Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
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Commun Nonlinear Sci Numer Simulat
journal homepage: www.elsevier.com/locate/cnsns
Comparison of typical mega cities in China using emergy synthesis
L.X. Zhang a, B. Chen a, Z.F. Yang a,*, G.Q. Chen a,b, M.M. Jiang a, G.Y. Liu a
a
b
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing 100875, China
National Laboratory for Complex Systems and Turbulence, Department of Mechanics, Peking University, Beijing 100871, China
a r t i c l e
i n f o
Article history:
Received 22 December 2007
Received in revised form 25 February 2008
Accepted 1 March 2008
Available online 2 June 2008
PACS:
87.23.n
89.60.k
Keywords:
Emergy
Resource structure
Resource use efficiency
Mega urban system
a b s t r a c t
An emergy-based comparison analysis is conducted for three typical mega cities in China,
i.e., Beijing, Shanghai and Guangzhou, from 1990 to 2005 in four perspectives including
emergy intensity, resource structure, environmental pressure and resource use efficiency.
A new index of non-renewable emergy/money ratio is established to indicate the utilization efficiency of the non-renewable resources. The results show that for the three mega
urban systems, Beijing, Shanghai and Guangzhou, the total emergy inputs were
3.76E+23, 3.54E+23, 2.52E+23 sej in 2005, of which 64.88%, 91.45% and 72.28% were
imported from the outsides, respectively. As to the indicators of emergy intensity involving
the total emergy use, emergy density and emergy use per cap, three cities exhibited similar
overall increase trends with annual fluctuations from 1990 to 2005. Shanghai achieved the
highest level of economic development and non-renewable resource use efficiency, and
meanwhile, lower proportion of renewable resource use and higher environmental pressure compared to those of Beijing and Guangzhou. Guangzhou has long term sustainability
considering an amount of local renewable resources used, per capita emergy used, energy
consumption per unit GDP and the ratio of waste to renewable emergy. It can be concluded
that different emergy-based evaluation results arise from different geographical locations,
resources endowments, industrial structures and urban orientations of the concerned
mega cities.
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
Urban economic and ecological systems are physically connected by the throughput of energy and matter from natural
ecosystems, and by other environmental goods and services which sustain economic activities. Since mechanisms that link
regional economy and ecosystem dynamics exist, a proper understanding of their properties requires explicit investigation of
these system–environment relations [1]. Monetary valuation of ecosystem service and natural capital may be useful to demonstrate their economic value but insufficient to measure the intrinsic worth of the life-support function of ecosystem.
Assessing the intrinsic value of the environment in providing life-support services requires a new accounting system that
can assure the contribution of a non-market oriented natural environment to the economic systems [2]. Emergy analysis
is such an accounting method that can be used to assess complex relationships between the economy and its support environment because the work of both is expressed in equivalent terms [3,4]. The intrinsic value of ecosystems in biological
terms is emphasized, whether human preference fully recognizes that value or not [2]. By introducing the emergy concept,
Odum re-directed his focus from the interface between human societies and fossil sources to that between human societies
and the environment, identifying the free ‘environmental work’ as the donor of resources supporting human activities [5].
* Corresponding author. Tel.: +86 10 58807951; fax: +86 10 58800397.
E-mail address: [email protected] (Z.F. Yang).
1007-5704/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.cnsns.2008.03.018
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
The theoretical and conceptual basis for emergy analysis is grounded in energetics and systems ecology. Emergy analysis
considers all systems to be networks of energy flows and determines the emergy value of the systems involved through a
synthetic approach, providing a general accounting mechanism that allows us to view the economy and the environment
on the same income statement and balance sheet [6]. Readers interested in more detailed descriptions and relevant analyzing procedures may consult Refs. [3,7–9]. Since the early 1980s, the emergy framework has been widely used to analyze systems as diverse as ecosystems, industries, and economies [10–14]. In addition, the thermodynamic concept of emergy is
extraordinary useful for the systematic evaluation of urban ecosystem, since it is necessary to obtain not only a reliable evaluation of a system’s or region’s performance over a period of time, but also the system’s or region’s sustainability compared
with those of other systems or regions [15]. Therefore, emergy synthesis has also been employed in the evaluation of urban
areas in recent years [2,15–19].
