Fuel Cell Power Plant Research Articles

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.

Development of Solid Oxide Fuel Cells at Versa Power Systems and FuelCell Energy

Versa Power Systems (VPS) is a developer of solid oxide fuel cells (SOFCs) for clean power generation and is a wholly owned subsidiary of FuelCell Energy (FCE). FCE is a global leader in the design, manufacture and distribution of Molten Carbonate Fuel Cell (MCFC) power plants. From an economic perspective, MCFCs scale-up very well and as a result FCE’s MCFC products are in the multi-megawatt size range. SOFCs are complementary because they scale-down well and hence are well suited to sub-megawatt applications. This paper highlights the status of VPS and FCE’s SOFC technology in the areas of cell, stack and system development.

Sensitivity Analysis for the Efficiency Improvement of a Light Integrated Gasification Fuel Cell Power Plant

The solid oxide fuel cell (SOFC) is recognized as one of high efficiency plants of electricity generation for a sustainable future system with low environmental effects. In term of fuel flexibility, SOFC is suitable for direct use of syngas from a coal gasification plant. The application of integrated SOFC in coal gasification based power plant, such as a light integrated gasification fuel cell (L-IGFC) power plant, could be one of the most promising coal energy conversions system providing high electrical efficiency with low CO2 emitted to the atmosphere. The system consists of a coal gasifier and intermediate temperature SOFC module on the top of a steam turbine. The syngas produced by pressurized coal gasifier is used in SOFC module after heat recovery units and cleaning processes. To minimize exergy loses in the plant, the dry gas desulfurization (DGD) unit which can operate at elevated operating temperature and pressure are adopted. The heat generated by SOFC module can be utilized by the heat recovery steam generator providing high quality steam for a steam turbine. In this work, thermodynamic analysis is carried out to develop process integration of the L-IGFC plant. The overall plant analysis of a baseline system design is performed by identifying the major factors effecting plant performance by using the Aspen Plus simulation. The Aspen plus simulation is then used to perform parametric analysis to identify optimum values for the maximum system efficiency. Modifications to the baseline system design are made in order to determine the most viable system designs based on maximizing total system efficiency.

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.

Development of Solid Oxide Fuel Cells at Versa Power Systems and FuelCell Energy

Versa Power Systems (VPS) is a developer of solid oxide fuel cells (SOFCs) for clean power generation and is a wholly owned subsidiary of FuelCell Energy (FCE). FCE is a global leader in the design, manufacture and distribution of Molten Carbonate Fuel Cell (MCFC) power plants. From an economic perspective, MCFCs scale-up very well and as a result FCE’s MCFC products are in the multi-megawatt size range. SOFCs are complementary because they scale-down well and hence are suited to sub-megawatt applications. This paper highlights the status of VPS and FCE’s SOFC technology in the areas of cell, stack and system development.

Sensitivity Analysis for the Efficiency Improvement of a Light Integrated Gasification Fuel Cell Power Plant

The solid oxide fuel cell (SOFC) is recognized as one of high efficiency plants of electricity generation for a sustainable future system with low environmental impact. In term of fuel flexibility, SOFC is suitable for direct use of syngas from a coal gasification plant. The application of integrated SOFC in coal gasification based power plant, such as a light integrated gasification fuel cell (L-IGFC) power plant, could be one of the most promising coal energy conversions system providing high electrical efficiency with low CO2 emitted to the atmosphere. The system consists of a coal gasifier and SOFC module on the top of a steam turbine. The sensitivity analyses of major operating parameters were performed using the developed model. The results indicated that the L-IGFC plant could achieve electrical efficiency in the range of 46.35- 60.32% in lower heating value.

Life cycle analyses of bulk‐scale solid oxide fuel cell power plants and comparisons to the natural gas combined cycle

AbstractIn this work, detailed cradle‐to‐grave life cycle analyses are performed for a current state‐of‐the art natural gas combined cycle and a bulk‐scale solid fuel cell power plant fuelled by natural gas. Life cycle inventories are performed for multiple configurations of each plant, including designs with carbon capture capability. Consistent boundaries (including all supply chain and upstream processes) and unit bases for each process are defined for each process. The ReCiPe 2008 life cycle assessment method is used to quantify the impacts of each plant at both mid‐ and end‐point levels. Three impact assessment perspectives (individualist, hierarchist, and egalitarian) are considered. The results of these life cycle analyses are compared in order to determine the environmental trade‐offs between potential power generation pathways. Results indicate that power generation using solid oxide fuel cells has a smaller life cycle impact than the natural gas combined cycle when the entire life cycle of each option is considered.

