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EMERGY SYNTHESIS 3: Theory and Applications of the Emergy Methodology

Proceedings from the Third Biennial Emergy Conference,

Gainesville, Florida

Edited by Mark T. Brown

University of Florida Gainesville, Florida

Managing Editor

Eliana Bardi University of Florida,

Gainesville, Florida

Associate Editors Daniel E. Campbell

US EPA Narragansett, Rhode Island

Vito Comar State University of Mato Grosso do Sul

Dourados, Brazil

Shu-Li Haung National Taipei University

Taipei, Taiwan

Torbjorn Rydberg Centre for Sustainable Agriculture

Uppsala, Sweden

David Tilley University of Maryland College Park, Maryland

Sergio Ulgiati University of Siena

Siena, Italy

November 2005

The Center for Environmental Policy Department of Environmental Engineering Sciences

University of Florida Gainesville, FL

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21

Emergy Synthesis of Socio-Economic Metabolism

Chun-Lin Lee and Shu-Li Huang

ABSTRACT

Recently, awareness of global climate change and limited natural resources has encouraged research about the metabolism of socio-economic systems. The “Industrial Transformation” project of the International Human Dimensions Programme (IHDP) has identified socio-economic metabolism as an important component of systems analysis. After the World Resources Institute (WRI, 1997 and 2000) and EuroStat (2001) promoted the Material Flows Accounts (MFA), many nations around the world adopted the MFA as a common foundation of comparison. However, there are still many unresolved issues about the MFA, such as its units, aggregation, and omitted energy flows. Therefore, this article can be separated into two parts. First, methodological issues about the MFA will be explored through a review of the literature. Second, an attempt will be made to apply emergy synthesis to evaluate the socio-economic metabolism of Taiwan. Those results will be compared with the results of MFA, and methodological issues will be discussed. We find that MFA incompletely describe a socio-economic system because they undervalue the role of energy, a critical concern for Taiwan given its increasing dependence on energy use. In Taiwan’s experience, some MFA indicators give very different results from emergy indicators and there are some situations, like transformation of resource consumption and material requirement change, that can’t be discovered from just a material flow point of view. In addition, focusing on weights, as MFA does, ignores differences between qualities of material flows. INTRODUCTION

Recently, awareness of global climate change and limited natural resources has encouraged research into the interaction between human systems and the natural environment. After many interdisciplinary experiences, several concepts from ecology have been adopted by the social sciences. The study of the metabolism of socio-economic systems has become an important field in interdisciplinary research.

Purves et al. (1992) pointed out that each cell carries out thousands of biochemical reactions to sustain the processes of life and the sum of all biological reactions constitutes metabolism. REQM (Residuals and Environmental Quality Management) defines metabolism as the amount of chemical reactions in an organism. However, the definitions above are both from a viewpoint of cells or organisms. Wolman (1965) utilizes the concept of metabolism to analyze the influence between the urban and non-urban environment. H.T. Odum and E.P. Odum (1973) apply metabolism to discuss every biological level from the cell to organism to whole ecosystem. H.T. Odum and E.C. Odum (1982) and H.T. Odum (1996) describe the flows of energy and matter within economic and ecological systems, as a way to quantify the driving forces of a system’s metabolism. Beyond that, the application of metabolism to socio-economic systems is now being discussed extensively.

Fischer-Kowalski (1998) recently reviewed research on the application of metabolism to the social sciences from 1860 to 1998 and she feels that, after long debate, consensus is emerging for a

Chapter 21. Emergy Synthesis of Socio-Economic…

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theoretically stringent approach. The study of socio-economic metabolism can be separated into two viewpoints about systems. The first regards socio-economic systems as the core of analysis and emphasizes input and output of the system. This approach has a social science emphasis, often applied to the metabolism of countries, with methods such as Material Flows Accounts (MFA). The second views socio-economic systems as a part of a larger system (i.e. human-ecosystem from Abel and Stepp, 2003) and this approach emphasizes the environment and interactions between the two systems, as in studies of socio-economic metabolism using emergy analysis.

