programme” from 1982-83 to 2002-03. The rates of central subsidy approved for the year 2002-03 are mentioned in Table 2.
Table 2. Rates of central subsidy approved for biogas plants for 2002-03.
I. Family type plants
Area/ Category Amount of central subsidy per plant
North Eastern Region States Rs. 11,700 /-
Jammu & Kashmir, Himachal Pradesh, Rs. 3,500 /-
Hilly areas and island States
Scheduled Castes and Scheduled Tribes, Rs. 2,300 /-
Desert districts, Small and marginal farmers,
Terrai region and Western Ghat
Others Rs. 1,800 /-
II. Institutional type plants
|Capacity of plant (cubic metres of gas production per day)
Amount of Central subsidy in Rupees for institutional plants
|Goshalas/ Pinjrapoles, charitable organisations/ Government institutions, co-operative societies, trusts and other institutions tied to such bodies
||Private and profit – making institutions and others
North Eastern Region States
Eastern Region States
So far over 32 lakh rural households have been benefited and are meeting cooking fuel and organic manure requirements through family type biogas plants. On an average about 1.7 lakh more such plants are installed every year. A total of about 3,500 large size biogas plants have also been installed. It includes plants in use at about 2500 cattle based organisations, such as goshalas, pinjrapoles, charitable trusts, private dairies, etc. Every year about 400 more such plants are installed.
RBI and NABARD have issued guidelines on financing of gobar gas plants to commercial and cooperative banks from time to time since 1976. Of late, however, the construction of biogas plants with bank loans has come to a negligible level. This lack of involvement of banks should be examined and remedial measures should be taken up on a priority basis.
Functionality of plants
Functionality of biogas plants and optimum capacity utilization is a point of concern. The diagnostic study conducted by Programme Evaluation Organization, Planning Commission in 19 States in the year 2001-02 indicated that only 81 per cent plants were commissioned and 66 per cent of the commissioned plants were found in use. Therefore there is still a need to make concerted efforts in improving the quality of construction of plants and providing maintenance servicing on call. The turnkey workers scheme, which envisages a provision of providing free maintenance servicing during the first three years was found to be effective in some States only. A direct relationship between the plant owners and the turnkey workers, instead of the involvement of State nodal agency or department is needed.
Programme for 2002-03
A target of setting up of 1.70 lakh family type biogas plants and 200 institutional biogas plants have been planned for the year 2002-03 with a budget provision of Rs.60.00 crore and Rs.3.50 crore, respectively. The programme is implemented by State Nodal Departments and Agencies, KVIC and regional level non-governmental organisations (NGOs), such Sustainable Development Agency, Kanjripally and Biotech, Thiruvananthapuram, Kerala. These agencies have staff for providing technical and training support in the construction and maintenance of biogas plants. Besides, Biogas Development and Training Centres (BDTC), which are functioning in eight States, are organising training for the staff of NGOs and State Governments, masons and technicians plant operators.
Special emphasis is laid on the promotion of the use of digested slurry as manure. The digested slurry improves physical, chemical and biological properties of soils. Extensive field trials conducted in various agro-climatic conditions, showed that yield of different crops was enhanced by 10 to 30 per cent when biogas manure was used @ 10-15 tonnes per hectare per year in irrigated lands and @ 5-6 tonnes per hectare per year in non-irrigated lands. Biogas manure can be used for coating of seeds to improve vigor of seedlings. Highlights of recent R&D achievements, which could be adopted for improving viability of plants, are summarized below:
(a) Studies have shown that the `digested slurry’ contains 80% carbon, 1.8% nitrogen, 1.0% phosphorus, 0.9% potash, 188 ppm manganese, 355 ppm iron, 144 ppm zinc and 28 ppm Copper. Therefore, the biogas manure is an excellent source of not only humus but also micronutrients for crops.
(b) Studies have shown that in general, about 50 to 75% of the recommended dose of inorganic N-fertilizer could be replaced by biogas manure without significantly affecting the grain yield of wheat, paddy, maize and sorghum crops. In fact, an increase in the yield of wheat, paddy, and maize crops has been recorded at many experimental sites conducted under the aegis of Indian Council of Agricultural Research (ICAR). Similarly 50% of the chemical N-fertiliser requirement of black gram, groundnut, and soybean crops could be met by using biogas manure. In case of chilly, potato and brinjal crops, the replacement could be 20-50% of N-fertiliser.
