Low Carbon Economy, 2011, 2, 32-40
doi:10.4236/lce.2011.21006 Published Online March 2011 (http://www.SciRP.org/journal/lce)
Analysis of Material Metabolism of Eco-Economic
System in Chongqing Based on the Emergy Theory
Gao Xue-song1,2, Luo Xiao-jiao3, Deng Liang-ji1,2, Z eng Min1
1College of Resourses and Environment, Sichuan Agricultural University, Ya’an, China; 2.Center for Rural Development Research,
Ya’an, China; 3College of Architecture, Southwest Jiaotong University, Chengdu, China.
Received December 3rd, 2010; revised December 29th, 2010; accepted January 10th, 2011.
ABSTRACT
Based on the emergy theory proposed by H. T. Odum, the material metabolism of eco-economic system in Chongqing
during 2002 ~ 2007 is analyzed. The resu l ts s h ow that 1) the total available emergy in Chongqing is quite abundant and
the economy is relatively more developed; the total metabolic output in Chongqing in 2007 was approx imately 70% of
its total metabolic input and both are increased, with an annual growth of 7.07% and 14.3% respectively; 2) the de-
creasing trend of most emergy efficiency indexes including system emergy self-sufficiency rate, emergy waste rate and
emergy yield rate sho w that eco-economic system in Chongqing is still a resou rce consumption one, that the economic
development mainly relies on local non-renewable resources, that the pressure of urban development on the environ-
ment keeps increasing and that the urban recycling capacity is yet to be improved; 3) the metabolic efficiency and
metabolic intensity of the system are both increased, with an annual growth rate of 7.34% and 8.41% respectively; and
4) the environmental impact index of metabolism drops slowly, while the environmental loading ratio is large? fluctu-
ating between 16.8 and 13.7. The prerequisite of achieving sound operation of the metabolic system in Chongqing lies
in the regulatio n and control of the intera ctive relationship between metabolic fluxes so as to promote th e coordinated
symbiosis of urban metab ol i c emer gy fl uxes .
Keywords: Emergy Theory, Material Metabolism, Metabolic Flux, Metabolic Efficiency, Chongqing Municipality
1. Introduction
China’s rapid industrialization and urbanization have
aggravated the demand for natural resources and the en-
vironmental pollution. This extensive resource metabo-
lism mode has increasingly obviously restricted the fur-
ther development of the regional economy, and evalua-
tion of the sustainable development of regional economy
is urgently needed. The material metabolism analysis is
to expound the d emand of regional eco-economic system
for resources and the pressure of waste emission on the
system, based on the analysis of resource input and waste
output. The metabolism analysis has increasingly become
an important means to evaluate the soundness of eco-
economic system [1,2]. The study of mate ri al m etabolism
analysis has, from its initial focus on single elements and
basic raw materials, gradually emphasized the relation-
ship among multiple metabolic processes, with study
dimensions being increasingly widened [3]. The main
study methods of metabolism analysis include material
flow analysis (MFA), input-output analysis (IOA) and
emergy analysis (EMA), etc. Some scholars hold that
energy flow analysis is a vital way to comprehensively
understand the metabolism of eco-economic system and
may compensate for the disadvantages of material flow
analysis [4,5]. Based on emergy analysis, many scholars
have expounded the material flow and energy f low proc-
esses of eco-economic system and the system operation
efficiency from different perspectives [6-8]. With Chong-
qing Municipality as an example, emergy theory is adopted
in this paper to focus on the quantitative analysis of the
metabolism of regional eco-economic system, diagnose
the internal mechanism of resource and en ergy utilization
and conversion, explore the optimal management mode
of regional energy flow and the optimal energy use stru-
cture, provide theoretical guidance for selection of ap-
propriate regional system metabolic mode, and offer
measures and suggestions on promoting the sustainable
development of Chengdu-Chongqing Growth Pole.
