Sustainability and Rural Livelihood Security Based on Biomass Gasification: An Assessment

Abstract

The applications of gasification products comprise impending use as process output that can be converted into mechanical, electrical and/or heat energy use in several industries and sectors including rural households. Different types of agricultural and forestry residues, energy crops, dairy-house, piggery, poultry, domestic and industrial wastes can be used as feedstock. With or without pre-treatment, the feedstock biomass can be gasified under different technological conditions viz. in a biochemical digester (biogas plant) or in a thermal digester (gasifiers), to find out what are the most suitable conditions for maximum energy outputs. Rural livelihood safety by the use of biogas plants was also assessed. The savings in fuel, overall family income, living cost, a slurry of biogas plants used as manure, and reduction of greenhouse gases at the domestic level were also studied. Overall annual family income varied from Indian Rupee (INR) 2,50,000–27,50,000. Annual livelihood cost was averaged at INR 1,66,714 and 1,83,529, respectively, with and without the usage of biogas plants. Biogas plant usage helped families save INR 10,295 (with savings of 1389 kg of fuel wood and nine cooking gas cylinders). Biogas plant usage also prevented methane (755 kg) and ammonia (267 kg) gas emissions annually.

1. Introduction

Sustaining livelihood in today’s world regarding quality of life, better living, economy, growth, employment and production needs energy. Shortage in the supply of energy, by any means, could disturb the national economic process and livelihood of people. India is deficient in energy. It has already been indicated that nature’s energy reserves are depleting, and in the coming days, it will become difficult for us to maintain energy availability [1]. Agricultural and forestry residues, energy crops, dairy-house, piggery, poultry, domestic and industrial waste-based biomass as renewable resources will play a key part in substituting conventional fuels. About 83% of parts will be of biomass from all renewable energy generation resources [2]. Agricultural biomass is readily available and can be used to drive energy continuously. Future regional as well as rural energy needs would have to be based mainly on renewable resources, whereas implementing and integrating systems of regional energy sustainability for bigger cities, industries, towns, villages, smaller settings, etc., remains a problem even now [3]. Renewable energy sources, technologies and user applications are becoming more relevant and also call upon society to maximize and universalize their use as early as possible [4].

Farmers having abundance of agricultural wastes, a local source of energy, can become energy source supplier instead of producers of raw material. For the supply of electricity and heat at farms, biochemical conversion (anaerobic digestion) of livestock excreta would be a suitable method. Spent-digested wastes used as fertilizer virtually resulted in wider reutilizing of nutrients [2]. Gas formation through bacteria in anaerobic digestion depends upon number of environmental factors, with temperature variation being the important parameter. Bacterial activity for anaerobic digestion works best in the temperature range of 20–55°C. Anaerobic gasification of biomass at higher temperatures, within the given range, ensues swiftly. Gas production doubles at an increment of about each 5°C of temperature, below 20°C, it decreases severely and nearly halts at 10°C [5]. Therefore, during colder times when gas production from biochemical conversion (anaerobic) process retards it would be wiser to shift to the thermo-chemical conversion of biomass to balance the energy demands for sustaining rural livelihood.

Thermo-chemical conversion for gasification of biomass is the most promising route for biomass utilization [6] and is regarded as a sustainable energy technology used for waste management and producing renewable fuel [1]. Capturing atmospheric CO₂ and sulfur became a topic of interest in compatibility with conversion of biomass, environment benefits and is inexpensive over a wider capacities. Through thermal route, biomass can be converted to gaseous fuel in limited atmospheric conditions [6].

Depending upon location and owner’s choice, transformation of variety of waste into usable ones may convert waste into a resource. Animal farm wastes converted into biogas make it an environment friendly reusable form of energy source [7, 8]. In agro-based country like India, vast quantities of wastes comprising cattle dung are produced endlessly. Biogas plants could convert, economically, the wastes into energy that advantageously helps in solving regional as well as rural power crisis. Biogas plants have a bright future in city corporations, metro and rural areas, producing tonnes of biological wastes, which otherwise go to waste and pollute the environment. Wastes can be utilized appropriately for power production and saving the environment from pollution [9]. Punjab state of India houses thousands of working family-size biogas plants with 5–10 cattle heads. About 4000 dairy farms with cattle head capacity ranging from 50 to 500 produce milk every day. Also, a large number of stray cattle are being housed in public cattle yards (‘Goushalas’). A large quantity of biogas can be produced using large capacity (50–500 m³ per day) biogas plants from the huge availability of cattle dung [10].

