increases total production through positive feedback and ... the real issue is whether they can do so indefinitely in a competitive environment .... bined system of humanity and nature, sunlight and fuels ..... means that it uses more input than is economically com petitive ...... directly or indirectly on subsistence cultivation as the.
MAXIMUM POWER The Ideas and Applications of H. T. Odum
Charles A.S. Hall, Editor
UNIVERSITY PRESS OF
COLORADO
© 1995 by the University Press of Colorado Published by the University Press of Colorado P. O. Box 849 Niwot,Colorado 80544 All rights reserved. Printed in the United States of America. The University Press of Colorado is a cooperative publishing enterprise supported, in part, by Adams State College, Colorado State University, Fort Lewis College, Mesa State College,Metropolitan State College of Denver,University of Colorado, University of Northern Colorado, University of Southern Colorado, and Western State College of Colorado.
Library of Congress Cataloging-in-Publication Data Hall,Charles AS.,1943Maximum Power: the ideas and applications of H. T. Odum ; Charles AS. Hall,editor p.
cm.
Includes bibliographical references and index. ISBN 0-87081-362-5 1. Environmental policy. resources.
2. Environmental sciences.
4. Human ecology.
6. Environmentalists-United States-Biography. T.,1924-
.
GE170.M39
1995
3. Power
5. Odum, Howard T.,1924I. Odum,Howard
II . Hall,Charles AS. 94-39093
363.7-dc20
CIP
This book was set in ITC New Baskerville and ITC Eras. The paper used in this publication meets the minimum requirements of the Amer ican National Standard for Information Sciences -Permanence of Paper for Printed Library Materials. ANSI Z39.48-1948 00
10
9
8
7
6
5
4
3
2
1
Chapter 22 REDISCOVERY OF THE WORLD: DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS M. T. Brown, H. T. S. J.
Odum, R. C. Murphy R. A. Christianson,
Doherty, T. R. McClanahan, and S. E. Tennenbaum
Introduction
The studies used techniques of emergyl analysis to eval uate both traditional economic variables and ecologic sys
Among the most important problems facing humanity
tems (Odum 1978; Odum 1988). This method evaluates
today are the sound management of natural resources
on a common basis the main driving energies of the econ
and development of procedures for the integrated study
omy and the requirements and contributions of individual
of human and natural processes. Increasingly, there is a need to understand both human and natural domains, each in the context of the other, and to develop manage ment strategies that acknowledge and promote the vital interconnections between the two. Neither the discipline of economics nor ecology alone adequately addresses the problems world society currently faces. Questions of opti mizing resource use, managing equitable international trade, overexploitation of resources, loss of biotic diver sity, or global climate change cannot be solved by focusing on isolated aspects of a larger problem. A wider view is necessary: one that combines the systems of humanity and nature and that does not treat the affairs of humans and the productive processes of the biosphere as distinct enti ties, one having domain over the other. A new paradigm for such an analysis is emerging. Just as the separate and distinct economies of individual nations are becoming increasingly interwoven into a worldwide economic sys tem, it is becoming quite apparent that economic well being and ecologic stability depend upon developing an interface between ecology and economics.
Background In 1984, The Cousteau Society, who initiated and sup ported this research, embarked on a series of expeditions entitled "Rediscovery of the World." In conjunction with this continuing worldwide expedition,the authors investi gated pressing resource questions in four regions visited
development projects. Included are economic goods and services,fuels,and the fluxes of renewable energies as well as environmental changes that occur, such as the loss of terrestrial production. Emergy analysis allows comparison and incorporation of environmental costs and benefits with variables of traditional economic costs and benefits to provide a more comprehensive perspective for policy decisions (Gilliland 1975; Odum 1978). The objective of The Cousteau Society is to educate and communicate on a global scale so as to protect and improve the quality of life for current and future generations. These studies were undertaken within that context: to educate and enlighten and to provide perspectives for public policy decisions that will increase the chances of a sustainable and productive economy for the coming generations.
Public Policy: The Interface of Ecology and Economics The interface of ecology and economics is most often found in the marketplace. Resources are exploited and sold, and in the process, the environment sustains some transformations. Questions of how best to manage a nation's resources, how to develop them and to extract them, and whether they should be exported in exchange for other needed resources are public policy questions. Until very recently, public policy was most often deter mined almost wholly within an economic framework, most commonly within the limited context of market transformations. Yet economic considerations often do not reflect ecologic realities, societal needs, environmen
by the Cousteau expedition teams: the Amazon Basin, the
tal impacts, or sustainability of natural resources, because
Mexican Sea of Cortez,Papua New Guinea,and Thailand.
these things are generally outside the realm of individual
In each region or country, an overall analysis of its econ
human preferences or the ability of markets to provide
omy was undertaken, followed by the analysis of one or
adequate
more questions of important public policy concern.
Lierop 1987; Hall 1992).
216
information
(Jansson
1984;
Braat and van
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS A new public policy value system is required-one that can recognize the differences between short-term individ ual human preference and long-term macroscopic eco nomic well-being and that can quantitatively determine value at the macroscopic scale of society and environ ment. The emergy analysis methodology that we used to study these four regions first developed a systems overview of the region and the problems of interfacing parts of the environment with human economies. Then, main driving energies and processes of the economy were evaluated quantitatively in units of emergy. Finally, recommenda tions were made for public policy options based on the principle that the alternative that maximizes emergy is the preferred choice. Theory suggests (Odum 1971; Odum 1983a; Odum 1983b; Odum and Odum 1983) that economies of nature and humans organize so as to develop the maximum emergy possible and that in so doing they prevail and are sustained over alternatives. The theoretical basis is found in the Maximum Power Principle (Lotka 1922a; Lotka 1922b; Lotka 1945) . To maximize power, an economy develops an organization of useful processes that increases total production through positive feedback and by overcoming limiting factors. Economies, in the long run, cannot prevail in competition with others if emergy is wasted in nonproductive processes; yet in the short run, one can observe apparent contradictions. However, because observations of any system are time dependent, the real issue is not that processes exist that seem to "waste" emergy (i.e., do not reinforce productive pro cesses) and thus violate the maximum power principle; the real issue is whether they can do so indefin itely in a competitive environment where selective processes are geared to eliminate them. This view is in contradiction to some economic theories that suggest any expenditure of money and resources leads to economic vitality, even if it is for unnecessary products or services. Many scientists are used to thinking of systems as orga nizations of processes that are sustained by their driving energies and resources and that competition and com petitive exclusion are the means by which systems self organize and develop sustainable patterns. Yet few believe that the criterion for survival, or sustainability, is maxi mum emergy or that competition and competitive exclu sion are selective processes that operate to maximize emergy. Other criteria for survival that have been sug gested include minimum cost, minimum risk, maximum stability, maximum efficiency, maximum production, least work, and maximum diversity, among others. The viewpoint used in these studies is that economies, and processes within economies, organize and operate so as to increase real wealth and prevail according to the maxi mum emergy principle and that a measure of real wealth is emergy.
2 17
Emergy, Wealth, and Economic Vitality Emergy is a quantitative measure of the resources required to develop a product (whether a mineral resource that results from biogeologic processes, a bio logic resource such as wood, or an economic product that results from industrial processes) and expresses the required resources in units of one type of energy (usually solar) . We suggest that evaluations using emergy may help to clarify policy options because the use of emergy as a measure of value overcomes four important limitations of previous attempts to quantify environmental impacts, development cost/benefits, and alternative technologies. These limitations are as follows: (1) Mixing units of mea sure like weight, volume, heat capacity, or economic mar ket price cannot lead to comparative analysis. The relative contribution to a nation's economic vitality derived from fossil fuels (measured in barrels) , sunlight (measured in ergs), and phosphorus in fertilizers (measured in kilo grams) is difficult to determine. (2) Evaluations that use the heat value of resources for quantification assume that the only value of a resource is the heat that is derived from its combustion. In this way, for example, human services are evaluated as the calories expended doing work and, when compared to other inputs to a given process, are sev eral orders of magnitude smaller and often considered irrelevant. (3) Unmonied resources and processes (Le., those outside the monied economy) are often considered externalities and not quantified. Most processes and all economies are driven by a combination of renewable and nonrenewable energy. Renewable energies (sunlight, rain, winds, tides, and so forth) are outside the monied econ omy and therefore are generally not accounted for in eco nomic evaluations. Yet they are absolutely necessary in all economies and make up a large portion of most products. Economic vitality depends on the successful use of avail able resources, both renewable and nonrenewable (fuels, mineral resources, and the goods derived from them) ; thus evaluations that leave out renewable emergies because they are externalities consistently "undervalue" the total production in economies and environmental processes. (4) Price determines value. The price of a prod uct or service reflects human preferences often called "willingness to pay." It can also reflect the amount of human services "embodied" in a product. A valuing sys tem based on human preference assigns either relatively arbitrary values or no value to necessary resources or envi ronmental services. Emergy is a measure of the real wealth of an economy (Odum 1984; Odum and Arding 1991) . Because wealth is ultimately tied to resources, it is necessary to express wealth in units that reflect the resource base. Trained as we are, that price reflects value, we often believe that money is the measure of wealth and that price determines value. Price suggests what humans are willing to pay for something; but value to the public is determined by the
M. T. BROWN ET AL.
218 effect a resource has in stimulating an economy. For example, a gallon of gasoline will power a car the same distance no matter what its price; thus its value to the driver is the number of miles (work) that can be driven. Its price reflects the scarcity of gasoline and how impor tant it is to do the work. Price is often inverse to a resource's contribution to an economy. When a resource is plentiful, its price is low, yet it contributes much to the economy. When a resource is scarce, its total contribution to the economy is small, yet its price is high. Emergy is an estimate of the equivalence when one resource is substituted for another. Sunlight and fossil fuels are very different energies, and when their heat val ues are used, the difference is not elucidated. A joule of sunlight is not equivalent to ajoule of fossil fuel in any sys tem other than a heat engine. In the realm of the com bined system of humanity and nature, sunlight and fuels are not equally substitutable joule for joule. However, when a given amount of fuel energy is expressed as solar emergy, its equivalence to sunlight energy is defined. Because emergy is a measure of the work that goes into a product expressed in units of one type of energy (sun light) , it is also a measure of what the product should con tribute in useful work in relation to sunlight. We recognize the difficulty that these concepts present because they use new terminology and a different mea sure of value from those in common usage. However, the concept of value and national wealth stemming from resources is not new but is as old as economics itself. The history of economic thought is replete with considerable discussion and analysis of national wealth as measured by resources and by attempts to measure value as it stems from resource use (see Whittaker 1940; Hutchison 1953; Heimann 1959; Ingram 1967; Blaug 1968) . Only recently has economic theory been dominated by the determina tion of value based on price and national wealth measured by currency. During times of resource scarcity, economic values were related most often to resources (land, labor, or energy) and resource use; but during times of resource abundance, economic values were related most often to currency and price. The failing of previous theories of resource-based value, and most current theories as well, has been that they did not account for different types of energy but assumed that the heat value of energy was a common denominator by which quantification and comparisons could be made (Slesser 1978; Slesser 1987) . We believe this to be incorrect. All energy types are not equivalent in their ability to do work; and without accounting for the differences in what has been termed the quality of differ ent types of energy, erroneous conclusions can result. Use of emergy to represent all the contributions to any given product or process accounts for differences in resource quality and expresses different resources in equivalent capacity to do work.
Plan of Study The study presented in this chapter summarizes analyses of four regions under development pressure (Figure 22.1), and includes results from four larger reports (Odum et al. 1986; Brown et al. 1989; Brown et al. 1991; McClanahan and Brown 1991) . These studies address some of the following important policy issues: 1.
In the Amazon, questions concern sustainable agro forestry and deforestation, energy development, and international trade;
2.
In the Mexican Sea of Cortez (Gulf of California) , questions concern the relationships between Colo rado River discharge and marine productivity, exploi tation of marine fisheries, and international trade;
3.
In Papua New Guinea, questions concern renewable resource exploitation, unequal international trade, potential loss of cultural values, and quality of life;
4.
In Thailand, questions concern alternative proposals for the damming of the Mekong River for its hydro electric potential.
Everything is part of a system, and systems are com posed of interrelated units. Each system was studied as a whole in order to understand how the functions and values of individual units fit together. In each regional analysis, we started with the whole economy in overview. This "top down" approach facilitates a better understanding of sub systems and their public policy issues. Decisions regarding the exploitation of natural resources almost invariably require the integration of both economic and ecologic concerns. All too often policy decisions on the local level are made without sufficient information concerning the implications to the next larger system level. The reverse is also true; decisions made at the regional or national level have serious impacts on local economies and resource sys tems. The hierarchical systems approach presented in these studies lends insight and allows for the public policy decision process to integrate both the economic and eco logic implications of management alternatives.
Methods Emergy analysis provides an overview of the resource base interactions of systems of humanity and nature (Odum 1988) . This is accomplished by first gathering relevant information and statistics about the complete system and diagramming the system using the energy language sym bols illustrated in Figure 22.2. Next, total energy of each input to the system is calculated; then aggregate diagrams are created emphasizing the subsystems of interest. Finally, the emergy of the subsystems (the resource base in terms of equivalent solar input) is calculated so that com parisons can be made and indices can be calculated to provide perspectives on trends and policy.
