High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

A hydrogen-oxygen regenerative fuel cell (RFC) energy storage system based on high temperature solid oxide fuel cell (SOFC) technology is described. The reactants are stored as gases in lightweight insulated pressure vessels. The product water is stored as a liquid in saturated equilibrium with the fuel gas. The system functions as a secondary battery and is applicable to darkside energy storage for solar photovoltaics

Performance of an Anode Supported Solid Oxide Fuel Cell with Indirect Internal Reforming

The conversion of fuel into hydrogen-rich gas is necessary for fuel cells. This can be achieved either indirectly in fuel processing systems, in which the hydrocarbon feed is converted in an external catalytic steam reformer, or directly in the fuel cell. In this paper, the unit module of solid oxide fuel cell was assembled by one reformer and four cells. The reformer was fabricated by extruded dummy cell and combined with two cells on each side respectively. The reforming catalyst was coated on internal channel of the dummy cell. The unit module has successfully tested with wet CH4 as fuel and air as oxidant and its maximum power density exceeded 150mW/cm(2) at 750 degrees C.open110Nsciescopu

Apparatus for Operando X-ray Diffraction of Fuel Electrodes in High Temperature Solid State Electrochemical Cells

Characterizing electrochemical energy conversion devices during operation is an important strategy for correlating device performance with the properties of cell materials under real operating conditions. While operando characterization has been used extensively for low temperature electrochemical cells, these techniques remain challenging for solid oxide electrochemical cells due to the high temperatures and reactive gas atmospheres these cells require. Operando X-ray diffraction measurements of solid oxide electrochemical cells could detect changes in the crystal structure of the cell materials, which can be useful for understanding degradation process that limit device lifetimes, but the experimental capability to perform operando X-ray diffraction on the fuel electrodes of these cells has not been demonstrated. Here we present the first experimental apparatus capable of performing X-ray diffraction measurements on the fuel electrodes of high temperature solid oxide electrochemical cells during operation under reducing gas atmospheres. We present data from an example experiment with a model solid oxide cell to demonstrate that this apparatus can collect X-ray diffraction spectra during electrochemical cell operation at high temperatures in humidified H2 gas. Measurements performed using this apparatus can reveal new insights about solid oxide fuel cell and solid oxide electrolyzer cell degradation mechanisms to enable the design of durable, high performance devices.Comment: 17 page

A Two-Dimensional Model of a Single-Chamber SOFC with Hydrocarbon Fuels

The single chamber fuel cell (SCFC) is a novel simplification of the conventional solid oxide fuel cell (SOFC) into which a premixed fuel/air mixture is introduced. It relies on the selectivity of the anode and cathode catalysts to generate a chemical potential gradient across the cell. For SCFC running on hydrocarbon fuels, the anode catalyst promotes in-situ internal reforming of the hydrocarbon and electrochemical oxidation of the syngas, while the cathode catalyst reduces oxygen simultaneously. Laboratory tests of small designs of such fuel cells have demonstrated excellent electrical performance (1, 2)

New fuel cell electrodes made from graphene nanosheets and their nanocomposites

The production of novel catalyst support materials could open up new ways to enhance the catalytic activity by reduced catalyst loadings. Nanocomposites composed of conducting polymers reinforced with graphene nanosheets (GNS) or graphite oxide (GO) sheets can be potential fuel cell electrodes as an alternative to commercial fuel cell electrodes

Infiltrated La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3 based anodes for all ceramic and metal supported solid oxide fuel cells

Financial support by the EU project METSAPP (FP7-278257) and Energinet.dk under the project ForskEL 2012-1-10806 is gratefully acknowledged.For improved robustness, durability and to avoid severe processing challenges alternatives to the Ni:YSZ composite electrode is highly desirable. The Ni:YSZ composite electrode is conventionally used for solid oxide fuel cell and solid oxide electrolysis cell. In the present study we report on high performing nanostructured Ni:CGO electrocatalyst coated A site deficient Lanthanum doped Strontium Titanate (La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3) based anodes. The anodes were incorporated into the co-sintered DTU metal supported solid oxide fuel cell design and large sized 12 cm × 12 cm cells were fabricated. The titanate material showed good processing characteristics and surface wetting properties towards the Ni:CGO electrocatalyst coating. The cell performances were evaluated on single cell level (active area 16 cm2) and a power density at 0.7 V and 700 °C of 0.650 Wcm−2 with a fuel utilization of 31% was achieved. Taking the temperature into account the performances of the studied anodes are among the best reported for redox stable and corrosion resistant alternatives to the conventional Ni:YSZ composite solid oxide cell electrode.Publisher PDFPeer reviewe

