Saad Dilshad

Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. International Journal of Modern Physics B Vol. 33 - (15 pages) c World Scientific Publishing Company DOI: 10.1142/S- A modeling approach for low-temperature SOFC-based micro-combined heat and power systems Fida Hussain∗ , M. Ashfaq Ahmad† , Saeed Badshah‡ , Rizwan Raza†,§ , M. Ajmal Khan†,¶ , Saleem Mumtazk , Saad Dilshad∗ , Raja Ali Riaz∗ , M. Jafar Hussain‡ and Ghazanfar Abbas†,∗∗ ∗Department of Electrical Engineering, COMSATS University Islamabad, Islamabad-44000, Pakistan †Department of Physics, COMSATS University Islamabad, Lahore Campus, Lahore-54000, Pakistan ‡Department of Mechanical Engineering, International Islamic University, Islamabad-44000, Pakistan §Department of Energy Technology, Royal Institute of Technology (KTH), 10044 Stockholm, Sweden ¶Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, P. R. China kInstitute of Chemical Sciences, Bahauddin Zakariya University, 60800 Multan, Pakistan ∗∗mian--Received 8 June 2018 Revised 1 November 2018 Accepted 5 November 2018 Published 12 February 2019 The world’s challenge is to determine a more efficient, economical and environmentalfriendly energy source to compete and replace the ongoing conventional energy resources. Solid oxide fuel cells (SOFCs) provide a highly efficient system to use divergent energy resources and have proved to provide the cleanest energy, least energy use, and lowest emissions. A techno-economic study is required to investigate the model design for SOFC-based micro-combined heat and power (m-CHP) systems for applications in terms of educational and commercial buildings. This work models and explores the optimized application of hydrogen gas-fueled SOFC-based m-CHP systems in educational buildings. Two educational departments’ loads are presented and model of SOFC-based m-CHP system against the different electric power demands is performed, in order to provide a techno-economic assessment of the technology. For successful development of the technology, results are related to system rightsizing, operating strategies, thermal to electric ratios, and match between end-use, with an aim towards classifying the overall feasibility and essential application requirements. Keywords: Energy systems model; fuel cells; low-temperature; micro-combined heat and power; solid oxide fuel cell. PACS number: 84.60.-h ∗∗ Corresponding author- F. Hussain et al. Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Nomenclature AC = Alternative Current CDC = Calcium-Doped Ceria CHP = Combined Heat and Power DEE = Department of Electrical Engineering DME = Department of Mechanical Engineering FC = Fuel Cell KW = Kilo Watt LT-SOFC = Low Temperature — Solid Oxide Fuel Cell m-CHP = micro-Combined Heat and Power mW = milli Watt Ni = Nickle NK-CDC = Sodium-Potassium Carbonated Calcium-Doped Ceria OCV = Open Circuit Voltage PEM = Proton Exchange Membrane PWh = Peta Watt hour rpm = round per minute SEM = Scanning Electron Microscopy TER = Thermal to Electric Ratio TWh = Tera Watt hour XRD = X-Ray Diffraction YSZ = Yttria Stabilized Zirconia 1. Introduction Due to the utilization of large amounts of fossil fuels, emissions of CO2 have formed serious worldwide environmental difficulties.1 Alternatively, the next generation will be required to identify new energy sources because with passage of time these fossil fuels are going out. In the past era, lots of efforts have been made by researchers to find out an alternative resource of energy to accomplish the demand of the coming generations.2 A fuel cell is an energy conversion entity converting a fuel (in gaseous form) into heat and electric power through electro-chemical combination of fuel with an oxidant (normally air). Solid Oxide fuel cell (SOFC) is one such technology that is the most efficient and environment-friendly technology for generation of electric power due to terrific tolerance to impurities and fuel flexibility.3–8 Fuel flexibility and diversity includes gaseous hydrocarbons like alkanes, dimethyl ether, fuels in liquid form like octane toluene, diesel and n-decane, vegetable oil, crude oil and jet fuel, and also solid fuels like activated carbon, biomass, and untreated coal.9–21 SOFC-based micro-combined heat and power (m-CHP) has been considered as one of the most favorable technologies to fulfill the heating and electrical demand of a building more efficiently. Regarding the emissions of CO2 , it has the potential