Bioenergy Resources -Integration Approach for a Self Sufficient Energy Village
Introduction:
In the present energy scenario most of the population lives in rural areas with short of electricity supply, which is the main obstacle in the development of rural areas. The increasing consumption of conventional fuels coupled with environmental degradation has led to the development of renewable energy sources. Hence, it is necessary to supply renewable electricity to these areas in decentralized mode. Renewable energy sources are the most feasible solutions, as these are unlimited, inexhaustible and environment friendly sustainable resources. The rural villages have substantial renewable energy sources like biomass, solar, wind etc. The problem caused by variable nature of these resources can be partially overcome by either installing individual large renewable power plant or adding energy storage and reconversion facilities and / or by integration. (Kanse Patil et al. 2008, Rajvanshi A.K. 2002, Ravindranath N.H.et al. 2004, and Shukla P.R. 2008)
- Assessment of available bio resources is helpful in revealing its status and helps in taking conservation measures and ensures a sustained supply to meet the energy demand. Assessment of bioenergy potential can be theoretical, technical or economic. Sukla (2008) reported that despite rapid growth of commercial energy, biomass remains principle energy source in rural and traditional sectors and contributes a third of India's energy. For development of rural area one of the solution will be the utilization of sources, that lies within a village itself that is non commercial energy sources. These sources can be harnessed efficiently by adopting gasifier, biogas plants, solar collectors, tree plantation etc. which will provide lightning for home and streets, fuel for cooking and water heating motive power, power for pumps for irrigation etc. for efficient utilization of non commercial energy resources and exploitation of new one for rural area proper planning is essential. ( Chauhan S. 2008, Chauhan S. et al. 2004, Ericsson et al. 2006, Esteban L.S. et al. 2008, Fischer G. et al. 2001 and Fuchs, M.R.et al. 2005 )
This work has emphases mainly on to find out the potential of agrowaste, livestock waste and biomass available in the village for energy generation. Keeping above views in mind the study was taken with objectives to assess bioresources potential of village 'Nimbhora' and suggest renewable energy planning for self sufficient energy village.
MATERIALS AND METHOD
Biomass resource assessment
Field surveys based on household and direct interview methods was carried out in the village to collect potential available of biomass. Biomass energy supply was based primarily on land use statistics and yield of various crops, plantation and forest biomass productivities and the animal waste available.
Village information
The study was being conducted at Nimbhora in Akola District of Maharashtra State. It is 20 km away from Akola. The major crops grown in the village were cotton, sorghum, soybean, green gram, pigeonpea, gram etc. Total population of the village is 951 consisting of 170 households. The detail information of each family was obtained by personal interaction with the people. It was observed that total geographical area in Nimobhora was 1443.38 acre and area under cultivation is 1352.8 acre. All the cultivable area was rainfed and there was no facility of irrigation in the area.
Biomass from agricultural and residues
The cultivated area and the biomass yield of each crop influence the biomass potential from agricultural residues. The yield of a crop according to season and variety across an area was obtained by a averaging the yields of the previous years. The energy equivalent of these residues was taken based on what would be obtained if they would be subjected to the most energy efficient transformation processes. Portion of the residues available were used as fuel, while some used as fodder, and the rest left behind in the field for nutrient recycling. Energy from agriculture residues (E1).
E1 = Energy from agriculture residue (kcal)
= Total agro residue production - consumption of agro residue
Table 1: Grain to straw ratio of various crops .
Crop
Grain / Straw
Cotton
3 t/ha
Soybean
1:1
Jawar
1:3
Pigeonpea
1:4
Gram
1:1.3
Green gram
1: 1.3
Maize
1:4
Sunflower
1:2
Source : Dubey et al. (2009)
Heat value of various crops were taken in range of 3000-3650 kcal/kg The heat value for cotton, pigeonpea and sunflower were taken as 3500, 3000 and 3650 kcal/kg respectively.