219
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
Figure 22.1
Four regions of world under development pressure: Sea of Cortez, Amazon Basin, T hailand, and Papua New Guinea.
There are several terms and concepts that are used in this chapter that are not in common usage or that may be unfamiliar to the reader. They are defined next.
Emergy (spelled with an "m"). Emergy includes the energy of one type directly and indirectly used in pro duction of a resource, product, or service. Solar emergy in a resource, product, or service is the sum of the solar ener gies required. Emergy includes both fossil fuels energies and environmental energies (like sunlight, rain, and tides) that are necessary inputs to most processes of energy transformation. Thus the emergy of a fish sold at market includes the prorated share of emergy spent for goods and services necessary to run and maintain the fish ing vessel, the emergy of the fuel that was burned, the emergy value of the goods and services consumed by the fishermen, and all the emergy from direct sunlight and tidal action that was necessary to provide essential ecologi cal support for the fish prior to its being caught. Emergy can be conceptualized as energy memory (Scienceman 1987; Scienceman 1989) in that it is a measure of all the energy previously required to produce a given product or process. The term emergy differs from embodied energy as defined by other schools of thought in that it always includes all energies with quality corrections. For exam ple, environmental inputs and labor are omitted by some
(International Federation of Institutes of Advanced Study 1974; Slesser 1978) . Energies are added without using transformities by others (Hall et al. 1986) ; and energies are assigned by input-output data (usually money flows) with no quality correction (Hannon et al. 1976; Her endeen et al. 1975; and Costanza 1978) . The numbers derived are different from emergy results. Attempts to evaluate environmental and economic products or services in units of energy must recognize that all forms of energy do not accomplish equivalent amounts of work (Odum 1976; Odum 1978; Odum 1988; Odum and Odum 1983) . To express the energy value of sunlight and fuel in joules of heat and then to suggest that each joule is equal in its ability to support work is not accurate. The "form" or "quality" of each type of energy is different and capable of supporting different types of work per unit of energy. To overcome this shortcoming, a measure of work potential based on solar energy equivalence can be used to describe all types of energy as solar emergy. Solar emergy whose units are solar emjoules (sej) are used in this chapter.
Transformity. Transformity is the energy of one type required to generate one unit of another type. It is a ratio whose units are solar emjoules per joule (abbreviated sej/J [Odum 1986; Odum 1988]) .
M. T. BROWN ET AL.
220
0-
OUTSIDE ENERGY SOURCE-delivers energy flow from outside the system.
Item HEAT SINK-drains out degraded energy
---2--:
DQ
-Q Figure 22.2
sej/g
1 1 ,496
Geothermal heat energy
6,055
ENERGY STORAGE TANK-stores and
Geothermal convection
1 1 ,000
delivers energy flow.
Rain, physical energy
1 0,490
Rain, chemical potential
1 8,200
-
+
Solar energy Wind, kinetic energy
--
-0
Transformity sej/J
Primary emergy sources-renewable after its use in work.
�
Table 22. 1 Partial listing of solar transformities used in studies of wor ld regions
ENERGY INTERACTION-requires two
Tidal energy
1 6,840
or more kinds of energy to produce high-
Ocean currents
27,870
Wave energy
30,550
Earth cycle energy
25,51 4
Rivers, physical energy
27,870
Rivers, chemical potential
48,460
quality energy flow.
ENERGY-MONEY TRANSACTIONmoney flows in exchange for energy.
Hurricane (total energy) GENERAL PURPOSE BOX-for any subunit needed, is labeled to indicate use.
PRODUCER UNIT -converts and concentrates solar energy, self-maintaining; details may be shown inside.
CONSUMER UNIT-uses high-quality energy, self-maintaining; details may be shown inside.
Energy language sym bols.
The solar transformity of an object or resource is the equivalent solar energy that would be required to gener ate a unit of that object or resource efficiently and rapidly. It is the ratio of the total amount of solar energy required to create it (solar emergy) to the energy of the resource. It is obtained by dividing the total solar emergy of the system that "creates" the resource by the energy in the resource output. As an example, the transformity of a fish would be calculated by dividing the tidal and solar energy required to support the environmental system that "produces" the fish by the energy of the fish (measured as caloric value) . In practice, once a transformity for a product has been calculated, the solar emergy in a like product is obtained by multiplying its energy (joules) by its solar transformity (sejlJ ) , converting it to solar emergy (sej ) . Given in Table 22.1 is a list of transformities for many types of energy and commodities derived from previous studies.
1 ,673
Hurricane (kinetic energy)
55,763
Topsoil formation energy
73,750
Organic matter (rivers)
1 9,000
Net geological uplift (physical energy)
3.22 E+I0
Primary emergy sources-nonrrmewable Fuelwood production
18,700
Rain forest (in situ)
38,360
3.79 E+08
Harvested rain forest wood
40,250
3.98 E+08
Rain forest wood (chipped, trans.)
40,910
4.04 E+08
Pulp product
3.90 E+09
Topsoil erosion
73,750
Sediments in river
73,750
Lignite
37,000
Coal
40,000
Natural gas
48,000
Crude oil
54,000
Liquid motor fuel
66,000
Electricity
2.0 E+09
200,000
Corn, primitive
58,1 00
8.55 E+08
Rice, low energy
24,000
4.50 E+08
Rice, high energy
44,000
8.30 E+08
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS Table 2 2 . J (Cont'd) Partial listing of solar transformities used in studies of world regions Transformity sej/J
Item
sej/g
Nitrogen fertilizer (NH3)
1 .59 E+06
3.45 E+09
Nitrogen (N)
1 . 70 E+06
4.21 E+09
as
NH3
Fisheries
2.0 E6
Primary emergy sources-nonnmewahle
Livestock, poultry
2.0 E6
Potassium fertilizer (potash)
7.02 E+06
2 .96 E+09
Phosphorus (phosphate)
5.99 E+07
6.88 E+09
Paper, cardboard
2.15 E+05
Bauxite
1.27 E+07
1 .00 E+09
Pesticides (mix)
9.78 E+05
1 .48 E+10
Phosphate rock (in situ)
3.76 E+07
1.31 E+10
Iron ore
6.00 E+07
1 .00 E+09
Cement
7.48 E+08
Concrete
9.26 E+07
Refined steel
5.15 E+07
4.65 E+09
Iron and steel end product
1 .39 E+08
1 .25 E+10
Copper and zinc alloys
6.80 E+1 0
Silver
3.00 E+1 4
Gold
4.40 E+14
Sources: Transfonnities are from the following: Odum et al. 1983, Odum
et al. 1987a, McClanahan and Brown 1991 , Christianson 1984, dated in Arding and Brown 1991.
as
up
Energy Diagrams of Regions and Subsystems Energy systems diagrams were drawn using symbols and language conventions provided in a number of texts (Odum 1971; Odum 1983a; Odum and Odum 1983) . Some explanations of the main symbols are given in Fig ure 22.2. Mter a boundary of the system was indicated with a rectangular frame, outside influences were shown with source symbols (circles) arranged from left to right in order of increasing transformity. Within the frame, main components such as producers, consumers, storages, and interactions were shown, again arranging symbols from left to right according to transformity. Then, pathways were connected between symbols. The way the pathways were joined to each other and to the symbols indicated the mathematical relationships such as adding, multiplying, and integrating. The energy diagram provided a visual overview of the system. The diagram represented hierar chy from numerous smaller items on the left converging to fewer, larger territoried items on the right. Flows of money were included as dashed lines and related to other flows by prices. Mter a diagram was produced, a simpler version was developed by aggregating (combining) some units that were shown separately in the first inventory.
22 1
Emergy Analysis Mter the initial energy diagram of a region, subsystem, or process was drawn, it was simplified by aggregation to show only the principal inputs and flows, pathways, and storages. Energy flow data were acquired from national statistical abstracts, scientific literature, and in some cases through direct observation and personal communication in the respective countries. The sources of energy flow data and the calculations for each analysis are available in the reports cited for each study presented in each section. Once energy flow data were obtained for each pathway, an emergy analysis table for calculating solar emergy was constructed for each subsystem or process that was ana lyzed. In the first column, the flow is listed by name. The second column provides the energy of the flow, whatever the type of energy. In the third column, transformities are listed as derived from the collective work of numerous other studies (Odum and Odum 1983; Odum et al. 1987a; Odum et al. 1987b) . Finally, the energy values in the sec ond column are multiplied by the transformities in the third column to obtain the solar emergy equivalent in the fourth column. We sometimes generate a fifth column that expresses the solar emergy equivalent in the fourth column as macroeconomic dollars, based on the ratio of total emergy flow in the economy to dollar flow in the economy (GNP) . Macroeconomic dollars in the third col umn are calculated by dividing solar emergy in the fourth column by the ratio of total emergy:GNP $ for the country within which the analysis was performed.
Computer Simulation We simulated on microcomputer "macroscopic minimod els" (Odum 1988) of several of the issues considered here in order to develop perspective on temporal changes and to gain added insight for policy suggestions. Where simu lation was conducted, systems diagrams were drawn con taining the essence of the system in question, and then simulation programs were written directly from the dia grams. The mathematical relationships were readily implied by the diagram because each pathway has a char acteristic mathematical term that goes with each kind of symbol-pathway pattern. Thus a set of differential equa tions may be written by inspection, one equation for each unit in the diagram that has storage properties. From the equations, microcomputer simulation programs were writ ten in FORTRAN or BASIC. To calibrate the coefficients of the model's equations, values of storages and flows were written on the energy diagram pathways where it was easy to compare and check numbers. For example, the flow of money in and out of a system could be set equal, thus cali brating at steady state to simplify calculations of coeffi cients. Mter a number was substituted for each flow and storage in a mathematical term in an equation, the equa tion was solved for the coefficient value. Then, the coeffi cients were entered in the computer program. Graphs were generated by the computer showing the nature of
222
growth, leveling, oscillation, and so forth that the set of assumed relationships and values generated.
Emergy Criteria for Economic Evaluation Several emergy-based indices that we have found useful for evaluation of resource questions are net emergy yield ratio, the emergy investment ratio, and ratio of emergy to money. For example, fuels may be evaluated with the net emergy yield ratio, which is the ratio of yield to the inputs supplied by the monied economy. Yield ratios calculated in this manner are an indication of the contribution of a resource to an economy. If a source of fuel has a lower net emergy yield ratio when compared to another fuel, it means that it uses more input than is economically com petitive. When the net yield ratio is less than 1.0, it is con sidered a "consumptive transformation" of emergy. While not yielding net emergy (i.e., yielding more emergy than invested), these processes are often important because they produce resources of importance. For example, agri cultural products mostly do not yield net emergy, yet the transformation is necessary and yields a product (food) that is of importance. Proposed energy sources with ratios greater than 1 but less than ratios typical of primary energy sources are considered secondary sources. Despite having net emergy yield ratios greater than 1, these types of sources cannot contribute sufficient net emergy to drive a high-energy, growth-oriented economy. Proposed energy sources with ratios equal to or higher than current primary sources like oil or natural gas may be considered primary sources. The emergy investment ratio is the ratio of the inputs from the economy to the free inputs from environmental resources. The ratio is useful for determining the relative contribution of free inputs. For a process to be competi tive, it must have as much free input as competitors. The ratio also measures environmental loading, or the degree to which human economies are "loaded"2 on the environ ment. A high ratio means that the environment supports higher levels of economic activity than other regions or processes that have lower ratios. By summing the main emergy inputs of a country and dividing by the gross national product (GNP), an emergy/dollar ratio is derived for that country (expressed as sej/GNP$). This can be used to estimate the emergy that supports and goes with paid services by multiplying dollar flows by the ratio emergy/GNP dollars. There are two values of emergy that are associated with any pur chased input to a process. The first is the emergy inherent in the resource or commodity; and the second is the emergy that is associated with its delivery (Le., the emergy in the services used to process, transport, and market it). The total emergy of a resource or commodity is the sum of the two. The first emergy is derived from quantitative evaluation of the resources and energy flows that support the productive processes that produce the resource or
M. T. BROWN ET AL.
commodity. The second emergy is estimated by multiply ing its dollar price by the ratio emergy/GNP dollars. The ratio of emergy per capita is a useful measure of total emergy contributions to a population's existence. Rural populations receive more emergy directly from the envi ronment without money payment than do urban popula tions. In this case, money does not measure their relative standards of living. Therefore, the total emergy flow sup porting humans and their local economies may be a more comprehensive measure of standard of living than dollar income alone.
Policy Criteria Emergy analysis may be used for choosing between alter native plans and policies. Alternatives with higher emergy inputs to an economy increase its vitality and competitive position by contributing more wealth. We propose that, in the trial-and-error process of human decisions, the pat tern that generates more emergy will tend to prevail and be copied. Recommendations for future plans and poli cies that are likely to be successful are those that go in the natural direction-toward maximum emergy production. In this study, policy recommendations are based on crite ria that will result in the highest emergy inputs into an economy and that are sustainable in the long run. These criteria and alternatives for the most part result in long term policy decisions that often run counter to short-term economic wisdom. Criteria for maximum power include not only increasing the rate of energy inflow but also effi cient use of the power supplied. In this context, the most successful configuration, or organization, of a system is not the one that disperses its energy the fastest but the one in which the most useful work can be done over long time periods.
