Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels

Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels Bioenergy systems for the future 15 low temperature solid oxide fuel cells with bioalcohol fuels

Low-temperature solid oxide fuel cells with bioalcohol fuels 15 Rizwan Raza*,†, Muhammad Kaleem Ullah*, Muhammad Afzal†, Asia Rafique*, Amjad Ali*, Sarfraz Arshad*, Bin Zhu†,‡ *COMSATS Institute of Information Technology, Lahore, Pakistan, †KTH Royal Institute of Technology, Stockholm, Sweden, ‡Hubei University, Wuhan, PR China Abbreviations AFC ALD DAFCs DCFC DEFC DESOFCs DMFC DMSOFCs EDX EIS FC FESEM HRTEM LTSOFC MCFC OCV PAFC PEMFC SDC SEM SOFC TEM XRD alkaline fuel cell atomic layer deposition direct alcohol fuel cells direct carbon fuel cell direct ethanol fuel cell direct ethanol solid oxide fuel cells direct methanol fuel cell direct methanol solid oxide fuel cells energy-dispersive x-ray spectroscopy electrochemical impedance spectroscopy fuel cell field-emission scanning electron microscope high-resolution transmission electron microscopy low-temperature solid oxide fuel cell molten carbonate fuel cell open-circuit voltage phosphoric acid fuel cell proton exchange membrane fuel cell samarium-doped ceria scanning electron microscopy solid oxide fuel cell transmission electron microscopy X-ray diffraction Symbols ˚ A atm °C eÀ G angstrom (10À10 m) atmospheric pressure, (0.1 MPa/1.013 bar/760 mmHg (Torr)) degree celsius electron Gibbs free energy (or negative thermodynamic potential) Bioenergy Systems for the Future http://dx.doi.org/10.1016/B978-0-08-101031-0.00015-6 © 2017 Elsevier Ltd All rights reserved 522 Bioenergy Systems for the Future MPa mL mm n nm mW cmÀ2 V C Ce Cu H Li N Na Ni O O2À Sm Zn mega Pascal milliliter millimeter (10À3 m) number of cells in a fuel-cell stack or number of moles nanometer (10À9 m) milliwatts per square centimeter volt carbon cerium copper hydrogen lithium nitrogen sodium nickel oxygen oxide ion samarium zinc Greek Letters α η λ θ alpha (charge-transfer coefficient) eta (efficiency) lambda (stoichiometric ratio) the diffraction angle in degrees 15.1 Introduction Most of the energy requirements are fulfilled by natural resource of fossil fuels such as coal, oil, and natural gas, which are limited resources in their nature and are reducing rapidly Therefore, upmost need is to develop an energy strategy for the future of the world including Pakistan, which is economically sustainable and environment friendly The best possible solution may be to reduce the world’s energy dependence on nonrenewable resources Most of the industrial development is created using fossil fuels; however, there is also known technology that uses other types of renewable energies—such as steam, solar, and wind The world is shifting its attention to harness nonconventional energy resources as mentioned above, for example, solar power, wind power, tidal, hydropower, geothermal, and biomass using FC technology FC is considered as one of the key elements of the “hydrogen economy,” in which hydrogen generated from renewable energy resources would be widely used as a clean energy carrier (Bockris, 2013) It does not produce greenhouse gases and other pollutants during its operation, and it has a higher efficiency entitlement (no Carnot cycle limitations) and lower maintenance (no moving parts) cost than internal combustion engines (Srinivasan, 2006) Low-temperature solid oxide fuel cells with bioalcohol fuels 523 On the basis of operating temperatures, FCs can be divided into three categories In the first category, alkaline fuel cell (AFC), direct methanol fuel cell (DMFC), and proton exchange membrane fuel cell (PEMFC) have an operating temperature below 200°C In the second category, phosphoric acid fuel cell (PAFC) has an intermediate operating temperature range of 200–250°C In the third category, solid oxide fuel cell (SOFC), direct carbon fuel cell (DCFC), and molten carbonate fuel cell (MCFC) have operating temperature above 500°C (Li et al., 2009) In various applications, fuel cells are widely recognized as “very attractive devices” to obtain direct electric energy from the electrochemical reactions of chemical products Low-temperature fuel cells using