2. Overview of the Region Under Study
Chongqing, between North Latitude 28°10'-32°13' and

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 33
East Longitude 105°11'-110°11', is located at a junction
area between relatively-more-developed East China and
resource-abundant West China, neighboring Hubei Pro-
vince and Hunan Province in the east, Guizhou Province
in the south, Sichuan Province in the west and Shaanxi
Province in the north. As a region with a mid-subtropical
humid monsoon climate, it is hot in su mmer and warm in
winter, characterized by light and heat in the same season,
long frost-free period, abundant rainfall as well as humid
and frequent overcast days. Average temperature is
19.0˚C and annual rainfall is 1 439 mm. With a total land
area of 82 400 km2, the altitude of Chongqing gradually
lowers from north-south to the valley of the Yangtze
River. Northwestern and central parts of Chongqing are
mostly hilly areas and low mountainous areas. With 19
districts and 21 counties under administration, Chongqing
boasts a total population of 3 235.3 × 104 and GDP of
RMB 4 122.5 × 108 in late 2007. Chongqing is the largest
economic center in the upper reach of the Yangtze River,
a key industrial and commercial city in Southwest China
and a hub of water and land traffic. In recent years,
Chongqing has made a lot of beneficial explorations in
developing circular economy and brought about huge
economic, social and ecological benefits. However, the
traditional growth mode of “large-quantity production,
large-quantity consumption and large-quantity waste” has
not been completely changed, and resource and envi-
ronmental issues have increasingly become bottlenecks
that restrain further economic advancement.
3. Study Methods
Based on the solar emergy conversion rates of various
substances (energies), emergy an alysis method is adopted
to quantitatively analyze the energy flow in ecological
system and economic system, and, through computation
of various metabolic indexes, to scientifically and rea-
sonably analyze and evaluate the regional material me-
tabolism.
3.1. Emergy Theory
Emergy (unit: solar emjoules) is a concept developed
from system ecology and eco-economics. The emergy
theory is a method of quantitative analysis combining
ecological system and economic system and according to
the solar emergy conversion rates of various substances
(energies) by regarding solar energy as the standard, in
view of the fact that all energies originate from solar en-
ergy [8].
The emergy theory is to establish relations among dif-
ferent energy levels .and is to contact the economic sys-
tem and ecological system of the bridge. Because it pro-
vides a common scale for measuring and comparing
various energies, metabolic indexes of urban system are
computed on this basis so as to scientifically and rea-
sonably analyze and evaluate the urban system metabo-
lism.
3.2. Data Sources
The original data adopted in this paper come from:
Chongqing Statistical Yearbooks from 2003 to 2008 [9],
Chongqing Statistical Communiqués on National Eco-
nomic and Social Development, and the statistical data,
statement s and reports of relevant departments.
3.3. Compilation of the Metabolic Emergy Table
of Urban System
First, main energy items of urban system metabolism in
Chongqing during 2002 ~ 2007 are listed, including re-
newable environmental resources, non-renewable envi-
ronmental resources, renewable organic energies, non-
renewable industrial auxiliary energies, renewable re-
source product output and non-renewable resource prod-
uct output, etc.; then, flow quantities of energies are ob-
tained according to the energy computation formula, ex-
pressed as energy flow (J), material flow (g) and money
flow ($). After that, different energy units are converted
into a unified emergy unit according to the emergy con-
version rates of different resources so as to establish a
metabolic emergy table of urban system in Chongqing
(see Annex 1). All the solar emergy conversion rates and
emergy computation formulas of substances (energies) in
this paper are cited from the references [10-13].
3.4. Evaluation Index System of Metabolic
Emergy of Eco-Economic System
Based on the original emergy evaluation index system
[5,6,9,10], the index system of metabolic analysis of
eco-economic system in Chongqing is established from
three perspective of metabolic emergy flux, emergy effi-
ciency and metabolic evaluation. See Table 1 for the
details.
