Biogas Plant in India
Jo Lawbuary, HES
Contents
Introduction Why biogas?
Methanogenesis
Evolution of biogas technology
Dissemination of biogas technology
Factors hindering spread of biogas
Conclusion
References
Tables and Figures
Tables:
- Estimated potential of renewable technologies in India
- Different biogas plants recognised by MNES
- Daily dung requirements and dung fed
Fig1. Process of methanogenesis
Fig2a. common biogas plants a: KVIC floating-drum model
Fig2b. Camartec fixed-dome model
Frontispiece:
Biogas promotion poster produced by the Khadi and Village Industry Commission
Introduction
Mahatma Gandhi, in his vision for India, envisaged a system of devolved, self-sufficient communities, sustaining their needs from the local environment, and organising income generating ventures around co-operative structures. Fifty years on, and Gandhi's vision of Swadeshi (self-sufficiency) for India, despite interpreted by some as a romantic and bucolic notion, is perhaps more urgent than ever. Diminishing forests, and a burgeoning, mainly rural biomass-dependent population of 984 million, necessitates a co-ordinated effort of rural India to supply itself with a dependable and sustained source of energy.
Biomass alone currently meets 57% of the national energy demand, (Tata, 1998) yet is rarely featured in any 'official' statistics of energy use, given perhaps its scattered nature, and its low status as fuel. Indeed, according to statistics, in 1995, 63.3% of India's energy production was from its reserves of low-grade coal, 18.6% from petroleum, while hydroelectricity, natural gas and nuclear accounted for 8.9%, 8.2%, and 1% respectively (EIA, 1998).
India's overall energy production in 1995 was approximately 8.8 quadrillion Btu (quads), while consumption was 10.5 quads. India's energy demand is increasing, and its inability to step up production to meet demand, has increased India's reliance on costly imports, the gap between consumption and production projected to widen into the next century, as demand for energy is projected to grow at an annual rate of 4.6% - one of the highest in the world (EIA, 1998). Energy for developing industries, transport, and a drive towards the electrification of India over the last three decades of an expanding residential sector, so that currently, a great percentage of villages in the subcontinent have access to the grid- as much as 90%, according to recent figures (EIA, 1998), have contributed to the energy production deficit.
However, as mentioned earlier, the conventional statistics do not take into account the informal and unorganised use of biomass, which is reputed to account for 57% of total energy, therefore, effectively energy from biomass more than equals the marketable energy production of 8.8 quads (However, given the inherent difficulty in estimating such a figure, there must be a wide margin of error, potentially). Fuelwood is the primary source of biomass, derived from natural forests, plantations, woodlots and trees around the homestead (Agarwal, 1998). Alarm regarding the state of India's forests, which were being lost at an estimated rate of 1.5 million hectares (Mha) in the early 1980's has kick started an intense afforestation and forest regeneration scheme that attempts to share management of forest resources between the forest department and local user communities. Afforestation appears to be showing up on satellite images on the subcontinent (Hall and Ravindranath, 1994), but whether ultimately, more fuelwood will be available to rural communities, will be more a political question.
| Table 1: The estimated potential of various RES technologies in India (Tata 1998) | |
Source / System | Approximate Potential |
| Biogas plants (in millions)Improved woodstoves (in millions) Biogas (MW) Solar energy (MW / km2) Wind energy (MW) Small hydro power (MW) Ocean energy (MW) | 12 120 17,000 20 20,000 10,000 50,000 |
The government views biogas technology as a vehicle to reduce rural poverty, and as a tool in part of a wider drive for rural development. Alternative energy options are promoted by The Indian Renewable Energy Development Agency (IREDA), which operates under the Ministry of Non-Conventional Energy Sources (MNES). To promote and disseminate information about biogas technology specifically, the government has organised the National Project on Biogas Development nation-wide, and several NGO's have been active in implementing the programme on the ground. Active dissemination is also undertaken by the Khadi and Village Industries Commission (KVIC), in the context of rural development from small-scale income generating opportunities.
Currently, there are thought to be about 2.5 million household and community biogas plants installed around India (Dutta et al, 1997), though table 1 estimates that 12 million could be usefully employed. This essay will critically examine the drive to provide rural India with an 'appropriate' energy source, with particular reference to the rural poor. The potential benefits of biogas in a rural economy will be outlined, followed by the biological and biochemical foundations of methanogenesis, and the evolution of biogas technology. Case studies from different parts of India will be considered, from construction of biogas plants, to their long term functioning amongst the communities they are designed to serve.
Why biogas?