hydrogen as a fuel, which generally utilize proton transport electrolyte membranes, seem to be also of utility for large power applications However, the final choice of the fuel is still difficult and depends greatly on the field of application (Li et al., 2003) Ethanol produced from pretreatment and microbial fermentation of biomass has great potential to become a sustainable transportation fuel in the near future First generation biofuel focuses on starch (from grain) fermentation, while there has been many processes developed over the years that can technically produce the ethanol from wheat biomass, there remain significant economic barriers to full-scale commercialization of starch to ethanol processes Recent developments in industrial biotechnology have resulted in the exploitation of new and undiscovered microorganisms and the devising of improved methods for enzyme production, which have led to increase yields of the enzyme, thus making a viable industrial process feasible (Blieva, 2003, 2004, 2005) Agriculturally derived fuel ethanol will only displace large quantities of petroleum, if abundant biomass sources, such as fibers, grasses, straws, and grain middling, are converted to ethanol via cost-effective isolation of fermentable sugars, which is presently costly (Eggeman and Elander, 2005) This is most efficiently done enzymatically; however, commercially available enzymes are bit expensive, have low activity, meaning too much enzyme is required, and often produce low sugar yields The proposed research focuses on new, more versatile, microorganisms capable of squeezing more ethanol from biomass to further reduce the projected bioethanol production cost and employ the bioethanol for polygeneration integrated by advanced fuel-cell technology The bioethanol can be produced from biomass such as trees and grasses, which contain cellulose The biomass to bioalcohol process integrated with fuel cell is described in schematic of Fig 15.1 In the 1960s, Thomas Grubb and Leonard Niedrach of General Electric (Arbizzani et al., 2006) invented the PEMFC, and they exhibited it as possible to convert chemical energy of natural fuels, such as hydrogen, into electric energy directly Due to the problems related to hydrogen storage, the bioalcohol (biomethanol and bioethanol)-based fuel cell may be the best choice for different applications DAFCs have attractive enormous attention as power source for portable electronic devices and transportation This attention toward bioalcohol fuels is due to relatively lower prices, human protection, and easiness of storage and much higher energy density than gaseous fuels such as hydrogen and natural gas DAFCs may ensure to declare Bioenergy Systems for the Future Bioethanol 524 SOFC Power Biomass Biomethanol Heat Low Temp (400–600)ЊC Fig 15.1 Schematic diagram of bioalcohol fuel-cell system an oil independence and speed oil-free state after maturity status Additionally, the proposed FC system can make strong contributions to reduce the greenhouse effect by significantly reducing CO2 emission from power generation and transportation This FC can increase the use of the renewable energy for our society, and results achieved within the system have great potential to revolutionize the energy technology in an environmentally friendly and sustainable way (Volkmar et al., 1996) In low-temperature FC, methanol can be converted into hydrogen-rich mixtures via several reactions, including pure methanol thermal cracking: CH3 OH ¼ CO + 2H2 (15.1) Partial oxidation is given as 2CH3 OH + O2 ¼ 2CO2 + 4H2 (15.2) However, carbon forms are given as 2CO ¼ C + CO2 (15.3) Methanol steam reforming is given as CH3 OH + H2 O ¼ CO2 + 3H2 (15.4) Water-gas shift reaction is given as CO + H2 O ¼ CO2 + H2 (15.5) Low-temperature solid oxide fuel cells with bioalcohol fuels 525 The most prominent features of DAFCs are environment friendly (low emission), noises are minimum (no moving parts involved), and useful heat, pure water, and very low quantity of CO2 are the only by-products Two types of DAFCs are discussed below separately 15.1.1 Direct methanol fuel cell The biomethanol or direct methanol fuel cell produces electric power by direct conversion of biomethanol and