In this paper, a comparison analysis was conducted based on emergy for urban systems of Beijing, Shanghai and Guangzhou, three typical and representative mega cities in China from 1990 to 2005. Time-series based comparison analysis of these
cities would shed light on both overall evolvement trends and regional variations.
2. Study areas
Different from other countries, the urban classification in China was made according to the non-agricultural population
size (fei nong ye ren kou) in urban districts, excluding the county population under the jurisdiction of the city, of which mega
cities refer to those with population over 2 million [20]. According to the official statistical yearbook [21], the number of Chinese mega cities had reached 13 at the end of 2005, among which Beijing, Shanghai and Guangzhou are three most representative urban economic centers and internationally linked cities (Fig. 1). It is necessary to make a distinction that the
whole administrative region, i.e., the central urban districts plus the counties under the jurisdiction, were considered in practice of our analysis, however. In other words, when we refer to a city, Beijing for example, its boundary covers the whole
administrative area of Beijing rather than the central urban area.
General situations of Beijing, Shanghai and Guangzhou are listed in Table 1. Beijing, the capital city of China, is in the
north of China and located at 115°250 –117°300 E and 39°280 –41°250 N in the temperate climatic zone with a mean annual temperature of 12 °C. Precipitation averages 640 mm per annum [22,23]. Recent years, heavy industries in Beijing are gradually
Fig. 1. Locations of Beijing, Shanghai and Guangzhou.
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
Table 1
General situations of Beijing, Shanghai and Guangzhou in 2005
Item
Beijing
Shanghai
Guangzhou
Area (km2)
Rainfall (mm)
Associated river basin
Total population (104)
Population density (person/km2)
GDP (1010 USD)
Per capita GDP (USD)
Per capita water resources (m3)
Water consumption per thousand USD GDP (m3)
Energy consumption per thousand USD GDP (tce)
The proportion of the three industries
16410.54
410.7
Haihe River basin
1538.0
937
8.40
5464.29
212.61
61.79
0.98
1.4:29.5:69.1
6340.50
1059.8
Yangtse River basin
1352.39
2133
11.2
8213.00
203.71
152.76
1.07
0.9:48.9:50.2
7434.4
1938.2
Pearl River basin
750.53
1010
6.44
6784.13
993.26
160.36
0.95
2.53:39.68:57.79
being replaced by the less-polluting industries such as financial and other service industries, and high-technology manufacturing. Located in the middle of China’s mainland coastline (120°510 –122°120 E, 30°400 –31°530 N) and at the estuary of the
Yangtse River, Shanghai has an area of 6340.5 km2, with a mean annual temperature of 15 °C and a mean annual precipitation of 1100 mm. As the economic center of eastern China, its industrial structure includes heavy industries, such as steel,
petrol, and automobile production, along with export processing and financial and other service industries [24,25]. Guangzhou is located in south China between 112°570 –114°30 E and 22°260 –23°560 N, with an area of 7434.4 km2 and annual precipitation of 1689.3–1876.5 mm. It lies in the piedmont and coastal plain physiographic regions, declining from the mountain
areas in the north to sea level at the confluence of the Pearl River in the south. As an intensive agricultural area embedded
with a dike-pond system, Guangzhou has experienced rapid economic development and urbanization over the past decades,
with the value of GDP being 64.43 billion USD in 2005, double that of what it was in 1999 [26].
These concerned three cities share the same characteristics with most metropolitan regions in the world, being located at
the mouths of the three big rivers and originated from the fertile plains of these rivers, i.e., Yongding River (one branch of
Haihe River system), Yangtse River and Pearl River, respectively. Flat topography, fertile soils resulting from sedimentation
from upstream areas and rivers set the fundamental natural resource basis for the urban development as shown in Fig. 1.
However, all the three cities are confronted with many similar problems including pollutions, shortage of water resource,
lost of the high-yield agricultural land, large floating population from rural areas and increased disaster risk.
