Cover Fuel Cells 1/2020

Rod Borup is a Team Leader in the fuel cell program at Los Alamos National Lab in Los Alamos, New Mexico. He received his B.S.E. in Chemical Engineering from the University of Iowa in 1988 and his Ph.D. from the University of Washington in 1993. He has worked on fuel cell technology since 1994, working in the areas of hydrogen production and PEM fuel cell stack components. He has been awarded 12 U.S. patents, authored over 40 papers related to fuel cell technology, and presented over 50 oral papers at national meetings. His current main research area is related to water transport in PEM fuel cells and PEM fuel cell durability. Recently, he was awarded the 2005 DOE Hydrogen Program R&D Award for the most significant R&D contribution of the year for his team's work in fuel cell durability and was the Principal Investigator for the 2004 Fuel Cell Seminar (San Antonio, TX, USA) Best Poster Award. Jeremy Meyers is an Assistant Professor of materials science and engineering and mechanical engineering at the University of Texas at Austin, where his research focuses on the development of electrochemical energy systems and materials. Prior to joining the faculty at Texas, Jeremy workedmore » as manager of the advanced transportation technology group at UTC Power, where he was responsible for developing new system designs and components for automotive PEM fuel cell power plants. While at UTC Power, Jeremy led several customer development projects and a DOE-sponsored investigation into novel catalysts and membranes for PEM fuel cells. Jeremy has coauthored several papers on key mechanisms of fuel cell degradation and is a co-inventor of several patents. In 2006, Jeremy and several colleagues received the George Mead Medal, UTC's highest award for engineering achievement, and he served as the co-chair of the Gordon Research Conference on fuel cells. Jeremy received his Ph.D. in Chemical Engineering from the University of California at Berkeley and holds a Bachelor's Degree in Chemical Engineering from Stanford University. Bryan Pivovar received his B.S. in Chemical Engineering from the University of Wisconsin in 1994. He completed his Ph.D. in Chemical Engineering at the University of Minnesota in 2000 under the direction of Profs. Ed Cussler and Bill Smyrl, studying transport properties in fuel cell electrolytes. He continued working in the area of polymer electrolyte fuel cells at Los Alamos National Laboratory as a post-doc (2000-2001), as a technical staff member (2001-2005), and in his current position as a team leader (2005-present). In this time, Bryan's research has expanded to include further aspects of fuel cell operation, including electrodes, subfreezing effects, alternative polymers, hydroxide conductors, fuel cell interfaces, impurities, water transport, and high-temperature membranes. Bryan has served at various levels in national and international conferences and workshops, including organizing a DOE sponsored workshop on freezing effects in fuel cells and an ARO sponsored workshop on alkaline membrane fuel cells, and he was co-chair of the 2007 Gordon Research Conference on Fuel Cells. Minoru Inaba is a Professor at the Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Japan. He received his B.Sc. from the Faculty of Engineering, Kyoto University, in 1984 and his M.Sc. in 1986 and his Dr. Eng. in 1995 from the Graduate School of Engineering, Kyoto University. He has worked on electrochemical energy conversion systems including fuel cells and lithium-ion batteries at Kyoto University (1992-2002) and at Doshisha University (2002-present). His primary research interest is the durability of polymer electrolyte fuel cells (PEFCs), in particular, membrane degradation, and he has been involved in NEDO R&D research projects on PEFC durability since 2001. He has authored over 140 technical papers and 30 review articles. Kenichiro Ota is a Professor of the Chemical Energy Laboratory at the Graduate School of Engineering, Yokohama National University, Japan. He received his B.S.E. in Applied Chemistry from the University of Tokyo in 1968 and his Ph.D. from the University of Tokyo in 1973. He has worked on hydrogen energy and fuel cells since 1974, working on materials science for fuel cells and water electrolysis. He has published more than 150 original papers, 70 review papers, and 50 scientific books. He is now the president of the Hydrogen Energy Systems Society of Japan, the chairman of the Fuel Cell Research Group of the Electrochemical Society of Japan, and the chairman of the National Committee for the Standardization of the Stationary Fuel Cells. ABSTRACT TRUNCATED« less

Today, the development of active and stable catalysts still represents a challenge to be overcome in the research field of low-temperature fuel cells.[...]

