Energy, Ecology, and the Environment PDF
Preview Energy, Ecology, and the Environment
E n e r g y, E c o l o g y, a nd t he E n v i r o n m e nt Richard Wilson Harvard University William J. Jones Massachusetts Institute of Technology Copyright © 1974, by Academic Press, Inc. all rights reserved. no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. A C A D E M IC P R E S S, I N C. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by A C A D E M IC P R E S S, I N C. ( L O N D O N) L T D. 24/28 Oval Road. London NW1 Library of Congress Catalog Card Number: 74-10064 ISBN 0 - 1 2 - 7 5 7 5 5 0 -2 PRINTED IN THE UNITED STATES OF AMERICA Cover photograph courtesy of Portland General Electric Power Co., Portland, Oregon List of Technical Notes 1-1 Doubling Time 6 1-2 Newton's Laws 11 1-3 The Metric System; Units 14 2-1 Fahrenheit to Centigrade 25 2-2 Waves and the Electromagnetic Spectrum 28 2-3 Photocells 30 2-4 The Carnot Engine and Efficiency 33 2-5 Interference Filters 35 2-6 Tidal Power 41 3-1 The Galvanic Cells: Electrical Storage Devices 85 3-2 Mechanical-Energy Storage, the Flywheel 87 4-1 Black Bodies and Absolute Zero 102 4-2 Specific Heat 110 4-3 Latent Heats 118 4-4 The Coriolis Force 121 4-5 The Laws of Thermodynamics 129 5-1 The Concept of Charge 139 5-2 Electric Current, Conductivity, and Resistance 140 5-3 Notation for Nuclear Reactions 148 5-4 Radioactivity and Half-Life 150 5-5 Delayed Neutrons 156 5-6 159 5-7 Ionization and Ionizing Radiation 164 5-8 Magnetic Containment and Stability 166 8-1 Stokes' Law 202 8-2 Catalysis 204 8-3 The Spread of Pollution; Chimneys 207 9-1 The Inverse Square Law 247 12-1 The Fuel Cell 313 xi List of Worksheets 1-1 Energy Consumption: Projections 6a 1-2 Energy Consumption and Population Growth 6c 1-3 Newton's Law; Work and Kinetic Energy 16a 1-4 Conservation of Energy 20a 2-1 Solar Farms 32a 2-2 Tidal Power 44a 2-3 The Amount of Heat within the Earth 46a 3-1 The Cost of Food Energy 76a 3-2 Personal Energy Resource Consumption 80a 3-3 The Pumped-Storage Generating Plant 88a 4-1 The Earth as a Black Body 102a 4-2 Specific Heat 110 4-3 Latent Heats 129 5-1 Binding Energy 146a 5-2 The Energy in a Pound of Uranium 148a 6-1 The Accident Limit Line 180a 7-1 Strip-Mining 194a 8-1 Lifetime of SO2 over Chicago 208a xii Preface "Energy, Ecology, and the Environment,11 the title of this book, is a concise statement of conflicting interests. Extraction of the sources of energy and the methods of harnessing and utilizing energy can adversely affect the ecology and environment of our world. Highly developed nations depend on cheap energy to maintain their standard of living. The hopes of the developing countries are based on the similar harnessing of cheap energy and spreading of its benefits. Only if we are careful can we minimize damage to the ecology and, at the same time, maintain and achieve the above. In the United States, there is an apt example of conflict. The southern hot-weather states after World War II developed as an indus trial and cultural force with the widespread introduction of air con ditioning. In the hottest parts of the year, air conditioning is as necessary in the South as is heat in the North during the winter months. Air conditioning, with the common compression- or absorption-type unit, is unfortunately one of the most inefficient ways of using energy to condition working and living space. We might be able to develop more efficient ways of using energy for this purpose, but barring a total shortage of energy, it is unlikely that we will, as a general national policy, discontinue the use of air conditioning where it is most needed. To do so would drastically affect the economy and structure of this country. xiii Preface Aside from the question of how much energy is available, we know about pollution caused by emissions from electrical generating plants, effluent from extraction of fuels, and the like. We shall discuss all of these matters in detail and endeavor to do so from a foundation of facts. This is a book dealing with science and technology. Most of the material in the book is text. Technical Notes in the body of the book may be skipped without effect on the continuity of the text. They pro vide detailed information about scientific principles or technology. Some of these Technical Notes require the use of mathematics, but all can be used as a point of departure for the instructor who may want to add special topics to the course. References are provided to encourage further reading. In addition to covering a subject of importance to us all, this book provides the reader with a good idea of how physicists and engineers approach problems. The reader is asked to make "ball park" estimates to show whether or not an effect is important, in some cases where he might not even realize he was capable of so doing. The reader is taught to distinguish between goals that are theoretically possible but not yet technologically feasible, and those that violate basic physical princi ples. He is shown how to find solid data. The book also reveals something about the social concerns of sci entists. This book is dedicated to our wives, Dorothy J. and Andree W., who have lived with it more than the reader will have to. Several persons have helped us with criticism and suggestions. Special note is made of the contributions of Academic Press. xiv 1 Energy INTRODUCTION Energy is a mainstay of our economic life. Five percent of our Gross National Product is spent on electricity, more than twenty-five percent on automobiles, their use, and their maintenance. All indica tions are that our demands for energy will increase. Yet we now see that our fuel supplies such as gasoline and electricity will have to be rationed in the very near future... 