3. Methodology
With regard to the varied qualities of energy inherent in the hierarchy of system components, emergy is defined as the
available energy (exergy) of one kind previously used up directly and indirectly to make a service or product, usually quantified in solar energy equivalents and expressed as solar emJoules (sej) [27]. The amount of input emergy dissipated (availability used up) per unit output exergy is termed as solar transformity and correspondingly, the solar emergy of a product or
service is calculated by multiplying units of energy by transformity [5,28]. It represents the emergy investment per unit
product, and as such it is a measure of the way solar exergy is transformed and degraded [5].
Based on the energy circuit language introduced by Odum [8], the conceptual ecological economic system of an urban
area can be represented to illustrate the material and energy flows and the organization of major components that utilize
those resources (Fig. 2). Pathways and interactions show the activities related to resources (e.g., production, consumption,
import, export and accompanied economic exchanges) [6]. The ecological energetic flows into urban system can be aggregated into local free renewable resources (R) and non-renewable resources (N), materials (G), fuels (F) and services (S) from
outside, and the corresponding outputs of city include products and waste (W). The relevant indices and ratios based on
emergy flows can be used to evaluate the behavior of ecological economic systems. For the present case, it is appropriate
to introduce the indices used in our analysis (see Table 2). A new index of non-renewable emergy/money ratio is established
to indicate the resource use efficiency of non-renewable parts. The non-renewable emergy/money ratio is the ratio of total
non-renewable emergy flow in the economy of a region or nation to the GDP of the region or nation, reflecting the nonrenewable resources investment per unit product.
The emergy-based comparison analysis of case cities mainly focuses on four aspects, i.e., emergy intensity, resource structure, environmental pressure and resource use efficiency. Meanwhile, previous evaluation results of Taipei by Huang [29]
and Macao by Lei [15,19] are also incorporated for cross-references. Two years’ results are available for Taipei, i.e., 1991
and 1998, while seven years’ results for Macao, i.e., 1990, 1993, 1995, 1997, 2000, 2003 and 2004.
Statistical data is then collected for detailed information on local production and consumption, imports and exports, and
the economy, as well as on local geomorphology (solar irradiation, rain, soil erosion, ore deposits, water resource, etc.) during
the concerned period from 1990 to 2005 [21,30–32] and processed by transforming mass quantities (kg) and energy quantities (Joule) into equivalent sej through multiplying by the appropriate transformities. All the transformities refer to the
15.83 baseline. Transformity references for respective row number of Tables 3–5 in Section 4 are as follows: rows 1, 2, 3,
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Fig. 2. Systems diagram of the urban ecological economic system.
Table 2
Emergy-based indices for comparison of case cities
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Emergy index
Expression
Renewable emergy flow
Flow from indigenous non-renewable reserves
Imported fuels
Imported goods
Imported services
Waste emergy
Total emergy used (sej)
Fraction used, locally renewable
Emergy self-sufficiency
Emergy density (sej/km2)
Per capita emergy used (sej per cap)
Ratio of waste to total emergy used
Fuel and electricity use per GDP (sej/USD)
Non-renewable emergy/money ratio (sej/USD)
R
N
F
G
S
W
U=N+R+G+S+F
R/U
(R + N)/U
U/area
U/population
W/U
(F + electricity)/GDP
(N + G + F)/GDP
4, 6, 21 from [33]; rows 5 from [34]; rows 7, 11, 15, 18, 22, 23 from [8]; rows 8, 9, 10, 14 from [35]; rows 12, 24, 25 from [28];
row 13 from [36]; rows 16, 17,19, 20 from [37].
In terms of emergy supply, the resources consumption of urban system involves local inputs, renewable or non-renewable, and energies, materials and services imported from outside, domestic or aboard. The energy inputs from environmental
sources are sunlight, wind and rain. Due to their limited natural resources and relatively urbanized land uses, the emergy
flows from renewable sources and local non-renewable sources to the urban economy in urban areas are relatively small.
The degree of dependence on other ecosystems shows a weakness in the competitive capacity of a territorial system, because
the availability of resources for development and maintenance is not under the system’s control [27]. In the long run, only
processes with high percentage of renewable inputs are sustainable [38].
