Renewable Energy Integrated Microgrid for Rural ...

Renewable Energy Integrated Microgrid for Rural Electrification and Productive use

Renewable Energy Integrated Microgrid for Muhammad Taheruzzaman Rural Electrification and Productive use BTU-Brandenburg Technical University Cottbus

Muhammad Taheruzzaman [email protected] BTU-Brandenburg Technical University Cottbus [email protected]

Abstract. Electric power crisis is one of the major problems in developing countries, and Bangladesh is one of them. The breach between demand and supply is increasing disturbingly. Yet 52 % of the total population has no access to electricity in Bangladesh, and 75 % of them are the rural and isolated community. This paper addresses the renewable energy integrated small-scale power system for rural electrification in the developing countries like Bangladesh. This paper also concentrates on optimal design, sizing, and planning of distributed generation sources. Investigating the optimum design and sizing of generation unit for reliable and cost effective operation of microgrid; four different configurations including only biomass generator, biomass, PV/wind mix system, and further planning the main grid can also connect take into account. Lastly, technical and economic feasibility and optimization compared for both standalone and grid connected system for the community based electrification. Keywords: DC Microgrid (DC-MG), solar home system (SHS), renewable energy, rural electrification.

1

Introduction

The global energy system trends have been struggling against global warming petrifyingly since surface temperature is also rising, the transition of energy system transform to a fully sustainable based local renewable sources would be a great solution to protect the environment. To increase about 124 % of renewable energy and 209% of biofuel by 2020, cut off half of greenhouse gasses by 2050 [1]. At present, 1.2 billion of total global population, which means around 20 % of total population have no access to electricity, South Asian countries accounts for 37% of the world's population without access to electricity [2]. The gap between demand and supply is increasing petrifyingly, due to high population growth in Bangladesh, the demand of electrical power increases and number of people are living in energy poverty, despite a continued positive efforts experienced for electrification across all over the Bangladesh [3]. Approximately less than 60 % of the overall population in the

c M. Kr´ ○ atk´ y, J. Dvorsk´ y, P. Moravec (Eds.): WOFEX 2016, pp. 549–556. ˇ – Technical University of Ostrava, FEECS, 2016, ISBN 978-80-248-3961-5. VSB

adfa, p. 1, 2011.

550

Muhammad Taheruzzaman

developing countries have access to electricity, whereas urban electrification 80 % and about 15-25 % of rural areas are electrified. support rural electrification efforts by the respective country governments including use of renewable energy technologies including PV, wind, and biomass. Despite the continuous efforts of the international community and governments throughout the world, the pace of rural electrification in many developing countries is still very slow [4]. Rural electrification typically poses more challenges than urban electrification in terms of policy, finance, and institutional setup because of its distinct features. While the initial solution for rural electrification can be spreading the main grid by extending the transmission line, but some instance not technically and economically possible [5]. It is commonly agreed that to meet the present demand is the burden for natural gas and other conventional fossil fuels, integration of local renewable sources such as solar PV, small wind turbine (SWT), and biomass would be the alternate source of energy. Furthermore, the isolated and remote areas, RES distributed sources are being significantly recognized as costeffective sources [6]. The remote areas, higher transmission line losses, and higher cost of transmission lines are encouraging to use of distributed renewable energy. With declining the cost of PV and increasing the performance of small wind turbine (SWT), in addition to improvement of the technologies including control system, and storage system, standalone renewable integrated system significantly enhances its stride [7]. Due to geographical location country like Bangladesh is blessed to generates PV and wind energy based electricity, unremitting deterioration of the prices and soft loan arrangement by state owned organization Infrastructure and Development Company Limited (IDCOL) of Bangladesh already installed 3.2 million solar home system (SHS) by 2014 and extent the number of 6 million by 2017 through installing 50,000 SHS each month [8].