3.4.1. Analysis Index of Metabolic Emergy Flux
Analysis indexes of metabolic emergy fluxes refer to the
emergy fluxes of the system itself and the emergy fluxes
of resource and service outputted from system metabo-
lism [6], including emergy fluxes of metabolic input,
metabolic output and metabolic waste of eco-economic
system, which consist of 15 indexes (Table 1). Renew-
able resource emergy is numerically equal to the sum of
renewable environmental resource and renewable organic
energy, of which renewable environmental resource
emergy input mainly consists of solar energy, wind en-
ergy, rain chemical energy, rain potential energy, heat
from the Earth rotation, and timber, etc. As solar energy,
wind energy, rain chemical energy and rain potential

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 34
Table 1. Index system of emergy-based metabolic fluxes and metabolic analysis.
Emergy Index Calculation ExpressionMeaning
Renewable environmental
resource (R1) Input of self-owned environmental resource em e rgy of the system
Renewable organic energy
(R2) Input of self-owned auxiliary e n ergy of the system
Renewable resource emergy
(R) R1 + R2 Self-owned renewa ble emergy w ealth of the system
Non-renewable environmental
resource (N1) In p u t of self-owned e n vironmental resource emergy of the system
Non-renewable industrial
auxiliary energy (N2) Input of self-owned auxiliary e n ergy of the system
Non-renewable resource
emergy (N) N1 + N2 Self-owned non-renewable emergy wealth of the syste
Gross domestic product (GDP) Economic yearly gross domestic product
Import emergy (I MP ) System emergy inputted from the outside
Export emergy (EXP) System emergy outputted to the outside
Money flow (M) GDP + IMP + EXP Total money emergy wealth of the economic system
Metabolic
input
Total input emergy (U) R + N + IMP Total emergy wealth owned by the system
Waste emergy (W) Waste emergy discharged by the system to the
outside
Renewable resource products
(O) Emergy wealth produced from system metabolism
Non-renewable resource
products (F) Emergy wealth p roduced from syst em metabolism
Metabolic
emergy
fluxes
Metabolic
output
Total emergy output (U`) O + F Total emergy wealth p roduced from system me-
tabolism
Emergy self-sufficiency rate
(ESR) (R + N)/U Self-support and sustaining capacity of the system
Emergy waste rate (EWR) W/R Recycling capacity of the system
Emergy yield rate (EYR) (R + N + IMP)/IMP Economic benefits of t h e s ystem
Renewable resource emergy
ratio (R) R/U Environmental potential o f the system
Non-renewable resource
emergy ratio (N) N/U Pressure of system resource utilization on the envi- ronment
Emergy efficiency
Waste flow emergy ratio (W`) W/U Pressure of system discharge w a st e on the envir o n -
ment
Metabolic efficiency (u) (O + F)/U Input to output ra tio during m etabolism
Metabolic intensity (d) (O + F + M)/U Sum of metabolic flows of metabolic system pass-
ing the analysis interface
Metabolic environmental
impact (EI) W Sum of environmental impact caused by pollutants discharged during metabolism
Metabolic evaluation
Metabolic ecological stress
(ELR) (N + IMP)/R Indirect impact of m etabolic system on ecological system
Note: All the indexes and calculation f ormulas in this table are cited from the references [7,8,11,12].

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 35
energy are compounds from the same process, only the
maximum item of them is counted in the merging to
avoid repeated computation. Non-renewable resource
emergy is numerically equal to the sum o f nonrenewab le
environmental resource and non-renewable industrial
auxiliary energy. Non-renewable environmental resource
emergy input is the sum of the emergy of all minerals,
raw coal and natural gas, etc. and the emergy loss of sur-
face soil layer. Import emergy of purchased resources of
urban ecological system is noted as IMP; total emergy (U)
means the total “wealth” of urban eco-economic system,
which is numerically equal to the sum of the renewable
and non-renewable resources of the system itself and the
import emergy of the system. Non-renewable resource
products mainly include raw coal, natural gas, steel ma-
terials, and aluminum materials, etc. Renewable resource
products mainly include tap water, hydropower, agricul-
tural products, animal products, and aquatic products, etc.
Waste emergy (W) refers to the emergy of discharged
pollutants, which is the sum of the emergy of waste water,
waste gas and solid wastes.
