Solid Oxide Fuel Cells

Das Ziel dieser Arbeit war, das Anwendungspotential der Wasserstofftechnologien auf Kläranlagen aufzuzeigen. Wie bereits in der Einleitung dieser Arbeit erwähnt, ist zum Schutze des Klimas eine massive Minderung der von uns Menschen erzeugten CO2-Emissionen erforderlich. Das heisst, dass die derzeitigen primären, fossilen und auch endlichen Energieträger durch nachhaltige, erneuerbare Energieträger, wie z.B. Windkraft, Photovoltaik, etc., ersetzt werden müssen. Der Ausbau der erneuerbaren Energien und die Reduzierung der Treibhausgase um 80 % bis zum Jahr 2050, sind klare Ziele der deutschen Bundesregierung. Der Ausbau der erneuerbaren Energien hat zur Folge, dass grosse Kapazitäten an elektrischer Energie als Überschussenergie vorhanden sein werden. Diese Überschussenergie gilt es für nachhaltige Prozesspfade sinnvoll einzusetzen. Einer dieser Pfade stellt die Umwandlung der Überschussenergie in „Power-to-X“ mittels diverser Wasserstofftechnologien dar. Wasserstoff wird im Rahmen der Dekarbonisierung wieder als idealer sekundärer Energieträger für eine schadstofffreie Energieversorgung gehandelt. Kläranlagen sind grosse Energieverbraucher, aber auch potentielle Energieerzeuger. Der Standort Kläranlage bietet sich, aufgrund seiner bestehenden Infrastruktur, hervorragend für die Implementierung der Wasserstofftechnologie an. Zur Herstellung von Wasserstoff gibt es viele verschiedene Verfahren. Auf Kläranlagen hat sich bisher gezeigt, dass die Wasserdampfreformierung und die Wasserelektrolyse für die Herstellung von Wasserstoff Stand der Technik sind. Der Unterschied zwischen beiden Verfahren ist, dass für die Wasserdampfreformierung eine ausreichend grosse Faulgasmenge zum kontinuierlichen Betrieb der Dampfreformierung notwendig ist. Bei der Wasserelektrolyse gibt es mit der alkalischen - und der PEM-Elektrolyse zwei kommerzielle Typen von Elektrolyseuren, welche sich auf Kläranlangen in kommerziellen Projekten bewiesen haben. Abhängig vom Leistungsbereich, von den Investitionskosten und vom Platzangebot auf der Kläranlage, ergeben sich für den Einsatz von Elektrolyseuren kläranlagenspezifische Entscheidungen. Die hier angegebenen Systemwirkungsgrade der Elektrolyseure liegen in Wirklichkeit viel höher, da zum einen ihre Abwärme auf der Kläranlage, z.B. für den Faulbehälter, verwendet werden könnte und zum anderen können sie bei Überschussenergieaufnahme eine Abschaltung der Windkraft- und Photovoltaikanlagen verhindern. Mit beiden Elektrolyseurtypen wird neben dem Wasserstoff auch Sauerstoff erzeugt. Der Sauerstoff kann stofflich im Belebungsbecken oder in der Beseitigung von Spurenstoffen mit Ozon eingesetzt werden. In beiden Fällen hätte der eingesetzte Sauerstoff eine Energieeinsparung zur Folge, weil zum einen die herkömmliche energieintensive Druckbelüftung wegfallen könnte und zum anderen für die Ozonierung der Sauerstoff nicht zusätzlich produziert oder über externe Lieferanten bereitgestellt werden müsste. Für den Einsatz von Sauerstoff auf Kläranlagen gibt es in der Literatur noch keine ausreichend praxistauglichen und belastbaren Zahlen, jedoch wird derzeit dieses Thema in verschiedenen Projekten untersucht. Der auf Kläranlagen erzeugte Wasserstoff kann zwischengespeichert und je nach Bedarf zu einem späteren Zeitpunkt rückverstromt werden. Die Rückverstromung kann über ein Wasserstoff- oder über ein Brennstoffzellen-BHKW stattfinden. Dabei kann die entstehende Abwärme für Wärmesenken, wie z.B. den Faulbehälter, die Betriebsgebäudeheizung oder die Beheizung des Belebungsbeckens im Winter, verwendet werden. Falls ein lokales Erdgasnetz vorhanden ist, besteht die
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Möglichkeit, den entstandenen Wasserstoff bis zu 2 Vol. % direkt einzuspeisen. Neben der Wasserstofferzeugung wurden auch die technischen Möglichkeiten der Speicherung von Produkten der Wasserstofftechnologie untersucht. Im Rahmen des Konzeptes „Power-to-X“ ergeben sich mehrere Möglichkeiten den Überschussstrom aus den erneuerbaren Energien zwischen zu speichern. Eine Möglichkeit besteht im Konzept „Power-to-Hydrogen“. Dabei wird der erzeugte Wasserstoff direkt, entweder in Druckbehältertanks, in Metallhydridspeichern oder über Verflüssigungsverfahren in Flüssigtanks, bis zu seiner bedarfsabhängigen Nutzung, z.B. der Rückverstromung, zwischengelagert. Da jede Speichereinheit ihre Vor- und Nachteile hat, ist die Wahl des richtigen und wirtschaftlichsten Speichers kläranlagenspezifisch zu prüfen. Eine weitere Möglichkeit besteht im Konzept „Power-to-Methan“. Dabei wird der Wasserstoff zusammen mit dem ebenfalls auf Kläranlagen vorhandenen Kohlendioxid, entweder einem katalytischen- oder einem biologischen Methanisierungsreaktor zugeführt, um dadurch ein hochwertiges Methan als Synthesegas zu erhalten. Bei diesem Prozess entsteht Abwärme die abgeführt und im Sinne einer hohen Anlageneffizienz in Wärmesenken der Kläranlage verwendet werden muss. Das entstandene Synthesegas Methan kann in Erdgastanks zwischengespeichert, in Gasmotoren- und Brennstoffzellen-BHKWs rückverstromt oder in ein lokales Erdgasnetz eingespeist werden. Eine dritte Möglichkeit besteht im Konzept „Power-to-Liquid“. Dabei wird auf der Kläranlage das Faulgas aufbereitet und zusammen mit Elektrolyse-Wasserstoff dem Methanolsynthesereaktor zugeführt. Methanol ist einfacher zu handhaben als Wasserstoff und kann einfach in Flüssigtanks bis zu seiner späteren Verwendung zwischengelagert werden. Zudem kann Methanol in Methanol-BHKWs, in Direktmethanolbrennstoffzellen rückverstromt oder Kraftstoffen beigemischt werden. Allerdings existieren bis heute weder ausgereifte Methanol-BHKWs, noch entsprechend grosse und leistungsstarke Direktmethanolbrennstoffzellen. Des Weiteren ist in Deutschland und Europa auch noch keine nennenswerte Methanol-Infrastruktur vorhanden. Für die energetischen Nutzungen der Wasserstofftechnologie gibt es sieben verschiedene Brennstoffzellentypen. Beim Einsatz von Brennstoffzellen auf Kläranlagen haben sich bisher die Festoxidbrennstoffzelle (SOFC), die Schmelzkarbonatbrennstoffzelle (MCFC) und die Phosphorsäurebrennstoffzelle (PAFC), in verschiedenen Pilotprojekten, erfolgreich bewährt. Diese drei Brennstoffzellentypen sind brennstoffflexibel und können mit aufbereitetem Faulgas betrieben werden. Die MCFC und die SOFC haben, mit durchschnittlichen 65 %, die höchsten elektrischen Wirkungsgrade und ihre entstehende Prozessabwärme kann für eine interne oder externe Reformierung verwendet werden. Die Reinigungsstufe des Faulgases stellt die grösste Herausforderung bei der Brennstoffzellentechnik auf Kläranlagen dar. Da die Zusammensetzung des Faulgases variiert und somit kläranlagenspezifisch ist, muss für die Implementierung der Brennstoffzellentechnik, im Vorfeld die Zusammensetzung des Faulgasstroms für jede einzelne Kläranlage über Zeitreihen analysiert werden. Die Mikrobielle Brennstoffzelle (MFC) stellt, unter den in dieser Arbeit beschriebenen Brennstoffzellen, einen Spezialfall dar, da in ihre Brennkammer keine Gase, sondern Abwasser einströmt, dessen Energiegehalt über den chemischen Sauerstoffbedarf (CSB) ermittelt wird. Mit der Verwendung der MFC im Abwasserbereich könnte, neben der Stromproduktion, auch die organischen Kohlenstoffverbindungen reduziert werden. Für die MFC besteht ein grosses zukünftiges Potential zur relevanten Stromproduktion auf Kläranlagen, allerdings ist dafür noch viel Forschungsarbeit notwendig. Wasserstoff kann weiterhin energetisch in Wasserstoff-BHKWs verbrannt werden. Der Wirkungsgrad der Wasserstoff-BHKWs ist
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gegenüber den Brennstoffzellen zwar geringer und durch den Carnot-Kreisprozess begrenzt, dafür ist die Technik ausgereifter und auch massiv günstiger. Der produzierte Wasserstoff kann ausserdem für die betriebseigene Fahrzeugflotte verwendet werden. Dabei können kommerzielle Brennstoffzellenfahrzeuge und Fahrzeuge mit Wasserstoffverbrennungsmotor eingesetzt werden. Im Fall der Methanisierung bietet sich auch die Nutzung des erzeugten Methans in Erdgasfahrzeugen an. Für die mobile Nutzung durch Betriebsfahrzeuge ist allerdings eine kostenintensive Implementierung von Wasserstoff- oder Erdgastankstellen notwendig. Ähnlich den erneuerbaren Energien, wird sich auch bei der Wasserstofftechnologie auf Kläranlagen, nicht nur eine einzelne spezifische Technologie durchsetzen, sondern es wird ein Zusammenspiel aus mehreren hier beschriebener Wassertechnologien stattfinden. Mit den in dieser Arbeit beschriebenen Wasserstofftechnologien ist es grundsätzlich auf Kläranlagen möglich, den Überschussstrom aus erneuerbaren Energien, in die sekundären Energieträger Wasserstoff, Biomethan und Methanol umzuwandeln. Diese Energieträger können zwischengespeichert und bedarfsgesteuert zu einem späteren Zeitpunkt wieder rückverstromt werden. Mit den hier beschriebenen Wasserstofftechnologien können Kläranlagen als Energieproduzenten, sowie als Kurz- und Langzeitspeicher fungieren. Dennoch sind diese hier beschriebenen Wasserstofftechnologien derzeit noch von finanziellen Förderungen abhängig, da ohne sie kein wirtschaftlicher Betrieb möglich wäre. Aber nicht nur Förderprogramme spielen zur Implementierung der Wasserstofftechnologie eine Rolle, sondern auch die Energierechtlichen Angelegenheiten, wie beispielsweise die Regelung im Umgang mit Nutzungsentgelten, mit der Stromsteuer und mit der EEG-Umlage.

