Recent Trends in Fuel Cell Science and Technology PDF
Preview Recent Trends in Fuel Cell Science and Technology
Recent Trends in Fuel Cell Science and Technology Recent Trends in Fuel Cell Science and Technology Edited by SUDDHASATWA BASU Department of Chemical Engineering Indian Institute of Technology Delhi New Delhi-110 016, India y>0F*fa 4jj S p r i n g er Anamaya A CLP. catalogue record for the book is available from the Library of Congress ISBN 0-387-35537-5 (HB) Copublished by Springer 233 Spring Street, New York 10013, USA with Anamaya Publishers, New Delhi, India Sold and distributed in North, Central and South America by Springer, 233 Spring Street, New York, USA In all other countries, except India, sold and distributed by Springer, P.O. Box 322, 3300 AH Dordrecht, The Netherlands In India, sold and distributed by Anamaya Publishers F-154/2, Lado Sarai, New Delhi-110 030, India All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, Inc., 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Copyright © 2007 Anamaya Publishers, New Delhi, India springeronline.com Printed in India. In loving memory of my parents Professors N.M. Bose and N. Bose who nurtured and inspired me Preface Fuel cell science and technology is evolving fast for the past two decades as it is thought to be an efficient way of transforming chemical energy of hydrogen rich compounds to electrical energy. Although this idea of direct conversion of chemical energy to electrical energy was first demonstrated by Sir William Grove in 1839 using a fuel cell, it was only in the middle of the twentieth century when Bacon's pioneering work led to the use of fuel cell in space missions. The interest in commercialization of fuel cell for civilian use has caught up with government organizations and private corporations for the past decade on account of fluctuating oil prices and environmental concerns. It is well known that the conventional fossil fuel, which is a primary source of gasoline, is not going to last more than a hundred years in the face of ever-increasing demand in the developed and developing countries. Although the reserves of natural gas, coal and tar sands may last another two to three hundred years with the current rate of production, their conversion is not efficient and pollution-free. Thus, scientists all over the world have taken up fuel cell development work in their quest of solution to the energy crises looming largely on global population. This book aims to script the present status of the rapidly developing field of fuel cell science and technology. Since fuel cell (FC) science and technology is multidisciplinary in nature, contributions from the world experts in different areas of fuel cell technology are brought under one umbrella. There are different types of fuel cells, which work on different principles on the basis of different electro-reactions, temperatures, electrodes, electrolytes and fuels. Thus, instead of a single authored book, it is more appropriate to present the work carried out by various experts in the abovementioned areas. The reader should note that FC technology is fast developing towards commercialization and it is not possible to provide crucial details of the patented technology. However, this book provides sufficient information on FC technology so that new researchers from similar areas and those readers who are working in FC technology would be able to take up problems in the area of industry needs. Introduction to fuel cells and the common topics related to fuel cells, e.g. electro-analytical techniques and power conditioning, are included in the beginning and end of the book in their logical sequence. In- between, chapters describe the state-of-the-art of different types of fuel cell systems. Chapter 1 describes introduction to fuel cell technology and different types of fuel cells. Chapter 2 on electro-analytical techniques in fuel cell research and development deals with evaluation of kinetics of electro-catalytic reaction in half-cell, electro-analytical tools for single cell and stack design. Polymer electrolyte membrane fuel cell (PEMFC) has a promise of providing higher efficiency of the drive system and is regarded as the future motive power source for the transport sector. Thus, special emphasis is given on PEMFC. Chapters 3 to 5 discuss, elaborately, the latest developments in PEMFC, gas diffusion layer and water management in PEMFC. There are certain disadvantages associated with hydrogen such as large-scale and economical production of hydrogen from fossil fuel or other renewal route, emission of polluting gases as by-products during production of hydrogen from fossil fuel, dispensing and storage problems of hydrogen and safety issues. On the other hand, alcohols are produced from renewal sources, easy to handle, store and dispense. Use of alcohols directly into the fuel cell as fuel has been investigated for the past ten years. In Chapters 6 and 7, micro fuel cells, which are based on direct alcohol PEM fuel cell and direct alcohol alkaline fuel cell are presented. High temperature fuel cells are covered in Chapters 8 to 11 in the order of operating temperature. Phosphoric acid, molten carbonate fuel cells and direct conversion of coal in fuel cell are elaborately discussed in Chapters 8 to 10. Chapter 11 describes the principles, designs and state-of-the-art viii PREFACE of solid oxide fuel cells (SOFC). SOFCs, operated in the range of 700-1000°C with an efficiency of 60-80%, have a tremendous potential in the future as stationary power source in the order of kilowatt to megawatt range. Since it is operated at high temperature, material issues related to SOFC are discussed in Chapter 12. Chapter 13 covers the power conditioner system for fuel cell. Finally, future directions and challenges of fuel cell science and technology are presented in Chapter 14. SUDDHASATWA BASU Acknowledgements In writing this book, I was inspired by memories