Rural electrification of a remote island by renewable energy sources

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Renewable Energy 32 (2007) 2491–2501 www.elsevier.com/locate/renene

Rural electrification of a remote island by renewable energy sources S.K. Singala,, Varunb, R.P. Singha a

Alternate Hydro Energy Centre, Indian Institute of Technology, Roorkee, India b MIT, Mooradabad, UP, India Received 9 September 2006; accepted 31 December 2006 Available online 6 March 2007

Abstract India has a large number of remote small villages and islands that lack in the electricity, and probability of connecting them with the high voltage gridlines in the near future is very poor due to financial and technical constraints. The main electrical load in these villages is domestic. In this paper a study has been presented for sustainable development of renewable energy sources to fulfill the energy demands of a remote island having a cluster of five villages. The total potential of electricity from these resources is estimated to be equivalent to 3530 kWh/day whereas demand is only 2310 kWh/day with an installed capacity of 450 kW, which is sufficient to replace the existing power generation system dominated by diesel operated system. r 2007 Elsevier Ltd. All rights reserved. Keywords: Bio gas energy; Renewable energy; Solar photo voltaic; Sustainable development; Wind energy

1. Introduction Increasing demand of energy and negative impacts of fossil fuels on the environment has emphasized the need of harnessing energy from renewable sources. These sources can create a significant impact in the generation of grid electricity, as we see from the progress made in wind power, small hydro, biomass power and bagasse cogeneration in the last few years. The per capita consumption of electricity in India during the year 2004–2005 was 606-kWh/yr [1]. The Ministry of power, government of India has set on objective of Corresponding author. Tel.: +91 1332 285167(O), 273273(R); fax: +91 1332 273517, 273560.

E-mail addresses: [email protected], [email protected] (S.K. Singal). 0960-1481/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2006.12.013

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providing ‘‘Power for all by the year 2012’’. This will entail electrification of all villages by 2007 and of all households by 2012. The infrastructure would need the availability of assured and reliable power at affordable price through reliable and adequate generation, transmission and distribution facilities [2,3]. The present installed generating capacity of the country is about 124,280 MW in which the share of renewable energy accounts for 4.9% with 6190 MW only. The energy shortage is about 8.35% where as peak demand shortage is 12.5%. The energy deficit can be met by renewable energy sources as India has a high solar energy potential with the daily average of solar radiation intensity on horizontal surface approximately 1000 W/m2 and annual sunshine days about 300. A remote rural island, which represents a considerable number of villages, has been selected for implementing a techno-economic study using renewable energy sources such as biogas, biomass gasification and solar photovoltaic systems for electrification of such villages. 2. The study area: Neil Island Andaman and Nicobar is a group of islands in India. Neil Island was found to be one of the most appropriate islands subjected to electrification by renewable energy sources. Neil Island is situated in South Eastern region of the Bay of Bengal, midway between peninsular India and Myanmar and located between 61450 and 131410 North latitudes and 921120 and 931570 East longitude. It is situated in Andaman group of islands under Port Blair tehsil. Port Blair is the capital of Andaman and Nicobar Island. The island has an area of 18.9 km, and it comprises of five villages namely Bharatpur, Laxmanpur, Ramnagar, Sitapur and Neil Kendra. The location of island under study is shown in Fig. 1 and the location of all the villages is shown in Fig. 2. 3. Existing energy scenario at Neil Island In order to workout the characteristic features of the rural energy scene, the door to door survey was carried out covering all the households in all the five villages at Neil Island. The data were collected for getting different inputs such as number of family members, type of house/building, land holding, irrigation facilities, average monthly income, energy consumption, electricity requirement and water availability, etc. Table 1 shows the population and households at Neil Island. The peak electricity demand occurs during evening hours, i.e. from 5:30 pm to 11:30 pm, when the whole population is at home after days work and almost comprises of lighting loads. Table 2 presents the energy consumption in cooking. 3.1. Present electricity consumption All the five villages at the island are electrified through the electricity generated by the existing 400 kW diesel generating plant and 50 kW solar power plant (total installed capacity 450 kW). It is revealed from the survey that out of total 581 households of the island 472 (81%) are electrified and remaining 109 (19%) do not have electricity connection. There is 550 kW connected load out of which 1681 incandescent bulbs constitute 18.4% of total load, 348 water pumps used for irrigation constitute 25.3%, industrial and other load constitute 20.8%, 339 televisions constitute 12.3% and 835 fans constitute 9.3% of total load. Table 3 shows the details of connected load.

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Fig. 1. Location map of Neil Island.