to reduce it compared to energy consumption in the residential sector. Moreover, market size potential is large, and in total energy supply it could be significant to- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Modeling approach with experimental investigation for LTSOFC suggest this technology.22–24 Conventional work on SOFC is at high-temperature of-◦ C, where yttria-stabilized zirconia (YSZ) electrolyte is used to gain necessary high ionic conductivity. Because of this high operational temperature, SOFC faces hurdles in commercialization as it causes the thermal expansion mismatch, cell components degradation, and little choice of materials, etc.25–31 In order to use SOFC commercially, it is essential to decrease its operational temperature. By using conventional YSZ electrolyte and other conventional Ni-YSZ electrodes in a SOFC and then to make stack and module, correspondingly cell price will be high and power density will be low. Ultimately, by using this conventional cell in a model, the result seems to be not good in all aspects.32,33 Islamabad, the capital territory location of Pakistan, has been nominated (in this research) for consideration of an SOFC-based m-CHP system application. The annual temperature varies between 42◦ C and 9◦ C.34 The electricity consumption in the residential sector constitutes about 27% of the total world electricity consumption, amounting to 5.35 PWh.35 Therefore, for SOFCs, one potential application in Pakistan is the residential energy sector; with more than 66% of that energy usage been used in space heating, hot water demand, and space cooling purposes. Performance characteristics of the fuel cell system are mainly driven by design parameters of cell-stack, such as cell voltage, operating temperature, fuel utilization, and rise of cathode gas temperature. The techno-economic analysis importance is the ability to quantify advantages of operation of combined heat and power, and system design optimization. Adam et al. observed that m-CHP based on fuel cells provides savings in energy and cost, when it is used for buildings.36 According to Hawkes et al. an SOFC-based m-CHP system model has been presented to examine the techno-economic results of some cases for provision of residential demand of heat in the UK.37 They found that SOFC-based m-CHP is well-suited for gradual heating demand of space. According to Choudhury et al. the high temperature steam coming from SOFC can be further used to operate Rankine or Brayton cycle for more power generation, or for heating and cooling purposes (co-generation/tri-generation). Furthermore, they showed that SOFC-combined system efficiency (electrical plus thermal) can be reached to maximum of 90% depending on the operating condition and its configuration.38 In a recent study, natural gas SOFC-based m-CHP system unit of 84.2 kW for a university building was produced, and mathematical and conceptual design analysis are presented. They recommended in future work the study of thermal to electric ratios (TERs) for buildings.39 In another study, a natural gas SOFC-based m-CHP unit of 1 kW for residential purposes was produced, and presented the mathematical and conceptual design analysis. There results showed that the system of SOFC-based m-CHP designed here can deliver electric power of 1.01 kW and heating power of 0.52 kW.40 The novelty between literature and the model in this study is the operating temperature of SOFC, which is reduced from conventionally -◦ C) to comparatively low-temperature (550◦ C), and TERs are also taken in consideration. The lower operating temperature is a cost-effective approach- F. Hussain et al. Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. 2. Approach Different types of materials can be used to construct the electrodes of a fuel cell. Here in this research, BCFZ (Ba0.05 Cu0.25 Fe0.10 Zn0.60 ) oxide anode-based fuel cell has been used to estimate the final system. In this cell, Barium contributes to prevent corrosion; Copper is used for electron conducting behavior, Iron acts as a catalytic activity, and Zinc is a cheap material as compared to conventional Nickel. Two educational departments (total load demand for department of electrical engineering (DEE) is 50 kW and for department of mechanical engineering (DME) is 40 kW) of a university located at Islamabad, Pakistan have been considered for techno-economic modeling of SOFC-based m-CHP system. A main application parameter in