Biomass from forest lands
The biomass potential of the forests is dependent on the type of forest and its distribution cover. The biomass production varies with the type of forest. The forest wood fuel collected annually by the household from the adjoining forest area was taken with the energy equivalent. Total energy from forests (E2) was computed by
E2 =Energy from forests (kcal)
=Annual wood collected - Consumption of wood in household activates
Biomass from live stock (animals)
The livestock population of cattle, buffalo, sheep and goat was collected from the personal interaction with the respondents. It was taken as 12-15 kg/animal/day for buffalo, 3.0-7.5 kg/animal/day for cattle, 0.1 kg/animal/day for sheep and goat. The total dung produced annually was calculated by multiplication of the animal dung production per year and the number of head of different animals. Assuming 0.036-0.042 m3 biogas yields per kg of cattle/buffalo dung, the total quantity of gas available was estimated. Total energy from livestock (E3) was computed by
E3 = Energy from livestock (kcal)
= Total cow dung collected - direct dung consumption through cake
Table 2 : Dung yield, biogas yield and energy equivalent for livestock.
Livestock type
Case
Dung yield kg/animal/ day
Biogas yield m3
Energy equivalent kcal/m3
Buffalo
High
15
0.042
5300
Low
10
0.036
5300
Cattle
High
7.5
0.042
5300
Low
3
0.036
5300
Goat
High
0.1
0.042
5300
Low
0.1
0.036
5300
Sheep
High
0.1
0.042
5300
Low
0.1
0.036
5300
Total biomass sources available from various sectors was computed by aggregating the energy computed from individual sectors (forestry, agriculture residues, livestock) and given by
Energy availability = ? (E1 + E2 + E3)
Energy utilization pattern of village
In this study, the energy consumption patterns of the village was studied from the survey. All socio economic activities related to the energy use was collected. The use of energy in houses, village lightning system, use of diesel in tractor allied machineries, use of petrol for two wheeler and small agro processing units was collected.
Energy Density of village
The energy density of the village was calculated for knowing the energy potential available per hectare. The total possible energy generation from all the biomass sources was determined by using the heat value of the biomass. This means that the energy density is the total possible energy available through biomass sources in a particular area. The computational formula for the calculation of energy density was taken as
Total possible energy generation (kWh)
ED = --------------------------------------------------------------
Total geographical area of village (ha)
Where, ED is energy density in kWh per hectare
Biomass power generator size selection
The sizes of the biomass power generator was decided on the basis of the quantities of biomass available and the overall conversion efficiency computed and decided by means of the following formulae.
Energy = Quantity of x Heating x Conversion
generation (kWh) biomass value efficiency
This relation mainly emphasized on the total energy generation of the system. The size of power generator (crop residue based) can be calculated by using following relationship.
Energy generation (kWh)
Power generator size (kW) = ----------------------------------------------
Yearly operating hours (h)
The sizes for the digester based power generation was computed by using the following relation:
Energy generation (kWh)= Biogas x heating value x conversion efficiency
The operating hours per day and thereby as whole year for digester based power generation system was decided for calculation. The size of power generator of biogas operated was calculated by using following relationship.
Energy generation (kWh)
Power generator size (kW) = -----------------------------------------
Yearly operating hours (h)
RESULTS AND DISCUSSION
Bioresources potential for village Nimbhora was assessed and on the basis of surplus availability renewable energy planning for self sufficient energy village was carried out and discussed in this chapter.
Status of biomass sources in village
The biomass potential, demand and energy use pattern in the villages was calculated from the available data. The bulk of dung was obtained in the village from bullock, cow, buffalo and calf 189, 123, 25 and 113 in numbers respectively.
It was observed that 11644.5 q dung was available in village Nimbhora and among the agricultural waste cotton residues was major source of biomass contributing about 5531.8 q (Table 3 and Fig.1). Pigeonpea and sunflower were also important biomass sources while planning the self energy strategy of the respective village.
Table 3 : Status of biomass in village Nimbhora
Sr. No.
