Development Of Fuel Cells Research Articles

연료전지 자동차 내 수소 공급 시스템에서 드레인 밸브 특성에 따른 드레인 로직 최적화 및 연비와 운전안정성을 고려한 물 관리 전략 개발

연료전지 자동차 내 수소 공급 시스템에서 드레인 밸브 특성에 따른 드레인 로직 최적화 및 연비와 운전안정성을 고려한 물 관리 전략 개발

Development of Solid Oxide Fuel Cells at Versa Power Systems & 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 submegawatt applications. This paper highlights the status of VPS and FCE’s SOFC technology in the areas of cell, stack and system development.

Impact of Evolving Electrode Morphology on Fuel Cell Performance: From the Nano to Mesoscale

The performance of polymer electrolyte membrane fuel cells (PEMFCs) is primarily controlled by the materials within membrane electrode assemblies (MEAs), which consist of an anode and cathode separated by a proton-conducting membrane. Developing highly stable MEAs is one key to wide-spread commercialization of this clean energy technology. The electrodes consist of a complex hierarchal structure, which must be capable of simultaneously transporting hydrogen, protons, electrons, oxygen, and water to and way from the critical electrocatalytic active sites. In conventional PEMFCs, Pt serves as the active catalyst, and is sometimes alloyed with a transition metal such as Co or Ni to enhance activity or lower cost.[1] In non-platinum group metal (non-PGM) electrodes, the catalytically active site takes the form of Fe or Co metal-nitrogen-carbon (M-N-C) complexes.[2] In either case, understanding the evolution of these catalysts, and the complex support structures in which they reside, in relation to observed performance losses is essential for furthering fuel cell development. Scanning transmission electron microscopy (STEM) is an ideal analytical characterization tool for performing both pre- and post-mortem nano to mesoscale compositional and structural characterization of the individual material components in MEAs. STEM has been used to quantify key changes responsible for performance gains and losses during fuel cell conditioning and cycling.[3,4] These structural changes can vary widely in both extent and scale, from carbon-corrosion-related electrode thinning at the micron scale to dealloying-induced reordering on the surfaces of advanced Pt-alloy catalysts at the atomic scale. This presentation will focus on three topics spanning multiple length scales in the MEA. Beginning at the atomic scale, strain effects and skeleton structures arising from in situ Ni dealloying in Pt-alloy nanostructured thin films (NSTF) will be presented. The surface structure and composition is critical to electrocatalytic activity, and, as shown by the aberration-corrected Z-contrast STEM image in Fig. 1a, these structures can be resolved with atomic resolution. Changes in surface structure/strain will be studied as a function of fuel cell cycling and electrochemical activity. At the nanoscale, carbon support effects on Pt anchoring and agglomeration will be presented, highlighting the critical role that catalyst-support interactions and corrosion-resistant supports play in MEA durability (Fig. 1b). Finally, at the mesoscale, changes in electrode structure with aging in non-PGM MEAs will be presented, highlighting the key role that hierarchal pore structures (spanning the micro to macro) play in fuel cell performance. Complementary imaging and compositional mapping by energy dispersive X-ray spectroscopy, as shown in Fig. 1c, provide unique insight into how both changes in mechanical and chemical structure impact durability. References V. R. Stamenkovic et al., Nat. Mater. 6 (2007) 241.G. Wu, K. L. More, C. M. Johnston, P. Zeleany, Science 332 (2011) 443.D. A. Cullen et al., J. Mater. Chem. A, 3 (2015) 1660. B. Han et al., Energy Environ. Sci., 8, 258 (2015). Acknowledgements Research sponsored by the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy (DOE) and ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility. Figure 1

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

Fuel Cell Energy, inc (FCE) and its wholly-owned subsidiary Versa Power Systems (VPS) are advancing the current state of Solid Oxide Fuel Cell (SOFC) technology towards commercial deployment for efficient and nonpolluting generation of electric power from natural gas and other fuels such as coal. SOFC technology represents an important opportunity to utilize fossil fuels in an efficient and environmentally-friendly manner. SOFCs are scalable, efficient (not subject to Carnot cycle limitations), and produce low emissions (e.g. nitrogen oxides) compared to combustion-based electrical power generation technologies (due to lower operating temperatures). SOFC power systems have the potential to achieve greater than 60 percent efficiency (based on higher heating value of fuel) and more than 97 percent carbon capture at a cost-of-electricity that is projected to be approximately 40 percent below that presently available through integrated gasification fuel cell (IGFC) systems with carbon capture. An attractive pathway to deployment of either IGFC or natural gas-fueled fuel cell (NGFC) systems is through near-term market opportunities in natural gas fueled distributed generation (DG) applications. The recent advancements in the base technology include: Reduced anode thickness from 1 mm to 0.6 mmDemonstration of steady-state cell operation at 500 mA/cm2 for over 2 years with less than 0.35% per 1000 hour degradation rateDemonstration of stable cell operation in high cathode gas humidity environment