Polymers for Electrolyte Membrane Fuel Cells

Fuel Cells. Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly into electrical and thermal energy. In a typical fuel cell, gaseous fuels are fed continuously to the anode (negative electrode) compartment, and an oxidant, eg, oxygen or air, is fed continuously to the cathode (positive electrode) compartment. The electrochemical reactions take place at the electrodes to produce an electric (direct) current. The fuel cell theoretically has the capability of producing electrical energy for as long as the fuel and oxidant are fed to the electrodes. In reality, degradation or malfunction of components limits the practical operating life of fuel cells. Besides the direct production of electricity, heat is also produced in fuel cells. This heat can be effectively utilized for the generation of additional electricity or for other purposes, depending on the temperature. A practical consideration for fuel cells is compatibility with the available fuels and oxidants. One of the main attractive features of fuel cell systems is the expected high fuel‐to‐electricity efficiency. This efficiency, which runs from 40–60% based on the lower heating value (LHV) of the fuel, is higher than that of almost all other energy conversion systems. The two primary impediments to the widespread use of fuel cells are high initial cost and short operational lifetime. A variety of fuel cells has been developed for terrestrial and space applications. Fuel cells are usually classified according to the type of electrolyte used in the cells as polymer electrolyte fuel cell (PEFC), alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), and solid oxide fuel cell (SOFC). Fuel cells operating on pure H 2 and O 2 provide a useful power source in remote areas such as in space or under the sea where system weight and volume are important parameters. On the other hand, fuel cell power plants operating on fossil fuels and air offer the potential for environmentally acceptable, highly efficient, and low cost power generation. The minimum technical requirements for fuel cells for four different types of applications, ie, for buildings, industry, transportation, and utilities are given. From the standpoint of commercialization of fuel cell technologies, there are two challenges: initial cost and reliable life. Several activities, would strongly boost the prospects for fuel cell technology and include the development of (1) an active electrocatalyst for the direct electrochemical oxidation of methanol; (2) improved electrocatalysts for oxygen reduction; and (3) a more CO‐tolerant electrocatalyst for hydrogen.

Challenges and opportunities in modelling of proton exchange membrane fuel cells (PEMFC)

The promising development of hydrogen and fuel cell technologies has garnered increased attention in recent years, assuming a significant role in industrial applications and the decarbonisation of the shipping industry. Given that the shipping industry generates considerable greenhouse gas emissions, it is crucial and imperative to implement integrated solutions based on clean energy sources, thereby meeting the proposed climate objectives. This study presents the standard hydrogen production, storage, and transport methods and analysis technologies that use hydrogen fuel cells in marine and industrial applications. Technologies based on hydrogen fuel cells and hybrid systems will have an increased perspective of application in industry and maritime transport under the conditions of optimising technological models, developing the hydrogen industrial chain, and updating standards and regulations in the field. However, there are still many shortcomings. The paper’s main contribution is analysing the hydrogen industrial chain, presenting the progress and obstacles associated with the technologies used in industrial and marine applications based on hydrogen energy.

This paper describes the designing and evaluation of an alternative energy system which consists of PEMFC, PV, PEM electrolyser, methane reformer and hydrogen tank. In order to find out the minimum capacity of the components, a system sizing model is developed in MATLAB based on meteorological and electrical demand data. Three scenarios are considered based on different combinations of solar energy and fossil fuel energy as energy resources. The heating energy produced by the fuel cell is recovered for supplying domestic hot water while the system would supply electrical energy. Results show that system sizing strongly depends on scenarios and unit cost of electricity decreases through the reduction of solar energy contribution in scenarios. CHP analysis indicates that the overall energy efficiency and fuel cell efficiency are increased approximately 3.4% and 40% respectively. Furthermore, the cost benefit ratio of using the fuel cell heat is equivalent to 25% of the total annual cost of the electricity.

If the necessary infrastructure can be provided, a practical future electric vehicle will be an efficient hydrogen-powered hybrid operating on a polymer fuel cell. Light weight, lowest cost and high efficiency imply an atmospheric pressure, rather than a pressurized, system. Polymer fuel cells require humidification for ionic conductivity, which means that product water is normally rejected as liquid. Atmospheric pressure systems of this type are difficult to operate. A self-humidified atmospheric pressure system operating at higher temperature (about 75-80 °C) on oxygen-enriched air rejecting product water in the vapour phase is described. It combines the advantages of unpressurized operation with the higher power density of a pressurized system, but with much lower parasitic power requirements.

