Stationary Fuel Cell Systems Research Articles

Comprehensive Review on Fuel Cell Technology for Stationary Applications as Sustainable and Efficient Poly-Generation Energy Systems

Fuel cell technologies have several applications in stationary power production, such as units for primary power generation, grid stabilization, systems adopted to generate backup power, and combined-heat-and-power configurations (CHP). The main sectors where stationary fuel cells have been employed are (a) micro-CHP, (b) large stationary applications, (c) UPS, and IPS. The fuel cell size for stationary applications is strongly related to the power needed from the load. Since this sector ranges from simple backup systems to large facilities, the stationary fuel cell market includes few kWs and less (micro-generation) to larger sizes of MWs. The design parameters for the stationary fuel cell system differ for fuel cell technology (PEM, AFC, PAFC, MCFC, and SOFC), as well as the fuel type and supply. This paper aims to present a comprehensive review of two main trends of research on fuel-cell-based poly-generation systems: tracking the market trends and performance analysis. In deeper detail, the present review will list a potential breakdown of the current costs of PEM/SOFC production for building applications over a range of production scales and at representative specifications, as well as broken down by component/material. Inherent to the technical performance, a concise estimation of FC system durability, efficiency, production, maintenance, and capital cost will be presented.

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Proton-conducting Ceramic Fuel Cells for Co-Producing Electricity and Fuel – A Design for Manufacture and Assembly (DFMA) Analysis

This work develops preliminary design for manufacture and assembly (DFMA) models of a novel, proton-conducting, anode-supported ceramic electrochemical cell for co-producing electricity and fuels simultaneously. These DFMA models can then be used to estimated future, expected costs incorporating the novel cell design under various manufacturing production scenarios. The cell electrochemically coverts oxygen (O2) in air and methane (CH4) fuel (the primary constituent of natural gas) into electricity, water, and higher-order hydrocarbons, such as ethane (C2H6). To do this, the cell integrates a methane coupling catalyst into the anode and thereby co-produces ethane (C2H6) and hydrogen (H2) at the anode. The ethane can then be converted into other fuels. The cell is part of a joint R&D effort by Argonne National Laboratory (ANL) and the Illinois Institute of Technology (IIT). The cell’s current technology readiness level (TRL) is about a one (1), i.e. laboratory-scale demonstration of the fundamental concept.Approach:Gaia Energy Research Institute (Gaia) collaborates closely with ANL and IIT to develop the DFMA models for this novel cell design. Gaia works closely with ANL and IIT to identify and analyze key electrochemical cell engineering performance data. Gaia then develops and deploys custom DFMA computer models and data sets. DFMA models center around the electrolyte-electrode assembly (EEA), or the ‘heart’ of the electrochemical cell, where the anode and cathode half-reactions occur. Gaia first develops a specific physical embodiment of the novel cell, then the cell’s bill of materials (BOM), and finally cost estimates for the electrochemical cell, fuel cell stack, and full-scale stationary fuel cell system. Gaia follows this methodology:1. Develop a specific design that physically embodies the EEA concept;2. Develop the EEA’s BOM to specify quantities of components and materials used;3. Identify, for all key materials, price quotes from one or more manufacturers;4. Calculate the minimum costs for the EEA based on materials costs alone;5. Ascertain the EEA’s primary cost drivers;6. Quantify the uninstalled capital costs for a full-size fuel cell stack and stationary fuel cell system incorporating the novel cell design.With the exception of the EEA, other parts of the fuel cell, stack, and system were assumed to be somewhat similar in design to more traditional stationary solid oxide fuel cell (SOFC) systems. Capital costs for the novel stack design were scaled linearly with stack power density. This work estimates stack and system costs for a 100 kWe net electric stack mass-produced at a rate of 50,000 systems per year.Results:Model results indicate that the fuel cell stack subsystem will cost about $478/kW and the entire fuel cell system will cost about $597/kW, including all BOP components. These stack costs are roughly 74% higher than a ‘plain vanilla’ SOFC subsystem, analyzed by the author for DOE in a prior analysis. These system costs are roughly 48% higher than the same ‘plain vanilla’ SOFC system previously analyzed. At the same time, these cost estimates are well below the DOE ARPA-E program goal of < $2,000/kW.Gaia observed an order of magnitude difference in price quotes for several of the specialty ceramic materials investigated. Price quotes from Praxair Specialty Ceramics were approximately double those of Trans-Tech Inc. The reasons cited for the extreme price differential were different manufacturing methods, specifically a chemical co-processing approach for Praxair and a solid-state material manufacturing process (SSMP) for Trans-Tech Inc. The pros and cons of each manufacturing approach are discussed in greater detail in this talk. This analysis assumes that SSMP is used with no degradation in cell performance and bases subsequent cost estimates solely on prices from Trans-Tech Inc., and not Praxair, at ANL’s request.The primary cost driver for the EEA appears to be the BZY-NiO anode substrate. The BZY and NiO anode substrate material is estimated to cost either 2.88 cents/cm2 [based on price quotes for BZY from TransTech Inc.] or 16.40 cents/cm2 [based on price quotes from Praxair Specialty Ceramics]. If the lower BZY cost estimate is taken based on price quotes from Trans-Tech Inc., 52% of the cost derives from the BZY. If the higher BZY cost estimate is taken based on price quotes from Praxair Specialty Ceramics Inc., 92% of the cost derives from the BZY. The secondary cost driver for the EEA appears to be the anode catalyst. The catalyst material is estimated to cost 2.45 cents/cm2. 94% of its cost is due to the material cost of the platinum. The EEA is estimated to cost 5.56 cents/cm2 or $278/kW of gross electric power from the cell or stack.