The enormous potential of biogas, estimated at 17,000 MW can be seen from table 1. The capacity was derived principally from estimated agricultural residues and dung from India's 300 million cattle. Biogas technology may have the potential to short-circuit the 'energy transition' Leach (1987) describes from biomass to 'modern' fuels. Biogas technology is a particularly useful system in the Indian rural economy, and can fulfil several end uses. The gas is useful as a fuel substitute for firewood, dung, agricultural residues, petrol, diesel, and electricity, depending on the nature of the task, and local supply conditions and constraints (Lichtman, 1983), thus supplying energy for cooking and lighting. Biogas systems also provide a residue organic waste, after anaerobic digestion, that has superior nutrient qualities over the usual organic fertilizer, cattle dung, as it is in the form of ammonia (Sasse et al, 1991). Anaerobic digesters also function as a waste disposal system, particularly for human waste, and can, therefore, prevent potential sources of environmental contamination and the spread of pathogens (Lichtman, 1983). Small-scale industries are also made possible, from the sale of surplus gas to the provision of power for a rural-based industry, therefore, biogas may also provide the user with income generating opportunities (KVIC, 1993). The gas can also be used to power engines, in a dual fuel mix with petrol (Jawurek et al, 1987) and diesel (KVIC, 1993), and can aid in pumped irrigation systems.
Apart from the direct benefits gleaned from biogas systems, there are other, perhaps less tangible benefits associated with this renewable technology. By providing an alternative source of fuel, biogas can replace the traditional biomass based fuels, notably wood. Introduced on a significant scale, biogas may reduce the dependence on wood from forests, and create a vacuum in the market, at least for firewood (whether this might reduce pressure on forests however, is contestable).
What is more certain, is the impact on rural womens' lives. Promoted by KVIC, and other bodies as 'eliminating drudgery of women' (see frontispiece), a regular supply of energy piped to the home reduces, if not removes, the daily task of fuelwood gathering, which can, in areas of scarcity, be the single most time consuming task of a woman's day - taking more than three hours in some areas (Lewanhak, 1989). Freeing up energy and time for a woman in such circumstances often allows for other activities, some of which may be income generating. Additional knock on benefits in this context, apart from a positive contribution to the household economy, may be an increase in personal status, both within the family, and the wider community, and a greater role in decision making; no small feat in the traditional gender power imbalance, characteristic of rural India. Alternatively, the saving, in terms of energy can perhaps contribute to a reduction in the gender difference in terms of food intake and proportion of energy expended in labour, which, according to Revelle (1976) is higher for a woman (over 15 years) at 44%, but lower in males at 38%. However, more likely is that a woman's energy will be directed in other areas.
A clean and particulate-free source of energy also reduces the likelihood of chronic diseases that are associated with the indoor combustion of biomass-based fuels, such as respiratory infections, ailments of the lungs; bronchitis, asthma, lung cancer, and increased severity of coronary artery disease (Banerjee, 1996). Benefits can also be scaled up, when the potential environmental impacts are also taken into account; significant reductions in emissions associated with the combustion of biofuels, such as sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), total suspended particles (TSP's), and poly-aromatic hydrocarbons (PAH's), are possible with the large-scale introduction of biogas technology.
The use of biogas systems in an agrarian community can increase agricultural productivity. All the agricultural residue, and dung generated within the community is available for anaerobic digestion, whereas previously, a portion would be combusted daily for fuel. Therefore more is returned to the land. Moreover, as mentioned earlier, the slurry that is returned after methanogenesis is superior in terms of its nutrient content; the process of methane production serves to narrow the carbon:nitrogen ratio (C:N), while a fraction of the organic nitrogen is mineralised to ammonium (NH4+), and nitrate (NO3-), the form which is immediately available to plants. According to Sasse et al (1991), the resulting slurry has double the short-term fertilizer effect of dung, while long term fertilizer effects are cut by half. However, in the tropics, the short term effects are the most critical, as even the slow degrading manure fraction is quickly degraded, due to rapid biological activity. An increase in land fertility, then, can result in an increase in agricultural production. The knock on benefits may include improved subsistence, increased local food security, or income generation from a higher output.
Biogas systems, then, offer an integrated system that lends itself to a rural setting; the plants can be maintained with a variety of organic residues, from humans, animals, crops and domestic food waste. Indeed, biogas plants could also be usefully employed in an urban environment also. Ranade et al (1987) successfully maintained a biogas plant of 25 litres capacity, fed with market waste, in Pune, western India and suggest such a system to be a viable option for solid waste disposal in areas of rapid urbanisation. Although this essay is more concerned with biogas in rural areas, the example does, nonetheless, demonstrate the potential of biogas technology and its multifunctional and flexible applications.
