Solid Oxide Fuel Cells are a promising technology for Solid Oxide Fuel Cells (SOFC) are a promising technology For high-efficiency electrochemical conversion of a vast range of fuel gas mixtures, thigh operating temperature conditions (650−900 °C) represent a challenge both at system level and at laboratory testing level, in terms of material properties and performance dynamics. In this work a detailed procedural analysis is presented for an innovative all-ceramic compact SOFC test rig and first experimental testing results are reported in terms of polarization curves obtained under parametric variation of operating conditions (H2 content, air ratio λ and temperature) and short-term voltage stability test under load (140 h at 0.3 A/cm2). The electrochemical characterization results confirm the validity of the used all-ceramic cell holder, showing excellent cell performances in terms of polarization. H2 content has the most impact on SOFC performance, followed by temperature and finally... [more]

Chemical compatibility and cation interdiffusion between the double perovskite cobaltites RBaCo2O6−δ (R = Gd, Pr) and proton-conducting electrolyte BaZr0.8Y0.2O3−δ were studied. Chemical interaction was found to occur already at 1100 °C as a result of the partial dissolution of RBaCo2O6−δ (R = Gd, Pr) in BaZr0.8Y0.2O3−δ. Analysis of the element distribution along the cross sections of diffusion couples RBaCo2O6−δ(R = Gd, Pr)|BaZr0.8Y0.2O3−δ showed strong interdiffusion of cations, with cobalt being the most mobile one. Its diffusion depth in the electrolyte reaches up to several hundreds of micrometers. The addition of NiO as a sintering aid to BaZr0.8Y0.2O3−δ promotes cation diffusion especially through the grain boundary mechanism, increasing the diffusion depth of Co. The possible implications of cation interdiffusion on the performance of proton-conducting SOFCs are discussed based on the results obtained.

A thermodynamical analysis of steam reforming of Associated Petroleum Gas (APG) was conducted in the presented research. The reforming process of heavy hydrocarbons for small scale power generation is a complex issue. One of the main issues is that a set of undesired chemical reactions deposit solid carbon and, consequently, block the reactor’s catalytic property. The experimental investigation is crucial to design an APG reforming reactor. However, a numerical simulation is a key tool to design a safe operating condition. Designing the next generation of reactors requires a complex coupling of mathematical models, kinetics, and thermodynamic analysis. In practice, the thermodynamic analysis should be applied in each control volume to assure realistic results. This is not easy to apply in practice since both thermodynamic analysis and CFD modeling can be time-consuming. In this paper, the authors suggest using a mathematical formalism called Parametric Equation Formalism to calculate t... [more]

Solid oxide fuel cell (SOFC) performance degradation analysis and optimization studies are important prerequisites for its commercialization. Reviewing and summarizing SOFC performance degradation studies can help researchers identify research gaps and increase investment in weak areas. In this study, to help researchers purposely improve system performance, degradation mechanism analysis, degradation performance prediction, and degradation performance optimization studies are sorted out. In the review, it is found that the degradation mechanism analysis studies can help to improve the system structure. Degradation mechanism analysis studies can be performed at the stack level and system level, respectively. Degradation performance prediction can help to take measures to mitigate degradation in advance. The main tools of prediction study can be divided into model-based, data-based, electrochemical impedance spectroscopy-based, and image-based approaches. Degradation performance optimiz... [more]

The development of decarbonised systems is being fostered by the increasing demand for technological solutions for the energy transition. Solid Oxide Cells are high-efficiency energy conversion systems that are foreseen for commercial development. They exhibit potential power generation and power-to-gas applications, including a reversible operation mode. Long-lasting high performance is essential for guaranteeing the success of the technology; therefore, it is fundamental to provide diagnosis tools at this early stage of development. In this context, operando analysis techniques help detect and identify incipient degradation phenomena to either counteract damage at its origin or correct operando protocols. Frequent switches from the fuel cell to the electrolyser mode add more challenges with respect to durable performance, and deep knowledge of reverse-operation-induced damage is lacking in the scientific and technical literature. Following on from preliminary experience with button c... [more]

A reliable and efficient power supply for critical infrastructure customers is key to ensuring energy security. Critical infrastructure requires local power sources. Currently, performance requirements for such sources have significantly increased. Apart from high energy efficiency, important requirements include quick start-up time, small size, environmental friendliness, low noise, etc. These may be provided by fuel cells, which are considered the most prospective sources of electric power. However, it is necessary to overcome a number of obstacles limiting fuel cell efficiency in power supply systems for critical infrastructure customers. This paper presents the results of design analysis in the field of fuel cell, hydrogen conversion and power storage technologies. An assessment is given of promising studies aimed at combining the abovementioned technologies to create local power sources to ensure reliable power supply to critical infrastructure objects.

