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In energy systems, multi-generation including co-generation and tri-generation has gained tremendous interest in the recent years as an effective way of waste heat recovery. Solid oxide fuel cells are efficient power plants that not only generate electricity with high energy efficiency but also produce high quality waste heat that can be further used for hot and chilled water production. In this work, we present a concept of combined cooling, heating and power (CCHP) energy system which uses solar power as a primary energy source and utilizes a reversible solid oxide fuel cell (R-SOFC) for producing hydrogen and generating electricity in the electrolyser (SOEC) and fuel cell (SOFC) modes, respectively. The system uses “high temperature” metal hydride (MH) for storage of both hydrogen and heat, as well as “low temperature” MH's for the additional heat management, including hot water supply, residential heating during winter time, or cooling/air conditioning during summer time. The work presents evaluation of energy balances of the system components, as well as heat-and-mass transfer modelling of MH beds in metal hydride hydrogen and heat storage system (MHHS; MgH2), MH hydrogen compressor (MHHC; AB5; A = La + Mm, B Ni + Co + Al + Mn) and MH heat pump (MHHP; AB2; A = Ti + Zr, B Mn + Cr + Ni + Fe). A case study of a 3 kWe R-SOFC is analysed and discussed. The results showed that the energy efficiencies are 69.4 and 72.4% in electrolyser and fuel cell modes, respectively. The round-trip COP's of metal hydride heat management system (MHHC + MHHP) are close to 40% for both heating and cooling outputs. Moreover, the tri-generation leads to an improvement of 36% in round-trip energy efficiency as compared to that of a stand-alone R-SOFC.

A method, based on tape-casting, is developed for the manufacture of ceramic interconnects for SOFCs. The development of an optimized process is shown with a discussion of the effects on the precursor-slurry quality and viscosity of, among other things, the concentrations of ammonia, binder and solid particles. Furthermore the effects of some processing modifications, such as the drying rate in the tape casting machine, the speed of the transport band and the doctor blade height on the quality (density and homogeneity) of the green tapes and the finished product are discussed. Improving the degree of dispersion of the primary particles in the slurry was found to make possible improved densification and quality of the thick plates produced as did reducing the drying rate of the wet tapes during the casting process.

This paper describes the development and testing of a 1 kW reversible solid oxide fuel cell intended for energy storage on space exploration missions, particularly for long term Mars exploration. The energy is stored as H2 or CO produced by electrolysis of H2 O or CO2 . The reactants are then converted back to its original composition by producing electricity.The breadboard was operated for 1250 hours alternating between electrolyser mode and fuel cell mode with H2 /H2 O as reactants. During the tests, as long as the mechanical integrity of the system was maintained, no degradation effect was observed. At the end of the test period, the fuel cell was operated for three full cycles (approx. 50 hours) with CO/CO2 as reactants. The performance on CO/CO2 was lower than for hydrogen, but sufficient to be used in a compact energy storage system for Mars exploration.

A challenging barrier for the broad, successful implementation of Reversible Solid Oxide Fuel Cell (RSOFC) technology for Mars application utilizing CO2 from the Martian atmosphere as primary reactant, remains the long term stability by the effective control and minimization of degradation resulting from carbon built up. The perovskitic type oxide material La0.75 Sr0.25 Cr0.9 Fe0.1 O3-δ (LSCF) has been developed and studied for its performance and tolerance to carbon deposition, employed as bi-functional fuel electrode in a Reversible SOFC operating on the CO2 cycle (Solid Oxide Electrolysis Cell/SOEC: CO2 electrolysis, Solid Oxide Fuel Cell/SOFC: power generation through the electrochemical reaction of CO and oxygen). A commercial state-of-the-art NiO-YSZ (8% mol Y2 O3 stabilized ZrO2 ) cermet was used as reference material. CO2 electrolysis and fuel cell operation in 70% CO/CO2 were studied in the temperature range of 900-1000°C. YSZ was used as electrolyte while LSM-YSZ/LSM (La0.2 Sr0.8 MnO3 ) as oxygen electrode. Results showed that LSCF had high and stable performance under RSOFC operation.