4. Results and discussion
The spread sheets of emergy accounting for Beijing, Shanghai and Guangzhou are listed in Tables 3–5, from which we can
calculate the total emergy uses of the three case cities to be 3.76E+23, 3.54E+23, 2.52E+23 sej in 2005, respectively. The total
emergy uses of three cities exhibited overall increase trends during the concerned period with different annual growth rates
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
Table 3
Emergy synthesis table of resource and economic flows of Beijing 2005
Note
Raw data
Transformity (sej/unit)
Solar emergy (sej)
Em$ values
Renewable sources
1
Sunlight (J)
2
Wind, kinetic (J)
3
Rain, geopotential (J)
4
Rain, chemical (J)
5
Earth cycle (J)
6
Stream flow
Item
7.02E+19
4.31E+16
1.62E+15
3.33E+16
1.81E+16
3.75E+15
1
2.45E+03
4.70E+04
3.05E+04
5.80E+04
3.05E+04
7.02E+19
1.05E+20
7.62E+19
1.02E+21
1.05E+21
1.15E+20
1.57E+07
2.35E+07
1.70E+07
2.27E+08
2.35E+08
2.56E+07
Indigenous renewable energy
7
Hydroelectricity (J)
8
Agriculture production (J)
9
Livestock production (J)
10
Fisheries production (J)
5.04E+14
1.84E+16
1.08E+16
3.02E+14
2.77E+05
1.98E+05
3.42E+05
5.04E+06
1.40E+20
3.65E+21
3.68E+21
1.52E+21
3.12E+07
8.15E+08
8.21E+08
3.40E+08
Non-renewable sources from within Beijing
11
Fuels (J)
12
Soil losses (g)
13
Limestone (g)
14
Sand and gravel (g)
15
Iron ore (g)
2.77E+17
1.58E+12
1.42E+13
4.00E+13
1.83E+13
3.98E+04
1.71E+09
1.68E+09
1.68E+09
1.44E+09
1.10E+22
2.70E+21
2.39E+22
6.72E+22
2.63E+22
2.46E+09
6.03E+08
5.33E+09
1.50E+10
5.88E+09
Imports and outside sources
16
Goods (USD)
17
Services (USD)
18
Fuels (J)
4.91E+10
6.93E+09
1.33E+18
6.92E+12
5.85E+12
6.19E+04
1.21E+23
4.05E+22
8.24E+22
2.71E+10
9.05E+09
1.84E+10
Exports
19
20
4.26E+10
3.62E+09
6.92E+12
5.85E+12
1.47E+23
2.12E+22
3.29E+10
4.73E+09
Resource consumed
21
Water use (J)
22
Fuels (J)
23
Electricity (J)
1.70E+16
1.51E+18
2.04E+17
3.05E+04
5.17E+04
1.59E+05
5.20E+20
7.81E+22
3.25E+22
1.16E+08
1.74E+10
7.25E+09
Waste produced
24
Solid waste (J)
25
Waste water (J)
7.34E+16
8.36E+15
1.80E+06
6.66E+05
1.32E+23
5.57E+21
2.95E+10
1.24E+09
Dollar flow
26
8.40E+10
4.48E+12
3.76E+23
8.40E+10
Goods (USD)
Services (USD)
GDP (USD)
as shown in Fig. 3a and b. Two rapid increasing periods can be identified from Fig. 3b, namely, the early periods of 1990s and
2000s, which are essentially in accordance with the politico-economical changes of whole China.
The ratios associated with emergy intensity are more persuasive than those reflecting the whole situation when used for
comparison in consideration of the disparities of population and administrative area. As shown in Fig. 4a, there exist great
differences of emergy density, with Shanghai possesses the highest, Beijing the lowest and Guangzhou approaches balance
between the two, which to some extent indicate the different urbanization and economic development levels among three
cities. However, once compared with the same available indicators of Taipei and Macao in the particular years mentioned
above, those of Beijing, Shanghai and Guangzhou would be far below with two or three orders in magnitude, which suggests
that the mega cities of mainland China are still intermediate in development level of the world. Nevertheless, the ascending
trends distinguish them from Macao in both emergy density and per capita emergy use due to being in a stage of rapid urbanization. The per capita emergy use of Beijing, Shanghai and Guangzhou increased from 1.17E+16, 1.02E+16, 1.11E+16 sej in
1990 to 2.45E+16, 2.60E+16, 2.65E+16 sej in 2005, respectively, see Fig. 4b. With regard to cross-comparison among the case
cities, Guangzhou, on the whole, has the higher per capita emergy use than those of Beijing and Shanghai. However, the emergy use per capita in Macao is the highest of the five cities by a considerable margin all along the concerned period. Nevertheless, it can be concluded that the disparities in emergy welfare are not so much as economic development levels.
