Economic Feasibility Analysis ofelectrical Hybrid Grid in a City Area

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1 Economic Feasibility Analysis ofelectrical Hybrid Grid in a City Area M. S Islam, Member IEEE A. Islam, Member IEEE Abstract Bangladesh is a developing country which has been suffering from severe electricity crisis due to shortage of efficient technical plan, less trained personnel, mismanagement of distribution & poor infrastructure. The objective of this paper is to develop a logistic type numerical optimum model of hybrid grid, taking into consideration of renewable and conventional fossil resources of Bangladesh.The Hybrid Optimization Model of Renewable Energy (HOMER) simulation software was used to conduct a cost benefit analysis for the proposed model. Simulation model was used to find out the best technically feasible renewable energy, which is cost effective for various households in a city area. The impact on the environment due to conventional fossil fuel generation was analyzed for the proposed model. Sensitivity analysis was carried out with diesel price and wind speed to get optimum result for the proposed hybrid grid. Implementation of this model in Bangladesh can show a potential way to produce electricity at less cost to mitigate the huge demand of the customer. Index Terms-Hybrid Grid,HOMER, Renewable Energy,Economic Feasibility, LVRT, Fossil Fuel, Smart Grid. R I. INTRODUCTION enewable energy is considered as the high potential source of energy. Use of renewable energy resources bears the utmost importance due to the depletion of oil and other non-renewable resources,production of environmental unfriendly substances by fossil fuel combustion.renewable energy s such as PV/Wind/Battery,hybrid photovoltaic/wind/battery are gradually seeking enormous importance to provide costeffective alternatives for generating electricity in remote regions in many developing countries. With the implementation of smart grid technologies there has been tremendous push to develop architecture that enables proper integration of renewable resources and also provide better controls to support applications like Low Voltage Ride Through (LVRT). Net zero and renewable energy sources offsets fossil fuel power plants thus reducing carbon footprint and avoiding further damages due to global warming. This has positive effect on reducing CO2 emission. It is a pertinent fact that global warming is expected to change terrain and climate of many countries unless effective measures have taken immediately [4]. In the light of December 1997 Kyoto s protocol on climate change (due to carbon dioxide emission), about 160 nations have reached a first ever agreement to start using the Renewable/Wind/PV power to limit carbon dioxide emission to almost zero. Even though Photovoltaic (PV) is an abundant source of power and recently the PV equipment costs has come down dramatically; the cost is still very high The authors are with Electrical Engineering Department, Florida International University (FIU), FL33174 ( misla004@fiu.edu ). in comparison to the fossil fuel sources. Older data shows that a PV on an average capital cost is about $ 4000 /kw, capital cost of conventional power s is about $1000/kW[10]. The high initial investment cost of PV s possess the main road-block especially for developing countries like Bangladesh that obviously resist promotion of this technology at massive-scale. PV installations have gained much support for power generation in remote areas where utility grid is unable to reach or is cost in effective.for supplying stable, uninterrupted and sustainable supply to the consumer, currently a lot of program has been accelerated by the government, utility companies and researchers to enhance robustness of the existing grid and to find alternative resources of energy. Economically feasible and commercially viable large number of installations are still far away in future for stand-alone non -grid tied power sources. Component cost and gain in the performance, attention towards renewable energy alternatives sources for electric power generation in stand-alone applications is gaining great attention day by day. Wind and solar energy are key sources amongst the various types of renewable sources. Hybrid brings multiple key advantages such as peak load shaving and un-interrupted power flow if the has optimal energy storage capability. Recently fuel cell and electrolyzer technology have given an option for using hydrogen as an energy storage medium effectively[11]. A hybrid energy based on such alternative technologies operating in