Oxide Fuel Cell Power Plant Research Articles

Solid oxide fuel cell energy system with absorption-ejection refrigeration optimized using a neural network with multiple objectives

The present study focuses on modeling the solid oxide fuel cell power plant combined with an absorption-ejection refrigeration cycle. First, a comparison is made between the absorption chiller refrigeration cycle and the absorption-ejection chiller to connect the superior cycle to the solid oxide fuel cell as an auxiliary cycle. Then, the solid oxide fuel cell cycle, the combustion of the output product, the heat recovery unit combined with the refrigeration cycle, and freshwater production are modeled. Next, the sensitivity analysis is presented in order to study the effect of the design parameters on objective functions, which simplifies the justification of the optimization results based on the genetic algorithm. In order to perform optimization, machine learning methods have been employed to reduce computational time and cost. The optimization of this cycle shows that the exergy efficiency is enhanced up to 68%, whereas the overall cost rate is in within 9.7–10.4 dollars per hour.

Simulation and 4E analysis of a novel coke oven gas-fed combined power, methanol, and oxygen production system: Application of solid oxide fuel cell and methanol synthesis unit

To address an innovative trigeneration process using coke oven gas as the input fuel, a novel heat integration process based on a solid oxide fuel cell is designed and discussed in the current research. Since the coke oven gas is a hydrogen-enriched fuel, its application in a solid oxide fuel cell power plant can improve sustainability and environmental indexes. The flue gas leaving the fuel cell subsystem is directed to a Kalina power cycle and an absorption power cycle for heat recovery, wherein additional power is available. Accordingly, the rejected flue gas is sent into a methanol synthesis unit for producing methanol. A part of generated electric power is delivered to a proton electrolyte membrane electrolyzer, where the water electrolysis process generates hydrogen and oxygen. Here, the generated hydrogen is delivered to the methanol synthesis unit. This system is simulated in the Aspen HYSYS software. To study the designed system, energy, exergy, environmental, and economic assessments are considered. In addition, a sensitivity study based on the main variables is performed. According to the results, the energy and exergy efficiencies of the whole structure are 34.69% and 88.885, respectively. In addition, the methanol production cost was 0.595 $/kg. The CO2 emission intensity is found to be 0.18 kgCO2/kgMeOH. So, the use of coke oven gas reduced the environmental threats considerably.

Performance Assessment of the Heat Recovery System of a 12 MW SOFC-Based Generator on Board a Cruise Ship through a 0D Model

The present work considers a 12 MW Solid Oxide Fuel Cell (SOFC) power plant integrated with a heat recovery system installed on board an LNG-fuelled cruise ship of about 175,000 gross tonnes and 345 m in length. The SOFC plant is fed by LNG and generates electrical power within an integrated power system configuration; additionally, it provides part of the thermal energy demand. A zero-dimensional (0D) Aspen Plus model has been built-up to simulate the SOFC power plant and to assess the performances of the proposed heat recovery system. The model has been validated by comparing the results obtained with data from the literature and commercial SOFC modules. The integrated system has been optimized in order to maximize steam production since it is the most requested thermal source on board. The main design outcome is that the steam produced is made by the recovered water from the SOFC exhaust by about 50–60%, thus reducing the onboard water storage or production. Additionally, results indicate that such an integrated system could save up to about 14.4% of LNG.

A novel hybrid process with a sustainable auxiliary approach concerning a biomass-fed solid oxide fuel cell and triple-flash geothermal cycle

