Oxide Fuel Cell Hybrid System Research Articles

Modelling and simulation of hybrid SOFC-GT systems for distributed generation

This paper focuses on the modelling and simulation of Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT) hybrid systems for Distributed Generation. Independent dynamic models of the main components of the systems have been realized and implemented in the Matlab-Simulink© environment. The models have been used to simulate the behaviour of two plant configurations. Control methodologies have been analyzed and numerical results are provided

Design and sensitivity analysis of a multistage solid oxide fuel cell hybrid system with an inter-cooled-recuperated gas turbine and organic Rankine cycle

A solid oxide fuel cell (SOFC) hybrid system with an inter-cooled-recuperated gas turbine(ICRGT) and organic Rankine cycle (ORC) was designed to address exergy destruction in the burner of a conventional SOFC and gas turbine (GT) system. In unfired mode of this system, SOFC acts as the GT heater and reheater instead of burners; burners are used only to aid load regulation in fired mode. In unfired mode, the system electrical efficiency is 69.86 % and the overall efficiency is 82.22 %. The total exergy destruction of the system is 21.93 % lower than that in fired mode by exergy analysis, which indicates the effectiveness of reducing afterburner exergy destruction, and the superior energy efficiency of this mode. For the design analysis, we analyzed the influence of different factors on the system, including the number of SOFC modules, turbine outlet temperature, burner exhaust into the turbine, oxidant utilization of SOFC cathode(OUC), and fuel utilization of SOFC anode(FUA) on the system. For the sensitivity analysis, we determined the variation rules of the components and system parameters for fuel proportions of 70–105 %. This work provides a reference for optimizing the design and operation of SOFC-GT and other SOFC hybrid systems.

Novel self-pressurized ammonia-powered solid oxide fuel cell hybrid system using anode recirculation with water removal for improving high-altitude performance: Feasibility exploration

Novel self-pressurized ammonia-powered solid oxide fuel cell hybrid system using anode recirculation with water removal for improving high-altitude performance: Feasibility exploration

(Invited) Reach for the Sky: Solid Oxide Fuel Cell Hybrid Systems Enable Carbon-Neutral Flight in ARPA-E’s REEACH Program

The carbon-neutral economy of 2050 may rely on several sustainable fuels, including hydrogen, ammonia, and renewable hydrocarbons. Solid Oxide Fuel Cells (SOFCs) deliver value for each candidate carbon-neutral fuel thanks to their inherent fuel flexibility and high efficiency. This talk examines the additional benefits that can be realized in hybrid systems comprised of an SOFC with an engine bottoming cycle. Developments in ARPA-E’s REEACH program involving SOFC-turbogenerator hybrids for electrified flight will be discussed. The interplays between design and operation of system components can significantly impact the energy storage and power generation (ESPG) system metrics. Modeling work has been performed to inform hybrid system design and will be presented. Finally, next steps for hybrid system deployment at commercial scale will be discussed.

Evaluation and multi-objective salp swarm optimization of a new solid oxide fuel cell hybrid system integrated with an alkali metal thermal electric converter/absorption power cycle

This research introduces a new combination of an alkali metal thermal electric converter (AMTEC) and an absorption power cycle (APC) to boost the performance of the solid oxide fuel cell (SOFC) by recovering the high-quality heat released from the SOFC for further electricity production. The performance criteria of the proposed SOFC/AMTEC/APC hybrid system are mathematically derived using thermodynamic, exergoeconomic, and exergoenvironment-based carbon footprint analysis. Extensive parametric assessment is carried out to evaluate the effect of substantial design parameters on the system's performance criteria. Furthermore, the multi-objective salp swarm algorithm (MSSA) with decision-making techniques is performed to ascertain the hybrid system's maximum power density and minimum cost and environmental impact rates densities. Findings depict the effectiveness and merit of the proposed system with 81% power density improvement compared with the related SOFC-based system. Moreover, the system yields the maximum power density of 9589.37 W/m2, and the corresponding energy and exergy efficiencies are obtained by 55.2% and 57.74%, indicating 59.26% and 53.76% improvements relative to the single SOFC. Furthermore, the minimum cost and CO2 emission rate densities are achieved by 4.26 $/h m2 and 3.32 kgCO2/h m2, respectively, with 31.73% and 42.3% enhancements relative to the base point.

