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In order to improve the energy efficiency of the Sabatier reactor-based power-to-gas process, molten carbonate fuel cells and solid oxide electrolyzers were installed instead of a conventional amine CO 2 capture system and a classical alkaline electrolyzer. The plant is a multi-module prototype with a nominal capacity of 50 kW consisting of two SOE-MCFC units. The system was commissioned in 2022. The article describes the theoretical basis. The initial assumptions that were formulated at the stage of preparing for the research investment, as well as the deviations from them that became the result of detailed design were presented. The developed startup and shutdown procedures, as well as the first results of pioneering research were shown. The trial operation of the system was intended to provide information on integrated SOE-MCFC module and its performance and efficiency. The basic barriers for market implementation and recommendations for future research were discussed. The optimal operating point for hydrogen production needed 35.8 kWh/kgH 2. Thus, electrical energy conversion to chemical energy efficiency is 93.9%. Flow preheating and electrical auxiliary heater power are not included. An MCFC at its ideal functioning point (around 4 kW el) outputs 5.4 kg/h of CO 2 separated. • Operational experience of upgraded novel P2G installation is reported. • A start-up procedure of MCFC-SOE tandem in proposed and experimentally verified. • Energy required for synthesis of a kilogram of hydrogen was 35.8 kWh/kgH 2. [ABSTRACT FROM AUTHOR]

The aim of the paper is to examine the performance of molten carbonate fuel cell, which is supplied with a raw bioethanol, i.e. bioethanol which origins directly from fruit fermentation, without pre-treatment of fermentation products. The composition of raw bioethanol was precisely determined and then the impact of raw bioethanol on the degradation of molten carbonate fuel cells was examined. Steam to carbon ratio of the biofuel has been determined as 5.7 (in comparison to stoichiometry of reaction) which allowed for estimation of hydrogen production during steam reforming process taking place in the anode channel. The results in the form of current-voltage curve was obtained and compared with the same fuel cell fed with pure hydrogen, while the amount of hydrogen was defined as identical with the one after steam reforming of biofuel taking place in the nickel anode channel. Relevant literature studies were focused on the purified fuel or examination of the impact of individual components. Our study proved carbon deposition is not a problem, however solid particles contamination in fermentation product makes it impossible to use fuel cell fueled with fermentation product for longer periods, and prior to supplying fuel cell the bioethanol purification is required. A raw biofuel with its impurities did not have any impact on the anode and current collector surface from physical point of view, but Electrochemical Impedance Spectroscopy analysis shows visible increase of ohmic loses. • Homemade first generation bioethanol composition have been examined. • Manufactured bioethanol has been delivered directly to the MCFC anode without purification. • Performance of MCFC fueled with impure bioethanol has been investigated. • Effect of steam reforming for hydrogen generation and steam to carbon ratio were evaluated. • Pollution on the anode after cell operation was investigated with SEM and EIS. [ABSTRACT FROM AUTHOR]

This paper presents the results of research into improving the ionic conductivity of Molten Carbonate Fuel Cell by modifying the matrix material. So far, we have succeeded in using materials such as YSZ and SDC, but we are now trying to use powders based on Ba Na and TiO 2. These materials are characterized by their oxygen ion conductivity at elevated temperatures. A matrix of these materials was produced and used to build MCFCs. Based on the experiments carried out and the mathematical model of the fuel cell, the contribution of the oxygen ion conductivity to the total ionic conductivity was determined. • Research on oxygen ion conduction materials was performed. • BNT material has best oxygen ion conductivity parameters and was chosen for experiments. • New matrix made of BNT was manufactured. • Composite Li/K and BNT membrane was investigated under EIS and in fuel cell. • Model including ionic conductivity and tortuosity is presented and validated. [ABSTRACT FROM AUTHOR]