Results and Discussion Our effort to develop conceptual overview models of the world begins with the Amazon Basin and is followed by the Sea of Cortez, Papua New Guinea, and Thailand, respectively. Papua New Guinea and Thailand were first studied as a whole, after which questions of subsystem public policy were addressed.
The Amazon Basin The Amazon Basin is the largest tropical river system and largest stand of tropical moist and rain forests in the world. Brazil, with a high rate of population growth and with the largest international debt, is placing great demands on the Amazon region to help alleviate these problems. Roads are being constructed throughout the basin to open lands for development and resettlement of people. Enormous hydroelectric projects and mining operations are converting large tracts of land to lakes and other uses. Conversion of forest land to pasture, to other
223
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
Figure 22.3
Energy diagram of the Amazon Basin showing forest areas, hydroelectric dams, rural land uses, and urban lands. Letters in symbols are the following: ET evapotranspiration; L land; W wood; C cattle; A assets; P price; IR interest rate; es environmental services. =
=
=
=
=
=
=
=
forms of agriculture, and to forestry plantations is increas ing. At the same time, appreciation of the Amazon system is mounting as a world community becomes concerned about global climate, habitat loss, and species extinction. Given in Figure 22.3 is a summary diagram of the basin. Table 22.2 summarizes inflowing energy sources and out flowing exports. Among the many development projects Cousteau teams observed during their 18 mo expedition in the Amazon were the forest plantation and associated pulp mill on the Jari River and the hydroelectric dam on the Tucantine River near Tucurui. These seemed particularly important because they were being considered as pilot projects, which, if successful, would be replicated else where in the Amazon Basin. Our studies focused on these projects (Odum et al. 1986). Jari Florestal e Agropecuaria. In the mid-1950s, U.S. shipping magnate Daniel Ludwig financed and developed a system of tropical forest plantations and an associated pulp mill on the Jari River in northeastern Brazil. This became the largest individually owned tract of land and the world's largest tree farm, Jari Florestal e Agropecuaria, commonly referred to as Jari. The 16,000 km2 tract of land was divided into a forest reserve and a plantation. In
addition, a worker community, power plant, and pulp mill were constructed. Price for the 1967 purchase of the land was $3 million, or about $1.90/ha. The pulp mill and wood-fired electric generator were constructed in Japan and towed by barge across three oceans and up the Ama zon to Jari. The plantation grew Melina Gmelina arborae, a pine (Pinus caribaea var. hondurensis) and a gum (EucaLyp tus sp.). Estimates of the cost of the project were approaching $1 billion in the early 1980s when it was sold in 1982 by Ludwig to a Brazilian consortium of twenty seven firms for $280 million, just over one-fourth of the original investment. The basic questions posed regardingJari were whether the project, as implemented in 1983, was ecologically and economically sustainable and, if not, were there any sus tainable alternatives. This study began with the creation of a conceptual, energy systems diagram for Jari, presented in Figure 22.4. Whereas the plantations supply fiber for pulping, the fuel for the power plant came from clear-cut ting the native forest as plantations were created. The depletion of soils represented an input of emergy from within the system. Inputs that were not locally derived included liquid fuels for transport and supplementation of the wood fuel in boilers, fertilizer, chemicals used in
224
M. T. BROWN ET AL.
Table 22.2 Inflowing energy sources and outflowing energy exports for the Amazon Basin
Item
Units/yr
Transformity Solar Emergy sej/unit E21 sej/yr
Renewable Resources (R) Sunlight
5.86 E+22J
Rain, physical energy
5.73 E+19J
58.6
Solar energy
6.70 E+19J
Wind, physical energy
7.10 E+14J
1 ,496
67.0 1.1
5.44 E+15J
10,490
57.1
18,200
791.7
18,200
1,676.2
16,840
0.1
Wave energy
3.52 E+16J
30,550
1 .1
2.85 E+19J
27,870
794.4
Rivers, chemical potential 2.72 E+ 19 J
48,460
1 ,318.1
Sediment load in rivers
73,750
22.9
Indigenous Renewable Energy Hydroelectricity
1 .65 E+ 1 4J
20,000
0.0
Forest extraction
1 .80 E+ 19 J
40,248
720.0
66,000
1 3.0
Indigenous Nonrenewable Sources (N)
Imports and Outside Sources Fuels
1 .67 E+17 J
66,000
11.0
Services
5.14 E+09 $
3.80 E+1 2
19.5
1 .90 E+l l g
1.00 E+09
0.2
Exports Iron ore
Units/yr
4.35 E+16J
9.21 E+ 1 9J
1.97 E+17J
Item
Rain, chemical potential energy
4.14 E+15J
Fuel consumed
Solar Transformity Emergy E1 8 sej/yr sej/unit
Rain, physical energy
Tidal energy
3 . 1 1 E+ 17 J
Jari plantation and pulp mill emergy flows
10,490
Rain, chemical potential
Rivers, physical energy
Table 22.3
Bauxite
1 .30 E+1 2 g
1 .00 E+09
1 .3
Lumber
7.16 E+16J
40,250
2.9
Paper
3.60 E+15J
2.15 E+05
0.8
SouTce: Odum et al. 1986.
the pulping process (sulfur/limestone), some equipment replacements, food for employees, as well as other goods and services for the plant'S operation. Included in theJari system were the operation of roads, health facilities, hous ing, and other necessities for people working within the system. Energy and emergy of input and output flows are provided in Table 22.3. For comparison with other resources and energy sys tems, two emergy ratios were calculated: (1) investment ratio and (2) emergy yield ratios (see Table 22.4). Three different investment ratios are given forJari and the econ omies of Brazil and the United States in Table 22.4. The differences are related to different treatments of the depletion of internal storages (in the case ofJari, the stor age depletion is rain forest wood and soils). The first ratio does not include storage depletion. The second ratio includes storage depletion by summing with natural emergy input to the process. And the third ratio includes it as a nonrenewable input and sums storage depletion with purchased outside investments. Also presented in Table 22.4 are two net emergy yield ratios. The yield ratios
Tidal energy
5.02 E+14J
16,840
8.5
Rivers, physical energy
2.72 E+15J
27,870
75.6
Rivers, chemical potential
3.93 E+12J
48,460
0.2
Liquid fuels
8.73 E+14J
66,000
55.2
Soil loss-fertilizer required
1 .21 E14J
1 .59 E+6
193.0
Goods-salt
2.50 E+07 kg
1 . 1 2 E+12
28.0
Goods-sulfur
3.70 E+06 kg 9.91 E+l l
3.7
Goods-carbonate
2.20 E+07 kg
Native fuelwood consumed Lumber export
3.42 E+1 2
75.2
6.00 E+05 T
4.00 E+14
240.0
1 . 1 0 E+04 T
4.00 E+14
4.4
Pulp product
2.15 E+05 T
3.90 E+15
838.5
Exports (products)
8.16 E+07 $
6.7 E+12
546.7
Imports (goods and services)
4.60 E+07 $
3.8 E+12
174.8
SOUTce: After Odum et al. 1986.
are calculated for the yield when emergy of storage deple tion is not included (2.50/1) as well as for yield when emergy of storage depletion is included (1.09/1). For estry does not have to be a net emergy to be economic and useful. To be economic and competitive, the invest ment ratio needs to be less than that of the rest of the Bra zilian economy. Table 2 2 . 4 Emergy analysis ratios for Jari and comparisons with the economies of Brazil and the United States
Jari
Brazil
USAl
0.42
0.17
1.92
Outside/natural energy + storage depletion
0.27 0.10
0.37
Outside + storage depletion/natural energy
0.97
0.38
6.09
Yield/outside investment
2.50
8.31
3.68
Yield/outside investment + storage depletion
1.09
3.62
1.16
Item Investment Rntios
Outside/ natural energy
Emergy Yield Rntios
SOUTce: After Odum et al. 1986. l Ratios were derived from Arding and Brown 1991.
The comparisons in Table 22.4 suggest that (1) Jari is not particularly competitive (its investment ratio is higher than that characteristic of the Brazilian economy) and (2)
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
Figure 22.4
Overview
of Jari
plantation and pulp mill.
N
=
nutrients; R
225
=
rocks, C,
8, T
=
cut
burn, and transport; W
=
waste; ET = evapotranspiration.
Jari's net yield ratios are relatively low, reflecting the large requirements for purchased energy to harvest and process the forestry products. A second question considered was whether there might be sustainable alternatives to the 1983 Jari project. Energy systems principles were applied to theJari planta tion in order to determine alternative land-use strategies that would be more economically viable and ecologically sustainable. Gross features of production, consumption, nutrient recycling, biomass, diversity, reseeding and suc cession, rotation, and economic utilization were incorpo rated in a series of simulation models of the natural tropical forest system in general. From these simulations it was concluded that a land-rotation system may maxi mize productivity so that forest and economic compo nents survive. One of the land-rotation simulation models developed specifically for Jari is shown in Figure 22.5. Various sce narios were tested including varying the use of fertilizer and intensities or rates of conversion from native land to plantation. Figure 22.6 shows simulation results of the model with inputs of fertilizer use and five different native forest conversion rates. With the use of fertilizer
and at low levels of forest conversion (2,000 ha/yr), the forest (5) is barely impacted, and the return on invest ment (I) is so low as to be outside the monied economy. At 9,000 halyr, there is a stable rate of return on the investment in 20 yr, but by 75 yr, native forest biomass lev els off at about 70%. At higher rates of forest conversion, long-term stability is questionable, and the rate of return on investment declines. The optimal intensity of develop ment predicted by the model was 7,000 halyr, with the peak rate of return at the fiftieth year, and the optimal ratio of developed land to native land use was 0.23, which corresponds to 18.75% of the total land area in planta tions at one time (the remaining 4.25% is consumed by infrastructure). Under these conditions, the average pro duction would be 1,220,000 t of pulpwood per yr. Inter nal rate of dollar return on dollar investment would be about 5% above inflation at 50 yr. According to model behavior, development beyond a total of 1.5 E5 ha atJari would result in declining marginal returns. Without fertilizers, model simulations suggest, pulp wood could not be produced without degradation of the nutrient status of soils-which is to say the nutrient status is not sustainable. This is not to say that the land could not
226
Figure 22.5
M. T. BROWN ET AL.
Land-rotation model. showing native forest. plantation, and land areas. Imported goods and services control the rates at which lands are shifted from native land to plantation land and maintenance on plantation forests.
be used, at a relatively low density, on a rotational cycle for agriculture. Our model showed that the optimal ratio of developed land to total land without fertilizer was about 0.775/1, or about 7.75% land developed. This ratio is sup ported by data from the literature (Goodland 1980; Carter and Snedaker 1969) on native land use, where sus tainable population density is related to land area under active cultivation. Their data gave a ratio of developed land to total land of 7.1%. A final concern was expressed to the government of Brazil regarding the long-term consequences of such projects. Should such a massive project fail, Brazil would be left with a gigantic scar on the landscape because of the delay in reseeding over long distances. Land-use strategies involving relatively small clear-cut areas interspersed with natural reserves to facilitate the natural processes of reseeding and mature forest development would seem to make good ecological sense and ensure quicker recovery. A hydroelectric dam near Tucurui. In order to develop the rich iron ore deposits at nearby Car.yas, a hydroelectric plant was developed on the Tucantine River, a major tributary of the lower Amazon River. At completion, the facility was the fourth largest hydroelec tric plant, in generating capacity, in the world. Interest remains high with regard to the Amazon's hydroelectric
potential, estimated at 100,000,000 kW, and numerous plans exist for future development. It is our belief that the traditional method of evaluating a dam's efficiency does not involve a complete energy accounting. Because this dam, likeJari, was being considered as the first in a series of comparable developments, we felt it would be worthwhile to undertake a more complete net emergy analysis. System boundaries include the "powershed" of the dam because the overall effects of the dam are felt throughout that entire area. This area is approximately 2.3 E5 km2 and includes the delta of the Tucantine River where it meets the Amazon. A conceptual model of the Tucurui Dam powershed is presented in Figure 22.7, with flows and storages shown in Table 22.5. The economic cost of the dam, estimated at U.S. $4.6 billion, was converted to emergy units using the 1982 emergy:money ratio for Bra zil of 6.7 E12 sej/$. The dollar costs of goods, services, and fuels were likewise converted to emergy according to their respective transformities. Other costs include the loss of forest production (even though some of the forest wood was harvested), soil and sediments, downstream effects on forest and fisheries, and relocation of indige nous people. Benefits include the electricity produced by the dam and aquatic production.
227
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
2,000 hB/yr
1 00
9,000 hB/yr
8
�
�
>-
c:
«I ::l
0
N
o
Time (yr)
10
I
M
c:
M
«I ::l
o
8
�
-
"2 N
t-2
1 00
Time (yr)
, 6,000 h B / y r
23,000 hB/yr
�
�
�------ A2
c:
M A2 S
«I ::l
M
0
N
Time ( y r)
1 00
100
Time ( y r)
30,000 h B/yr
STORAGES 8
= N a tlv a For •• t Bloma ••
M
= Money
N
=
,...
