Preface

The most famous and dramatic articulation of the principle of population growth outstripping resources was made toward the end of the 18th century by Reverend Thomas Malthus, a British political economist. Rev. Malthus was, of course, talking about food resources, postulating that populations have a geometric growth pattern and are bound to run out of food resources that grow only arithmetically, ultimately leading to a disaster involving mass starvation and deaths. This hypothesis was a major influence for many governments of the time in formulating their policies that were not necessarily beneficial to their populations.

In the intervening period since Rev. Malthus propounded his theory, the human population has increased by leaps and bounds, and despite occasional, localized episodes of famine and starvation, the dire prediction of a widespread Malthusian catastrophe has never materialized. Much of the success in averting this catastrophe is due to human ingenuity in harnessing new forms of energy, which is truly the master resource that enables the creation and exploitation of other resources. Development of these—primarily fossil energy resources—and the Industrial Revolution fueled by these resources have enabled populations the world over to thrive, grow, and enjoy an unparalleled standard of living compared to agrarian societies of the past.

Accelerated exploitation of fossil resources has reignited the question of resource limitations, and the 20th century saw an emergence of neo-Malthusianism that seeks to apply Malthusian concepts to all resources, including energy resources. Notwithstanding the successes in the prediction of exhaustion of localized fossil resources, global exhaustion of these resources remains questionable. However, climate change concerns portend an inevitable phase-out of fossil fuels and their displacement by renewable primary energy sources that by their very nature are untouched by any Malthusian constraints.

A sustainable energy future requires a substantial growth in renewable energy systems to replace the current energy mix. These systems provide a solution to the problem of growing carbon emissions and consequent climate change that threatens human civilization in its present form. Development of these renewable energy systems requires engineers and other technical professionals to be knowledgeable in harnessing the primary energy resources and converting those to energy carriers that can be integrated with the current energy infrastructure.

This book has grown out of the need to have a text that would provide the necessary theoretical foundation and exposure to practical systems to educate these technical professionals. The motivation was to create a book that will serve engineering students and practitioners engaged in the energy field. Despite the considerable literature regarding the technologies employed in the renewable energy field, a comprehensive text that presents the fundamental engineering principles and their applications in renewable energy technologies is currently not available. This text seeks to fill this unique niche and will be invaluable in preparing renewable energy professionals for responding to the current and future challenges in the sustainable growth of renewable energy technology.

Chapter 1, Introduction to Energy Systems, presents an overview of the energy systems and the status and limitations/challenges faced by the current energy mix leading to the vision of a renewable energy future. Various primary renewable sources are described in Chapter 2, Renewable Energy Sources, along with the nature of operations and processes involved in the energy transformations to electricity and other energy carriers. Chapter 3, Transformations and Chemical Processes in Solar Energy Systems, focuses specifically on the transformations of solar energy, while transformations of biomass energy are discussed in Chapter 4, Transformations and Chemical Processes in Biomass Energy Systems. Transformations of geothermal and other primary energy sources that are mainly mechanical (hydro, wind, and ocean) are presented in Chapter 5, Transformations and Chemical Processes in Mechanical, Geothermal, and Ocean Energy Systems.

Energy systems of the future will almost certainly be hybrid, featuring a combination of primary energy sources and a provision for energy storage. These hybrid energy systems are discussed in Chapter 6, Hybrid Energy Systems, with an emphasis on the different energy storage alternatives. Finally, principles of techno-economic analysis of renewable energy systems are presented in Chapter 7, Techno-Economic Analysis of Renewable Energy Systems, to provide the reader with an understanding of the factors that inform the energy policy.

The field of renewable energy can be visualized as a vast canvas with continually evolving scenery due to the rapid technological developments taking place in its every aspect. A particular challenge in the writing of this book, as it will be for any book on renewable energy, was to capture the latest scenery while maintaining the relevance for future development. The approach in this book in dealing with this challenge has involved focusing on the fundamental scientific and technological principles and explaining/analyzing the transformations in the context of these underlying principles. Every attempt has been made to incorporate the latest developments by consulting the state-of-the-art literature. Sufficient references are provided for the reader to explore any particular topic in greater detail. It is expected that this approach will serve readers well in their efforts to stay up to date with the most recent developments in the renewable energy field.

For a student, this book is a comprehensive introduction to the field of renewable energy, not only in terms of technical principles but also policy perspectives. For an instructor, it provides a framework for teaching the fundamentals and essential elements while offering flexibility to delve deeper into specific topics. And for the practitioners, it serves as a refresher and ready reference for dealing with the technological and socio-economic challenges they are facing in the implementation of a particular renewable energy system.

Human societies are marching inexorably towards a renewable energy future. It is my sincere hope that this book contributes to these efforts and helps accelerate, howsoever slightly it may be, the transition to renewable energy systems.

—Vivek P. Utgikar
Moscow, Idaho, United States
May 2021