This paper reports the performance of a molten carbonate fuel cell (MCFC) fed directly with liquid fuels referenced against results with hydrogen fuel in experiments conducted by the research team. Alcohols have greater energy density than pure hydrogen in normal conditions and, if presented as biofuels, the MCFC can be deemed a renewable energy source. For evaluation purposes various alcohols occurring in standard conditions in the liquid state were used for electricity generation in the MCFC: methanol, ethanol, propanol, butanol and glycerol. Since these alcohols can be subjected to steam reforming when mixed with water in specific ratios, they can be delivered directly in the liquid state to the fuel cell, where hydrogen is released and used to produce electricity and heat. The alcohols were mixed with water in ratios of 1:2, 1:3, 1:4. The results were compared to the MCFC fed with pure hydrogen as a fuel. In terms of power referenced to hydrogen (100%), the maximums achieved were 78% for butanol, 80% for glycerol, 83% for propanol, 86% for ethanol and 93% for methanol in comparison to the same amount of hydrogen delivered to the fuel cell in ideal steam reforming situation. Threats such as carbon deposition on the fuel cell surface were also evaluated. • MCFC fed directly with various mixtures of alcohols and water have been studied. • The steam reforming of mixtures of alcohols and water generates energy. • Temperature and anode material provide the necessary conditions for steam reforming. • Maximum power compared to hydrogen fuel for various fuels ranges between 78 and 93%. • Carbon deposition in the anode channel of commercial units can be a problem. [ABSTRACT FROM AUTHOR]

The paper aims to examine the possibility of improving the manufacturing process for MCFC cathodes. using noble, semi-precious, and rare earth metals sourced from waste electric and electronic equipment (WEEE). As MCFC components are not particularly sensitive to ceramic and metal impurities. The addition of noble metals recovered from WEEE as catalysts are economically justifiable. The reported experimental research revealed the positive impact of MCFC cathode fabricated with 20% recycled electronic scrap. Especially the cell with powder marked as 4/1 enjoyed much better performance operating at 550 °C than the reference cell. During the operation at a temperature of 650 °C, the cell with powder marked as 4/1 has almost the same performance as the reference cell, i.e., 1.01 V OCV and power density of 0.13 A/cm2. The cell with cathode with 4/2 powder has the worst performance – current density of 0.09 A/cm2 and OCV of 0.97 V. [Display omitted] • Rare earth elements separated by positive charge contains less cerium than separated by negative charge. • The maximum current densities and Open Circuit Values are similar as reference case for maximum gas flows. • The maximum current densities and Oper Circuit Voltages are better with additives for lower operational temperature. [ABSTRACT FROM AUTHOR]

In this study, two types of high temperature electrolyzers (O=SOE and H+SOE) were investigated for hydrogen generation in relation to nuclear power plant operations. The analysis encompasses the thermal integration of proton and ion conducting solid oxide electrolyzers, which are fed with steam generated in the nuclear plant. Under consideration in the study was the steam turbine cycle of an AP1000 nuclear power plant. The main parameters of electrolysis were tailored to match the typical operating temperature of the electrolyzers, and the water utilization factor was set at the same value for the two technologies under consideration. There are some advantages to applying high temperature electrolysis to the deaerator steam feed: first, there is almost no modification of the nuclear steam turbine cycle; second, flexibility of the nuclear power plant rises by 20% with almost constant thermal load of the nuclear reactor; and third, high pressure hydrogen is obtained for commercial purposes. The analysis concludes that hydrogen can be produced in electrolyzers integrated with nuclear plants at an energy cost of 38.83 and 37.55 kWh kg H2 −1 for protonic and ionic solid oxide electrolyzers, respectively. • Study addressed the coupling of solid oxide electrolysers with nuclear plant. • Oxygen ion and proton conducting solid oxide electrolyzers were modelled. • Analysis of hydrogen generation using high temperature electrolysis was performed. • Electric power demand for producing hydrogen in the cycle was computed. • Values of 38.83 and 37.55 kWh/kg H 2 were found for H+ and O= SOE, respectively. [ABSTRACT FROM AUTHOR]