� .�
Nutrient.
c:
(II ::>
A2 = P l a n t a ti o n A r e. I
\�-----M
0
= Return o n Inve.tment
yields are lower. For a further analysis of the policy implications of continued hydroelec tric development within the Amazon Basin, environmental costs and energy benefits from an average dam such as Tucurui were calculated as a ratio of reservoir area to gen erating capacity. In areas of low topographic relief, the costs associated with hydroelectric dams are greater than comparable dams in high-relief landscapes, because the area of forest pro ductivity is greater and dam structure does not benefit from steep geologic formations. The most significant environmental costs of the Tucurui Dam, other than trapped sedi ments, were the losses of forest productivity, soils, and wood. Each of these losses can be related to the area of reservoir, and a simple ratio of the area of reservoir to generating capacity (ha/kW) can be calculated for a quick evaluation of the potential for positive net yield for other dam proposals (assuming that all other costs are unchanged and that the only variables are reservoir size and gen erating capacity) . Using emergy values of for est production and storages of soils and wood per ha and the emergy value of pro jected electricity from the Tucurui Dam project, we calculated a ratio of 2.1 ha/kW of generating capacity as the break-even point. The Tucurui Dam had a ratio of 2.4/1.
8
100
Time (yr) Figure 2 2 . 6
Productivity of the upper Sea of Cortez makes an important contribution to the economy of 24 E6 kg; Mexico through commercial fisheries. The upper Sea of Cortez supports more than 30% of Mexico's total fish and shellfish catch by weight. Shrimp are an important part of this catch, and it is generally assumed, based on work in other estuarine sys tems, that the Colorado River is an important component in stimulating productivity of the region. Yet the river's dis charge has been drastically modified during this century with seemingly minimal impact on the shrimp fishery. This study assessed what role, if any, the Colorado River may have in productivity of the upper Sea of Cortez and com pared the costs and benefits of two strategies for harvesting shrimp in the region (Brown et al. 1989). The emergy basis for the economy of the region is summarized in Table 22.7. Tides, ocean currents, and the Colorado River inflow are the largest emergy inputs, and fuels and goods account for about 17% of the total emergy inflowing.
Simulation results o f the model in Figure 2 2 . 5 under five dif ferent development intensities. Maximum values for parame ters are as follows: S A2
=
800 E3 ha; I
=
=
1
5 E8 m . t. ; M
E9 $ .
=
70 E6
$; N
Characteristics and emergy ratios for the Tucurui Dam are given in Table 22.6. The net yield ratio calculated with out consideration of sediments was 3/1. Conventional technologies for generation of electricity from fossil fuels yield on the order of 1.5/1 to 2.0/1; thus the higher yields from the hydroelectric facility suggest its potential contri bution to the economy of Brazil. However, if the electricity is used in place of fossil fuels for processes that are more suited to fuels, much of its potential goes unused. Under these circumstances, its benefit to the economy may not be as large as suggested above. The policy implications of net emergy analysis depend on how quickly the economy can adapt to using the energy surpluses from the facility. If wasted for numerous years as the economy adapts to the new energy source, net
=
The Upper Sea of Cortez and Colorado River, Mexico
M. T. BROWN ET AL.
228 Table 2 2 . 5
Emergy flows i n the region o f the Tucurui hydroelectric d a m o n the Tucantine River
Category, No. Name
Units/yr
Item
Transformity Change in Solar Emergy E l 8 sej/yr sej/unit
Economic Inputs
1 Dam
Embodied energy in imported services
9.20 E+07 $
3.80 E+1 2
349.6
2 Services
Embodied energy in debt service
3.70 E+08 $
6.70 E+1 2
2,479.0
3 Fuels
Fuels consumed in construction
2.90 E+1 5 J
6.60 E+04
191.4
4 Concrete
Concrete construction
3. 1 4 E+1 2 g
9.26 E+07
290.8
5 Steel
Reinforcing steel construction
1 .30 E+1 3 J
5 . 1 5 E+07
669.5
6 O&M costs
Annual operation and maintenance
1 .40 E+08 $
6.70 E+12
938.0
4,918.3
Total Economic Inputs Environmental Losses
7 Terrestrial production
Loss of gross primary production
2.00 E+1 7 J
8.94 E+02
1 78.8
8 Rain forest
Loss of wood due to inundation
1 .30 E+16J
3.84 E+04
499.2
9 Topsoil
Loss of soils due to inundation
1 .50 E+16J
7.38 E+04
1 ,106.3
Loss of potential energy in buried sediment
1.05 E+1 3 g
2.00 E+09
2 1 ,000.0
10 Sedimentation
22,784.3
Total Environmental Losses Environmental Inputs
1 ,900.0
1 1 Solar energy
Sunlight in region
1 .90 E+2 1 J
1
12 Rainfall
Rainfall chemical potential in the Tucurui powershed
1 .80 E+16J
1 .82 E+04
327.6
1 3 River flow
River physical energy
2.lO E+1 7 J
2.79 E+04
5,859.0
14 Aquatic production
Gross primary production in reservoir
5.00 E+16J
4.70 E+03
235.0
8,321.6
Total Environmental Inputs 1.00 E+17 J
15 Hydroelectrical Production
2.00 E+05
20,000.0
Source: From Odurn et al. 1986.
Table 2 2 . 6 Characteristics and emergy ratios of hydroelectric dam at Tucurui, Brazil
Item
Category Number 22.5
in Table
Net yield ratio
Value 3.02
14 + IS 1 + 2 + 3 + ... + 9
Net yield ratio with sediment included as a loss to the region
0.73
14 + I S
1 + 2 + ... + 9 + 10
1 04.50
Ratio of electricity to fuels consumed
IS
Upgrade ratio
1 + 2 + ... + 9 + 12
3
I S (actual Source: From Odurn et al. 1986.
J)
7.03 E4 sejlJ
Colorado River contribution to the upper Sea of Cortez. Diversion of the Colorado River to fill the Sal ton Sea in California reduced flow of the river to 0 between 1905 and 1907. Subsequently, the flow was reduced to fill Lake Mead behind Hoover Dam. In 1986, flow was about 33% of that recorded during the 1920s. To assess the maximum potential importance of river water and nutrients, y early flux was calculated for the "unal tered condition" of the river when there was relatively lit tle intervention by humanity, based on data from the 1920s. Inputs to and exports from the upper Sea of Cortez, are presented for water, organic matter, phos phate, and nitrate in Figure 22.8. During the 1920s period of "normal" flow, discharge of the river represented only about 0.01% of the total volume of water in the northern Sea of Cortez and yearly organic matter contribution from the river was only about 0.4% of the total volume of organic matter, based on extrapolations from data from Byrne and Emery (1960), Mann (1982), and McCleary
229
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
Figure 2 2 . 7
Energy analysis diagram o f hydroelectric dam at Tucurui. Numbers are keyed ment; C
=
cattle; ET
=
evapotranspiration;
P
=
(1986). The contributions of phosphorus and nitrogen in river water were likewise small when compared to total vol umes in the region, 0.01% and 0.02%, respectively (Alva rez-Borrego 1983; U.S. Geological Survey 1976). It would appear that river diversion and the resulting reduction of these constituents were buffered by the enormous stor ages within the region and that the work of tides (7 m) and the upwelled mobilized materials, which have accu mulated over millions of years, were sufficient to make the loss of river nutrients inconsequential. On a geological timescale, the Colorado River was likely to have been important to the region's productivity through deposition of sediment and nutrients, but its inflow or lack of inflow, on an annual basis, appears to be relatively insignificant. Considering the importance of the upper Sea of Cortez and the lack of data on the effects of inflow, estuarine pro cesses, and productivity, we urged the government of Mex ico to invest in a major scientific program to better understand the dynamics of the system. The Sea of Cortez shrimp fishery. Observations made during the Cousteau expedition suggested that the shrimp trawler fishery may not be sustainable due to the potential for overfishing, impacts on the ecosystem, and
to
Table 2 2 . 5 . Sed
=
sedi
price.
possible overcapitalization. Cousteau teams found trawl ers active long after the peak fishing season, because gov ernment subsidies encouraged fishing, whether or not economical, as a means of boosting employment. As a consequence, the by-catch of unusable fish and shellfish was as high as 90% of the total catch by volume after the season's peak. The number of boats and the frequency of trawl nets dragged over the bottom (mean: 6 times/yr) suggested a negative impact on the benthic system upon which the shrimp depend. Thus as we addressed the value of fisheries in this region and their sustainability, a num ber of economic and ecological factors were considered: the appropriateness of technologies employed, the impacts of energy-intensive technologies, the efficiency of extraction of resources, and the overall effects on the economy and ecology in both the short and long tenn. The older and more traditional fishing strategy involved the use of small boats with outboard motors (pangas) whereby shrimps were caught in nets for local consump tion. A newer and more intensive fishery involving greater capital and energy use employs shrimp trawlers that har vest primarily for export.
230 Table 2 2 . 7
M. T. BROWN ET AL. Emergy evaluation o f resource basis for Sea o f Cortez ( 1 980s)
Item
Units/yr
Transformity sej/J
Solar Emergy El8 sej/yr
Macroeconomic Value E6 1984 U.S. $
Renewable Resources (R)
Sunlight
5.60 E+20J
I
560.0
186.7
Wind, physical energy
4.74 E+1 7 J
1 ,496
709.1
236.4
Rain, chemical potential
4.90 E+1 6 J
18,200
891 .8
297.3
Tidal energy
6.90 E+1 6J
1 6,840
1 ,1 62.1
387.4
Tidal current
2.22 E+15J
27,870
61.9
20.6
Rivers, chemical potential
3.01 E+1 6 J
48,460
1 ,458.6
486.2
Runoff, chemical potential
1 .9 1 E+16J
48,460
925.6
308.5
Hurricane, physical energy
3.40 E+1 3 J
55,763
1 .9
0.6
Seismic activity
4.24 E+1 3 J
4.70 E+06
199.3
66.4
Rain
3.80 E+14J
19,000
7.2
2.4
Rivers
1 . 67 E+14J
19,000
3.2
l.l
Other runoff
9.15 E+1 5 J
19,000
1 73.9
57.9
Ocean
6.58 E+1 6 J
19,000
1 ,250.2
41 6.7
Rain
5.95 E+08 g
1 .3 1 E+I0
7.8
2.6
Rivers
8.10 E+08 g
1 .31 E+I0
10.6
3.5
Other runoff
5.07 E+08 g
1 .31 E+I0
6.6
2.2
Ocean
4.25 E+I 0 g
1 .3 1 E+1O
556.8
185.6
Rain
2.08 E+09 g
4.2 E+09
8.7
2.9
Rivers
1 . 18 E+I0 g
4.2 E+09
49.4
1 6.5
Other runoff
7. 14 E+09 g
4.2 E+09
29.9
1 0.0
Ocean
2.77 E+1 1 g
4.2 E+09
1 ,160.6
386.9
Exported Goods and Seroices
2 . 1 0 E+08 $
2.9 E+1 2
609.0
210.0
Taxes
2.96 E+06 $
2.9 E+1 2
8.6
3.0
Natural gas
1 .99 E+15J
48,000
95.5
31.8
Petroleum
5.33 E+1 5 J
66,000
351 .8
1 1 7.3
Coal
2.02 E+14J
40,000
8.1
2.7
Wood
1 .53 E+14J
41 ,000
6.3
2.7
Electricity
4.58 E+14J
2.00 E+05
91.6
30.5
Goods & services
4.80 E+07 $
3.80 E+12
182.4
60.8
Organic matter
Phosphate
Nitrate
Imports and Outside Sources
Source: Brown et al. 1989.
23 1
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
Ram Ram Other Runoff
Cotorado River Tidat Prism
1
0
4
Ie
--=---� 30
_
.6
Other Runoff
�
Evaporation
Colorado _--=,-,-_..j River Tidal Prism E xchange
. 464
---'=:=..--::;
Sedimentation
�---
0Exchange -30 30.-
W A TER FLOWS l E 9MJ/yr STORAGE lE9MJ
ltRIOVER 42Sdays
FLOWS l E90m/yr STORAGE l E9gm/yr
Rain
Rain
Colorado, _---"'=--_..j River
_-=2.::...4;..;.30"-----1 ___--'"' Sedimentation
FLOWS l E 9gm/yr STORAGE l E 9gm
Figure 2 2 . 8
2. 1
Other Runoff
Other Runoff -
Cotorado River
TURNOVER 420davs
Consumption l\.RI()VER 4 10daye
-..::.;!�;...--:::::>-,
Tidal Prism E xchange ---
FLOWS l E9gm/yr
Production
Consumption ltRIOVER 423day.
STORAGE l E9gm
Total storages a n d annual flows o f water (top left), organic matter (bottom left), phosphorus a s and nitrogen as
PC4 (top right),
N03 (bottom right) in the Sea of Cortez in the ' 920s.