parallel with renewable sources can become a convenient part of the small or large scale power generation infrastructure.the performance of a hybrid energy is highly dependent on the environmental conditions (i.e location),and analysis is required to investigate the overall cost, component size and cost economy. The latitude and longitude of Bangladesh is and degrees North and and degrees East respectively[6,14], which indicate excellent possibility of solar energy utilization. Daily solar radiation varies between 4 and 6.5 kwh/m2. A densely populated tropical country like Bangladesh could be electrified by PV grid using the inexhaustible and pollution free solar energy without using any novel technologies[ 2 ]. In this paper, an economic feasibility study has been carried out for Hybrid grid in the overpopulated City Dhaka, Bangladesh. Study of the hybrid, the meteorological data of Solar Radiation, hourly wind speed has taken for Dhaka, Bangladesh (Longitude 90 59' East and Latitude 23 59' (North) from NASA Surface meteorology and Solar Energy [2,12]. Various combinations of PV array, Conventional Grid, diesel generator, wind turbine, fuel cell (FC) were taken into account to get optimum economic /13/$ IEEE

2 solution that would meet a given load in some residential houses in Dhaka [13] which is pictorially shown here as a 24 hrs load profile. Collaborating with Renewable primary sources (wind and solar), more conventional fossil fuel (diesel generator ) based was considered. Moreover, conventional grid power source has also been added for cost benefit analysis. Other renewable sources such as, microhydro, geothermal, biomass, etc. are not feasible in the city of Dhaka due to some other unavoidable reasons. 2. HOMER SOFTWARE : HybridOptimization Model for Electric Renewable (HOMER) is an exclusive software basically used for comparative economic analyses on a hybrid power s which is developed by NREL, Colorado, USA. HOMER is a design model that determines the optimal architecture and control strategy of the hybrid energy. User Input to HOMER will perform an hourly simulation of desired combination of user s choice of Hybrid model and it ranks the according to user-chosen criteria, such as cost of energy (COE) or capital costs of the. Moreover, HOMER can perform Sensitivity Analyses [1,8] using certain parameters (e.g. Fuel cost/unit, Diesel price /unit, Grid energy price / unit, slope of fuel consumption in fuel cell, marginal fuel consumption etc ). Bangladesh is an ideal location for utilization of solar energy since solar radiation varies between kwh/m2 in the whole year due to geographical location. Table 1: Solar Radiation and Clearness Index of the City. Month Daily Solar Radiation (kwh/m 2 ) Clearness Index Jan Feb March April May June July Aug Sep Oct Nov Dec SYSTEM DESCRIPTION: 3.1 LOAD FOR THE PROPOSED DESIGN : Proposed hybrid power is optimized & sensitized to ensure the utility of some households load with an average AC energy consumption of 67 kwh/d and peak load of 6.9 kw with an average 2.78 kw( Assumed baseline & Scaled data are same in HOMER). Peak load at Dhaka city normally in the Month of April & May and around 6 :00 PM daily in the whole year due to using bulk amount of supply for lighting, heater etc [13]. Figure 1 shows the daily load profile. Figure 2 : Monthly solar radiation with clearness index 3.3 WIND TURBINE: Figure 1 : Load profile on hourly basis in a day. 3.2 PV ENERGY RESOURCES: NASA Surface Meteorology and Solar Energy (SSE) data set is used for analysis.to synthesize data by HOMER [1], it needs to enter twelve average monthly values of either solar radiation or clearness index. After entering the values in the table, HOMER builds a set of 8760 solar radiation values. It creates the synthesized values using the Graham Algorithm (GA).Table1 shows the solar radiation Baseline data for Dhaka city by NASA SSE. Figure 2 shows monthly solar radiation with clearness index. Bergy wind power turbine [5] used for simulation of hybrid s. Model of the turbine BWC XL1, 1kW DC output. In this simulation 1 kw wind turbine capital cost $ 8995 has considered [5],Replacement cost $7000, Operational and Maintenance (O&M) cost $ 200/yr. The lifetime was considered 25 yrs and Hub height considered 25 m. The sizes of wind turbine evaluated were 0, 1, 4, 5, 10, 15, 20, 25 kw for optimization process. Monthly wind speed data for the city [2]is collected from Bangladesh Meteorological Department (BMD) as shown in Figure 3.Scaled annual average velocity 3.72 m/s.anemometer height 25m considered in the design & altitude of the city 4m.