The “Industrial Transformation” project of the International Human Dimensions Programme (IHDP) has identified socio-economic metabolism as an important variety of systems analysis. After the World Resources Institute (WRI, 2000) and EuroStat (2001) promoted the MFA, many nations around the world adopted it as a common method of comparison. However, there are still many unresolved issues about the MFA, such as its units, aggregation techniques, and omitted energy flows. Even though Haberl et al. (2004) and IFF Social Ecology incorporate material and energy flow accounting (MEFA), which includes energy flows in the accounting system, the units and aggregation issues remain. Emergy accounting (Odum, 1996) on the other hand, has been rejected by classical and neoclassical economists and has not yet been applied to the comparison of socio-economic metabolism for countries around the world. However, we believe that emergy synthesis can solve many of the problems of MFA as it is applied to socio-economic metabolism.

Therefore, this article will be divided into two sections. First, methodological issues confronting the MFA will be explored in the literature review1. Second, an attempt will be made to apply emergy to analysis of the socio-economic metabolism of Taiwan and compare those results with MFA results to argue our position.

MFA – CURRENT STATUS AND METHODOLOGICAL ISSUES

Early material flow analyses focused on identifying material flows in socio-economic

metabolism. In order to provide a more convenient tool for summarizing the sustainability of countries, the complex process of material flow analysis has been simplified to material flow accounts (MFA). At this time, most research on socio-economic metabolism addresses sustainable development (Haberl, 2001). MFA’s have focused on creating sustainable development indicators. Material Flow Accounts (MFA)

MFA is patterned after traditional accounting practices by providing an aggregate overview

by weight of annual material inputs and outputs of an economy, including inputs from a country’s natural environment, outputs to the environment, and trade accounting for imports and exports in terms of physical quantities traded. MFA constitutes a basis from which a variety of material flow based indicators can be derived. Wernick and Ausubel (1995) utilize MFA to evaluate socio-economic metabolism. WRI (2000) adopted the structure and estimated “The Weight of Nations”, which considered the loss during the process of extracting, production, and transit. EuroStat (2001) established a standard procedure of MFA, which used similar structure to WRI and defined the loss as hidden flows and indirect flows, in “Economy-wide material flow accounts and derived indicators: A methodological guide” (Figure 1).

Importantly, MFA includes hidden flows of domestic origin (domestic unused extraction) and indirect flows (upstream material flows associated with imports) to account for material flows that would be ignored in other analyses of socio-economic systems. A multi-level material balance scheme

1 In order to explore the influence of omitted energy flows and the roles of energy flows in Taiwan, we adopt MFA

instead of MEFA as the compared target with emergy synthesis.


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Main categories

of flows

Classification

of materials

Data gathering

& Evaluation

The material

balance

Indicators

analysis

Figure 1. MFA analysis construction (source: EuroStat, 2001). Table 1. Composite MFA with derived resource use indicators.

INPUTS (origin) OUTPUTS (destination) Domestic extraction

Fossil fuels (coal, oil…) Minerals (ores, sand…) Biomass (timber, cereals…)

Imports

Emissions and wastes Emission to air Waste land-filled Emission to water

Dissipative use of products and losses DMI – direct material inputs Unused domestic extraction

From mining/quarrying From biomass harvest Soil excavation

DPO - Domestic processed output to nature Disposal of unused domestic extraction

From mining/quarrying From biomass harvest Soil excavation

TMI - Total material input TDO - Total Domestic Output to nature Exports

Indirect flows associated to imports TMO - Total Material Output

Net additions to stock TMR - Total Material Requirement

Indirect flows associated to exports Source: EuroStat (2001) has been designed. Finally, MFA also provides some typical indicators constructed using specific material categories that enable comparison between nations. Table 1 and Figure 2 show the main material flow categories supporting a national economy. Methodological Issues of MFA

Currently, MFA has become an important tool for discussing the problem of sustainable development, adopted for use by large-scale international panels of researchers (Fischer-Kowalski and Huttler, 1998). There remain, however, some unresolved issues about MFA and these issues will be discussed below and analyzed in comparison to an emergy synthesis of Taiwan’s socio-economic metabolism.