this model system is the thermal to electric ratio (TER). TER may be based on space cooling, space heating, hot water demand, and its magnitude is greatly dependant on building type, location, usage patterns, design, time of day and year.40 Figure 1 shows variation between electrical, thermal and total efficiencies having load factor as a function of an SOFC-based system.37,42 2.1. Preparation of anode (Ba0.05 Cu0.25 Fe0.10 Zn0.60 ) Through dry method, using various compositions, BCFZ anode was successfully synthesized. The materials, namely Barium carbonate BaCO3 , Cupric carbonate hydroxide CuCO3 ·Cu (OH)2 , Iron nitrate nano-hydrate Fe(NO3 )2 · 9H2 O, and Zinc Nitrate Hexa-hydrate Zn(NO3 )2 · 6H2 O were bought from Sigma Aldrich (USA) and were held under process in order to construct anode materials. In order to form the homogeneous precursor, the stoichiometric fractions of these precursors were milled in a mortar through pestle. To sinter these precursors, they were located Fig. 1. (Color online) Efficiency versus load factor for SOFC system- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Modeling approach with experimental investigation for LTSOFC in a furnace. The temperature of the furnace was increased slowly up to 800◦ C and was held fixed for four h at this temperature, and then permitted to cool to roomtemperature. For 10 min, the sintered powders were further milled through addition of a little amount of carbon for providing porosity.43 2.2. Preparation of electrolyte NK-CDC Through co-precipitation method, Ce0.8 Ca0.2 O1.9 and Na2 CO3 : K2 CO3 (NKCDC) powder was prepared. To make calcium-doped ceria (CDC) powder, Ca(NO3 )2 · 4H2 O (Calcium Nitrate Tetra-hydrate) and Ce(NO3 )3 · 6H2 O (Cerium nitrate hexa-hydrate) bought from Sigma Aldrich (USA) were mixed into a 1000 ml of de-ionized water in 1:4 molar ratios under a forceful stirring process (800 rpm) at temperature 80◦ C. In order to coat a second stage on the CDC compound, Na2 CO3 (Sodium Carbonate) and K2 CO3 (Potassium Carbonate) were bought from Sigma Aldrich (USA). The powders were combined as molar ratio of 1:1 and mixed into 500 ml deionized water for 30 min under 1000 rpm at 100◦ C. The solution of both carbonates was poured dip-by-dip into CDC solution maintaining CDC: NK molar ratio as 1:2.5 and the stirring was carried with 1200 rpm at 150◦ C for extra two h. The pH value was known to be 9. Three times the precipitate was washed away with deionized water and vacuum filtration machine of glass was used to get NK-CDC agglomerate. At 100◦ C, this agglomerate was dried in an oven over night and at 700◦ C it was sintered in a digital furnace for four h. For homogeneity, this sintered powder was further ground in a mortar with a pestle.44 2.3. Preparation of cathode (Ba0.5 Sr0.5 Co0.2 Fe0.8 ) Through wet chemical method, the cathode material of BaCO3 (Barium carbonate), Sr(NO3 )2 (Strontium nitrate), CO(NO3 )2 · 6H2 O (Cobalt Nitrate Hexa-hydrate), and Fe(NO3 )3 ·9H2 O (Iron nitrate nano-hydrate) bought from Sigma Aldrich (USA) was synthesized in which different masses of metal nitrates were mixed in deionized water. As a precipitant agent, the oxalic acid was used. Through stirring at 100 rpm on hot plate, the agglomerate of BSCF compound was obtained. In open air, the agglomerate was dried. Further, at 800◦ C the material was sintered for four h.45,46 2.4. Anode-based SOFC cell To understand the involvement of porous anode, solid electrolyte and porous cathode materials, these materials were utilized to construct the SOFC. Solid electrolyte material was inserted in between two layers of porous anode and porous cathode. By using a hydraulic press, this adjustment of anode (BCFZ)/electrolyte (NKCDC)/cathode (BSCF) was then hard-pressed. The pressure of the hydraulic press was kept at 220 kg cm−2 . To test a single cell, a small pill having size of 13 mm diameter and 0.9 mm thickness was prepared. The active area was considered to be 0.64 cm2 , depending on the dimensions of testing holder. For 40 min, the hardpressed pill was sintered at temperature of 650◦ C. Before going to performance- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. F. Hussain et al. test, the silver paste was coated by brush on both surfaces of anode and cathode of the cell.46 Hydrogen was supplied at anode side and air was used at cathode side simultaneously. The results of the performance were measured at 550◦ C using LC-43, China fuel cell testing unit. In order to confirm the degradation factor of the cell, the single SOFC was tested in terms of its stability for 24 h continuously. 