This project proposes a solar-driven hybrid system for electricity generation and hydrogen production, which includes concentrated solar power (CSP), photovoltaic (PV), solid oxide electrolyser (SOEC). Electricity from the CSP and PV provides a continuous 24/7 supply to meet demand-side power consumption. When demand-side power consumption is low, the excess power is used to electrolyse water in the SOEC system. In this study, an SOEC is modelled, operation strategy for the solar-driven hybrid system is developed, the techno-economic performance of the overall system is evaluated, and sensitivity analysis is performed. For the modelling part, first develop an SOEC component in Matlab and Trnsys by considering the electrochemical model, thermal model and electric model. Second, design the hybrid system layout and simulate the system under 8760 hours in Matlab and Trnsys. The hybrid system is divided into five blocks: Heat Energy Source Block, Thermal Energy Storage Block, Rankine Cycle Block, Photovoltaic Block, Power to Hydrogen (PtH) Block. The operation strategy is: the heat is collected using a tower solar receiver and stored in tanks by heat transfer fluid molten salt. These thermal energy heats the water in heat exchangers and the resulting high temperature water vapour is used in steam turbine to generate electricity; at the same time part of the heat transfer fluid heats the feedwater in the PtH block and the resulting high temperature water vapour is used in SOEC for hydrogen production, if the operation temperature of steam in SOEC is not reached after heat exchange, the electric heater will heat the steam to raise the temperature. The CSP and PV provide electricity to demand side and SOEC. The produced hydrogen will be transported by truck or ship after compressed. For results part, the minimum CSP configurations to provide a 24/7 demand-side electricity consumption is a solar multiple (SM) with 2 and thermal storage (TES) size of 14 hours. SOEC stack has the best techno-economic performance at a nominal power of 275 Watt. The hybrid system has a levelised cost of electricity (LCOE) at 0.219 USD/kWh and a levelised cost of hydrogen (LCOH) at 7.5 USD/Kg. There are several sensitivity parameters for increase the energy productivity and decrease levelised cost. The larger the SM, the better the ability to generate power. The larger the TES size, the more the hourly generation is similar, otherwise it will fluctuate more. Increasing the SM results in a higher LCOE and a significantly lower LCOH. Increasing TES size also increases the LCOE, whereas the TES size has a marginal impact on the decrease of LCOH. Increased installed capacity inevitably leads to increased power generation. The increasing total power capacity makes the surplus power at the same demand side increase, so the SOEC runs at higher input power and the total hydrogen production increases, resulting in a lower LCOH. The effect of SOEC capacity on LCOH depends on the relationship between input power and SOEC nominal power. Higher operation temperature of SOEC leads to the lower the reversible voltage and an increasing consumption for water vapour. However, when the water vapour concentration is too high, the electrolysis current will instead drop, meaning that the rate of hydrogen production will drop.

No description available.

Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy and have the potential to become a reliable renewable energy source that can be used on a large scale. SOFCs have 3 main components; the electrolyte, the anode, and the cathode. Typically, SOFCs work by reducing oxygen at the cathode into O2- ions which are then transported via the electrolyte to the anode to combine with a fuel such as hydrogen to produce electricity. Research into better materials and manufacturing methods is necessary to reduce costs and improve efficiency to make the technology commercially viable. The goal of the research is to optimize and simplify the production of single SOFCs using high performance ceramics. This includes the use of 8mol% Y2O3-ZrO2 (YSZ) and 10mol% Sc2O3-1mol%CeO2-ZrO2 (SCSZ) layered electrolytes which purport higher conductivity than traditional pure YSZ electrolytes. Prior to printing the electrodes onto the electrolyte, the cathode side of the electrolyte was coated with 20mol% Gd2O3-CeO2 (GDC). The GDC coating prevents the formation of a nonconductive La2Zr2O7 pyrochlore layer, which forms due to the interdiffusion of the YSZ electrolyte ceramic and the (La0.6Sr0.4)0.995Fe0.8Co0.2O3 (LSCF) cathode ceramic during sintering. The GDC layer was deposited by spin coating a suspension of 10wt% GDC in ethanol onto the electrolyte. Variation of parameters such as time, speed, and ramp rate were tested. Deposition of the electrodes onto the electrolyte surface was done by screen printing. Ink was produced using a three roll mill from a mixture of ceramic electrode powder, terpineol, and a pore former. The pore former was selected based on its ability to form a uniform well-connected pore matrix within the anode samples that were pressed and sintered. Ink iii development involved the production of different ratios of powder-to-terpineol inks to vary the viscosity. The different inks were used to print electrodes onto the electrolytes to gauge print quality and consistency. Cells were produced with varying numbers of layers of prints to achieve a desirable thickness. Finally, the densification behaviors of the major materials used to produce the single cells were studied to determine the temperatures at which each component needs to be sintered to achieve the desired density and to determine the order of electrode application, so as to avoid over-densification of the electrodes. Complete cells were tested at the National Energy Technology Laboratory in Morgantown, WV. Cells were tested in a custom-built test stand under constant voltage at 800°C with 3% humidified hydrogen as the fuel. Both voltage-current response and impedance spectroscopy tests were conducted after initial startup and after 20 hours of operation. Impedance tests were performed at open circuit voltage and under varying loads in order to analyze the sources of resistance within the cell. A general increase in impedance was found after the 20h operation. Scanning electron micrographs of the cell microstructures found delamination and other defects which reduce performance. Suggestions for eradicating these issues and improving performance have been made.

