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RENEWABLE ENERGY FROM THE OCEAN THE JOHNS HOPKINS UNIVERSITY Applied Physics Laboratory Series In Science and Engineering SERIES EDITOR JOHN R. APEL WILLIAM H. AVERY AND CHIH Wu. Renewable Energy from the Ocean. A Guide to OTEC BRUCE I. BLUM. Software Engineering: A Holistic View ROBERT M. FRISTROM. Flame Structure and Processes RICHARD A. HENLE AND BORIS W. KUVSHINOFF. Desktop Computers: In Perspective VINCENT L. PISACANE AND ROBERT C. MOORE (EDS.). Fundamentals of Space Systems RENEWABLE ENERGY FROM THE OCEAN A Guide to OTEC William H. Avery DIRECTOR (RETIRED) Ocean Energy Programs The Johns Hopkins University Applied Physics Laboratory and Chih Wu PROFESSOR Department of Mechanical Engineering United States Naval Academy New York Oxford OXFORD UNIVERSITY PRESS 1994 Oxford University Press Oxford New York Toronto Delhi Bombay Calcutta Madras Karachi Kuala Lumpur Singapore Hong Kong Tokyo Nairobi Dar es Salaam Cape Town Melbourne Auckland Madrid and associated companies in Berlin Ibadan Copyright © 1994 by Oxford University Press, Inc. Published by Oxford University Press, Inc. 200 Madison Avenue, New York, New York 10016 Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Avery, William H. Renewable energy from the ocean : a guide to OTEC / William H. Avery and Chih Wu. p. cm. — (Johns Hopkins University/ Applied Laboratory series in science and engineering) Includes bibliographical references and index. ISBN 049-507199-9 1. Ocean thermal power plants I. Wu, Chih, 1936- II. Title. III. Series. TK1073.A94 1993 621.31'244—dc20 93-20885 987654321 Printed in the United States of America on acid-free paper To the Pioneers This page intentionally left blank Foreword All too often when societies face crises involving population, energy, resources, or environment they procrastinate until the problem can no longer be ignored. This phase is followed by a period in which the society turns to panaceas or palliatives. These cosmetic solutions mask and defer the problem until a new crisis erupts in a new mode with heightened potential for catastrophe. Happily, some real solutions to past problems have emerged. These solutions resulted from the work of problem solvers who recognized that there were no short-term answers. The energy-environmental crisis with which the world is wrestling, and has wrestled for more than 2 decades, when coupled with the population explosion, will be the most chronic and crucial of these world crises. We are now aware that the panaceas of direct solar conversion, nuclear energy, and natural gas, even with the palliatives of energy conservation, are ineffective solutions to the onset of global warming. World competition surrounds the depleting pools of oil like a crowd of thirsting dinosaurs. Once again the establishment machinery is in motion to pump new life into short-term solutions. But the readers of this book will recognize that long-term solutions are an absolute necessity. One such solution is the development of ocean thermal energy and the transportable nonpolluting fuels that can be obtained from this large renewable reservoir. Dr. William Avery and his colleagues were among the few teams who, in 1973, asked themselves the scientific question—how best to meet the energy crisis— without any preconceived notion or prejudice about what the solution might be. Their long experience in the development of advanced technology made them familiar with the scientific approach to innovation that strips away the conventional wisdom of the past and reduces the problem to one of fundamental physics and geophysics. This approach led to the identification of ocean thermal energy conversion as a plentiful and practical way of alleviating world energy needs by utilizing solar energy stored in the vast tropical oceans that is available night and day, throughout the year. Once identified, there was the analytical and experimental documentation of practical ways of transferring this thermal energy into electrical energy and from electrical energy to chemical energy in the form of hydrogen, ammonia, or methanol. Each step required consideration of economics and environment as well as technology with recognition that solutions must be economically viable and environmentally sustainable. viii As early as 1975 A very and his colleagues had identified the sea-based manufacture of ammonia as an economically and environmentally feasible energy option, but the implementation of this option was held back by the availability of "low-cost fuel." The economic and environmental impacts of dependence on Middle East fuel supplies were disregarded. As a consequence the team was reduced in size and then all but abandoned. Avery and Wu have pooled the knowledge gained and in this book have carefully and meticulously documented the studies and experimental results of the small band of investigators who persisted in the exploration of this vital resource. Who would deny that we are once again in the middle of an energy/ environmental/population crisis? Now, however, a critical mass of investigators employing the waters of Hawaii as their laboratory have developed the proof that ocean thermal energy and its by-products are an important element in a rational and environmentally sustainable solution. This important work is being recognized. Relevant pilot projects now exist in Britain and Hawaii, and developments are under serious consideration in the Cook Islands, the Marshall Islands, and the Cape Verde Islands. The entrepreneurs who have independently entered the development process will soon be joined by others. This book will be their bible. John P. Craven Former Dean of Marine Engineering University of Hawaii Preface The upper layers of the tropical oceans are a