The proportion of the local renewable resources and the self-sufficient ratio in Beijing, Shanghai and Guangzhou from
1990 to 2005 are shown in Fig. 5a and b, respectively, which illustrates that, for all the three cities, the proportions of renewable resources parts were very low and decreased with years. The proportions of renewable resources declined from 0.015,
0.009 and 0.021 in 1990 to 0.003, 0.003 and 0.009 in 2005, respectively, versus values of 0.014 in 1998 for the Taipei and
0.0013 in 2004 for the Macao. The same decrease trends can be found in self-sufficient ratio, see Fig. 5b. However, in the
cases of Beijing and Guangzhou, it was discovered a relatively low level of imported resources with respect to the local resource availability compared to that of Shanghai.
The overall changes of these two indicators suggest that the life-support systems of relative developed mega cities in
China have became highly dependent on purchased non-renewable resources from outside. Further examination of Fig. 5
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
Table 4
Emergy synthesis table of resource and economic flows of Shanghai 2005
Note
Raw data
Transformity (sej/unit)
Solar emergy (sej)
Em$ values
Renewable sources
1
Sunlight (J)
2
Wind, kinetic (J)
3
Rain, geopotential (J)
4
Rain, chemical (J)
5
Earth cycle (J)
6
Stream flow
Item
2.55E+19
3.94E+16
9.71E+13
3.32E+16
1.28E+16
1.21E+16
1
2.45E+03
4.70E+04
3.05E+04
5.80E+04
3.05E+04
2.55E+19
9.66E+19
4.56E+18
1.01E+21
7.42E+20
3.69E+20
8.06E+06
3.05E+07
1.44E+06
3.19E+08
2.34E+08
1.16E+08
Indigenous renewable energy
7
Hydroelectricity (J)
8
Agriculture production (J)
9
Livestock production (J)
10
Fisheries production (J)
0.00E+00
1.96E+16
4.99E+15
1.66E+15
2.77E+05
1.98E+05
3.42E+05
5.04E+06
0.00E+00
3.88E+21
1.70E+21
8.37E+21
0.00E+00
1.23E+09
5.38E+08
2.64E+09
Non-renewable sources from within Shanghai
11
Fuels (J)
12
Soil losses (g)
13
Limestone (g)
14
Sand and gravel (g)
15
Iron ore (g)
3.22E+16
1.93E+12
8.64E+12
5.76E+12
0.00E+00
5.46E+04
1.71E+09
1.68E+09
1.68E+09
1.44E+09
1.76E+21
3.31E+21
1.45E+22
9.68E+21
0.00E+00
5.55E+08
1.04E+09
4.58E+09
3.05E+09
0.00E+00
Imports and outside sources
16
Goods (USD)
17
Services (USD)
18
Fuels (J)
9.89E+10
1.23E+10
2.37E+18
1.44E+12
5.38E+12
4.88E+04
1.42E+23
6.61E+22
1.16E+23
4.48E+10
2.09E+10
3.65E+10
Exports
19
20
9.45E+10
3.56E+09
1.44E+12
5.38E+12
1.36E+23
1.91E+22
4.29E+10
6.03E+09
Resource consumed
21
Water use (J)
22
Fuels (J)
23
Electricity (J)
5.99E+16
2.40E+18
2.67E+17
3.05E+04
4.87E+04
1.59E+05
1.83E+21
1.17E+23
4.24E+22
5.77E+08
3.68E+10
1.34E+10
Waste produced
24
Solid waste (J)
25
Waste water (J)
9.18E+16
1.48E+16
1.80E+06
6.66E+05
1.65E+23
9.85E+21
5.21E+10
3.11E+09
Dollar flow
26
1.12E+11
3.17E+12
3.54E+23
1.12E+11
Goods (USD)
Services (USD)
GDP (USD)
we can observe that Guangzhou and Taipei achieved relatively higher ratios of renewable resources use. Therefore, it can be
deduced that the climatic location is relevant to sustainability of urban areas with regard to natural contribution such as
solar radiation and rain. The lowest values of self-sufficient ratio of Shanghai, Taipei and Macao can be easily explained
by their resources scarcities.