Omitted Energy Flows

Ostwald (1909), a Nobel Prize chemist, was the first to study socio-economic systems from an energy viewpoint. Odum (1971, 1983) added autocatalytic designs, based on general systems theory, that consumers could feedback small amounts of energy to get more energy from a system. Martinez-Alier and Schlupmann (1987) dealt with the study of energy flows and the analysis of the economy from the ecological point of view. Adams (1988) also considered energy to be a trigger of human civilization in which a society gets more energy after using some energy to pull the trigger (another


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Imports

Domestic Extraction:Fossil fuelsMineralsBiomass

Unused Domesticextraction

Exports

Indirect flowsassociated toexports

Input Economy OutputMaterial accumulation(net addition to stock)

Material throughput(per year)

Indirect flowsassociated toimports

Unused Domesticextraction

To nature:Emissions to airWaste landfillEmissions to water

Recycling

Figure 2. Main aggregated material flow categories supporting a national economy (source: EuroStat, 2001). example of autocatalytic design). Giampietro et al. (1992) assessed the amount of power used to alter ecosystems during the process of socio-economic metabolism. Material flows and energy flows, therefore, should be considered as two different aspects of socio-economic metabolism. Only when materials and energy are both considered, can socio-economic metabolism be adequately evaluated (Haberl, 2001). However, most current research on socio-economic metabolism, like MFA, ignores energy flows because of the difficulty of comparing materials and energy with the same units. Energy flows are omitted in the standard evaluation of MFA, and indeed this is its most contentious issue. In principle we therefore know that MFA is an incomplete methodology by its omission of energy flows, but the actual impact of omitting energy flows in a real world case has seldom been discussed. We will explore these shortcomings with an emergy synthesis of Taiwan’s socio-economic metabolism. System Boundary

An MFA of socio-economic metabolism focuses on the flows between economy and environment, and only flows that cross the system boundary are counted. For this reason, flows within the economy are not accounted for in MFA and the interactions between elements are ignored. However, the relations between a socio-economic system and its natural environment are very complex and difficult to separate. MFA attempts to simplify the flows as inputs and outputs through the socio-economic system boundary. However, this omits countless flows and interactions within and between the natural environment and socio-economic system. Units

Material flows are measured in mass units. This common practice presents the following problems:

(1) Aggregation of materials It is necessary to aggregate material flows for an overview of a socio-economic system, but

during the process of aggregation the material characteristics, quantity and quality are ignored. The quantity of material flows are known, but the identity of the materials is lost, with a subsequently dramatic effect on MFA policy indicators, i.e., heavy materials of some kind will drive the direction of policy.


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(2) System elements MFA inputs and outputs are chosen by weight, and it is therefore very likely that critical

materials associated with a socio-economic system will be omitted from analysis because their weights do not reach the threshold. EMERGY SYNTHESIS OF TAIWAN’S SOCIO-ECONOMIC METABOLISM

We will now use an emergy synthesis of Taiwan’s socio-economic metabolism. We will then

compare and discuss MFA and emergy indicators.

Taiwan’s Ecological, Economic and Social System

Taiwan’s socio-economic system is represented by means of energy systems symbols in Figure 3. The diagram explicitly incorporates the socio-economic system, natural land, agricultural land, renewable resources, imports and exports. The resource elements in the system are selected on the basis of a 95% threshold (by weight) from each material category in Taiwan’s MFA by Lin (2000), and a 95% threshold (in emergy units) from Taiwan’s emergy synthesis table in Huang and Odum (1991) to identify important items of resource flows in Taiwan’s ecological, economic and social system. Emergy Synthesis of Taiwan’s Socio-Economic system

A synthesis of Taiwan’s emergy flows from 1981 to 2001 is provided in Table 2. We find that the use of the renewable resources of water and hydroelectricity is increasing. Non-renewable domestic extraction of marble and electricity use are also rising, as well as the demand for many kinds of energy and mineral imports from foreign countries, such as coal, petroleum, crude oil and industrial minerals. Among exports, petroleum and metal products have risen. For a macro viewpoint of Taiwan’s socio-economic metabolism, we aggregate the resource use in Table 3, which contains material flows, energy flows, and eco-economic emergy flows, into the overview diagram of resource use of Taiwan in Figure 4.