It is proposed that dual conductive electrolytes have the potential to improve properties of MCFC by using oxygen ion conductors as matrix material, creating what is termed composite electrolyte. In this work we present the results of testing a novel type of electrolyte of molten carbonate fuel cell which consists of Yttria Stabilized Zirconia impregnated by Lithium/Potassium carbonates. Polarization curves were obtained for temperatures between 500 °C and 800 °C. Without very accurate measurements it is not easy to determine the additional electric charge provided by oxygen ions (O=). We made an attempt to build a mathematical model which takes into account both conductivities and, based on the model, estimated the ratio of electric charge provided by oxygen ions and carbonate ions. • We investigated double conducting electrolytes for Molten Carbonate Fuel Cell. • The investigation was done by both experimental and modeling methods. • We found small infuence done by ionic conductor. • The infunece is so small, that the results are not so evident. [ABSTRACT FROM AUTHOR]

The research presents an overview of the possibilities of using boron-containing compounds as electrolytes for fuel cells. The main assumption here is to develop a molten carbonate fuel cell type power source, where the molten electrolyte is kept by a ceramic matrix between the electrodes. In the cases which are described in this study, attempts were made to develop electrolytes based on borates. Whereas the reported studies contain very little information on this subject, it was possible to identify several promising compounds and to extrapolate their performance to higher temperatures. Reported data on the temperature at eutectic points suggest that the operating range of such electrolytes is at a level like the molten carbonate fuel cell. The study presents a proposal for a mathematical model of a new type of fuel cell based on molten borates. The mathematical model is based on the reduced order model, supplemented with the influence of the ceramic matrix on the resulting ionic conductivity of the electrolyte layer. The model was used to determine potential performances for a few selected borates and a sensitivity analysis of selected geometric parameters was performed for the best of them. The results obtained were compared against the standard molten carbonate fuel cell. • Conductivities of various boron compounds have been investigated and compared. • Application of boron-containing compounds in fuel cells electrolyte has been analyzed. • A model of molten borate fuel cell has been developed. • Borates occurring to have higher potential than carbonates what might result in higher efficiency. [ABSTRACT FROM AUTHOR]

The idea of control strategy of SOFC operating to meet demand of a public utility building was presented. The strategy was formulated with the support of Artificial Neural Network. The network was used to predict the demand for electricity. The calculations were carried out on the example of a building of the Institute of Heat Engineering Warsaw University of Technology. The control strategy is influenced by various factors depending on changes in market conditions and operating characteristics of the cell. We can define different objective functions eg: working for own needs, for maximum profit and maximum service life. The article presents a simulation of SOFC operation for demand profile of the IHE building from the selected time period. [ABSTRACT FROM AUTHOR]

This paper describes the fuel cell research and development activities at Warsaw University of Technology by reviewing in particular the progress made in the development of Molten Carbonate Fuel Cells (MCFC). Porous nickel electrodes were prepared by loose powder sintering, slurry casting and tape casting techniques. These efforts are directed toward gaining a better understanding of and improving the components of molten carbonate fuel cells operating at temperatures near 650°C. Cell testing is performed to assess individual and collective component behavior. Nickel electrodes oxidized under in situ conditions were used as the cathode. The tape casting technique was used to make the matrix. [ABSTRACT FROM AUTHOR]

A variant analysis of a potential configuration of a peak-load system which is based on SOE/SOFC module and hydrogen storage is presented in this article. The most rational configuration of the power plant with the SOE/SOFC appears to reach a high total electricity-to-electricity conversion rate with small and medium size plants. The system contains the minimum amount of devices where the anode side of the SOFC is exposed to the hydrogen storage directly. In this solution no compressors or pumps are needed and the system has no moving parts. Oxygen is then released to the surrounding environment or can be stored in an additional tank. In theory, it is possible to obtain higher efficiencies, but this requires much higher capital expenditures (additional heat exchangers, gas turbines, set of heat regeneration heat exchangers, etc.) and much higher parameters of working media in the system (1400 C, 30 bar). The absolute efficiency of the system depends on the assumptions made and the way in which the mathematical model was developed. It may change due to them, hence the presented analysis is qualitative rather than quantitative. [ABSTRACT FROM AUTHOR]