of working with my teachers in the area of Interfacial and Electrochemical Engineering and Fuel Cells. Generous funding and the platform provided by Indian Institute of Technology (IIT) Delhi and Ministry of Non-conventional Energy Sources, Government of India, has drawn me into the research and development of fuel cell technology. While covering the subject of fuel cell technology during teaching of electrokinetic transport course to the graduate students of IIT Delhi and in course of discussion with my research students, I was motivated to write a book on fuel cells. I have mentioned in the Preface why I have chosen to bring out an edited book whereby contributions from world experts in different areas of fuel cell technology are sought. I owe my thanks to all the contributors for sharing valuable state-of-the-art knowledge and experience on different types of fuel cells and associated topics. Reviewing chapters was not an easy task as they dealt with interdisciplinary fields of sciences and technologies. The objective of the book is fulfilled through patient and careful reading by myself and further revision carried out by the respective authors. Several occasions and informal discussions held with Dr. T.K. Roy, CMDC Ltd. and Dr. V.V. Krishnan, IIT Delhi were helpful in writing the last chapter on future directions of fuel cell science and technology. Encouraging discussions with my research students, Anil Verma, Amit K. Jha, Krishna V. Singh and Hiralal Pramanik brought confidence in believing in future potential of fuel cell technology. Finally, without the support of my wife and son, from whom I took away important family time, this book would not have been published in its present form. SUDDHASATWA BASU Contents Preface vii Acknowledgements ix 1. Introduction to Fuel Cells 1 R.K. Shah 2. Electro-Analytical Techniques in Fuel Cell Research and Development 10 Manikandan Ramani 3. Polymer Electrolyte Membrane Fuel Cell 40 K.S. Dhathathreyan and N. Rajalakshmi 4. Fundamentals of Gas Diffusion Layers in PEM Fuel Cells 116 Virendra K. Mathur and Jim Crawford 5. Water Problem in PEMFC 129 Kohei Ito 6. Micro Fuel Cells 137 S. Venugopalan 7. Direct Alcohol and Borohydride Alkaline Fuel Cells 157 Anil Verma and Suddhasatwa Basu 8. Phosphoric Acid Fuel Cell Technology 188 Suman Roy Choudhury 9. Carbonate Fuel Cell: Principles and Applications 217 Hossein Ghezel-Ayagh, Mohammad Farooque and Hansraj C. Maru 10. Direct Conversion of Coal Derived Carbon in Fuel Cells 248 John F Cooper 11. Solid Oxide Fuel Cells: Principles, Designs and State-of-the-Art in Industries 267 Roberto Bove 12. Materials for Solid Oxide Fuel Cells 286 Rajendra N. Basu 13. Fuel Cell Power-Conditioning Systems 332 Sudip K. Mazumder 14. Future Directions of Fuel Cell Science and Technology 356 Suddhasatwa Basu INDEX 367 Recent Trends in Fuel Cell Science and Technology Edited by S. Basu Anamaya Publishers, New Delhi, India 1. Introduction to Fuel Cells R.K. Shah Subros Ltd., Noida-201304, India E-mail: rkshah@gmail-comt 1. Introduction A fuel cell is an electrochemical device (a galvanic cell) which converts free energy of a chemical reaction into electrical energy (electricity); byproducts are heat and water/steam if hydrogen and air are the reactants; in some fuel cell types, the additional byproducts may be carbon dioxide and leftover lower forms of hydrocarbons depending on the fossil fuels used. There is no combustion in this process and hence no NO^ are generated. Sulfur is poison to all fuel cells so it must be removed from any fuel before feeding to any fuel cell type; hence, no SO^ are generated. A fuel cell produces electricity on demand continuously as long as the fuel and oxidant are supplied. For reference, primary cell or battery is also an electrochemical energy producing device (one-way chemical reaction producing electricity) and needs to throw away once the battery is discharged. A rechargeable or secondary battery is an electrochemical energy storage device having reversible chemical reaction producing or using electricity, but it also has a limited life. The components of a fuel cell are anode, anodic catalyst layer, electrolyte, cathodic catalyst layer, cathode, bipolar plates/interconnects and sometimes gaskets for sealing/preventing leakage of gases between anode and cathode. The stack of such fuel cells (a repeated stack of such components) is connected in series/parallel connections to yield the desired voltage and current. The anode and cathode consist of porous gas diffusion layers, usually made of highly electron conductivity materials (and having zero proton conductivity theoretically) such as porous graphite thin layers. One of the most common catalysts is platinum for low temperature fuel cells and nickel for high temperature fuel cells, and other materials depending on the fuel cell type. The electrolyte is made of such material that it provides high proton conductivity and theoretically zero electron conductivity. The charge carriers (from the anode to the cathode or vice versa) are different depending on the type of the fuel cells. Some details are presented in Table 1. The bipolar plates (or interconnects) collect the electrical current as well as distribute and separate reactive gases in the fuel cell stack. The anode reaction in fuel cerls is either direct oxidation of hydrogen, or methanol or indirect oxidation via a reforming step for hydrocarbon fuels. The cathode reaction is oxygen reduction from air in most fuel cells. For hydrogen/oxygen (air) fuel cells, the overall reaction is H + \ 0 -> H 0 with AG = -237 kJ/mol (1) 2 2 2 where AG is the change in Gibbs free energy of formation. The product of this reaction is water released at cathode or anode depending on the type of the fuel cell. The theoretical voltage E° for an ideal H /0 fuel 2 2 Formerly at Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA.
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