Electricity generation and acid and alkaline recovery from pickled waters/wastewaters through anaerobic digestion, bipolar membrane electrodialysis and solid oxide fuel cell hybrid system

Pickled industrial wastewater (PIWW) containing concentrated organics, ammonia, phosphorus and NaCl is a bioenergy and renewable resource. This study developed a hybrid system of anaerobic digestion (AD), bipolar membrane electrodialysis (BMED) and solid oxide fuel cells (SOFC) to recover biogas and ammonia as renewable fuels, and generate acid and alkaline from four pickle waters/wastewaters. The results demonstrated that anaerobic sludge particles were granulated in hypersaline circumstances and halophilic Bacteroidetes and Firmicutes were two dominant phyla. AD converted 70% of chemical oxygen demand (COD) to biogas and methane yield was 0.051 L-CH4 g-COD−1 on average. The maximum desalination, acid and alkaline generation rates achieved by BMED were 0.304 mol h−1, 0.114 mol h−1, and 0.136 mol h−1, respectively. SOFC used recovered biogas and NH3/H2 and output 500 mW cm−2 and 530 mW cm−2 of peak power densities, respectively. AD-BMED-SOFC hybrid system finally gained 55% of maximum net energy efficiency for the 3rd pickled water. These results signify that AD-BMED-SOFC hybrid system is more feasible and potential when pickled waters are independently treated from pickled wastewaters.

Surge Prevention Techniques for a Turbocharged Solid Oxide Fuel Cell Hybrid System

Abstract Pressurized solid oxide fuel cell (SOFC) systems are one of the most promising technologies to achieve high energy conversion efficiencies and reduce pollutant emissions. The most common solution for pressurization is the integration with a microgas turbine, a device capable of exploiting the residual energy of the exhaust gas to compress the fuel cell air intake and, at the same time, generating additional electrical power. The focus of this study is on an alternative layout, based on an automotive turbocharger, which has been more recently considered by the research community to improve cost effectiveness at a small size (<100 kW), despite reducing slightly the top achievable performance. Such a turbocharged SOFC system poses two main challenges. On one side, the absence of an electrical generator does not allow direct control of the rotational speed, which is determined by the power balance between turbine and compressor. On the other side, the presence of a large volume between compressor and turbine, due to the fuel cell stack, alters the dynamic behavior of the turbocharger during transients, increasing the risk of compressor surge. The pressure oscillations associated with such event are particularly detrimental for the system because they could easily damage the materials of the fuel cells. This paper aims is to investigate different techniques to drive the operative point of the compressor far from the surge condition when needed, reducing the risks related to transients and increasing its reliability. By means of a system dynamic model, developed using the transeo simulation tool by Thermochemical Power Group (TPG), the effect of different antisurge solutions is simulated: (i) intake air conditioning, (ii) water spray at compressor inlet, (iii) air bleed and recirculation, and (iv) installation of an ejector at the compressor intake. The pressurized fuel cell system is simulated with two different control strategies, i.e., constant fuel mass flow and constant turbine inlet temperature. Different solutions are evaluated based on surge margin behavior, both in the short and long terms, but also monitoring other relevant physical quantities of the system, such as compressor pressure ratio and turbocharger rotational speed.

A Study on solid oxide fuel cell hybrid system combined with an existing heavy-duty gas turbine to promote the use of hydrogen

A Study on solid oxide fuel cell hybrid system combined with an existing heavy-duty gas turbine to promote the use of hydrogen

Mathematical Modeling of Solid Oxide Fuel Cell and Gas Turbine Hybrid System for Enhancing Thermal Performance

Fuel cell systems are environment friendly. It is a clean energy generator but it has a low efficiency when it is used alone. Gas turbine also has a lower efficiency around 30% when working alone. Hybrid system is the combination of gas turbine and fuel cell to achieve a higher efficiency around 60-70%. The fuel cell generates the major portion of the plant power output and the gas turbine generates a fraction of total power output. The major advantage of fuel cell is that it is not a heat engine so its efficiency can be 100 % as it is not limited by the Carnot efficiency. Solid oxide fuel cell (SOFC) combined with gas turbine (GT) hybrid plants produce 50 times less nitrous oxide than current conventional gas turbine and 75% less carbon dioxide than coal- fired power plants. This type of hybrid system has a wide application such as decentralised electricity supply in houses and buildings, heat and cooling energy. The present paper includes reviews of the work done in the field of SOFC/GT hybrid system, mathematical modelling using Methane as a fuel to the hybrid system is presented and future scope of work is discussed.

The Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT) Hybrid System Numerical Model

Fuel cells when combined with conventional turbine power plants offer high efficiencies. The feature of certain fuel cells (Solid Oxide Fuel Cell or SOFC, Molten Carbonate Fuel Cell or MCFC), which makes them suitable for hybrid or combined systems, is their high operating temperature. In this work, a detailed thermodynamic model of SOFC and gas turbine hybrid system is simulated in MATLAB. Few configurations of the combined or hybrid cycles are proposed and analyzed. A comparative study based upon performance parameters, such as SOFC power and turbine inlet temperature is used to select the better configuration. Simple thermodynamic models for the compressor and turbine are used during the configuration selection.

Exergy Analysis of Photovoltaic Panels-Coupled Solid Oxide Fuel Cell and Gas Turbine-Electrolyzer Hybrid System

Exergy losses represent true losses of potential to generate a desired product, exergy efficiencies always provide a measure of approach to ideality, and the links between exergy and both economics and environmental impact can help develop improvements. In this study, PV-coupled Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT)-electrolyzer hybrid power generation system is considered to determine the contribution of different hybrid system components in the total exergy loss. The number of panels, the power of SOFC–GT, and the power of electrolyzer can have different values. Therefore, to obtain the optimum combination from ecological, economical, and reliability points of view, a multi-objective optimization algorithm (PESA) is considered. This optimization method chooses a set of optimum solutions that is known as Pareto frontier. The exergy loss of some of these optimum solutions is compared with each other. The effect of panel angle and SOFC–GT fuel type on the hybrid system exergy loss is considered in this study. Also, the hybrid system exergy loss is determined in different months of the year to obtain the worst month from exergy loss view.

Design and Performance Study of a Solid Oxide Fuel Cell and Gas Turbine Hybrid System Applied in Combined Cooling, Heating, and Power System

AbstractBecause of their high efficiency and very low emissions, fuel cells have been one of the choice areas of research in current energy development. The solid oxide fuel cell (SOFC) is a type of high-temperature fuel cell. It has the characteristic of a very high operating temperature of 1,027°C (1,300 K). The SOFC has the main advantage of very high performance efficiency (more than 50%) but also has very high exhaust temperatures. Current studies point out that the combination of the SOFC and gas turbine (GT) can produce efficiency of more than 60%. The exhaust temperature of this hybrid power system can be as high as 227–327°C (500–600 K). With this waste heat utilized, it is possible to further improve the overall efficiency of the system. A simulation program of the SOFC/GT system and the introduction of the concept of combined cooling, heating, and power (CCHP) system have been used in this study. The waste heat of the SOFC/GT hybrid power generation system was used as the heat source to drive a...

425 固体酸化物形燃料電池複合発電システムの高効率化に向けた性能解析(エネルギー有効利用(1))

425 固体酸化物形燃料電池複合発電システムの高効率化に向けた性能解析(エネルギー有効利用(1))

Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

The aim of this study is the development and testing of a control system for solid oxide fuel cell hybrid systems through dynamic simulations. Due to the complexity of these cycles, several parameters, such as the turbine rotational speed, the temperatures within the fuel cell, the differential pressure between the anodic and the cathodic side and the Steam-To-Carbon Ratio need to be monitored and kept within safe limits. Furthermore, in stand-alone conditions the system response to load variations is required to meet the global plant power demand at any time, supporting global load variations and avoiding dangerous or unstable conditions. The plant component models and their integration were carried out in previous studies. This paper focuses on the control strategy required for managing the net electrical power from the system, avoiding malfunctions or damage. Once the control system was developed and tuned, its performance was evaluated by simulating the transient behaviour of the whole hybrid cycle: the results for several operating conditions are presented and discussed.