Jet fuel based high pressure solid oxide fuel cell system

A power system for an aircraft includes a solid oxide fuel cell system which generates electric power for the aircraft and an exhaust stream; and a heat exchanger for transferring heat from the exhaust stream of the solid oxide fuel cell to a heat requiring system or component of the aircraft. The heat can be transferred to fuel for the primary engine of the aircraft. Further, the same fuel can be used to power both the primary engine and the SOFC. A heat exchanger is positioned to cool reformate before feeding to the fuel cell. SOFC exhaust is treated and used as inerting gas. Finally, oxidant to the SOFC can be obtained from the aircraft cabin, or exterior, or both

Monolithic Solid Oxide Fuel Cell development

The Monolithic Solid Oxide Fuel Cell (MSOFC) is an oxide-ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/L, at fuel efficienceis over 50 percent, because of small cell size and low resistive losses in the materials. The MSOFC operates in the range of 700 to 1000 C, at which temperatures rapid reform of hydrocarbon fuels is expected within the nickel-YSZ fuel channels. Tape casting and hot roll calendering are used to fabricate the MSOFC structure. The performance of the MSOFC has improved significantly during the course of development. The limitation of this system, based on materials resistance alone without interfacial resistances, is 0.093 ohm-sq cm area-specific resistance (ASR). The current typical performance of MSOFC single cells is characterized by ASRs of about 0.4 to 0.5 ohm-sq cm. With further development the ASR is expected to be reduced below 0.2 ohm-sq cm, which will result in power levels greater than 1.4 W/sq cm. The feasibility of the MSOFC concept was proven, and the performance was dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials were minimized. As a result of good matching of these properties, the MSOFC structure was successfully fabricated with few defects, and the system shows excellent promise for development into a practical power source

Self-sustainable protonic ceramic electrochemical cells using a triple conducting electrode for hydrogen and power production.

The protonic ceramic electrochemical cell (PCEC) is an emerging and attractive technology that converts energy between power and hydrogen using solid oxide proton conductors at intermediate temperatures. To achieve efficient electrochemical hydrogen and power production with stable operation, highly robust and durable electrodes are urgently desired to facilitate water oxidation and oxygen reduction reactions, which are the critical steps for both electrolysis and fuel cell operation, especially at reduced temperatures. In this study, a triple conducting oxide of PrNi0.5Co0.5O3-δ perovskite is developed as an oxygen electrode, presenting superior electrochemical performance at 400~600 °C. More importantly, the self-sustainable and reversible operation is successfully demonstrated by converting the generated hydrogen in electrolysis mode to electricity without any hydrogen addition. The excellent electrocatalytic activity is attributed to the considerable proton conduction, as confirmed by hydrogen permeation experiment, remarkable hydration behavior and computations

System for operating solid oxide fuel cell generator on diesel fuel

A system is provided for operating a solid oxide fuel cell generator on diesel fuel. The system includes a hydrodesulfurizer which reduces the sulfur content of commercial and military grade diesel fuel to an acceptable level. Hydrogen which has been previously separated from the process stream is mixed with diesel fuel at low pressure. The diesel/hydrogen mixture is then pressurized and introduced into the hydrodesulfurizer. The hydrodesulfurizer comprises a metal oxide such as ZnO which reacts with hydrogen sulfide in the presence of a metal catalyst to form a metal sulfide and water. After desulfurization, the diesel fuel is reformed and delivered to a hydrogen separator which removes most of the hydrogen from the reformed fuel prior to introduction into a solid oxide fuel cell generator. The separated hydrogen is then selectively delivered to the diesel/hydrogen mixer or to a hydrogen storage unit. The hydrogen storage unit preferably comprises a metal hydride which stores hydrogen in solid form at low pressure. Hydrogen may be discharged from the metal hydride to the diesel/hydrogen mixture at low pressure upon demand, particularly during start-up and shut-down of the system