<p>Long-term stability and chromium (Cr) contamination are two major concerns for application of chromium-bearing metallic materials as interconnects of solid oxide fuel cells (SOFCs) at intermediate temperature (~800°C). Copper-manganese (Cu-Mn) and cobalt-manganese (Co-Mn) spinel can be promising coating materials for the metallic interconnects as they show high electrical conductivities. The first objective of this research is to develop an economical and convenient method through which the spinel coatings can be applied to the metallic substrates. The investigations on the crystal structure of CuᵪMn₃₋ᵪO₄ spinel, e.g., structure symmetry and cation distributions, have always been controversial, which hinders the total understanding of the detailed structure of the material. In order to resolve the inconsistency, in-situ neutron and X-ray diffraction were employed to determine the structure of the spinel.</p> <p>A novel method was developed to obtain high quality manganese coating without any additives (sulphur or selenium compounds). Cu-Mn and Co-Mn spinel coatings were applied to metallic coupons by electrodeposition and subsequent annealing. The method is convenient and easy to control. The performance testing showed that the area specific resistances (ASRs) of the coated samples (0.003 Ω•cm²) are much lower than that of the uncoated UNS 430 (0.189 Ω•cm²) after oxidation at 750°C for 1500 hours. Moreover, both spinel coatings can effectively suppress the outward diffusion of Cr, which resulted in reduction of Cr contamination significantly. The oxidation studies of Cu-Mn coating revealed the transformation mechanisms of Cu-Mn coating to the spinel. In-situ neutron and X-ray diffraction analysis clarified the crystal symmetry of CuᵪMn₃₋ᵪO₄ spinel and CuMnO₂ at high temperatures. Rietveld refinement revealed the cation distribution of Cu and Mn ions on tetrahedral and octrahedral sites of CuᵪMn₃₋ᵪO₄ spinel, which was compared to values in the literatures. / Thesis / Doctor of Philosophy (PhD)

No description available.

The application of the entropy concept to stabilize oxide systems opens the possibility of discovering new materials with unique structural and functional properties. High-entropy alloys and oxides, which are based on the entropy stabilization concept and composed of multi-principal elements, have the potential to tailor structural and functional properties to meet specific needs. The study of lanthanum-based perovskite materials that benefit from the entropy stabilization approach is a promising area of research.However, the inherent randomness of multi-principal elements presents new challenges, making it difficult to predict their behavior. To understand these difficulties, we have initiated a methodical investigation of La-based medium- and high-entropy perovskite oxides. This study focuses on the synthesis, characterization, sintering mechanism, and electrical conductivity properties of nine La1-xCax(A1/3, B1/3, C1/3)O3 medium-entropy perovskite oxide systems (A, B, and C = three combination of Cr or Co or Fe or Ni or Mn) and one La1-xCax(Cr0.2Co0.2Fe0.2Ni0.2Mn0.2)O3 high-entropy perovskite oxide system (for x = 0.1 to 0.3). This research aims to provide better understanding of: (1) synthesis process, (2) temperature of single-phase formation, (3) the impact of various combinations of multiple B-site transitional elements and Ca doping on crystal structure, and microstructure (4) sintering mechanism and (5) electrical conductivity properties.

No description available.

No description available.

No description available.

No description available.