Biomass source
Total quantity (q)
1
Dung
11644.5
2
Cotton
5531.8
3
Pigeonpea
503.56
4
Sorghum
3827.1
5
Green gram
339
6
Sunflower
471.5
7
Gram
718.7
8
Soybean
1139.62
9
Maize
1899
Fig. 1 : Status of biomass in village Nimbhora
Livestock bio energy sources
In this study, information about all the bioenergy resources was collected and presented in table 4 reveals the information about the production and use of the animal dung in the village. It was found that 11644.5 q of cattle dung was available in one year with a consumption of 2973 q and surplus available 8670 q, which help to fulfill the demand of villages by using the suitable renewable energy conversion system.
Table 4: Use and surplus of the cattle dung in the village
No. of animals
Dung available (q)
Total consumption (q)
Surplus (q)
526
11644.5
2973
8671.5
Collection and surplus of bio resources in village
In the selected village all biomass sources were collected for the determination of the biomass generation capacity. Simultaneously the consumption of the bio resources from the personal interaction with the villages was collected. The demands of the energy required for cooking/ domestic sector was satisfied by using the pigeonpea, cotton and sunflower residues. A large amount of residue were found surplus in the villages. Cattle dung and cotton residues as a biomass were found major surplus in the village.
Table 5 depict information of the yearly availability of agricultural residue, production, consumption and surplus in the village. It was found that 8671.5 q cattle dung and among agro residue 1197.5 q cotton residue were found surplus (Fig. 2).
Table 5. Collection, consumption and surplus of energy in village
Biomass source
Collection (q)
Consumption (q)
Surplus (q)
Cattle dung
11644.5
2973
8671.5
Cotton
5531.8
4334.3
1197.5
Soybean
1139.6
1139.6
0
Sorghum
3827.1
3827.1
0
Pigeonpea
503.5
426
77.5
Maize
1899.2
1899.2
0
Gram
718.74
718.74
0
Sunflower
471.5
347
124.5
Fig. 2: Collection, consumption and surplus of energy in village
Consumption of bioresources and energy in village
Detailed summary of energy consumption for various major activities (Biomass and allied energy) was carried out in this investigation. Table 6 reveals the information about the consumption of electricity of households, processing mills, consumption through street lamps, school, gram panchayat, temples, post office etc. There were only three floor grinding mills available in the village. There were 170 households in the village. Since the soil of village Nimbhora comes under saline track, most of the farming was rainfed and there was no irrigation facility.
Table 6 : Yearly consumption of electricity in the village Nimbhora
Household kWh (A)
Agro processing mill kWh (B)
School street lamp temple and various offices in village (C) kWh
Total A + B+ C (kWh)
85410
10585
5372.8
101367.8
Fig. 3 : Yearly consumption of electricity in the village Nimbhora
Table 6 shows the outlook of electrical energy consumption of various operational uses in the village. It was observed that yearly consumption of electrical energy in village comes to be 101367.8 kWh (Fig. 3).
Nearly 7800 ? diesel was consumed annually for the tractor operation and 4562 ? of petrol required for vehicles available in the village. The villagers used 10 motorcycles for conveyance. Kerosene and LPG was used as a fuel for lighting and cooking purpose in the village which is depicted in Table 7.
Table 7 : Yearly consumption of liquid fuel and LPG in Nimbhora
Parameter
Number
Diesel ?
Petrol ?
Kerosene ?
LPG cylinders or refills
Motor cycle
10
-
4562
-
-
Tractor
3
7800
-
-
-
Cooking and lighting
-
-
-
5352
-
Cooking
-
-
-
-
187
Available energy from biomass
The information about the quantity of biomass resources available in the village Nimbhora is given in Table 8 . Agricultural residue such as cotton, pigeonpea, soybean and cattle dung etc were also the major available resources of biomass in the village. For calculating energy generation capacity of biomass resources, calorific values of the biomass were considered (Fig.4). Considering all the available surplus quantity of biomass, total energy generation in the village was found to be 727539.82 kWh.