therefore is called “the electrochemist’s dream” and “the ideal fuel-cell system” (Hogarth and Hards, 1996) Biomethanol is favorable for SOFC due to its ready availability, high specific energy, and storage transportation convenience A DMFC combines the properties of direct hydrogen/air fuel cells with the advantages of an alcohol fuel Because it is a liquid, it can be transported and stored easily Methanol needs no any cryogenic container maintained at a temperature of À253°C Methanol is cheap, plentiful, and easy to manufacture Moreover, it has a higher energy density as compared with hydrogen gas (Vielstich et al., 2003; Prabhuram et al., 2015) During the oxidation process, aqueous solution of methanol releases six electrons and six protons per molecule (see Table 15.1) Methanol is known as a suitable fuel for fuel cell because of its number of properties like high energy density, clean liquid fuel, larger availability at low cost, easy to handle and distribute, made from natural gas and renewable resources, economically viable option, and possible direct methanol operation fuel cell The LTSOFC fed by methanol is an extraordinary good clean energy carrier combined heat and electricity Recently, reasonable achievements are obtained in literature to optimize the application of DMFC Bimetallic nickel/ruthenium-based catalysts are prepared through ALD technique for low-temperature (300–400°C) DMSOFCs, and the fuel-cell performance achieved is close to the DMSOFCs using platinum/ruthenium-based catalysts ( Jeong et al., 2016) Similarly, SOFC using water/methanol (1:1) as fuel and ambient air as oxidant has shown a power density of 431–603 mW cmÀ2 at 500–600°C, and results are comparatively little less than that of hydrogen fuel (Gao et al., 2011; Liu et al., 2008) Some other relevant works are also reported Table 15.1 Reactions of popular liquid fuels for DLFC Methanol Anode Cathode Overall Anode Cathode Overall Ethanol CH3OH + H2O ! CO2 + 6H+ + 6eÀ 3/2O2 + 6H+ + 6eÀ ! 3H2O CH3OH + 3/2O2 ! CO2 + 2H2O C2H5OH + 3H2O ! 2CO2 + 12H+ + 12eÀ 3O2 + 12H+ + 12eÀ ! 6H2O C2H5OH + 3O2 ! 2CO2 + 3H2O Vielstich et al (2003) Shuqin and Panagiotis (2006) 526 Bioenergy Systems for the Future showing promising results of direct methanol SOFCs for their potential applications (Faro et al., 2011; Sahibzada et al., 2000) 15.1.2 Direct ethanol fuel cell Bioethanol fuel cell is based on solid oxide membrane (electrolyte) The membrane of FC is negative ion conductor, in which O2À ions due to reduction process at cathode will pass through the electrolyte from cathode to anode to form water as a by-product along with low concentration of CO2 The total reaction of ethanol oxidation in a fuel cell is described by Eq (15.6): C2 H5 OH + 3O2 ! 2CO2 + 3H2 O (15.6) Ethanol is a very useful fuel for fuel-cell technology It is cleaner than conventional oil-like petroleum Unlike fossil fuels, it is a renewable and sustainable resource It is carbon neutral and biodegradable and far less toxic than fossil fuels if accidentally split outdoors The usage of ethanol or fuel-flexible engines will reduce the emission of carbon compounds by 80% and the one of CO2 by 30% Previous studies have proved that alcohol fed FCs or DM/DE-SOFCs are promising devices for safe energy conversion (Mat et al., 2007; Morales et al., 2015) Thermodynamic studies of SOFCs operated with direct methanol and ethanol as fuel, steam reforming, and dry reforming under partial oxidation conditions reveal their potential use in portable applications (Cimenti and Hill, 2009) Bioethanol fuel cell is operated at high temperature SOFC has its significance due to provision of thermal assimilation (Imran et al., 2011) The performance and comparison of the carbon content deposition before and after test are examined in detail The purpose of this chapter is also to study the low working temperature range in between 450°C and 600°C The advantages of the direct alcohol fuel cells over conventional hydrogen-oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety The detailed literature survey has been reviewed and observed; most researchers have studied bioalcohol FC at high temperature even more than 700°C Only methanol has been tested at low temperature