Catalytic reforming of methane using carbon dioxide as the oxidant (Eqn. 1) is a reaction of great interest for the production of synthesis gas (H2 + CO), since in addition to generating an important chemical feedstock it simultaneously consumes two greenhouse gases. There is particular interest, as well as significant challenges, in combining it with the generation of biogas (CH4 + CO2) through the anaerobic digestion of biomass, a process that is currently significantly underutilised.
CH4 + CO2 ⇌ 2H2 + 2CO (1)
Research into the generation of electricity by direct reforming of methane using carbon dioxide in solid oxide fuel cells has been steadily increasing over the last few years, with much of the focus on using nickel supported yttria stabilised zirconia anodes [1,2]. These materials, however, suffer from severe lifetime issues due to unwanted carbon deposition caused by side reactions (Eqns. 2 and 3) and limited tolerance to sulphur that result in deactivation and limit their commercial viability. This solid formation of carbon blocks catalytically active sites and disrupts fuel distribution at the anode as well as breaking anode micro structure eventually leading to cell failure.
CH4 ⇌ C + 2H2 (2)
2CO ⇌ C + CO2 (3)
An alternative approach to using conventional nickel cermet anodes is to use mixed oxide materials. However, typically such materials show low catalytic activity and poor selectivity towards synthesis gas formation, favouring total oxidation products. In this presentation we show a novel, hydrothermally synthesized perovskite material that reforms biogas with negligible levels of carbon formation regardless of excess methane in the reactant feed. This material has significantly lower tendency to form deleterious carbon without sacrificing reforming activity and has been shown to be catalytically stable for extended periods of time (Fig.1).

Recently, the development and fabrication of electrode component of the solid oxide fuel cell (SOFC) have gained a significant importance, especially after the advent of electrode supported SOFCs. The function of the electrode involves the facilitation of fuel gas diffusion, oxidation of the fuel, transport of electrons, and transport of the byproduct of the electrochemical reaction. Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets. During the operation of a SOFC, it is necessary to avoid carburization and sulfidation problems. The present review focuses on the various aspects pertaining to a potential electrode material, the double perovskite, as an anode and cathode in the SOFC. More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed. An evaluation has been performed in terms of phase, structure, diffraction pattern, electrical conductivity, and power density. Various methods adopted to determine the quality of electrode component have been provided in detail. This review comprises the literature values to suggest possible direction for future research.