Comparative life cycle analyses of bulk-scale coal-fueled solid oxide fuel cell power plants

Detailed cradle-to-grave life cycle analyses are performed for bulk-scale solid oxide fuel cell power plants fueled by gasified coal. These results are compared to cradle-to-grave life cycle analyses of the supercritical pulverized coal and integrated gasification combined cycle power generation plants, which are also performed as a part of this study. Life cycle inventories for each plant including the inputs (resources and fuels) and outputs (emissions and waste) of the gate-to-gate plants and their associated up- and down-stream sub-processes are computed. The impact of carbon capture and sequestration on each plant is quantified and assessed using the ReCiPe 2008 life cycle inventory method for three socioeconomic perspectives. The results of each coal plant are compared to one another and to plants generating power from natural gas at the end-point level. Results indicate that not only do coal-fed SOFCs generate power with a significantly lower life cycle impact than the current state-of-the-art coal plants, but when carbon capture is enabled they can do so with a lower impact than the most modern plants utilizing natural gas, as well.

Efficient and ultra-clean use of biogas in the fuel cell - the DFC experience

FuelCell Energy, Inc. (FCE) in Danbury, CT, currently offers three types of stationary fuel cell power plants: the DFC300, DFC1500, and DFC3000, rated 300, 1,400, and 2,800 kW, respectively, to operate on methane-rich fuels including renewable biogas. These products use the Direct FuelCell® (DFC®), which has the distinctive ability to generate electricity directly from a hydrocarbon fuel by reforming it inside the fuel cell and supplying hydrogen for fuel cell reactions. Biogas, which is available from distributed sources, contains 50% to 70% methane depending on the source and is an exceptionally desired fuel for DFC power plants. FCE has placed many biogas units ranging from 250 kW to 2.8 MW around the world, achieving an electricity conversion efficiency of 45% to 49% (LHV). A unique feature of the DFC is that its performance is not impacted by biofuels diluted with CO2 (20% to 50%). In fact, the DFC plants operating on biogas are consistently showing a higher fuel cell conversion efficiency (approximately 0.5% on a normalized basis) compared to pipeline natural gas plants. This is an advantage as removing CO2 from biogas (as is the case with the ‘directed biogas’) is energy intensive and adds cost. The existing DFC biogas applications focused on wastewater treatment, food processing, and brewery industries where the contaminants are primarily sulfur and siloxanes. FCE has used operational experience with these plants to improve gas supply reliability, understanding of the biogas contaminants, and improvement of removal process effectiveness.

Energy and exergy analysis and optimal design of the hybrid molten carbonate fuel cell power plant and carbon dioxide capturing process

A hybrid molten carbonate fuel cell power plant and carbon dioxide capturing process is investigated through the exergy and advanced exergy analysis. The results show that the greatest exergy destruction (181MW) occurs in the combustion chamber. It is because of irreversibility of the chemical reactions in the combustion process. Also the lowest exergy efficiency is related to the fuel cell. Advanced exergy analysis shows that the most portion of the exergy destruction is avoidable (more than 65%). Optimal design of the process is done by adjusting the effective operating conditions for reducing the power consumption and carbon dioxide emission of the process. Results of the optimization shows that the power consumption in the compressors can be reduced up to 33%.

Conceptual design of light integrated gasification fuel cell based on thermodynamic process simulation

Abstract Integration of solid oxide fuel cell (SOFC) in coal gasification power plant technology would be one of the most promising technology in the coal utilization for power generation. The clean syngas from gas cleanup unit serves as fuel for SOFC in integrated gasification fuel cell power plant. The heat generated by SOFC can be utilized by heat recovery steam generator to drive steam turbine for electricity production. In this study, proposed plants consisting of coal gasifier and SOFC on the top of a steam turbine (ST), called light integrated gasification fuel cell (L-IGFC), are investigated thermodynamically by using Aspen Plus software to evaluate their performance. The analyses are based on the SOFC module considering ohmic, activation and concentration losses at a certain current density of the cell operating at the intermediate temperature. The influences of gas cleanup unit models were also investigated. The results indicated that the proposed atmospheric L-IGFC plant could achieve electrical efficiency in the range of 39–46.35% in lower heating value.