especially in PEMFC The details of performance with different materials and temperature have been shown in Table 15.2 Maximum power densities have been achieved at high temperature compared with low temperature as seen from above summarized table But high cost, complex fabrication, and thermal challenges are the main drawbacks of high-temperature operation in SOFC, which convince the scientists to work on low-temperature SOFC The nanocomposites that can be used for alcohol-based fuel cell can be synthesized via different routes and are characterized using various technologies, for example, XRD, SEM, and TEM These materials are also electrochemically characterized to find their electrochemical impedance by EIS technique, ionic and electronic conductivity by four-probe method and fuel-cell performance, for example, power density, etc The materials and performance analysis at different temperature Fuel cell type Operating temp (°C) Performance (mW cm22) Anhydrous ethanol SOFC 850 47 Nobrega et al (2012) Biomethanol SOFC 750 350 Elleuch et al (2016) Ethanol-air mixture SOFC 450 50 Morales et al (2015) Ethanol SOFC 850 400 Yan et al (2014) Methanol SOFC 750 259 Hu et al (2014) Methanol SOFC 800 350 Faro et al (2011) Ethanol SOFC 750 350 Wang et al (2014) Ethanol SOFC 750 953 Wang et al (2015) Fuel type Electrolyte—YSZ Anode—NiO–YSZ Cathode—LSM Anode—nickel-SDC Electrolyte—SDC mixed with Li2CO3/Na2CO3 Cathode—SDC mixed LixNi1À xO Anode—I-doped ceria Electrolyte—gadolinium-doped ceria Cathode—La0.6Sr0.4CoO3À δ-doped ceria Anode—Ni-YSZ Electrolyte—YSZ Cathode—LSM (La0.8Sr0.2MnO3À x)-YSZ Anode—Sn-YSZ anode Electrolyte—(ZrO2)0.92(Y2O3)0.08 Cathode—La0.6Sr0.4Co0.2Fe0.8O3 Anode—I/La0.6Sr0.4Fe0.8Co0.2O3 Ce0.9Gd0.1O2 Cathode—LSFCO and CGO in ratio (70:30) Anode—Ni + YSZ Electrolyte—YSZ Cathode—BSCF-SDC Anode—NiO + BaZr0.1Ce0.7Y0.2O3À δ and NiO + BaZr0.1Ce0.7Y0.1Yb0.1O3À δ Electrolyte—SDC Cathode—Ba0.5Sr0.5Co0.8Fe0.2O3À δ and Sm0.5Sr0.5CoO3Àδ References 527 Material Low-temperature solid oxide fuel cells with bioalcohol fuels Table 15.2 528 15.2 Bioenergy Systems for the Future Case study of the research As a case study, the preparation of the electrodes and electrolyte by using different nanocomposite materials of the bioalcoholic fuel cell is discussed below Results of the characterization and performance of fabricated FC are also discussed 15.2.1 Preparation of electrolyte and electrodes for bioalcohol FC For the preparation of nanocomposite electrolyte, SDC nanocomposite with sodium carbonate is commonly used To synthesis SDC, solution (A) of molarity 0.05 mol is prepared from starting chemicals Sm(NO3)3 Á 6H2O and Ce(NO3)3 Á 6H2O (the molar ratio between the samarium and ceria is kept 1:4) To get precipitates of SDC using sodium carbonate, another solution (B) of Na2CO3 with molarity 0.1 mol is prepared and is poured solution (B) into SDC solution (A) dropwise according to the required molar ratio 1:2 for SDC/Na2CO3 while stirring The precipitates are washed and filtered following a drying overnight in the oven at 80°C The dried material is sintered for h at 800°C in a furnace, and after cooldown, the dried material is crushed in a mortar with pestle (Raza et al., 2010a; Ying et al., 2010) The electrodes are prepared by solid-state reaction method The chemicals are used as Li2CO3, CuCO3 (OH)2, NiCO3, and nitrate Zn(NO3)2 Á 6H2O These are mixed with stoichiometric amount of molar/weight ratio and ground in a mortar The resultant mixture is sintered at 800°C for h Oxides of nickel and copper are commonly used as anode catalyst because they have good catalytic activity especially for direct conversion of hydrocarbon fuels The prepared electrodes are mixed with the electrolyte, by 50% volume ratio This enhances the catalytic property of the anodic toward bioalcohol fuels, for example, biomethanol and bioethanol (Imran et al., 2011) The FCs can be fabricated with different diameters in, that is, 13 and 20 mm, respectively Dry powder press method is used for the preparation of cell pellet having 13 mm diameter with active area of 0.64 cm2 The fuel cell made by this method consists of anode (composite with electrolyte)-electrolyte-cathode (composite with electrolyte) The thickness of the