Evaluation of Modular Solid Oxide Fuel Cell Systems for Providing Resiliency to Data Centers and Other Critical Power Users

Aris Energy Solutions, LLC and its project partners, Gaia Energy Research Institute (Gaia), the National Energy Technology Laboratory, the University of West Virginia, Velocity Data Centers, and the National Aeronautics and Space Administration are installing and testing next-generation, modular SOFC systems at data centers, and Gaia is spearheading the effort to independently analyze the engineering and economic performance of these systems, benchmarked against DOE’s performance and price compression goals. This work develops thermodynamic and techno-economic analyses (TEA) for these modular SOFC systems and initially focuses on identifying cost drivers critical to their R&D and commercialization path.Approach:Gaia completes a TEA based on experimentally-measured test data from the installed SOFC systems. Gaia collaborates with the project Team to identify and analyze cell, stack, and system engineering performance data. Gaia then develops and deploys custom computer models and data sets that include, but are not limited to, design for manufacture and assembly (DFMA) models of the modular SOFC systems. This TEA includes detailed cell and stack costs, costs of balance of plant (BOP) components, capital costs, operating and maintenance costs (fixed and variable), and sensitivity analyses. Modelling results initially focus on identifying primary cost drivers.Results:Modelling results indicate that the primary cost drivers for the lifecycle costs of these modular SOFC systems include, but are not limited to,(1) the system’s ramp rate (i.e. the system’s ability to change its electric power output up and down per unit time);(2) the in-use, experimentally-measured electrical efficiencies of the stack, BOP subsystem components, and overall system;(3) the system’s availability (i.e. the percentage of time that the system is up and running)(4) the power density of the stack;(5) the capital costs of the stack;(6) the capital costs of the surrounding BOP subsystems;(7) the quantity of effective, in-use heat recovery when operated in combined heat and power (CHP) mode.Regarding (1), when connected to data centers and to the electricity grid, these SOFC systems need to have the ability to rapidly increase or decrease their electrical power output. The modular SOFC systems tested here have been specifically designed with a high degree of electrical ramping capability over a high turn-down ratio. In a data center, this fast-ramping capability enables the modular SOFC systems to more closely follow the data center’s load, which is the most valuable end-use of the electricity, while limiting electricity exported to the grid, which is typically less lucrative and highly dependent on regional legislation that impacts a distributed generator’s access to sell back electricity to the grid and the ‘sell back price.’Regarding (2), historically, the actual, measured in-use electrical efficiencies of stationary fuel cell systems installed in the field have strayed substantially from manufacturer specifications. The extent of this discrepancy has varied substantially, depending on the specific manufacturer, the cell technology, operating conditions, the usage profile, the age of the system, and other factors. Yet, the lifecycle costs are heavily influenced by this actual, measured in-use electrical efficiency; this variable encapsulates the quantity of natural gas/ energy consumed vs. the quantity of electricity produced. The value proposition of these systems is heavily determined by this efficiency, combined with the spark spread, or the difference between the natural gas purchase price and the price / value of the otherwise displaced electricity.Regarding (3), electricity at data centers and other critical power users demands a financial premium, in part due to an expectation of increased uptime (or reduced downtime) of the electricity supplied. To warrant this financial premium, the SOFC systems must demonstrate a high availability, defined as the percentage of time that the system is able to remain up and running at or above its baseline engineering performance standards (including, for example, its electrical efficiency, its electrical power output, etc.)Regarding (4), (5), and (6), primary cost drivers for the modular SOFC systems also include stack capital costs, stack power density, and system BOP costs. Over time, stack capital costs are estimated to decline more rapidly with more high-volume manufacture, compared with BOP capital costs, because the BOP already incorporates many mass-produced components.Regarding (7), these modular SOFC systems are also unique in that they can supply their waste heat at high enough temperatures to be useful for space and hot water heating in most U.S. and European buildings. Unlike other modular fuel cell predecessors, these SOFC systems can integrate well with the existing heating systems of most buildings, based on their heat supply temperatures and the heat demand temperatures prevalent in most building types. Figure 1

