Technical Feasibility of Photovoltaic Fuel Cell: A Model of Green Home Power Supply for Rural India
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International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 Technical Feasibility of Photovoltaic Fuel Cell: A Model of Green Home Power Supply for Rural India S.N.Singh1, Preeta John2, Navneet Prabhakar3 1 National Institute of Technology Jamshedpur, India 2 NTTF Jamshedpur, India 3 National Institute of Technology Jamshedpur, India results in almost no CO2 emission, which will help in Abstract: In this paper a hybrid solar PV fuel cell (PVFC) reducing the rate of global warming . In order to power generating system employing PV module, Battery for adopt such system for rural environment, the technical storage , PEM electrolyser for hydrogen generation, PEM feasibility study of such PVFC system need to be carried FC for DC electricity generation, and PCU(inverter) for out with model parameters available in manufacturer’s DC-AC converter purpose have been designed and modeled performance data sheets or measurements obtained from for conversion of DC power obtainable from renewable energy sorces to AC power for indian rural house. The literature. hydrogen fuel cell serves as the primary power source and In this research work, design model and control strategy the photo-voltaic cell acts as the secondary power source. If of an autonomous PVFC system has been developed and the household load is greater than the power produced by simulation test has been performed to validate the the primary source i.e fuel cell then both PV and FC act system for supply of power to rural house in remote together to manage the load. The stimulation has been done area where grid is not available. The PV as a standalone using MATLAB/ SIMULINK. Load sensitivity analysis has may produces electricity to meet the energy been conducted with varying load as well as insolation and requirement of home load . But during low radiation the results were found consistant. period, the system require to be integrated with fuel Keyword : PVFC, Solar Cell, PEM Fuel Cell, DC-AC cell & supplement the load power requirement at user converter, PEM Electrolyser etc. end. PV cell charges the battery and charges are fed to electolyser which in turn fed to fuel cell for producing 1. INTRODUCTION electricity. A schematic diagram of the system is shown in Fig.1. The fuel cell acts as primary source and the Electricity is the basic need of a human being. The PV cell acts as secondary power supply. demand of electricity is increasing day by day. On the other hand the generating capacity of grid power station is falling due to shoratage of raw materials such as fossil fuel (Natural gas, petroleum, etc.). Also the products on their combustion are causing global problems like greenhouse effect and pollution which are greatest threats to our environment today. Renewable energy sources (Solar, wind, FC, etc.) are a few alternative energy sources. Among all solar PV sources is gaining popularity due to production of pollution free green electricity from freely available solar radiation, available in every corner of country throughout the season. However due to large variation in solar radiation during sun hour and large sizing of PV cell, the PV system needs to be integrated with other sources such as battery or fuel cell to make it cost effective. The fuel cell power Figure 1: Schematic Diagram of Photo-voltaic Fuel cell supply is very attractive option to be used in an (PVFC) hybrid system integrated system along with the PV cell, because the 2. FUEL CELL fuel cell power system has many attractive features such as efficiency, fast load-response, modular production The Fuel cell (FC) is an electrochemical device that and fuel flexibility. The fast response of the fuel cell can produces direct current electricity through the reaction of solve the photovoltaic’s inherent problem of intermittent hydrogen and oxygen in the presence of an electrolyte. power generation. Moreover, their high efficiency They are an attractive option for use with intermittent Volume 1, Issue 2 July-August 2012 Page 216 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 sources of generation, like the PV, because of high dT= difference between Tcell and Tstc efficiency, fast load response, modularity, and fuel Ci = current temperature coefficient (1/deg.C) flexibility. Unlike a battery, a FC does not require = 6e-3/Pstc* Vmpp recharging. Their feasibility in coordination with PV Cv = voltage temperature coefficient (1/deg.C) systems can be demonstrated successfully for both grid- = -73e-3/Vmpp connected or grid deprived a standalone applications. Other advantages of FC are the re-usability of exhaust The value of STC (Standard Test Conditions) Power per heat, on-site installation, and diversity of fuels. The fuel unit of area is 76.3W/m2. The value of K (thermal for the FC can be hydrogen or any other hydrogen- resistance) has been determined to be 0.021 from 5 sec containing compound, which on reprocessing can produce average value of irradiance over a year. The calculations hydrogen. The use of electrolysis to produce hydrogen have been carried out on the basis of the standard from water is an efficient method from very small to very photovoltaic module with the parameters shown in the large scales. Additionally, when PV is used with the Table. 1 for Solyndra SL-001-150(150 W). electrolyzer, it is the cleanest source of hydrogen with no pollutants produced. On the small scale, a PV array Table 1 : Electrical Characteristics coupled to an electrolyzer and H2 storage tank provides a Sl. Parameter(s) Specifications flexible system, which could be installed in any location 1 Rated Power Pmpp 150 Wp in rural India with little maintenance. A single PEM fuel cell produces a limited voltage, usually less than 1V. In 2 Rated Voltage Vmpp 65.7 V order to produce a useful voltage for practical 3 Rated Current Impp 2.28 A applications, several cells are connected in series to form 4 Open Circuit Voltage Voc 91.4 V a fuel cell stack. The output voltage depends on the 5 Short Circuit Current Isc 2.72 A 6 Temp. Coefficient of Power - 0.38%/˚C number of the cells in the stack. The PEM electrolyzer 7 Temp. Coefficient of Voltage -0.265 V/˚C and PEM fuel cell can work in reverse action mode of 8 Series Fuse Rating 23 A operation. A Proton Exchange Membrane (PEM) electrolyser 3. MODELLING Fig.2(a) is used in order to get H2 gas from water . In a photovoltaic cell operating in the clamped voltage The temperature of water should be in the range 80- region, the output voltage of the module is fixed at the 100˚C. The energy required is 500Wh/Nm3 of H2. operating voltage of the system which is equal to the battery voltage (+12 V in this case). The global reactions taking place at the electrodes are: Assuming the module temperature is linearly dependent Anode : 6H2O(l) => O2(g) + 4H3O+(l) + 4e- on the ambient temperature and power. Cathode : 4H3O+(l) + 4e- => 4H2(g)+ 4H2O(l) Tcell =Tamb+ K.G (1) The cell half reactions are: Where, Anode : H2 => 2H+ + 2e- Tcell : Cell temperature Cathode : ½ O2 + 2H+ + 2e- => H2O Tamb : Ambient temperature The overall reaction: H2 + ½ O2 => H2O G : Irradiance W/m2 K : Equivalent thermal resistance The parametric equation for calculating the module Power  is expressed as : Pmod = Pstc *((Grel+ L)/ (Grel+ O))*N*Grel (2) Where, Grel = G/Gref Gref = 1000 W/m2 L= 0.001267789 O = 0.025403774 N = (1+O)/ (1+L) MPP Power corrected by temperature coefficient is given in equation (3) Pmpp,corrected = Pmod(1+ Ci.dT)(1+Cv.dT) (3) Figure 2: (a) A PEM electrolyser (b) PEM Fuel Cell Where, Volume 1, Issue 2 July-August 2012 Page 217 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 Table 2 : PEM Electrolyser Sl. Parameter(s) Specification 5. POWER CONDITIONING UNITS (PCUS) 1 Type PEM 2 Temperature of Operation 80-100˚C Photovoltaic or Fuel Cell power systems, which generate 3 Pressure of Operation 1-70 bars power as a direct current (DC), require power conversion 4 Electric consumption 500Wh units to convert the power from DC to alternating current 5 Energy efficiency 80-90% (AC). This power could be connected to the transmission 6 Life duration 1,50,000 hours and distribution network of a utility grid or grid deprived stand alone rural grid. There are other applications, The obtained H2 is fed to the PEM Fuel cell Fig.2(b) where it is necessary to be able to control power flow in which gives the output to the DC-AC inverter for further both directions between the AC and DC sides. For all supply to other circuits. The ratings of the PEM hydrogen these cases power conditioning units are used. Power fuel cells are given as  the specification is reflected in conditioning units (PCUs) are defined generally as a Table 3. Table 3 : PEM Fuel Cell rating module that transforms DC power to AC power Sl Parameter(s) Specifications (inverters). Here in this study a power converter of 12 volt . has been proposed which convert 12 volt DC supply to 1 Fuel cell current rating at 48V 10 A 220 volt 50 Hz approximated sine wave power supply. 