The (Cu,Mn,Co)3O4 (CMC) spinel layer is useful in inhibiting Cr vaporization that deteriorates the solid oxide fuel cell performance. The effectiveness of the spinel layer in suppressing volatile Cr species from the metallic interconnects is strongly dependent on layer density, which is influenced by particle size distributions and agglomerations of the spinel powders. Considering that the material properties were influenced by the synthesizing conditions, this study elucidated the influences of citric acid (fuel) on the structure, morphology, and electrical properties of sol−gel derived CMC spinel powders. Dual-phase CMC spinel powders, consisting of cubic CuMnCoO and tetragonal Mn2CoO4, were successfully synthesized at citrate-to-nitrate (CA/MN) ratios of 0.8, 1.0, and 1.2. An undesired CuCo2O4 phase was observed in spinel powders synthesized at a low CA/MN ratio of 0.5. The CA/MN ratio has influenced not only the phase formation of CMC spinel, but also the particle size distribution... [more]

In this study, cradle-to-product life cycle analyses were conducted for a variety of natural-gas-based and coal-based SOFC power plant conceptual designs, while also accounting for long-term SOFC degradation. For each type of plant, four base case designs were considered: a standalone SOFC plant, a standalone SOFC plant with a steam cycle, an SOFC/GT hybrid plant, and an SOFC/GT hybrid plant with a steam cycle. The boundary of each base case was subsequently expanded to include either wet cooling or dry cooling options and DC to AC conversion, and was subjected to additional cradle-to-product life cycle analyses. The environmental impact results were computed using ReCiPe 2016 (H) and TRACI 2.1 V1.05 in SimaPro. The main factors affecting the midpoint impacts between cases were the plant efficiency and total SOFC manufacturing required over the plant’s lifetime, which were both strongly connected to long-term degradation effects. The findings also showed that the standalone SOFC plant... [more]

SimaPro model used in this work.

Models and codes that were used in this work. Please read the simulation instruction.

In this paper, producing constant power load of 550 MW from systems of Solid Oxide Fuel Cells (SOFCs) operating in varying power output mode was investigated. This is useful because previous research has shown that individual cells can have significant lifetime extensions when operated according to certain dynamic trajectories in which power production decreases over time. In this study, we determined that a constant net power output of a system comprised of many individual SOFC modules can be achieved by scheduling the installation and operation of each SOFC module in a particular manner. All the modules were operated under the optimal operating conditions obtained in our previous optimization study where power output of each module declined over time. The dynamic degradation of SOFCs was taken into ac-count by using a detailed mathematical model of long-term performance degradation as a function of operating conditions. The result is a system in which every 5 days, one new SOFC modul... [more]

A mathematical model of long-term solid oxide fuel cell (SOFC) degradation is proposed, based on a cross-cutting meta-study of SOFC degradation research available in the open literature. This model is able to predict long-term SOFC performance under different operating conditions, and it accounts for the main degradation mechanisms, including: Ni coarsening and oxidation; anode pore size changes; degradation of anode and electrolyte conductivity; and sulfur poisoning. The results of the study indicate that SOFCs initially degrade quickly, but that the degradation rate diminishes significantly after approximately 1200 hours of operation. Consequently, the effects of different factors associated with degradation rate are investigated, including current density, temperature, and partial pressure of H2 in fuel source. Sensitivity analyses show that current density and H2 partial pressure have the highest and the lowest impact, respectively. In addition, the model has been developed to asse... [more]

Models and codes that were used in this work. Please read the simulation instruction.