Three dimensional (3D) nano-structured crystals have received extensive attention for their superior properties over zero dimensional (0D), one dimensional (1D), or two dimensional (2D) nanomaterials in many areas. This review is generalized for the group of chalcogenide nanoflowers (NFs) by the synthetic techniques, such as solvothermal, wet chemical, sol-gel, surface oxidation, microwave, coating, electrochemical, and several other methods. The formation mechanism was also described for the purpose of opening up new food for thoughts to bring up new functionality of materials by tuning the morphology of crystals. The pH value or the template plays fundamental role in forming the nano-flowered structure. Moreover, the correlations between the surface area (SA), contact angle (CA), and the NFs are also discussed within the context. Here, we also discussed some patents relevant to the topic.

Various commercially available anode and cathode materials are investigated as the anode and cathode contact paste, respectively, for solid oxide fuel cells. In order to obtain a printable paste, chosen materials are mixed with an organic vehicle and a thinner as well as a pore former. The effect of the contact materials on the cell performance is evaluated experimentally via cell performance measurements by installing a short stack. The pastes are brush painted on the corresponding interconnector and current collecting mesh. A short stack without any contact paste is also tested for comparison as a base case. The impedance and microstructural analyses are also performed through an impedance analyzer and a scanning electron microscope, respectively. The effects of solid loading for two anode and two cathode contact paste materials which provide the best two performances during the electrochemical performance tests are also studied. After optimizing the solid loading in the anode and cathode contact paste according to the performance results, the best contact materials for each side are decided. The final short stack is then installed by using the best combination of contact pastes and then tested. The final cell shows 0.39 W cm À 2 and 0.90 W cm À 2 peak power densities at 700 1C and 800 1C, respectively, whereas the base cell provides only 0.26 W cm À 2 peak power density at 800 1C. The improvement in the cell performance is considered to be due to the enhanced contact and better current collecting by employing contact pastes.

Advances in ramjet technology over the past century have been remarkable, involving dramatic advances in flight-demonstrated technologies. The path discovery has not been without its distractions, which include world events, Initial motivation began with the will for propelling advanced aircraft, followed by missile technology, and now encouraged by the event of reusable Earth-to-orbit vehicles that employ air breathing engines for at least some of, if not the whole, flight envelope. Solid Fuel Ducted Ramjet is a propulsion technique that is used very frequently in present Air to Air missiles, by modifying the design of duct and mechanism it can available with more powerful output during lifting. The classification and the analytical study of the solid fuel ducted ramjet is given in this literature.

"The current technological status of four fuel cell technologies was reviewed, focusing on small (0.5-5kWe) stationary units suitable for domestic CHP. These were polymer electrolyte
membrane fuel cells (PEM, PEMFC, PEFC, SPFC), solid oxide fuel cells (SOFC), phosphoric acid fuel cells (PAFC), and alkaline fuel cells (AFC).

Seven categories of data were investigated that would impact on the performance of micro-CHP systems:
> Power density – power output per cm² of cell area, which determines the number of cells
(or stack area) required;
> Efficiency of the complete natural gas fuelled CHP system, at full and part load;
> Durability – the operating lifetime and rate of degradation of the fuel cell stack;
> Reliability of the system, including ancillary components;
> Current prices and estimated high-volume manufacturing costs;
> Start-up time and other dynamic constraints on power output;
> Fuel tolerance of the stack, which impacts on the required fuel processing stages."

Ba 0.50 Sr 0.50 Co 0.80 Fe 0.20 O 3-d (BSCF) presents physical, chemical and microstructural properties suitable to form the cathode of Intermediate Temperature Solid Oxide Fuel Cell (ITSOFC). This work aims the synthesis and characterization of BSCF, obtained by the citrate-EDTA method. The X-ray diffraction results indicate secondary phases for the material calcined at 700 and 800 °C and single phase with perovskite crystalline structure at 900 °C. The SEM-FEG particles micrographs show the formation of < 20 μm clusters. The dilatometric analysis of pellets indicates the sintering temperature at ~ 1050 °C. XRD results of the sintered samples show perovskite single phase. The SEM micrographs confi rmed the formation of higher porosity in the samples sintered at 1000 °C/1 h using powders calcined at 900 °C.

Dissertação apresentada como parte dos requisitos para obtenção do Grau de Mestre em Ciências na Área de Tecnologia Nuclear -Materiais. Orientadora: Profa. Dra. Emília Satoshi Miyamaru Seo SÃO PAULO 2012 Aos que buscam o caminho da Ciência, usando-a para construir o conhecimento e o saber; aos que fazem jus ao sábio pensamento crítico, contribuindo para o desenvolvimento social, científico e tecnológico.

In this study the characteristics of two different kinds of La0.6Sr0.4Co0.2Fe0.8O3‌ (LSCF) powders, one in-house powder synthesized by a co-precipitation method and another purchased from the Fuel Cell Materials Co. (FCM Co., USA) were compared. The co-precipitated powder was prepared by using ammonium carbonate as the precipitant with a NH4+/NO3- molar ratio of 2 and calcination at 1000°C for 1 h. Phase composition, morphology and particle size distribution of powders were systematically studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and laser particle size analysis (LPSA), respectively. The synthesized and commercial LSCF powders were overlaid on an Yttria-stabilized zirconia (YSZ) electrolyte having a gadolinium-doped ceria (GDC) interlayer. Electrochemical Impedance Spectroscopy (EIS) measurements were carried out at various operating temperatures in the range of 600-850°C. XRD and FESEM analysis revealed that single phase nano-crystalline LSCF powder with a mean crystallite size of 14 nm and mean particle size of 90 nm was obtained after calcination at 1000°C. The presence of hard agglomerated particles larger than a few microns in the commercial powder and also sub-micron agglomerates in the co-precipitated LSCF powder might be related to the final mechanical milling process and high calcination temperature of powders, respectively. LPSA results showed an identical mean particle size of about 1.5μm for both LSCF powders. EIS results revealed almost identical polarization resistance for both LSCF powders.