3.4.2. Analysis Index of Emergy Efficiency
System emergy efficiency should include correspond-
ing indexes reflecting economic efficiency, resource
utilization efficiency and pollutant discharge efficiency.
Evaluation indexes in this paper mainly include 6 items:
emergy self-sufficiency rate (ESR), emergy waste rate
(EWR), emergy yield rate (EYR), renewable resource
emergy ratio (R’), non-renewable resource emergy ratio
(N’) and waste emergy ratio (W’), among which, emergy
self-sufficiency rate is used to evaluate utilization of
self-owned resources of the system and self-support ca-
pacity of the system, emergy waste ratio is to evaluate
availability of wastes discharged from the system and
recycling capacity of the system, emergy yield rate is a
kind of criterion to measure system operation efficiency,
which is similar to the “output-input ratio” (outpu t/input)
in economic analysis, renewable resource emergy ratio
reflects environmental potential of the system, and non-
renewable resource emergy ratio and waste emergy ratio
represent the operation efficiency of regional system
from perspectives of resource utilization and waste dis-
charge respectively, which can be important indexes for
metabolic emergy efficiency evaluation [6].
3.4.3. Metabol i c Evaluati on Inde x
China is in a rapid urbanization process. Production and
consumption of resources not only support economic
growth of cities/municipalities, but also influence eco-
logical stress, environmental impact and sustainable de-
velopment of public health, etc., making it imperative to
evaluate regional sustainable development capacity
through system metabolism. Evaluation indexes mainly
include metabolic efficiency (u), metabolic intensity (d),
metabolic environmental impact (EI) and metabolic eco-
logical stress (ELR) [2,11]. Metabolic efficiency refers to
the effective part of metabolic flows to the final user,
basically defined as the input to output ratio during me-
tabolism. Metabolic intensity is defined as the sum of
metabolic flows of the system passing the analysis inter-
face in a unit time, for which, the bigger the ratio is, the
more complicated the structure of urban metabolic sys-
tem is, the more perfect the storage system is, the more
sufficient the feedback sector is, and the higher the inte-
gral stability and optimization degree of the system is.
The essential difference between ecological stress and
environmental impact lies in their different positions in
metabolic system; the former is upstream end impact,
while the latter is downstream end impact. Environ-
mental impact in metabolic an alysis is de fined as th e su m
of environmental impacts of pollutants directly dis-
charged during metabolic processes, while waste emergy
(W) means the emergy of discharged pollutants, i.e. the
sum of the emergy of waste water, waste gas and solid
wastes. Thus metabolic environmental impact can be
expressed in waste emergy. Operation of metabolic sys-
tem not only leads to environmental impact that can be
directly measured, but also produces a series of indirect
impacts on regional and even global ecological systems,
and these impacts together are collectively referred to as
ecological stress. Due to difficulties in study methods,
scale conversion and data acquisition, this paper adopts
emergy environmental loading ratio index (ELR) to rep-
resent the pressure of metabolic activities on ecological
system. When ELR < 3, the environmental stress is small,
when 3 < ELR < 10, the environmental impact is at an
intermediate level; when ELR > 10, the environmental
stress is especially great [6].
4. Results and Analysis
Based on Chongqing Statistical Yearbooks from 2003 to
2008, Chongqing Statistical Communiqués on National
Economic and Social Development and the statistical
data, statements and reports of relevant departments [12],
energy, material and money flow data in Chongqing from
2002 to 2007 are selected to analyze and evaluate the
metabolism of Chongqing eco-economic system. After
the original data are converted to a unified emergy unit
and simplified and merged into each metabolic emergy
flux, the emergy data are taken into the above calculation
formulas of emergy efficiency and metabolic evaluation
index, and the emergy evaluation table of metabolism of
Chongqing Municipality in recent 6 years can be ob-
tained (Table 2).

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 36
Table 2. Metabolic emergy evaluation of chongqing municipality from 2002 to 2007.