2 Fuel cell power rating at 48 V 480 W The THD value of such PSU is very low in the order of 3 Fuel utilization factor 0.9 10% or even low. 4. POWER MANAGEMENT STRATEGY 6. SIMULATION AND RESULTS In the schematic diagram of the PVFC Solar hybrid The mathematical models of the PVFC Solar hybrid system as shown in Fig.1, the Photo-voltaic cell acts as system described above have been simulated in MATLAB the secondary power source. The main motive of the PV 7(2009) version. The simulation consists of the cell is providing power to the electrolyser for electrolysis temperature variation and its effect on photovoltaic and production of hydrogen. The Fuel Cell acts as the module to generate power output of the photovoltaic cell primary power source and is capable to meet the entire during sun hour period (Fig.4). The energy produced by power needs of a small rural house . The power PV cell is stored in Battery. The output power of the PV provided by the FC is fed to the DC-AC inverter which system, however, fluctuates specially during cloudy converts the DC power to the required AC power to meet weather depending on solar insulation and surface the home load . In case of overload, shortage of Temperature. The use of holography film on solar plate power or failure of fuel cell due to any reason, then the may increase the efficiency of these solar plates. PV cell provides an emergency backup system. The secondary battery stores power when the PV cell is not providing energy to the electrolyser for electrolysis i.e. when there is sufficient inventory of hydrogen available. The power flow diagram given below shows the operation of the PVFC integrated system (Fig. 3) Then a storage system must be used to deliver the required power at lower insulation levels and during the night. The panel surface temperature varies between 20 and 45C during the year. Figure 5: SOC of Battery Figure 3: Power Flow diagram of the PVFC Solar hybrid power system Volume 1, Issue 2 July-August 2012 Page 218 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 The photovoltaic module stops supplying power to the solar PV devices, various antipollution apparatus can be primary battery when the battery is fully charged or the operated such as water purification through electro H2 storage is full and starts supplying power to the chemical processing and stopping desert expansion by PV secondary battery. The critical state of charge water pumping with tree plantation. However, control (SOC_critical) is taken as 40% of SOC. Fig. 5 shows the problems arise due to large variances of PV output power percentage time for which the SOC is higher than 40%. under different insulation levels. To overcome this This shows the optimal design of PV as well as battery problem, PV power plants integrated with one such FC sizing for average load under consideration 480 Wh. system has been proposed in this research study The It is seen that the photovoltaic cell provides enough power PVFC technology is very promising for delivering clean for the PEM electrolyser to operate during summer and efficient power for applications in rural areas. With months but during winter time the power provided by the increased pollution and greenhouse gas emission PV cell reduces and the primary battery is charged slowly concerns, PVFC serves the needs as an eco-friendly hence the production of H2 is hampered and so is the technology with no carbon emission. The fuel cell power supply to the output. So for the winter months, it is provides the PVFC system compactness, it has no moving suggested that either we use more number of solar panels parts which lead to no combustion in ideal conditions, or the supply to the electrolyser has to be discontinuous and thus the system can achieve 99.99% reliability. Fuel for some period of time allowing the primary battery to cells and Photovoltaic cells when used alone are quiet charge. During that period the emergency load can be inefficient, but when both are integrated they not only carried out by the secondary battery. The operation of PV reduce the cost but also become more efficient. This cell is independent of the load and only depends on the technology is very useful power source in remote availability of irradiance. The load profile of fuel cell is locations where electricity is not available. The PVFC shown in Fig 6&7. systems have a wide range of application in the rural areas such as home power supply, pumping sets used in farms, charging laptops and cellular phones etc. The power supply may find its application in petrol pump in remote area. The rural telephone exchange can be powered from this system. Literacy programme can be conducted in adult education centres during evening hours. Village market can be powered through this source of supply even in late hours of night. 