4. Availability of renewable energy sources at Neil Island A detailed study has been carried out to estimate potential of available renewable energy sources at Neil Island. 4.1. Bio gas energy The biomass is available in the form of cattle dung and bird dung, which can be converted into biogas. On analysis of survey details, it was found that there are 1180 cattle


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Fig. 2. Village location map of Neil Island. Table 1 Population and households at Neil Island S. No

Name of village

Population

No. of households

Land holding (Acres)

1. 2. 3. 4. 5.

Bharatpur Laxmanpur Ramnagar Sitapur Neil Kendra

605 396 650 294 861

107 68 131 50 225

186.56 160.96 244.00 116.05 147.25

2806

581

854.82

Total

Table 2 Energy consumption in cooking Sl. No.

Name of village

Chulha (Convention.)

Chulhaa (improved)

Gas stove

Kerosene stove

Kerosene lantern

Kerosene lamp

Total (nos.)

1 2 3 4 5

Bharatpur Laxmanpur Ramnagar Sitapur Neil Kendra

122 70 142 50 157

1 0 2 1 0

9 3 7 2 68

25 22 74 18 98

13 6 11 1 10

258 201 396 171 407

428 302 632 243 740

Total (nos.)

541

4

89

237

41

1433

2345

a

Chulha-local stove.

and 3633 birds’ population at Neil Island. The biogas production from the dung has been worked out based on the assumption that 7 kg dung will be available from each cow/ox, 10 kg from buffalo, 1 kg from goat and 0.5 kg/day from hen/duck. Whereas 12 kg of dung


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Table 3 Details of connected load at Neil Island Name of Village

Bharatpur

Laxmanpur

Ramnagar

Sitapur

Devices

No. Load (kW)

No.

No.

No.

Load No. (kW)

Bulb (incandescent) Bulb(CFL) Tube light (40 W) Fan Television Radio/music system VCR/VCP/CD player Computer Refrigerator Washing machine Mixie/grinder Irrigation pump Industrial/other load Street light Total Average /household Per capita

284 14 87 137 39 33 23 0 1 0 3 68

221 2 36 108 42 25 27 0 3 0 2 45

166 9 69 93 40 32 26 0 1 0 3 45

617 12 293 327 133 79 43 2 22 2 31 70

17.04 0.14 3.48 8.22 7.8 0.825 1.15 0 0.3 0 1.2 27.2 26.5 15 0.6 704 94.455 8.69 1.17 1.41 0.19

Load (kW)

13.26 0.02 1.44 6.48 8.4 0.625 1.35 0 0.9 0 0.8 18 10 11 0.44 522 61.715 9.16 1.08 1.50 0.18

393 1 154 190 85 86 53 0 10 0 8 120

Load (kW)

23.58 0.01 6.16 11.4 17 2.15 2.65 0 3 0 3.2 48 30 20 0.8 1120 147.95 10.98 1.45 2.13 0.28

9.96 0.09 2.76 5.58 8 0.8 1.3 0 0.3 0 1.2 18 0 15 0.6 499 48.59 11.60 1.13 1.95 0.19

Neil Kendra Load (kW)

37.02 0.12 11.72 19.62 26.6 1.975 2.15 0.3 6.6 1 12.4 28 48 35 1.4 1666 196.905 8.81 1.04 2.31 0.27

Total No.

Load (kW)

1681 38 639 855 339 255 172 2 37 2 47 348 0 96 4511 9.56 1.92

100.86 0.38 25.56 51.3 67.8 6.375 8.6 0.3 11.1 1 18.8 139.2 114.5 3.84 549.615 1.16 0.23

produces 1 m3 of biogas with calorific value of biogas is 4700–6000 kcal/m3 [4]. The village wise details of dung availability and energy potential are shown in Table 4. 4.1.1. System sizing for anaerobic digestion As 1 kWh ¼ 860 kcal, the electricity generation from the available biogas will be 2977 kWh and the net electrical energy generation per day will be 980 kWh assuming 33% efficiency. This is sufficient to run a diesel generating (DG) set of capacity 100 kW for 8 h. A biogas operated compression ignition engine generator set of 100 kW rating shall be required to generate electric power. The engine is to be operated in dual fuel mode with diesel substitution up to 70%. 4.1.2. Cost estimation 4.1.2.1. Capital cost. The cost of a biogas plant of 60 m3 capacity has been taken as Indian Rs. 3,02,500/plant as per prevailing market rates, which also includes the cost of the diesel generating set [5]. The cost function as reproduced below is used for computing the cost. Plant cost ¼ 3; 02; 500 N B , where NB ¼ number of biogas plant of capacity 60 m3. Thus, the total plant cost of biogas system of 100 kW with accessories and civil works is worked out to be Rs. 30,25,000. 4.1.2.2. Cost of energy. Since the diesel generating set works in duel fuel mode replacing 70% diesel with biogas, the cost of fuel is calculated on the basis of the cost of diesel and