A dip-coating method was used to obtain 8YSZ thin films formed from nanoparticles on anode support for SOFC applications. 8YSZ nanopowder was obtained via a modified sol–gel method using sucrose and pectin as organic precursors. The nanoparticles were suspended in ethanol using phosphate ester (PE) and polyvinyl butyral (PVB) as dispersant and binder, respectively. The microstructure of the sintered films were analyzed with SEM. The suspension preparation conditions were tuned in order to achieve high initial green density of the 8YSZ films subsequently determining the final sintered microstructure. In addition, the effect of the linear shrinkage of the anode substrate on the 8YSZ film microstructure was studied.

The electronic charge carrier concentration in La1−x Sr x FeO3−δ was shown to depend on the partial pressure of O2 (pO 2). Chemical diffusion coefficient and surface exchange coefficient, k chem, were determined by conductivity relaxation in O2/N2 and CO/CO2 mixtures. k chem was proportional to pO 2 1.06 in O2/N2, while in CO/CO2 k chem was controlled by a reaction mechanism involving both CO and CO2.

Preparation conditions for obtaining dense 8YSZ electrolyte films by dip-coating on NiO–YSZ anode electrode substrates for SOFC application were investigated with focus on the co-sintering process. The NiO–YSZ substrates were prepared from nanoparticles which were obtained by a single modified sol–gel process using sucrose and pectin as organic precursors. The microstructure and the morphology of the product powders were analyzed by X-ray diffraction and TEM. A thin film of 8YSZ was obtained by a single-step dip-coating process using phosphate ester (PE) as dispersant and polyvinyl butyral (PVB) as binder. The microstructure of the sintered films was analyzed with SEM. The effect of the sinterability of the anode substrate on the 8YSZ film quality was studied. Fully dense electrolyte films were obtained on anode substrates which held a linear shrinkage of ∼23%. The use of substrates with a linear shrinkage below 23%, resulted in a poorly densified 8YSZ microstructure.

Cation tracer diffusion coefficients in La 1− x Sr x FeO 3− δ , ( x = 0 and 0.1) at temperatures ranging from 1173 to 1373 K have been investigated by secondary ion mass spectrometry (SIMS) for both A-site and B-site diffusion applying Y 3+ and Cr 3+ as tracer ions. B-site impurity (represented by Cr) diffusion was found to be faster than A-site impurity (represented by Y) diffusion for LaFeO 3 in the whole temperature interval investigated and for La 0.9 Sr 0.1 FeO 3 at temperatures less than 1273 K. The obtained activation energies for bulk diffusion in La 0.9 Sr 0.1 FeO 3− δ were 168 ± 24 kJ/mol for the Y tracer and 150 ± 30 kJ/mol for the Cr tracer, which are significantly lower than activation energies reported from diffusion couple experiments. The large variation in reported activation energies can be explained in terms of the difference in cation vacancy populations between the two experimental techniques. The diffusion coefficients were also clearly affected by a first order phase transition at approx. 1263 K in pure LaFeO 3. The obtained grain boundary diffusion coefficients were about five order of magnitude higher than the bulk diffusion coefficients, with an activation energy of 128 ± 28 kJ/mol.

This paper presents a comprehensive model for a unit solid oxide fuel cell (SOFC). It covers all parts of the cell including fluid and porous solid phases. The electrochemical and transport processes involved in an SOFC can thereby be taken into account. The commercial computational fluid dynamic package Star-CD along with built-in user-defined subroutines is adapted for an anode-supported unit cell. Some results such as gas concentration, temperature distribution and current density are presented at the end of the paper.

Short-term tests showing the influence sulfur has on solid oxide fuel cell (SOFC) performance have been performed. The experiments were performed using two single-cell SOFC setups operated at 800 d ...