In this analysis, the emergy of wastes exclude emissions into the atmosphere, although these are critical components of
the overall waste flow, due to lack of reliable data [19]. Two indictors, the total waste output and the ratio of waste to total
emergy used, are adopted to show the environmental pressure of pollutions. In Fig. 6a, the rising waste emergy indicates the
environmental pressure increases along with the rapid urbanization course. Guangzhou as well as Taipei had relatively low
level of waste output compared to those of Beijing and Shanghai. Macao had the lowest waste emissions in emergy account
with only 2.98E+20 sej in 2004, which can be attributed to its small area and the less-polluting industry of gambling and
tourism, which is also demonstrated by the ratio of waste to total emergy used. On the contrary, Beijing and Shanghai
are partly relying on heavy manufacturing and pollution-intensive industries, despite great efforts have been made to
achieve deindustrialization. However, there is an inverted U-shaped curve characteristic in the changes of the ratio of waste
to total emergy used, i.e., increasing first and then decreasing, during the concerned period, possibly due to the industrial and
economic transformation in urban areas of China. Nevertheless, Shanghai still has the highest value and Guangzhou the least
among these three cities. Particularly in 1998, the index of Guangzhou is lower than that of Taipei, indicating a relatively low
environmental pressure in urban areas.
Two indicators were adopted to investigate the resource use efficiency in our analysis, i.e., fuels and electricity emergy
use per $ GDP and non-renewable emergy/money ratio. Fuels and electricity play a very crucial role in urban development
and public welfare and can be easily employed to examine efficiency by per capita or per dollar output. As shown in Fig. 7a,
the fuels and electricity consumed per dollar GDP of Guangzhou, compared with those of Beijing and Shanghai, had been in a
relatively low level due to its export-oriented economy. At the early stage of 1990s, the fuels and electricity consumption per
dollar GDP of Shanghai was higher than that of Beijing, but it scale-downed rapidly to be lower than Beijing in 1995. Anyway,
all these three cities has experienced decline of fuels and electricity consumption during the period concerned. It is no doubt
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
Table 5
Emergy synthesis table of resource and economic flows of Guangzhou 2005
Note
Raw data
Transformity (sej/unit)
Solar emergy (sej)
Em$ values
Renewable sources
1
Sunlight (J)
2
Wind, kinetic (J)
3
Rain, geopotential (J)
4
Rain, chemical (J)
5
Earth cycle (J)
6
Stream flow
Item
2.66E+19
1.13E+16
3.68E+15
7.12E+16
1.69E+16
3.57E+16
1
2.45E+03
4.70E+04
3.05E+04
5.80E+04
3.05E+04
2.66E+19
2.77E+19
1.73E+20
2.17E+21
9.82E+20
1.09E+21
6.81E+06
7.08E+06
4.42E+07
5.56E+08
2.51E+08
2.79E+08
Indigenous renewable energy
7
Hydroelectricity (J)
8
Agriculture production (J)
9
Livestock production (J)
10
Fisheries production (J)
1.28E+16
1.19E+16
3.60E+15
1.83E+15
2.77E+05
1.98E+05
3.42E+05
5.04E+06
3.55E+21
2.35E+21
1.23E+21
9.20E+21
9.09E+08
6.01E+08
3.15E+08
2.35E+09
Non-renewable sources from within Guangzhou
11
Fuels (J)
12
Soil losses (g)
13
Limestone (g)
14
Sand and gravel (g)
15
Iron ore (g)
0.00E+00
1.61E+12