Designing a multi-source system provides a higher performance from energy and economic viewpoints. Hence, an innovative two-part hybrid process with a sustainable auxiliary approach is proposed. The first part relies on a solid oxide fuel cell power plant feeding biomass fuel, and the second one utilizes a triple-flash geothermal cycle equipped with a domestic water heater, an ejector refrigeration cycle, and a water electrolysis unit responding to some urban utilities. The proposed system is analyzed from the energy, exergy, economic, and environmental standpoints. Besides, a multiple objective optimization is considered in four different scenarios to identify the most suitable optimum state. The system produces 3853 kW net power, 2158 kW cooling load, 1588 kW heating load, and 0.36 kg/h hydrogen, leading to 59.92% exergetic efficiency and 16.68 M$ net profit at the base condition. Accordingly, the steam turbines have the highest cost rate, and the ejector contains the highest exergy destruction rate. Also, the SOFC current density significantly impacts the total exergetic efficiency and exergy destruction rate. Eventually, the exergy-environmental scenario represents the best optimum state in which the exergetic efficiency, levelized total emission, and net profit are achieved at 64.82%, 0.2 ton/MWh, and 17.38 M$, respectively.

Power Quality Diagnosis Due to Integration of Renewable Energy Source at Utility Grid

Article outlines hybrid energy sources for fulfil supply demand through proposed approach. The hybrid renewable energy sources generation capacity of 6 kW as solar power and 50 kW power as solid oxide fuel cell plant with storage system are interfaced to the DC bus in proposed paper for performance diagnosis on the basis of power demand as per utility load application by conversion of DC power to AC power and power quality of grid/load parameters collected on PCC, which affected by RE source integration at utility bus in terms of power quality parameters as per event ON/OFF grid mode. For this study design a two-bus test system, first bus is DC bus for integration of solar PV plant and solid oxide fuel cell power plant to generate hybrid DC power which convert to AC power by using inverter technology and deliver to the second bus of utility load bus in proposed test system for application of utility load as well as utility grid as per event proposed. A low pass LC filter is modeled to remove high frequency harmonics from the inverter output which is fed to grid as well as test system of utility network.

Thermo-environmental multi-aspect study and optimization of cascade waste heat recovery for a high-temperature fuel cell using an efficient trigeneration process

This study suggests a novel cascade waste heat recovery process for a solid oxide fuel cell power plant. The present process utilizes a trigeneration model producing electricity, cooling, and hydrogen using the energetic stream exiting the upper power plant. This model consists of a two-stage steam Rankine cycle, an ejector refrigeration cycle, a thermoelectric generator, and a low-temperature electrolyzer. After precise thermal and electrochemical simulations, a multi-aspect sensitivity analysis is regarded from the thermo-environmental point of view. Afterward, a multi-objective optimization procedure is applied through the non-dominated sorting genetic algorithm-II. The main difference between the present model and those evaluated in the literature review is its combined cooling and power cycle, which significantly increases the overall performance. According to the sensitivity analysis, the fuel cell operating temperature is the most crucial parameter affecting the studied variables. From the optimization, the optimum objective functions, i.e., exergy efficiency and carbon dioxide emission, are found to be 58.02 % and 252.5 kg/MWh, respectively. In addition, the optimum net generated power, cooling output, and hydrogen production rate are computed to be 508.8 kW, 161.9 kW, and 0.6 kg/h, respectively. Besides, the optimum energy efficiency and exergoenvironmental impact index are equal to 68.2 % and 0.7, respectively.

Life cycle assessment shows that retrofitting coal-fired power plants with fuel cells will substantially reduce greenhouse gas emissions

Life cycle assessment shows that retrofitting coal-fired power plants with fuel cells will substantially reduce greenhouse gas emissions

Biodiesel production integrated with glycerol steam reforming process, solid oxide fuel cell (SOFC) power plant