The aim of the paper is to simulate multi-tank storage with the thermocline moving from tank to tank and compare the results against single tank storage. No analysis of this nature has previously been performed. The results lend added impetus to developing this new type of thermal energy storage, especially as heat losses through insulation have already been reduced a minimum. Dividing a seasonal thermal energy storage tank into smaller tanks reduces the negative effect of heat transfer through the thermocline. The work is a continuation of the concept already proposed in available literature of using multiple solar energy stores, but we focus mainly on developing a dynamic model of a system of this type and presenting the results of a time and thermocline dependent simulation. The study also encompassed examination of the thickness of thermal insulation of the storage tanks, with definitions of its critical size. Our study revealed that the use of multi-tank thermal energy storage reduces heat loss through the thermocline. This is illustrated mainly by changes in water temperature in the upper part of the tank, which fluctuates across a much smaller range than for a single tank. In the single tank system, the temperature drops below 60 °C, whereas for the multi-tank system it always remains above 64 °C. In addition, in the multi-tank solution the loss caused by the thermocline occurs in only one tank, leaving 3/4 of the storage system unaffected by thermocline loss. • The concept of multi tank seasonal thermal energy storage is examined. • The examination is based on the dynamic modeling. • Results are compared with the single tank thermal energy storage systems. • The examined system is more efficient due thermocline losses limitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrolyzer and fuel cell integrated in an enhanced power-to-gas system. • No energy penalty for CO 2 capture, in a system with lower power requirements. • CO 2 separation exceeds 90 percent. This study outlines a concept for improving a power-to-gas (P2G) system through the implementation of highly efficient high-temperature electrolysis combined with a molten carbonate fuel cell (MCFC) as a CO 2 capture unit for a power plant. Laboratory scale experiments demonstrate that the MCFC could be used for CO 2 separation, opening the way to capture of CO 2 from flue gases at coal-fired power stations, while maintaining both high electric efficiency and a high CO 2 separation factor. Improved energy efficiency can be achieved by the lower electricity requirement of high temperature electrolysis compared to other technologies. Results obtained from experimental investigations show that a CO 2 separation rate in excess of 90 % is achievable through adjusting the cathode inlet flow. It should be noted that flue gas must be mixed with air before delivery to the MCFC. Controlled flow of inlet gases to the anode can raise electric efficiency to above 35 % for both laboratory-size and full-scale MCFC. The benefits of the concept are manifested by lower power consumption of the system and no energy penalty for the CO 2 capture process. Additionally, the system enjoys good thermal management because all devices run at elevated temperatures (Sabatier reactor at 300 °C, MCFC at 650 °C, solid oxide electrolyzer at 700–800 °C). The proposed improvements increase the system's competitiveness relative to alternative P2G systems and reduce the price of substitute natural gas. Secondly, it will eliminate the consumption of heat from the host coal-fired power plant. Thirdly, the entire system will be more straightforward, compact, and modular, allowing any future scale-up to be implemented without technological difficulties. Finally, the amount of energy required to produce hydrogen will decline by around 25 %. [ABSTRACT FROM AUTHOR]

Molten Carbonate Fuel Cells (MCFCs) can be used as CO 2 separators in fossil fuel power plants. Fossil fuel power plants emit flue gases with SO 2 contaminants, thus the influence of SO 2 on the operation of MCFC is investigated both theoretically and experimentally. The influence of SO 2 contaminants (up 680 ppm) on MCFC performance was examined. The experimental investigation revealed there is a boundary limit where SO 2 contamination could increase the MCFC voltage. [ABSTRACT FROM AUTHOR]

The paper presents an experimental investigation of a Molten Carbonate Fuel Cell (MCFC) fueled by methane in order to predict how to reduce CO 2 emissions from the flue gas of a real power plant. MCFCs can be placed in the flue gas stream of a fossil fired power plant to separate CO 2 by transferring it from the cathode side to the anode side. As a result, a mixture of CO 2 and H 2 O is separated from which pure CO 2 can be obtained through condensation of water. The main advantages of this solution are: additional power generation, reduced CO 2 emissions and higher system efficiency. Furthermore, coal plants seem to be the ideal candidate to retrofit with MCFC plant due to their high exhaust CO 2 content and to the low cost of the fuel that encourages its application despite the narrower emission requirement. The experimental results show that use of an MCFC could reduce CO 2 emissions by 90% with over 30% efficiency in additional power generation and by demonstrating a broad range of different operative conditions. [ABSTRACT FROM AUTHOR]