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Table 4 Cattle dung availability and energy potential estimation S. No

Name of village

Animal dung available/ day (kg)

Bird dung available/ day (kg)

Total dung available/ day (kg)

Net dung collected to convert into biogas/ day (75% collection efficiency)

Total biogas production/ day (cu-m)

Total energy/day (kcal 106)

1. 2. 3. 4. 5.

Bharatpur Laxmanpur Ramnagar Sitapur Neil Kendra Total

997 1378 2064 1385 1059

427 245 552 285 308

1424 1623 2616 1670 1367

1068 1217 1962 1253 1025

89 101 164 104 85

0.42 0.48 0.77 0.49 0.40

6883

1817

8700

6525

544

2.56

6.

the cost of dung. Taking the specific fuel consumption of diesel generating set in diesel mode as 0.3 L/kWh, the diesel consumption in duel mode will be 0.09 L/kWh and the cost of dung will be Rs. 1.25/kWh. Therefore, the cost of fuel will be Rs.4.25/kWh (taking diesel cost Rs. 33.25/L as prevailing in the area). Expression used for calculating the unit cost of energy (COE) is [5] O&M ½302500 N B PRF þ ½annual generation unit cost of fuel 100 þ 100 , COE ¼ total annual energy generation ðkWhÞ where, NB ¼ no. of plants, PRF ¼ annual plant recovery factor, O & M ¼ annual operation and maintenance cost. With plant recovery factor as 15% and operation and maintenance cost as 2% of capital cost, the cost of energy from biogas plant comes out to be Rs.6.39/kWh. 4.2. Biomass gasification Based on the survey conducted, the quality and quantity of agricultural wastes available annually in the area has been estimated. The agro wastes available in the area are crop residue (rice straw), rice husk, biomass waste (coconut shell, etc.). The crop residue mainly rice straw is used by the villages to feed their cattle. The details of potential of various agro wastes available for use in the gasifier are given in Table 5. 4.2.1. System sizing for biomass gasification Since, 1 kWh ¼ 860 kcal, the electricity generation from the biomass will be 6233 kWh. Taking overall system efficiency as 33%, the net electrical energy generation per day is 2057 kWh. The availability of biomass is suitable to run a 150 kW DG set for 16 h a day. The down draft type gasifier will be required to convert the biomass into producer gas. 4.2.2. Cost estimation 4.2.2.1. Plant cost. According to the available correlation, the plant cost has been calculated. The base cost factor is calculated by modifying it in present context on the basis


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Table 5 Annual potential of agro-waste and biomass energy at Neil Island Sl.No.

Type of biomass

Biomass collected per year (kg)

Biomass used per year (kg)

Biomass available for use in gasifier per year (kg)

Total biomass energy potential per year for power generation (in kcal 106)

1. 2. 3.

Crop residue (rice straw) Rice husk Biomass waste (coconut shell, etc.) Biomass waste from bark and lops and tops on forest extraction from forest department (kg) Total

226,790 54,690 144,489

132,240 0 0

94,550 54,690 144,489

236 164 506

330,000

30,000

300,000

1050

755,969

162,240

593,729

1956

4.

5.

Note: The calorific value of rice straw, rice husk, coconut shell and wood are 2500, 3000, 3500 and 3500, respectively.

of the prevailing market prices as available from the manufacturers [4]. Plant costðin Rs:Þ ¼ 4:73 104 ðkWÞ0:85 . 4.2.2.2. Cost of energy. Since the diesel generating set works in duel fuel mode replacing 70% diesel with producer gas, the cost of fuel is calculated on the basis of the cost of diesel and the cost of feed stocks. Taking the specific fuel consumption of diesel generating set in diesel mode as 0.3 L/kWh, the diesel consumption in duel fuel mode will be 0.09 L/kWh and the cost of feed stocks Rs. 1.25/kwh. Therefore, cost of fuel will be Rs.4.25/kWh. The unit cost of energy is calculated by using the following expression [5]: O&M 4:73 104 ðkWÞ0:85 PRF þ ½unit cost of fuel annual generation 100 þ 100 COE ¼ , annual generation where, kW is installed capacity of the plant. With plant recovery factor as 15%, operation and maintenance cost as 2% of capital cost, the cost of energy from gasifier plant comes out to be Rs.5.04/kWh. 4.3. Solar photo voltaic power generation At solar noon on a clear March or September day, the solar radiation at the equator is about 1000 W/m2. The typical solar panel today achieves between 10% and 15% conversion. The maximum electrical efficiency of a silicon cell is about 21%. Using a costlier technology, 31% conversion has been achieved. Thus assuming 13% efficiency, the solar cell having 1 m2 of surface area in full sunlight at solar noon at equator during March or September would produce approximately 130 W of peak power. Most panels, for a


