170
L. Chai et al.
4.1 Methodology
Using the idea of quantitative analysis, we studied the water depletion and
degradation of the entire life cycle of China’s coal-fired power plants.
First, we assess the water footprint during the life cycle and compiled Mixed-Unit
Input-Output (MUIO) tables. The first thing to note is that electricity prices are not
uniform, so in order to avoid the impact of price effects, this study uses the MUIO
model to evaluate CPG water quality. The formula can be written as
n
j=1
W F j =
n
j=1
n
i=1
W F i a i j +
n
j=1
DW j
where WF j indicates the WF of sector j; a ij indicates the demand of sector i by sector
j; DW j indicates the direct water use coefficient, referring to the direct Withdrawal
WF, the direct Blue WF, and the direct water pollutants discharge in sector j. The WF
and DW are measured in units of m
3 per kWh (electricity) and m
3 per Yuan (other
goods and services).
WF = DW ∗ (I − A)
−1
where WF is a vector, comprised of WFs of all sectors; DW is a direct water use
coefficient vector; A is a matrix of technical coefficients of intermediate inputs; I is
an identity matrix.
At the same time, we estimate three types of water footprints, namely Withdrawal water footprint, blue water footprint, and gray water footprint. The calculation
formula for the three footprints is as follows:
DW grey, p =
L p
C max, p − C nat, p
where DW grey,p (m
3 ) indicates the direct gray WF of pollutant p and; L p is the
discharge amount of pollutant p to the environment and is measured in a physical
unit of grams; C max,p is the maximum permissible concentration (gram per liter) for
pollutant p in the water body. C nat,p (gram per liter) is the concentration of pollutant
p in the natural water body, which is usually assumed to be zero.
The gray WF (m
3 per kWh) is determined by the maximum specific gray WF
among pollutants:
W F grey = maxmium
W F grey,1 , W F grey,2 , · · · , W F grey,p
By considering the differences in regional water shortages, we can better understand the impact of CPG on regional water resources. The Water Stress Index (WSI)
has been used by researchers to study the virtual water contained in electrical energy.
Its calculation formula is
L. Chai et al.
4.1 Methodology
Using the idea of quantitative analysis, we studied the water depletion and
degradation of the entire life cycle of China’s coal-fired power plants.
First, we assess the water footprint during the life cycle and compiled Mixed-Unit
Input-Output (MUIO) tables. The first thing to note is that electricity prices are not
uniform, so in order to avoid the impact of price effects, this study uses the MUIO
model to evaluate CPG water quality. The formula can be written as
n
j=1
W F j =
n
j=1
n
i=1
W F i a i j +
n
j=1
DW j
where WF j indicates the WF of sector j; a ij indicates the demand of sector i by sector
j; DW j indicates the direct water use coefficient, referring to the direct Withdrawal
WF, the direct Blue WF, and the direct water pollutants discharge in sector j. The WF
and DW are measured in units of m
3 per kWh (electricity) and m
3 per Yuan (other
goods and services).
WF = DW ∗ (I − A)
−1
where WF is a vector, comprised of WFs of all sectors; DW is a direct water use
coefficient vector; A is a matrix of technical coefficients of intermediate inputs; I is
an identity matrix.
At the same time, we estimate three types of water footprints, namely Withdrawal water footprint, blue water footprint, and gray water footprint. The calculation
formula for the three footprints is as follows:
DW grey, p =
L p
C max, p − C nat, p
where DW grey,p (m
3 ) indicates the direct gray WF of pollutant p and; L p is the
discharge amount of pollutant p to the environment and is measured in a physical
unit of grams; C max,p is the maximum permissible concentration (gram per liter) for
pollutant p in the water body. C nat,p (gram per liter) is the concentration of pollutant
p in the natural water body, which is usually assumed to be zero.
The gray WF (m
3 per kWh) is determined by the maximum specific gray WF
among pollutants:
W F grey = maxmium
W F grey,1 , W F grey,2 , · · · , W F grey,p
By considering the differences in regional water shortages, we can better understand the impact of CPG on regional water resources. The Water Stress Index (WSI)
has been used by researchers to study the virtual water contained in electrical energy.
Its calculation formula is