Taiwan’s socio-economic system underwent a transition from an agricultural society to an industrial society during the period 1981 to 2001. In Table 3 and Figure 4, we can see that during this industrial transition, Taiwan’s DMRs (domestic renewable materials), such as rice, sugarcane, vegetables, fruits, etc., have recently become stable. However, because Taiwan is an island, which is not rich in some natural resources, the storages of DMNR (domestic non-renewable materials) have diminished and have needed to be supplemented by imports TMI (imported material flows). Nevertheless, due to the requirements of the socio-economic system, the consumption of IME (imported energy) and F (imported fuels and minerals) has increased substantially with industrial development. A rising U (total emergy used) follows the same trend as resources use. TMR (total material requirement), on the other hand, has stabilized in recent years because the industrial society has become a service industry society that uses fewer materials.

The total material requirement (TMR) is stable, indicating that the material use of Taiwan has not changed significantly from 1991 to 2001. However, EXM (exported material flows) increased rapidly during the same period, as has imported energy. This is not reasonable from the material balance standpoint of MFA, but is understandable if Taiwan’s socio-economic system is conceived as driven by energy use. Energy inputs are the trigger of Taiwan’s development. It appears that some kind of technical progress or industrial transformation has taken place in Taiwan in which the same amount of materials is being used to export more goods via increased energy inputs.

Natural Land

Ocean

Cultivated Land

Socio-Economic Land

Agricultural Land

Oil seeds & flours

Iron & steel

productsCereals & prep.

Petrolem gas

Woods & prep.

Petrolem products

Coal

P

P

P

P

P

P

P

Iron ore and

concentrat

P

Marble

Sand & gravel

Sugar- cane

Vege- tables

Lime- stone

Waste landfilled

Money

Emission to air

Buildings

Others

Humans

Emission to water

Crude OilP

Livestock products

P Industrial minerals

P

Slag waste

FruitRice

Transport infrastructure

Flint

Ballast

ShinglClinkers

Portland Cement

Livestock production

Fishery production

Fish & Mollusca

Woods & their prep.

Indirect flows assoication to

imports

Petrolem products

Metal products

Indirect flows assoication to

exports

Unused domestic extraction

Sun

Wind (kinetic)

Rain

Figure 3. Taiwan’s socio-economic system.

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Chapter 21. Em

ergy Synthesis of Socio-economic...


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Table 2. Taiwan’s emergy analysis table 1981~2001.

Resources Item 1981 1986 1991 1996 2001 Solar Emergy (1020 sej)

Renewable Resources

1. Sun; J 2.72 2.72 2.72 2.72 2.722. Wind(kinetic); J 212.19 212.19 212.19 212.19 212.19 3. Typhoons; J 21.34 17.07 12.80 12.80 21.34 4. Rain(geopotential); J 54.26 51.18 43.05 57.27 50.26 5. Rain(chemical); J 96.02 90.56 76.18 101.33 88.93 6. Tide; J 0.64 0.64 0.64 0.64 0.647. Geologic uplift; J 33.84 33.84 33.84 33.84 33.84 8. Wood consumption; J 2.31 2.19 0.36 0.22 0.19 9. Hydroelectricity; J 273.43 424.22 314.60 517.28 507.02

10. Water used; J 45.78 65.74 77.94 89.24 93.17 11. Sugar-cane; g 32.09 22.87 17.28 15.96 8.3112. Rice; g 104.50 86.85 80.02 69.40 61.44 13. Fruits; g 106.44 113.94 152.19 151.45 159.2114. Vegetables; g 369.17 394.11 360.85 385.48 383.6215. Livestock production; g 0.00 327.11 442.66 313.68 476.4716. Fishery production; g 649.02 779.24 937.32 882.50 937.50

Non-renewable Resources

17. Sand and gravel; g 0.00 0.00 0.01 0.02 0.0218. Electricity used; J 214.71 308.54 464.19 637.23 816.5219. Nuclear electricity; J 58.33 148.13 194.24 208.32 212.1220. Marble; g 4.73 5.64 6.51 9.63 11.2621. Limestone; g 132.21 124.54 153.47 113.31 49.0122. Erosion; T 147.74 147.74 147.74 147.74 147.74