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variety of design reasons, contain 32—36 individual cells. One cell has the size of 400 400 , thus the total area of a panel having 32 cells comes out to 0.32 m2. A 100 kWp solar power plant needs 1800 panels of 70 W each. The total area comes out to be 576 m2 and total unit generated 75 kWh/h. Assuming peak hours as 4.2/day, the total unit generation per day for 100 kWp solar power plant would be 315 kWh with silicon cell efficiency of 13% and standard power density of 1000 W/m2. 4.3.1. System sizing of SPV 4.3.1.1. Array size and total number of modules. The array load and array size can be calculated, based on average solar insolation of 4.2 103 Wh/m2/day and number of peak hours as 4.2 h, assuming mismatch factor of 0.85, battery efficiency as 0.8 and charge regulator efficiency as 0.9. The capacity and the size of the array are calculated using the following equations: total daily loadðkWh=dayÞ battery efficiency charge regulator efficiency 500 ¼ 700. ¼ 0:8 0:9

Array load ¼

array loadðkWh=dayÞ no: of peak hours mismatch factor 700 ¼ ¼ 200 kWp=day: 4:2 0:85

Array size ¼

Thus, the array, capable of delivering 200 kWp, shall be required. Choosing standard modules of 70 Wp each with V–I characteristics having peak current 4.15 A and short-circuit current of 4.48 A. Peak hour of 17.43 Ah/day for average solar insolations of 4.2 103 Wh/m2/day, mismatch or derate factor of 0.85, battery efficiency as 0.8, charge regulator efficiency as 0.9, module nominal voltage is 12 V, and the system nominal voltage is 220 V. no: minal system voltage ðV Þ no: minal module voltage ðvÞ 220 ¼ 18:3 say 18 nos. ¼ 12

No: of series modules ¼

daily load demandðWhÞ module daily outputðWhÞ daily loadðAhÞ ¼ battery charging efficiency module derating 500000=220 ¼ 0:8 0:85 17:43 ¼ 200 ðaproxÞ.

No: of parallel modules ¼

Total numbers of modules ¼ 18 s 200p. The total number of series and parallel module ¼ 3600.


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4.3.1.2. Sizing of battery. The battery capacities are selected based upon the standard ratings of batteries available in the market. We have considered tubular type and low maintenance batteries. The capacity is decided assuming 5 days as reserve, maximum allowable depth of discharge (DOD) as 80% and temperature derating of 0.85. The battery capacity has been calculated using the following equations: Battery capacity ¼

daily loadðAhÞ reserve days ; max allowable depth of dischargeðDODÞ temperature derate rate factor

1047 Ah ð24 h rateÞ ¼ 1:33 787 Ah ð8 h rateÞ ð500000=220Þ 5 ¼ 12565 Ah; ¼ 0:8 0:85 1:33

Rate factor ¼

no: of days of autonomy 24 h=day maximum percentage usable 5 24 ¼ 150h, ¼ 0:8

Average rate of discharge ðhÞ ¼

nominal system voltageðV Þ nominal battery voltageðvÞ 220 ¼ 18:3 say 18, ¼ 12

No: of series batteries ¼

capacity of battery bank indivisual battery capacity 12565 ¼ ¼ 64; 200 Total numbers of batteries ¼ 18 64 ¼ 1152 of 200 Ah each. The details of batteries and modules required for 200 kWp solar power plants to generate about 500 kWh/day are shown in Table 6. No: of parallel batteries ¼

4.3.2. Cost estimation The cost factor for solar panel depends upon the peak watt to be catered to the utility. Using the state-of-the art technology, the cost is about Rs. 165/Wp presently, although, it may shoot up to Rs. 3500/Wp for space application. NASA Lewis Research Centre has analyzed the cost /peak Watt and found the balance of system (BOS) cost of the installation as follows [5]: BOS cost ¼ 296 35 ðkW 1000Þ0:412 in Rs:=W: Therefore, the total cost of PV system is equal to the cost of solar cell panel plus BOS cost. The BOS cost is inversely proportional to the PV array size; the PV capital cost may be calculated as follows: PV capital cost ðRs:Þ ¼ ½165 þ 296 35ðkW 1000Þ0:412 kW 1000 PV capital cost ¼ ½165 þ 296 35ð200 1000Þ0:412 200 1000 ¼ Rs:4; 65; 63; 300= .