The article presents an analysis of real operational data of a Seasonal Thermal Energy Storage system connected to a local heating grid. 8 years of operation time was analyzed to determine typical scenarios for cooperation with the heating grid and solar collectors. The research shows that three main working modes of the accumulator may be particularized: charging, discharging and transient modes, and that the maximum speed of charge/discharge is on average below 0.3°C/day. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents an experimental investigation of using a Molten Carbonate Fuel Cell (MCFC) to reduce CO2 emission from the flue gas of a lignite fired boiler. The MCFC is placed in the flue gas stream and separates CO2 from the cathode side to the anode side. As a result, a mixture of CO2 and H2O is obtained from which pure CO2 can be obtained through condensation of water and carbon dioxide. The main advantages of this solution are: additional electricity generated, reduced CO2 emissions and higher system efficiency. The results obtained show that the use of an MCFC could reduce CO2 emissions by 90% with over 30% efficiency in additional power generation. [Copyright &y& Elsevier]

Abstract: The mathematical model of the Molten Carbonate Fuel Cell (MCFC) is presented. The new approach for modeling the voltage of MCFC is proposed. Electrochemical, thermal, electrical and flow parameters are collected in the 0-D mathematical model. The aim was to combine all cell working conditions in as a low number of factors as possible and to have the factors relatively easy to determine. A validation process for various experimental data was made and adequate results are shown. The presented model was validated for various fuel mixtures in relatively wide ranges of parameters. A distinction is made between the “design-point” and “off-design operation”. [Copyright &y& Elsevier]

Abstract: The paper presents a control strategy concept for a Solid Oxide Fuel Cell (SOFC) to work in Distributed Generation. The control strategy is based on several factors and directs the operation of the SOFC in the context of changes occurring in the market, while taking into account the operating characteristics of the power unit. The control strategy is defined by an appropriate objective function: for example, work at maximum profit, maximum service life, etc. The results of simulations of a fuel cell at chosen loads are presented. Daily changes in the prices of fuel and electricity are factored into the simulations. [Copyright &y& Elsevier]

Abstract: The paper presents a control strategy concept for an Internal Combustion (IC) engine to work in Distributed Generation. The control strategy is based on several factors and directs the operation of the IC engine in the context of changes occurring in the market, while taking into account the operating characteristics of the engine. The control strategy is defined by an appropriate objective function: for example, work at maximum profit, maximum service life, etc. The results of simulations of a piston engine at chosen loads are presented. Daily changes in the prices of fuel and electricity are factored into the simulations. [Copyright &y& Elsevier]

Abstract: Based on mathematical modelling and numerical simulations, the control strategy for a molten carbonate fuel cell hybrid system (MCFC-HS) is presented. Adequate maps of performances with three independent parameters are shown. The independent parameters are as follows: stack current, fuel mass flow and compressor outlet pressure. Those parameters can be controlled by external load, fuel valve and turbine–compressor shaft speed, respectively. The control system is purposed to meet many constraints: e.g. stack temperature, steam-to-carbon ratio, compressor surge limitation, etc. The aim is to achieve maximum efficiency of power generated within those constraints. Governing equations of MCFC-HS modelling are given. An adequate simulator for the MCFC module was produced and described. Based on this simulator, the control strategy was obtained. The performance of this MCFC-HS is shown in various working environments. [Copyright &y& Elsevier]