Time Resolved DXAS Study on Micro and Nano NiO/Ce0.9Gd0.1O1.95 Cermets for Intermediate Temperature Solid Oxide Fuel Cells

The development of Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFC) as high efficient energy conversion systems requires the optimization of its components: cathode, anode and electrolyte. CeO2-based materials present excellent catalytic properties for the oxidation of H2 and CH4 fuels. Through the incorporation of metals oxides (Gd2O3, Sm2O3, Y2O3) in the CeO2 lattice the ionic conductivity can be significantly improved, becoming good electrolytes, particularly (Ce,Gd)O2- d (CGO) compound. Furthermore, the addition of metals such as Ni or Cu enhances the material electronic conductivity, thus enabling them as efficient IT-SOFC anodes [1]. It is recognized that the polarization characteristics of Ni-CGO cermet anodes are strongly affected by their preparation conditions, which determine the microstructure and morphology of these materials. For that reason, further exploration of new microstructures has to be done in order to improve anode performance [2]. In a previous work we presented a new modified sol-gel method to incorporate Ni into the precursors solution, which produced a powder with a very homogeneous Ni distribution resulted in smaller particle sizes with narrower distribution than the commercial cermet [3]. In this work, we present a study of the performance of these anodes sintered at different temperatures for the hydrogen oxidation reaction. The electrode polarization resistance is evaluated through Electrochemical Impedance Spectroscopy (EIS) on symmetric cells, while the cell power of Ni-CGO/CGO/LSCF configuration is measured in a home-made equipment. The structural and morphological characterization are analyzed by X-Ray Diffraction and Transmission and Scanning Electron Microscopy, respectively. The study of the oxidation state and coordination of Ce and Ni in these cermets, simulating in-operando conditions, was performed using synchrotron Dispersive X-ray absorption spectroscopy (DXAS) technique. The correlation between the electrochemical behavior, electronic properties and microstructural characteristics will be discussed. [1] W.C. Chueh, Y. Hao, W. Jung and S.M. Haile, Nature Materials 11 (2012) 155-161. [2] Z. Liu, B. Liu, D. Ding, M.F. Liu, F.L. Chen, C. R. Xia, Journal of Power Sources 237 (2013) 243-259. [3] A. Fernandez Zuvich, A. Soldati, S. Larrondo, M. Saleta, D.G. Lamas, L. B. Baqué, A. Caneiro and A. Serquis, ECS Transactions 64 (2014) 233-240.

(Invited) Microbial Fuel Cell Development for Practical Applications Robotics, Urinals and Novel Transistor Analogy

Microbial fuel cells (MFCs) convert organic waste directly into electricity, which is a competitive advantage over other energy generating systems. It is a technology that offers an environmentally friendly service at high-energy conversion efficiency. Full commercialization has yet to be achieved in areas such as wastewater treatment and remote power applications, due to challenges with the level of power output from individual units, cost of materials and scale-up. Unlike some conventional chemical fuel cells that are now fully commercial, MFCs are still at pilot scale testing [1-4]. However, several smaller-scale MFC-based applications have been implemented including, biochemical oxygen demand (BOD) measuring sensors (HABS2000, KORBI), benthic MFCs as on-site power sources for conventional sensors [5-7] and power sources for small electronic gadgets, mobile phones and robots, as well as Pee Power urinals [3, 8, 9]. Single MFCs can generate on average <0.5V at maximum power transfer, which is lower than what electronic circuits and peripheral devices require. Scaling up is therefore critical for the technology to be implemented in practice and find a route to market, and for this purpose several approaches have been proposed. One approach is to enlarge individual units to scale [2], and the second is to miniaturise individual units [10] and stack collectives of these small units together [11, 12]. Independent of size or volume, more than one unit will need to be connected together to increase the voltage and current up to operational levels. This can be in series (voltage boost), parallel (current boost) or a combination of series and parallel (voltage + current boost). As an alternative to these common connections, a novel method of MFC configuration is suggested in this work, with the introduction of added electrodes – so-called “pins”. The purpose of this type of connection is to enable control and monitoring of the MFC by modulating the physicochemical environment and the idea is derived from electronic transistors and control theory. This long-term study has been focusing on the development of MFCs for practical applications and scale-up. Through this approach, a novel transistor analogy is proposed with potential for improving power, controlling biochemical reactions, sensing and unconventional computation. Acknowledgements This work has been supported by the UK EPSRC, grant numbers EP/I004653/1 and EP/L002132/1 and Bill & Melinda Gates Foundation, grant no. OPP1094890.