3. Results and Discussion 3.1. XRD analysis of used cell components The X-Ray diffractometery of our cell’s components like BCFZ (Ba0.05 Cu0.25 Fe0.10 Zn0.60 ) anode, NK-CDC (Ce0.8 Ca0.2 N0.025 K0.025 ) electrolyte, and BSCF (Ba0.5 Sr0.5 CO0.8 Fe0.2 ) cathode can be shown in Fig. 2.47 It has been observed from this figure that the BCFZ anode contains single phase structure that is emphasized during the sintering process, all the elements have completely shifted into Zn element. All the peaks were indexed and it has also been analyzed by JADE 5 software that the BCFZ has hexagonal structure. Statistics of all the peaks in XRD (X-Ray Diffraction) pattern of NK-CDC informs that the NK-CDC electrolyte retains a cubic fluorite structure.44 Calcium phase was not found in the pattern and it can be claimed that calcium has fully doped into ceria.44 Regarding the XRD analysis of BSCF cathode, it was reported that BSCF contains pervoskite structure.45 Particle sizes of each component BCFZ anode, NK-CDC electrolyte and BSCF cathode were also calculated using Scherer’s formula and noted to be 25, 12 and 48 nm, respectively, from the XRD data.43,44 In further findings it was reported that the anode of BCFZ is electrochemically compatible with electrolyte of NK-CDC. Both the materials, BCFZ anode Fig. 2. XRD patterns analysis of the fuel cell’s components- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Modeling approach with experimental investigation for LTSOFC Fig. 3. (Color online) Performance analysis of the single fuel cell in the temperature range of 400–550◦ C. Table 1. Performance of the single fuel cell (13 mm diameter) at temperature 550◦ C based on model developed. Fuel cell performance at 550◦ C Fuel cell components Composite anode Composite electrolyte Composite cathode Max. OCV (V) Max. C.D. (mA/cm2 ) Max P.D. (mW/cm2 ) BCFZ-NKCDC NKCDC BSCF-NKCDC 1.07 2328.12 933.41 and NK-CDC electrolyte, have single-phase structure and both ensure nano-size particles as showed by the X-Ray Diffraction (XRD) results. Asymmetrical fuel cell was experimentally tested with the combined construction of BCFZ anode material and BSCF cathode material, separated by a solid electrolyte of NK-CDC. The measurements were performed in the temperature limits of 400–550◦ C. The results of measurements can be shown in Fig. 3, and are demonstrated in Table 1.44 The maximum power density was achieved to be 933 mW/cm2 at the temperatures of 550◦ C, when hydrogen (H2 ) was provided as a fuel at anode side by the flow of 100 ml min−1 , and air as oxidant (O2 ) at cathode side. The value of OCV (open circuit voltage) was observed to be 1.07 over the same temperature of 550◦ C. In Fig. 3, the arrows indicate the axes. The small arrow pointed right represents current density versus voltage in the graph and the large arrow pointed left represents the current density versus power density in the graph. 3.2. System modeling Novelty between this model and literature is the SOFC stack and module operating temperature. Conventionally, SOFC-based systems are operated in temperature range of-◦ C,32,37,48 and the SOFC which is used in this study is operating at 550◦ C. This model was developed to fulfill the power demand of both- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. F. Hussain et al. Fig. 4. (Color online) Schematic model diagram for department of electrical engineering. departments, therefore, many cells are joined in series through interconnects that offer both electrical contacts and gas channels among individual cells. The resultant stacks are then organized in series and parallel configurations to deliver required voltage and power output. Estimation of power output with SOFCs from a single cell to a stack and then to a module, the schematic model diagram of power requirements according to various applications can be shown in Fig. 4. On the basis of established power density (∼ 933.4 mW/cm2 at 550◦ C) of the state-of-the-art SOFC, an 11 cm-by-11 cm planar cell corresponds to ∼ 113 W power output. In order to validate the maturity of single cell performance, the smaller values of voltage losses can be neglected because the cells stability was also checked and hence shown in Fig. 5. According to data, the module displays that a stack of 45 planar cells including interconnects (11 cm-by-11 