Mechanical properties of a wide range of pipe steels under influence of pure hydrogen or hydrogen blended with natural gas

Hydrogen economy considers hydrogen as a substantial fraction of a nation's energy and services. This could happen in the future if hydrogen can be produced from domestic energy sources economically and in an environmental-friendly manner.Hydrogen can also be used as fuel in stationary fuel cell systems for buildings, emergency power or distributed generation. Hydrogen transport is generally made by pipelines. This solution is preferable than transport on road by truck for security reasons.The addition of hydrogen in natural gas could have an impact on the materials degradation over time especially those used for the storage, transport and distribution of natural gas. The compatibility of these materials with natural gas including of hydrogen is dependent on the proportion of hydrogen added into the gas and is assessed with regard to several criteria:- permeation of hydrogen through metallic materials;- loss of integrity of these materials and adaptation of follow-up actions in service, surveillance and maintenance of equipment.This paper is devoted to the effect of hydrogen embrittlement (HE) caused by adding hydrogen into natural gas network on its design, maintenance, supervision and maximum allowable service pressure (MAOP) for smooth and damaged pipes.

Social cost-benefit assessment as a post-optimal analysis for hydrogen supply chain design and deployment: Application to Occitania (France)

A lot of recent studies have concluded that hydrogen could gradually become a much more significant component of the European energy mix for mobility and stationary fuel cell system applications. Yet, the challenge of developing a future commercial hydrogen economy still remains through the deployment of a viable hydrogen supply chain and an increasing fuel cell vehicle market share, which allows to narrow the existing cost difference regarding the conventional fossil fuel vehicle market. In this paper, the market penetration of hydrogen fuel cell vehicles, as substitutes for internal combustion engine vehicles has been evaluated from a social and a subsidy-policy perspective from 2020 to 2050. For this purpose, the best compromise hydrogen supply chain network configuration after the sequential application of an optimization strategy and a multi-criteria decision-making tool has been assessed through a Social Cost-Benefit Analysis (SCBA) to determine whether the hydrogen mobility deployment increases enough the social welfare. The scientific objective of this work is essentially based on the development of a methodological framework to quantify potential societal benefits of hydrogen fuel cell vehicles. The case study of the Occitania Region in France supports the analysis. The externality costs involve the abatement cost of CO2, noise and local pollution as well as platinum depletion. A subsidy policy scenario has also been implemented. For the case study considered, the results obtained that are not intended to be general, show that CO2 abatement dominates the externalities, platinum is the second largest externality, yet reducing the benefits obtained by the CO2 abatement. The positive externalities from air pollution and noise abatement almost reach to compensate for the negative costs caused by platinum depletion. The externalities have a positive effect from 2025. Using a societal cost accounting framework with externalities and subsidies, hydrogen transition timing is reduced by four years for the example considered.

A comparison of metaheuristics for the optimal capacity planning of an isolated, battery-less, hydrogen-based micro-grid

There has been growing interest in the development of sustainable energy systems using the potential of renewable energy sources. However, due to the intermittent nature of renewable energy sources, they must be accompanied by appropriate storage devices to be optimally integrated into so-calledsmartmicro-grid systems. The optimal design problem of sustainable micro-grids is associated with several nonlinearities and non-convexities, and therefore is not amenable to exact methods of optimization. Accordingly, this paper proposes a metaheuristic-based approach for optimizing the size and typology of the components of an off-grid hydrogen-based micro-grid, backed up with super-capacitors and stationary fuel cell systems, in the presence of a hydrogen refuelling station. The paper also compares the performance of six recent metaheuristics. The simulations are carried out for the climatic conditions of the Feilding area, New Zealand using MATLAB. Based on the comparative results, the moth-flame optimization algorithm is found to result in a significant reduction in the total net present cost of the system in comparison with other investigated algorithms. Notably, it outperforms the genetic algorithm and the particle swarm optimization in terms of solution quality by ~2.1% and ~3.2% (equating to cost savings of $123,910 and $188,129 from the target system). The results also demonstrate both the technical feasibility and cost-effectiveness of the proposed stand-alone micro-grid architecture. Particularly, the levelized costs of electricity and hydrogen of the conceptualized system are found to be $0.09/kWh and $4.61/kg, respectively, which are well below the current tariffs in New Zealand.