Import 23. Coal; J 60.49 128.32 426.14 717.59 1136.0824. Petroleum gas; J 5.77 13.86 60.00 82.28 137.3825. Crude oil; J 418.66 418.17 545.68 813.67 916.41 26. Petroleum products; J 62.83 48.56 139.68 183.10 228.16 27. Marble & Granite; g 0.00 0.03 0.31 0.72 1.1628. Woods & their prep.; g 31.40 26.09 31.73 24.97 19.3829. Iron ore and concentrate; g 14.60 32.42 51.02 60.95 94.2130. Industrial minerals; g 14.37 14.46 34.98 42.33 79.1931. Iron & steel products; g 40.57 89.62 67.03 59.48 94.6332. Cereals & their prep.; g 312.46 357.93 481.74 527.69 473.0433. Oil seeds & flours; g 0.00 131.18 157.25 195.72 177.8134. Livestock products; g 0.00 125.04 145.18 201.80 180.1535. Goods & services; $ 476.19 598.91 1522.62 2437.97 2520.34

Export

36. Sand and gravel; g 0.00 0.00 0.00 0.00 0.00 37. Petroleum products; J 36.32 70.96 72.95 168.64 230.62 38. Woods & their prep.; g 0.24 0.29 0.26 1.01 0.6539. Flint, ballast & shingle; g 0.00 0.00 4.70 3.04 5.60 40. Fruits & prep.; g 16.83 12.34 10.11 7.72 5.58 41. Cereals & prep.; g 6.56 13.90 13.23 9.38 14.48 42. Vegetables & prep.; g 60.43 70.21 34.83 19.24 10.77 43. Metal products; g 10.71 182.95 94.91 122.84 288.4344. Slag waste; g 0.76 26.05 16.57 73.41 55.0345. Portland Cement; g 245.31 277.92 262.10 320.06 1003.36 46. Cement clinkers; g 16.66 28.80 40.46 261.42 98.17 47. Fishes & their prep.; g 114.22 134.29 225.57 256.95 325.4248. Mollusca &their prep.; g 0.00 53.96 39.20 21.08 32.4249. Hides, skins & their prep.; g 3.99 37.55 54.73 143.94 118.0250. Goods & services; $ 495.59 912.42 1683.59 2624.89 2835.56

Waste produced51. Waste water 27.47 39.44 46.77 53.55 55.9052. Solid waste 270.63 386.88 549.88 661.81 551.07

Note: The normal text items come from Huang and Odum (1991), bold items come from Lin (2000) and the underlined items come from both of them.


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Table 3. Aggregate of resource flows (The categories and structure of material flow items in Table 2 come from MFA. The bold numbers mean annual flow quantity by kilogram).

Solar Emergy (1020 sej)Code Description 1981 1986 1991 1996 2001

TMR Total material requirement(DM + TMI) 1813.88 2633.27 3119.92 3055.31 3206.58 = Domestic material flows + Imported material flows 62.07 71.65 98.25 140.05 135.67 E9 kg

TMI Imported material flows(TMInr + TMIr) 413.40 776.78 969.23 1113.65 1119.57 = Imported non-renewable materials 16.40 24.22 32.13 35.14 45.62 E9 kg + Imported renewable materials

TMInr Imported non-renewable materials 69.54 136.54 153.34 163.47 269.19 = Marble & Granite + Industrial minerals 6.38 12.15 16.86 19.67 32.27 E9 kg + Iron ore and concentrate + Iron & steel products

TMIr Imported renewable materials 343.86 640.24 815.89 950.18 850.38 = Woods & their prep. + Cereals & their prep. 10.03 12.07 15.27 15.47 13.36 E9 kg + Oil seeds & flours + Livestock products

DM Domestic material flows(DMnr + DMr) 1400.48 1856.49 2150.69 1941.66 2087.01 = Domestic non-renewable materials 45.67 47.44 66.13 104.91 90.05 E9 kg + Domestic renewable materials

DMnr Domestic non-renewable materials 136.94 130.18 159.99 122.96 60.29 = Sand and gravel + Limestone + Marble 28.89 31.62 51.19 91.03 77.49 E9 kg