Integral to biogas technology also, and the philosophy it represents, namely Swadeshi, is the requirement of devolved, and self-reliant communities to manage the systems. This may seem a rather obvious point to make, but necessary nonetheless. For biogas systems to be truly viable and workable in rural India, demands the technology to be preferably generated from within the community. As will be seen later, this may not always be possible logistically, amongst other reasons. If not actually produced from the community it is to serve, then the technology must be amenable and possible to manage and modify by individuals within the community, preferably the plant owner, and reliance on 'outside' assistance kept to a minimum. Without this basic requirement being fulfilled, biogas technology will not be a truly viable option for meeting India's rural energy demands. With this in mind, the government agencies involved in designing biogas plants have attempted to create plants that could be maintained locally. Although the designs have evolved over the last forty years since their inception which will be outlined later, the microbial processes around which they are built, methanogenesis, remains the same.
Methanogenesis
Methanogenesis is a microbial process, involving many complex, and differently interacting species, but most notably, the methane-producing bacteria. The biogas process is shown below in figure 1, and consists of three stages; hydrolysis, acidification and methane formation.
Figure 1: The process of methanogenesis (After GTZ, 1999).
In the first stage of enzymatic hydrolysis, the extracellular enzymes of microbes, such as cellulase, protease, amylase and lipase externally enzymolize organic material. Bacteria decompose the complex carbohydrates, lipids and proteins in cellulosic biomass into more simple compounds. During the second stage, acid-producing bacteria convert the simplified compounds into acetic acid (CH3COOH), hydrogen (H2), and carbon dioxide (CO2). In the process of acidification, the facultatively anaerobic bacteria utilise oxygen and carbon, thereby creating the necessary anaerobic conditions necessary for methanogenesis. In the final stage, the obligatory anaerobes that are involved in methane formation decompose compounds with a low molecular weight, (CH3COOH, H2, CO2), to form methane (CH4) and CO2 (Gate, 1999). The resulting biogas, sometimes referred to as 'gobar' gas, consists of methane and carbon dioxide, and perhaps some traces of other gases, notably hydrogen sulphide (H2S). Its exact composition will vary, according to the substrate used in the methanogenesis process, but as an approximate guide, when cattle dung is a major constituent of fermentation, the resulting gas will be between 55-66% CH4, 40-45% CO2, plus a negligible amount of H2S and H2 (KVIC, 1993). Biogas has the advantage of a potential thermal efficiency, given proper equipment and aeration, of 60%, compared to wood and dung that have a very low thermal efficiency of 17% and 11% respectively (KVIC, 1993).
Methanogenesis or more particularly, the bacteria involved in the fermentation process are sensitive to a range of variables that ultimately determine gas production, and it is worth briefly outlining these factors. Temperature is perhaps the most critical consideration. Gasification is found to be maximised at about 35oC, and below this temperature, the digestion process is slowed, until little gas is produced at 15oC and under. Therefore in areas of temperature changes, such as mountainous regions, or winter conditions that may be more accentuated inland, mitigating factors need to be taken into account, such as increased insulation (Kalia, 1988), or the addition of solar heaters to maintain temperatures (Lichtman, 1983).
Loading rate and retention period of material are also important considerations. In the KVIC model, retention ranges between 30-55 days, depending upon climatic conditions, and will decrease if loaded with more than its rated capacity (which may result in imperfectly digested slurry). KVIC state that maximum gas production occurs during the first four weeks, before tapering off, therefore a plant should be designed for a retention that exploits this feature. Retention period is found to reduce if temperatures are raised, or more nutrients are added to the digester. Human excreta, due to its high nutrient content, needs no more than 30 days retention in biogas plants (KVIC, 1983).
Other factors likely to affect methanogenesis are pH; gas production is found to decrease with increasing acidity, and can result from over-loading the plant, which may stimulate the more fecund acidophiles, at the expense of the more tardy methane-producing microbes. Improved nutrient content, also, as mentioned above will increase the digestion process, and can be manipulated by the addition of animal (and male human) urine, while toxic substances, such as heavy metals may inhibit gas production (KVIC, 1983).
Understanding the process of methanogenesis allows manipulation, which can serve to maximise gas production in the field. Workers over the last twenty years have experimented with the digestion process, and have made strides in increasing gas yields, using techniques that can be similarly employed in a rural environment. Sharma et al (1988), have shown that biogas generation is increased when the particle size of organic material is small, in this case, less than 1mm. The workers recommend that a physical pre-treatment, such as grinding would improve a system's performance, and could also reduce the size of digester needed. A manual machine for physical pre-treatment of material would be a viable piece of equipment in a rural environment; indeed, there may be a similar piece of equipment already in use.