A summary diagram of the upper Sea of Cortez is pre sented in Figure 22.9. Ocean currents, tides, and river inflows carrying organic matter and nutrients interact to generate a productive fishery based on flows of fuels, goods, and services. An emergy analysis of the two tech nologies used in the shrimp fishery is presented in Table 22.8 and Table 22.9. Included in the analysis are the renewable inputs that are estimated from the work of Odum and Arding (1 991) in Ecuador and purchased inputs derived from interviews of fishermen and the data collected by the Delegacion Federal de Pesca en Sonora, Departamento de Flota y Industria, Guaymas, Mexico. The transformity for shrimp in each analysis is calculated in the last row by dividing the total emergy inputs by the energy of the shrimp catch. Each of the technologies has a different transformity that results from the differences in total emergy inputs and yield of the two fishing methods. Comparisons between the two technologies and shrimp mariculture are presented in Table 22.1 0. The range of transformities reflects the different technologies; shrimp caught using trawlers has the highest transformity, and the pangas has the lowest. The emergy investment ratio (or ratio of purchased emergy to renewable emergy) is high est for trawlers. As a result of the low purchased inputs
Table 2 2 . 8
Emergy a n d shrimp yield per year: shrimp trawlers
Item
Units/yr
Transformity
' Renewable Inputs
Solar Emergy E15 sej/yr 152.0
Purchased Inputs
Fuel
7.2 E12J
66,000
480.0
Misc. goods and services
6.6 E4 $
2.9 E+12
190.6
Salary
1 .74 E4 $
2.9 E+12
48.3
Boat
4.1
E3 $
2.9 E+12
12.1
Engine
4. 1 E3 $
2.9 E+1 2
12.1 743.1
Subtotal ofPurchased Inputs Total Renewable and Purchased Emergy Inputs Shrimp Haroested
3.8 El 0 J 23.6 E+06 sej/J
895 . 1 895.1
Source: Mter Brown et al. 1989. ' Renewable inputs based on 4.0 E6 sej/J of shrimp (Odum and Arding 199 1 ) .
and high emergy of shrimp caught, the smaller traditional shrimping method has a net emergy yield ratio that is nearly three times that of the shrimp trawlers. The emergy analysis for trawlers does not include by-catch because these data were not collected by the Delegacion Federal
232
M. T. BROWN ET AL.
b y
products
Figure 2 2 . 9
Summary diagram o f the Sea o f Cortez shrimp fishery showing driving energies inflowing from left a n d bought goods and services and the economic sector to the right. N
Table 22.9 Emergy costs and shrimp yield per year: small boats (pangas)
Item
Units/yr
Transformity
44.0
Purchased Inputs
1 .35 El l ]
Misc. goods and services Salary Boat Engine
66,000
8.9
2.9 E+12
2.5 7.0
$24,000
2.9 E+12
$50
2.9 E+12
0.1
$271
2.9 E+12
0.8
Sublalal oj Purchased Inputs
19.3
Tolal Renewable and Purchased Emergy Inputs
63.3
1.1 EI0] 5.7 E+06 sejl]
Shrimp Harvested SOltrc,: Mter Brown et al.
!
$879
1 989. 4.0 E6 sejlJ of shrimp
Renewable inputs based on
nutrients; Sed.
=
sediments; B
(Odum and Arding
63.3 1 99 1 ) .
=
benthic organisms.
Table 22. 1 0 Summary indices and ratios for shrimp fishery of Sea of Cortez and shrimp mariculture in Ecuador
Solar Emergy E15 sej/yr
! Renewable Inputs
Fuel
=
Item
Ecuador Shrimp Shrimp Pangas Trawlers Mariculture 1 ------
Solar transforrnity (E6 sejlJ)
5.7
23.6
1 3.0
Emergy investment ratio
0.4
4.9
3.4
Net emergy yield ratio
3.3
1 .2
1 .3
! Data are from Odum and Arding 1991.
de Pesca. Based on interviews with fishermen and govern ment personnel, the by-catch was estimated from 5% to 90% depending on the season and the area fished; and if it were assumed to average 50% over the year and were included in the analysis, the net emergy yield ratio for trawlers would be reduced from 1.2/1 to about 0.75/1.
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
When viewed in the context of the maximum emergy principle, these data suggest efficiency is not the primary principle by which selective processes operate to allocate resources, but rather they operate so as to maximize the rate of resource use. In so doing, the larger system (in this case, the economy) maximizes emergy flow. Clearly, the data suggest that the panga is the more efficient fishing boat but is much less "productive" than the shrimp trawler in that a trawler can catch a larger amount of shrimp in a shorter period of time. All other things being equal, and as long as the costs of energy and machinery remain low, trawlers will continue to be used. On the other hand, their continued use does not address sustainability or the future availability of energy and machinery. Overfishing and hab itat destruction from overtrawling may undermine the capacity of the population to regenerate. Without a pro ductive, balanced population, the fishery cannot sustain high catch rates nor support the high economic invest ments in trawlers that are currently being made. Current costs of energy and machinery and the current abundance of shrimp in the region favor energy-intensive processes for harvest. Yet if either of these two factors changes (Le., if energy costs rise or shrimp populations decline), the ability of the fishery to sustain high economic investment is diminished. Conditions may then once again favor the smaller, more efficient pangas. The overall economic consequences of increased exploitation and export of the shrimp fishery are com plex. As a resource like the shrimp population in the upper Sea of Cortez is increasingly exploited, local mar kets generally are not large enough or developed enough to accommodate the expanding supply. As a conse quence, prices fall. If sales were limited to the local mar kets, the size of the fleet would rapidly adjust, and exploitation would track the ability of the local market to consume the resource. However, where large outside mar kets can be found, demand and prices rise higher, and the local markets in effect are competitively excluded. Under these circumstances, production increases to meet demand and a cycle of increasing dependence on exter nal markets is initiated. It is difficult if not impossible to break dependence on external markets because local demand for the resource is kept low by the higher prices of outside markets. Costs associated with exploiting the resource increase as the technology increases, and even tually, one can no longer "afford" to sell the resource locally because the local economy cannot support the price that must be asked. The export of shrimp to foreign markets illustrates the problem that many developing countries face as they develop, extract, and sell their raw resources. The trade advantage usually goes to the trading partner purchasing the raw resource. In general, the emergy per dollar of raw resources is higher than that for finished goods. Trade advantage can be estimated by comparing the emergy per
233
dollar of one commodity to that of another commodity. When the emergy per dollar of shrimp caught using trawl ers (52.6 E12 sej/$) is compared with an average "mix" of goods purchased from the United States (2.4 E12 sej/$), the trade advantage to the United States is about 22/1 (52.6 E12/2.4 E12). Although in this case the trade advantage is clearly in the favor of the United States, the local economy is expanded as the local population is involved in exploit ing, processing, and transporting the product. As a result, most policymakers believe that the net effect is positive, even though external markets become increasingly influ ential. The money derived from exports of the resource is used to purchase external goods, services, and energy that in turn increase the standard of living locally and increase the ability to exploit the resource even further. But in the rush to increase the economic cycles of exports and imports, the local economy is often shortchanged as the emergy of the harvested resource contributes less to the home economy than to that of the economy that imports it. Although the national economy may benefit from exports in the context of balance of payments and national debts, the local economy suffers. The challenge is to integrate internal and external economies to provide benefit to local people and to protect the resource from overexploitation.
Papua New Guinea (PNG) Unlike many developing countries, PNG has retained much of its natural resources and traditional culture, giv ing it options and opportunities few other countries on the planet enjoy. The energies of plate tectonics provide geological uplift and rich soils; latitude offers abundant sunlight and rainfall; and historical isolation has permit ted the retention of knowledge embodied in culture that in many cases fosters uses of and respect for nature, long since lost in other cultures. With coral reefs and exten sive rain forests, many people enjoy a sense of perma nence and predictability and a lifestyle that, based on energy criteria, is of high quality. A significant portion of the population still lives outside the monied economy, and the economy is not as yet driven by external market and political forces. Yet as its population and supporting economy grow, PNG is increasingly drawn into the greater world economy through imports and exports, posing serious questions as how to best manage its resources, lands, and people. Based on our experience elsewhere, there is a strong potential for a developing economy, like that of PNG, to rely on the sale of exported raw materials to finance needed imports of goods, service, and advanced technol ogy. As a result, lands and resources are often regarded as valuable only if they can be exploited and sold and are perceived as having little or no value when left in place as a functioning ecologic-economic system. In such cases,
234
the developing economy often does not allow for the slow integration of indigenous cultural patterns that are driven by renewable resources; instead, development quickly replaces these economies with a monied one that is driven to a greater degree by fossil fuels and imported goods and services. Finally, the developing economy, in its rush to increase standards of living by importing more and more from external markets, is increasingly financed through the exploitation of internal resources, which undermines the ecological stability and productivity of its support base. In the long term, this actually decreases the quality of life for large portions of the population. As more indi viduals are brought into the monied economy, greater impact on the natural resource base and consequent declines in the carrying capacity of the natural environ ment result. Larger numbers of people are forced to depend upon the monied economy. Although examples of these negative consequences can be found in PNG with the mining of copper, gold, and sil ver and to varying degrees with forestry and fisheries projects, more than anywhere else the Cousteaus have explored, the opportunities to prevent negative conse quences of development and to guide future development far exceed the need to cure and restore. Consequently, our work in PNG has been to evaluate indigenous resources of the country as a whole to rank and compare PNG to other, more developed nations and lend insight into policy questions related to export of resources and international trade (Brown et al. 1991). An important goal has been to quantify the value of resources that lie outside the monied economy and thus may not be appre ciated from the perspective of traditional economists but that still contribute to the quality of life for the people of PNG. Emergy storages and flows, presented in Table 22.11, were calculated based on the energy systems dia gram shown in Figure 22.10. Flows and processes evalu ated are environmental inputs, flows of money, human roles, and international exchanges. The high elevations of PNG's central cordillera (several peaks are over 3,000 m) and the role of increased rainfall and decreased evapotranspiration rates with increasing elevation led us to consider the emergy contributions of precipitation as the sum of two separate analyses of the Highlands and Lowlands regions. The Highlands repre sent 56% of the land area of PNG, with an average eleva tion of 999.6 m, 3.73 m of rainfall annually, and a 10% evapotranspiration rate (ET). The Lowlands represent the remaining 44% of the land area, with an average elevation of 150 m, 1.20 m of rain, and an 80% ET rate due to less steep slopes (i.e., lower runoff) , lower cloud coverage, and higher winds creating greater convection currents. Based on these conditions, the Highlands contribute 756 E+20 sej/yr from geopotential energy in rain to the country 's economy, meaning almost 98% of this potential is due to the conditions of the Highlands' elevation. In
M. T. BROWN ET AL.
contrast, the major energy contribution (280 E+20 sej/yr) in the Lowlands is the chemical potential energy in rain fall, because the elevation is so much lower and total vol ume of water transpired is so much greater. Using this analysis of the subregions emphasizes the important role of high annual rains and the steep slopes of the High lands. The geopotential energy of rainfall is the predomi nant solar-based flow contributing to the country's annual emergy basis. Each y ear, more of PNG's agricultural cropping systems are being converted to cash crops, such as coffee, copra, cocoa, and oil palm grown primarily for export. Yet most of PNG's inhabitants, perhaps 80%, still rely either directly or indirectly on subsistence cultivation as the mainstay of their diet. These trends are reflected in the emergy analysis (Table 22.11), in which agricultural pro duction represents the country 's greatest renewable resource and only about 15% of that emergy is exported. This further complicates economic analyses of the coun try's productivity, measured in microeconomic terms, because there is little money circulating within these sub sistence patterns even though there may be considerable beneficial activity taking place. A summary diagram of emergy flows of PNG is pre sented in Figure 22.11, and overview indices are listed in Table 22.12. Although a balance of payments in monetary terms for imports and exports existed in 1988, the emergy balance of payments �as negative. Over ten times the emergy in imports was exported (51.5 E20 sej/yr imported and 598 E20 sej/yr exported). The United States, in contrast, receives over two times as much emergy in imports as in exports. This scenario is sometimes typical of developing nations with large resource bases, which in their struggle to compete in the global market rely on the sale of their raw materials for necessary finances to pur chase outside goods and services. Emergy and economic indices give a sharply contrasting perspective of PNG. Economically, the GNP of PNG sug gests it is an impoverished country with a relatively low qual ity of life. Yet emergy use/person and emergy/GNP are among the highest for any country in the world. Obviously, the difference is that rich natural resources in PNG (i.e., indigenous emergy flows and storages) are traditionally not considered part of the economic system and are not included in analysis of the monied economy. Based on this emergy analysis, however, we conclude that people living outside the monied economy have a relatively high stan dard of living and that plans for future development in PNG should take this into consideration. Of primary importance, we believe that proposals for development projects should factor in the value of indigenous emergy flows and storages in the maintenance of standard of living of rural populations. The long-term loss of forest productiv ity and storages of soils is often not offset by the short-term economic gains made from the sale of clear-cut timber.
