Preface
Renewable energy sources such as wind turbines and solar panels for electricity generation have become commonplace in our society. Their aim is to supply energy that is free from carbon dioxide production while sustainable and not dependent on a finite energy supply. Unfortunately their full potential is reduced by their intermittency. For these and other developing renewable technologies, such as tidal current energy and wave energy, to make a real difference we need to find effective ways to store this energy. This book is a showcase for the current state of the different methods that are being explored to store energy and make it available not only when the Sun is shining, the wind is blowing, the tides flowing, the sea currents moving or when the waves are breaking. These new storage methods will also be useful in times when demand for electricity is low and electricity can be bought cheaply and stored until demand rises and the stored energy can be used. At present the chief way of storing energy is through pumped hydroelectric storage. Most countries have now exhausted the places where large reservoirs can be built so this new focus on storing energy is both timely and necessary as the world moves towards sustainable carbon-free energy.
Some chapters in the book are concerned with developments of well-known energy storage techniques, others are concerned with new techniques which are being tested and researched for the first time, and a few involve techniques which have yet to leave the drawing board. Unfortunately a few interesting and novel processes are missing as authors were unavailable to write the chapters. One process is that of superconducting magnetic energy storage (SMES) which has recently been reviewed by Weijia Yuan and Min Zhang in A Handbook of Clean Energy System published by Wiley (2015) (DOI: 10.1002/9781118991978.hces210). Two other links are: http://link.springer.com/book/10.1007%2F978-0-85729-742-6 and http://onlinelibrary.wiley.com/doi/10.1002/9781118991978.hces210/abstract. Facilities for SMES exist all round the world for use in power quality control and for grid stabilization and units of 1 MW h are not uncommon.
Another technology which is not represented here is that involving super-capacitors which are very effective at relatively small-scale energy storage (thus in competition with batteries) and which is particularly useful in transport vehicles. Its applications are reviewed by Yank, Yeh, and Ramea et al. of the University of California, Davis at: http://www.its.ucdavis.edu/wp-content/themes/ucdavis/pubs/download_pdf (document 2014-UCD-ITS-RR-14-04).
A third process not covered in this volume is the pumped heat electrical energy storage system currently being developed by Isentropic Ltd. in Hampshire, UK. This is a grid scale storage system, and the short term goal is to develop a 1.5 MW unit. The method has great promise but has yet to be commercially available. A good introduction to the topic is the paper by Derues, Ruer, Marty and Fourmigue in Applied Thermal Engineering, 2010; 30:425–432. Yet another explanation of the process is given by staff of Isentropic Ltd. http://www.isentropic.co.uk/our-phes-technology.
Our book Storing Energy: with Special Reference to Renewable Energy Sources, is a natural follow-up to Future Energy: Improved Sustainable and Clean Options for our Planet (2nd ed.), which was published by Elsevier in 2014. In Future Energy the case was made for developing new and sustainable energy sources in the light of climate change and increasing levels of greenhouse gases. In many ways, Storing Energy also goes hand in hand with another book we published recently: Climate Change: Observed Impacts on Planet Earth (2nd ed.) (Elsevier 2015).
The present book is divided into four sections, namely an Introduction; Electrical Energy Storage Techniques; Integration; and International Issues and the Politics of Introducing Renewable Energy Schemes. The Electrical Energy Storage section is divided into further sections headed: Gravitational, Mechanical, and Thermomechanical; Electrical; Thermal; and Chemical. The Gravitational, Mechanical, and Thermomechanical storage methods include chapters on: pumped hydroelectricity storage (PHES) as well as novel hydroelectricity processes; liquid air (LAES); compressed air (CAES); pumped hydro combined with compressed air; and finally advanced rail energy storage (ARES). The Electrical section has chapters on: rechargeable batteries and vanadium redox flow batteries. The Thermal section has chapters on: phase changes; solar ponds; and sensible thermal energy storage and the Chemical section includes chapters on: hydrogen and water electrolysis; chemical reactions including zeolite–water reactions; power to gas; traditional energy storage (gas oil and coal) and large scale hydrogen storage. The Integration chapters are on network integration, smart grids and off-grid energy. The three chapters in the section on International Issues and the Politics of Introducing Renewable Energy are: on energy storage in China; energy storage worldwide; and on the politics of investing in renewable energy.