2

System Description

The community based µ-grid consisting of small scale biomass-fueled generator, distributed micro generation unit including PV system, and small wind turbine (SWT). The distributed micro generation sources are being well popular in the developing eventually in the isolated community from the utility network. For enhancing rural electrification and access to electricity µ-grid would be the best possible solution. The concept of community based µ -grid which acknowledges integrating distributed µ-generator sources to the low voltage (LV) distributed network [9]. The proposed system where PV system is considered as several solar home systems (SHSs) connected to the system as distributed µ-generation sources and defined as prosumers1, SWT and biomass fueled generator shows in fig.1 . The choice of generator is driven by the need and local conditions at the target to end user, keeping in mind that the system integration should have a good balance of being most efficient, reliable, cost-effective, socially beneficial, least polluting and sustainable in 1 Solar home system (SHS) integrated microgrid; where SHS act as feed electricity into the microgrid and consumer electricity as well

Renewable Energy Integrated Microgrid. . .

551

the long run. In developing countries hybrid renewable integrated system have a particular strong relevance in improving the quality of life, especially among rural communities. The electric load in the system considered in DC, including households’ appliances, irrigation pumps, rice husking machine, cold storage refrigeration system. The biomass-fueled generator is the primary main source of energy and SHS and wind turbine used for an additional source for electricity to meet the base load of the system, and utilize the use of cost free fuels.

Fig. 1. Proposed Community based DC-MG

3

Model Assumption and Input

3.1

Electric Load

The fig.1, representation of a hypothetical load profile of a community in Bangladesh. The proposed system, the community households consumed 70 kWh per day with maximum peak 15 kW at the evening. The demand data is synthetic and 5% day to day variation considered, and Homer tool randomly inducements the daily perturbation factor in the very hour. Bangladesh is a tropical country as winter demand is comparatively lower than the other seasons. 3.2

Productive Usable Load

The productive load considered as Irrigation pump operates between 7:00 to 11:00 each day from October to March. A small size community based cold storage working for 24 hours a day with the capacity of .8 kW and a rice husking mills peak load 1.3 kW and operates 8 hours a day except the weekend. Total consumption including households and productive loads 36,885 kWh per year. 3.3

Local Renewable Potential

The solar irritation profile of kaptai, Chittagong (26°26´ N, 96°16´ E) assume for this work. Solar radiation data is taken from the NASA surface metrology and solar

552


energy2. The proposed location monthly average solar radiation 4.63 kWh/m2/day. The monthly average wind energy 5.79 m/s respectively. Biomass combustion has 68-79 % efficiency depending on fuel moisture content, and combustor design, and combustion operation [10]. The community food waste, crops, leafs, and animal manure to generate biogas that landfill avoided which reduces methane potential damage the atmosphere [11]. The local cows and buffalos roughly produced 10 kg/day, and approximately 60 % of Agricultural residues, 30 % of animal waste and poultry and 10 % of others average biomass production. The average biomass production = 2.04 tons/day. 3.4

Community Based Battery Storage System

The proposed system where comply the meet the load and supply, a community based battery storage is recommended. As the distribution system defined as 12 V, the battery nominal voltage 12 V has considered as the terminal voltage. The nominal capacity of each battery assumes 1 kWh, and maximum capacity 80 Ah. Initial state of charge 100% and minimum charge 40% considered for the system optimization.

4

Result and Comparison of various cases

In this section, four difference cases according to system configurations for analyze all assumptions and constrains for the favorable optimal design option for MG planning as shows in table 1. The first case assumes as an isolated network system fed by a biomass generator. However, the system capital investment is very high installation, operation and maintenance cost, though the fuel cost not so expensive as compare to other traditional fossil fuel such as diesel or furnace oil system. In case-2 the system configures along with number of SHS, SWT, and biomass fueled generator, while case-1 only biomass dependent system, and case-3 is also mixed fuel based configuration but number of SHS increases from 20 to 25 (i.e. PV system capacity increases to 2.5 kW). The case-3 configuration mainly instigates from bottom up swarm electrification concept, where the surplus electricity can be supply to the new users without interrupting present participants. Finally, case-4 assumes similar to case-3 but operates grid connected mode, and the MG system operation adopt to purchase electricity from the grid and sell back surplus unit to the grid. Designing and planning of optimal MG system for rural electrification different configuration taking into account. The main objectives of these interpretation finding the least-cost, self-dependent system, effective use of biomass and other renewable sources for renewable contribution.