Other workers have found that biogas production is accelerated by the presence of metal ions in biomass (Geeta et al, 1990). The species principally researched was water hyacinth (Eichornia crassipes Solms.), which flourishes in eutrophic water bodies. The plant characteristically grows at high densities, which often leads to clogging, and is therefore considered an environmental pest. Water hyacinth, however, also concentrates nickel from eutrophic environments, upto 0.27 kg h/day, which, when mixed with bovine excreta upto 25 parts per million (ppm) was found to enhance gas production by 40%. The use of E. crassipes in biogas systems can both increase gas production, and contribute to environmental management, by way of controlling a pest.
Research in other areas has focused on the composition on the substrate, and its effect on gas production. Habig (1985), fermented a range of organic materials from marine macroalgae to vegetables and discerned that carbohydrate and protein are the principal components utilised during methanogenesis.
Such work is invaluable in enabling a sound management and manipulation of methanogenesis, and can be of use to users in a rural environment.
The evolution of biogas technology
Biogas plants in India were experimentally introduced in the 1930's, and research was principally focused around the Sewage Purification Station at Dadar in Bombay, undertaken by S.V. Desai and N.V. Joshi of the Soil Chemistry Division, Indian Agriculture Research Institute, New Delhi. The early plants developed were very expensive and were not cost effective in terms of the gas output, indeed the early models were not producing enough gas to supply a small family (KVIC, 1993). Some of the early models were also prone to burst, so overall, the technology was not viable for dissemination.
Over the next twenty years, Jashbhai Patel designed and made several small-scale biogas digesters, envisaging farm labourers as the user. Although other individuals and institutions were also designing biogas plants, in 1961 the Khadi and Village Industry Commission chose to promote Patel's design, which, although more costly than other models, was more productive, had a longer life, and required minimal maintenance (KVIC, 1993).
The basic plant, which came to be known as the KVIC model, consists of a deep well, and a floating drum, usually made of mild steel. The system collects the gas, which is kept at a relatively constant pressure. As more gas is produced, the drum gas holder consequently rises. As the gas is consumed, the drum then falls. The biomass slurry moves through the system, as the inlet is higher than the outlet tank, creating hydrostatic pressure. Only completely digested material can flow up a partition wall, which prevents fresh material from 'short-circuiting' the system, before flowing into the outlet tank. Dimensions of the plants depend upon the energy requirements of the user (Lichtman, 1983). The basic system can be seen in figure 2a. By the early1980's, there were thought to be about 80,000 systems built by KVIC.
Figure 2a: The KVIC floating drum model (Lichtman, 1983)
Figure 2b: The Camartec fixed dome model (Sasse et al, 1991)
Research into anaerobic digesters continued around the country, and the Planning Research and Action Division (PRAD) based in Uttar Pradesh, northern India developed the 'Janata' fixed-dome plant, based on a modified design widely used in China. Key features of the Janata model, is the fixed-dome, in contrast to the floating dome of the KVIC model. With this design, the inlet and outlet tank volumes are calculated for minimum and maximum gas pressures based on the volumes displaced by the variation of gas and slurry within the system (See figure 2b). The Janata system is about 30% cheaper to construct than a KVIC model of the same capacity with added advantages that there are no moving parts, making local construction possible and maintenance easy. Lichtman (1983) notes that savings may diminish with scale with this design, so Janata may be more appropriate for small-scale users. One disadvantage with the fixed-dome design is that gradual accumulation of sludge is likely within the system, making periodic cleaning necessary. In china, where similar designs are widely used, small birds in cages are placed inside the digesters prior to human attempts at entry. In a variation of the canary and mining scenario, if the canary lives, it is assumed that there is no concentrated CH4, which is highly toxic and potentially explosive, and hence safe for humans (Lichtman, 1983).
Anaerobic digester design has continued to evolve over the years, but systems are generally variations around the theme of the floating-dome and the fixed-dome design. Often construction materials vary, or loading positions differ. Table 2, below, shows some of the most common biogas plants that are recognised by the government.
| Table 2: Different types of biogas plant recognised by MNES (Ministry of Non-Conventional Energy Sources). After Gate, 1999. |
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Dissemination of biogas systems:
Since the 1960's, biogas systems have been implemented in India, but it was in 1981 with the beginning of the sixth 5-year Plan, and the formation of the National Project for Biogas Development (NPBD), when the drive to step up dissemination was taken, perhaps also reflecting the alarm of fuelwood shortages at the time.
Currently, there are thought to be about 2.5 million biogas plants installed around the country (Dutta et al, 1997), though the potential of large-scale implementation of biogas technology remains unrealised. According to MNES, in 1991, the use of electricity for cooking, which includes biogas, only accounted for about 2% and 3% for rural and urban areas respectively, and sharply demonstrates the continued minority status of this alternative fuel.