In this study, a mathematical model of an ice thermal energy storage (ITES) system for gas turbine cycle inlet air cooling is developed and thermal, economic, and environmental (emissions cost) analyses have been applied to the model. While taking into account conflicting thermodynamic and economic objective functions, a multi-objective genetic algorithm is employed to obtain the optimal design parameters of the plant. Exergetic efficiency is chosen as the thermodynamic objective while the total cost rate of the system including the capital and operational costs of the plant and the social cost of emissions, is considered as the economic objective. Performing the optimization procedure, a set of optimal solutions, called a Pareto front, is obtained. The final optimal design point is determined using TOPSIS decisionmaking method. This optimum solution results in the exergetic efficiency of 34.06% and the total cost of 28.7 million US$ y À1 . Furthermore, the results demonstrate that inlet air cooling using an ITES system leads to 11.63% and 3.59% improvement in the output power and exergetic efficiency of the plant, respectively. The extra cost associated with using the ITES system is paid back in 4.72 years with the income received from selling the augmented power.

In the present experimental work, a new synthesis method is introduced for decoration of silver on the functionalized graphene nanoplatelets (GNP-Ag) and preparation of nanofluids is reported. The thermo-physical properties, heat transfer performance and friction factor for fully developed turbulent flow of GNP-Ag/water nanofluids flowing through a circular tube at a constant heat flux were investigated. GNP-Ag uniform nanocomposite was produced from a simple chemical reaction procedure, which includes acid treatment for functionalization of GNP. The surface characterization was performed by various techniques such as XRD, FESEM, TEM and Raman. The GNP-Ag nanofluids were prepared by dispersing the nanocomposite in distilled water without the assistance of a surfactant and/or ultrasonication. The prepared nanofluids were found to be stable and no sedimentation was observed for a long time. The experimental data for GNP-Ag nanofluids were shown improvements of effective thermal conductivity and heat transfer efficiency in comparison with the corresponding to the base-fluid. The amount of enhancement was a function of temperature and weight concentration of nanoparticles. Maximum enhancement of Nusselt number was 32.7% with a penalty of 1.08 times increase in the friction factor for the weight concentration of 0.1% at a Reynolds number of 17,500 compared to distilled water. Improved empirical correlations were proposed based on the experimental data for evaluation of Nusselt number and friction factor.

"Fuel cells have the potential to reduce domestic energy bills by providing both heat and power at the point of use, generating high value electricity from a low cost fuel. However, the cost of installing the fuel cell must be sufficiently low to be recovered by the savings made over its lifetime. A computer simulation is used to estimate the savings and cost targets for fuel cell CHP systems.

Two pitfalls of this kind of simulation are addressed: the selection of representative performance figures for fuel cells, and the range of houses from which energy demand data was taken. A meta-study of the current state of the art is presented, and used with 102 house-years of demand to simulate the range of economic performance expected from four fuel cell technologies within the UK domestic CHP market.

Annual savings relative to a condensing boiler are estimated at €170–300 for a 1kWe fuel cell, giving a target cost of €350–625/kW for any fuel cell technology that can demonstrate a 2.5-year lifetime. Increasing lifetime and reducing fuel cell capacity are identified as routes to accelerated market entry.

The importance of energy demand is seen to outweigh both economic and technical performance assumptions, while manufacture cost and system lifetime are highlighted as the only significant differences between the technologies considered. SOFC are considered to have the greatest potential, but uncertainty in the assumptions used precludes any clear-cut judgement."

La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) powders were synthesized by a combination of citrate and hydrothermal methods. The thermal decomposition behavior of the as-prepared powder was carried out by simultaneous thermogravimetry–differential thermal analysis. The calcined powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and particle size distribution (PSD). Screen-printed LSCF/CGO/LSCF symmetrical cells were sintered between 1150 and 1200 °C and studied by impedance spectroscopy in order to assess the cathode kinetics for the oxygen reduction reaction. Rietveld refinement of XRD data showed the formation of a single perovskite LSCF phase with crystallite size of 53 nm at 900 °C. The best area specific resistance (ASR) value, measured in static air, was found to be 0.34 Ω cm2 at 750 °C, demonstrating that the novel citrate–hydrothermal method is an effective way to prepare cathode materials for SOFC. Cathode performance can be further enhanced by additional surface modification through impregnation with Pr-containing solution, reaching 0.17 Ω cm2 at 750 °C. Furthermore, the activation energy of the PrOx-impregnated cathode is 83.4 kJ/mol, i.e., much lower than 123.8 kJ/mol, the best value determined for PrOx-free cathodes.

Cupric oxide nanoparticles of ∼8–10 nm width and 40–45 nm length self assembled as large particles ∼1–1.5 μm have been investigated, in the 10–325 K temperature range, using magnetic and dielectric measurements. In magnetic measurements a single broad peak at ∼230 K in a zero field cooled sample has been observed. Coercivity, in magnetization measurements at 10 K, suggests that the nanoparticles are core-shell type particles with an antiferromagnetic core and a ferromagnetic shell. Dielectric measurements, at various frequencies from 3.7 Hz to 949 kHz, exhibit a sharp peak at 284 K followed by weak anomalies around 213 and 230 K.

Background: Low-income families often depend on fuels such as wood, coal, and animal dung for cooking. Such solid fuels are highly polluting and are a primary source of indoor air pollutants (IAP). We examined the association between solid fuel use (SFU) and acute respiratory infection (ARI) among under-five children in Afghanistan and the extent to which this association varies by socioeconomic status (SES) and gender. Materials and Methods: This is a cross-sectional study based on de-identified data from Afghanistan's first standard Demographic and Health Survey (DHS) conducted in 2015. The sample consists of ever-married mothers with under-five children in the household (n = 27,565). We used mixed-effect Poisson regression models with robust error variance accounting for clustering to examine the associations between SFU and ARI among under-five children after adjusting for potential confounders. We also investigated potential effect modification by SES and sex. Additional analyses were conducted using an augmented measure of the exposure to IAP accounting for both SFU and the location of cooking/kitchen (High Exposure, Moderate, and No Exposure). Results: Around 70.2% of households reported SFU, whereas the prevalence of ARI was 17.6%. The prevalence of ARI was higher in children living in households with SFU compared to children living in households with no SFU (adjusted prevalence ratio (aPR) = 1.10; 95% CI: (0.98, 1.23)). We did not observe any effect modification by SES or child sex. When using the augmented measure of exposure incorporating the kitchen's location, children highly exposed to IAP had a higher prevalence of ARI compared to unexposed children (aPR = 1.17; 95% CI: (1.03, 1.32)). SES modified this association with the strongest associations observed among children from the middle wealth quintile. Conclusion: The findings have significant policy implications and suggest that ARI risk in children may be reduced by ensuring there are clean cookstoves as well as clean fuels and acting on the socio-environmental pathways.