Solid oxide fuel cells (SOFCs) are a promising next-generation technology for power production from fossil fuels. Because they convert chemical energy into electricity electrochemically, they are generally more efficient than combustion-based power plants due to the thermodynamic limitations of combustion cycles, and accordingly, have lower carbon intensities [1]. However, one of the main drawbacks of SOFCs (and SOFC stacks) is that they can degrade over time in a variety of ways, including accruing damage to the anode, cathode, interconnects, and other cell or stack components. SOFCs are most commonly used in “constant power” mode, in which the fuel flow rate and current density are increased over time to counteract the degradation effects and yield a constant power output. However, higher flow rates cause the degradation rates to grow even faster, resulting in a lifetime potentially as short as 1.5 years [2].

Recent research has found that by operating in “constant voltage” mode,... [more]

One of the largest engineering challenges of our time is finding technical solutions that permit the use of our energy resources in a sustainable way. In order to achieve meaningful and positive change, new energy systems must adhere to the triple bottom line of sustainability. This means that new technical solutions must be economically, socio-politically, and environmentally sustainable, such that they can be rapidly adopted and accepted. The engineering literature is full of a great many technical proposals for new energy systems, but it turns out to be quite hard to objectively look at them all, see through the hype, and decide which are the best and most promising technologies in which to invest our research and development dollars. In this talk, I will present a case study with the results of our recent meta-study covering over 100 candidate electricity generation systems with carbon dioxide capture, in order to determine which are the most promising classes of technologies. I wi... [more]

We conducted a meta-study of CO2 capture processes, examining nearly 100 techno-economic analyses published in the recent open literature. Normally, it is difficult to compare one study to another because each study uses its own set of assumptions, such as plant scale, geography, market parameters, and inconsistent definitions of key metrics such as the cost of CO2 avoided (CCA). In this work, we present normalized versions of these studies using a consistent basis of comparison, such as net power delivered, base year of operation, pipeline CO2 pressure, currency, country of construction, and so on. In so doing, we are able to draw meaningful conclusions and direct comparisons between different classes of CO2 capture technology. The technologies considered include coal and gas-based processes using capture strategies including solvent-based post-combustion carbon capture, gasification-based strategies, membrane-based approaches, oxyfuel combustion, chemical looping combustion, calcium... [more]

We present a new two-level rolling horizon optimization framework applied to a zero-emissions coal-fueled solid-oxide fuel cell power plant with compressed air energy storage for peaking applications. Simulations are performed where the scaled hourly demand for the year 2014 from the Ontario, Canada market is met as closely as possible. It was found that the proposed two-level strategy, by slowly adjusting the SOFC stack power upstream of the storage section, can improve load-following performance by 86% compared to the single-level optimization method proposed previously. A performance analysis indicates that the proposed approach uses the available storage volume to almost its maximum potential, with little improvement possible without changing the system itself. Further improvement to load-following is possible by increasing storage volumes, but with diminishing returns. Using an economically-focused objective function can improve annual revenue generation by as much as 6.5%, but no... [more]

Considering the limited turndown potential of gasification technologies, supplementing a fuel cell turbine hybrid power system with natural gas provides flexibility that could improve economic viability. The dynamic characterization of fuel composition transients is an essential first step in completing the system identification required for controls development. In this work, both open loop and closed loop transient responses of the fuel cell in a solid oxide fuel cell (SOFC) gas turbine (GT) hybrid system to fuel composition changes were experimentally investigated using a cyber-physical fuel cell system. A transition from methane lean syngas to methane rich gases with no turbine speed control was studied. The distributed performance of the fuel cell was analyzed in detail with temporal and spatial resolution across the cell.

Dramatic changes in fuel cell system post combustor thermal output or “thermal effluent” resulting from anode composition changes drove turbine transients th... [more]

This work is a meta-study of CO2 capture processes for coal and natural gas power generation, including technologies such as post-combustion solvent-based carbon capture, the integrated gasification combined cycle process, oxyfuel combustion, membrane-based carbon capture processes, and solid oxide fuel cells. A literature survey of recent techno-economic studies was conducted, compiling relevant data on costs, efficiencies, and other performance metrics. The data were then converted in a consistent fashion to a common standard (such as a consistent net power output, country of construction, currency, base year of operation, and captured CO2 pressure) such that a meaningful and direct comparison of technologies can be made. The processes were compared against a standard status quo power plant without carbon capture to compute metrics such as cost of CO2 emissions avoided to identify the most promising designs and technologies to use for CO2 emissions abatement.