Thermal design of methane steam reformer with low-temperature non-reactive heat source for high efficiency engine-hybrid stationary fuel cell system

In hybrid fuel cell systems, the fuel-lean anode-off gas is very useful to improve the system efficiency via additional power generation or utilization of thermal energy for heating up of auxiliary devices. In this study, the thermal energy of the hybrid systems is firstly utilized in homogeneous charge combustion engine for additional power and is then supplied to heat up the external reformer. Different from other hybrid fuel cell systems, it is very difficult to utilize heat energy of exhausted gas from engine due to its low temperature characteristics. This study is concentrated on the computation analysis of external methane steam reformers with engine out exhausted gases. Computational model is validated with experiment and parametric study is conducted. Results show that the temperature uniformity of the longitudinal and radial directions is crucial for the methane conversion efficiency. Additionally, the methane conversion rate also depends on the performance of tube-side heat transfer. When the total methane flow is fixed, the methane conversion rate shows trade-off with increasing steam-to-carbon ratio (SCR). Finally, the sensitivity study shows that heat transfer area and reactor length are dominant parameters for steam reforming with engine out exhausted gases.

Effect of Sulfate Contaminant on ORR Activity and PEMFC Performanc

Lower cost materials for stack hardware and system components help reduce the overall cost of the automotive and stationary fuel cell systems and make these competitive in the market. However, low-cost system component materials need to provide similar function, performance and durability. Intelligently selecting low cost materials for application in polymer electrolyte membrane fuel cell (PEMFC) systems requires understanding the potential adverse effects that system contaminants may have on the fuel cell performance and durability. There are many prospective balance of plant (BOP) materials that can be used in fuel cell systems. Families of material, based on input from OEMs, fuel cell system manufacturers and other attributes like cost, physical properties, have been studied. These include structural materials, elastomers for seals and (sub)gaskets, and assembly aids (adhesives, lubricants). The contaminants from the BOP materials were leached out via an accelerated aging procedure. The leachates obtained from these plastics were a mixture of organics, inorganics, and ions. The sulfate anion was one of the anions identified in the leachates and was chosen as the model compound for further studies. Sulfate anions can also come from membrane degradation. Ex-situ electrochemical measurements were carried out to understand the impact of sulfate anion concentration on oxygen reduction reaction (ORR). The ORR scan rate and direction (low to high potential and vice versa) were studied to determine the effect of the initial state of the Pt surface on sulfate contamination. In-situ fuel cell experiments were also carried out. Sulfate anion was introduced to a working fuel cell to determine their effect on fuel cells performance. Our previous work showed that sulfate anion did not result in performance loss when it was infused into the cathode at 0.2 A/cm2. The cathode potential was greater than 0.8 V at this current density. It is postulated that sulfate contamination is potential dependent and that sulfate adsorption only occurs when Pt is in its metallic state. In the current study, the effect of potential on sulfate contamination will be studied by infusing sulfate into the cathode at several constant current densities. Several in-situ diagnostics such as infusion, cyclic voltammetry, electrochemical impedance spectroscopy, and I-V curves were carried out to better characterize the contaminant effects of sulfate anion. The goal is to better understand the contamination mechanisms of specific species so that mitigation strategies can be determined. The authors would like to acknowledge funding from the U.S. Department of Energy EERE Fuel Cell Technologies Office, under Contract No. AC36-08GO28308 with the National Renewable Energy Laboratory and collaborations with colleagues at GM. Structural plastic materials and leachates were provided by GM for this study.

Renewable hydrogen production by solar-powered methanol reforming

The present study demonstrates the possibility of generating hydrogen by methanol steam reforming at temperatures of 235–260 °C inside a non-concentrating solar collector, ideally for stationary fuel cell systems. In contrast to the current state-of-the-art, the solar collector provides all heat required for heating and evaporation of the reactants, endothermic reaction, and compensation of heat losses, without any external heat supply (such as from combustion of fuel or electric heating) and without the need for concentration of sunlight (as in conventional parabolic trough systems). Without the need for solar concentration, the system is simpler and more compact than conventional systems, and it can utilize all direct and indirect incident sunlight. The solar collector-reactor achieves hydrogen generation up to 6.62 LSTP min−1 per m2 collector area (equivalent to 1088 W m−2 LHV) under 1 sun, with solar-to-hydrogen efficiencies up to 78% and total energetic efficiencies (considering solar and fuel input) up to 43%.