In this article, a novel and simple method to produce both boron doped and undoped holmia stabilized bismuth oxide nanoceramic materials has been put forward. Boron doped and undoped poly ( vinyl alcohol)/bismuth-holmia acetate nanofibers were produced using the electrospinning technique and were calcined at 850 degrees C afterward in order to obtain nanopowder. The characteristics of the nanofibers were investigated with FT-IR, XRD, and SEM. XRD analyses showed that boron undoped holmia stabilized bismuth oxide nanopowders have the face-centered cubic structure (delta-phase), and that the incorporation of boron atoms into the composite prevents the nucleus formation and turns the structure into a more amorphous glassy form. The SEM micrographs of the fibers showed that the addition of boron results in the formation of cross-linked bright-surfaced fibers. The average fiber diameters for electrospun boron doped and undoped PVA/Bi-Ho acetate nanofibers were calculated using the ImageJ software as 102 nm and 171 nm, respectively.

A typical Ce 0.85 Gd 0.15 O 2 À δ (GDC15) composition of CeO 2 À Gd 2 O 3 system is synthesized by modified sol À gel technique known as citrate-complexation. TG–DTA, XRD, FT-IR, Raman, FE-SEM/EDX and ac-impedance analysis are carried out for structural and electrical characterization. XRD pattern confirmed the well crystalline cubic fluorite structure of GDC15 after calcining at 873 K. Raman spectral bands at 463, 550 and 600 cm À 1 are also in agreement with these structural features. FE-SEM image shows well-defined grains separated from grain boundary and good densification. Ac-impedance studies reveal that GDC15 has oxide ionic conductivity similar to that reported for Ce 0.9 Gd 0.1 O 2 À δ (GDC10) and Ce 0.8 Gd 0.2 O 2 À δ (GDC20). Ionic and electronic transference numbers at 673 K are found to be 0.95 and 0.05, respectively. This indicates the possible application of GDC15 as a potential electrolyte for IT-SOFCs.

NiO-Ce 0.8 Gd 0.2 O 2 À δ (GDC) powders with controlled morphology were synthesized by a solvothermal process varying the hexamethylenetetramine (HMT) to precursor ratio. The formation of diverse morphologies as micro-flower, micro-cubes and micro-rods with different porosity were observed by varying the HMT to precursor ratio. The catalytic activity for the hydrogen oxidation reaction (HOR) and methane oxidation reaction (MOR) of the Ni-GDC anodes was studied by impedance spectra analysis using an yttria-stabilized zirconia (YSZ)-supported symmetry half-cell. Ni-GDC anode fabricated with 100HMT powder (100 wt% HMT) exhibited the least polarization resistivity of 2.59 Ω cm 2 and 26.3 Ω cm 2 measured at 750 1C under humidified H 2 and CH 4 flow, respectively. The Ni-GDC anode with better pore distribution exhibited the best electro-catalytic activity.

Scheelite type BaMoO 4 nanofibers were prepared by using acrylamide assisted sol–gel process and electrospinning technique. The prepared Scheelite Ba-MoO 4 nanofibers were characterized by using TG/DTA, XRD, FTIR, FT-Raman and SEM–EDX techniques. Thermal behavior, crystalline phase and structure of the prepared BaMoO 4 nanofibers samples were confirmed from the analysis of the obtained results of TG/DTA, XRD, FTIR and FT-Raman respectively. SEM micrographs along with EDX showed the formation of one dimensional (1D) nanofibers 100–350 nm diameters and existence of Ba, Mo and O elements in the BaMoO 4 nanofibers sample. The electrical conductivity of BaMoO 4 nanofibers as a function of temperature 200–400 °C under air was evaluated by analyzing the measured impedance data using the winfit software. The newly prepared Scheelite type BaMoO 4 nanofibers showed electrical conductivity of 0.92 9 10-3 S/cm at 400 °C.

This paper presents the detailed modeling of various components of a grid connected hybrid energy system (HES) consisting of a photovoltaic (PV) system, a solid oxide fuel cell (SOFC), an electrolyzer and a hydrogen storage tank with a power flow controller. Also, a valve controlled by the proposed controller decides how much amount of fuel is consumed by fuel cell according to the load demand. In this paper fuel cell is used instead of battery bank because fuel cell is free from pollution. The control and power management strategies are also developed. When the PV power is sufficient then it can fulfill the load demand as well as feeds the extra power to the electrolyzer. By using the electrolyzer, the hydrogen is generated from the water and stored in storage tank and this hydrogen act as a fuel to SOFC. If the availability of the power from the PV system cannot fulfill the load demand, then the fuel cell fulfills the required load demand. The SOFC takes required amount of hydrogen as fuel, which is controlled by the PID controller through a valve. Effectiveness of this technology is verified by the help of computer simulations in MATLAB/SIMULINK environment under various loading conditions and promising results are obtained. 1. INTRODUCTION Due to the considerations of environment condition, applications of renewable energy sources (RESs) are more promising; that makes environment pollution free. Also, their availability is cost free and continuous [1], [2]. Numerous RESs consist of photovoltaic system (PV), wind turbine system (WT) and micro-turbines, etc. which are considered as components of hybrid energy systems in the literature and also demonstrate applications of micro-grid [3], [4]. Due to the various seasonal and bad weather conditions such as temperature, wind speed, solar radiation and also geographical conditions, these structures are not worked properly. So, the solutions must be needed and find out. Hence, energy storage systems (ESSs) are suitable for the solution of the mitigation of wind effects, solar radiation fluctuations and also ESSs uphold the power and energy balance. Power quality also improves due to ESSs. Due to the fast variations of power, ESSs must contain a high power density as well as high energy density. So, it is required to keep more than one storage system for a hybrid energy storage system (HESS) [5]-[7]. The ESSs and battery banks (BBs) are efficiently used in hybrid energy systems (HESs). But, lifetime of batteries decreases due to the charging and discharging cycles [8], [9]. A secondary energy sources is required to enhance the supply energy reliability of HESs. Hence, a fuel cell (FC) is required to combine with the electrolyzer by giving a continuous supply to the load [10], [11]. The strategies of energy management consist of combination of PV, WT and FC comprising with electrolyzer as well as battery storage. These are most effective practice for quality of higher