3 4) SIMULATED HYBRID SYSTEM ANALYSIS IN HOMER PV-FUEL CELL-BATTERY-CONVERTER HYBRID SYSTEM Figure 3 : Monthly wind speed (m/s). 3.4 DIESEL FUEL PRICE $1/L was considered for diesel price for the all four simulated model for diesel generator (DG). 3.5 ECONOMICS & CONSTRAINTS Project lifetime considered to be 25 years.the annual real interest rate was taken as 5%. For the proposed fixed capital cost $40,000, fixed O&M cost was considered $500 for all four hybrid topology. 3.6 PHOTOVOLTAIC PANELS The installation cost of PV array typically [9] 2857 $/kw which used in the present study. The replacement cost was taken as 2200 $/kw. Operational and Maintenance (O&M) cost for photovoltaic array is considered $180/yr and its lifetime is 25 years. A derating factor of 80% was applied to the electric production from each panel & no tracking was assumed. 3.7 DC TO AC INVERTERS Figure 4 : Hybrid design layout of PV-FC-Battery- Figure 4 shows the schematic diagram of this model. PV array of 20 kw was used which net present cost (NPC) $ 57,140, O & M cost $ 50,738 [3].160 Trojan batteries used which Capital cost was $53,600, Replacement cost $ 39,632, O & M cost $1,409 as shown in figure 5. For storing Hydrogen for fuel cell Hydrogen tank used with 15 kg. H2 storage tank cost $214 typically [3]. Electrolyzer used which Capital cost $4000/kW, Replacement cost $ 3000, O & M cost $ 200/yr typically. The typical value of the inverter recently is $4286 for 6kW. Cost used in the current work $ 6286 for 8kW as capital cost, Replacement cost $6000, Operational and Maintenance (O&M) cost was considered $100/yr. 3.8 DIESEL GENERATORS Capital cost for a commercially available diesel generator[3] for $1400 for 4kW generation. In this simulation for DG, $1880 for capital cost has considered for 4kW generation,replacement cost $1590,Operational and Maintenance (O&M) cost $0.015/hr BATTERY BANK For study Trojan battery [7] was considered. Battery model is L16P.L16P battery has nominal capacity 360 Ah (Max capacity 391Ah & maximum charging current 18A. Round trip efficiency 85%, initial State of Charge (SOC) was considered 50%). For 10 Trojan batteries capital cost was considered $3350, Operation & Maintenance cost $100/yr & Replacement cost $2800 considered for the project lifetime.battery string numbers were considered 0, 10, 20, 40, 60, 100, 150, 200 in search space in HOMER to store excess electricity and saving of peak generation. Figure 5 : Cash flow summary of PV-Fuel Cell-Battery- hybrid. From the simulated output of cash flow summary & optimization( in figures 5 & 6), it is clear that total NPC cost is $ 251,922, Levelized COE is $ 0.788/kWh, Operating cost $ 6,718/yr. Whereas emission for all toxic gases are zero due to unavailability of fossil fuel sources. Total excess electricity 6.58% (1950 kwh/yr),capacity shortage 8.19 %,Total AC primary load 22,680 kwh/yr. Figure 6 : PV-FC Battery- hybrid optimized result

4 4.1.2 PV- WIND TURBINE - DG - GRID - CONVERTER HYBRID SYSTEM Fig. 7 shows the schematic diagram of this model. For this model simulated result for optimization is shown in figure 8. PV array of 10 kw was used which cost $28,570, O & M cost $ 25, Trojan batteries which capital cost $ 26,800,Replacement cost $19,816, O & M cost $ kW DC Bergy wind turbine [5] (BWC XL1)used which capital cost $ 8,995, O & M cost $ 2,819 used in the. Total O & M cost for project lifetime is $38,865. Lifetime was considered 25 yrs for hub height 25m. AC was used of 8 KW which capital cost $ 6286, O & M cost $1409. Figure 9 : Individual component cash flow summary of PV- WT DG-Grid - hybrid