Item Year 2002 Year 2003 Year 2004 Year 2005 Year 2006 Year 2007
R(×1023sej) 1.020 1.190 1.180 1.160 1.090 1.160
N(×1024 sej) 1.380 1.380 1.580 1.770 1.740 1.930
IMP(×1022sej) 0.776 1.050 1.750 1.780 2.130 2.950
EXP(×1022sej) 1.015 1.451 1.900 2.291 3.045 4.087
GDP(×1023sej) 2.070 2.363 2.819 3.285 3.785 4.701
M(×1023 sej) 2.250 2.360 3.180 3.690 4.300 5.400
U(×1024 sej) 1.490 1.510 1.720 1.910 1.880 2.080
W(×1022 sej) 2.600 2.590 2.530 2.810 2.654 2.247
O(×1022 sej) 3.840 4.100 4.360 4.600 4.360 4.660
F(×1023 sej) 7.060 8.040 8.500 9.940 12.000 14.000
U`(×1023 sej) 7.450 8.450 8.940 10.400 12.400 14.500
ESR 0.995 0.993 0.990 0.991 0.989 0.986
EWR 0.255 0.218 0.214 0.242 0.243 0.194
EYR 192.000 144.000 98.000 107.000 88.000 70.500
R` 0.068 0.079 0.069 0.061 0.058 0.056
N` 0.927 0.914 0.921 0.920 0.930 0.930
W` 0.017 0.017 0.015 0.015 0.014 0.011
u 0.500 0.560 0.520 0.550 0.660 0.700
d 0.649 0.718 0.710 0.740 0.900 0.960
EI(×1022 sej) 2.600 2.590 2.530 2.810 2.654 2.247
ELR 13.700 11.700 13.600 15.500 16.100 16.800
Note: All data used for calculation in this table come from Chongqing Statistical Yearbooks from 2003 to 2008 [9], and all emergy conversion rates come from
the referenc es [7,8,10-13].
4.1. Metabolic Emergy Flux
4.1.1. Metabol i c Input Analysis
It is known from Table 2 that, the total emergy utiliza-
tion in Chongqing eco-economic system is mainly non-
renewable resource emergy, which amounted to 92.3% of
the total emergy in 2007, while renewable resource
emergy and import emergy only occupied a small portion
of the total emergy, accounting for 5.6% and 1.4% of the
total emergy respectively in 2007. Non-renewable re-
source emergy mainly consists of emergy loss of surface
soil layer, raw coal and natural gas, and the 3 items of
emergy input account for 99.0% of the non-renewable
resource emergy input. Landforms of Chongqing are
mainly composed of mountainous areas. The severity of
water and soil loss indicates over-intense development of
non-renewable resource in Chongqing, indicates that the
urban system development is still based on consumption
of non-renewable fossil fuel and mineral matters. Hence,
the utilization structure should be further improved to
replace some non-renewable resources, thus to promote
the sustainable development of Chongqing eco-economic
compound ecological system.
From 2002 to 2007, renewable resource emergy, non-
renewable resource emergy and import emergy in eco-
economic system of Chongqing were increased in gen-
eral (Figure 1), with an annual growth rate of 2.9%,
7.1% and 32.0% respectively. During the 6 years, money
flow emergy and its composition were also increased.
Money emery reached 5.40 × 1023sej in 2007, with an
annual growth rate of 19.6%. Import emergy, export
emergy and GDP emergy of Chongqing in 2007 were 3.8
times, 4 times and 2.3 times of those in 2002 respectively.
Operation of eco-economic system metabolism in Chong-
qing mainly depends on input of local resources in the
mass. Import emergy, compared with local resource
emergy, is low, but its annual growth rate is obviously

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 37
higher than that of local resource emergy, which shows
that, as economy develops, regional metabolic system
increasingly depends on external resources, and openness
will be improved year by year. Thus, openness to the
outside should be further improved, and external emergy
should be extensively introduced to improve emergy
feedback rate and alleviate resource stress of the region.
4.1.2. Metabolic Output Analysis
As waste utilization product emergy still appears in the
form of renewable resource products and non-renewable
resource products, the sum of renewable resource prod-
ucts and non-renewable resource products are taken as
the total output of eco-economic system metabolism to
avoid repetitive computation.