An efficient scenario-based stochastic programming for optimal planning of combined heat, power, and hydrogen production of molten carbonate fuel cell power plants

In this paper, a stochastic model is proposed for planning the location and operation of Molten Carbonate Fuel Cell Power Plants (MCFCPPs) in distribution networks when used for Combined Heat, Power, and Hydrogen (CHPH) simultaneously. Uncertainties of electrical and thermal loads forecasting; the pressures of hydrogen, oxygen, and carbon dioxide imported to MCFCPPs; and the nominal temperature of MCFCPPs are considered using a scenario-based method. In the method, scenarios are generated using Roulette Wheel Mechanism (RWM) based on Probability Distribution Functions (PDF) of input random variables. Using this method, probabilistic specifics of the problem are distributed and the problem is converted to a deterministic one. The type of the objective functions, placement, and operation of MCFCPPs as CHPH change this problem to a mixed integer nonlinear one. So, multi-objective Modified Firefly Algorithm (MFA) and Pareto optimal method are employed for solving the multi-objective problem and for compromising between the objective functions. During the simulation process, a set of non-dominated solutions are stored in a repository. The 69-bus distribution system is used for evaluating the proper function of the proposed method.

ICOPE-15-1054 Experiment and Simulation for Ethanol-Steam Reforming using Cu/ZnO/Al_2O_3 Catalyst

Hydrogen H_2 for fuel-cell power plants is commonly manufactured from hydrogen-rich materials such as hydrocarbons C_nH_m and alcohols C_oH_p(OH)_q, using steam-reforming methods with catalysts. Recently, the authors have investigated the optimum conditions for efficient and endurable steam reforming (Shinoki et al., 2011). Specifically speaking, experiments are conducted with Cu/ZnO/Al_2O_3 catalyst. Using a household-use-scale reactor with well-controlled temperature distribution, the authors have shown that the Cu/ZnO/Al_2O_3 catalyst has rather high performance with high hydrogen concentration C_<H2> at low values of reaction temperature T_R. In the present study, the authors investigate the optimum conditions as well as Shinoki et al., especially focusing on both the influences of liquid-hourly space velocity LHSV upon concentrations such as C_<H2>, C_<CO2>, C_<CO> and C_<CH4> and the influence of LHSV upon the ethanol conversion X_<C2H5OH>, in a wide range of LHSV at several S/C's and at several T_R's. As a result, all the concentrations are close to the theory of Shinoki et al. except for the case at low T_R and high LHSV. To settle the inconsistency of this exceptional case, the authors propose a new theory using some chemical reactions related with acetaldehyde CH_3CHO. Furthermore, the authors discuss the influences of T_R in addition to LHSV.

Performance improvement in grid-connected fuel cell power plant: An LPV robust control approach

Abstract This paper presents a robust control scheme for power electronic interfaces of grid-tied fuel cell power plant. Firstly, a linear matrix inequality (LMI)-based PID controller is designed to control the duty cycle of the boost DC/DC converter, aiming to adjust the output DC voltage to an arbitrary reference value. Afterwards, linear parameter-varying (LPV) technique is utilized for robust control of grid-connected inverter to follow the desired real and reactive power demand of the grid, considering time-varying load and uncertain grid-impedance. Taking uncertainty of the system into account, all admissible variations are considered as a convex polytope. To guarantee a prescribed disturbance attenuation level and improve the transient response of the closed-loop system, H∞ approach is exploited with pole placement consideration in terms of LMIs. Simulation results of the proposed controller compared to those of conventional PI controller, in presence of grid-voltage disturbance, validate high efficiency of the designed control.

Efficient electrochemical refrigeration power plant using natural gas with ∼100% CO2 capture

We propose an efficient Natural Gas (NG) based Solid Oxide Fuel Cell (SOFC) power plant equipped with ∼100% CO2 capture. The power plant uses a unique refrigeration based process to capture and liquefy CO2 from the SOFC exhaust. The capture of CO2 is carried out via condensation and purification using two rectifying columns operating at different pressures. The uncondensed gas mixture, comprising of relatively high purity unconverted fuel, is recycled to the SOFC and found to boost the power generation of the SOFC by 22%, when compared to a stand alone SOFC. If Liquefied Natural Gas (LNG) is available at the plant gate, then the refrigeration available from its evaporation is used for CO2 Capture and Liquefaction (CO2CL). If NG is utilized, then a Mixed Refrigerant (MR) vapor compression cycle is utilized for CO2CL. Alternatively, the necessary refrigeration can be supplied by evaporating the captured liquid CO2 at a lower pressure, which is then compressed to supercritical pressures for pipeline transportation. From rigorous simulations, the power generation efficiency of the proposed processes is found to be 70–76% based on lower heating value (LHV). The benefit of the proposed processes is evident when the efficiency of 73% for a conventional SOFC-Gas turbine power plant without CO2 capture is compared with an equivalent efficiency of 71.2% for the proposed process with CO2CL.