Process of biodiesel production integrated with glycerol steam reforming process, solid oxide fuel cell power plant, and also the organic Rankine cycle for the simultaneous production of biodiesel and electricity is investigated. In the biodiesel production scenario, biodiesel is obtained from waste cooking oil using acid catalyst coupled with hexane extraction. The glycerol obtained from the above method is subjected to steam reforming process to produce hydrogen. The hydrogen produced is then used as fuel in the solid oxide fuel cell to provide thermal and electrical energy for biodiesel production and reforming processes. In addition, generating extra power will allow biodiesel production to be more economical by injecting it into the electricity network. It also provides the heat duty of organic Rankine cycle. Sensitivity analysis is accomplished on the proposed model to indicate the effects of several parameters on the biodiesel production, glycerol production, power generation, and process efficiency. This study showed that with increasing oil flow rate, total generated power in SOFC, SOFC cycle efficiency, input flow to fuel cell and cell number decreased. Also, with increasing the fuel utilization coefficient, electrical efficiency, cell number, total output power from SOFC and overall thermal efficiency increased. The effect of inlet heat to distillation towers on parameters such as overall thermal efficiency and electrical efficiency and total generated power was also investigated. As main results, solid oxide fuel cell efficiency, Electrical efficiency, and overall thermal efficiency based on LHV are 25.09%, 28.14%, and 85.16%, respectively. Overall, developing a biodiesel production plant by upgrading glycerol to hydrogen through steam reforming and using hydrogen produced in solid oxide fuel cell and employing organic Rankine cycle to generate power is an attractive strategy to make biodiesel production cycles more economical.

Методика расчёта режимов электрохимических энергоустановок с твёрдооксидным электролитом

Fuel cell power plants (FCPPs) are considered as one of the key future energy technologies. Along with machine-based power generation technologies (gas turbine units, diesel generator sets, combined cycle plants, Stirling engine plants, etc.), FCPPs can also be used in cogeneration plants for combined generation of electricity and heat. Fuel cells can find use in Russia for distributed electricity generation, including autonomous power supply to consumers based on the use of pipeline and liquefied natural gas, liquefied hydrocarbon gases, as well as renewable energy sources, especially in cogeneration modes of operation. A procedure for calculating the operation modes of a fuel cell power plant is proposed, assuming that the combustible elements contained in the fuel are fully oxidized, transforming into inert gases. The flowrates of products before and after the reactions at the FCPP inlet and outlet are determined by using the material balance method. The material and energy balances of fuel cells are calculated taking as an example an SOFC-type FCPP with a solid oxide electrolyte for direct internal conversion of methane and also during operation on pure hydrogen in a combination with a windmill. The possibility of storing energy in hydrogen storage devices is estimated. In view of their highest electric and cogeneration efficiencies, solid oxide FCPPs using natural gas (methane) as fuel (reducing agent) and atmospheric oxygen (air) as oxidizer are considered to be promising ones for cogeneration-type electric power sources. The required methane and air flowrates are determined assuming that the oxygen content in air is equal to 21%. The potential fuel capacity was calculated for the installation’s electric power equal to 15 MW and its heat load in the cogeneration mode equal to 6 MW. This thermal power is removed from the FCPP fuel cell unit through a delivery water heater for its further use. The hydrogen storage device can be made as a gas tank or a gas cylinder. Obviously, pressurized gaseous hydrogen storing systems are simple and do not require special equipment for retrieving gas from the storage.

Voltage control of solid oxide fuel cell power plant based on intelligent proportional integral-adaptive sliding mode control with anti-windup compensator

Solid oxide fuel cell (SOFC) plant is considered a most important type in the field of fuel cells, which gives control difficulties such as fuel flow constraints, load disturbance, system nonlinearities, and parameter uncertainties. However, due to these difficulties, the voltage control of SOFC plant is extremely difficult. In this paper, a new intelligent proportional integral-adaptive sliding mode control (iPI-ASMC) with anti-windup compensator is proposed to control the output voltage of SOFC plant to keep up with the rated voltage. The referred iPI-ASMC is made of three sub-components: (i) an extended state observer (ESO)-based-intelligent proportional-integral to estimate the unknown dynamic, (ii) an adaptive sliding mode control is added to compensate the estimation error of unknown dynamic, and (iii) an anti-windup compensator based on back-calculation is used to deal with saturation problem which is caused by input constraints. Moreover, the effectiveness and efficiency of the proposed iPI-ASMC strategy is demonstrated by comparing with some other approaches such as conventional proportional integral-derivative (PID) controller, intelligent proportional-integral (iPI) and fuzzy PID controller. Corresponding simulation results show that the proposed iPI-ASMC approach provides better dynamic responses and outperforms to compared methods in term of settling time, peak overshoots, integral absolute error (IAE), integral square error (ISE), and integral time absolute error (ITAE).