Crystal structure and thermal properties of La 1-x Sr x FeO 3-δ (x = 0, 0.1, 0.3, 0.4, 0.5, and 0.75) have been studied by high-temperature X-ray diffraction and thermal analysis in air and nitrogen (p(O 2 ) 10 -3 atm) atmosphere. The first-order phase transition from orthorhombic-to-rhombohedral La 1-x -Sr x FeO 3-δ (x = 0, 0.1) was strongly shifted to lower temperatures with increasing Sr content. The phase-transition temperature was observed significantly lower in polycrystalline ceramics compared with fine powders. The temperature depression of the phase transition in the ceramics was qualitatively explained by stresses induced both by the anisotropic thermal expansion of LaFeO3 and the observed volume contraction of the phase transition. Rhombohedral La 1-x Sr x -FeO 3-δ (x = 0.3, 0.4, 0.5) were observed to transform to the cubic perovskite structure during heating. The second-order phase-transition temperature decreased with increasing Sr content and decreasing partial pressure of oxygen. On the basis of the present findings, a pseudobinary phase diagram of the LaFeO 3 -SrFeO 3-δ system is presented. Finally, a severely nonlinear thermal expansion was observed for the Sr-rich materials at high temperature. The high thermal expansion in this region is due to a chemical expansion resulting from a reduction of the valence state of Fe.

During the recent years, SOFC research has mainly been aimed at reducing the capital cost to effectively compete with other power generation technologies. CMR Prototech, Norway is a provider of technical solutions, product designs and tools for various application areas. Currently, CMR Prototech is planning to develop 2 MW modular fuel cell systems for subsea operation. Each module consists of 200 stacks, each stack producing 10kW. In order to address the technical challenges faced during this development and to make SOFC technology feasible for offshore applications more research on fuel cells in marine environment is necessary. This research was aimed at determining the effects of a) reducing partial pressure of oxygen and b) NaCl contamination on the performance of the SOFC cathode of a single SOFC cell. This present paper focuses on the effect of oxygen partial pressure. Single cell tests were performed in a versatile test station, fully automated and controlled using LabVIEW programming. The fluid handling system with mass flow controllers and four-points measurement probes along with field-point connections were installed in the test station. A set of experiments were conducted, reducing the partial pressure of oxygen supplied to the cathode stopwise (at thre relevant temperatures, namely 800, 850 and 900oC). All the cells were characterized and analyzed by I-V curves. The grain structures of the cells were characterized by scanning electron microscopy (SEM) before and after the experiments.

One of the fundamental impediments to the wide-spread commercialization of fuel cell technology is questions about the robustness and durability of this type of installation. In the course of a larger experimental program designed to answer these questions, specifically for operation in a marine environment, a series of tests were carried out to determine the sensitivity of SOFC cathodes to salt contamination in the gaseous feed stream. The salt content in the feed stream was varied by adding crystalline salt in the inlet piping, allowing it to sublimate at temperatures designed to give the desired salt concentration in the feed to the cathode. Both short-term and long-term degradation tests were performed, and in addition to characterizing the performance using the I-V curves, the microstructure of the cathodes were investigated using scanning electron microscopy before and after each run. The tests showed that there is degradation of the cathode due to the salt contamination, both in the short and the long term. While it was difficult to determine the reason for the short-term degradation, the long-term degradation was much more severe, and can be attributed to two effects: the salt appeared as crystals in the cathode microstructure and had a coarsening effect, and the presence of the salt gave rise to delamination of the cell at the cathode-electrolyte interface, something that was not observed under otherwise like operation conditions and -duration without salt contamination.

The ZEG-technology (Zero Emission Gas power) is a hybrid technology for co-production of electricity and hydrogen from hydrocarbon fuels, with integrated CO2 capture. The technology has a potential for a very high total efficiency, more than 80% in cluding close to 100% CO2 capture and compression of CO2 to 110 bar. At present the technology is being tested in a 50 kW p lant based on biomethane for demonstration of 70% overall energy efficiency and the production of green hydrogen and electricity with integrated CO2 capture. This paper present the plant and initial test results as well as the ongoing work. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of GHGT.

Tracer diffusion coefficients in La 1− x Sr x FeO 3 , x =0 and 0.1 from 900 to 1100 °C for both A- and B-site diffusions were examined with secondary ion mass spectrometry (SIMS) applying Y 3+ and Cr 3+ as tracers. In both compositions, the B-site diffusion, represented by Cr, was found to be faster than the A-site diffusion, represented by Y. The obtained activation energies for bulk diffusion in La 0.9 Sr 0.1 FeO 3 were 168±24 kJ/mol for the Y tracer and 150±30 kJ/mol for the Cr tracer. The 18 O-tracer diffusion coefficients were found to be significantly higher in La 0.9 Sr 0.1 FeO 3 compared with LaFeO 3 .