2 HOMER Analysis https://analysis.nrel.gov/homer/.


553

Table 1: Summary of different configurations for optimal studies

Cases case-1 case-2 case-3 case-4

Description of various scheme Biomass fueled generator Renewable mixed: Biomass generator, SWT, SHSs renewable mixed: increase capacity of PV Grid Connected with DC-MG: allow purchase and sellback

The first configuration (case-1) consists of only a 15 kW biomass generator which operates 6423 hours and produces 38,791 kWh per year. The produced electricity is not only meeting the total demand of community loads including households but also productive use, and 139 kWh of excess electricity produces. The precise design can be optimized with 12 battery integrate within the system. While case-2, renewable mixed system cogitates along with 10 kW biomass generator, 2.0 kW PV (i.e. 20 SHS), 2 SWT (turbine capacity 1 kW each). The mixed fuel system all together produces 38,440 kWh per year, alone biomass generator produces 31,000 kWh by operates 4852 hours every year, aside the 20 SHSs and 2 SWT produces 3,197 kWh, and 4,274 kWh respectively. The total production of electricity for case-2 shows in fig. 2(a), and the PV system and SWT operates roughly 4400 hours and 4700 hours respectively per year for each case.

Fig. 2. Electricity Production in MG (a) case-2 and (b) case-3

The renewable mixed fuel MG in case-3 configures along 10 kW biomass generator, 2.5 kW PV system (25 SHS system), and 2 kW SWT, where the biomass generator operates 4791 hours and generates 31,657 kWh, and SWT produces same as previous configuration 4,274 kWh per year. As the number of SHS has considered in case-3, production increases to 3,990 kWh. In case-3 total production 39,921, kWh per year by the renewable mixed fuel system, the biomass, wind energy, and PV contributes 78%, 9%, and 13% individually shows in figure 2(b). In case-4 consisting also of 2.5 kW PV (25 SHSs), 2 SWT, and capacity of biomass generator similar as the previous cases 10kW. Among all together these sources produce 51,148 kWh per year; while 6.5 % by PV, 8.5% by SWT, 72% by the generator, and 13% from grid purchase shows in fig. 3(2), and the system surplus electricity can be selling back to the grid shows in fig.3(b). The case wise comparison among various cases precisely present in table 2, biomass generator fuel consumptions and operational hours for different cases present in table 3.

554


Fig. 3. Case - 4 (a) electricity Production (b) Average monthly grid purchase and sell back

The case-3 and case-4 are the most economical possible solution for optimal configuration. However, among all the configurations holds over 85% of renewable penetration, case-4 (grid extension cost of capital not considered) is one of the cheapest as the NPC, Levelized cost of economic (LCOE), and operating costs are comparatively lower than any other cases of the configuration shown in table 4. However, the LCOE is higher in case-1 and case-2 because of large capital cost. It has shown case-1 is grip the largest cost components. Table 2: Optimal configuration of various cases Component Biomass generator [kWh/year] PV system SWT Grid Total electricity

Case-1 38,791 0 0

Case-2 31,000 3,197 4274

0 38,791

0

Case-3 31,657 3990 4274 0

Case-4 36,879 3,197 4,274 6,798

38,440

39,931

51,148

100

100

86

Renewable fraction [%]

100

Excess electricity (kWh/year)

139

0

1789

0

Number of battery

12

10

8

5

Table 3: Case-wise comparison of biomass generator Biomass generator Case-1 Case-2

Case-3

Case-4

Number of operation hours [hour]

6423

4852

4791

3726

Fuel consumption [tons/year]

22.4

17.6

29.89

17.62

Table 4: Comparison of cost constrains for various cases Economic Constrains Case-1 Case-2