(Invited) Understanding Cathodes for Solid Acid Fuel Cells By Coupling FIB-SEM 3D Reconstruction with Mathematical Modeling

Fuel cells based on the crystalline proton-conducting electrolyte CsH2PO4 (CDP) typically operate between 230 °C and 260 °C1. In this intermediate temperature regime, so-called solid acid fuel cell (SAFC) anodes are tolerant to high concentrations of impurities2, are amenable to internal reforming of multiple fuels3, and may possibly omit platinum entirely4. These properties make SAFCs excellent candidates for stationary fuel cell systems operating on fuels such as methanol or natural gas. A longstanding barrier to the adoption of SAFC technology has been the low activity and high precious metal content of the cathode. In the state-of-the-art cathode architecture, a macroporous framework of the CDP electrolyte is decorated with a percolating network of platinum nanoparticles that acts as both the oxygen reduction catalyst and the sole electronic conductor in the electrode. Typical SAFC cathode Pt loadings are greater than 1.75 mg/cm2, an amount circumscribed by the minimum quantity needed to obtain sufficient electrical conductivity in the electrode5. Despite the success of the current SAFC cathode design, only limited work has been done to date to understand the structure-property relationships governing its performance. Here we address this problem using an approach coupling ex situmicroscopic characterization and mathematical modeling with experimental input from electrochemical cell testing. Porous SAFC cathodes were sectioned using FIB/SEM to render a 3D reconstruction of a representative electrode sub-volume. A machine-learning algorithm was used to automatically segment image stacks to address segmentation problems due to gray level gradients and overlapping gray level peaks in the image histogram. Numerical analysis was performed to extract electrode physical properties (i.e. porosity, tortuosity). Electrode physical parameters from the 3D electrode reconstruction were used as inputs to a 1D macrohomogenous model similar to those applied previously to PEM fuel cells6. The model was used to self-consistently fit SAFC polarization curves, yielding, among other quantities, an electrochemically active area for the electrode, which has been notoriously difficult to measure in the SAFC system. We comment on these and other findings, as well as the utility of the model in addressing the SAFC system given some of the categorical distinctions between it and the PEM system. Acknowledgments This work is supported by ARPA-E via cooperative agreement DE-AR0000499. References 1 S.M. Haile, C.R.I. Chisholm, Kenji Sasaki, D.A. Boysen, and T. Uda, Faraday Discuss. 134, 17 (2007). 2 C. R. I. Chisholm, Dane A. Boysen, A. B. Papandrew, Strahinja K Zecevic, Sukyal Cha, Kenji A Sasaki, Áron Varga, Konstantinos P. Giapis, and S.M. Haile, Electrochem. Soc. Interface 18, 53–59 (2009). 3 T. Uda, D.A. Boysen, C. R. I. Chisholm, and S.M. Haile, Electrochem. Solid-State Lett. 9, A261 (2006). 4 Alexander B. Papandrew, Robert W. Atkinson III, Raymond R. Unocic, and Thomas a. Zawodzinski, J. Mater. Chem. A 3, 3984–3987 (2015). 5 Alexander B. Papandrew, Calum R.I. Chisholm, Ramez A Elgammal, Mustafa M. Özer, and Strahinja K Zecevic, Chem. Mater. 23, 1659–1667 (2011). 6 T.E. Springer, T.A. Zawodzinski, and S Gottesfeld, J. Electrochem. Soc. 138, 2334 (1991).

Effect of Caprolactam and Sulfate System-Derived Contaminants on Catalyst Activity and PEMFC Performanc

Lower cost materials for stack hardware and system components help reduce the overall cost of the automotive and stationary fuel cell systems and make these competitive in the market. However, low-cost system component materials need to provide similar function, performance and durability. Intelligently selecting low cost materials for application in polymer electrolyte membrane fuel cell (PEMFC) systems requires understanding the potential adverse effects that system contaminants may have on the fuel cell performance and durability. There are many prospective balance of plant (BOP) materials that can be used in fuel cell systems. Families of material, based on input from OEMs, fuel cell system manufacturers and other attributes like cost, physical properties, were chosen for this study include structural materials, elastomers for seals and (sub)gaskets, and assembly aids (adhesives, lubricants). Two types of low cost structural plastic materials – a polythlalamide and a polyamide – have been studied. The contaminants from the BOP structural material were leached out via an accelerated aging procedure. The leachates obtained from these plastics were a mixture of organics, inorganics, and ions. Organics that were identified in the leachate solutions via gas chromatography mass spectrometry (GCMS) include 1,8 Diazacyclotetradecane-2,7-dione (DCTDD), aniline, and caprolactam. These plastic materials also released anions: chloride, phosphate, nitrates, and sulfates. Of the organics, inorganics, and ions found in the leachate solution, caprolactam and sulfate were chosen for further study. These model compounds were introduced individually and as mixtures to a working fuel cell to determine their effect on fuel cells performance. Several in-situ diagnostics such as infusion, cyclic voltammetry, electrochemical impedance spectroscopy, and I-V curves were carried out to better characterize the contaminant effects of each model compound and mixtures of compounds. The preliminary in-situ results indicated that the organic compound caprolactam had a large negative effect on fuel cell performance and that the effect was not recoverable. On the other hand, infusion of sulfate into the fuel cell seemed to have no effect. The results also suggested that there is an interaction between caprolactam and sulfate. Ex-situ electrochemical measurements were also carried out to understand the impact of these individual and mixtures of compounds on the catalyst electrochemical surface area and the oxygen reduction reaction. The goal is to better understand the contamination mechanisms of specific species and their interaction with one another, leading to mitigation strategies. The authors would like to acknowledge funding from the U.S. Department of Energy EERE Fuel Cell Technologies Office, under Contract No. AC36-08GO28308 with the National Renewable Energy Laboratory and collaborations with colleagues at GM. Structural plastic materials and leachates were provided by GM for this study.