PV- DIESEL GENERATOR WIND TURBINE - BATTERY CONVERTER HYBRID SYSTEM. Figure 10 shows the schematic diagram of this model. For this model simulated result for optimization is shown in figure 11.PV array of 10 kw was used which cost $ 28,570, O & M cost $ 25, Trojan Batteries were considered which capital cost $ 26,800,Replacement cost $ 19,816, O & M cost $ kw diesel generator used which capital cost $ 1,880,O & M cost $ 886 which calculated as a linear scale. AC Inverter was used of 8 kw which capital cost $ 6286, O & M cost $1409. Figure 7 : PV-WT DG-Grid - hybrid From the simulation result in figure 8,total net present cost (NPC) was $226,467, Operating cost $ 8,084 /yr and levelized Cost of Energy(COE) was $0.663 /kwh. Monthly average electricity production (56% from PV, 4% from wind turbine, 41% from diesel generator). Excess energy production kwh/yr(~ 0%). Renewable fraction Figure 9 shows individual component cash flow summary of the hybrid. Figure10 : PV-DieselGenerator -WT-Battery- hybrid Figure 8 : Optimization result of PV-WT DG-Grid converter hybrid Figure 11 : Optimization result for PV Diesel Generator WT-Battery- hybrid. From the simulation result it was seen that Net Present Cost ( NPC )was $ 226,542, operating cost $ 8,089/yr and levelized cost of energy was $ 0.664/kWh. The monthly average electric production. (56% from PV, 4% from Wind Turbine,41% from Diesel Generator ). Excess energy production 21.4 kwh/yr (0.08 %).

5 4.1.4 DIESEL GENERATOR- WIND TURBINE - BATTERY - CONVERTER HYBRID SYSTEM Fig. 12 shows the schematic diagram of this model. For this model simulated result for optimization is shown in figure 13.1 kw wind turbine was used which cost $ 8995, O & M cost $ 2, Trojan Batteries were used which capital cost $ 26,800,Replacement cost $ 19,816, O & M cost $ kw diesel generator used which capital cost $ 1,880, O & M cost $ 1,769. AC Inverter was used of 8 kw which capital cost $ 6286,Replacement cost 2,261, O & M cost $ 1,409. results are shown in Figure 14.It was seen that the Operating Cost, total NPC and the Cost of Energy (COE) have increased due to rise in fuel consumption of DG from 0.3 to 0.40 L/hr/kW (at the same wind speed ). An Optimal System Type (OST) has displayed as a function of different sensitivity parameters shown in figure 15. Figure 12 : Diesel Generator -WT-Battery- hybrid Figure 14 : Sensitivity cases of changing two variables ( wind speed & DG FC Slope ) only It was seen from figure 14 that at scaled annual average wind speed (3.72 m/s) diesel fuel slope changes from 0.3 to 0.40 L/hr/kW whereas superimposed levelized cost of energy also changes from $ to $ From the simulation result in figure 13, it was seen that Net Present Cost( NPC ) was $ 237,177.Operating cost $ 10,871/yr and levelized Cost of Energy was $ 0.705/kWh. The monthly average electricity production. (4% from PV, 96% from Diesel Generator ). Excess energy production 33.8 kwh/yr (0.14 %). Figure 15 : Optimal type with total NPC superimposed Figure 13 : Optimization cost result for Diesel Generator - WT-Battery- hybrid. 5. SENSITIVITY ANALYSIS BY HOMER : From figure 15 it was seen that total NPC was changing from $212,038 to $ 225,621 only in where Wind/PV/battery had the same NPC irrespective of DG FC Slope (L/hr/kW). For Low FC slope PV/DG is the most preferred for the city. Sensitivity study further carried on the most economically feasible PV-WT-DG-Grid - hybrid only. Two sensitivity variables were considered : wind speed variation & diesel generator slope of fuel consumption. A total of 15 sensitivity cases (wind speed (3-cases), DG FC slope (5-cases)) were simulated with PV-WT DG-Grid- hybrid with good result. The optimization