cell is about mm, where the anode thickness is about 0.5 and 0.25 mm for the electrolyte and cathode The fuel cell is made by pressing the three components in the hydraulic press at pressure of 250 MPa The sizes of the anode, electrolyte, and cathode are mentioned in Fig 15.2 Then, pellets are sintered in a tubular furnace at 600°C for h Before testing, the cells are painted with silver paste on both sides to improve the electric contact 15.2.2 Hot press method (preparation of cell with diameter of 20 mm) In hot-press method, films are prepared instead of dry powder The film technology is considered the first step in producing the fuel cell on the large scale For the formation of film, first, we need to prepare the powder and then add some chemical/binder that Low-temperature solid oxide fuel cells with bioalcohol fuels Nickel foam Silver paste 0.3 mm 0.3–0.5 mm 0.5 mm 529 Metal treated with silver Cathode powder Cathode film Electrolyte powder Electrolyte film Anode powder Anode film Metal treated with silver Silver paste Nickel foam (A) (B) Fig 15.2 Schematic representation of (A) dry press pellet (B) hot press acts as a chemical adhesive but may not change the chemical properties of the material and decrease the device performance Due to the increase in the dimension of pellet, electron collection may be a problem The hot-press method creates a pellet of 20 mm corresponding an activated area of about cm2 Same as in the dry-press method, the pellet is prepared by anode, electrolyte, and cathode layer successively The silver paint is replaced by stainless steel net coated by silver Sometimes, nickel foam can be placed on outer side of the pellet as current collector Then, the FCs are pressed under the pressure of 200 MPa at a temperature of 600°C for h, finally to form a film of 0.2 mm in thickness 15.2.3 Fuel cells performance Bioethanol and air are used as a fuel and an oxidant, respectively The fuel flow rate is controlled at about 50–100 mL minÀ1 (10 drops minÀ1) Airflow rate is at about 200 mL minÀ1 under atm pressure Testing device consists of two u-shaped pipes, pellet (cell) fixed in the device, with air and fuel gases in and out tubes as shown in Fig 15.3 The fuel-cell performance is measured using a computerized instrument (IT8511 +, Ed, Electronics Co., Ltd) Hydrogen is used as the fuel supply at a flow rate of 80–150 mL minÀ1 and air as the oxidant at 150–220 mL minÀ1 under atm 15.2.4 Microstructure analysis of the NSDC (electrolyte) Powder XRD patterns of the sample is collected from a Philips x-ray diffractometer ˚ ) for phase analysis and crystal size calculation with Cu Kα radiation (λ ¼ 1.5418 A A Zeiss ultra 55 FESEM is used to examine the morphology and microstructure of 530 Bioenergy Systems for the Future Air Hydrogen Ag Cathode Nickel foam (current collector) Electrolyte Anode Ag Fig 15.3 Schematic representation of the fuel-cell measurement device samples The HRTEM is performed on a JEOL JEM-2100F microscope with a field emission gun operating at 200 kV (Raza et al., 2010b) to measure the particle size 15.2.5 Microstructure analysis of the cell before and after testing with bioethanol fuel The fabricated cells are analyzed before and after testing with bioethanol fuel for observation of carbon deposition and structure of the cell The detail structural and electrochemical analyses are discussed in following parts 15.2.5.1 Phase/crystal structure analysis by XRD The prepared sample of SDC-Na2CO3 was analyzed for phase/crystal structure XRD pattern samarium atoms have fully doped into lattice of CeO2, but small shift in the ceria peak is found due to doping of samarium into CeO2 because these peaks completely match with the cubic fluorite structure of CeO2 (JCPDS 34-0394 card) There are no XRD reflections detected for the carbonate The carbonate component was found to be amorphous and highly distributed among the SDC The average particle size calculated by Scherrer’s formula is 14 nm from (111) peak of the XRD pattern in Fig 15.4, which provides an evidence that SDC-Na2CO3 is a nanocomposite electrolyte material 15.2.5.2 Fuel cell performance with bioethanol/biomethanol The performance of the low-temperature SOFC was measured with bioalcohol fuel (biomethanol and bioethanol) Maximum power densities of 600 and 550 mW cmÀ2 are obtained for the single cells at 550°C, using biomethanol and bioethanol, respectively, as shown in Fig 15.5 Low-temperature solid oxide fuel cells with bioalcohol fuels 531 N-SDC (111) 20 (311) (200) (331) 30 40 (222) (400) 60 70 50 2q 420 Intensity (a.u) (220) 80 Fig 15.4 It shows the peak values of XRD for the prepared samples The performance of cell using biofuels (biomethanol and bioethanol) at different temperatures (400°C, 450°C, 500°C, and 550°C) confirms that the internal reforming of these biofuels is more active at higher temperatures (550°C) The catalytic improvement that results from the addition of ZnO to the anode materials can significantly improve the performance of liquid-fuel (biomethanol and bioethanol)-based LTSOFCs, and the fuel can be internally reformed in addition to 500 1000 1500 2000 Biomethanol Bioethanol 1.0 2500 600 Voltage (V) 0.8 400 0.6 0.4 200 Power density (mW cm−2) 0.2 0.0 500 1000 1500 Current density (mA cm−2) 2000 2500 Fig 15.5 Performance of single cells with biofuels at temperature 550°C (Raza et al., 2011) 532 Bioenergy Systems for the Future the direct oxidation process of the fuel cell, which implies a degree of flexibility with respect to various fuels The functional nanostructure of the electrode may afford the potential to provide a high power density through the direct use of liquid fuels or hydrocarbons without the occurrence of carbon deposition The use of liquid and gaseous fuels can offer several advantages including internal reformation Based on the Nernst equation, the theoretical calculated open-circuit voltages (OCVs) for the two different biofuels are 1.13 and 0.995 V at 550°C The equivalent experimental OCVs of the cells were 1.09 and 0.98 V A comparison between the theoretical and experimental values of OCV is shown in Fig 15.6 It confirms the catalytic activity of the anode in the oxidation of biofuels There is no polarization of the electrode, as shown in Fig 15.5 The lower reduction in IR as a result of the ohmic behavior of the electrolyte may be responsible for the high performance at such low temperatures In general, the high performance of these SOFCs corresponds with linear I-V characteristics Fig 15.7 shows the chemical stability of the cell with both liquid fuels at 550°C in the absence of any coke formation or carbon deposition The stability of OCVs of the cells with different fuels was tested for 2500 It can be seen that, for these fuels, after 200 min, the OCVs were almost stable and did not fluctuate distinctly in the whole testing period, which demonstrates the stability of the cell with these fuels Because the performance of the cell may be reduced due to carbon deposition on the pores of the electrode material, but it is not the case for the cell discussed here at operational temperatures from 500°C to 520°C It may be seen that the main advantage of these alcohol SOFCs is the direct oxidation that occurs without any reforming of the biofuel into pure hydrogen, and this reduces the cost and complexity of the system and the conversion efficiency Direct Biomethanol(Exp) Biomethanol(Theo) Bioethanol(Exp) Bioethanol(Theo) 1.19 1.12 OCV (V) 1.05 0.98 0.91 0.84 0.77 0.70 550 600 650 700 750 Temperature (K) 800 850 900 Fig 15.6 OCV comparison of calculated theoretical values and obtained experimental values with different biofuels at temperatures 500–550°C (Raza et al., 2011) Low-temperature solid oxide fuel cells with bioalcohol fuels 533 1.05 1.00 OCV (V) 0.95 Biomethanol Bioethanol 0.90 0.85 Operating temperature from 500∞C − 520∞C 0.80 0.75 0.70 500 1000 1500 Time (min) 2000 2500 Fig 15.7 SOFC stability with different biofuels at temperatures 500–520°C (Raza et al., 2011) oxidation is only valid when the anode of the cell is inert and free of carbon deposition LiNiCuZn anode therefore has the ability to catalyze the carbon to avoid the carbon deposition in the anode of the cells 15.2.5.3 Scanning electron microscopy The image of the electrode shows that the nanocatalytic particles are distributed homogenously in the range of 10–15 nm and nanoparticles are interconnected (Fig 15.8) The cell was analyzed by XL-30 SEM The SEM