Under anaerobic conditions, biodegradable material is acted upon by methanogenic bacteria to produce biogas [11, 12]. Biogas contains 50–70% methane (CH₄), 30–40% carbon dioxide (CO₂), apart from other gases like hydrogen (H₂), ammonia (NH₃), hydrogen sulphide (H₂S), nitrogen (N₂) and water vapors (H₂O). Methane and hydrogen in biogas are energy sources that can be easily converted into heat energy (for cooking and lighting) and mechanical energy via internal combustion/gas engines. Additionally, biogas spent slurry can be used as organic fertilizer in agricultural farms to cut down usage and dependency on chemical fertilizers. In this way, biogas plants helps replace conventional energy sources, reducing emissions of harmful gases and mitigating the bad effects of carbon released to environment [13]. Produced biogas can be used locally or may transported over a longer distance by upgrading to natural gas equivalent quality [8].

Biogas plant economy depends on noteworthy investment costs, operation and maintenance costs, raw materials (available freely, most of the time), like cattle/animal dung, poultry droppings, organic wastes of household and industries, sewage sludge, aquatic and terrestrial plants etc., costs and income gained from the sale of gas and dried slurry. Supplementary value additions may be enriched biofertilizer production, greenhouse gas emission reduction and decreased cooking time and fuelwood collection. The system economy is also site-specific as prevalent market rates affect the cost of input/output, farming practices followed and management practices adopted by the involved community, etc. [14]. Certain factors, such as the incorporation of advanced technologies of feedstock processing, energy conversion and knowledge of complexities between plant size and costs involved, affect the impending biogas energy cost [15].

It has been well illustrated that biogas production and use have the capabilities to reduce the fuelwood usage and deforestation, cessation of indoor air pollution, thereby improving women’s and children’s health, reduction of greenhouse gases to mitigate global warming, availability of organic fertilizer for improving soil health, generating income, better sanitary conditions, reducing dependence on imported fuels etc. [16, 17]. The availability of enhanced livelihood facilities to users has been highlighted despite the fact that the user’s awareness and appreciation were partial. The need for householders training, in particular educating the women, was proposed for adequateness of feedstock, system upkeep, environmental benefits and possible livelihood security [18].

Rural livelihood hangs on agriculture for sustainability. Without access to electricity, firewood has been used as the basic cooking fuel. The present condition has an adverse effect on the environment and is unsustainable. The biogasification addresses the said apprehensions as being the simple yet powerful option for providing better fuel for cooking and lightning, empowering households by saving time with lesser environmental concerns like dispensation of animal wastes, contamination of groundwater, greenhouse gas emission and threat of climate change [19]. Households, using biogas from 18 to 24 months were 41.4%, having large size (>20 m³) biogas plants were 69.4%, have incurred 50–60 thousand Pak Rupee (PKR) as making cost were 41.7%, out of a survey sample. Monthly savings of 3–3.5 thousand PKR by 30.6% and more than 3.5 thousand PKR by 20.8% were made by households using biogas in comparison to conventional fuel costs [20].

Focus on the use of biogas as a renewable energy technique to realize socioeconomic and environmental sustainability was made that combines the production, consumption and natural/industrial ecosystems research. A framework was developed for adopting biogas energy in industrial and rural ecosystems as bottom-of-the-pyramid. It was suggested to embed a meta-dimension into the dimensions of biogas industrial ecosystem to enable socioeconomic and environmental sustainability [8]. In developing countries and humanitarian camps, organic waste management addresses hygiene and sanitation, which otherwise causes serious health issues that may lead to premature deaths [21]. Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PBP) and Net Benefit Increase (NBI) of biogas plant’s impact on livelihood were studied in Bangladesh. Respondents belonging to 30- to 50-year age group were 54%, those belonging to the business group were 24%, up to higher secondary education were 36%, those having an average family size of 4 (3.78) were 36%, those belonging to middle-income (1,00,001–1,50,000 Bangladesh Taka, Tk.) group were 8%, and those belonging to high-income (>1,50,000 Tk.) group were 92%, out of the surveyed sample. Increase in knowledge, skill, work capacity, nutrition, health and education were found in 58, 64, 70, 78 and 66%, and increase in leadership, women liberation, common rules, mutual support, networking connections were found in 54, 60, 52, 64 and 62% with the use of biogas [11].