Multiple Advance Diagnostics to Probe the Effect of Balance of Plant Materials on Fuel Cell Performance

Extensive research on fuel cell stack materials has led to advances in lower cost, high performing materials. With the decrease in the cost of stack materials, lowering the cost of the balance of plant (BOP) components has increased in importance. In order to decrease the overall cost of the automotive and stationary fuel cell systems and make them as competitive as possible, low-cost system component materials that provide similar function, performance and durability are needed. However, intelligently selecting low cost materials for application in polymer electrolyte membrane fuel cell (PEMFC) systems requires understanding the potential adverse effects that system contaminants may have on the fuel cell performance and durability. Limited work in this area has been conducted to-date. There are many prospective BOP materials that can be used in fuel cell systems. Our material selection was based on the material’s physical properties (i.e., whether it will be stable in fuel cell operating conditions), commercial availability, cost and input from OEMs and fuel cell system manufacturer. Families of material chosen for the study include structural materials, elastomers for seals and (sub)gaskets, and assembly aids (adhesives, lubricants). Two types of low cost structural plastic materials – a polythlalamide and a polyamide – were studied. Leachates obtained from these plastics were a mixture of organics, inorganics, and ions and were introduced to a working fuel cell to determine their effect on the fuel cells performance. Organics that were identified in the leachate solutions via gas chromatography mass spectrometry (GCMS) include 1,8 Diazacyclotetradecane-2,7-dione (DCTDD), aniline, and caprolactam. These plastic materials also released anions: chloride, phosphate, nitrates, and sulfates. In-situmeasurements such as infusion, cyclic voltammetry, impedance spectroscopy, and I-V curves were carried out to better characterize the contaminants effects of the mixtures of compounds in the extracts. The effect of the individual organic model compound (caprolactam), anion (sulfate) and mixtures of the two species were also studied to better understand the contamination mechanisms of specific species and their interaction with one another. This presentation will also briefly describe the ex-situ electrochemical quartz crystal microbalance (EQCMB) technique used to study the adsorption effect of organic compounds, derived from system contaminants, on Pt surface. EQCMB was used to measure the change in mass of the electrode as a function of potential. The authors would like to acknowledge funding from the U.S. Department of Energy EERE Fuel Cell Technologies Office, under Contract No. AC36-08GO28308 with the National Renewable Energy Laboratory and collaborations with colleagues at GM and 3M. Structural plastic materials were provided by GM and membrane degradation products for this study were provided by 3M.

Determination of Charge and Mass Transfer for Molten Carbonate Fuel Cell Cathode Using NiO Coated Ring Electrode