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Table 6 Modules and battery details S. No

Description

Numbers

1

Batteries

Series Parallel Total

18 64 1152

2

Modules

Series Parallel Total

18 200 3600

Ministry of non-conventional energy sources (MNES), Govt. of India [2] provides the subsidy for grid connected solar power plant, which is 2/3rd of the project cost subject to a maximum of Rs.20 millions/100 kW. In this case an amount of Rs.3,10,42,200/- will be provided, as subsidy and the actual amount required for installation of 200-kWp solar power plants will be Rs. 1,55,21,100/- only: O&M ½capital cost PRF 100 þ 100 . Cost of energy ðCOEÞ ¼ total annual generation With plant recovery factor as 15% and operation and maintenance cost as 2% of the capital cost, the cost of energy from solar power plant comes out to be Rs. 17.60/kWh. 4.4. Other renewable energy sources Based on the survey conducted and earlier studies [6,7], it is found that the development of other renewable energy sources such as small hydropower, wind energy, ocean thermal energy, tidal energy and geothermal energy are impractical on this island hence not discussed. 5. Cost analysis of diesel power generation system The present cost of diesel generator is Rs. 20000 /kW including the cost of auxiliaries and civil works. Assuming specific fuel consumption of 0.3 L/kWh and rate of diesel as Rs.33.35/L, the unit fuel cost will be Rs.10/kWh. O&M þ ðannual generation unit cost of fuelÞ capital cost PRF 100 þ 100 COE ¼ . annual generation With capital cost as 20000 400 i.e. Rs. 80,00,000/-, plant recovery factor as 15% and operation and maintenance cost as 2% of capital cost, the cost of energy for diesel generator comes out to be Rs. 11.96/kWh. 6. Results and discussions The cost of electricity generation from diesel power plant comes out to be Rs 11.96 and there is very much scarcity of these conventional fuels. As the time passes the cost of these sources will become higher and there will be only option to shift our generation systems on


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renewable energy. The cost of generation of electricity from renewable energy sources comes out to be Rs. 6.39, 5.04 and 17.60/kWh for biogas, biomass gasification and solar PV system, respectively. Two of these resources are even cheaper than the conventional diesel generation system only solar system is costlier. If we take an average on the basis of the generation capacities than the cost comes out to be Rs. 10.92/kWh, which is also cheaper than the existing conventional diesel power plant. These renewable energy options do not create any adverse effect on the environment. One more benefit is that the generated units are more than the needed so there is a scope for the development of cottage industries. 7. Conclusions The demand of energy is growing owing to the development. Due to the problems associated with the development of conventional sources of energy, the focus is now shifted to renewable energies. India has potential of renewable energy source in abundance, which if developed properly can augment the growing demand of the energy. There is a need to make full use of renewable energy technologies to harness the untapped potential. In the present study, potential assessment of all the available renewable energy sources is carried out and found that the conventional diesel power plant can be replaced by renewable energy sources in self-sustainable manner to achieve energy independence in a remote island. It is suggested to replace existing 400 kW diesel generating plant and 50 kW solar power plant by 100 kW biogas power plant, 150 kW biomass gasification plant and 200 kW solar PV system. Such development will also ensure that there is no adverse impact on environment and socio-economic life of the habitants. References /http://www.powermin.nic.inS, Ministry of power, Govt. of India, 2006. /http://www.mnes.nic.inS, Ministry of non-conventional energy sources, Govt. of India, 2006. Annual report, 2004–2005. Ministry of non-conventional energy sources, Govt. of India, New Delhi. /www.indiasolar.com/cal-value.htmS. Das Prasahant Kumar, energy modeling for off grid electrification of cluster of villages, MTech dissertation, AHEC, IIT Roorkee, India, 2005. p. 90–2. [6] /http://www.and.nic.in/plan1/Electricity%20Dept.pdfS. [7] State development report for Andaman and Nicobar Island published by electricity department, Port Blair and available on website /http://www.and.nic.in/plan1/Electricity%20Dept.pdfS. [1] [2] [3] [4] [5]