A model was developed for making detailed inventories of producing electricity from biogas. Types of biogas systems studied were organic waste landfill-based and dairy cattle waste-based. Life cycle assessment (LCA) showed different sub-stages of the systems. It was concluded that LCA enables producers, decision-makers and government agencies to recognize and improve opportunity areas of the technology [12].

Convenient usage of both biochemical (anaerobic digestion) and thermo-chemical conversion technologies, the energy production at farms can become surplus by using the total biomass produced. Agricultural economy may recover and sustainable regional development may become feasible. A combination of renewable technologies in energy supply for rural livelihood sustainability has a promising potential.

With its numerous rewards for rural households empowering and making their livelihood sustainable, a review discussion was made on the research work in gasification of biomass for recommending the sustainable solution with technologies, viz. biochemical and thermal gasification and their costs when accounting for certain conditions; viz. family size, livelihood cost among others along with users/stakeholders interests. An assessment was made on the socioeconomic effects of biogas plants on the livelihood security of rural households in the selected villages of Punjab State of India.

2. Biochemical gasification

In a country like India, where about 68.8% of the total population lives in rural areas [22], one of the alternative energy source is biogas. Biogas, a product of anaerobic digestion in the absence of air of cellulosic biomass, like cattle dung, poultry droppings, pig excreta, human excreta, crop residues etc., abundantly available in rural areas, is a suitable fuel for providing heat and operating stationary engines. This anaerobic digestion results in the production biogas, a mixture of combustible gases, mostly containing 50–60% methane, 30–40% carbon dioxide, 1–5% hydrogen and traces of nitrogen, hydrogen sulphide, oxygen, water vapors, etc. [23]. Anaerobic digestion not only provides valuable fuels and enhances the fertilizer value of the waste but also provides a conventional, safe, aesthetical and economical waste disposal method. The biogas plant design is unswervingly linked to its hydraulic retention time (HRT). The HRT is the time span (days) for which a mixture of water and cattle dung remains inside an enclosed digester for gas generation and after HRT, its biological capability is diminished. The HRTs of biogas plants differ based on their location in India. Most of the plains in India, including Punjab, have 40 days of HRT.

2.1 Design models of biogas plant

Biogas plants are mostly categorized as batch type, and continuous type. Batch-type biogas plants are appropriate where daily supplies of raw waste materials are difficult to obtain and are most suitable for digestion of crop biomass. In continuous-type biogas plants, supply of gas is continuous, and the digester is fed with biomass regularly. These types of biogas plants may be single-stage, double or multiple-stage. There are two basic continuous type biogas plants designs that are popular in India; viz., floating drum type, and fixed dome type. Popular models in floating drum type are ‘Khadi’ and Village Industry Commission (KVIC) model, whereas, ‘Janta’ model, and ‘Deenbandhu’ model are popular among fixed dome types [5].

2.2 Selection of size of biogas plant

The size or capacity is the quantity of biogas produced in cubic metres (m³) on 24 24-hour basis. Quantity of cattle dung available or number of family members in a household quantifies the biogas plant capacity. As a thumb rule, 1 kg of cattle dung can produce approximately 0.04 m³ of biogas, or 0.34–0.42 m³ of biogas is required per person for cooking food. Either of these criteria can be used for finding the other. Therefore, it is presumed that, as the biological process sets in, 1 m³ of biogas is produced from 25 kg of cattle dung. As a matter of fact, as ordinary cattle, depending on a number of factors, produce about 10–20 kg of dung [23]. The plant size calculations, based on the above data, are shown in Table 1.

Sr. no.	Capacity of biogas plant (m^3)	No. of animals required	Quantity of dung required (kg)	Cooking for number of persons
1	2	3–4	50	4–5
2	3	5–6	75	7–8
3	4	7–8	100	10–11
4	6	10–12	150	4–16

Table 1.

Number of persons served, requirement of dung and number of animals for different sizes of biogas plants.