The effect of Sr doping in CeO 2 for its use as solid electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce 1Àx Sr x O 2Àd (x = 0.05–0.2) are successfully synthesized by citrate-complexation method. XRD, Raman, FT-IR, FE-SEM/EDX and electrochemical impedance spectra are used for structural and electrical characterizations. The formation of well crystalline cubic fluorite structured solid solution is observed for x = 0.05 based on XRD and Raman spectra. For compositions i.e., x > 0.05, however, a secondary phase of SrCeO 3 is confirmed by the peak at 342 cm À1 in Raman spectra. Although the oxygen ion conductivity was found to decrease with increase in x, based on ac-impedance studies, conductivity of Ce 0.95 Sr 0.05 O 2Àd was found to be higher than of Ce 0.9 Gd 0.1 O 2Àd and Ce 0.8 Gd 0.2 O 2Àd. The decrease in conductivity of Ce 1Àx Sr x O 2Àd with increasing dopant concentration is ascribed to formation of impurity phase SrCeO 3 as well as the formation of neutral associated pairs, Sr 00 Ce À V ÅÅ o. The activation energies are found to be 0.77, 0.83, 0.85 and 0.90 eV for x = 0.05, 0.1, 0.15 and 0.20, respectively.

A comparative microstructural study between Ni–Ce0.9Gd0.1O1.95 (Ni–CGO) anodes obtained from NiO–CGO nanocomposite powders prepared by in situ one-step synthesis and by mechanical mixture (two-step synthesis) of NiO and CGO powders is reported. The open porosity and microstructure of sintered and reduced pellets were investigated as a function of the citric acid content used as pore forming agent. Nanosized crystallites for the one-step and two-step routes were around 18 nm and 24 nm against 16 nm and 37 nm, for CGO and NiO, respectively. Overall results show that both routes provided suitable microstructures either for anode-support, or for functional anodes for solid oxide fuel cells (SOFCs), with more versatile characteristics in the case of the one-step route. The electrical characterization of selected NiO–CGO samples, carried out between 90 and 260 °C by impedance spectroscopy, confirms electrical percolation of both phases in the composites. However, based on combined microstructural and impedance data, it seems clear that the one-step processing route is the best approach to make SOFC anodes with improved performance.

This paper presents a full and partial load exergy analysis of a hybrid SOFC–GT power plant. The plant basically consists of: an air compressor, a fuel compressor, several heat exchangers, a radial gas turbine, mixers, a catalytic burner, an internal reforming tubular solid oxide fuel cell stack, bypass valves, an electrical generator and an inverter. The model is accurately described. Special attention is paid at the calculation of SOFC overpotentials. Maps are introduced, and properly scaled, in order to evaluate the partial load performance of turbomachineries. The plant is simulated at full-load and part-load operation, showing energy and exergy flows trough all its components and thermodynamic properties at each key-point. At full-load operation a maximum value of 65.4% of electrical efficiency is achieved. Three different part-load strategies are introduced. The off-design operation is achieved handling the following parameters: air mass flow rate, fuel mass flow rate, combustor bypass, gas turbine bypass, avoiding the use of a variable speed control system. Results showed that the most efficient part-load strategy corresponded to a constant value of the fuel to air ratio. On the other hand, a lower value of net electrical power (34% of nominal load) could be achieved reducing fuel flow rate, at constant air flow rate. This strategy produces an electrical efficiency drop that becomes 45%.

Ceria has higher conductivity than the conventional SOFC electrolyte, yttria-stabilized zirconia (YZS) but has the drawback of measurable electronic conductivity, particularly at high temperatures. The aims of this work research are to synthesize several Gd and Er co-doped ceria materials as solid electrolyte for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) and to obtain the correlation between the average ionic radius of dopants and the value of their conductivity. Three set material have been choosen as target of this research. They are Ce 1-x-y Gd x Er y O 2-z (CeGdEr); Ce 1-x-y Gd x Dy y O 2-z (CeGdDy); and Ce 1-x-y Gd x Nd y O 2-z (CeGdNd). In this paper, one set material of CeGdEr have been synthesized, they are Ce90Gd5Er5, Ce85Gd5Er10, Ce85Gd10Er5, and Ce80Gd10Er10. Their structures have been investigated using X-Ray Diffraction (XRD) and refined it using Le Bail method. All material have the similar structure that is cubic structure with space group Fm3m, but only a little differences at their lattice parameter. The lattice parameter for Ce90Gd5Er5, Ce85Gd5Er10, Ce85Gd10Er5, and Ce80Gd10Er10 are 5,406(9) Å; 5,434(1) Å; 5,434(1) Å; and 5,430(2) Å, respectively. Moreover, Ce90Gd5rEr5 morphology have been investigated using Scanning Electron Microscope (SEM). The result is Ce90G5Er5 still has pore probably due to the low temperature of sintering. The result of EDS characterization show that there is no impurity in Ce90Gd5Er5 material.

Atomic scale computer simulations, validated with experimental data, are used to uncover the factors responsible for defect-induced chemical expansion observed in non-stoichiometric oxides, exemplified by CeO2 and ZrO2. It is found that chemical expansion is the result of two competing processes: the formation of a vacancy (leading to a lattice contraction primarily due to electrostatic interactions) and the cation radius change (leading to a lattice expansion primarily due to steric effects). The chemical expansion coefficient is modeled as the summation of two terms that are proportional to the cation and oxygen radius change. This model introduces an empirical parameter, the vacancy radius, which can be reliably predicted from computer simulations, as well as from experimental data. This model is used to predict material compositions that minimize chemical expansion in fluorite structured solid oxide fuel cell electrolyte materials under typical operating conditions.

In recent days, the development of low-cost, sustainable, efficient electrode materials for energy storage applications is of great interest. Herewith, Cudoped Ca(Ti 0.9 Fe 0.1)O 3-d (Cu:CTF) double-perovskite electroceramic, heat-treated at diverse temperatures (800-1100°C) were prepared using sol-gel technology. X-ray diffraction pattern confirmed the orthorhombic structure of the prepared Cu:CTF perovskites. Significant traces of TiO 2 , CuO vanishes at elevated temperatures, which is evident from the XRD pattern. Further, the secondary phase traces were also observed in XRD, but without changing its crystal structure of Cu:CTF nanotitanate. The crystalline nature of the Cu:CTF ceramic was identified around 750°C employing TG/DTA. UV-visible spectroscopy demonstrates the poor visible absorbance region towards the red shift with the bandgap variation of 5.28-5.42 eV. The nature of the Cu:CTF particles were analyzed using electron microscopes with the estimated particle size between 52 and 190 nm. Considering the action of temperature and frequency, complex impedance spectroscopy was utilized to analyse the inter-and intra-grain inclusions. Complex impedance spectroscopy study confirms the existence of dipole-dipole relaxation and Maxwell-Wagner (MW) polarisation for the samples heated above 900°C. However, the a.c. test reveals the presence of conduction due to the addition of Cu 2? ions to CaTi 1-x Fe x O 3-d perovskite, which enhances oxygen vacancies and is strongly dependent on the inhibition of the hopping conduction mechanism.