6 6. COMPARATIVE ANALYSIS OF DIFFERENT HYBRID SYSTEMS From the summary table 2, it is clear that according to cost effectiveness PV-WT-DG-Grid -Battery- is the best optimized (lowest NPC, acceptable range Operating Cost-OC, Lowest Cost of Energy-COE ) and technically viable preferred hybrid grid for the city. From table 3 it is depicted that the pollutant emissions (i.e a lot of toxic gases) in this preferred is less than other s. Table 2 : Cost summary of different configuration. System Configuration Type PV-FuelCell-Battery PV- WT - DG - GRID- hybrid WT - DG -Battery - hybrid PV- WT - DG - hybrid NPC in $ Operating Cost of Cost (OC) in $/yr Energy (COE) in $/kwh 251,922 6, ,467 8, ,177 10, Table 3 : Emissions produced from different configuration. Pollutant due to emissions PV- WT - DG - GRID - hybrid kg/yr 226,542 8, WT - DG - Battery - hybrid kg/yr PV- WT - DG - hybrid kg/yr Carbon dioxide 9,276 19,251 9,289 Carbon monoxide Unburned hydrocarbons Particulate matter Sulfur dioxide Nitrogen oxides CONCLUSION Using HOMER software, the hybrid grid configurations and their applicability were analyzed taking into account of the cost effectiveness of the process and minimization of the emission of the environmental hazard. The necessary equipment for the process has been considered optimistically for the desired load, further detailed economic analysis is required for implementation of the proposed grid with hardware. Moreover, rules, regulations and interconnection charge for conventional grid should be studied prior to combining proposed hybrid grid with conventional fossil fuel technology It is a pertinent fact that cost of energy produced by fossil fuels is gradually increasing due to increasing price of fuel and diminishing resources. So, renewable energy sources with the conventional power grid combination have attracted significant attention from the researchers worldwide to mitigate the vast demand of energy in the world. Further research is envisioned that will support the investigation of the electric power crisis in North American and other geographical regions on the basis of the method defined in this paper. [1] Homer Energy website REFERENCES [2] Bangladesh Meteorological Department, Monthly wind speed data, Climate Division- Bangladesh. [3] Maximum Retail price list Rahimafrooz Distribution Ltd and Excell Power Bangladesh. [4] Ali S. Global progress in renewable energy In: Proceedings of abstracts, 7th Arab international solar energy conference, Sharjah, U.A.E., February p. 4. [5] Bergy website [6] Statistical Year Book 2010, Bangladesh Bureau of Statistics. [7] Trojan Battery website - [8] Givler T, Lilienthal P. Using HOMER_ Software, NREL s micropower optimization model, to explore the role of gen-sets in small solar power s technical report NREL/TP-710e36774; May [9] M. Moniruzzaman, Samiul Hasan Cost analysis of PV /Wind/Diesel/ Grid connected Hybrid Systems International Conference on Informatics, Electronics & Vision, [10] Hansen U. Technological options for power generation. The Energy Journal 1998;19(2): [11] Swaminathan S, Sen, R. K (2000) Electric utility applications of hydrogen energy. [12] NASA Surface meteorology and Solar Energy, A renewable energy resource web site [13] Annual Report,Bangladesh Power Development Board (BPDB). [14] Sharmeen Farhana and Md. Mafizur Rahman Characterizing rainfall trend in Bangladesh by temporal statistics analysis 4th Annual Paper Meet and 1st Civil Engineering Congress, December 22-24, 2011, Dhaka, Bangladesh.