DMr Domestic renewable materials = Rice + Sugar-cane + Vegetables + Fruits 1263.54 1726.30 1990.70 1818.69 2026.73 + Wood consumption + Livestock production 16.77 15.82 14.93 13.88 12.56 E9 kg + Fishery production

EXM Exported material flows(EXMnr + EXMr) 512.03 909.20 869.61 1408.73 2188.56 = Exported non-renewable materials 3.20 5.63 5.64 9.91 14.17 E9 kg + Exported renewable materials

EXMnr Exported non-renewable materials 309.77 586.68 491.68 949.41 1681.22 = Slag waste + Sand and gravel + Portland Cement 2.15 4.33 4.56 8.83 13.09 E9 kg + Flint, ballast & shingle + Cement clinkers + + Petrolem products + Metal products

EXMr Exported renewable materials 202.26 322.52 377.92 459.32 507.34= Cereals & prep. + Vegetables & prep. + Fruits & prep 1.05 1.29 1.08 1.09 1.08 E9 kg + Hides, skins & their prep. + Fishes & their prep. + Mollusca & their prep. + Woods & their prep.

M Total material flows(TMR + EXM) 2325.91 3542.47 3989.52 4464.03 5395.14 = Total material requirement + Exported material flows 65.27 77.28 103.89 149.96 149.84 E9 kg

TER Total energy requirement(DEI + IME) 1092.34 1394.10 1893.17 2735.07 3349.99 = Domestic energy inputs + Imported energy

DEI Domestic energy inputs 544.59 785.18 721.66 938.43 931.96 = Renewable resources + Hydroelectricity + Nuclear electricity

ELEC Electricity used 214.71 572.35 508.83 725.60 719.13

IME Imported energy 547.75 608.92 1171.50 1796.65 2418.03 = Coal + Petroleum gas + Crude oil 24.71 30.36 66.09 104.45 148.34 E9 kg + Petrolem products

EXE Exported energy 0.00 0.00 0.00 0.00 0.00

E Total energy flows(TER + EXE) 1092.34 1394.10 1893.17 2735.07 3349.99 = Total energy requirement + Exported energy

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R Renewable resources in Taiwan 212.83 212.83 212.83 212.83 212.83 = Wind(kinetic) + Tide

N Non-renewable resources in Taiwan 614.13 848.09 816.20 996.08 926.98

N0 Primary resource 145.43 145.56 147.38 147.52 147.56 = Erosion - Wood consumptionN1 Concentrated used resource 468.70 702.53 668.82 848.56 779.42 = Hydroelectricity + Nuclear electricity + Sand and gravel + Limestone + MarbleN2 Direct export 0.00 0.00 4.70 3.04 5.60 = Sand and gravel + Flint, ballast & shingle

F Imported fuels and minerals 617.29 745.46 1324.84 1960.12 2687.22 = Coal + Petrolem gas + Crude oil + Petrolem products + Industrial minerals + Iron ore and concertrate + Marble & Granite + Iron & steel products

G Imported good and services 343.86 640.24 815.89 950.18 850.38 = Woods & their prep. + Cereals & their prep. + + Oil seeds & flours + Livestock products +

U Total emergy used 1844.54 2566.76 3447.75 4530.26 5074.39 = R+N0+N1+G+F+IMS

IMS Imported services 56.43 120.14 277.99 411.05 396.99

EXS Exported services 47.92 123.19 175.23 329.27 402.73

W Waste produced 298.10 426.33 596.64 715.35 606.97

Pop Population 1.81E+07 1.95E+07 2.06E+07 2.15E+07 2.24E+07 per

X GDP 4.68E+10 8.03E+10 1.83E+11 2.79E+11 2.72E+11 US$

P2 Emergy / Money (World) 1.98E+12 1.98E+12 1.98E+12 1.98E+12 1.98E+12 sej/$

P1 Emergy / Money (Taiwan) = Total emergy used / GDP

(R+N0+N1+G+F+IMS) / GDP = 3.94E+12 3.20E+12 1.88E+12 1.62E+12 1.87E+12 sej/$

Domestic Resources UseR+N0+N1= 826.96 1060.92 1029.03 1208.91 1139.81

Imported Goods & ServicesF+G+IMS= 1017.58 1505.84 2418.72 3321.35 3934.59

Exported Goods & ServicesEXM+EXS= 559.95 1032.39 1044.84 1738.00 2591.29

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DISCUSSION

After initial discussion of Taiwan’s socio-economic metabolism, some comparative analyses with indicators will be made to argue our position regarding MFA. In Table 4 we calculate some indicators and then use them in Figures 5 through 7 to compare MFA and emergy viewpoints.