Modeling of a solid oxide fuel cell power plant using an ensemble of neural networks based on a combination of the adaptive particle swarm optimization and Levenberg–Marquardt algorithms

In this paper, a dynamic nonlinear model of a Solid Oxide Fuel Cell (SOFC) is determined using an ensemble of Neural Networks (NNs). The Component NNs (CNNs) of the ensemble are trained using the Levenberg–Marquardt (LM) algorithm. The ensemble of NNs is optimized using the hybrid adaptive Particle Swarm Optimization (PSO) with a newly developed Negative Correlation Learning (NCL) method. In this work, PSO has been used to pre-train CNNs before the LM algorithm is employed. In this way, we will get rid of the shortcomings of both of these two methods; PSO has a global vision but it cannot find the global minimum precisely while LM can generally find this minimum but needs a good starting point near the global minimum. An ensemble of NNs shows greater generalization performance compared to a single neural network. In NCL, all the CNNs in the ensemble are trained simultaneously and interactively using the correlation penalty terms in their error functions. Instead of constructing unbiased individual networks whose errors are uncorrelated, NCL can generate negatively correlated networks to boost specialization and cooperation among the individual networks. NNs are excellent tools to model complex nonlinear dynamic systems and can be useful for simulation of SOFC. The results indicated that the SOFC outputs can be accurately estimated using the trained model in this work.

The carbonate fuel cell—concept to reality

The high temperature carbonate fuel cell is an ultraclean and high efficiency power generator. Its operating temperature, ∼550–650°C, is considered optimum to facilitate fast reaction kinetics, utilize waste heat efficiently, and at the same time allow use of commercial commodity construction materials and well‐established manufacturing processes which permit cell construction in large sizes. Also, the carbonate fuel cell can be equipped with the unique capability to generate hydrogen within the fuel cell from a hydrocarbon fuel allowing a simpler power plant system design. Because of these favorable attributes, the carbonate fuel cell is leading commercial deployment for clean distributed power. The carbonate fuel cell power plants are currently available in the size ranges 350 kW, 1.4 MW, and 2.8 MW. These plants are installed at numerous locations worldwide and have delivered 2.0 GWh of ultraclean electricity (as of mid‐December, 2013). Carbonate fuel cell technology and product status is described in this article. WIREs Energy Environ 2015, 4:178–188. doi: 10.1002/wene.124This article is categorized under: Fuel Cells and Hydrogen &gt; Science and Materials

Impacts of reforming energy subsidies on small scale generator business in Iran

Iran had been dedicating a substantial amount of its budget, known as subsidy, to keep the price of natural gas and electricity for customers considerably lower than real cost until 2011. Legislatures passed a law reforming energy subsidy in 2011, but this process is to take five years. Iran ceased to fully-subsidize from 2011, and gradually continues this process through 2015 when no subsidy will be paid. After 2015, the energy price will reach its prime cost. In addition, Tavanir organization, official organization of electrical energy management, published the “contract of guaranteed purchase price of energy for small scale generator”. Based on the contract, the Ministry of Energy guaranties that electricity generated by a small scale generator is purchased at a price higher than market purchase price (http://www.tavanir.org.ir: letter no. 52504/350, October 22, 2008). These two issues, reforming subsidies and incentives for small scale generators' owners, would affect distributed generation areas in terms of operation and investment. This research studies effects of reforming energy subsidy on optimum daily operation of a Fuel Cell Power Plant (FCPP), as an example; however, the results are not only helpful for FCPP but also extendable to some extent to other small scale distributed generators.

Fuzzy Logic Based Controller for a Grid-Connected Solid Oxide Fuel Cell Power Plant.

This paper describes a mathematical model of a solid oxide fuel cell (SOFC) power plant integrated in a multimachine power system. The utilization factor of a fuel stack maintains steady state by tuning the fuel valve in the fuel processor at a rate proportional to a current drawn from the fuel stack. A suitable fuzzy logic control is used for the overall system, its objective being controlling the current drawn by the power conditioning unit and meet a desirable output power demand. The proposed control scheme is verified through computer simulations.

Control and Operation Of a Solid Oxide Fuel-Cell Power Plant In an Isolated System

Control and Operation Of a Solid Oxide Fuel-Cell Power Plant In an Isolated System