1974, 1975, 1976? Some experts say that continual exploration will find new oil and gas fields or that nuclear power, if rapidly brought into the picture, will go a long way toward forestalling the need to impose restrictions on the use of energy. Other experts say that the price we will have to pay in terms of environmental damage and health hazards for these immediate solutions will be great. Whenever questions of energy resources come up, so too do ques tions of technology, economics, social need, and environmental effects. Which, in each case, is the more important factor? Too often each spokesman seems to work with a different set of facts, and different numbers for these effects. What are the facts? How accurately can we project the amount of petroleum that remains in the Earth? How safe are nuclear power reac tors? Are they as accident proof as some say, or as vulnerable as 1 1. Energy others say? Is there such a concept as "absolutely safe"? Are other forms of fuel any better than nuclear fuels? How can the scientist and engineer fit human and economic factors into his equations? How does the concerned citizen determine whether industry is making real istic projections for the long- and short-term benefit of society or whether a political leader may be just accepting the popular viewpoint on an issue? We shall try to work toward the answers to these questions. In the process we will develop a formal definition of energy and become familiar with the terminology of the scientist and engineer. This aspect of the subject will not prove particularly difficult since most of the terms fit our intuitive everyday use of the same words. We shall see how important it is to decide what data we need and to express this as quantitatively (numerically) as we can; then we will be able to compare the cost of obtaining energy, of the associated environmental dislocation, and of loss of life in accident, with the gain to society of easily available energy. When we can express the data quantitatively, decisions become easier. They become hard to make when the data is quantitatively unreliable. ENERGY CONSUMPTION: A BRIEF HISTORY Early in geologic time our mineral resources and fossil fuels were laid down in limited, or finite, amounts. Coal, like petroleum and natural gas, is a fossil fuel, a fuel believed to have evolved from buried organic matter over the course of thousands of centuries through a combination of chemical changes and intense pressures from the tons of earth over it. Once used, we cannot expect these minerals and fuels to be replaced. Figure 1-1 shows the various periods of geologic time. Man has lived in the latter part of this time and is now rapidly consuming these resources. [Refer to Worksheets 1-1 and 1-2.] Man's use of energy has grown slowly. At first it was limited to what he ate: then as now about 2000 Calories* per day. This energy was obtained from the sun via animal and vegetable life. As man learned to control his environment to some extent, he tamed animals and used them to bear a number of his burdens of labor. He invented the wheel to improve his efficiency in energy use. As he did so, he obtained an advantage over other species and was able to divert more and more of the world's resources to his use. The * The Calorie is defined in Chapter III. [See Worksheet 3-1.] 2 Energy Consumption: A Brief History human population increased quite slowly until the beginning of the industrial revolution, about 400 years ago; at that time several marked changes came about. Wood had long been burned for heating and cooking, but its use was limited by the supply. By 1700 the wood of England was essentially all cut, and the population was saved from being exceptionally cold by the discovery of coal near the northeast coast of England, near Newcastle, in the 12th century. The development of coal mining followed. The use of various power sources for motive power developed more slowly. Animal hauling, wind for sails in ships, and the steam engine came about over a long period of time. The water wheel and the windmill were used for milling quite early. Hero's aeolipile, a simple steam engine demonstrated to the ancient Greeks 1900 years ago, was regarded as a toy rather than a machine. The steam engine of James Watt (lab assistant to the Professor at the Physics Department, University of Glasgow) was first used in mining, to pump out water and to haul men and coal up from the pits. By 1800, all pit mines in England were so equipped. The use of the steam engine for motive power appeared in 1828, first on the mine rail roads, which had previously employed horses. It was so successful that railroads expanded all over the world within half a century. Two further important steps took place soon thereafter. The first, Michael Faraday's discovery of electromagnetic induction, was followed at the end of the century by the electric motor and dynamo. Its application to electric trains and streetcars came very fast, by about 1890. Edison's electric light was, perhaps, even more profound in its effect on society; but the electric light is not a major factor in energy consumption. The second step was the invention of the internal combustion engine, combined with the discovery of large quantities of oil. The internal combustion engine has shown itself to be extraordinarily robust and reliable; gasoline (or fuel oil) has a very high heat content. In all this time, a growth in human population has taken place. Early man appeared nearly a million years ago. How fast did his numbers increase? Let us look at the conservative side of things, and at the · same time introduce the concept of doubling time. If man doubled his population regularly every 30,000 years, he would have increased from, shall we say, two to four hundred million in half a million years. Four hundred million was the Earth's popula tion in the year 1600. Yet, in the last two hundred years, the world's population has doubled every sixty years.' With this growth in popula tion has come a demand for energy; indeed, it can be argued that without even more energy per person the population increase would not have been possible. 3 Time- 1— • 5 billion • EARTH FORMED · 2.6 billion 12 BILLION YEARS AGO.-\V:.;. '·\\ ' '' (13 TO 7 BILLION YEARS AGO?) . 500,000 YEARS AGO " -Time 1 milll ion 13 million (0.5 to 3 million)- -Pliocene period- 600,000 _or Nebraskan I ,\acial period large carnivores grazing mammals Early Man (400,000 to, 420,000 300,000 220H,000 Riss or lllinoian 150,000 V 450,000)^ Mindel or Kansan glacial period glacial period | chopping tools crude stone and choppers axes PITHECANTHROPUS (Beginnings of Homo Sapiens?) 10,000 YEARS AGO -Time 15,000 population of North America begins Plant and Animal Domestication Upper Paleolithic Cultures Time I ι 1 I 8,000 5,000 3,000 2,500 Jericho First invention of writing MIDDLE STONE AGE in Sumer 3200-3000 (Mesolithic) (in Europe 2900-2700) NEW STONE AGE (Neolithic) BRONZE AGE PYRAMIDS 2000 1900 Geothermal use begins Natural gas use Uranium fission Solar power use? Nuclear fusion? Fig. 1-1 Graphic representation showing the vast difference in time between our rapid use of fossil fuels (bottom segment) and their early formation. 4
The list of books you might like