Many governments and people of influence throughout the world are supporting the drive to reduce our dependency on fossil fuels with interesting and innovative programmes. One such programme is the Global Apollo Programme, spearheaded by Sir David King, which calls for £15 × 109 (£15 billion) a year to be spent on research, development and demonstration of green energy and energy storage. Significantly this amount is the same, in today’s money that the US Apollo programme spent in putting astronauts on the moon. Professor Martin Rees, former head of the Royal Society and another member of the Apollo group, explains the reason for using the name Apollo: “NASA showed how a stupendous goal could be achieved, amazingly fast, if the will and the resources are there.”
This book has been produced in order to allow the reader to have an understanding and insight into a vital aspect of our future use of energy—its storage. The final decision as to which option should be developed in a country or region must take into account many factors including: topography, for example, are there suitable sites for reservoirs to tap into PHES?; are there convenient salt caverns available for gas storage?; is the amount of sunlight available sufficient?; is it possible to take advantage of thermal energy storage?; is the chemical industry infrastructure sufficiently mature?; is it possible to install electrolysis plants for hydrogen production or develop chemical reaction storage or install a sophisticated battery system?; is the density of population important and should off-grid technologies be incorporated or can network integration and smart grids be used?
It is also to be hoped that the book will act as a springboard for new developments. One way that this can take place is through contact between readers and authors and to this effect mail addresses of the authors have been included.
The book is supported by IUPAC through its Physical Chemistry Division and both the logos of IUPAC, and our publisher Elsevier, appear on the front cover. The adherence of IUPAC to the International System of Quantities through its Interdivisional Committee for Terminology, Nomenclature and Symbols (ICTNS), is reflected in the book with the use of SI Units throughout. The index notation is used to remove any ambiguities; for example, billion and trillion are written as 109 and 1012, respectively. To further remove any ambiguities the concept of the quantity calculus is used. It is based on the equation: physical quantity = number × unit. To give an example, power = 200 W and hence, 200 = power/W. This is of particular importance in the headings of tables and the labelling of graph axes.
This volume is unique in the genre of books of related interests in that each chapter of Storing Energy has been written by an expert scientist or engineer, working in the field. Authors have been chosen for their expertise in their respective fields and come from ten countries: Australia, Austria, Canada, China, France, Germany, South Africa, Spain, United Kingdom, and the United States. Most of the authors come from developed countries as most of the research and development in this fast moving field, presently, come from these countries. We look forward to the future when new approaches to storing energy from scientists and engineers working in developing countries will be developed which focus on their local conditions.
A vital concern related to future energy and storing energy is: what is to be done when it appears that politicians misunderstand or ignore and corporations overlook, the realities of climate change and the importance of renewable energy sources? The solution lies in sound scientific data and education. As educators we believe that only a sustained grassroots movement to educate citizens, politicians and corporate leaders of the world has any hope of success. This book is part of this aim. It presents options for readers to consider and we hope that not only students, teachers, professors, and researchers of renewable energy, but also politicians, government decision makers, captains of industry, corporate leaders, journalists, editors, and all interested people, will read the book, take heed of its contents and absorb the underlying message that renewable energy sources are our future and storing energy is a vital part of it.
I wish to thank all 59 authors and coauthors for their cooperation, help and especially for writing their chapters. It has been a pleasure working with each and every one of the authors. I thank my wife Valerie for all the help she has given me over these long months of putting the book together. I also wish to thank Elsevier for their professionalism and help in producing this well presented volume. Finally I wish to thank Professor Ron Weir of IUPACs Interdivisional Committee for Terminology, Nomenclature and Symbols for his help and advice.