vast reservoir of warm water that is held at a temperature near 27°C (80°F) by a balance between the absorption of heat from the sun and the loss of heat by evaporation, convection, and long-wavelength radiation. On an average day, the water near the surface absorbs more heat from the sun in one square mile of ocean area than could be produced by burning 7000 barrels of oil. For the whole tropical ocean area, the solar energy absorbed per day by the surface waters is more than 10,000 times the heat content of the daily oil consumption of the United States. A practical and economical technology for converting even 0.01 % of the absorbed solar energy into electricity or fuel in a form suitable for delivery to consumers on land could have a profound impact on world energy availability and economics. The technology called ocean thermal energy conversion (OTEC) fulfills the technical and economic requirements for productive use of the solar energy continually absorbed by the oceans. However, the unfamiliarity of the OTEC concept and misconceptions about the difficulty of implementing it have slowed the development of interest by industry and government. This book presents the scientific and engineering fundamentals of OTEC technology in a context that will make clear how this technology can be applied in a practical way to a future world economy based on renewable, nonpolluting energy sources. The status of OTEC development programs is presented, and technical and cost information are provided from which valid estimates can be made of OTEC plant investment requirements and delivered costs of OTEC fuels, chemicals, and electric power. The book shows that the technology base for OTEC is sufficiently well established for large-scale demonstration plants to be built as forerunners to commercial plants and plantships that will be economically attractive and environmentally benign. The manufacture of OTEC plants and plantships can draw on the talents and facilities available in the U.S. chemical and power production industries and in shipyards, steel companies, and concrete construction firms. OTEC commercialization offers many new employment opportunities, including large requirements for low-skilled laborers. OTEC-produced fuels can be an inexhaustible substitute for petroleum-based fuels and could ultimately be produced in quantities and at costs that would make it practical for this technology to supply a large part of the energy needs of the world. After an introductory overview, the book reviews the history of OTEC development and presents a discussion of the scientific and engineering fundamentals of the technology, including the technical options for electrical and chemical energy delivery. The engineering status, projected costs (which are favorable in X comparison with other renewable energy alternatives), manufacturing capabilities, and potential markets are then discussed. The book concludes with a critical examination of the economic implications and prospects of OTEC, including the environmental and social impacts of its large-scale commercial development. Acknowledgments A few farseeing and dedicated individuals created programs in the early 1970s that expanded rapidly to establish OTEC technology as a renewable energy resource with the potential to make major contributions to world requirements for safe, benign, and inexhaustible energy sources. The senior author (WHA) has been privileged to know and have the support of the early American investigators, and to play a part in the efforts of the large teams of scientists and engineers who worked to bring OTEC into operation in the early 1980s. Unfortunately only a small number of those whose contributions were vital to the success of the technical program can be given credit for their contributions. Since team efforts were the rule, it is appropriate to recognize individuals in conjunction with the organizations that supported their work. To all of them we are grateful. J. Hilbert Anderson, Sea Solar Power, Inc.: His innovative engineering concepts and tireless enthusiasm brought OTEC to the attention of the engineering community and inspired future efforts worldwide. Clarence Zener, Carnegie-Mellon University: His physical insight into energy options led to his interest in OTEC, and his international prestige created significant support for OTEC within the National Science Foundation, ERDA, and, finally, DOE. Robert Cohen, NSF, ERDA, and DOE: He was able to maintain funding for OTEC despite unenthusiastic support from the federal bureaucracy and the energy establishment. Marvin Pitkin, MARAD: His recognition of the commercial promise of OTEC brought funding from the U.S. Maritime Administration (MARAD) for vital studies of the shipbuilding and commercialization requirements. Eugene Schorsch: His interest in OTEC gained the support of the management of the Sun Shipbuilding and Drydock Company, who, at their expense, assigned a team to work with JHU/APL to define the marine engineering requirements and conceptual design of a concrete barge that would minimize OTEC shipbuilding costs. John Craven, University of Hawaii: His deep understanding of ocean science and engineering combined with political prowess induced the government of Hawaii to recognize the unique capabilities of Hawaii to become a world center for renewable energy development, with particular emphasis on OTEC. This led to the establishment of the Natural Energy Laboratory in Hawaii. The Lockheed team: Under the leadership of James Wentzel and Lloyd Trimble, Lockheed, with support from the State of Hawaii and industrial partners, built and operated the Mini-OTEC vessel with private funding, demonstrating for the first time net power production from solar thermal energy stored in the oceans.