Table 8 : Available bio energy from surplus biomass resources
Biomass source
Quantity (q)
Total possible energy available, kcal
Energy generation kWh
Cotton
1197.5
419097000
487322
Pigeonpea
77.5
23268000
27055.8
Sunflower
124.5
45442500
52840.11
Dung
8671.5
137876850
160321.91
Total possible energy generation kWh
727539.82 kWh
Fig. 4: Available bio energy from surplus biomass resources
It realized that electrical energy consumption was found less than the bioresources energy available in the village. The ratio of energy generation from bioresource to the energy consumption of the village was around 7:1.
It means that the energy used by the villagers was found much less than the biomass generated in the village. It is also realized that gasification based electrical energy generation system and biogas electrical energy generation project will be possible alternative for generating electrical energy in the village. A proposed renewable energy system will not have any impact on the ecological cycle of the village bioresources.
Biomass gasifier and digester
Power generation capacity from agro residues
The planning of the suitable system for energy generation at village level was the first step. Proper planning minimizes the cost of system and the future cost of the energy generation. The surplus biomass availale in the village was cotton residue, pigeon pea residue sunflower residues and cattle dung. The overall conversion efficiency of producer gas based electrical energy production was reported 17%. The total installation capacity of power generation based on gasifier system was found to be 35 kW (Table 9).
Table 9 : Possible energy generation with installed power capacity of gasifier.
Energy from cotton, pigeon pea and sunflower residue kWh
Total installed capacity
96427.00
35
Power generation capacity from cattle waste
The cattle dung was a main vital source for the bio power generation in the village. The total quantity of surplus cattle dung available in village was 8671.5 q per year. The overall conversion efficiency of biogas based electrical energy production was reported 25 % (Biogas to electrical energy). Considering surplus cattle dung a 15 kW size of digester based power generator was estimated for village Nimbhora.
Table 10 : Possible energy generation with installed power capacity of digester.
Cattle dung surplus (q)
Energy (kWh)
Total installed capacity kW
8671.5
40080.47
15
Biomass generation of village
The sizes of the power generation have been decided with the total energy generation in a year. The table 4.9 insight the overall picture of the energy generation. Considering the conversion efficiency of the gasification and digester based power generation system for the predicted green energy in a year. The total energy generation from the possible installed capacity of generator was found to be 136507.47 kWh.
Table 4.9 : Sizes of biomass power generator with one year energy generation.
Gasifier kW
Digester kW
Energy gasifier kWh
Energy digester kWh
Total install power kW
Total energy kWh
35
15
96427
40080.47
45
136507.47
CONCLUSIONS
The study revealed that the village was having considerable surplus of bioresources. Among the bioresources, cotton residue and cattle dung contributed significantly toward surplus bioenergy. Based on the bioenergy status, feasible management and technical options was discussed which would helpful in optimizing the available bioenergy and in building a sustainable energy. The proposed renewable energy system will minimize the burden on the existing resources so as to become self sufficient energy village. In village Nimbhora, bioenergy availability and demand of energy computation showed that the village could be self sufficient in respect to energy. It was found that surplus cotton residue available with quantity 1197.5 q in one year and therefore, contributed the main bioresources in the village. A large quantity of cattle dung was available in village. The availability of the cattle dung was found to be 8671.5 q in a year By incorporating the demand of the bioresources, it was also observed that bioresources produced in the village is surplus.It was found that energy demand of the village comes to be 101367.8 kWh. The surplus bioenergy resource of the village had a energy generation capacity upto the 727539.82 kWh. The ratio of bioresources availability to demand represent the bioresources status and it was found 7:1. It clearly indicates that bioresources in the village was surplus. It was realized that, renewable energy generation system, based on gasification and biogas suited to the village bioresources which have no ecological impact on cycle of bioresources. The total power generator size of proposed renewable energy system was found to be 50 kW for village Nimbhora.
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