Modeling and Simulation of 1.2 kW Nexa PEM Fuel Cell System

This work concerns the fuel cell systems modeling for their diagnosis. Particularly, we are interested in the systems based on the Nexa 1200W PEM fuel cell. To do this, a dynamic model of this fuel cell taking account of the different physical and chemical phenomena within the stack is presented. It is based principally based on Nerst equation and the use of certain parameters of the Nexa fuel cell provided by the manufacturer. Furthermore, it is accomplished bya certain number of original experimental tests (load modulation method). This model which is designed fortransportation applications contributes to the development offuel cells advanced models because it ensures the decoupling between the different internalphysical phenomena.In fact, to simplify the vehicle motor control, the established model is controlled by an average current at its input. It is especially shown that the membrane of the fuel cell model is solicited by the harmonicsgenerated by the static converters used in the vehicle powertrain powered by the 1.2 kW Nexa fuel cell model. The very important result achieved is that we cantolerate the current harmonics because the double layer capacitor realizes efficient high frequencies harmonic filtering. In this case, the systemstability is noticed. However, the results obtained confirm the use of the Nexa fuel cell system not only in powertrain, but in power electronics generally.

AFC reaches milestone 200 kW output from German KORE system

UK-based AFC Energy reports that, following an intense and accelerated 12-month fuel cell development programme, it has successfully delivered gross electrical output in excess of 200 kW at its KORE alkaline fuel cell power plant in Stade, Germany.

排気ガスからの電力回収を目的とした固体酸化物形燃料電池の開発

排気ガスからの電力回収を目的とした固体酸化物形燃料電池の開発

Economic analysis of fuel cell installations at commercial buildings including regional pricing and complementary technologies

This paper presents results from sensitivity studies conducted using the Distributed Generation Build-out Economic Assessment Tool (DG-BEAT). The viability of meeting commercial building loads with a stationary fuel cells is studied under different conditions of electricity pricing, dispatch strategies, and complementary technologies. Key findings support the notion that fuel cells are becoming economically viable alternatives in California, New York and Connecticut at installed costs of $7000–10,000/kW. Michigan is identified as another state well suited to fuel cell development with heat recovery. Fuel cell installations reduce net carbon emissions for commercial buildings by 20–30% when compared to local, time-resolved, grid emissions. Grid sell-back, at 50% retail price, significantly improves the economics of a base load fuel cell, but has little impact for a dispatchable system. At installed costs below $5000/kW, load following capability results in significant additional cost reductions as the generating capacity is increased beyond the building's base load requirements. Complementary technologies such as chillers and thermal storage have a pronounced impact, particularly in warmer climates. Installing fuel cells paired with electric chillers and thermal storage in Florida at buildings with exceptionally high air conditioning demands can achieve the same economic benefit as a typical New York building.

Intelligent Energy to develop embedded fuel cells for smartphones

UK-based Intelligent Energy has signed an agreement with an ‘emerging’ – but unnamed – smartphone OEM to create a tailored PEM fuel cell development and integration programme for a specific smartphone application. For some time IE has been engaging with several potential partners across the consumer electronics spectrum in relation to its embedded fuel cell technology.

Unravelling the Proton Conduction Mechanism from Room Temperature to 553 K in a 3D Inorganic Coordination Framework.

The preparation of proton-conducting materials that are functional and stable at intermediate temperatures (393-573 K) is a focal point of fuel cell development. The purely inorganic material, HNd(IO3)4, which possesses a dense 3D framework structure, can reach a maximum of 4.6 × 10(-4) S·cm(-1) at 353 K and 95% relative humidity and exhibit a high conductivity of 8.0 × 10(-5) S·cm(-1) from 373 to 553 K under the flow of wet N2. HNd(IO3)4 exhibits a variety of improvements including high thermal stability, low solubility in water, and resistance to reducing atmosphere. The proton conductivity in such a wide temperature range originates from the intrinsic liberated protons in the structure and the resulting 1D hydrogen-bonding network confirmed by bond valence sum calculation and solid-state NMR analysis. Moreover, two different activation energies are observed in different temperature regions (0.23 eV below 373 K and 0.026 eV from 373 to 553 K), indicating that two types of proton motion are responsible for proton diffusion, as further domenstrated by temperature-dependent open-circuit voltage hysteresis in a tested fuel cell assembly as well as variable-temperature and double quantum filtered solid-state NMR measurements.