2.3 Cost of installation of biogas plants

The costs of civil construction including the cost of steel required for each type of biogas plants was taken as per criteria adopted [4]. The cost of installation of different family-size biogas plants that includes material and labour costs at the prevalent market rates is given in Table 2.

Sr. no.	Biogas plant models	Plant capacity
		2 m^3	3 m^3	4 m^3	6 m^3
1	KVIC type	30,000	37,000	43,000	55,000
2	‘Janta’ type	26,000	30,000	32,000	40,000
3	‘Deenbandhu’ type	20,000	25,000	30,000	35,000

Table 2.

Installation costs of different types of biogas plants.

The Indian government provides a fixed amount of financial assistance, for promoting the use of biogas, through the state energy development agency (PEDA, Punjab Energy Development Agency in case of Punjab state) in Indian rupees, as given in Table 3 [24].

Sr. no.	Regions and beneficiary category	Capacity of biogas plants in cubic metre/day (INR per plant)
		1	2–4	6	8–10	15	20–25
1	(a) Hilly/North Eastern Region States; (b) Island; and; (c) Scheduled Castes (SC)/Scheduled Tribes (ST)	17,000	22,000	29,250	34,000	63,250	70,400
2	All other States and Categories	9800	14,350	22,750	23,000	37,950	52,800
3	Additional fixed Subsidy for
	(i) Biogas plant if linked with sanitary toilet	1600	1600	1600	1600	NA	NA
	(ii) Biogas plant if linked with approved Biogas slurry filter unit	1600	1600	1600	1600	1600	1600
4	Turnkey job fee for construction, supervision, commissioning and free operation and maintenance warranty for 5 years of trouble-free operations	INR 3000 per plant for 1–10 m^3 and INR 5000 per plant for 15–25 m^3 size. This turnkey job fee is applicable only for plants involving onsite construction such as fixed dome design ‘Deenbandhu’ Model, floating gasholder. KVIC Model. Turnkey job fees will not be eligible for prefabricated/manufactured biogas plants.

Table 3.

Central financial assistance (CFA) under the biogas programme.

NA: Not applicable.

3. Thermo-chemical gasification

Thermal gasification includes incomplete burning (oxidation in limited air amount/oxidant) and reduction processes of biomass to produce combustible mixture of gases known as producer gas. In a characteristic incineration procedure usually oxygen is in excess, whereas in gasification route fuel is in excess. The combustion yields, mainly carbon dioxide, water vapor, nitrogen, carbon monoxide, hydrogen, etc., and these are passed through the burning layer of charcoal for the reduction process to occur. During this stage, both carbon dioxide (CO₂) and water vapor oxidize the char to form carbon monoxide (CO), hydrogen (H₂) and methane (CH₄). A typical composition of the gas obtained from wood gasification on volumetric basis is as; CO is 18–22%, H₂ is 13–19%, CH₄ is 1–5%, heavy hydrocarbons is 0.2–0.4%, CO₂ is 9–12%, nitrogen (N₂) is 45–55% and water vapor at 4%. Gasifiers are broadly classified into (i) updraft, (ii) downdraft and (iii) fluidized types [5].

3.1 Selection of gasifiers

An extensive review of gasifier manufacturers identified 50 producers proposing ‘commercial’ gasification plants; out of that, 75% were in the downdraft category, 20% were in the fluidized bed category, 2.5% were in the updraft category and 2.5% were of different other categories [25]. While very small facts were provided on authentic hours of working experience, gasifier’s turn-down ratios, efficiencies, emissions and price features. In all, none of the gasifier producers supplied the full guarantee for the practical working of their technology [26].

For meeting the thermal and electrical requirements of rural households, downdraft gasifiers have been developed in the range of 5–60 kW, as given in Table 4. A 5 kW gasifier will be suitable for a family of 4–6 persons. After cleaning producer gas through filters, diesel engine gen-sets can be operated, and up to 70% of diesel savings can be made. Annual savings of up to INR 20,000 can be achieved by operating the system for 1500 hours, and one can recover the cost of the gasification system in 3 years [27].

Sr. no.	Capacity (kW)	Application	Fuel and its size (mm)
1	5	Water pumping	Rice Husk, As such
2	10	Water pumping or electricity generation	Wood chips, maize cobs, cotton and pulses sticks, 50
3	25	Electricity generation	Wood chips, maize cobs, cotton and pulses sticks, 100
4	40	Electricity generation	Wood chips, maize cobs, cotton and pulses sticks, 120
5	60	Electricity generation	Wood chips, maize cobs, cotton and pulses sticks, 150

Table 4.