The Tata Research Institute, New Delhi, estimates that 12 million biogas systems in total could be installed over the subcontinent, while GATE, an alternative energy NGO based in Germany, estimates the total potential number of plants that could usefully be employed to be 30 million household-size, and nearly 600,000 community-size plants, one for each village. However, it is not clear on what data these estimates are based on.
Nonetheless, there is still enormous potential for biogas technology, and the government continues in its drive for more widespread implementation. However, for biogas to be considered as a viable source of fuel, depends not only on an effective dissemination programme, and extension, but also upon the success of existing plants in the field. Although literature could not be found regarding the success rate of the 2.5 million biogas plants installed to date, e.g., how many are fully operational, which may be indicative of a lack of consequent monitoring, it would be instructive to examine the implementation of biogas systems in rural India, to determine how the technology has been received on the ground.
Implementation of biogas technology is overseen centrally by MNES, but actual dissemination is devolved to the individual state governments, public corporations, such as KVIC, the National Dairy Development Board (NDDB), and also NGO's. Although there will be differences between states, the general approach to disseminate biogas technology is based on a system of subsidies and concessions, to encourage uptake.
Subsidies are granted on plants upto 10m3 (a large family-sized system), and usually for the models recognised by the government, as listed in table 2, though there may be regional differences. Allowances are paid towards investment costs, to every user and for every biogas plant that is installed, in what may be interpreted as a measure of intent to promote biogas technology, and perhaps the most critical instrument in determining initial uptake. The extent of the allowance is dependent on the size of plant, socio-economic status of the user, and geographical region, according to rules worked out by central government. India has been divided into three areas according to altitude; the mountainous north-east is where the highest allowances are paid, perhaps reflecting the commonly held notion that tribal communities are depleting forests (Maikhuri and Gangwar, 1991). Mountainous, or high altitude areas in other states form the second category, and the remaining states make up the last category. Here, socio-economic status largely determines the size of the allowance, with priorities for scheduled caste and tribe, and smallholders. Landless and marginal farmers are entitled to higher allowances than farmers not in the fore-mentioned groups who have more than five hectares (GATE, 1999). Other allowances exist for bodies to establish and maintain an organisational infrastructure, subject to reaching certain targets, of which a percentage must be allocated in the provision of follow up services and monitoring.
Subsidies certainly appear to have encouraged up take, and participation seems to be high amongst target groups, such as marginal and smallholders. This can be demonstrated in the size and type of digester opted for. Orissa, on the east coast, is one of the poorest states in India, and characterised by smallholders of approximately 1.6 ha, less than the average of other states, and agriculture is the principal industry in Orissa. Therefore, it is not surprising that of all the digesters, the most popular is the smallest capacity fixed-dome Deenbandhu model, at 6m3, which accounts for 84% of all plants installed (Gram Vikas, 1991). Similarly, in Sangli, Maharashtra western India, where there are 345,000 biogas digesters, more than any other state, the same Deenbandhu model accounts for 85% of all systems constructed (GATE, 1999).
However, Chand and Murthy (1988) note that up take is no guarantee of a successfully operating plant. From studying installed systems in Maharashtra, western India, the workers note a correlation between decreasing land size and non-functioning plants. Similarly, Moulik (1981) maintains that of the early biogas plants installed a great percentage, perhaps as many as 70%, are inoperative. Moulik explains that in the enthusiasm to promote biogas technology, many 'marginal' farmers and landless were hastily provided with plants, as full subsidies were given, and NGO's and other organisations had targets to reach. However, many were to remain inoperative, due to a variety of reasons, but critically, due to an inability to fulfil the requirements necessary for operating the plant.
Moulik states that however well intentioned, the biogas programme cannot cater to the needs of the poorest and marginalised, as these groups fail the technical requirements to maintain a viable plant. More specifically, for even the smallest-sized plant, three to four cattle are needed to provide the necessary quantity of dung. Less than this, and the plant is not economically or operationally viable.
Moreover, considerable constraints may also exist in the provision of space and water that are likewise necessary for a biogas plant. According to Moulik, the smallest 3m3 family size plant requires about 27m2 of land, when area for the plant and a compost pit for the slurry is taken into account, which in many circumstances may not be available. The characteristic clustering of houses in a village between networks of narrow lanes may render land enough around the homestead to accommodate a biogas plant as the exception, rather than the rule. Even if surplus land is available, issues of land tenure and ownership may prohibit the construction of a plant.
Water scarcity, or difficulty in obtaining water, e.g., from a distant source, may also impose further constraints on the viability of biogas technology in a rural environment. To function properly, a biogas plant requires feeding a mixture of cow-dung and water, in the ratio of 1:1 or 4:5, thus imposing a significantly higher daily water demand over domestic needs. If there is difficulty in obtaining water, particularly resonant for low caste groups in a village environment, who may not have the same resource access rights as others, or general scarcity, then the maintenance of a biogas plant may not be possible.