Abstract: The Artificial Neural Network (ANN) can be applied to simulate an object''s behaviour without an algorithmic solution merely by utilizing available experimental data. The ANN is used for modelling singular cell behaviour. The optimal network architecture is shown and commented. The error backpropagation algorithm was used for an ANN training procedure. The ANN based SOFC model has the following input parameters: current density, temperature, fuel volume flow density (mlmin−1 cm−2), and oxidant volume flow density. Based on these input parameters, cell voltage is predicted by the model. Obtained results show that the ANN can be successfully used for modelling the singular solid oxide fuel cell. The self-learning process of the ANN provides an opportunity to adapt the model to new situations (e.g. certain types of impurities at inlet streams etc.). Based on the results from this study it can be concluded that, by using the ANN, an SOFC can be modelled with relatively high accuracy. In contrast to traditional models, the ANN is able to predict cell voltage without knowledge of numerous physical, chemical, and electrochemical factors. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

• An alternative approach for voltage prediction of a single cell H-SOFC has been developed. • Model is based only on physical, geometrical and material properties of the fuel cell. • A validation process is done. The aim of this study is to develop a new approach for modeling the voltage of H-SOFC. The proposed 0-D model collects electrochemical, thermal, electrical and flow parameters. The main aim is to have a combination of all cell working conditions in as a low number of factors as possible and to have factors that are relatively easy to determine. Various experimental data was collected and the results of the validation process are shown. Various fuel mixtures across relatively wide ranges of parameters were used to validate the model. [ABSTRACT FROM AUTHOR]

Molten Carbonate Fuel Cells (MCFC) offer several advantages that are accelerating the research and development effort. Recent advances include improved materials, new fabrication techniques and new designs, flow configurations and applications. Nevertheless, several factors are holding back large scale implementation of fuel cells, especially in distributed energy generation, a major one being their long response time to changing parameters. Whereas alternative mathematical models of the molten carbonate fuel cell stack have been developed over the last decade, there are no reported analyses of regarding the application of models for emergency scenarios such as fuel cell malfunctions. This paper presents the 0D model of MCFC, calibrated to the appropriate available experimental data. This study investigates a generic molten fuel cell stack with nominal power output of 1 kWel. As daily, weekly and monthly variations in the electrical power load are expected, there is a need to develop numerical tools to predict the unit's performance with high accuracy. Hence, a fully physical dynamic model of an MCFC stack was developed and implemented in Aspen HYSYS 10 modeling software to enable predictive analysis of the dynamic response. The model is used to simulate a number of few malfunctions with 5. 66% broken cells in the stack. Losses of performance are obtained, manifested by rising operating temperature and falling power output. Moreover, a number of emergency operation scenarios were investigated, such as sudden loss of electric load, fuel and oxidiant supply. The presented model exhibits high accuracy and accounts for thermal and electrochemical processes and parameters. The paper presents the methodology used in the study to analyze the sensitivity of key scenarios such as load changes and emergencies. Further functionality of the model, which was validated using real operating data, is discussed. • Dynamic model of a Molten Carbonate Fuel Cell 1 kW stackis proposed. • The model was calibrated to the appropriate available experimental data. • The load changes and emergency situations were examined. [ABSTRACT FROM AUTHOR]

Molten carbonate fuel cells (MCFCs) are promising high temperature power generating devices. However, unlike solid oxide fuel cells (SOFCs) they utilize a liquid electrolyte which must be immobilized in a porous matrix. In this paper, a slurry composition for lithium aluminate ( γ -LiAlO 2 ) matrix was developed and green matrices were subsequently formed by the tape casting method. In order to achieve the desired structure of the matrix (pore size, porosity) γ -LiAlO 2 powder was milled in a planetary ball mill for 18 h with a solvent, dispersant and defoamer. After this step, other ingredients were added, including a binder and plasticizer to obtain optimal rheology of the slurry. Cell tests confirmed optimal performance of the matrix compared to the third party reference γ -LiAlO 2 matrices. Burned out matrix was characterized by scanning electron microscopy (SEM) and laser diffraction in order to determine the γ -LiAlO 2 powder particle size and morphology. The results show that high-energy milling enabled a fine pore structure and high specific surface area of the matrix to be obtained in a relatively short time, compared to conventional fabrication routes. The matrix structure obtained within this study is suitable for high performance operation of MCFC. [ABSTRACT FROM AUTHOR]