EXPERIENCE OF AVL AND NISSAN COMPANIES IN APPLICATION OF SOFC POWER PLANTS AS RANGE EXTENDERS FOR ELECTRIC LIGHT VEHICLES

In previous manuscripts we considered perspective of application of power plants based on solid oxide fuel cells (SOFC) as auxiliary power units for heavy truck automobile transport: we considered USA and European experience. High level of this technology promises was shown with description of economical and technical data. In current paper we consider the first world experience of SOFC power plant application as a range extender for electrical cars. This project was implemented by consortium of Austrian company «AVL» and «Nissan». Described light vehicle was developed and constructed to be demonstrated during summer Olympic games in 2016 in Rio (Brazil). Bio-ethanol manufactured from natural sources was used as a fuel for solid oxide fuel cell power plant. Constructed vehicle was equipped with lithium-ion battery pack as primary power source, solid oxide fuel cell power plant with power output of 5 kW was used as range extender to enlarge the range of vehicle in a way of battery recharge during operation and discharge due to road motion. This light vehicle was tested in road conditions. Range of trip using only lithium-ion battery pack was measured on a level of 120 km, introduction of solid oxide fuel cell power plant gave opportunity to extend this value up to about 600 km – in 5 times. Startup time of SOFC power plant described in this work was showed on level of about 40 min which is good enough for this application as solid oxide fuel cell power plant is not a primary power source and vehicle can start motion before start of SOFC system using batteries energy. These data obviously show high advantages of introduction of such system of battery pack with solid oxide fuel cell range extender in light vehicles. Keywords: automobile transport; car; solid oxide fuel cells; SOFC; power plant; range extender; electrical car.

Optimal Design of Proportional–Integral Controllers for Grid-Connected Solid Oxide Fuel Cell Power Plant Employing Differential Evolution Algorithm

This paper proposes the application of differential evolution (DE) algorithm for the optimal tuning of proportional–integral controller designed to improve the small signal dynamic response of a grid-connected solid oxide fuel cell (SOFC) system. The small signal model of the study system is derived and considered for the controller design as the target here is to track small variations in SOFC load current. The proposed proportional–integral (PI) controllers are incorporated in the feedback loops of hydrogen and oxygen partial pressures, grid current d–q components and dc voltage with an aim to improve the small signal dynamic responses. The controller design problem is formulated as the minimization of an eigenvalue-based objective function where the target is to find out the optimal gains of the PI controllers in such a way that the discrepancy between the obtained and desired eigenvalues is minimized. Eigenvalue and time domain simulations are presented for both open-loop and closed-loop systems. To test the efficacy of DE over other optimization tools, the results obtained with DE are compared with those obtained by particle swarm optimization (PSO) algorithm and invasive weed optimization (IWO) algorithm. Three different types of load disturbances are considered for the time domain-based results to investigate the performances of different optimizers under different sorts of load variations. Moreover, nonparametric statistical analyses, namely one-sample Kolmogorov–Smirnov (KS) test and paired sample t test, are used to identify the statistical advantage of DE algorithm over the other two. The presented results suggest the supremacy of DE over PSO and IWO in finding the optimal solution.