Given the above, Moulik estimates that perhaps only 10-15% of the rural population fulfils the technical requirements. Despite a well-intentioned attempt to cater for the energy needs of rural India, and particularly the poor, as defined by 'scheduled caste' and 'scheduled tribe', the biogas programme seemingly cannot meet these needs, through insurmountable constraints associated with their very marginality, ironically. In this sense, then, the biogas programme may be an unrealisable notion, and the Gandhian aspirations of Swadeshi, little more than a bucolic dream. However, it may be instructive to briefly consider a case study, to understand how biogas technology has been received in targeted areas.
In the 1980's, the NPBD was active in promoting biogas in low-caste and tribal areas of Udaipur, Rajasthan, north-western India. Nag et al (1986), conducted a survey in eight villages of mixed caste and tribe, in an attempt to assess the impact and effectiveness of NPBD in these areas. 114 samples of families who had installed biogas plants under the NPBD programme upto 1985, notably the cheaper fixed-dome Janata were considered. The data revealed some interesting findings; of the 114 beneficiaries, 107 were registered as 'landless' or 'marginal', though the survey discovered the plant owners were mostly the wives or sons, of landowners who owned between 6-20 acres of land. These family members had been encouraged to apply to make use of the higher rate of subsidies available for marginal and landless groups. Only 10 were found to be scheduled caste or tribe with poor landholdings.
Curiously, Nag et al interpret the results as a success for the NPBD, and describe the scheme as a 'peoples' programme'. That participation amongst farmers is high is a positive sign of the potential role of biogas in an agricultural community, however, the programme does not appear to be delivering to the rural poor, as defined by scheduled caste and tribe, which may be indicative of the inherent incompatibility of the technology with regard to marginalised groups. Nag et al, note a correlation between education level, and uptake, attributed to a greater exposure to biogas promotion through the media, etc.. Of the 10 scheduled caste and tribe beneficiaries, 8 were illiterate, and according to Nag et al, 'adopted biogas plants only when told by their masters'. However, the lack of a formal education in such groups is perhaps more indicative of their general marginality; economically and socially.
Uptake of biogas technology among scheduled caste and adivasi (tribal) groups, then is found to vary across the subcontinent, though even where participation is high, the technology may not be truly viable. Biogas, however, does appear to be taken up more successfully by the more wealthy sectors of the agricultural community. As Nag et al (1986) note, over 30% of the families with biogas plants sampled were found to be engaged in more than one service or business, which is usually an indication of entrepreneurship and solvency. Further, according to Nesmith, (1991), biogas technology appears to be associated with status and wealth, and was observed most commonly in top income groups in a study in West Bengal, eastern India. (This association with wealth may well be a hindrance to the wider dissemination of biogas technology amongst groups who may view themselves as perhaps not fully entitled to it).
As household size plants may be generally non-viable to many scheduled caste and adivasi groups, community size plants might be more appropriate. Larger sized plants, servicing a cluster of houses, or indeed a whole village, may overcome the seemingly insurmountable problems apparent regarding individual plants and the rural poor, as discussed earlier. However, Lichtman (1983), states that the government subsidy system has discriminated against the provision of community-size plants, by subsidising upto 6m3 plants only (and later upto 10 m3). Thus, wealthier farmers have been able to apply for grants and loans to construct household size systems, while larger plants that may benefit the wider community, have been ineligible for support. In this way, the government subsidy programme may be interpreted as discriminating against the poorer sections of the community, while supporting the wealthier farmers.
However, where community plants have been constructed, many problems have been encountered. Singh (1988) randomly sampled half the beneficiaries of seven community biogas plants in Punjab, northern India, after the first year of operation, and discovered considerable technical, economic and social problems. Singh found that all the plants were being routinely underfed with dung, by 30-50%, as shown in table 3. In one case, the entire daily dung load needed bringing from the nearest city. Although, in theory, there was enough cattle to provide the required amounts of dung, competing demands with non-beneficiaries were evident, who collected dung for fuel, in the absence of crop residues. Gas production was also found to fall to 30% of its rated production in winter months, due to greater direct use of dung, for fuel.