Generic Real-Time Modeling of Solid Oxide Fuel Cell Hybrid Systems

Real-time (RT) modeling is a recognized approach to monitor advanced systems and to improve control capabilities. Applications of RT models are commonly used in the automotive and aerospace fields. Starting from existing components and models developed in TRANSEO[REF], a new approach, called the multipurpose RT approach, is developed for the solid oxide fuel cell hybrid system application. Original C-based models have been reprogrammed into embedded MATLAB functions for direct use within MATLAB-SIMULINK. Also, models in TRANSEO have been simplified to improve execution time. Using MATLAB’s Real-Time Workshop application, the system model is able to be translated into an autogenerated C-code, and run as an application specific RT executable.

Technological aspects of gas turbine and fuel cell hybrid systems for aircraft: a review

The objective of this work is to make an overview of opportunities and issues related to the aeronautical application of solid oxide fuel cell hybrid systems. The great interest on fuel cells comes from their capacity of producing electric energy with high efficiency at low pollutant production. The application of these systems as full-time auxiliary power units is an interesting alternative in a future scenario, which is supposed to include a More Electric Aircraft and more restrictive environmental standards. A review of the technological aspects of this application is presented. The physical models found in literature were investigated and the results were compared and discussed.

Basic Characteristics of Gas Turbine-Solid Oxide Fuel Cell Hybrid System with Air Recirculation

A Gas turbine (GT) and solid oxide fuel cell (SOFC) hybrid system is expected to achieve a high efficiency over 60% LHV. However, in order to operate the system at such a high efficiency and an increased power density, it is important to keep the whole SOFC temperature as usiform as possible. Cathodic air recirculation is one of the most effective methods to improve the cell temperature distribution. In the present study, numerical simulation of GT-SOFC hybrid system with air recirculation is carried out. The ejector and blower systems are compared, and the effects of recirculation ratio on the overall system performance are evaluated. Furthermore, the part load performance of the ejector system is investigated.

Early start-up of solid oxide fuel cell hybrid systems with ejector cathodic recirculation: Experimental results and model verification

A new test rig, founded in part by Rolls-Royce Fuel Cell Systems Limited, by the EU integrated project ‘FELICITAS’, and by the national project PRIN-2005, has been designed and built at the University of Genova to study different early start-up layouts and strategies for solid oxide fuel cell (SOFC) hybrid systems, using ejector-based cathodic recirculation. The test rig, which is flexible enough to analyse different emulated turbomachine layout (single shaft, two shafts, regenerated cycles or not, and so forth), different ejector configurations, and different stack arrangements, is unique. It also allows the early start-up performance to be fully investigated with particular attention to the analysis of the hybrid system fluid dynamic behaviour when the stack is off and the control system operates at critical conditions. The experiments have been carried out using a patented start-up combustor emulator (outlet temperature higher than 950°C), and monitoring the pressure and temperature quick rise to prevent mechanical and thermal stress to the fuel cell stack and to maintain turbomachine stability. The experimental results have also been used to verify the time-dependent hybrid system models based on TPG-TRANSEO tool. The results show good agreement with experimental data. This is essential to increase confidence with predictive time-dependent simulation tools during the start-up phase, where experimental data are hardly available and fuel cell materials may operate under risky conditions.

Off-design analysis of SOFC hybrid system

This paper sets out the results of mathematical modeling and numerical simulations of the off-design (part-load) operation of the solid oxide fuel cell hybrid system (SOFC-HS). The governing equations of SOFC-HS modeling are given. An adequate simulator of the SOFC stack was made and described. The performance of the SOFC-HS with part- and over-load operation is shown, and adequate maps are given and described. The ranges of possible system operation conditions are determined.

Performance and Combustion Analysis of a Micro Gas Turbine–Solid Oxide Fuel Cell Hybrid System

An integrated methodology aims at estimation of the actual possibility of operating an hybrid system based on a solid oxide fuel cell and a micro gas turbine, by paying special attention to the adaptation of the rotating and stationary components to the off-design conditions. The method leads to the definition of the operating space of the hybrid system, thus allowing detection of optimal choices for an efficient part-load operation. The computational fluid dynamics (CFD)-based analysis of the combustion chamber is addressed to the verification of the response of this component when employed as an afterburner of the residual species from the fuel cell.