2.30E+13
1.54E+13
0.00E+00
0.00E+00
1.71E+09
1.68E+09
1.68E+09
1.44E+09
0.00E+00
2.76E+21
3.87E+22
2.59E+22
0.00E+00
0.00E+00
7.07E+08
9.91E+09
6.64E+09
0.00E+00
Imports and outside sources
16
Goods (USD)
17
Services (USD)
18
Fuels (J)
5.32E+10
4.91E+09
8.44E+17
5.89E+12
5.18E+12
5.18E+04
1.13E+23
2.54E+22
4.37E+22
2.89E+10
6.51E+09
1.12E+10
Exports
19
20
4.47E+10
2.29E+09
5.89E+12
5.18E+12
2.63E+23
1.19E+22
6.73E+10
3.04E+09
Resource consumed
21
Water use(J)
22
Fuels (J)
23
Electricity (J)
4.13E+16
7.59E+17
1.53E+17
3.05E+04
3.98E+04
1.59E+05
1.26E+21
3.02E+22
2.44E+22
3.22E+08
7.73E+09
6.24E+09
Waste produced
24
Solid waste (J)
25
Waste water (J)
1.81E+16
9.32E+15
1.80E+06
6.66E+05
3.26E+22
6.21E+21
8.34E+09
1.59E+09
Dollar flow
26
6.44E+10
3.91E+12
2.52E+23
6.44E+10
Goods (USD)
Services (USD)
GDP (USD)
a
b
0.80
4.00E+23
Beijing
Shanghai
Beijing Shanghai
Guangzhou
Guangzhou
0.60
3.00E+23
0.40
2.00E+23
0.20
1.00E+23
0.00
90-91
0.00E+00
1990
1992
1994
1996
1998
2000
2002
2004
92-93
94-95
96-97
98-99
00-01
02-03
04-05
-0.20
Fig. 3. Total emergy use (a, unit: sej) and their annual variance rate (b) of Beijing, Shanghai and Guangzhou from 1990 to 2005.
that the current extensive deindustrialization and economic reconstructing in China affect energy consumption in many
ways. For example, the relocation of Beijing Shougang Iron and Steel Plant, from Beijing to Caofeidian, Tangshan, Hebei province, may contribute to Beijing’s sharp deduction of energy consumption in recent years. In addition, it is very important to
note that the country’s goal of cutting energy consumption per unit of GDP by 20% and reducing major pollutant emissions
by 10% are reiterated and announced by State Council recently (firstly proposed in China’s Eleventh Five Year Plan), which
are incorporated into the assessment system of political achievements for provincial officials and enterprise leaders.
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
a
b
6.00E+16
Macao
Beijing
Shanghai
7.00E+16
1.4E+19
Guangzhou
Taipei
4.00E+16
1E+19
8E+18
3.00E+16
6E+18
2.00E+16
1.00E+16
0.00E+00
1990
1992
1994
1996
1998
2000
2002
Macao
Beijing
Shanghai
Guangzhou
6.00E+16
1.2E+19
5.00E+16
Taipei, Macao
Beijing, Shanghai, Guangzhou
Taipei
5.00E+16
4.00E+16
3.00E+16
4E+18
2.00E+16
2E+18
1.00E+16
0
0.00E+00
1990
2004
1992
1994
1996
1998
2000
2002
2004
Fig. 4. Emergy density (a, units: sej/ha) and per capita emergy used (b, unit: sej) of Beijing, Shanghai and Guangzhou from 1990 to 2005.
a
b
6.00E+16
0.70
Macao
Beijing
Shanghai
Guangzhou
5.00E+16
Taipei
8E+18
3.00E+16
6E+18
2.00E+16
1.00E+16
0.00E+00
1990
1992
1994
1996
1998
2000
2002
Beijing
Shanghai
Guangzhou
0.50
1E+19
4.00E+16
Macao
0.60
1.2E+19
Taipei, Macao
Beijing, Shanghai, Guangzhou
Taipei
1.4E+19
0.40
0.30
4E+18
0.20
2E+18
0.10
0
0.00
1990
2004
1992
1994
1996
1998
2000
2002
2004
Fig. 5. Proportions of local renewable (a) and self-sufficient ratios (b) of Beijing, Shanghai and Guangzhou from 1990 to 2005.
a
b
1.2
2.10E+23
Taipei
Macao
Beijing
Shanghai
Guangzhou
1.80E+23
Taipei
Macao
Beijing
Shanghai
Guangzhou
1.0
1.50E+23
0.8
1.20E+23
0.6
9.00E+22
0.4
6.00E+22
0.2
3.00E+22
0.0
0.00E+00
1990
1992
1994
1996
1998
2000
2002
2004
1990
1992
1994
1996
1998
2000
2002
2004
Fig. 6. Total waste output (a, unit:sej) and ratio of waste to total emergy used (b) of Beijing, Shanghai and Guangzhou from 1990 to 2005.