Introduction Molten carbonate fuel cell (MCFC) systems have very high energy conversion for distributed generation systems, and the largest electric power generation capacity in stationary fuel cell systems. In order to improve energy conversion efficiency and durability, cathode and electrolyte materials are key factors. We found that the solubility of LaNiO3 in the La2O3 saturated molten alkaline metal carbonates is significantly smaller than that of NiO in the La2O3 free molten carbonates1), and should know the kinetics on the LaNiO3 in the carbonates for oxygen reduction reaction (ORR). However, even the kinetics of the ORR on the NiO is not clarified enough2). Furthermore, the performance of gas diffusion electrode for practical system should be affected by both charge and mass transfer.In this study, charge transfer on a sintered NiO electrode and mass transfer through a meniscus on the electrode have been investigated with chronoamperometry using a meniscus ring electrode to establish electrochemical method for the evaluation of charge and mass transfer separately. Experimental Li/Na (=52/48 mol %) or Li/K (=62/38 mol %) molten carbonate were used as an electrolyte. The working electrode was a sintered NiO on a gold ring electrode. The height of the working electrode from surface of molten carbonate was controlled by a micrometer. Reference electrode was a reversible oxygen electrode (ROE), and counter electrode was a gold coil electrode. The surface area of the sintered NiO was BET method.The oxygen reduction reaction current was determined with chronoamperometry (CA) from 10 to -10 mV vs. ROE. The initial current density was evaluated by extrapolation to t = 0 with the linear relation between current and the square root of time to determine mass transfer free polarization at 2mm of the height. The steady state current density was evaluated for 100 s after 500 s of CA at 4mm of the height with mass transfer resistance of the meniscus.Symmetry factor: a was determined with Allen-Hickling equation for the mass transfer free polarization curve, and the exchange current density: i 0 was determined with mass transfer free Butler-Volmer equation, the a and polarization curve. The limiting current density: i l was determined with Butler-Volmer equation with the i l, i 0, a, the steady state polarization curve. Results and discussion Figure 1 shows the i 0 (Fig. 1-a)) and the i lc (Fig. 1-b)) as a function of CO2 or O2 partial pressure in CO2-O2-Ar. The CO2 or O2 partial pressure was fixed at 0.1 atm for p O2 or p O2 function, respectively. The i 0 the i lc were determined at 2 mm height to minimize the influence of ohmic drop of the electrolyte and at 4 mm height to minimize mass transfer resistance of reaction gas through the meniscus. Here, the i 0 and the i lc are normalized the BET surface area and geometrical surface area, respectively. The BET surface area of the sintered NiO was 2.5 m2g-1. Therefore, the apparent exchange current density per geometrical surface area was 1000 times larger than the limiting current density. The dependence of the i 0s on the partial pressures were smaller than that of the i lcs. All slopes could not explained by a simple reaction mechanism model of peroxide, superoxide, or parcarbonate path2). The polarization of practical electrode depends on liquid – gas interface surface area rather than real surface area of the electrode3). Therefore, performance of the practical electrode is controlled by the combination of the charge and mass transfer, and the i 0 and the i lc, which is a function of gas solubility, diffusion coefficient, and morphology of molten carbonate film, should be an effective index to determine activity of electrode and property of electrolyte. References 1) K. Matsuzawa, Y. Akinaga, S. Mitsushima, and K. Ota, J. Power Sources, 196, 5007 (2011).2) T. Nishina, Y. Masuda and I. Uchida, Molten Salt Chem., 93, 424 (1993).S. Kuroe, M. Takeuchi, S. Nishimura, K. Ohtsuka, DENKIKAGAKU, 58, 928 (1990).

Manufacturing Readiness and Cost Impacts for PEM Stack and Balance of Plant

Balance-of-Plant (BOP) cost for PEM fuel cell systems are now equal to or exceeding the cost of PEM fuel cell stack. The fuel cell systems cost analyses funded by the Fuel Cell Technologies Office (FCTO) of the U.S. Department of Energy (DOE) confirms the near equivalency of the BOP cost to fuel cell stack cost for PEM fuel cells in the studies by Battelle[1], Lawrence Berkeley National Laboratory[2], and Strategic Analysis Inc.[3]. The cost equivalency between the BOP and the PEM fuel cell stack is observed over the full spectrum of fuel cell applications; Material Handling Equipment (MHE) fuel cell systems, stationary fuel cell systems, automotive fuel cell systems. James et al[4]evaluated PEM automotive fuel cell costs and found that at production rates of 30,000 automotive units per year or greater the BOP cost were more than the PEM fuel cell stack cost, as shown in Figure 1.Battelle[5] reports the BOP cost is 3.5X the cost of the fuel cell stack in their analysis of the cost of a PEM 10 kW fuel cells for MHE; these data are represented in Figure 2 where the balance of plant is 59% of the fuel cell system cost at production rates of 10,000 MHE fuel cell systems per year.For a PEM 100 kW hydrogen fueled stationary fuel cell systems, Wei and McKone[6]of Lawrence Berkeley National Laboratory (LBNL) reported the ratio of BOP-to-stack cost is 1.3 at production rates of 1,000 hydrogen fueled units per year. For a PEM 100 kW reformate fueled stationary power plants, the LBNL data demonstrate the ratio of BOP to fuel cell stack cost is 1.1 for a production rate of 10,000 fuel cell systems per year.LBNL evaluated smaller hydrogen fueled PEM stationary, backup power (BUP) systems and the ratio of BOP to fuel cell stack cost was 1.5 for a 10 kW system. At BUP system production levels of 50,000, the ratio of BOP-to-fuel cell stack cost increased to 2.3 in the LBNL data.A three part approach to improving BOP performance, durability and reduced cost is:Increasing awareness of BOP specifications for performance, durability and cost within the supply chain.Optimization of manufacturing processes to reduce cost of BOP componentsDevelopment of fuel cell system BOP components that meet original equipment manufacturers specifications. Increasing awareness of BOP specifications: For many years, the approach to fuel cell BOP components has been to use Off The Shelf (OTS) components developed for non-fuel cell applications. Overall, this approach has not been successful because of a lack of awareness of the OEM specifications by the BOP manufacturers. The Ohio Fuel Cell Coalition brought the OEMs and BOP manufacturers together to share specifications, discuss manufacturing capabilities, and establish acceptable cost targets. The results of these exchanges will be presented.Optimization of Manufacturing Processes for BOP Components: The FCTO has sponsored manufacturing R&D programs for the last three years. Manufacturing R&D for BOP components will be discussed and recommendations for optimization of manufacturing methods for specific BOP components presented.Development of Fuel Cell Balance-of-Plant Components: Replacement of OTS components that are mismatch for fuel cell applications will in many cases require alternative materials and specialized designs to meet the OEM durability and performance requirements. The R&D pathways to identify alternative materials and specialized designs will be discussed.