From 2002 to 2007, non-renewable resource products
and total output emergy in the metabolic system of
Chongqing were increased, increasing in 2007 to 1.98
times and 1.95 times of those in 2002 respectively, while
renewable resource products increased slowly in fluctua-
tion (Figure 2). The total output of metabolism in
Chongqing varied mainly with the increase of non-re-
newable resource products. Non-renewable resource
products accounted for 97.0% of the total metabolic out-
put in 2007, which indicated that Chon gqing metabolism
still mainly depended on local non-renewable resource,
and the renewable resource utilization was low, which
needs to be strengthened.
Figure 1. Change trend of metabolic emergy input in
chongqing.
Figure 2. Change trend of metabolic emergy output in
chongqing.
Metabolic input emergy and metabolic output emergy
in Chongqing showed similar growth trends, while the
average annual growth amount (1.18 × 1023sej) and the
average annual growth rate (7.1%) of metabolic input
were less than the average annual growth amount (1.41 ×
1023sej) and the average annual growth rate (14.3%) of
metabolic output. In 2007, the total metabolic output
accounted for 70% of the total metabolic input, indicat-
ing that resource cycling utilization measures of
Chongqing Municipality contributed to the alleviation of
metabolic input of eco-economic system, and there had
increasing trend in material inventory of the urban meta-
bolic system.
4.2. Emergy Efficiency Analysis
From 2002 to 2007, introduction of external resources
into Chongqing Municipality increased slowly, and sys-
tem emergy self-sufficiency rate, emergy waste rate and
emergy yield rate were obviously decreased in general
(Figure 3(a)). During the 6 years, The openness of eco-
economic system in Chongqing was no t significant. Sys-
tem metabolism still greatly depended on internal re-
sources. Emergy self-sufficient rate of the system was
98.6% in 2007, a little lower than that in 2002 (99.5%).
Emergy waste rates of Chongqing were 25.5%, 21.8%,
21.4%, 24.2%, 24.3% and 19.4% respectively fro m 2002
to 2007, indicating that the level of waste-resource recy-
cling in Chongqing was unstable during the 6 years,
which requires further improvement of wastes treatment
techniques. However, the overall level was still de-
creased slowly. With the development of environmen-
tally-friendly technologies, the emergy waste rate is ex-
pected to further decrease. The emergy output rate was
192 in 2002, 2.7 times of that in 2007, indicating that the
operation efficiency of regional metabolic system was
not improved under the same economic emergy input.
Renewable resource emergy ratio and waste emergy ratio
were both decreased (Figure 3(b)), indicating that both
the use of renewable resources and the pressure of waste
discharge on environment in Chongqing decreased over
the 6 years. Renewable resource emergy ratio increased
significantly in 2003, mainly because the annual rainfall
in renewable environmental resources and the human
emergy in organic energy in 2003 were significantly
higher than those in 2002 and 2004. Non-renewable re-
source emergy ratio was increased in general from 2003
to 2007, which showed that the operation efficiency of
non-renewable resource utilization was strengthened
during this period, while the utilization rate in 2002 was
at a higher level, due to a relatively smaller total emergy
of 1.49 × 1024sej.
The above analysis shows that eco-economic system in
Chongqing still belongs to a resource consumption type.

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 38
(a)
(b)
Figure 3. Emergy-based analysis of metabolic efficiency for
urban system in Chongqing.
Economic development does not depend greatly on ex-
ternal factors. Due to increasing pressure of urban de-
velopment on environment, the mode of economic growth
needs to be changed, the industrial structure needs to be
updated, and the resource supply and demand structure
needs to be optimized. Specifically, utilization of non-
renewable resources in great quantities should be trans-
formed into more dependence on input of renewable re-
sources, so as to improve resource utilization rate and
waste-resource recycling rate [15].
