Environmental Engineering Reference
In-Depth Information
11.4. Estimating the Cost of Water Produced
The estimates of the cost of water that are given below are based on the life-cycle cost
analysis of the plant which includes capital, O&M and fuel costs. The total life-cycle cost,
TLC
, is the sum total of the capitals cost plus the present value of all future O&M annual
expenses:
TLC
=
C
tot
+
PW
(
F
) +
PW
(
OM
)
(80)
where,
C
tot
= total capital cost including engineering, installation and management costs,
PW
(
F
) = present worth of all annual fuel costs incurred throughout the lifetime of the
plant (for conventional plants),
PW
(
OM
) = present worth of all annual O&M expenses incurred throughout plant
lifetime.
The present worth of the annual fuel and O&M expenses are calculated from the
following expressions [5]
1
+
g
1
+
g
f
f
N
PW
(
F
)
=
F
(
)[
1
−
(
)
]
0
k
−
g
1
+
k
f
(81)
1
+
g
1
+
g
PW
(
OM
)
=
OM
(
om
)[
1
−
(
om
)
N
]
0
k
−
g
1
+
k
om
where
F
0
= fuel cost in the first year of operation, $
OM
o
= O&M cost in the first year of operation, $
g
f
= annual fuel escalation rate (assumed 0.03)
g
om
= annual O&M cost escalation rate (assumed 0.03)
k
= interest rate (assumed 0.08)
N
= plant lifetime, years (
N
= 20 years)
The cost of water,
c
w
, ($/m
3
) was calculated as follows
TLC
c
w
=
(82)
m
(
365
)
N
(
PF
)
d
where,
= desalination plant rated capacity, m
3
/day
m
d
PF
= plant factor (assumed 0.85)
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