Fuel cell is the technology that, nowadays, is deemed having a great potential to be used in supplying energy. Basically, fuel cells can be categorized particularly by the kind of employed electrolyte. Several fuel cells types which are currently identified having huge potential to be utilized, namely, Solid Oxide Fuel Cells (SOFC), Molten Carbonate Fuel Cells (MCFC), Alkaline Fuel Cells (AFC), Phosphoric Acid Fuel Cells (PAFC), Polymer Electron Membrane Fuel Cell (PEMFC), Direct Methanol Fuel Cells (DMFC) and Regenerative Fuel Cells (RFC). In general, each of these fuel cells types has their own characteristics and specifications which assign the capability and suitability of them to be utilized for any particular applications. Stationary power generations and transport applications are the two most significant applications currently aimed for the fuel cell market. It is generally accepted that there are lots of advantages if fuel cells can be excessively commercialized primarily in context of environmental concerns and energy security. Nevertheless, this is a demanding task to be accomplished, as there is some gap in fuel cells technology itself which needs a major enhancement. It can be concluded, from the previous study, cost, durability and performance are identified as the main limitations to be firstly overcome in enabling fuel cells technology become viable for the market.

Fuel cells (FC) are power sources that convert electrochemical energy into electrical energy in a clean and efficient manner. FC technology presents one of the most promising solutions to reduce fossil fuel consumption. FC simulators are expected to play a key role in the development of FC systems due to their low cost and flexibility. This paper presents the development of a stand-alone FC simulator based on a low cost digital signal processor (DSP). The proposed fuel cell simulator emulates the electrical dynamic behavior of a direct methanol fuel cell (DMFC) stack. This is achieved via a power converter with a robust control strategy with fast dynamic response. The reference signal for the power converter that represents the dynamic behavior of the FC is generated from an experimental model of the DMFC that can be extended to other FCs. The output of the FC simulator is a reproduction of the dynamic behavior of DMFC model, thus emulating a FC stack. Test results of the FC simulator and the actual FC are compared and discussed. From the viewpoint of educational purposes, the proposed FC simulator provides a flexible solution at a low cost for student and engineers in training. In addition, the proposed simulator can be used for the design and development of FC power electronics

Hydrogen fuelled Proton Exchange Membrane Fuel Cells (PEMFCs) are being developed as next generation energy delivery devices to replace conventional combustion technology and enable the development of a hydrogen economy. The attraction of the technology is its ability to operate at higher efficiencies than traditional combustion technology, reducing overall harmful gas and particulate emissions. When hydrogen derived from renewable resources is used as the energy vector, an environmentally benign system is created. Despite the promise held by PEMFC technology, important materials design and system engineering challenges still exist, preventing commercialisation. From a materials perspective, proton exchange membranes capable of operating at or above 140oC need to be developed. This minimum operating temperature is necessary for specific applications in transportation, to reduce catalyst poisoning by carbon monoxide and to increase the system’s ability to dissipate heat. System engineering challenges are due to poor understanding of the water balance in the fuel cell, the lack of design metrics for fuel cell systems and a poor understanding of dynamic operation. This thesis explores each of the aforementioned challenges as follows: • A review of the latest developments in solid acid membranes for PEMFCs operating at 140oC is presented. The most promising areas for future advancements are identified, analysed and discussed and the concept of a thin film, inorganic membrane fuel cell is introduced. • Sol-gel synthesised zirconium phosphate membranes are investigated as an alternative to layered zirconium phosphate proton conductors. The materials show conductivity values similar to α-zirconium phosphate. The advantage of the solgel synthesis route is that the materials can be manufactured as thin film proton conducting membranes. • Sol-gel titanium phosphate membranes are synthesised and their proton conduction mechanism and chemical stability are investigated. The materials show stable conductivity values up to 0.0044 S.cm−1 at 100oC and 100% relative humidity. 31P MAS NMR was used to elucidate the functional groups and develop a model for the Grotthuss proton conduction mechanism. • The STR fuel cell, which can fully self humidify when operating with dry feeds, is characterised and demonstrated and design equations are developed. The STR design cedes only a small performance penalty to fully humidified designs and eases the requirement to develop PEMs capable of operating independent of water in conditions below 130oC. • Dynamic operation of the STR autohumidified fuel cell is investigated. Current ignition and extinction phenomena and multiple steady states are characterised. It is shown that through careful choice of the operating parameters the dynamic response of the autohumidified fuel cell can replicate that of hydrated feed systems. • A spatially resolved current density distribution and impedance analysis of a 20 cm2 autohumidified STR fuel cell system is undertaken. The analysis demonstrates that the STR fuel cell design reduces current density gradients in the fuel cell under reduced relative humidity operation and that the performance of the system is superior to a single channel serpentine system. Through its multi-scale approach, this thesis demonstrates the importance of considering the fuel cell as a system. New thermally and chemically stable fuel cell membranes which are capable of operating at temperatures above the glass transition temperature of current state of the art polymers are needed. Additionally, there is a requirement to operate fuel cells with atmospheric condition feed streams while maintaining the hydration of the membranes. Together, the sol-gel titanium phosphate membranes and autohumidified STR fuel cell developed fill this knowledge gap, leading to a closer realisation of a commercial fuel cell system.