Performance of biomass gasifier-diesel engine system*.

^*

Moisture content of fuel: Less than 15%; Engine de-rating: 15–25%; Diesel replacement: 70–75%; and Fuel consumption: 1–1.3 kg/kWh.

The central financial assistance (CFA) is provided by the Government of India through the state energy development agency PEDA in the form of back ended subsidy for installation of waste-to-energy biomass gasifier projects for recovery of energy from urban, industrial, agricultural waste/residues and municipal solid wastes. The details of the fixed amount of financial assistance given in the biomass gasifier programme are given in Table 5 [28].

Sr. no.	Items	Pattern of assistance (INR)
1.	Biomass gasifier for captive power applications in industries and other institutions	Electrical – INR 2500 per kWe with dual fuel engines
2.	Distributed/off-grid power for villages and up to 2 MW Grid-connected power projects	Electrical – INR 15,000 per kWe with 100% gas engines
3.	Biomass gasifier for captive thermal applications in industries and other institutions	Thermal – INR 2.0 lakh per 300 kWth for thermal use

Table 5.

The pattern of central financial assistance for biomass gasifiers.

4. Technology specific barriers

Gasification of biomass, as discussed, is intricate and diverges by several means, for example, feed properties desirable (i.e. farming/forestry biomass, cattle dung, etc.), span of lifetime (long, medium and short-term), natures of usage (cooking, thermal, etc.), and upkeep required (monthly, weekly and daily). Discrepancies in the type of biomass gasification know-how, practical performance doubts, market inadequacies such as controlled energy sector, high investment and transaction costs, restricted access, lack of information and competition, trade barriers etc., economic and financial reasons such as non-viable, need for incentives, long payback periods, small market size, capital costs, lack of access to capital, credit, financial institutions, high up-front cost to investors etc. Institutional barriers such as deficiency of organizations to propagate information, permitted/monitoring outline, difficulties in realizing monetary inducements, stakeholder’s interest and choice building, clash of welfares, deficiency of research and development, private-sector involvement, specialized establishments, etc. Procedural barriers such as the absence of typical codes and documentation, expert workforces, training services, operation and maintenance services, businesspersons, structural limitations, unreliable products, etc. Societal obstacles include the absence of customer recognition and social acceptance, and other incidental barriers such as uncertain government policies, high-risk perception and environmental conditions. However, policies and programmes initiated by the government have made an attempt to address some of these barriers to propagating the technology to rural masses. The policy opportunities in overpowering such obstacles for the advancement comprise research and development aimed at reducing price, consistent working, investment grants, extensive demonstrations, work-based monetary inducements, reasonable charges instead of biomass power, performance assurances, formation of a big linkage of businesspersons and trained individuals for the manufacture, set up, upkeep of skill structures, training and awareness are the main concern [23, 25].

5. Assessment methodology

A review was piloted in designated villages/communities of district Patiala of Punjab state of India. A feedback form was prepared for the collection of essential data associated with farmer land holding, biogas plant set up or not, its kind, capacity, year of installation, cattle heads, fuel type used in the household kitchen, biogas usage and other purposes. The socioeconomic contemplations like savings in terms of replacing conventional fuel by biogas were also included in survey proforma. The data was collected by making personal contacts with the individual farmers in selected villages.

To understand the socioeconomic characteristics of domestic level use of biogas plants, the questionnaire was set with objectives of knowing the household income from different sources (like agricultural land contracts, business, private or government service and others, if any). Data on cultivatable area where slurry was used as manure, installation cost of biogas plants and their capacity, and any subsidy if given by the government to install the biogas plant were also noted. The data collection was also done to know the difference between families’ livelihoods: those having biogas plants and others with no biogas plants. The survey also focused on amount of savings made by people who owned the biogas plant by means of conventional fuel savings (i.e. fuel wood, liquefied petroleum (LPG) gas cylinders and dung cakes) made with the usage of biogas in kitchen.