cm-by-11 cm) can produce 5 kW, and thus corresponding module containing 10 stacks can produce 50 kW. Fig. 5. Single cell stability at 550◦ C- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Modeling approach with experimental investigation for LTSOFC Fig. 6. (Color online) Hydrogen fueled SOFC CHP system. Conceptual hydrogen-based SOFC system is shown in Fig. 6.48 Input parameters for the proposed model are shown in Table 2, while the calculated results including efficiency for the system have been listed in Table 3. System pressure of hydrogen fuel is enhanced at fuel compressor and preheated at fuel preheater. After that, H2 is entered to the SOFC stack module and distributed to anode part of each cell. Air is also pressurized and preheated before entrance to cathode part of each cell. A DC power is produced after electrochemical reaction and through inverter, Table 2. Input parameters for the system. Input parameter Value Air and fuel pressure Net power Cell voltage Pressure drop in heat exchangers Pressure drop in fuel cell Cell active area System fuel utilization Operating temperature 1.01 bar 50 kW 0.8 V 5% 2% 121 cm2 80% 550◦ C Table 3. Results of the system. Parameter Value Electrical efficiency Heating efficiency Combined efficiency Inverter efficiency Number of cells 49.5% 27.6% 77.1% 92% 450 - Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. F. Hussain et al. AC power is achieved. Remaining portion of unused fuel due to intrinsic behavior can be reprocessed to anode inlet. Heat of system is used for preheating of fuel, air and building space heating and cooling demands. Fuel and air utilization can be defined through Eqs. (1) and (2). Commercial SOFC fuel utilization is between 75% to 85%.49 Rise in air temperature is almost 100◦ C because it is also used for cooling purpose.49 Uf = UO2 = moles of hydrogen consumed , moles of hydrogen supplied (1) moles of oxygen supplied with air . moles of oxygen needed for stoichiometry (2) Performance of fuel cell is presented with the function of current density to obtain cell voltage as shown in Eq. (3), where E◦ is cell reversible voltage, T is temperature of fuel cell, F is Faraday constant, R is total cell resistance and iL is limiting current density.50 i i RT RT ln ln 1 − − iR − , (3) E = Eo − nF io nF iL where the 1st component of equation in right-hand side represents the electrochemical reverse voltage of the cell, the 2nd component represents the activation losses and 3rd component of the equation exhibits the ohmic losses. It is assumed in this study that there are no losses in the system. On the basis of higher heating value (HHV) of fuel, different kinds of efficiencies can be calculated as given in Eqs. (4)– (6). These efficiencies are related to DC power generated at fuel cell (PDC ), the net AC power supplied to the departments building (PAC ) and combined heat and power (PAC + Qrec ). ηSOFC = PDC , nfuel,in ∗ HHV fuel (4) ηsys = PAC , nfuel,in ∗ HHV fuel (5) ηCHP = PDC + Qrec . nfuel,in ∗ HHV fuel (6) According to total load demand of DEE, 50 kW is essential for installation to fulfill the load demand. For DME, the total load demand is 40 kW, and for that the module will contain 8 stacks of fuel cell to fulfill the load demand. However, this module can provide 10 kW more power for extraordinary activities at DME. 3.3. Thermal to electric ratio The heating TER was defined as a ratio of maximum hourly heating of space demand to average hourly basic electric power demand in kW. Similarly, cooling TER was defined as a ratio of maximum requirements of cooling to basic electric- Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Modeling approach with experimental investigation for LTSOFC Fig. 7. (Color online) TER for space heating. power demand at the same hour in kW. The TERs for space heating and cooling can be calculated by the equations given below correspondingly in Eqs. (7) and (8) TERheating = Ethermal /Eelectric , (7) TERcooling = Ecooling /Eelectric . (8) The TERs for heating and cooling of space are shown in the Figs. 7 and 8. The TER for heating of space varies between 0.27 to 4 for DEE, and 0.25 to 3.4 for DME. It is profitable when TER defined for the source of energy generation and TER defined for user demands are identical. Although, if both TERs were similar, it does Fig. 8. (Color online) TER for space cooling- F. Hussain et al. Table 4. Average daily and yearly TERs. Daily average