Ohmic shorting through the membrane has been identified as one of the major failure modes in polymer electrolyte fuel cells (PEFC) [1]. Shorting occurs when electrons flow directly from the anode to the cathode instead of through the device being powered. Ohmic shorting not only can reduce the fuel cell performance, but also can lead to local heat generation in the vicinity of the short, causing membrane damage that can ultimately result in gas crossover failure. Two types of membrane shorts have been observed during the fuel cell testing: soft shorts and hard shorts. A soft short is a sub-critical short that results from the conductive carbon fibers or debris penetrating through the membrane. The soft shorts do not immediately lead to fuel cell failure; however, significant accumulation of soft shorts can reduce the overall cell resistance and compromise fuel cell durability through cell voltage degradation. A hard short is a critical short that is the result of significant heat release from an existing soft short. A hard short can directly lead to membrane crossover and cell failure. Hard shorts occur suddenly in an operating fuel cell stack where one cell develops a cell voltage reversal well below -1 V [2]. The present study is composed of two parts. The first is on the development of a test method to determine the density of soft shorts and their ohmic resistance that may lead to hard shorts when the adverse fuel cell operating conditions are met. The second part of the study is to investigate these adverse fuel cell operating conditions that lead to cell reversal and the potential hard shorts. The ultimate objective of the study is to prevent the fuel cell shorting failure through better material selection/designs and fuel cell operation controls. In the first part of this study, we use a current distribution circuit board [3] in a fixture that induces uniform compression over a 32 cm2 area of a sample that consists of a piece of proton exchange membrane or a membrane electrode assembly sandwiched between two gas diffusion layers. By incrementally increasing the compressive pressure and subjecting the sample to a voltage of 0.6 V, we can measure increasing shorting currents in some of the 0.5 cm2 current distribution segments. By de-convoluting the current density distribution measured in this experiment, the number and severity of each short can be identified and the robustness of various material sets against soft shorts can be compared. In the second part of the study, we stepwise dried out a single large-active-area fuel cell by decreasing the inlet gas dew points while under galvanostatic control. At a critical dew point, the cell potential dropped rapidly to reach a negative voltage that was limited to -1 V. Tests were conducted at various cell current densities and inlet temperatures, which showed that the corresponding cell resistance at the onset of rapid cell voltage drop decreases as the current density increases or as the temperature decreases. Good correlation is found between the cell resistance and the onset of cell reversal at various current densities. When the cell reversal limit of -1V was removed, we found that hard shorts can develop at a cell voltage around -3V, confirming the importance of operating the fuel cell within the operating window developed in this study. A.B. LaConti, M. Hamdan, R.C. McDonald, Mechanism of Membrane Degradation for PEMFCs, in Mechanisms of Membrane Degradation for PEMFCs, in: W. Vielstich, A. Lamn, H.A. Gasteiger (Eds), Handbook of Fuel Cells: Fundamentals, Technology and Applications, Vol. 3, John Wiley & Sons, New York, 2003, pp. 647–662.Gittleman, C. S., Coms, F. D., and Lai, Y. H., "Chapter 2: Membrane Durability: Physical and Chemical Degradation", Polymer Electrolyte Fuel Cell Degradation, Editors: Matthew M. Mench, E. Caglan Kumbur, T. Nejat Veziroglu, Elsevier (2012).J.J. Gagliardo, J.P. Owejan, T.A.Trabold, and T.W.Tighe, Nucl. Instrum. Meth. A, 605 (2009) 115-118.