The influences of the use of biogas at domestic level were considered in terms of by-product (spent slurry) use as manure with decrease, if any, in the applicable dose of chemical fertilizers noted in survey proforma for calculating the savings. The greenhouse gas emission reduction by usage of cattle dung, which is otherwise dumped in open, was also calculated on a yearly basis as described in [29, 30]. The amount of methane and ammonia gases released in kg/year is estimated by multiplying number of cattle by 112 for kg of methane and adding with multiple of number of cattle to 40 for kg of ammonia gas release estimation.

6. Assessment results and discussion

Data was collected from 45 farming households in 15 different communities of district Patiala. The communities covered in the study were Naraingarh, Gulhar, Sagra, Kullar, Noorpur, Majri Palak, Manjoli, Bhedpura, Tuga, Namada, Jagatpura, Bhima Khedi, Fatehgarh, Jafarpur and Bakhshi Wala.

6.1 Family details

The detail of family members of different households that had biogas plants and others that did not have or had non-working biogas plants is given in Table 6.

Family size	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Small (<5)	7	25.0	1	5.9
Medium (5–7)	16	57.1	12	70.6
Large (>7)	5	17.9	4	23.5
Total	28	100.0	17	100.0
Maximum	10		11
Minimum	3		3
Average	6		6

Table 6.

Detail of family members of surveyed farmers.

About 31 farmers had biogas plants for domestic use, out of which 28 plants were found in working conditions and three plants were not working. The average number of members in the family of surveyed farmers were six for both households having and not having biogas plants. All farmers under the survey work had installed ‘Deenbandhu’ type biogas plant of 6 m³ capacity. All farmers were using the biogas in their household kitchens for cooking purposes. Farmers were also disposing of the surplus cattle dung in pits where biogas plant slurry had been kept. About 12 farmers were also making dung cakes. The surveyed households had similar human resources, most of which were of medium family size.

6.2 Socioeconomic considerations

The surveyed household’s cultivable land holdings, overall income and earnings from farming are given in Tables 7–9.

Land holdings (acre)	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Marginal (<1)	2	07.2	2	11.8
Small (1–2)	3	10.7	1	05.9
Semi-med (2–4)	11	39.3	10	58.8
Medium (4–10)	9	32.1	3	17.6
Large (>10)	3	10.7	1	05.9
Total	28	100.0	17	100.0
Maximum	55		26
Minimum	2		2
Average	12.04		8.12

Table 7.

Land holdings of surveyed farmers.

Income range (Rs.)	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Less than 2 lakh	0	0.0	0	0.0
2–5 lakh	7	25.0	7	41.2
5–10 lakh	15	53.6	9	52.9
10–15 lakh	3	10.7	0	0.0
More than 15 lakh	3	10.7	1	5.9
Total	28	100.0	17	100.0
Maximum	27,50,000		21,00,000
Minimum	2,50,000		2,50,000
Average	8,32,143		6,11,176

Table 8.

Details of overall income from all sources of surveyed farmers.

Income range (Rs.)	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Less than 2 lakh	4	14.3	2	11.8
2–5 lakh	13	46.5	11	64.7
5–10 lakh	6	21.4	3	17.6
10–15 lakh	3	10.7	1	5.9
More than 15 lakh	2	7.1	0	0.0
Total	28	100.0	17	100.0
Maximum	27,50,000		13,00,000
Minimum	1,00,000		1,00,000
Average	5,85,714		4,05,882

Table 9.

Details of income from farm land of surveyed farmers.

The average land holding was 12.04 acres and 8.12 acres among households having and not having biogas plants, respectively. At the same time, maximum percentage of farmers belong to semi-medium category in both groups. The households having biogas plants were holding a comparatively larger farm area as compared to households not having biogas plants.

The average earnings from all sources of households having biogas plants was around INR 8,32,143, and of households not having biogas plants was around INR 6,11,175. Most of the households fall in INR 5–10 Lakh annual income category among both the groups. Whereas the average earnings from farmland of households having biogas plants was around INR 5,85,714, and of households not having biogas plants was around INR 4,05,882. Most of the households fall in INR 2–5 Lakh annual agricultural income category among both the groups. The households having biogas plants were earning comparatively better from farms and other works as compared to households not having biogas plants.

Details of other remunerative works and income generation among the surveyed farmers are given in Tables 10 and 11.

