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Internal partial oxidation reforming of butane and steam reforming of ethanol were investigated using microtubular solid oxide fuel cells (SOFCs) supported on nickel-gadolinia doped ceria (Ni-GDC) anodes for portable power sources in emergency situations and for mobilities, such as vehicles, robots and drones. At an oxygen/carbon (O/C) ratio of 1.0, which is a coking condition in the equilibrium, the Ni-GDC anode deteriorated for 28 h by internal partial oxidation of butane at 650 °C. However, power generation was also impossible after 8 h and 79 h at steam/carbon (S/C) = 1.0 and 1.5, respectively, by internal steam reforming of ethanol despite of no carbon deposition condition in the equilibrium at 650 °C. Power can be generated for more than 100 h at O/C = 1.5 in butane and at S/C = 2.0 in ethanol. For internal partial oxidation reforming of methane and steam reforming of ethanol in SOFCs, the O/C and S/C ratios are significantly important to prevent carbon deposition on the Ni-GDC anode. [ABSTRACT FROM AUTHOR]

Here, we report a chip-type module [size: 0.3 X I X 3 cm (∼ 1 cm³) + fuel manifold] using micro-solid oxide fuel cell (SOFC) bundles which consist of anode-supported microtubular SOFCs with 2 mm diameter, porous cathode matrices, sealing layers, and interconnects. The module is a three-bundle stack with fuel manifolds and is designed to apply to small-sized power sources. The performance of the module was shown to be 2.85-2.6 V open-circuit voltage, with maximum power outputs of 0.91, 1.54, and 1.79 W at 450, 500, and 550°C operating temperatures, respectively, where the air was applied only by natural convection. An increase of the fuel flow rate effectively improved the performance of the module due to an improvement of the gas transport process. The fuel utilization of the module was also estimated for the optimization of the module operating conditions, which was strongly influenced by the fuel flow rates and the operating temperatures. [ABSTRACT FROM AUTHOR]

In this study, we fabricated an anode-supported microtubular solid oxide fuel cell (SOFC) with the cell configuration La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)-Ce0.8Gd0.2O1.9 (CGO) cathode/CGO buffer layer/(ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (ScSZ) electrolyte/Ni-ScSZ anode. A power generation test of the SOFC was carried out at 0.1-0.7 MPa at 650°C. By using a wet H2-N2 gas mixture and air, the maximum power density of the microtubular cell was found to be 0.68 W cm-2 (at 2.6 A cm-2, Uf = 78%) at atmospheric pressure (0.1 MPa). With increasing the operating pressure, the performance of the cell was improved, and the power density reached 1.48 W cm-2 (at 2.8 A cm-2, (Uf = 86%). It was confirmed by the current interruption method that both polarization and ohmic resistances decrease under a pressurized condition. [ABSTRACT FROM AUTHOR]

The article discusses the modeling, mechanical, and electrochemical properties of micro-tubular Solid Oxide Fuel Cells (SOFCs) and SOFC cube stacks. An elaboration of the applicability of the micro-tubular SOFC and the fabricated cube-type cell sack module for commercialization of an auxiliary power unit and a stationary small power source system is presented. The author also describes the micro-tubular SOFCs with high energy efficiency, quick on and off performance, and low production cost.

Abstract: Steam electrolysis was carried out using a microtubular ceramic reactor with the following cell configuration: La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)–Ce0.8Gd0.2O1.9 (CGO) electrode/CGO buffer layer/(ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (ScSZ) electrolyte/Ni-ScSZ electrode supporting tube. 10% H2/Ar gas was used as steam carrier gas, and 18% steam was supplied to the ceramic reactors. The cell performance was as follows: 1.43V at 0.1Acm−2 and 650°C (Area specific resistance: 4.7Ωcm2) or 1.37V at 0.1Acm−2 and 700°C (4.3Ωcm2). During steam electrolysis, hydrogen production proportionally increased with current density according to Faraday''s law, and heat generation at a low current density was observed by an electrochemical technique. Voids and Zr diffusion from the ScSZ electrolyte were confirmed in the CGO buffer layer. Such factors near the surface probably influenced the increase in ohmic loss and electrode polarization. [Copyright &y& Elsevier]

Abstract: In this study, new temperature monitoring method for solid oxide fuel cells (SOFCs) was proposed, and the demonstration using micro-tubular SOFCs has done. The fabricated micro-tubular SOFCs were operated under the two different conditions, and polarization during the power generation was measured. The cell resistance as a function temperature was also measured. Based on the temperature dependence of cell resistance and the measured ohmic drop during the power generation, the cell temperature was estimated. The estimated cell temperature clearly depended on operation condition and increased with increasing of the current density. The estimated cell temperature was also in nearly proportion to the temperature which was measured by a thermocouple, and it was conformed that this temperature monitoring method by electrochemical technique certainly functioned. [Copyright &y& Elsevier]

Abstract: Realization of micro tubular solid oxide fuel cell (SOFC) modules, which are robust and low temperature operable, is expected to accelerate the commercialization of SOFC systems. “Advanced ceramic reactor” project targets on realizing such a high-efficient micro ceramic reactor, especially a novel SOFC module. The goal of this research/development project is to develop electrode and electrolyte materials for low temperature operation, and to establish manufacturing process technology for micro tubular SOFCs and integrated modules, as well as demonstration of cell stack modules. In this paper, the concept of advanced ceramic reactor project and recent achievement will be presented. [Copyright &y& Elsevier]