Robust progress has been made in fuel cell technology since the previous edition of the Fuel Cell Handbook was published in January 1994. This Handbook provides a foundation in fuel cells for persons wanting a better understanding of the technology, its benefits, and the systems issues that influence its application. Trends in technology are discussed, including next-generation concepts that promise ultra high efficiency and low cost, while providing exceptionally clean power plant systems. Section 1 summarizes fuel cell progress since the last edition and includes existing power plant nameplate data. Section 2 addresses the thermodynamics of fuel cells to provide an understanding of fuel cell operation at two levels (basic and advanced). Sections 3 through 6 describe the four major fuel cell types and their performance based on cell operating conditions. The section on polymer electrolyte membrane fuel cells has been added to reflect their emergence as a significant fuel cell technology. Phosphoric acid, molten carbonate, and solid oxide fuel cell technology description sections have been updated from the previous edition. New information indicates that manufacturers have stayed with proven cell designs, focusing instead on advancing the system surrounding the fuel cell to lower life cycle costs. Section 7, Fuel Cell Systems, has been significantly revised to characterize near-term and next-generation fuel cell power plant systems at a conceptual level of detail. Section 8 provides examples of practical fuel cell system calculations. A list of fuel cell URLs is included in the Appendix. A new index assists the reader in locating specific information quickly.

Energy plays a very important role in human life. Every year, the demand for energy needs continues to increase and the majority of energy generation uses fossil fuels. So we need an energy source that is environmentally friendly. One of the environmentally friendly energy sources is a fuel cell. Fuel cells can produce electrical energy at a lower cost than the electrical energy generated by conventional power grids. In making a fuel cell system, a modeling is needed so that the fuel cell system can work properly and in accordance with the desired specifications. One method for modeling a fuel cell system is to use MATLAB. The use of a DC-DC boost converter with a properly designed closed loop PID controller has a very important role in regulating the PWM of the DC-DC boost converter switch and plays a very important role in controlling power regulation. In this research, a modeling analysis of NEXATM 1.2 kW hydrogen fuel cell with a DC-DC boost converter controlled by a PID controller was carried out for a compact Power Conditioning Unit (PCU) design. The purpose of this research is to model and analyze the characteristics of the performance of the hydrogen fuel cell system and the performance of the PID controller in regulating the DC-DC boost converter output voltage on the hydrogen fuel cell. The results showed that the performance of the hydrogen fuel cell was influenced by the pressure of oxygen gas, hydrogen, and temperature. The greater the value of oxygen gas pressure, hydrogen gas pressure, and temperature on the fuel cell, the greater the voltage and current output of the fuel cell. The simulation results show the fuel cell output voltage is 47.89 V with an error percentage of 4.22%, and the fuel cell output current is 23.94 A with an error percentage of 0.25%, and the fuel cell output power is 1147 W with an error percentage of 4.12%. The performance of the PID controller with the DC-DC boost converter in regulating the fuel cell output voltage is very good. This is indicated by the results of the response curve for the fuel cell output current, namely the value of rise time (tr) of 4 seconds, delay time (td) of 0.2 seconds, peak time (tp) of 4 seconds, settling time (ts) of 4 seconds, and a maximum overshoot (Mp) of 0%. For output voltage, the value of rise time (tr) is 4 seconds, delay time (td) is 0.2 seconds, peak time (tp) is 4 seconds, settling time (ts) is 4 seconds, and maximum overshoot (Mp) is 0% with the parameter value Proportional (P) of 0.001, Integral (I) of 10, and Derivative (D) of 0.

Energy storage and conversion is a very important link between the steps of energy production and energy consumption. Traditional fossil fuels are a natural and unsustainable energy storage medium with limited reserves and notorious pollution problems, therefore demanding a better choice to store and utilize the green and renewable energies in the future. Energy and environmental problems require a clean and efficient way of using the fuels. Fuel cell functions to efficiently convert oxidant and chemical energy accumulated in the fuel directly into DC electric, with the by-products of heat and water. Fuel cells, which are known as effective electrochemical converters, and electricity generation technology has gained attention due to the need for clean energy, the limitation of fossil fuel resources and the capability of a fuel cell to generate electricity without involving any moving mechanical part. The fuel cell technologies that received high interest for commercialization are polymer electrolyte membrane fuel cells (PEMFCs), solid oxide fuel cells (SOFCs), and direct methanol fuel cells (DMFCs). The optimum efficiency for the fuel cell is not bound by the principle of Carnot cycle compared to other traditional power machines that are generally based on thermal cycles such as gas turbines, steam turbines and internal combustion engines. However, the fuel cell applications have been restrained by the high cost needed to commercialize them. Researchers currently focus on the discovery of different materials and manufacturing methods to enhance fuel cell performance and simplify components of fuel cells. Fuel cell systems’ designs are utilized to reduce the costs of the membrane and improve cell efficiency, durability and reliability, allowing them to compete with the traditional combustion engine. In this review, we primarily analyze recent developments in fuel cells technologies and up-to-date modeling for PEMFCs, SOFCs and DMFCs.