4.3. Analysis of Metabolic Evaluation Indexes
4.3.1. Analysis of Metabolic Efficiency and Intensity
Metabolic efficiency and metabolic intensity of eco-
economic system in Chongqing from 2002 to 2007
showed similar growth tendencies (Figure 4). Those in
2007 were 1.4 times and 1.5 times of those in 2002 re-
spectively, with an annual growth rate of 7.34% and
8.41% respectively, indicating that, with rapid economic
development, metabolic efficiency and intensity were
both higher than before; the effective part of metabolic
process was also relatively strengthened during this pe-
riod; the structure of metabolism system became in-
creasingly complicated, the storage system was increas-
ingly perfect, the feedback sector was increasingly suffi-
cient, and the integral stability and optimization of the
system was also relatively improved.
4.3.2. Analysis of Metabolic Environmental Impact
and Ecological Stress
Metabolic environmental impact (EI) during the 6 years
showed a trend from rising to dropping in the mass.
Waste emergy did not change significantly compared to
the rapid economic growth. Total amount of discharge of
waste gas, water and residues in 2007 dropped slightly
over that in 2002, i.e. 86.4% of that in 2002, indicating
that Chongqing have paid much attention to the end-of -pipe
treatment of industrial waste in recent years and the eco-
logical environment has obtained increasing focus and
improvement, while pollution treatment input and
strength should be enhanced to improve environmental
conditions.
The environmental loading ratio of eco-economic sys-
tem in Chongqing was increased. The environmental
loading ratio in 2007 was 1.23 times of that in 2002, in-
dicating that the pressure of urban system in Chongqing
on local environment was not weakened with the urban
development (Figure 5). Environmental loading ratios
over the 6 years were all higher than 10, fluctuating be-
tween 16.8 and 13.7. The opera ti on of metabolic sy stem in
Chongqing has exerted significant indirect influence on
upstream front-end of the ecological system. Although a
Figure 4. Development trends of system metabolic efficiency
and intensity in chongqing.
0
2
4
6
8
10
12
14
16
2002 2003 2004 2005 2006 2007
Year
18
ELR
Figure 5. Development trend of metabolic ecological stress
in chongqing.

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 39
high environmental loading ratio indicates stronger sys-
tem emergy utilization [16], the system will develop in a
negative trend once the strong utilization exceeds the
support threshold of the system. In the urban system of
Chongqing, efforts should be made to maximize the
utilization of local renewable resources and protect non-
renewable resources, such as sustainable utilization of
mineral resources.
5. Conclusions and Development Suggestions
5.1. Conclusions
1) The total available emergy in Chongqing during 2002
~ 2007 was quite abundant, and its annual growth and
annual growth rate were 1.18E + 23sej and 7.07% re-
spectively, with higher economic development. Local
renewable natural resources were relatively in shortage,
mainly consisted of local non-renewable resources (ac-
counting for 92.79% of the total emergy in 2007). It is
learned from the above that the economic development
mainly relies on internal resources, and is on the basis of
high-intensity use of local resources. Therefore, as a
whole, the urban system metabolism in Chongqing is
relatively closed and the utilization degree of external
emergy is low.
2) Metabolic output of the urban system of Chongqing
and its structure were both increased. Its annual growth
and annual growth rate were 1.41E + 23sej and 14.3%
respectively, both higher than the metabolic input
emergy. This indicates that the recycling utilization and
the resource recycling utilization of waste have made
some contributions to alleviating the urban system
metabolic input, and the material inventory of urban
metabolic system is with net increase.
3) Money flow emergy of the urban system of
Chongqing and its structure were both increased. The
money emergy amount in 2007 reached 5.4E + 23sej,
with an annual growth of 6.3E + 22sej and an annual
growth rate of 19.6%. This indicates that, with develop-
ment and status importance improvement of the economy
in Chongqing, Chongqing will depend more and more on
external environment, the input of external resources will
keep growing, and th e openness will rise year by year as
well.
4) Indexes reflecting emergy efficiency were mostly
decreased, among which, emergy self-sufficiency rate,
emergy waste rate, emergy yield rate, renewable resource
emergy ratio and waste emergy ratio in 2007 were 99%,
76%, 37%, 82% and 62% of those in 2002. By contrast,
non-renewable resource ratio was fluctuating to rise. This
indicates that, environmental impact of the waste dis-
charged by the urban system on environment is turning
better, but the urban system of Chongqing is a resource
consumption one on the whole, and waste treatment
techniques and resource utilization rate are yet to be im-
proved.