TER Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Departments Yearly average TER Heating TER Cooling TER Heating TER Cooling TER 1.38 1.24 1.31 1.22 0.29 0.26 0.33 0.31 DEE DME not mean that all necessities would be achieved. It is because TER is an average index and both electric and thermal demand of loads can have different fluctuations during the time. Such kind of problem was already heightened in the work of Krist and Gleason.51 However, in our work, the daily and yearly average TER of department’s requirements can be shown in Table 4. The heating TER of daily average and yearly average for DEE varies from 1.38 to 0.29 and for DME it varies from 1.24 to 0.26. The cooling TER of daily average and yearly average for DEE varies from 1.31 to 0.33 and for DME it varies from 1.22 to 0.31. In Krist and Gleason, results of the yearly average TER of a residential building are near 1, while for the similar load the hourly average of TER can deviate between 0.2 and 9.51 In the work of Skowroński, this fluctuation is even higher.33 3.4. Cost analysis A model of fuel cell stack cost analysis has been prepared on the basis of the price of each cell component including the capital cost. Initially, the cost of BCFZ anode, NK-CDC electrolyte, BSCF cathode, was proposed and then for the fuel cell used here. Also, it has been found that BCFZ anode has showed reliable open circuit voltage (OCV), power density with hydrogen (fuel) and air (oxidant) at comparatively low-temperature of 550◦ C. This is the unique electrode, which has identified a competitive alternative runner to interchange the conventional electrode (Ni-YSZ) in SOFC. Relatively, its cost has been established as the most economical in all characteristics including power cost, raw materials, laboratory cost, shipment, researcher’s salaries and others. The BCFZ anode current estimated ground cost has been calculated 19A C per 20 g, for NK-CDC electrolyte the cost estimated here is 19A C per 20 g, and for BSCF cathode its estimated cost is 100A C per 20 g for fine powder and its cost can be further reduced by large scale manufacturing. As the most dominant part of the fuel cell is BCFZ anode in terms of powder usage, its cost is important here. In contrast, the cost of conventional (Ni-YSZ) electrode as stated on Sigma Aldrich website is 33.6A C per 10 g powder.52 The current cost of BCFZ anode powder expose that the BCFZ anode is more than 50% cheaper than that of conventional (Ni-YSZ) electrode on small scale manufacturing. The estimated cost of a single cell and stack can be shown in Table 5. Normally, stack cost is around 40% to the capital cost of SOFC-based system,53 therefore capital cost of the proposed system becomes 32250A C- Modeling approach with experimental investigation for LTSOFC Table 5. Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 02/13/19. Re-use and distribution is strictly not permitted, except for Open Access articles. Item Anode (BCFZ) Cathode (BSCF) Electrolyte (NK-CDC) Others Estimated cost of a single cell and stack. Weight (g) Price (A C) Price (PKR) - Any extra - - - - Cost of all components for single cell Total cost of single thin film cell Cost of Interconnectors Total cost of Stack (45 cells = 5 kW) Total cost of Module (10 stacks = 50 kW) Total Capital cost of the System 4. Conclusion The purpose of this study was to model and explore the fuel cell technologies to compete with the ongoing conventional energy systems. A theoretical approach has been developed to optimize the model of SOFC-based m-CHP system. To cover at maximum of the application demand, a system has also been developed. It is quite difficult to develop an optimized model for a CHP system because the load demand of thermal power can be distinct from the electric power. Furthermore, the combined heat and power systems have normally different responses for variations in the generation of heat as well as electric power. Generally, the efficiency is higher for the colder locations than for the warmer location of an SOFC-based m-CHP units. The main reason behind this is higher requirements of heat, which turns CHP unit more efficient. In terms of operation strategy for warmer and colder locations, as a whole the comparison of efficiency is not affected. Acknowledgments The financial support under the Indigenous 5000 scholarship scheme Vide PIN No-EG1-388 from Higher Education Commission (HEC) of Pakistan is acknowledged. 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