Cover Picture: The Role of Microfabrication and Nanotechnology in the Development of Microbial Fuel Cells (Energy Technol. 10/2015)

Cover Picture: The Role of Microfabrication and Nanotechnology in the Development of Microbial Fuel Cells (Energy Technol. 10/2015)

The Role of Microfabrication and Nanotechnology in the Development of Microbial Fuel Cells

AbstractInnovative solutions are paramount to the identification and development of alternative energy resources, specifically for the production of potable water. Microbial fuel cells (MFCs) are a trending emerging technology that promises green energy production while simultaneously treating wastewater. At present, several research efforts are working towards determining which bacteria, fuels, and materials are optimal for developing the most efficient MFCs; microsized MFCs have a key role in this goal. Therefore, in this Review, we summarize recent microfabrication techniques for building microsized cells and elaborate on their advantages and the challenges that need to be overcome. We will then focus on the integration of nanomaterials into MFCs and finish with an overview on the challenges to scale up MFCs and potential uses for these miniature cells.

Development of Ceria-Based Microtubular Solid Oxide Fuel Cells

It is well known that gadolinia-doped ceria (GDC) has high oxide-ion conductivity for electrolyte, and it improves electrochemical activities for fuel oxidation and oxygen reduction for electrodes of solid oxide fuel cell (SOFC). In this work, we investigated the usage of ceria for cathode, anode and electrolyte of microtubular SOFCs for low temperature operation and direct hydrocarbon utilization.

Development of Alkaline Fuel Cells Using Hydroxide-Ion Conductive Layered Double Hydroxides

Layered double hydroxides (LDHs) intercalated with CO3 2- show high hydroxide ion conductivity of the order of 10-3 S cm-1 under 80% relative humidity. In the present study, (Ni, Mn)-Al LDHs and (Ni, Mn)-Fe LDHs intercalated with CO3 2- were prepared. The conductivity of (Ni, Mn)-Al LDH and (Ni, Mn)-Fe LDH was higher than that of Ni-Al LDH or Ni-Fe LDH. These LDHs were applied to the catalyst layer in an alkaline fuel cell for the improvement of the oxygen reduction reaction (ORR) at the triple phase boundary (TPB) in the catalyst layer. The addition of LDHs to the catalyst layer increased the current for ORR, indicating that hydroxide ion conducting LDHs introduced OH- conducting paths and increased TPB region within the catalyst layer. Above all, the addition of (Ni, Mn)-Fe LDH to the catalyst layer more effectively increased the reduction current for ORR than the addition of (Ni, Mn)-Al LDHs or Ni-Fe LDH. H2-O2 fuel cells with Ni-Al or Mg-Al LDHs as an electrolyte and MnO2 as the cathode catalyst were fabricated. The H2-O2 fuel cells were confirmed to be operated.

Effects of Cobalt Cation on Low Pt-loaded PEM Fuel Cell Performance

Pt alloys such as PtCo are attractive as cathode catalysts in PEM fuel cell systems due to their high catalytic activities. However, in a fuel cell the non-noble metal such as cobalt can dissolve and not only cause degradation of oxygen reduction activity but can also migrate into the ionomer inducing proton conduction loss, especially at high current densities. These losses are not readily explained quantitatively using our current fuel cell model. In this study, we conducted controlled experiments where known amounts of Co cation were exchanged into membrane-electrode assemblies (MEAs). The effects of Co level on oxygen reduction activity, electrode and membrane proton conductions, and electrode oxygen transport were studied using multiple electrochemical methods on MEAs. These newly acquired results will be used to improve our current model and provide direction for future fuel cell development.

Onsite Deposition of Self-Repairing Biomimetic Nanostructured Ni Catalysts with Improved Electrocatalysis toward Glycerol Oxidation for H2 Production

In this study, a technology was developed for producing hydrogen via glycerol electrolysis. A homogeneous stock solution of a Ni catalyst was prepared, conserved and used for an alkali electrolyte with no precipitation due to the coordinative and protective effects of sodium tartrate and polyvinyl pyrrolidone (PVP). The deposition of the Ni(OH)2 catalyst and its electrocatalysis toward glycerol occurred nearly simultaneously. Tedious and laborious procedures for preparing common catalysts and immobilizing them on an electrode surface were not required. The Ni(OH)2 catalyst film self-repaired due to the presence of Ni in the alkali electrolyte. This technique also exhibited satisfactory electrocatalytic performance for hydrogen production via glycerol electrolysis with a high transformation efficiency and good stability. The Ni(OH)2 electrocatalyst electrolyzed glycerol at the glassy carbon anode to produce H2O and CO2, and this H2O was electrochemically reduced at the Pt cathodic electrode to release H2. The formation of bubbles and the presence of PVP provided the anodic electrode surface a brilliant iridescence similar to that of butterfly wings due to the distributed Ni(OH)2 nanostructures with large circular spaces and small nanoholes. Such systems using an abundance of the non-noble metal Ni have potential applications for solar energy and fuel cell development.