Stationary fuel cells – Insights into commercialisation

Stationary fuel cell systems have been under development for several decades and have been demonstrated for a number of years across Asia, Europe and North America. Commercialisation of these systems is now accelerating with small and large scale systems being installed worldwide. Successful commercialisation requires a dual approach to identifying both early adopters in specific market segments whilst also seeking to reduce costs on a year on year basis. This paper provides an oversight of the current status of commercialisation and explores the key cost and market segmentation challenges.

Operational characteristics of a planar steam reformer thermally coupled with a catalytic burner

High efficiency reforming is a key parameter of high temperature stationary fuel cell systems. In this study, a planar heat exchanger steam reformer (PHESR) was integrated with a catalytic combustor in order that the unused energy of the anode off-gas is delivered for heating and reforming. The PHESR was designed to use the anode off-gas of the externally reformed SOFC system because it has an efficiency problem. In the PHESR reactor, the heat is transferred from the catalytic burner to the reformer that has the smallest gradient of temperature difference between the two reactors.The thermal behaviors of the exothermic and endothermic reactions between the reactors were investigated experimentally. The parameters of the investigation were fuel utilization, inlet temperature, and air excess ratio. The comparison parameter was the volume fraction of hydrogen at the exit of the reforming side. The temperature gradients of two reactors were measured in the longitudinal direction. As expected, the temperature differences between the two reactors were crucial factors that required optimization. Furthermore, the geometric aspects between the finned and un-finned reactors were also investigated. The results demonstrate that the volume fraction of hydrogen at the exit is closely coupled with the geometric constraints and operating parameters.

The cost of domestic fuel cell micro-CHP systems

Numerous academic and industrial estimates place the cost of future mass-produced small stationary fuel cell systems at around $1000 per kW, which compares well with targets set by agencies such as the US Department of Energy. Actual sale prices do not fit so neatly with these targets, and are currently 25–50 times higher even though mass production began three years ago.This paper explores the void between academic projections and commercial reality. It presents a systematic review of cost data from manufacturers in Europe, Asia and the US, along with near-term projections from manufacturers and other relevant organisations. Using these data, the potential for cost reductions through industry scale-up and learning by doing are quantified. The minimum feasible price of a typical 1 kW natural gas combined heat and power system is then estimated from industry data.Based on the findings, even a heroic effort by industry is unlikely to reduce the price of small domestic-scale systems to the $1000/kW mark. By aligning the scope and boundaries of cost estimates with the realities of domestic microgeneration systems, we show that a long-term target of $3000–5000 for 1–2 kW systems is more realistic, and could feasibly be attained by 2020 at the current rate of progress.

Fuel quality issues with biogas energy – An economic analysis for a stationary fuel cell system

This paper reviews the information available on the impurities encountered in stationary fuel cell systems, their effects on the fuel cells, and the maximum allowable concentrations of select impurities suggested by manufacturers and researchers. A generic model of a molten carbonate fuel cell-based power plant operating on digester and landfill gas has been developed; it includes a gas processing unit, followed by a fuel cell system. The model includes the key impurity removal steps to enable predictions of impurity breakthrough, component sizing, and utility needs. These data, along with process efficiency results from the model, were subsequently used to calculate the cost of electricity. Sensitivity analyses were conducted to correlate the concentrations of key impurities in the fuel gas feedstock to the cost of electricity.

Efficient Hydrogen Production for a Stationary Fuel Cell System: Two-Degree-of-Freedom Control of a Steam Reformer Unit

This article focuses on an essential part of a stationary fuel cell-based power plant, namely the reforming unit that produces H2. The reformer is fueled by either CH4 or DME, depending on the catalyst. A detailed dynamic model of the reformer dynamics is derived, which takes into account the spatial distribution of system states such as temperatures and mass fractions. Parameters for the resulting model are identified and a modal transformation is applied to reduce computational complexity and enable comprehensible controller design. The inner loop of the cascaded controller aims at closely following a given H2 output trajectory. At the same time, the outer control loop keeps the CO output below a given maximum level, thus ensuring that only a minimum of climate relevant gases is exhausted.