Possibly, all these decisions may bring forth profound influences on performance and sustainability of urban ecological economic system.
As to the indicator of non-renewable emergy/money ratio, the comparison showed different results. Shanghai had higher
non-renewable resource use efficiency considering the relatively low level of non-renewable resources consumption per unit
GDP during the concerned period. On the whole, Beijing had higher value of non-renewable emergy/money ratio than that of
Guangzhou. Nevertheless, the non-renewable emergy/money ratios have decreased for all these three cities of Beijing,
Shanghai and Guangzhou, during their urbanization processes mainly due to readjusting of industrial structure in urban
areas, see Fig. 7b.
Great efforts have been taken to improve the environmental quality and enhance the sustainability of the urban systems.
However, sustainable development must be more than merely ‘protecting’ the environment, which requires economic and
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L.X. Zhang et al. / Commun Nonlinear Sci Numer Simulat 14 (2009) 2827–2836
a
b
3.50E+12
1.40E+13
Beijing
Shanghai
Guangzhou
Beijing
3.00E+12
1.20E+13
2.50E+12
1.00E+13
2.00E+12
8.00E+12
1.50E+12
6.00E+12
1.00E+12
4.00E+12
5.00E+11
2.00E+12
0.00E+00
1990
Shanghai
Guangzhou
0.00E+00
1992
1994
1996
1998
2000
2002
2004
1990
1992
1994
1996
1998
2000
2002
2004
Fig. 7. Fuels and electricity emergy use per $ GDP (a, unit: sej/$) and non-renewable emergy/money ratio (b, unit: sej/$) of Beijing, Shanghai and Guangzhou
from 1990 to 2005.
social changes to reduce the need for environmental protection [39]. Nevertheless, the politico-economical changes, no matter macro-controls or strategic adjustments, will play an essential role in reshaping urban systems in China. Therefore, it is
no doubt that the current extensive deindustrialization and economic reconstructing in China will further affect the evolvement process of urban systems in many ways with regard to sustainability.
5. Conclusions
Systematic evaluation of urban systems is crucial to achieve the mega city’s goal of sustainable development. With emergy analysis based on ecological thermodynamics, comparative investigations have been made among typical mega cities of
Beijing, Shanghai and Guangzhou in the perspective of evolutionary process from 1990 to 2005. Three cities exhibited similar
overall trends of increase of total emergy use with annual fluctuations from 1990 to 2005. Although the mega cities of mainland China are intermediate in development level in the world, their life-support systems have become highly dependent on
non-renewable and purchased resources from outside. Concluded from the indicators such as emergy density, Shanghai
achieved highest levels of economic development and urbanization among the three case cities. However, the unfavorable
aspects associated with urban system of Shanghai were also very obvious, e.g., lower proportion of renewable resource use
and higher environmental pressure compared to those of Beijing and Guangzhou, which would definitely imperil its sustainability to some extent. Comparatively, Guangzhou has long term sustainability considering the fairly ideal indicators of locally renewable fraction used, per capita emergy used, energy consumption per unit GDP and the ratio of waste to renewable
emergy.
This paper presents a preliminary comparison analysis of typical mega cities and much more work needs to be done to
extend analysis to urban agglomerations (between or within) or to find out to what extent the deindustrialization process
affects the urban sustainability. In addition, it is still important to note that although emergy analysis offers powerful indices
for evaluating urban system performance, an integrated indicator system aimed at regional comparison of ecological competitive power of urban system remains a problem for the further research.
Acknowledgement
This work is supported by the National Basic Research Program of China (973 Program, Grant No. 2005CB724204) and
National Natural Science Foundation (Grant No. 40701023).
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