• The model of molten carbonate fuel cell was created in ASPEN Hysys environment. • The model of system integration of the MCFC with LNG-based piston engine was created in ASPEN Hysys environment. • Also, the short review of the use of fuel cell in marine application is presented. • The sensitivity analysis of MCFC-piston engine fueled by LNG were generated based of the model. This study presents a proposed hybrid ship propulsion system combining an internal combustion engine and a molten carbonate fuel cell both powered by liquefied natural gas (LNG). Exhaust from the internal combustion engine is used as a CO 2 source for cell operation, reducing CO 2 emissions. Use of fuel stored at very low temperature requires heat for evaporation purposes. The fuel is used to condense water vapor from the fuel cell exhaust gases, returning the remainder to the fuel cell with the right amount of water. This solution increases the electricity generation efficiency of the fuel cell. We analyzed two different system configurations that differ in the way the anode off-gas is recirculated. In the first, all the unoxidized fuel is recirculated to the anode inlet; in the second, off-gas is joined with engine flue gas, and residual fuel burned in a combustion chamber before being sent to the cathode of the fuel cell, allowing to maintain an optimal CO 2 :O 2 ratio in the cathode flow of the fuel cell. A detailed numerical model of the system including cell operation was created in Aspen Hysys and optimized to maximize the system efficiency. Results showed that in configuration I the efficiency gain is about 4.9% with respect to the traditional engine. In configuration II the efficiency gain was only about 0.8%. We also analyzed the sensitivity of the systems from the point of view of the limitations occurring here (e.g., steam-to-carbon ratio or operating temperature). Finally, we discussed the size of such a fuel cell in relation to the internal combustion engine, the entire ship, as well as the impact of the increase in efficiency on the range of the vessel. [ABSTRACT FROM AUTHOR]

Highlights • The reclamation of retired EV batteries in hybrid energy systems. • Set up of a retired EV battery model considering capacity fade. • Design of a power management strategy for protecting system components. • Set up of a multi-objective optimization model considering energy waste. • Comparison of performance of NSGA-Ⅱ and MOEA/D. Abstract Reusing retired electric vehicle batteries (REVBs) in renewable energy systems is a relatively new concept, and the presented PV-hydrogen-REVB hybrid energy system is a promising way to exploit REVBs' residual capacities. This paper focuses on the design and sizing optimization of the entire system and delivers three main contributions. First, this paper proposes a REVB model based on the model of capacity fading of lithium battery cells, which could allow a more realistic result for the design. Second, a power management strategy is presented to regulate the energy flow, for protecting the REVB and other system components. Third, multiple objectives are considered in the optimization model, including minimizing loss of power supply, system cost, and a new indicator, namely, potential energy waste. Then, using the simulation results of a five-year working period to calculate the objective functions, a multi-objective evolutionary algorithm NSGA-II is applied to generate the Pareto set of a case for residential usage. In further discussions, the influences of ignoring REVB's capacity fading and removing the objective of potential energy waste possibility are presented, as well as the comparison of performances between NSGA-II and MOEA/D. The results reveal that the reliability of the system is impaired if ignoring the REVB's capacity loss, and the proposed indicator is crucial for the design. NSGA-II has a better performance regarding the distribution of solutions and gives better results in this study. [ABSTRACT FROM AUTHOR]

Within this study, the electrochemically inert, molten carbonate fuel cell (MCFC) γ -LiAlO 2 matrix is replaced by oxygen ion conducting ceramics, typical for solid oxide fuel cell (SOFC) application. Such solution leads to synergistic ion transport both by molten carbonate mix (CO 3 2- ) and yttria-stabilized zirconia (YSZ) or samaria-doped ceria (SDC) matrix (O 2- ). Single unit cell tests confirm that application of hybrid ionic membrane increases the performance (power density) of the MCFC over pure γ -LiAlO 2 for a wide range of operating temperatures (600 °C–750 °C). Cell power density with SDC and YSZ matrices is 2% and 13% higher, respectively, compared to the γ -LiAlO 2 at typical 650 °C operating temperature of MCFC. [ABSTRACT FROM AUTHOR]