The CeO2-based electrolyte low temperature SOFCs require special electrodes with a higher performance and compatibility. The performance of the CeO2-based composite anodes depends on microstructural features such as particle size, tripe phase boundaries (TPB), surface area, and percolation. Some of the primary parameter can be manipulated during the materials synthesis. In this work the compound NiO–Ce0.9Gd0.1O1.95 (NiO–CGO), used as anode in SOFC, was synthesized by two different processes. Both of them are based on the polymeric precursor method. Characterized by simultaneous thermogravimetry-differential thermal analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and dilatometry. The refinement of the XRD data indicated that the composite sample synthesized by the process called “one step synthesis” produced smaller crystallite size in comparison to the sample attained by the two steps process. Simple preliminary performance tests were done with single cells in which such I–V curves indicated that the cell with one step anode had better performance. “One step synthesis” product, in situ nanocomposite, presented similar fine grained particle sizes for both phases Ni and CGO, which would be beneficial to the electrochemical activity, also indicated by first performance tests.

A comparative microstructural study between Ni-Ce 0.9 Gd 0.1 O 1.95 (Ni-CGO) anodes obtained from NiO-CGO nanocomposite powders prepared by in situ one-step synthesis and by mechanical mixture (two-step synthesis) of NiO and CGO powders is reported. The open porosity and microstructure of sintered and reduced pellets were investigated as a function of the citric acid content used as pore forming agent. Nanosized crystallites for the one-step and two-step routes were around 18 nm and 24 nm against 16 nm and 37 nm, for CGO and NiO, respectively. Overall results show that both routes provided suitable microstructures either for anode-support, or for functional anodes for solid oxide fuel cells (SOFCs), with more versatile characteristics in the case of the one-step route. The electrical characterization of selected NiO-CGO samples, carried out between 90 and 260 1C by impedance spectroscopy, confirms electrical percolation of both phases in the composites. However, based on combined microstructural and impedance data, it seems clear that the one-step processing route is the best approach to make SOFC anodes with improved performance.

"Fuel cells already provide heat and power to people’s homes with lower direct CO2 emissions and fuel consumption than traditional methods. However, their whole life cycle, including manufacture and disposal, must be considered to verify that these environmental impacts are actually reduced and not merely shifted elsewhere. The total carbon footprint and energy payback times have been widely reported for other emerging microgeneration technologies, but have not previously been calculated for fuel cell systems.

This paper presents a life cycle assessment comparing solid oxide fuel cell (SOFC) based domestic CHP with the current embedded technologies in the UK. An inventory is given for the construction of a 1 kW stack and then its operation is simulated in detail using measured energy demands from hundreds of UK houses. Producing a 1 kW planar SOFC micro-CHP system was estimated to require 12–17 GJ of energy input and emit 700–950 kg of CO2, although these impacts triple when including the production of replacement stacks needed over the 10 year system life.

The carbon intensity of electricity generation from an SOFC was estimated to be 325–375 g/kWh, and is primarily determined by the operating efficiency as manufacturing only adds 10% to this. By displacing electricity generation in less efficient centralised power stations, operating an SOFC in UK homes would reclaim the energy and carbon from its manufacture in under 2 years; however, payback may not be possible if only high efficiency CCGT units are displaced."

A modified sol–gel method which is also known as citrate complexation is used here to prepare Ce 0.8 Ln 0.2 O 2Àd (Ln = Y 3+ , Gd 3+ , Sm 3+ , Nd 3+ and La 3+) solid solutions for their proposed application in intermediate-temperature solid oxide fuel cells (IT-SOFCs) as electrolytes. All the samples exhibit the fluorite type crystalline structure without any phase segregation, characteristics of CeO 2 , as revealed in XRD pattern. The lattice parameters and densities calculated based on the oxygen vacancy model agreed well with the experimental (Archimedes method) values. The formation of solid solution is also confirmed by Raman spectroscopy. The microstructural features of the samples are recorded by using FE-SEM/TEM. The ionic conductivities of various Ln-doped samples at 623 K as obtained from electrochemical impedance measurement are as follows: Ce 0.8 Sm 0.2 O 2Àd > Ce 0.8 Gd 0.2 O 2Àd > Ce 0.8 Nd 0.2 O 2Àd > Ce 0.8 La 0.2 O 2Àd > Ce 0.8 Y 0.2 O 2Àd. The activation energy for total conductivity are found to be 0.86, 0.87, 0.89, 0.96 and 1.02 eV for Sm, Gd, Nd, La and Y doped ceria, respectively. The relationship between the dopant radius, chemical composition , lattice parameters, morphology and electric properties are discussed here.

Electrolysis Synthetic fuel Co-electrolysis a b s t r a c t Electrolysis of steam and co-electrolysis of steam and carbon dioxide was studied in Solid Oxide Electrolysis Cell (SOEC) stacks composed of Ni/YSZ electrode supported SOECs. The results of this study show that long-term electrolysis is feasible without notable degradation in these SOEC stacks. The degradation of the electrolysis cells was found to be influenced by the adsorption of impurities from the applied inlet gases, whereas the application of chromium containing interconnect plates and glass sealings do not seem to influence the durability when operated at 850 C. Cleaning the inlet gases to the Ni/YSZ electrode resulted in operation without long-term degradation, and may therefore be a solution for operating these Ni/YSZ based SOEC stacks without degradation. (S.D. Ebbesen).

Solid oxide fuel cells (SOFC) are the current research having several potential to obtain high efficiency, high energy-density power generation which operated at relatively higher temperature. Yttrium oxide (Y 2 O 3 ) contributions at high temperature are accelerating to the development oxide layer of FeCr alloy. The aim of this research is to investigate the microstructure of Fe/Cr added with Y 2 O 3 acting as a reactive element. The purpose is to improve macrostructure of Fe/Cr powders which can be applied at steel industry. In this study the mixing process of Fe/Cr and Y 2 O 3 powder was conducted via ultrasonic treatment at a frequency of 22 kHz, and at two different holding time of 2.5 h and 3.5 h. The particle size of chromium (Cr) can be reduced by ultrasonic treatment at from 60µm to 30µm through threshing the cluster of Cr particle. It shows that the ultrasonic vibration effectively removes oxides and other contaminates on a surface coating. Therefore, homogeneity of the parent material, segregation, and uniform distribution of second phase were increased.