image shows that the Fig 15.8 SEM Image (Imran et al., 2011) 534 Bioenergy Systems for the Future microstructure of the electrode is porous, which allows the rapid transport of gas through the nanopores This occurs as a result of the high specific surface area, which is highly active and catalyzed by the Zn The purpose of the addition of “Zn” is to help to oxidize the hydrogen and to improve the electronic and ionic conductivity of the electrode The morphological and structural distributions are likely to facilitate the transfer of charge through the circuit SEM analysis of the cell before test A complete three-layer cell was analyzed before and after testing with bioethanol fuel This system of analyzing is adopted due to the use of bioethanol fuel Because bioethanol fuel deposits carbon layer on the cell electrode with the passage of time, the basic aim is to observe this carbon quantity after test Fig 15.9 shows the different egg-shaped particles of different sizes Some are larger, and some are smaller particles; the larger particles show clear existence of pure electrolyte in the cell, while smaller particles are very close together that show the mixture of electrode and electrolyte called composite electrode This work depends on the nanocomposite theory; so the powder to fabricate the cell is nanosized though it was pressed within three layers and sintered at certain high temperature in the range of 550–600°C Its structures remain the same, which shows the nanosize particles of the cell There was about 10% carbon found in a cell; this is because of some carbon mixed in the electrodes at the time of cell fabrication in order to form a porous structure SEM analysis of the cell after test As discussed above, using the same cell after the alcohol fuel-cell operation, it can be seen that the particle size maintains nanorange, and the device electrodes’ layers are free from any carbon deposition in case of using the bioethanol operation In initial Fig 15.9 SEM analysis before test (Imran et al., 2011) Low-temperature solid oxide fuel cells with bioalcohol fuels 535 fabrication of the fuel cell, a carbon layer over the surface of the cell is deposited The major aim to characterize the cell after test was to observe any changes for this deposition layer As in previous SEM analysis that has larger and smaller egg-shaped spheres, Fig 15.8 does not show the sphere instead a smooth layer of the carbon to prove this carbon layer EDX analysis proves the existence of carbon with the presence of cerium and samarium These elements were numerically described as C, O2, Na, Ni, Sm, and Ce The carbon was found about 10%–12% in the cell Only 1%–2% additional carbon has been found Fig 15.10 shows a mixture of material on the surface of anode and cathode This added material does not change the structure and size of the particles but shows an overlapping mechanism; by analyzing of EDX, it has been observed that this overlapping is the prepared deposition of carbon layer, while Sm, Ce, and Zn, also shown in EDX from the starting oxide materials The observed percentage amount of the element is shown in Table 15.3 This detailed analysis proves again no significant carbon formed from the alcohol operation Elemental analysis (with composition) Table 15.3 Element Atomic% Carbon (C) Oxygen (O2) Sodium (Na) Nickel (Ni) Zinc (Zn) Cerium (Ce) Samarium (Sm) 10.5 61.76 4.45 11.08 6.2 5.4 0.61 Spectrum 100 μm Fig 15.10 SEM image after test with EDX analysis 536 Bioenergy Systems for the Future 15.2.5.4 Electrochemical impedance analysis AC impedance spectroscopy is used to determine the resistance and conductivity of SOFCs using biomethanol and bioethanol fuels The Nyquist plots of the cell for both fueled devices at 500°C are shown in Fig 15.11 The plots show a single semicircle at low frequencies, displaying the complex behavior of the electrode and the diffusion in the electrolyte The intercepts along the real axis are the sum of the ionic resistance of the electrolyte and the electronic resistance of the electrodes and the silver paste current collectors The ohmic resistance of the cell at the intercept with the abscissa is about 0.61 Ω for biomethanol and 0.73 Ω for bioethanol Cell efficiency Theoretical