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS Table 2 2 . 1 1
235
Emergy evaluation of resource basis for Papua New Guinea ( 1 987)
Transfonnity sej/unit
Solar Emergy E20 sej/yr
Macroeconomic Value E9 U.S. $ ( 1 983)
Units
Units/yr
Sunlight
J
2.59 E+21
25.9
1.1
Rain, physical energy
J
8.57 E+18
10,490
899.0
37.5
Rain, chemical potential
J
3.30 E+18
1 8,200
600.6
25.0
Wind, physical energy
J
1 .34 E+18
1 ,496
20.1
0.8
Wave energy
J
6.1 5 E+17
30,550
1 88.0
7.8
Tidal energy
J
1 .23 E+18
1 6,840
207.3
8.7
Earth cycle
J
1 .85 E+18
6,055
1 1 .0
4.7
Item Renewable Resourr:es (R)
Indigenous Renewable Energy
Hydroelectricity
J
1 .08 E+15
70,300
0.8
0.0
Forest extraction
J
9.42 E+15
40,000
3.8
0.2
Fuelwood products
J
5.71 E+16
41 ,000
23.4
1.0
Agriculture products
J
3.97 E+16
95,000
37.7
1 .6
Livestock
J
1.58 E+15
2.00 E+06
31.6
1 .3
Fisheries
J
1 .38 E+14
2.00 E+06
2.8
0.1
Electrici ty
J
5.37 E+15
10.7
0.5
Copper
Indigenous Nonrenewable Sourr:es (N)
200,000
g
1 .75 E+1 1
6.80 E+I0
1 19.0
5.0
Gold
g
1 .45 E+07
4.40 E+1 4
63.8
2.7
Silver
g
3.68 E+07
3.00 E+14
1 10.4
4.6
Topsoil losses
J
1.43 E+17
73,750
105.5
4.4
Oil
J
2.80 E+16
66,000
18.5
0.8
Phosphorus (fertilizer)
J
1 .49 E+1 1
6.00 E+07
0.1
0.0
Nitrogen (as NHg)
J
6.50 E+l l
1 .70 E+06
0.0
0.0
Potash (fertilizer)
J
4.09 E+I0
7.00 E+06
0.0
0.0
Services
US $
9.63 E+08
3.80 E+12
36.6
1 .5
Goods
US $
5.13 E+08
3.80 E+12
19.5
0.8
py l
9.28 E+03
3.45 E+16
3.2
0.1
Tourism
US $
5.85 E+06
2.60 E+06
0.2
0.0
Foreign aid
US $
9.46 E+08
3.80 E+12
36.0
1.5
Cash crops
J
5.52 E+15
9.20 E+04
5.1
0.2
Fisheries products
J
4.86 E+13
2.00 E+06
1 .0
0.0
Forestry products
J
4.91 E+15
4.30 E+04
2.1
0.1
Imports and Outside Sources
Net immigration
Exports
Copper
g
1 .75 E+1 1
6.80 E+I0
1 1 9.0
5.0
Gold
g
1 .45 E+07
4.40 E+14
63.8
2.7
Silver
g
3.68 E+07
3.00 E+14
1 10.4
4.7
US $
1 .03 E+09
5.75 E+13
592.3
24.7
Services l People per year.
236
M. T. BROWN ET AL.
ET
Papua N e w Guinea
Figure 22. 1 0
Table 2 2 . 1 2
Energy diagram of Papua New Guinea.
L
=
land; P
=
price; ET = evapotranspiration.
Overview indices of Papua New Guinea ca. 1 987
Description
Expression1
Renewable emergy flow
R
1 ,2 1 8.2
E20 sej/yr
Flow from indigenous nonrenewable reserves
N
436.6
E20 sej/yr
Flow of imported emergy
F+G+P21
74.7
E20 sej/yr
Total emergy inflows
R+N+F+G+P21
1 ,729.4
E20 sej/yr
Total emergy used, U
NO+N1+R+F+G+P2 1
1 ,436.2
E20 sej/yr
Total exported emergy
N2+B+P1 E
893.6
E20 sej/yr
Fraction of emergy use derived from home sources
(NO+N1+R) /U
Imports minus exports
(F+G+P21 )-(N2+B+P1 E)
-818.9
Ratio of export to imports
(N2+B+P1E) I (F+G+P2l )
0. 1
Fraction used, locally renewable
R/U
Fraction of emergy use purchased
(F+G+P21 ) /U
5.0
percent
Fraction imported service
P2l/U
3.0
percent
Fraction of use that is free
(R+NO)/U
Ratio of concentrated to rural
(F+G+P21 +N 1 ) / (R+NO)
6.0
percent
Emergy use per unit area
U/ (area)
3.1
El l sej/m2
Quantity
95
85
94
Units
percent E20 sej/yr percent percent
percent
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
237
E 1 21/yr
E 2 0 a ol a r e m j o u l . a / y r
(a)
11 1.11
I n d l g_ n o u . .ouree. R . N · N 1 N2 O
14117.11
P. N.G.
1187.11
Figure
Expor" N ·B.P E 3 l 2
22. I I
Summary diagram
of the
emergy flows of Papua New Guinea.
Flows
of emergy
are from Table 22 . 1 1 ; letter symbols in the figure refer to expressions in Table 2 2 . 1 2 .
(b) Table 2 2 . I 2 (Cont'dj
Overview indices of Papua New Guinea ca. 1 987
Description
Expressioni
Emergy use per person
U I (population)
4.5
EI6 sej/per
Renewable carrying capacity at current living standard
(R/U) (population)
2.7
E6 people
Ratio of use to GNP, emergy:money ratio
PI
U/GNP
5.7
EI3 sej/$
Electricity use as fraction of total emergy use
(electric) IU
5.0
percent
Fuel use per person
fuel/population
I Letters
=
Quantity
16.7
Units
EI4 sej/per
in each expression refer to pathways in Figure 22.1 I .
We encouraged PNG to mimmize exports of raw resources and develop means of internally processing and upgrading them. Exports of raw materials carry high emergy/$ received from their sale. Thus the imbalance between the emergy in the exported resource and the emergy that can be purchased with money obtained from its sale is large. Far more emergy is exported than is pur chased and imported. Countries that import the raw
resource receive the benefit of trade. With the restraint of export of raw materials, the prices of these materials at home drop, which may attract investment in the plants and machinery necessary to process the resources. This in turn creates jobs for a country's own people, thereby stim ulating its own economy rather than the economies of the purchasing countries.
238
M. T. BROWN ET AL.
Migration
T h a i l and
Figure 2 2 . I 2
Energy diagram of Thailand showing rural populations and their relationships to forested and agricultural lands and the importance of religion. Pop
=
people; Sed.
=
Thailand Thailand faces challenges found in most developing tropi cal countries. Overpopulation exerts pressure to convert forest to farmland, and external markets and the lure of foreign goods drive the cutting of forests for the export of wood. These activities contribute to topsoil depletion and reduced water retention, which affects agricultural sus tainability and downstream hydrology. A decline in carry ing capacity of the landscape, an increase in population, and excess farm labor cause people to flee to cities like Bangkok, thus overloading urban systems. Thailand is attempting to meet these challenges by improving the productivity of the landscape through hydropower and irrigation projects and integrated farming techniques. At the invitation of His Majesty King Bhumibol Aduly adej of Thailand, the Cousteau/Odum team had an opportunity to collect data and help evaluate alternative sites for a hydropower/irrigation project on the Mekong River (McClanahan and Brown 1991). This analysis will help decision makers choose between the two alternatives and serve to demonstrate energy analysis techniques as a tool for evaluating and managing resources.
sediments; ET
=
evapotranspiration.
An aggregated diagram of Thailand, emphasizing the inputs of sun, rain, rivers, geologic uplift, and imported goods and services, is given in Figure 22.12. Production within the country includes forests, agriculture, and aquaculture, as well as industry and commerce. Energy, transformities, emergy, and the macroeconomic values of the annual flows of this energy are presented in Table 22.13. When evaluated using emergy, the chemical potential of rain is the most important renewable resource. Animal husbandry (livestock), agriculture, and fisheries are the most important forms of renewable pro duction. Important indigenous nonrenewable resources include natural gas, oil, lignite, limestone, and topsoil (which is eroded at a high rate). Major imported emer gies include oil, phosphorus, nitrogen, food, wood, pesti cides, mechanical equipment, and vehicles. Associated with these goods is a very high emergy imported as for eign services. At the present time, hydroelectric produc tion is more than 40% of the emergy budget derived from fuels and hydroelectric sources. That Thailand is still chiefly an agricultural economy can be seen from the large annual emergy contributions from agricultural and
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS Table 22. 1 3
23 9
Emergy evaluation of resource basis for Thailand ca. 1 984
Item
Units
Units/yr
Transformity sej/unit
Solar Emergy E20 sej/yr
Macroeconomic Value E9 U.S. $ ( 1 984)
Renewable Resources (R)
Sunlight Rain. physical energy Rain. chemical potential Wind. physical energy Wave energy Tidal energy Rivers. physical energy
J J J J J J J
2.88 E+21
1
28.8
1 .2
2.l6 E+18
10.490
226.6
9.4
4.77 E+18
18.200
868.1
36.2
2.38 E+18
1.496
35.6
1.5
24.20 E+17
30.550
128.3
5.4
4.42 E+16
16.840
7.4
0.3
2 1 .31 E+17
27.870
36.5
1 .5
5.05 E+16
7.03 E+04
35.5
1 .5
1 .47 E+16
4.00 E+04
5.9
0.3
9.35 E+15
4. 10 E+04
3.8
0.2
9.96 E+17
9.50 E+04
946.2
39.4
6.28 E+16
2.00 E+06
1 .256.0
52.3
3.68 E+16
2.00 E+06
736.0
30.7
Indigenous Renewable Energy
Hydroelectricity Forest extraction Fuelwood products Agriculture products Livestock Fisheries
J J J J J J
Indigenous Nonrenewable Sources (N)
Natural gas
9.41 E+16
4.80 E+04
45.2
1.9
8.42 E+16
6.60 E+04
55.6
2.3
Lignite
J J J
5.42 E+16
3.70 E+04
20.1
0.8
Gypsum
g
3.40 E+l l
1 .00 E+09
3.4
0.1
Limestone
g
8.70 E+12
1.00 E+09
87.0
3.6
Topsoil losses
J
7.24 E+16
7.38 E+04
53.4
2.2
J J J J J J J J J J
5.00 E+16
6.60 E+04
33.0
1 .4
3.75 E+l l
1 .40 E+08
5.3
0.2
U.S. $ py l
1 .06 E+10
3.80 E+12
402.8
16.8
9.28 E+03
3.45 E+16
3.2
0.1
Cash crops
U.S. $
2.48 E+17
9.50 E+04
235.6
9.8
Fisheries products
U.S. $
5.68 E+15
2.00 E+06
1 1 3.6
4.7
Forestry products
U.5. $
1 .28 E+15
4.10 E+04
0.5
0.0
g
3.29 E+02
1.00 E+09
0.0
0.0
Petroleum
Imports and Outside Sources
Petroleum Steel Phosphorus Nitrogen Potash Food Plastics Pesticides Wood. paper. text Mech. and transport equip. 5enrices Net migration
5.84 E+l l
5.15 E+07
0.3
0.0
8.29 E+12
6.00 E+07
5.0
0.2
1 .28 E+14
1 .70 E+06
2.2
0.1
8.63 E+12
7.00 E+06
0.6
0.0 0.3
7.24 E+15
8.50 E+04
6.2
1 .84 E+13
6.60 E+04
0.0
0.0
1 .85 E+14
1 .00 E+06
1 .9
0.1
1 .04 E+16
4.40 E+04
4.6
0.2
Exports
Fluorite Gypsum
g
8.70 E+l l
1 .00 E+09
8.7
0.4
Limestone
g
1 . 1 0 E+12
1 .00 E+09
1 1 .0
0.5
Barite
g
3.47 E+02
1 .00 E+09
0.0
0.0
Services
U.S. $
7.15 E+09
3.69 E+12
263.8
1 1 .0
Tourist services
U.S. $
1.16 E+09
3.66 E+12
42.5
1 .8
Source: Mter McClanahan and Brown 199 1 . 1 People
per year.
240
M. T. BROWN ET AL.
E2 0 s o l a r e m J o u l e s / y r
E9 $ / y r
(a)
Ind igenous s o u rc e s R , NO , N N 2 1
1 1 69.9
Thailand
(b) Figure 22. 1 3
Overview diagram of the economy of Thailand. Flows of emergy are from Table 2 2 . 1 3; letters on pathways refer to expressions in Table 2 2 . 1 4 .
fisheries production. The economy as a whole is domi nated by these flows. Cash crops are the single most important export commodity, followed by fisheries exports (primarily aquaculture products). Figure 22.13 summarizes emergy flows, and Table 22.14 gives emergy indices of Thailand's economy. Thai land's ratio of emergy use to GNP (3.69 E12 sej/$) is near the world average, suggesting its position at the boundary between developed and less developed coun tries. Its ratio of emergy use per person (2.53 E15 sej/
person) is relatively low, reflecting a relatively poor national economy. The ratio in the United States is 29 E15 sej/person, and that of the world average is about 1.6 E15 sej/person. In regions of high indigenous renew able emergy flows (like Papua New Guinea) where popu lation levels are low, the ratio of emergy use per person may be quite high (34.7 E15 sej/person), suggesting there is much emergy flow to support the quality of life for the population despite a relatively undeveloped economy.