The Relative Contribution of Material Flows

In Figure 5, the ratio of total material requirements to total emergy used has decreased over time, which indicates that the consumption of material flows plays a less important role in Taiwan’s socio-economic metabolism. Moreover, the system imports more materials from foreign countries as seen in the increase of the ratio of imported material flows to total material requirements. However, despite the increase of imported material flows, the ratio of imported material flows to total imported


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emergy is decreasing; or in other words, the importance of imported material flows is diminishing among all imported resources (material flows, energy flows and services). Finally, the ratio of exported material flows to total material flows is increasing, which reveals the export-oriented policies of Taiwan’s socio-economy. The Dependency on Material Flows and Energy Flows The dependency on materials and energy is an important issue in the paper. In Figure 6, the ratio of total material requirements to total energy requirements was over 1.0 from 1981 to 1996, which indicates the important role that material flows played at the time. However, that ratio has decreased to 0.96 in 2001 indicating that energy is starting to play an ever more important role in Taiwan’s socio-economic system. Taiwan is facing a transformation of resource consumption in which more energy

TMIr TMInr

R Productive Area

N0

IME

GNP

R

N1

N2

Natural Area

G F

Socio-Economic Area

DMr

EXM

DMnr

IMS

EXSW

Exported Goods & Services

(EXM, EXS)W

Imported Goods & Services (F, G, IMS)

Domestic Resources Use

(R,N0,N1)Socio-Economic

System

850.38

269.19 2418.03

2687.22

396.992188.56

402.73

606.97212.832026.73

60.29

147.56

5.60779.42

Unit: E20 sej

U = 5074.39

TMR = 3206.58

1139.81

3934.59

606.97

2591.29

Unit: E20 sej

2.79E+11 $

Taiwan Eco-economic System

Taiwan Eco-economic System

GDP

Figure 4. Aggregate diagram of resource use in 2001.


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Table 4. Indicators analysis table.

Indicators Equation 1981 1986 1991 1996 2001

(1) Ratio of total material requirements to total emergy used = TMR / U 0.98 1.03 0.90 0.67 0.63(2) Ratio of imported material flows to total material requirements = TMI / TMR 0.23 0.29 0.31 0.36 0.35(3) Ratio of imported material flows to total imported emergy

= TMI / (TMI+IME+IMS) 0.41 0.52 0.40 0.34 0.28

(4) Ratio of exported material flows to total material flows = EXM / M 0.22 0.26 0.22 0.32 0.41(5) Ratio of total material requirements to total energy requirements = TMR / TER 1.66 1.89 1.65 1.12 0.96(6) Ratio of imported material flows to imported energy = TMI / IME 0.75 1.28 0.83 0.62 0.46(7) Per GDP total material requirements (kg) = TMR(kg) / GDP 1.33 0.89 0.54 0.50 0.50(8) Per GDP total material requirements (sej) = TMR(sej) / GDP 3.87E+12 3.28E+12 1.70E+12 1.10E+12 1.18E+12(9) Per capita total material requirements (kg) = TMR(kg) / pop 3,422 3,683 4,768 6,506 6,055(10) Per capita total material requirements (sej) = TMR(sej) / pop 1.00E+16 1.35E+16 1.51E+16 1.42E+16 1.43E+16

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1981 1986 1991 1996 2001 Year

Ratio (1) Ratio of total materialrequirements to total emergy used(2) Ratio of imported material flowsto total material requirements(3) Ratio of imported material flowsto total imported emergy(4) Ratio of exported material flowsto total material flows