In this study, the synthesis of Ce 0.8 Sm 0.2 O 1.9 (SDC) solid electrolyte by the ultrasound assisted co-precipitation method was accomplished to explore the effects of ultrasound power, ultrasound pulse ratio and probe type upon the ionic conductivity of SDC as well as the lattice parameter, the microstructure and the density. Fine powders of uniform crystallite sizes (average 11.70 ± 0.62 nm) were obtained, needing lower sintering temperature. The SDC powders were successfully sintered to a relative density of over 95% at 1200 °C (5 °C min À1) for 6 h. The micrograph of SDC pellets showed non-agglomerated and well-developed grains with average size of about 200 nm. X-ray diffraction analysis showed that the lattice parameter increased with increasing acoustic intensity and reached a maximum for the 14.94 W cm À2. Further, a linear relationship was detected between the lattice parameter and the ionic conductivity, inspiring a dopant like effect of US on the electrolyte properties. The highest ionic conductivity as r 800°C = 3.07 Â 10 À2 S cm À1 with an activation energy E a = 0.871 kJ mol À1 was obtained with pulsed ultrasound for an acoustic intensity of 14.94 W cm À2 , using 19 mm probe and 8:2 pulse ratio.

Although tremendous progress in the last years has resulted in high power densities and the ability to use hydrocarbons as a fuel, solid oxide fuel cells still remain less developed than other fuel cell types . The difference in maturity is mainly related to the need to investigate and understand SOFC processes under technically relevant operating conditions, namely high fuel utilization and the associated inhomogeneous current density and temperature distributions. Under these exacerbated operating conditions, durability of cells and stacks is reduced and degradation mechanisms are significantly distinct compared to idealized operation. Due to the electrochemical reaction, gradients of the reactant and product composition can be observed along the flow path of the gases. Especially high fuel utilization leads to a depletion of the fuel along the flow path and to varying power densities. Furthermore, the electrochemical reaction is associated with heat production, resulting in temperature gradients in such a system. To optimize cells for operation in highly efficient systems a new measurement system is needed that allows the determination of local effects and the identification of critical operation parameters. Segmented cell components for measuring distribution of temperature and current density have been used successfully in polymer electrolyte fuel cells (PEFC) . Recently, a similar approach has been used for the investigation of SOFC. However, the experimental challenges are higher in the case of high-temperature fuel cells since all segments have to be contacted reliably and homogenously at 800 °C . Nevertheless, the spatial resolution that is incorporated in the developed system allows the identification of possible steep gradients along the flow path. As a result this measuring tool represents an important methodological addition for the optimization of fuel cell operation and for the optimization of stack and cell designs.

The effect of Gd doping on the ionic conductivity of CeO 2 for its use as a solid electrolyte material for the intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce 1Àx Gd x O 2Àd (x = 0.1– 0.3) samples are successfully synthesized by carbonate co-precipitation method. XRD, FT-IR, Raman spec-troscopy, UV–Vis spectroscopy, SEM and impedance spectroscopy are used for structural and electrical characterization. From the XRD patterns, well-crystallite cubic fluorite structured solid solution is confirmed. As Gd 3+ ions are doped into CeO 2 lattice, the absorption spectrum exhibits a red shift when compared to CeO 2. Raman spectra show a peaks at 463 cm À1 , 546 and 600 cm À1 , which are the characteristic peaks of doped ceria. Based on ac-impedance data, the total ionic conductivity is same for both Ce 0.9 Gd 0.1-O 2–d (GDC10) and Ce 0.8 Gd 0.2 O 2–d (GDC20) in the temperature range 473 K–623 K. Hence for Gd doped ceria solutions 10% and 20% of Gd, are proper doping level which leads to the maximum total conductivity. Above this doping level, the mobility of oxygen ions decreases the total conductivity due to blocking effect.

A detailed knowledge about the microstructure and morphology of anode structure is compulsory to develop an efficient solid oxide fuel cell (SOFC) system with excellent performance for generating electricity. A porous ceramic anode with controlled microstructure is determined by its available surface area for reaction and the ability of reactants to reach the reaction. This can be achieved by adding pore former into the anode suspension. In this study, flat sheets of nickel oxide-yttria stabilized zirconia (NiO-YSZ) anode cermet with the mixture of 0-10 wt % of the pore forming agent (i.e. polyether ether-ketone, PEEK) were cast using combined phase-inversion technique and then undergone sintering process at 1450 °C. In the end of the study, the results were compared to the original anode sample without pore former. The addition of PEEK as pore former into NiO-YSZ suspension yields a significant change to the viscosity of anode suspension. Besides that, the effect of pore former loading on porosity and mechanical strength were investigated to assess their suitability for use as anode substrates. The sintered anodes were also characterized using Scanning electron microscopy (SEM) and x-ray diffraction (XRD) to verify and evaluate the effectiveness of each potential pore former powder. Detailed study demonstrated that the pore-former has a major influence on the pore structure of anode creating a desired macrostructure with adequate mechanical strength, and porosity for better performance of planar SOFC system.

In the present study, a phase field method is used to simulate the morphological and crystal structural evolution of nickel-yttria stabilized zirconia composite anode of solid oxide fuel cell based on three-dimensional microstructures reconstructed by focused ion beam-scanning-electron-microscopy technique. A three-dimensional reconstruction of the anode sample after initial reduction is used as the initial microstructure. In order to simulate the nickel crystal grain growth and the corresponding morphological change at the same time, both material composition and crystallographic orientation order parameters are introduced in the model. In order to quantitatively study the nickel coarsening effect on anode performance, the evolution of three-phase boundary density and nickel specific surface area are quantitatively calculated in the simulations. Simulation results reproduced well the initial microstructural evolution in the experiments.

We have investigated the comparable performance of raw and ash-free coal in the operation of a direct carbon fuel cell (DCFC). The various structural and morphological analyses using SEM, TEM, EDX, XPS, XRD, and TGA are carried out to study the distinct physicochemical properties of coals. Due to contained volatile organic compounds, raw coal generates about a two-fold higher fuel cell performance compare to ash-free coal below a reaction temperature of 750 • C. However, over a cell temperature of 900 • C, both of them reach a similar power density of 170 mW cm −2 . In the long-term operation of a DCFC, we observe a distinctly more durable power performance using ash-free coal than that of raw coal.