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS Table 2 2 . 1 4
24 1
Overview indices of Thailand ca. 1 985
Description
Expressionl
Renewable emergy flow
R
875.6
E20 sej/yr
Flow from indigenous nonrenewable reserves
N
284.3
E20 sej /yr
Flow of imported emergy
F+G+P2 1
461 .7
E20 sej/yr
Total emergy inflows
R+N+F+G+P21
1 ,621.6
E20 sej /yr
Total emergy used, U
NO+N1 +R+F+G+P21
1 ,601 .9
E20 sej /yr
Total exported emergy
N2+B+P1E
1 ,025.4
E20 sej/yr
Fraction of emergy use derived from home sources
(NO+N1+R)/U
Imports minus exports
(F+G+P21) - (N2+B+P1E)
Ratio of export to imports
(N2+B+P1E)/ (F+G+P21 )
Fraction used, locally renewable
Units
Quantity
71 . 1 -563.7
percent E20 sej/yr
2.2
percent
R/U
54.6
percent
Fraction of emergy use purchased
(F+G+P21 ) /U
28.8
percent
Fraction imported service
P21/U
25.1
percent
Fraction of use that is free
(R+NO)/U
58.0
percent
Ratio of concentrated to rural
(F+G+P21+N l ) / (R+NO)
72.4
percent
Emergy use per unit area
U/(area)
2.15
E l l sej/m2
Emergy use per person
U I (population)
2.53
E15 sej/pers
Renewable carrying capacity at current living standard
(R/U) (population)
Ratio of use to GNP, emergy:money ratio
PI
Fuel use per person
fuel!population
=
U/GNP
34.4 3.69 160.65
E6 people E 1 2 sej/$ E 1 4 sej /pers
Source: Mter McClanahan and Brown 1991.
l Letters in each expression refer to pathways in Figure 22.13. Other important indices from Table
22.14 are related
to the fraction of the economy that is from various sources. The fraction of emergy use derived from indige nous sources is nearly
70% of the total emergy budget, and the fraction that is renewable is almost 50% of the total. Over 30% of total emergy use in Thailand is pur
benefits of the two locations. An emergy analysis of both dams was conducted to lend additional insight.
An overview diagram of the proposed dams on the 22.14) shows that the main costs are loss
Mekong (Figure
of area for agricultural production and the displacement of rural households. The primary benefits are electricity
chased from outside the economy. The ratio of exports to
generation for use in urban and rural households and for
imports is about
manufacturing.
2.22/1, suggesting that the "emergy bal
A second important benefit of the dam
ance of payments" for Thailand is positive. Like many
projects is increased irrigation.
economies, however, Thailand's balance of payments,
Emergy analyses of both dams ( Table 22.15 and Table 22.16) include the potential dam benefits (electricity,
when evaluated in money, is negative-to be expected where emergy balance is positive, because money and emergy flow in opposite directions.
Mekong Dam analysis.
The Mekong
aquatic productivity, and irrigation supporting farm pro duction) and losses, including the direct costs of dam and
River
forms
irrigation system construction, losses of agricultural pro
the northern boundary between Thailand and Laos until it
ductivity, and losses associated with human population
Nations-sponsored initiative to develop the hydroelectric
span; thus construction costs were divided by
flows eastward through Cambodia. As part of a United
resettlement. The dam is assumed to have a
50 yr life 50 to
potential throughout the Mekong Basin, proposals for
present data on a yearly basis. The analysis indicates that
dams along the main reaches in the upper basin have been
electricity production by far is the major emergy benefit of
made. Among the first of these proposals involved two sites
dam construction. Irrigation and, to a much lesser extent,
in northern Thailand known as the Upper Chiang Khan
aquatic productivity are relatively unimportant. The analy
and Lower Pa Mong dams. Numerous studies evaluating
sis assumes that irrigation has the effect of doubling the
both sites have been conducted over the past decade as the
annual yield of crops through dry season irrigation. Irriga
governments involved have tried to reconcile costs and
tion has a very high benefit! cost ratio, but its inclusion in
242
M. T. BROWN ET AL. Table 2 2 . 1 5
Emergy evaluation of the Upper Chiang Khan Dam
Item
Transformity sej/unit
Units/yr
Solar Emergy E20 sej/yr
Macroeconomic Value E6 U.S. $ (1984)
New Products
Electricity
3.20 E+1 6J
200,000
64.0
Aquatic Product Irrigation (ag. equiv.)
3.8 E+15 J
4,700
0.2
4.9
8.63 E+1 1 g
6.43 E+08*
5.6
150.4
69.7
1,889.7
Total**
1 ,734.4
Inputs Required
Concrete
1 . 1 0 E+1 1 g
9.26 E+07
0.1
2.8
Steel
1.19 E+08 g
4.65 E+09
0.0
0.2
Machinery
4.16 E+08 g
1 .25 E+I0
0.1
1.4
Goods & services
3.20 E+07 $
3.80 E+1 2
1.2
33.0
Ag. product (rice)
3.47 E+I0 g
6.43 E+08*
0.2
6.1
Ag. product (maize)
1 . 1 4 E+1 5 J
4.75 E+04
0.5
14.7
Resettlement
1 . 65 E+08 $
3.80 E+1 2
6.3
1 69.9
Irrigation (Goods & Services)
1 .20 E+07 $
3.80E+1 2
0.5
1 2.4
8.9
240.3
Total* * Net Yield Ratio:
69.7 E20 sejlyr 8.9 E20 sejlyr
7.86 _ - -1
*An average of high/low technology rice production (8.3 E8 + 4.6 E8) / 2 **Totals may be different due to rounding off numbers. Source: Mter McClanahan and Brown 199 1 . Table 2 2 . 1 6
=
6.4 E8 sej/g
Emergy evaluation of Low Pa Mong Dam and irrigation
Item
Transformity sej/unit
Units/yr
Solar Emergy E20 sej/yr
Macroeconomic Value E6 U.S. $ (1984)
New Products
Electricity
3.62 E+1 6 J
200,000
72.4
1 ,962.1
Aquatic Product
9.30 E+15 J
4,700
0.4
1 1 .9
Irrigation (ag. equiv.)
1 .44 E+1 2 g
6.43 E+08*
Total**
9.3
250.9
82.1
2,224.8
Inputs Required
Concrete
1 .35 E+1 1 g
9.26 E+07
0.1
3.4
Steel
2.31 E+08 g
4.65 E+09
0.0
0.3
Machinery
6.66 E+08 g
1 .25 E+lO
0.1
2.3
Goods & services
4.20 E+07 $
3.80 E+12
1 .6
43.3
Ag. product (rice)
1 .23 E+1 1 g
6.43 E+08*
0.8
2 1 .4
Ag. product (maize)
7.42 E+1 4 J
4.75 E+04
0.4
9.6
Resettlement
1 .65 E+08 $
3.80 E+1 2
6.3
1 69.9
Irrigation (Goods & Services)
4. 1 6 E+03 $
3.80 E+1 2
9.2
250.1
Total** Net Yield Ratio:
82. 1 E20
sejlyr
9.2 E20 sejlyr
_
8.9
- 1
Source: Mter McClanahan and Brown 199 1 .
*An average o f high/low technology rice production (8.3 E 8 + 4.6 E8) / 2 **Totals may be different due to rounding.
=
6.4 E 8 sej /g
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
243
H y d r o e l e c t r i c Development on the Mekong River
Figure 2 2 . 1 4
Energy diagram of relationships between urban and rural populations and the proposed hydroelectric dams on the Mekong River. ed. sediments; B biomass; P price. =
=
the development project is not important in determining the net emergy of the project because the emergy value of electricity produced is more than an order of magnitude greater than the expected agricultural production. The most significant costs associated with the dam construc tion are resettlement followed by goods and services. Lost agricultural production is significant but is more than made up for with increased production resulting from irrigation of other lands. Overall, both dams have positive net emergy yield ratios. The Low Pa Mong site has a better ratio (8.9/1) than the Upper Chiang Khan site (7.9/1). This is attributable to the greater projected electricity pro duction capacity of the Low Pa Mong site, which is not overridden by the lost agricultural productivity caused by its greater land requirements. Unlike the hydroelectric dam at Tucurui in the Amazon (whose net yield ratio is 3.0/1 when sediment loss is not included and less than 1 when it is included) , both of the proposed Mekong dams will contribute significantly to the emergy available to the economy because their ratios are between 7 and 9 to 1.
=
Several factors will influence the net emergy yield of the Mekong dams. First, the life expectancy used in our analysis was 50 yr, and if efforts are not made to reforest and protect the upstream watershed (which for the most part is out of the jurisdiction of the Thai government) from further degradation, the useful life of the dams could be shortened and net yields reduced. Second, there are potential downstream impacts (agricultural and wet land productivity) that may result from the loss of wet-sea son flooding, especially in the delta region of Vietnam. Our analysis of river volume upstream of the dam sites compared to the discharge in Vietnam suggested that the vast majority of hydrologic inputs to the river occurred downstream of the dam locations. Thus we did not con sider these impacts to be important. Finally, the loss of sediments, like the loss of wet-season flooding, could neg atively influence productivity in the lower reaches of the river; yet, like our analysis of the river's hydrology, sedi ment contributions below the dam sites were far greater than the upstream sediment load and therefore were not considered in the analysis. These factors should be
244
accounted for in analysis of other dams. They should be proposed in the lower reaches because altered flooding regimes and sediment inputs to the delta and estuary could ultimately decrease their net emergy yield to the overall economy of Southeast Asia.
Summary Development Projects Emergy analysis of the costs and benefits of construction projects such as dams is relatively straightforward. The maximum power principle (Lotka 1 922a; Lotka 1 922b; Lotka 1 945; Odum 1 971 : Odum 1 983a; Odum 1 983b) sug gests that self-organization processes will reinforce the one that increases the emergy use of the landscape. The Tucurui Dam in the Amazon Basin and the Lower Pa Mong Dam on the Mekong River appear to be viable development projects based on their net yield ratios. This conclusion hinges on two assumptions: (1) the human sector will be able to upgrade quickly and sufficiently to take advantage of the high-quality electricity that is pro duced and (2) the accumulation of sediments at Tucurui does not significantly reduce productivity in downstream aquatic and estuarine areas. Clearly indigenous peoples have contributed to the evolution of our planet's landscape, including that in the Amazon Basin, through the harvest of natural resources. Ecological theory suggests that these consumers added another link in the food web, increased ecological com plexity, and contributed to hierarchial organization of the system. As modern humanity increases resource exploita tion and system manipulation, they may also increase complexity and hierarchy. The challenge will be to bal ance these activities with the system's ability to assimilate and regenerate. The forestry plantation atJari in the Ama zon Basin may be an example of such a balance if man aged properly. Calculating emergy in ecologic and economic components of the system has helped us to quantify, on the same scale, very different system compo nents from rain and forest productivity to human services. Their evaluation in emergy terms suggested that the loss of soils and consumption of rain forest wood for the gen eration of electricity depleted those storages, and thusJari was not sustainable without increased imports of nutrients and energy. Simulations of models of Jari helped to show temporal behavior and allowed for manipulation of rela tionships of components in a search for a configuration that maximizes landscape emergy. We acknowledge that simulation models cannot replicate the complexity of the real world, but this was not our goal. Rather, through the use of "macroscopic minimodels," we hoped to reduce much of the real-world complexity to the most important components and thus focus attention on the major forces that drive the system.
M. T. BROWN ET AL.
Figure 22. 15 presents summary diagrams of Jari, the Tucurui Dam, the Sea of Cortez, and Papua New Guinea, showing the main flows of renewable and purchased ener gies and yields. Illustrated are three different spatial scales that can be classed by the order of magnitude of renew able emergy flow: a regional scale Uari), two supra regional scales (Tucurui and the Sea of Cortez), and a national scale (Papua New Guinea). Each diagram depicts how inputs from renewable resources are amplified by flows of purchased energy to develop a yield. AtJari (Fig ure 22.15a), pulp products are sold internationally, and energy, goods, and services are purchased with the money received from their sale. At the Tucurui Dam (Figure 22.15b), the inputs of purchased energy interact with renewable resources to generate electricity. In the Sea of Cortez (Figure 22.15c), large yields from the more energy intensive trawlers necessitate export of harvested shrimp to international markets. And in Papua New Guinea (Fig ure 22.15d), much national wealth is exported yearly from their marine fishery and rain forests and as minerals. Table 22. 1 7 summarizes the main impacts of development in these four areas and Thailand. Table 2 2 . 1 7 Emergy and macroeconomic evaluation of impacts. Macroeconomic values derived from Emergy. Ednergy �acroecononUc E18 sej/yr E6 $/yr I
Jan
Net wealth exported as pulp product
1 ,390
121
433
38
21 ,000
1 ,826
1 79
16
1,106
96
Rain forest wood lost
499
43
Electricity produced
2,000
1 ,739
250
74
3,919
1 ,1 52
211
4
Net wealth exported as fisheries products
97
2
Net wealth exported as mineral products
2,932
56
Agriculture production lost
114
30
Population resettlement
627
165
7,240
1,905
Virgin storage depleted II
Tucurui
Sediments diverted Environmental productivity reduced Topsoil lost
III Sea a/ Cortez (3. 4 E12 scj/$, Mexico)
Net wealth exported from shrimp fishery Losses due to Colorado River diversion N
Papua New Guinea
Net wealth exported as forest products
V Mekong Dams
Electricity produced
The question of sustainable development of resources is illustrated by the relationship shown between wealth
245
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS
.-_---::;;....__-..;.3l1li.2.;..;.;..- Purchased 7
Resources
- ' ...: ..:.; U=-- Goods and Services .-__-I----.....-....