Renewed sanitation technology: A highly efficient faecal-sludge gasification–solid oxide fuel cell power plant

Sustainable development goals for 2030 aim at the extensive reduction of the global sanitation breach; this might be achieved by renewed sanitation technologies and while providing sanitation recover valuable products such as energy. Consequently, this work presents a gasification–solid oxide fuel cell (SOFC) power plant that was configured for high-efficiency energy recovery from faecal sludge. The main limitations of faecal sludge gasification are the production of impurities, such as tar, and the high energy requirements for both the endothermic gasification process and removing the high moisture content in the feedstock. However, results from this work indicate that a superheated steam dryer combined with an indirectly heated multistage gasifier and a gas-cleaning unit can overcome the mentioned limitations. The external heat for the gasifier is supplied by the process heat available and a microwave plasma torch, and there is sufficient heat to drive a micro steam turbine. Thermodynamic calculations indicated that the plant could reach a net electrical efficiency of the order of 65%. As a result, a gasification–SOFC power plant is more suitable for energy recovery than any other process such as biochar production by pyrolysis; hence, it might become a technology that is financially feasible and can be used globally for sanitation purposes.

FuelCell Energy SOFC unit for NRG Energy Center in Pittsburgh

The NRG Energy Center in Pittsburgh, Pennsylvania will host a solid oxide fuel cell power plant developed by Connecticut-based FuelCell Energy under a previously awarded US Department of Energy contract. The power plant will deliver energy to the NRG Yield facility, which provides heating and cooling for commercial and residential facilities in downtown Pittsburgh.

Thermodynamic analysis of biogas fed solid oxide fuel cell power plants

The present research study presents the optimization of Solid Oxide Fuel Cell (SOFC) power plants directly fed by biogas. By considering energy and exergy balances for such a system, a detailed thermodynamic model (THERMAS) was designed and implemented. A specific SOFC-based system was selected as case study, equipped with three heat exchangers (preheaters), a reformer, a SOFC-stack system and an afterburner. The use of the simulation tool THERMAS give us the opportunity to investigate all the appropriate parameters that affect system’s efficiency based on exergy analysis while incorporating a detailed parametric analysis regarding the whole system. The optimization process relies on the difference between the energy and exergy efficiency by considering an innovative Optimization Factor (OPF) for each simulated system, which is dynamically affected by operational parameters, such as fuel composition, extension of chemical reactions and temperatures. It is found that the use of a pure fuels seems to be meaningless without optimization.

Input–Output Linearization-Based Controller Design for Stand-Alone Solid Oxide Fuel Cell Power Plant

Application of input–output linearization control for improving the dynamic response of a stand-alone solid oxide fuel cell (SOFC) system is presented in this work. The proposed controllers are incorporated in the study system to eliminate the sluggishness in the hydrogen and oxygen partial pressure responses due to variations in the SOFC reference current. Temperature dynamics of SOFC is taken into consideration to replicate the impact of temperature variation on the system dynamics. Eigenvalue study of the linearized zero dynamics is conducted to determine the stability of the unobservable part of the system, and the remaining dynamics is considered for designing the input–output linearization-based controllers. Pole placement technique is adopted to obtain the controller gains which give the desired dynamic response. The performance of the proposed technique is compared with that of the optimized proportional–integral (PI) controller. The proposed controller efficiency is also tested under varying operating conditions and measurement noise. Simulation results show the efficacy and supremacy of the proposed method in improving the dynamic response of the study system.

Optimal design of proportional-integral controllers for stand-alone solid oxide fuel cell power plant using differential evolution algorithm.

This paper proposes the application of differential evolution (DE) algorithm for the optimal tuning of proportional–integral (PI) controller designed to improve the small signal dynamic response of a stand-alone solid oxide fuel cell (SOFC) system. The small signal model of the study system is derived and considered for the controller design as the target here is to track small variations in SOFC load current. Two PI controllers are incorporated in the feedback loops of hydrogen and oxygen partial pressures with an aim to improve the small signal dynamic responses. The controller design problem is formulated as the minimization of an eigenvalue based objective function where the target is to find out the optimal gains of the PI controllers in such a way that the discrepancy of the obtained and desired eigenvalues are minimized. Eigenvalue and time domain simulations are presented for both open-loop and closed loop systems. To test the efficacy of DE over other optimization tools, the results obtained with DE are compared with those obtained by particle swarm optimization (PSO) algorithm and invasive weed optimization (IWO) algorithm. Three different types of load disturbances are considered for the time domain based results to investigate the performances of different optimizers under different sorts of load variations. Moreover, non-parametric statistical analyses, namely, one sample Kolmogorov–Smirnov (KS) test and paired sample t test are used to identify the statistical advantage of one optimizer over the other for the problem under study. The presented results suggest the supremacy of DE over PSO and IWO in finding the optimal solution.