Advanced Impedance Spectroscopy Study of the Influence of the Crystalline Structure on the Ionic Conduction of Thin Solid-State Electrolytes

Solid electrolytes exhibit electrical conductivity due to the presence of mobile ions which act as charge carriers through the crystalline structure. For their use in solid oxide fuel cells (SOFCs), a sufficient electrical conductivity is achieved by operating at high temperatures. To reduce the application temperature, research is dedicated to increase the electrical conductivity of the ceramic material otherwise. One way is decreasing the film thickness. Yet, the relationship between the material crystallinity and the ion conductivity may be reinterpreted when reducing the thickness to the micrometer and nanometer scales. Another way is by reducing the grain size. At present it is not clear how the microstructure of solid state electrolytes affect the electrical conduction. In literature, the experiments on nanocrystalline solid oxides yield contradictory observations [1-6]. A good understanding of the relationship between microstructure and ion conductivity would open the possibility to engineer advanced thin materials for solid oxide fuel cells. We propose an experimental and modeling approach that aims at unraveling the electrical behavior of thin film solid state electrolytes, by considering the crystalline nature of the material. Through careful comparison of simulations and measurements we want to explain the observed electrical properties of these materials to predict how their conductivity can be enhanced. In this research, the complex electrical properties at different temperatures of yttrium-doped ceria electrolytes, with different thicknesses and grain sizes, are determined by electrochemical impedance spectroscopy (EIS). The solid oxide is deposited by reactive magnetron sputtering, which allows us to modify the morphology and composition of the thin film in a controlled and flexible way [7]. In the EIS characterization, improved electrode geometry is also searched. Experiments with platinum co-planar electrodes are performed and compared with those with an interdigital electrode structure. The specific electrode geometry is designed by 2D simulations for a solid oxide film in contact with the substrate. A finite element model of the electrical conductivity was recently developed to simulate impedance spectra and electrical conductivities as a function of grain size and temperature [8]. More rigorous than the dilute solution models, it is based on the application of the linear phenomenological relations to a crystal lattice. The impedance modeling provides a description of the electrical behavior of the material. The EIS results are then compared with the ones generated by the finite element model. The combined analysis aims to elucidate the experimental evidence that is not explained by the available physical models. Therefore, it represents a strong approach to understand the electrical properties and ion conduction of solid electrolytes. [1] J. Maier “Ionic conduction in space charge regions”, Progress in Solid State Chemistry 23 (1995) 171–263. [2] J. Maier “Nano-sized mixed conductors (Aspects of nano-ionics. Part III)”, Solid State Ionics 148 (2002) 367–374. [3] X. Guo, R. Waser “Electrical properties of the grain boundaries of oxygen ion conductors: Acceptor-doped zirconia and ceria”, Progress in Materials Science 51 (2006) 151–210. [4] J. Maier “Nanoionics: ionic charge carriers in small systems”, Physical Chemistry Chemical Physics 11 (2009) 3011–3022. [5] C. Peters, A. Weber, B. Butz, D. Gerthsen, E. Ivers-Tiffée “Grain-Size Effects in YSZ Thin-Film Electrolytes”, Journal of the American Ceramic Society 92 (9) (2009) 2017–2024. [6] X. Guo “Can we achieve significantly higher ionic conductivity in nanostructured zirconia?”, Scripta Materialia 65 (2011) 96–101. [7] S. Mahieu, P. Ghekiere, G. De Winter, S. Heirwegh, D. Depla, R. De Gryse., O.I. Lebedev, G. Van Tendeloo “Mechanism of preferential orientation in sputter deposited titanium nitride and yttria-stabilized zirconia layers”, Journal Of Crystal Growth 279 (1-2) (2005) 100-109. [8] D. Van Laethem, A. Hubin, J. Deconinck “Finite element modelling of the electrical conductivity of acceptor doped ceria”, 6th International Conference on Fundamentals and Development of Fuel Cells, 3rd- 5th February, Toulouse (France).

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.