Emergy Comparison of Typical Coastal Urban Ecosystems in China
Table 1
Calculation of emergy indicators of each city [25].
Indicators
Representative symbol
Calculation formula
Shenzhen
Dalian
Ningbo
Qingdao
Xiamen
Indicator meanings
Emergy self-sufficiency rate (%)
ESR
(R + N)/U
50.12
85.26
90.26
67.78
37.60
Measure system development self-sufficiency
Emergy yield rate
EYR
(R + N + IMP)/IMP
2.00
6.78
10.27
3.10
1.60
Reflect the foreign trade gains and losses of the eco-economic system
Emergy usage per person (1017 sej/person)
EUPP
U/P
2.18
3.26
5.33
0.79
1.21
Reflect the living standard and quality of the population
Emergy density (1013 sej/m2)
ED
U/A
2.78
1.54
15.94
0.65
2.85
System development strength and intensity
Emergy money rate (1012 sej/$)
EMR
U/GNP
8.19
18.66
21.80
4.49
7.50
Reflect system technological progress and economic modernization
Emergy input rate
EIR
IMP/(R + N)
1.00
0.17
0.11
0.48
1.66
Reflect the harmonious degree of system economic development and resource and environmental pressure
Environment load rate
ELR
(N + IMP)/R
20.52
29.21
33.12
6.29
1.72
Measure the pressure of human social and economic activities on resources and environment
Emergy waste rate (10−3)
EWR
W/R
3.18
6.51
5.62
3.69
0.18
Measure the pressure of waste on the environment
Emergy sustainable index
ESI
EYR/ELR
0.10
0.23
0.31
0.49
0.93
Measure the sustainability of the system
Note. R: renewable energy; N: nonrenewable energy; IMP: input energy value; U: total energy value usage (U = R + N + IMP); GNP: gross domestic product; P: total population at the end of the year; A: the total area.