Case-3

Case-4

Net Present value [$]

106,303

103,235

91,737

63,377

LCOE [$/kWh]

0.203

0.113

0.113

0.091

Operating cost [$/year]

7,364

8,394

4,551

2,731


5

555

Conclusion

An acceptable amount of power generation in a sustainable way is an important issue for rapidly increasing population and economic development in the low-income and developing countries. Renewable energy can play an effective role to meet energy demand. Since it is an agrarian country, biomass is one of the potential renewable energy sources in Bangladesh. Agricultural crop residues, residual waste, woods, and animal manure are the major sources of biomass energy in the remote areas country. In this paper has determined the potential of biomass that operates various ranges of generator fueled by the available local biomass, focuses the optimal design and compare different feasible configuration that complies the local biomass potential. The studies also determine the opportunism of other sources including solar PV and wind energy, and the renewable integrated system would be the ultimate solution for the electricity access into the rural community. The investigation also focuses the break-even point of grid connected system, technical and economic feasibility of the proposed standalone DC-MG configuration care case -2 and case-3. If grid connected is available, then (case-4) is the most economically promising solution. In addition, SHS also illustrate in this paper which also one of the emerging technology in Bangladesh. The social context in Bangladesh stimulate house-owns SHSs, the excess electricity can be stored in the community based battery storage, and shares among other end-users. The SSHs are the prosumers, end users and productive loads are consumers in the DC-MG system. It is to be noted renewable mix more need to study as a consequence of higher investment costs and replacement costs. The government of Bangladesh may introduce the feed-in tariffs to encourage more renewable penetration for present and future electricity demand, and significant role in the renewable integration. Finally, 10 kW biomass-fueled generator, 20 SHS, and 2 SWT is the optimal solution for the 50 households and other community based productive usable load. .

References 1. T. Boden, G. Marland and R. Andres, "Global, Regional, and National Fossil-Fuel CO2 Emissions. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory,," U.S. Department of Energy, , Oak Ridge, Tenn., U.S.A, 2010. 2. D. Palit, "Solar energy programs for rural electrification: Experiences and lessons," Elsvier: Energy for sustaiable development , no. 17, p. 270–279 , 2013. 3. IEA, "World Energy Outlook 2013," International Energy Aagency, 2013. [Online]. Available: http://dx.doi.org/10.1787/weo-2013-en. [Accessed 12 March 2016]. 4. C. Paul, "Infrastructure, rural electrification and development.," Energy for Development , no. 15, pp. 304-312, 2011. 5. M. Fadaee; M. Radzi, "Multi-objective optimization of a stand-alone hybrid renewable energy system by using evolutionary algorithms: a review," in Renewable Sustainable Energy Rev, 16, 2012. 6. H. Omar and B. Kankar, "Optimal planning and design of a renewable energy based supply system for microgrids," Renewable enrgy , vol. 45, pp. 7-15 , 2012 .

556


7. IRENA (International Renewable Energy Agency), "International off-grid renewable energy conference: key findings and recommendations," 2013. [Online]. Available: www.irena.org/DocumentDownloads/Publications/IOREC_Key%20Findings%20and%20Recommend ations.pdf. 8. R. Kempener, O. Lavagne d’Ortigue, D. Saygin; et. al., "Off grid Renewable Energy System: Status and Methodological Status," IRENA (International Renewable Energy Agency), Bonn, Germany , 2015 9. D. Pudjianto. G. Strbac; et.al., "Investigation of Regulatory Commercial, Economic and Environmental issues in microgrids," International conference on future power systems, 2005. 10. D. Hall and R. Overend, "Biomass Combustion," in Biomass regenerable Energy, Jhon Wiley and sons Ltd., 1987, pp. 2003-219. 11. Cogenco, " Dalika combined heat and power," [Online]. Available: http://www.cogenco.com/ukcogenco/ressources/documents/1/44419,Cannington-Cold-Stores_Cogenco.pdf. [Accessed 01 Feb 2016].