A scheme for organizing demonstrations on the use of digested slurry has been taken up during 2002-03 with objectives to collect scientific data and prepare and distribute publicity materials in local languages. Agricultural Universities and non-governmental organizations will conduct demonstrations. Each year a grant of Rs. 50,000 will be given for carrying out a demonstration in an area of about two hectares.
Attention has also been focused on generation of electricity in cattle based institutions, mainly gaushalas. An institutional biogas plant of 85 cubic metres capacity has been in operation since November 1997 at Idar Pinjrapole Gaushala, Gujarat, where biogas is used for generation of electricity in a 10 kVA diesel generator. The cost of generation of electricity from the plant is reported to be Rs.3.40 per unit (kWh). A joint programme with Animal Welfare Board of India (AWBI) was launched in 2000 –01 and is expected to cover about 150 institutions.
A new scheme of setting up cattle dung based power generation and marketing of manure has also been initiated during 2002-03. Financial support will be given at the rate of Rs. 1.00 lakh for preparing a detailed project report for projects of 100 to 250 kW and up to Rs. 2.00 lakh for projects of more than 250 kW capacities. For setting up power plant, Central financial assistance will be given at the rate of Rs. 30,000 per kW for a 100 to 250 kW project and Rs. 75,000 plus Rs. 25,000 per kW for a project of more than 250 kW. A detailed project report has already been prepared for setting up a power station at Sri Gopal Govardhan Gaushala, Pathmeda, Jalore, Rajasthan, which sustains cattle population of more than 15,000 heads. About 100 tonnes of cattle dung per day will be adequate for producing 5000 cubic metres of gas to generate 9100 kWh electricity.
The estimated cost of the project is Rs. 3.00 crore.
Tenth Five Year Plan
The Tenth Five Year Plan (2002-07) envisages a comprehensive Centrally Sponsored Scheme called “National Project on Biogas Development and Manure Management”. The plan target is to promote 10 lakh small biogas plants and establish at least 10 biogas power stations with a Plan Outlay of Rs. 350.00 crore.
Cattle dung is a resource. Our farmers are aware of its use as manure in agricultural fields but for want of alternate cheap cooking-fuel, they are left with no other option except to burn it in hearths. This age-old practice of burning dung cakes in the most inefficient manner should be dispensed with to conserve cattle dung for sustaining, rather improving soil health and in turn agricultural productivity. We are one of the leading countries in developing and promoting biogas technology. Still we have to travel a long way to make full use of this technology for developing our rural areas.
For better results, concerted efforts are needed in dovetailing the biogas programme with the Cattle Improvement Schemes on the one hand and with the Watershed Programme on the other. Good work done by trained masons, technicians, NGOs, etc., should be recognized by organizing healthy competitions at the block and district level and awarding the best performing persons and organisations. Plant owners, using biogas and manure efficiently should also be awarded on an annual basis. Do-it-yourself manual on the operation and maintenance of biogas plants for plant owners, construction manuals for masons, manuals on laying gas distribution pipe line and fixing burners and lamps and operation of duel-fuel engines for technicians, biogas plant users’ manual, etc. should be brought out in regional languages and widely distributed. The use of digested slurry in conjunction with chemical fertilizers should be encouraged to increase the fertilizer use efficiency. Further research data indicate that the use of biogas-slurry manure reduces the adverse affect of injudicious application of pesticides on soils. Therefore, to generate awareness among farmers, field demonstrations on the use of biogas-slurry manure should be organized. Also greater R&D efforts should be made to focus on diversified value added use of manure, e.g. for hardening of tissue cultured seedlings, abatement of soil-toxicity, as a source of micro-nutrients and root stimulant for fruit and vegetable crops, etc.
Several private dairies and gaushalas possess large number of cattle heads and many-a-time face the problem of disposal or use of cattle dung in towns and cities. To overcome this problem, the biogas technology coupled with electricity generation should be promoted with focus on production and marketing of manure.