5) Metabolic effect, metabolic efficiency and meta-
bolic intensity of the urban system were keeping rising,
with an annual growth rate of 14.3%, 7.34% and 8.41%
respectively. The metabolic environmental impact was
fluctuating to decrease. This indicates that the awareness
of environmental protection and reasonable resource
utilization is gradually improving and the self-organiza-
tion capacity and development potential are both devel-
oping in an optimistic trend. However, the rising trend of
metabolic ecological stress shows that the potential treat
of resource consumption of Chongqing urban system
upon the upstrea m end of the ecological system is gradu-
ally increasing. Therefore, only through reasonably re-
gulating and controlling the interactive relationship be-
tween metabolic fluxes and through promoting the coor-
dinated symbiosis of urban metabolic emergy fluxes can
the sound operation of urban metabolic system be
achieved.
5.2. Suggestions on Sound Development of the
Urban Metabolic System in Chongqing
Currently, Chongqing should, based on its original de-
velopment conditions, continuously introduce new tech-
nical innovative components, improve the utilization
efficiency of input emergy, raise the emergy yield rate
and waste-to-resource efficiency, reduce the system reli-
ance on non-renewable resources, strengthen the devel-
opment of renewable resources, and increase the social
and economic benefits obtained from a unit environ-
mental pressure so as to achieve sound cycling of system
metabolism. The following should be done in order to
achieve sound development of the urban system metabo-
lism:
1) To improve system openness and enhance input of
external emergy. Non-renewable resource emergy, re-
newable resource emergy and import emergy in Chong-
qing in 2007 were 92.79%, 5.58% and 1.42% respec-
tively of the total emergy, indicating that environmental
and resource pressures became increasingly obvious with
the economic development. Despite a great annual growth
rate (32%) of the import emergy during 2002 ~ 2007, the
total amount was small; thus, openness to the outside
should be increased and external emergy (such as tech-
nologies, equipment and resources) should be extensively
introduced to improve emergy feedback ratio, help
emergy grow more rapidly and alleviate local resource
pressure. Moreover, high-quality talents should be intro-
duced in great numbers to improve talent structure and
lay a human resource foundation for sound development
of the system metabolism in Chongqing.

Analysis of Material Metabolism of Eco-Economic System in Chongqing Based on the Emergy Theory 40
2) To guide with policies, adjust the industrial struc-
ture and change the mode of economic growth. Since
environmental loading ratios reflecting the metabolic
ecological stress of Chongqing urban system all are
higher than 10, fluctuating between 16.8 and 13.7, the
government needs to consider how to protect environ-
ment and integrate macro-policy requirement of ecologi-
cal factors while satisfying human needs. Besides, in the
total emergy amount of Chongqing, non-renewable re-
source emergy accounts for the majority part, indicating
that the economic growth in Chongqing mainly relies on
the input of nonrenewable resources, in a mode of eco-
nomic growth with high resource consumption, which
seriously damages ecological and environmental resources
and does not conform to the sustainable development
concept in a harmonious society. Therefore, efforts
should be made to adjust the industrial structure, change
the mode of economic growth from extensive growth to
intensive economy, rely on high technologies, utilize
resources, well protect natural resources and ecological
environment, improve comprehensive resource utiliza-
tion efficiency and enlarge environmental capacity of
regional development.
3) To develop educational system and promote com-
mercialization of study output. Only through education
can advanced technologies and experience with a great
amount of creative emergy be converted and amplified
into emergy and wealth to promote economic develop-
ment and social progress.
4) To reasonably organize planning and vigorously
develop tourism. The decrease trend of emergy yield rate
in Chongqing indicates that Ch ong qing should streng then
industries with higher net emergy yield rates such as
tourism, to make better advantages of natural and geo-
graphical environments and cultural scenery, and sig-
nificantly promote local economy.
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