Other works	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Service	9	56.3	6	66.7
Business	6	37.5	3	33.3
Others	1	6.3	0	0.0
Total	16	100.0	9	100.0

Table 10.

Detail other remunerative works done by the surveyed households.

Other works	Income of households having biogas plants (Rs.)			Income of households not having biogas plants (Rs.)
	Maximum	Minimum	Average	Maximum	Minimum	Average
Service	10,00,000	1,00,000	4,94,444	8,00,000	1,50,000	3,90,000
Business	7,00,000	1,50,000	3,91,667	5,00,000	3,00,000	3,83,333

Table 11.

Income earned from other works by the surveyed households.

About 16 households having biogas plants and nine households without biogas plants were engaged in government/private service, business and other works. The households with biogas plants were more business-oriented, whereas those without biogas plants were more service-oriented.

The average income earned from service and business of households with biogas plants was INR 4,94,444 and 3,91,667, respectively. as compared to INR 3,90,000 and 3,83,333 for households without biogas plants. The households having biogas plants were comparatively earning better from other works than households without biogas plants.

The details of monthly and yearly livelihood costs and annual conventional fuel (wood, cooking ga and dung cakes) savings made using biogas by the surveyed farming household are given in Table 12.

Livelihood cost (Rs.)	Households having biogas plants		Households not having biogas plants
	Numbers	Percentage	Numbers	Percentage
Less than 1 lakh	4	14.3	0	0.0
1–2 lakh	14	50.0	11	64.7
2–3 lakh	10	35.7	6	35.3
More than 3 lakh	0	0.0	0	0.0
Total	28	100.0	17	100.0
Maximum	3,00,000		3,00,000
Minimum	60,000		1,08,000
Average	1,66,714		1,83,529

Table 12.

The total cost of livelihood of the surveyed households.

The average annual cost of livelihood of households with biogas plants was INR 1,66,714. In contrast, it was found that the average annual cost of livelihood of farmers who did not have biogas plants at their houses was INR 1,83,529. The farming households with biogas plants were less spendthrift as compared to households without biogas plants.

6.3 Impact of biogas plants on livelihood of rural people

The details of annual savings made by using biogas in kitchens in terms of fuel wood, cooking gas cylinders and dung cakes in different households with biogas plants are given in Table 13.

Details	Fuel wood saving (kg)	LPG cylinders (No.)	Dung cakes (kg)	Total savings (Rs.)
Maximum	3000	12	600	15,450
Minimum	500	5	200	4200
Average	1389	9	440	10,295

Table 13.

Annual savings made by using biogas in kitchens.

The average annual fuel savings made by the surveyed families were about 1389 kg of wood and about nine cooking gas cylinders. Five farming households were also saving about 440 kg of dung cakes. The average annual fuel savings by the surveyed families was INR 10,295.

The farming households with biogas plants also used dried biogas plant slurry as manure, and farming households without biogas plants used cattle dung as farm yard manure. The details of total chemical fertilizer (Urea) savings made and paddy yield (in quintals, q) gained by the farming households are given in Tables 14 and 15.

Details	Cultivation area (acre)	Urea fertilizer saving (kg/acre)	Yield gain (q/acre)	Total benefits (Rs.)
Maximum	10	65	2.5	52,120
Minimum	2	30	1	4330
Average	4.7	48.0	1.8	18,598

Table 14.

Savings from chemical fertilizers and yield increase by using biogas plant slurry as manure in paddy cultivation.

Details	Cultivation area (acre)	Urea fertilizer saving (kg/acre)	Yield gain (q/acre)	Total benefits (Rs./acre)
Maximum	8	70	3	33,967
Minimum	1	45	1.3	5275
Average	4.4	57.1	2.1	19,078

Table 15.

Savings from chemical fertilizers and increase in crop yield by using cattle dung as manure in paddy cultivation.

Surveyed farmers used dried slurry as farm yard manure (FYM) on 4.7 acres, on average. The parameters taken into consideration to convert the quantity of fertilizers saved and increase in production into money with the rate of urea was Rs.2.5 per kg and rate of the paddy was INR 2040 per quintal (average rate of course and fine varieties). The average increase in yield by using dried biogas plant slurry as manure was 1.8 quintal per acre, and 48.0 kg of fertilizer was saved per acre. The average money saved by the use of biogas plant slurry was equal to INR 3957 per acre.