At the time of writing the paper, Singh noted two plants to be non-operational, principally due to problems associated with the availability of labour. Labour shortages were attributed to economic factors, such as low pay compared to agricultural labour. Social factors were also evident in the non-availability of labour, particularly the stigma associated with working with dung; considered as a low-caste task, and usually performed by women. However, in this instance, the volume of dung involved in the daily maintenance of the community plants, 3000 kg, was considered beyond the physical strength of women labourers, given its dispersed nature and
Table 3: Daily dung requirements and dung fed (quintal =100kg) (Singh, 1986)
| Name of village | Dung requirement | Dung fed | Difference | ||
| From village | From outside | Total | |||
| MehdoodanPeharkalan Ablowal Passiana Hambran Pandori Chabewal | 3030 30 30 95 30 30 | 1416 10 12 45 12 - | -4 10 10 - 3 30 | 1420 20 22 45 15 30 | 1610 10 8 50 15 - |
Singh describes the experience of scheduled castes and tribes; the targeted beneficiaries of the community biogas system. It was found that dung was having to be purchased in substantial quantities to feed some of the plants, upto 1000kg in several, while in one, the entire 3000kg daily need was having to be imported (See table 3). While dung purchasing costs were high, and increasing, returns on the sale of slurry were considerably smaller than estimated, between 15-30% of the expected revenue. Consequently, an increase in the gas charges was necessary to cover costs, and prices were raised from Rs30 to Rs50 per month. The increased prices could not be borne by many of the scheduled caste and adivasi community, and many disconnected themselves from the supply. In one village, Mehdoodan, 24 of the 29 scheduled caste and tribe connections to the biogas supply were duly removed.
Community biogas plants, then, appear to be logistically difficult to co-ordinate, and, certainly in the Punjab, similarly failing the sections of the community most in need of a reliable source of energy. Other workers have reported community biogas plants failing for reasons such as political feuds (Lichtman, 1983), and due to variable climatic conditions, that resulted in the forced sale of cattle (Lichtman, 1983). However, there have also been reports of community biogas plants successfully maintained by collective management efforts. Hall et al, (1992) report the eventual success of a community biogas system in Pura, southern India, after several years of problems, and a change in the end use of gas. The programme was implemented with the help of The Centre for Application of Science and Technology to Rural Areas (ASTRA), which considered Pura, a village of 430, with 240 cattle, suitable for a community biogas plant. ASTRA calculated that manure from the village could fuel a biogas plant sufficient to provide for all cooking needs, and generate surplus gas for lighting and pumping drinking water. The plant became operative in 1982, but serious logistical problems became apparent, as gas would run out before the cooking of the second daily meal. Conflicts ensued between villagers regarding contributions and share of benefits, and the project stopped in 1984. Interestingly, when ASTRA attempted to revive the project, and suggest that the gas could be used solely for generating electricity for lighting, it was discovered to ASTRA's surprise, that the villagers' top priority was actually the provision of safe drinking water. ASTRA duly acted according to the village needs, rather than work to their own assumptions, and by all accounts, the programme is now a success. The standard of living has been raised, and management is possible by the tangible benefits enjoyed by the whole village. At the time of writing the paper, Hall et al report that the success of the programme has encouraged residents to consider building a wood gasifier, to bolster their energy supply.
Factors hindering spread of biogas
It would be worth briefly considering the problems associated with the alternative technology, in terms of technical/operational, economic, and cultural aspects, which may potentially hinder its spread. Finally, the government's overall approach in disseminating biogas technology will be considered.
Technically, problems have arisen from installing too large a capacity plant, either by accident or design. Nag et al (1986) discovered that there was a general tendency for householders to construct an over-sized plant, even when they were only used for cooking purposes and not applied to wider energy demands. Too large a plant was found to lead to under feeding, and eventual failure of the plants to produce gas. Under feeding was also found to occur due to the under-collection of dung, estimated typically at 30-40% of the required capacity, and principally due to cattle being worked in the field, which would also lead to a reduction in gas production. Dung may also vary in its availability. As mentioned earlier, in areas of climatic instability, the occurrence of drought may reduce dung availability, by forced sale of cattle, or even death of cattle. In some areas, the plant may not be technically feasible all year round due to low winter temperatures that inhibit methanogenesis (Singh 1985, Sudhakar and Gusain, 1991).
Sometimes the plants are faulty in their construction, or develop problems that lead to the non-functioning of the plant, due to shoddy construction (more relevant to the fixed-dome models, than the floating dome, which comes pre-cast). Chand and Murthy (1988), analysed factors in the non-functioning of plants in Maharashtra, western India. The workers discovered that often, specially trained masons in biogas plant construction were overlooked, due to their higher cost, in favour of cheaper trainees, or those with no training at all, and often encouraged local by the government agencies, to meet ambitious targets. Chand and Murthy identified 50% of 1670 plants in the study as incapable of ever being made functional.