Local Environmental Inputs
' __ =_ 1--';';
117� >-"";;';=---1
Paper and Lumber
(a)
11et7
__----- Purchased Resources __---..; :rr .:..;. � Goods and Services Local Environment al Inputs
111111A1
':>-----=:..=:::.-.--1
Tucurui Dam
1-
---'= 2000 � 0 � Electricity
_ _
(b)
__--==--""7'---"7"--- Purchased Resources ::.... ---.....----, - 1--7"""""" - Goods and Services __-..:=::-+-
Local Environmental Inputs
78M :>--"';";;';";"'-1
111
(c)
.;; ---,-""7'�_--- Purchased Resources __-....:.�
Local Environmental Inputs
Figure 2 2 . 1 5
1211120 ':>-':":";==; -I
Summary diagrams of four sys tems analyzed. showing the rela tive differences in intensity of development and spatial scales.
exported and resources purchased at Jari and by the national economy of PNG. At Jari, the loss of soils and fuelwood consumed at rates faster than they can be rebuilt amounts to 433 E18 sej/yr, or about 33% of the exported forestry products. In PNG, the export of for estry products and minerals (both processes are deplet ing storages faster than they can be replenished) represents about 2.6% of the economy's renewable emergy flow/yr and about 28% of the purchased
_-==-----/t.....,..-+...h..__117
Goods and Services
211
A l l flows E 1 8sej/yr (d)
resources and goods and services. Development of the hydroelectric potential at Tucurui results in the loss of sediments in the lower basin that is greater than the elec tricity produced. The shrimp fishery in the Sea of Cortez results in the export of national wealth totaling 498 E18 sej/yr, corresponding to about 68% of purchased resources and goods and services. Most of the development projects studied appear not to be ecologically or economically sound in the long run,
246
nor do they appear to lead to sustainable patterns of development. As long as wealth is exported and the corre sponding imported goods and services are less, the bal ance of emergy is negative. Where the costs of development exceed the emergy gained, as in Tucurui (if sediments are included), the net benefit to the economy is questionable. How long these relationships can last depends on the rate of extraction relative to the size of storages and productive capacity of the environment and the magnitude of the individual project relative to the larger economy. As long as projects are small relative to the larger economy, their sustainability is fostered by high net yields in other energy sources. Our suggestions for increasing sustainability and therefore economic well being in each of the regions studied can be summarized as follows: (1) minimize the export of raw resources in favor of using and upgrading them as much as possible within the national economy, (2) balance extraction with the local economy's potential to use resources internally, (3) balance extraction with the productive capacity of the landscape, and (4) population control.
National Economies A major challenge is the integration of local economies with the world economy. Our understanding of systems and hierarchies suggests such integration of national economies into the global economy is probably inevitable. Yet it is clear that exporting indigenous resources to the point of depletion and receiving in return lower-emergy resources from one's trading partner is neither beneficial nor sustainable. Developing countries such as Mexico, Thailand, and Papua New Guinea face a serious dilemma as they export raw resources and import goods and ser vices to support further extraction of fisheries, forest, or mineral products. Priming the "economic pump" from outside, which seems almost a necessity, has more often than not failed in fulfilling developing countries expecta tions. Our emergy analysis of development projects like those atJari or the shrimp industry in the Sea of Cortez revealed negative net emergy ratios that suggest they are, in effect, drains on the economy. So rather than boost the economy, as was hoped, they will decrease national eco nomic well-being in the long run. All too often, such eco nomic investments concentrate the affluence that results from extraction of resources in the hands of a small minority, and the population at large receives little from the sale. As a consequence, we have suggested policy alter natives that favor smaller-scale investments geared to the local economy's ability to absorb and process the extracted resources. In the long run, such development projects have a better chance of benefiting the national economy and, in turn, adding to the economic well-being of the local population. It is in this domain that we expect further research in macroeconomics and emergy analysis to be the most fruitful.
M. T. BROWN ET AL.
Emergy indices of development status and comparisons between regions lend some insight into the complexities of the policy questions facing developing nations. Com parisons of emergy indices between "developing" and "developed" economies are given in Table 22.18, along with the world economy as a whole. These categories are defined by both traditional economic indicators and emergy indicators, although like most macroscopic indica tors, they do not show many internal relationships that may be important. GNP is often used as an indicator of development status, where low GNP is indicative of devel oping regions (the Sea of Cortez and PNG), moderate GNP relates to moderately developed regions (Thailand and the Amazon), and countries with high GNP, like the United States, are considered developed economies. The use of GNP as a measure of development status considers only that portion of an economy that is within the monied economy. The ratio of the economic compo nent to environmental component of an economy (line 9 in Table 22.18) is a ratio of the purchased high-quality energy and goods and services used by an economy to its energy derived from indigenous renewable sources. When development status is viewed from this perspective, all the regions studied are below the world average and might be considered at the low end of development status, while the United States shows a ratio over twice the world average. The ratio of emergy to GNP dollars (line 11 in Table 22.18) is a measure of the buying power of the local cur rency and, when compared between regions, could be used as a measure of relative exchange rates. The Amazon and PNG have the highest emergy/GNP ratios of all regions included in this and related studies (Odum and Odum 1983) owing partly to a small developed economy and to the enormity of the contribution from indigenous sources of emergy. When a country with a low emergy/ GNP ratio purchases goods and services or lends money to countries like PNG, the purchasing (or lending) country receives an enormous advantage that is related to the dif ferences in their ratios. Figure 22.16 summarizes several indicators of develop ment status, relationships between currency and emergy flow, and relative buying power of PNG, Thailand, and the United States. The numbers are derived from Table 22.16 but have been reduced in proportion to renewable sources, so that the inputs from renewable sources are unity. Comparison between the two developing econo mies and the United States suggests their relative eco nomic positions, the most telling of which is their world purchasing power (the ratio of their emergy/GNP with that of the world emergy/GNP ratio). Both the United States and Thailand enjoy a positive ratio (1.8/1 and 1.3/ 1, respectively), and PNG exhibits a significant disadvan tage (0.08/1). In essence, PNG and other countries with world purchasing power ratios less than 1 support eco nomic activity of the world economy. Finally, the ratio of
247
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS Table 2 2 . 1 8
Comparative emergy indices of regions and nations U.S.A. (1983) Amazon Basin
Global
Index
Papua Sea of Cortez N. Guinea Thailand
15,000
940
918
7.9
46.2
74
2 Population (E6)
5,044
227
1,121
0.1
3.2
63
3 GNP (E9 $/yr)
5,000
3,305
214
12.4
2.5
43. 1
1 58,108
87,270
2,463
37.7
1 ,729.4
1 ,591.0
5 Renewable emergy (E20 sej/yr)
94,400
12,360
1 ,672
28.2
1 ,218.2
875.6
6 Nonrenewable emergy (E20 sej/yr)
63,708
52,860
791
9.5
51 1 .3
736.0
1 Land area ( 1 0 m2)
4 Emergy use (E20 sej/yr)
7 Ratio of renewable to total emergy use 8 Ratio of indigenous emergy to total emergy use 9 Ratio of economic component to an environmental component
0.1
0.7
0.7
0.7
0.6
0.7
1 .0
0.8
1 .0
0.7
7.1
0.7
0.2
0.2
1 .0
0.6
0.2
0.9
1 2.0
1.4
0.6
2.4
10 Ratio of exports:imports 11 Emergy:money ratio (E12 sej/GNP $)
3.2
2.6
1 1 .5
0.3
69.2
3.7
1 2 Emergy/capita (E15 sej/person . yr)
3.1
38.5
20.4
26.9
54.0
2.5
13 Emergy/unit area (E12 sej/m2 . yr)
0.1
1 .0
0.05
0.4
0.2
14 Population density (people/km2)
0.0
24.2
1 .8
69.3
85. 1
0.03 13.2
Nole: Global nonrenewable emergy is th e fossil fuel equivalent (1981 ) consumption.
exports
to
imports
shows
the
enormous
impression of the relative well-being of a country's
difference
inhabitants. A better measure is total emergy per capita.
between countries that enjoy positive emergy trade bal ances and those that export more values than they import.
•
In all, our analyses of the relative position of develop
Currency exchange rates do not reflect the real buy ing
ing economies to developed economies suggest that world
power
of
a
country's
currency
relative
to
another's.
A better measure is the ratio of emergy per dollar. When a country with a high emergy/dollar
economic policy should recognize the status of develop ing nations as providing much of the resources and ulti
ratio exports resources and then purchases goods
mate wealth upon which the developed nations survive.
with the money obtained from a country with a lower
Developing economies should begin to reverse current
ratio, more total value leaves the first country than is
thinking that export of resource wealth leads to national
received. Most undeveloped countries have
wealth and begin to develop internal economies slowly
high
emergy/ dollar ratios, and developed economies have
and efficiently to maximize internal emergy flows.
lower ones. Our calculations suggest that much of the debt now carried by the developing countries has
Conclusion
already been paid if the exchange ratios were calcu
The perspectives gained in the overview of these regions
lated using emergy instead of international currency
of the globe have resulted in several important recom
exchange rates.
mendations related to economic and development policy
•
that on the surface are counter to traditional economic
for finished products. The resulting net trade deficit
wisdom. These are summarized as follows: •
•
drains the resource-exporting economy in favor of the importing economy.
A resource's contribution to an economy is often inverse to its dollar value.
Raw resources should not be exported in exchange
•
Sustainable development projects are usually scaled
GNP per capita as a measure of standard of living does
such that the ratio of energies derived from economic
not include important contributions from the unmo
inputs to energies derived from environmental inputs
nied sectors of an economy and provides a false
is intermediate, the spatial scale is intermediate, and
M. T. BROWN ET AL.
248
---
(54%)
Emergy/DoIlar
=
2.0E 1 2sej/$
Inveslment Ratio
:0
7/ 1
Total Emergy/Purchased
:0
8/7
World Purchasing Power
:0
3.B/aO
1. 1 / 1
Exports/Imports
=
4.3/7
=
=
1.8/ 1
.6/ 1
=
Thailand r-----:�--.."...-...,(
- ----
0. 1
-- .
Emergy/Doliar ,. 3.7EI 2sej/$ Investment Ratio
=
.4/ 1
Total Emergy/PlJ'chased ,. 1.4/.4
3.5/ 1
=
World PlJ'chasing Power
=
3.B/3.7
Exportsllrnports
=
.35/.4
=
=
1.311
.88/1
P.N.G. .04__
� ....: .._ :.. -
-
Figure 22. 1 6
- -.,.. 0.0 1
=
48E 1 2sel /$
=
.0411
Total Emergy/PlJ'chased
=
1.041.04
World Purchasing Power
=
3.8148
=
.08/ 1
Exportsllmports
=
.52/.04
=
131 1
=
26/ 1
Comparative summary of indicators of relative emergy and currency flows, devel opment status, and relative purchasing power of the United States (U.S.A.), Thai land, and Papua New Guinea (p.N.G. ) . Emergy flows are sejlyr. and dollar flows are dollars/yr.
the temporal scale (the speed at which the project is done) is intermediate as well. •
Emergy/Doliar Investment Ratio
For a development project that involves export to have a positive benefit to a local economy and not drain it of resources for export, the investment of eco nomically derived energy should be equal to that characteristic of the economy as a whole.
In conclusion, we do not presume to have all the answers to the difficult questions humanity faces in its quest for sustainable development of natural resources; but we do feel emergy analysis has promise as a means of focusing attention on the real issue of resource use and exploitation and of providing a necessary insight toward the making of purposeful public policy decisions.
Determination of resource value according to price or willingness to pay and determining a nation's wealth based on the flow of currency do not adequately measure either. A resource's contribution to an economy is inde pendent of its price, and flow of currency, although pro viding an index of production, accounts only for human services in most cases. A better perspective of resource value and material wealth emerges if energy is used as the foundation of value and transformed to emergy as a mea sure of equivalent work potential.
Notes 1.
Emergy is a relatively new concept that quantifies the energy previously required to produce a given product
DEVELOPING AN INTERFACE OF ECOLOGY AND ECONOMICS or drive a given process. Sometimes referred to as energy memory (Scienceman 1987), emergy is expressed in err9 0ules of the same type (solar emjoules; sej ) to differentiate it from energy expressed in joules.
2.
Environmental loading is used in this context analo gous to a load on an electrical circuit; the greater the load, the more current is drawn; hence, the greater the "load" on the environment, the more resources and services are drained from it.
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