electric efficiency of the fuel cells for biomethanol and bioethanol fuels can be calculated as ηmax power ¼ ΔG ÀnFEel  100% ¼  100% ΔH ΔH (15.7) The calculation of OCV The OCV can be determined using the Nernst equation:   1=2 E ẳ Eo + RT=2Fị ln PH2 =PH2 O Þ + ðRT=2FÞ ln PO2 Bioethanol Biomethanol 0.04 Zim(Ω) (15.8) 0.02 0.00 0.6 0.7 Zre(Ω) 0.8 Fig 15.11 Nyquist plot at open-circuit voltage (500οC) (Raza et al., 2011) Low-temperature solid oxide fuel cells with bioalcohol fuels 537 where, Eo is open-circuit voltage (OCV) at standard pressure; R is gas constant; F is Faraday’s constant; T is operating temperature; PO2 is partial pressure of oxygen; PH2 is partial pressure of hydrogen; PH2O is partial pressure of water vapors It may be seen that OCV depends on the cell temperature and the concentration of hydrogen, water, and oxygen at the anode and cathode 15.3 Case study of the application A typical bioalcohol fuel-cell application can refer to automobile Japanese car Nissan Motor Co has presented its research highlight developing a SOFC-powered car that runs on electric power generated from liquid bioethanol (produced from sugarcane, corn, etc.) It utilizes further hydrogen produced from fuel (possibly ethanol-blended water) by using reformer and oxygen, with an electrochemical reaction generating the electricity power to run the vehicle This system can use bioethanol fuel via the electrochemical reaction to generate the electric power without releasing any harmful by-products concerning the entire CO2 cycle from the bioethanol production to the electricity generation Using bioethanol, SOFC can offer an environment-friendly transportation system that can create new opportunities in energy production and public transport sectors at regional level keeping the existing infrastructure (Gustavo, 2016) 15.3.1 Working principle of the bioethanol fuel cell car system Hydrogen is produced through reformer from liquid ethanol-blended water in the reformer; mainly hydrogen and CO2 gases are obtained The SOFC stack in fuel-cell chamber is fed with this hydrogen and atmospheric oxygen as fuel and oxidant Every individual cell in the stack using hydrogen and oxygen gases through electrochemical processes produces water molecules and electricity where heat is also obtained as a by-product that is again used in the reformer for the cracking of ethanol to make the system highly efficient Combined electric power from all of the cell units of the SOFC stack is provided to the external circuit to drive the vehicle Steam water and CO2 are exhausted out of the system to maintain the operation smoothly (Gustavo, 2016) 15.4 Conclusion This book chapter describes and demonstrates advanced alcohol SOFC materials, technology, working principle, and some theoretical results It is concluded that nanocomposite materials are very suitable for low-temperature bioalcohol fuel cells The power output has been achieved between 450 and 600 mW cmÀ2 at 550°C for bioethanol and biomethanol fuels The theoretical calculations show that the electric efficiency for bioethanol is 51%, while with biomethanol is 48% These high efficiencies are attractive for polygeneration systems The typical application case is studied on the Japanese bioethanol fuel-cell car that has demonstrated great market and commercial potentials 538 Bioenergy Systems for the Future References Arbizzani, C., Beninati, S., Manferrari, E., Soavi, F., Mastragostino, M., 2006 Electrodeposited PtRu on cryogel carbon-Nafion supports for DMFC anodes J Power Sources 161 (2), 826–830 Blieva, R.K., 2003 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Material Low- temperature solid oxide fuel cells with bioalcohol fuels Table 15. 2 528 15. 2 Bioenergy Systems for the Future Case study of the research As a case study, the preparation of the electrodes... 2011) Low- temperature solid oxide fuel cells with bioalcohol fuels 535 fabrication of the fuel cell, a carbon layer over the surface of the cell is deposited The major aim to characterize the cell... 0.0 500 1000 150 0 Current density (mA cm−2) 2000 2500 Fig 15. 5 Performance of single cells with biofuels at temperature 550°C (Raza et al., 2011) 532 Bioenergy Systems for the Future the direct