8. CONCLUSION The simulations and results show that the PVFC Solar Figure 6: Load Profile of Fuel Cell in Summer hybrid system is capable of performing well in meeting the external load using the energy produced by the system. The power supplied by the Fuel Cell is DC which is converted to AC by the inverter as the power required by the household appliances is AC signal. The PVFC system is economically feasible as the production of power is dependent on two sources and the life time expectancy of both the sources is relatively higher as compared to conventional power sources. This system is easy to install, easily available and relatively easier to handle. Thus we can say that the PVFC Solar hybrid system should serve as a reliable viable power source in Figure 7: Load Profile of Fuel Cell in Winter rural areas. 7. APPLICATION OF PVFC SYSTEM REFERENCES Renewable energy sources (solar, wind, etc) are  T.Veziroglu, “Hydrogen Energy System: A Permanent attracting more attention as alternative energy sources to Solution to Global Problems”, Clean Energy Research Institute, USA, 2004. http://www.iahe.org/hydrogen energy conventional fossil fuel energy sources. This is not only system.htm due to the diminishing fuel sources, but also due to  D.Mayer, R.Metkemeijer, S. Busquet, P.Caselitz, J.Bard, environmental pollution and global warming problems. and et al, Photovoltaic/Electrolyser/fuel cell hybrid system Among these sources is the solar energy, which is the the Tomorrow Power Station for Remote Areas, 17th most promising, as the fabrication of less costly PV EPVSEC, Munich Germany, pp.2529-2530, 2001. devices becomes a reality. With increased penetration of Volume 1, Issue 2 July-August 2012 Page 219 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856  D.S. Kim, A.M. Gabor, V. Yelundur, A.D. Upadhyaya, V. Meemongkolkiat, A. Rohatgi. "String ribbon silicon solar cells with 17.8% efficiency". Proceedings of 3rd World Conference on Photovoltaic Energy Conversion, pp1293– 1296, 2003.  A.R.Balkin, “Modelling A 500W Polymer Electrolyzer Membrane Fuel Cell”, Bs.D, University of Technology, Facaulty of Engineering, Sydney, 2002.  F.Barbir, T.Gomez, “Efficiency and Economics of Proton Exchange Membrane (PEM) Fuel Cells”, Int. J. Hydrogen Energy, Vol.22, No.10/11, pp.1027-1037, 1997.  G.Hoogers, Fuel Cell Technology handbook, CRC Press LLC, 2003.  ASME 8th International Fuel Cell Science, Engineering & Technology Conference, 2010.  S.Busquet, R.Metkemeyer and D.Mayer: “Development of a Clean Stand-alone Power System Integrating PV, Fuel Cell and Electrolyser”, Proc. Of the Photovoltaic Hybrid Power Systems Conference, Aix en Provence, 2000.  J.Benz, B.Ortiz, W.Roth, and et al, “Fuel Cells in Photovoltaic Hybrid Systems for Stand-Alone Power Suplies”, 2nd European PV-Hybrid and Mini-Grid Conference, Kassel, Germany, pp. 1- 4, 2003. AUTHORS Dr S.N. Singh had completed doctoral PhD degree at the Department of Electrical Engineering, National Institute of Technology Jamshedpur (India). He obtained his B.Tech degree in Electronics and communication engineering from BIT Mesra (A Deemed university), Ranchi - Jharkhand (India) in 1979/80. Presently his area of interest is solar energy conversion technology. He had published more than 50 papers in National and International journals based on his research work. He had remained Head of Department of Electronics and Communication Engineering for two terms and presently heading Govt. of India sponsored VLSI SMDP-II Project. Preeta John graduated in Electrical Engineering from T.K.M College of Engineering, (Kerala University) Kollam, Kerala - India and post-graduated in Power Electronics from National Institute of Technology Calicut, Kerala - India. Her areas of interest are soft switched DC-DC and DC-AC converters and Renewable energy sources. She is currently heading the Electronic department at NTTF at R D Tata Technical Education Centre, Jamshedpur. Navneet Prabhakar is pursuing B.Tech (Hons) in Electronics and Communication Engineering from National Institute of Technology, Jamshedpur (India). His area of interest is non conventional energy sources and their development. He has completed several projects on VLSI based control system . Volume 1, Issue 2 July-August 2012 Page 220