Economically, biogas systems have been shown to be cost-effective (Nag et al, 1985). Lichtman (1983) modelled different energy use scenarios of village size plants in Pura. The analysis was site specific, and localised in its approach. Lichtman found that in 78% of the situations modelled, the village showed a net gain. This percentage is likely to decrease in the consideration of smaller, household size systems (Sodhiya and Jain, 1988). Lichtman concedes, however, that it is more profitable to maintain a community-size system as a public utility and fertilizer plant, than as a source of cooking gas, subject to the viable provision of an alternative energy source for cooking, such as woodlots (Verma and Misra, 1987), and for fodder. Biogas production could perhaps be linked to small-scale industries.
Despite the positive cost-benefit of biogas technology, the 'macro-environment', may discriminate against the uptake of biogas. Bhatia (1990) notes that the macro-environment which determines price structures of conventional fuels most likely acts as a disincentive to adopt renewable technologies, generally. Subsidised conventional fuels, such as electricity, along with free connection to the grid for farmers, will continue to make non-renewable technology the cheapest option, unless subsidies for biogas can be brought into line, or prices of conventional fuels raised.
The system of grants and loans may hinder the correct choice of plant for different users, such as the ineligibility of community size systems, due to their size. While finally, another point in prohibiting uptake may be the perceived unnecessary switch from the existing free source of energy, such as wood and crop residues (Moulik, 1983).
Cultural practices may also hinder general uptake, due to reluctance to adopt different behaviour, particularly regarding the use of latrines in biogas systems (Singh, 1988). Traditional cooking practises may also need to be altered. Moulik (1983) reports that a common complaint about the use of gas burners for cooking, is that the staple bread chapati, cannot be properly roasted, also the cooking of dal (pulses) may be increased. Further, women are not necessarily the decision makers in a household, and the men of the household may not consider benefits, which mainly accrue to women, to be of significant urgency (Moulik, 1983).
Some of the problems discussed above may be overcome, through effective selection processes for the technology, and proper extension and support services. By all accounts, the government does not seem to be effectively organised to achieve such a goal, and a high number of non-operative biogas plants are likely to continue. Criticisms of NPBD have been widely articulated, from the lax selection process, to the arbitrary fixing of regional targets, which are then pursued. Chand and Murthy (1988) discovered in study of biogas uptake in Maharashtra, that in a sample of 1670 plants, 1086 beneficiaries were found not to qualify under the feasibility criteria. Further, when complications have arisen in the functioning of plants, a common complaint articulated is that there is a lack of available technical support (Sudhakar and Gusain, 1991). In this way, plants may be allowed to fall into disrepair, when their functioning may depend upon adequate maintenance skills, which should be available in every village. There is a danger that biogas may come to be thought of as a useless and inappropriate initiative, a folly imposed from policy makers and NGO's.
Compared to the biogas programme in China, where seven million household and community biogas systems have been successfully installed, India has a long way to go to realise the benefits of biogas technology. China, through the creation of effective institutions and by placing an emphasis on training and education, has achieved widespread dissemination of biogas technology (Ruchen, 1981, Daxiong et al, 1990), though the social organisation may particularly facilitate the spread of new, community-focused technologies.
Workers stress the need for micro-planning (Lichtman, 1983), so that genuinely appropriate biogas technology is made available to rural communities. Moulik (1983) emphasises the importance in promoting the participation of local people in the whole process of education, planning and monitoring, so that the renewable technology is viable and sustainable in the communities it is designed to serve. Other workers also propose co-ordinated management information systems as part of biogas development, in order for problems to be identified and remedial measures undertaken (Chand and Natarajan, 1987, Chand and Murthy, 1988).
Conclusion
Biogas has shown to be a useful component in the rural economy in India, though its application is logistically difficult. Ill-co-ordinated dissemination has led to high rates of non-functioning plants, and may endanger further uptake, as such, its status as a fuel remains marginal.
Participation in biogas technology varies across socio-economic groups, and across regions. Despite a well-intentioned attempt to cater for the energy needs of rural India, and particularly the poor, as defined by 'scheduled caste' and 'scheduled tribe', the biogas programme has not appeared to meet these needs on any meaningful scale, through insurmountable constraints associated with their very marginality, paradoxically. Limited success has occurred in other agricultural groups.
Further, the essential 'commodification' of dung, which has occurred since the introduction of biogas systems may impact detrimentally upon the poorest families, who may experience a scarcity of the fuel once gathered for free. The need to provide rural India with a viable and sustainable source of fuel has perhaps never been more urgent, yet curiously, this is not reflected in current literature, as biogas seemingly drops out of journals in the 1990's, as a subject to be written about. Therefore, the very current situation regarding the status of biogas technology in India is unknown, though dissemination is still being undertaken. Bapu's (Gandhi's) dream therefore remains largely unrealised, though 'small steps' may have been achieved.
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