Exergoeconomic evaluation of an ethanol-fueled solid oxide fuel cell power plant

A SOFC (solid oxide fuel cell) system integrated with an ethanol steam reforming unit is evaluated using exergoeconomic analysis. The exergy destruction cost, total production cost, relative cost difference, exergoeconomic factor and thermoeconomic cost of electricity are studied. The TCOE (thermoeconomic cost of electricity) is compared with electricity cost from similar processes and fuels. A sensitivity analysis has been carried out in order to have a good insight into SOFC power plant performance, focusing on ethanol steam reformer temperature (823 < TESR < 973 K), SOFC stack unit cost (1500–400 $ kW) and fuel price (0.002 < ethanol price < 0.01 $ MJ−1). Results suggest that the SOFC unit constitutes the most important component in the process. A reduction in the investment cost and in exergy destruction within the stack may reduce the total production cost (Ctot), total investment costs (Ztot) and exergy destruction cost (CD) by 18%, 73% and 19% respectively, as well as the electricity cost (TCOE) by 21%. The higher production cost corresponds to higher ethanol price, due to the specific exergy cost of streams. In the best scenario, the electricity cost using ethanol as feedstock reaches 0.04 $ kWh−1, which is comparable and competitive with natural gas (0.06 $ kWh−1) using SOFC technology.

Thermodynamic and exergoeconomic analysis of biogas fed solid oxide fuel cell power plants emphasizing on anode and cathode recycling: A comparative study

Four different configurations of natural gas and biogas fed solid oxide fuel cell are proposed and analyzed thermoeconomically, focusing on the influence of anode and/or cathode gas recycling. It is observed that the net output power is maximized at an optimum current density the value of which is lowered as the methane concentration in the biogas is decreased. Results indicate that when the current density is low, there is an optimum anode recycling ratio at which the thermal efficiency is maximized. In addition, an increase in the anode recycling ratio increases the unit product cost of the system while an increase in the cathode recycling ratio has a revers effect. For the same working conditions, the solid oxide fuel cell with anode and cathode recycling is superior to the other configurations and its thermal efficiency is calculated as 46.09% being 6.81% higher than that of the simple solid oxide fuel cell fed by natural gas. The unit product cost of the solid oxide fuel cell-anode and cathode recycling system is calculated as 19.07$/GJ which is about 35% lower than the corresponding value for the simple natural gas fed solid oxide fuel cell system.

Large size biogas-fed Solid Oxide Fuel Cell power plants with carbon dioxide management: Technical and economic optimization

This article investigates the techno-economic performance of large integrated biogas Solid Oxide Fuel Cell (SOFC) power plants. Both atmospheric and pressurized operation is analysed with CO2 vented or captured. The SOFC module produces a constant electrical power of 1 MWe.Sensitivity analysis and multi-objective optimization are the mathematical tools used to investigate the effects of Fuel Utilization (FU), SOFC operating temperature and pressure on the plant energy and economic performances. FU is the design variable that most affects the plant performance. Pressurized SOFC with hybridization with a gas turbine provides a notable boost in electrical efficiency. For most of the proposed plant configurations, the electrical efficiency ranges in the interval 50–62% (LHV biogas) when a trade-off of between energy and economic performances is applied based on Pareto charts obtained from multi-objective plant optimization. The hybrid SOFC is potentially able to reach an efficiency above 70% when FU is 90%. Carbon capture entails a penalty of more 10 percentage points in pressurized configurations mainly due to the extra energy burdens of captured CO2 pressurization and oxygen production and for the separate and different handling of the anode and cathode exhausts and power recovery from them.