With the use of cattle dung as FYM alone, chemical fertilizers (Urea) savings were also made on about 4.4 acres, on average, by farming households without biogas plants. It was also found that average increase in yield by using FYM was 2.1 quintal per acre, and 57.1 kg of fertilizer was saved per acre. The average money saved by the usage of cattle dung as FYM alone was found to be equal to INR 4336 per acre.

The use of biogas plant slurry as manure was not found to be better regarding urea fertilizer savings and crop yield gain than cattle dung use as FYM in paddy crop cultivation.

6.4 Impact of biogas plants on environment protection

The details of cattle head and quantity of greenhouse gas (methane and ammonia) emission reduction by the farming households with biogas plants are given in Table 16.

Details	Emission reduction by biogas plants (kg/year)		Emission by open disposal of cattle dung (kg/year)
	Ammonia	Methane	Ammonia	Methane
Maximum	520	1456	320	896
Minimum	120	336	40	112
Average	267	755	176	494

Table 16.

Details of greenhouse gas emission reduction by biogas plants and emissions from open disposal of cattle dung by the surveyed households.

With the use of biogas plants, the farmers prevented the emission of methane and ammonia from the open disposal of cattle dung. The average amount of ammonia and methane emissions contained yearly were about 267 and 755 kg, respectively. Whereas, with the open disposal of cattle dung by household not having biogas plants, the average yearly ammonia and methane emissions were about 176 and 494 kg, respectively. This means biogas plant helps greatly in protecting the environment from greenhouse gases.

7. Conclusions

Biogas plants were successful in the outer peripheries of villages or in fields. Biogas can be burnt for cooking or lighting the house. It can also be used to run internal combustion/gas engines to generate motive power or generate electricity. Two types of economic benefits can be taken, i.e., one is it saves the energy cost to be purchased, and the other is it can earn extra money by selling to the neighbors. Owing to the problems of land availability and provisions of required feedstock, biogas plants are less successful in the interiors of communities.

Thermal gasification of biomass is an encouraging technology to replace the usage of conventional fuels and to decrease fossil CO₂ release into the atmosphere. A great potential exists with this type of renewable energy: it can consume extensive kinds of materials as feed input for energy production. Also, it can produce numerous chemicals and fuels. Abundant quantities of crop/forestry-based biomass are available, and it can be optimally used for the thermal and power requirements of communities by empowering co-operatives with the technical know-how of the technology along with convincing incentives that may change the overall energy scenario at the rural level.

The assessment study showed that the average family members of surveyed household were 6, each and the average cultivable land was 12.04 acres and 8.12 acres among households having and not having biogas plants, respectively. Out of the 45 households surveyed, 13 have income from government/private service and 7 farmers were running some business. The income of the surveyed households varied from INR 2,50,000 to Rs.27,50,000. The average annual fuel savings made by the surveyed families were about 1389 kg of wood, and about nine cooking gas cylinders. Five farming households saved about 440 kg of dung cakes. The average annual fuel savings by the surveyed families was Rs.10,295. The average annual cost of livelihood of the farmers who have and did not have biogas plants at their houses was INR 1,66,714 and 1,83,529, respectively. The farmers, having biogas plants, used dried slurry as FYM on about 4.7 acres, and the average increase in yield was 1.8 quintals per acre, and 48 kg of chemical fertilizer (Urea) was also saved per acre. The average money saved by the use of biogas plant slurry as FYM was about INR 3957 per acre. The farming households without biogas plants also saved chemical fertilizers (Urea) by using cattle dung as FYM on about 4.4 acres. The average increase in yield by using FYM was 2.1 quintal per acre, and 57.1 kg of chemical fertilizer was saved per acre. The money saved was around INR 4336 per acre. The average number of cattle heads owned by the surveyed farmers was 7. The biogas plant farmers prevented the emission of methane and ammonia to the tune of about 755 kg of methane and 267 kg of ammonia on an average per year. The average amount of ammonia and methane released to the atmosphere, by open disposal of cattle dung were about 176 and 494 kg, respectively, of households not having biogas plants.

Acknowledgments

The author duly acknowledges Er. Jatinder Singh for providing basic information regarding the use of biogas plants at farmer’s level that was collected during the course of his graduate project work.

Conflict of interest

The authors declare no conflict of interest.