Figure 5. Indicators analysis A. and fewer materials are used. The MFA, which does not consider these energy flows, does not recognize this phenomenon. Another important observation related to material and energy is that the ratio of imported material flows to imported energy is less than 1.0 from 1991 to 2001. This change in the ratio indicates that dependency on imported energy is increasing, following the trend of dependency on total energy requirements. Weight vs. Emergy

The use of weight, or mass, for evaluating socio-economic metabolism is not only the most common but also the most disputed feature of the MFA procedure. Characteristics of the materials are


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Ratio(5) Ratio of total material requirementsto total energy requirements

(6) Ratio of imported material flows toimported energy

Figure 6. Indicators analysis B. ignored during the process of material aggregation by weight. In this section we compare mass and emergy to determine the characteristics that are omitted by the socio-economic metabolism approach

The measure of total material requirements per unit of economic product (TMR/GDP) is a familiar indicator of progress in production techniques in MFA. In Figure 7, mass-based TMR/GDP for Taiwan decrease from 1981 to 1991 and are stable from 1991 to 2001, which suggests that the production efficiency of industries in Taiwan has improved from 1981 to 1991 and has not changed significantly from 1991 to 2001. In contrast, emergy-based TMR/GDP reveal that Taiwan’s industries use less emergy per unit of GDP and can utilize more raw materials with lower emergy cost because of technical progress. This is evidence that Taiwan’s industries are evolving from traditional processing industries to high-tech industries, which can process more raw materials.

Furthermore, mass-based TMR/capita shows that the people in Taiwan consumed increasing amounts of materials from 1981 to 1996 and then decreases from 1996 to 2001. Comparatively, emergy-based TMR/capita began to decrease in 1991. The reason for the increase of mass-based TMR/capita and decrease of emergy-based TMR/capita from 1991 to 1996 is that Taiwan’s socio-economic system consumed significant amounts of materials from lower in the energy hierarchy (e.g. sand and gravel).

CONCLUSION

In the methodological comparison of MFA and emergy synthesis, we find that MFA includes hidden flows of domestic origin (domestic unused extraction) and indirect flows (upstream material flows associated with imports) in accounting for the material flows of a socio-economic system, and it does work to describe a system more closely approximating the real world.

However, because the hidden flows and indirect flows are included in estimates of total amount, it is not easy to recognize where the flows go? Due to the lack of information on the items of materials of hidden and indirect flows, we did not calculate the emergy of hidden flows and indirect flows in this paper. Furthermore, the material categories in MFA’s socio-economic system do not contain energy flows, electricity used, and services, which play increasingly important roles in Taiwan’s socio-economic metabolism. Given the trend of resource use toward fewer materials and more energy, the fact that energy flows, electricity use, and services are omitted leads to bias in the evaluation of socio-economic metabolism.


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(7) Per GDP total material requirements (kg)

(8) Per GDP total material requirements (sej)*E+12

(9) Per capita total material requirements (kg)*E+3

(10) Per capita total material requirements (sej)*E+16

Figure 7. Indicators analysis C.

The second goal of this paper was to illustrate, for the case of Taiwan, some limitations of

MFA analysis, and to demonstrate the usefulness of an emergy synthesis of socio-economic metabolism. After completing an emergy analysis of Taiwan’s socio-economic metabolism and comparing indicators calculated from mass against similar indicators calculated with emergy, we found that MFA could not identify the essential fact of Taiwan’s increasing dependence on energy use. We contend that the MFA will not adequately describe socio-economic metabolism without increased attention to energy flows. In the comparison of MFA and emergy synthesis indicators for Taiwan, MFA indicators apparently do not recognize changes in types of materials consumed; for instance, while the industrial economy of Taiwan was transformed to rely more heavily on materials belonging to lower levels of the energy hierarchy, this change did not translate into a change in the MFA indicator values. This was largely because the use of mass ignores energy quality differences among materials. In addition, neither MFA nor emergy synthesis identified the transition from industrial society to service economy because domestic services are ignored. In summary, we feel that emergy synthesis allows a deeper understanding of Taiwan’s socio-economic metabolism than MFA. ACKNOWLEDGMENT

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