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Power Plant Cooling--What are the trade-offs?
John S. MaulbetschMaulbetsch Consulting
December 7, 2005
2
Overview
Power plants use waterLargest use is for condenser coolingSome cooling systems use less water than othersTradeoffs are
• Amount of water used• Cost• Plant efficiency and output
3
The conclusions-in advance
Water conserving cooling systems are available at a price
Increased capital cost---500 MW plants0.4% to 12.5%
Increased cooling system power0.5 to 3.0 MW
Increased plant heat rates0.4 to 4.0 %
Increased power production costs1.9 to 4.9%
4
Plants
Discussion limited to…….
Plants with condenser cooling• Combined-cycle plants• Steam plants• Not simple cycle turbines or
reciprocating enginesNew plants• Not retrofits
5
Combined Cycle Plant
COMPRESSOR
GASTURBINE
FUEL
GENERATOR
GENERATOR
STEAMTURBINE
HRSG
EXHAUSTPUMP
CONDENSER
COMPRESSOR
GASTURBINE
FUEL
GENERATOR
GENERATOR
STEAMTURBINE
HRSG
EXHAUSTPUMP
CONDENSER
6
Steam Plant
COMPRESSOR
GASTURBINE
FUEL
GENERATOR
GENERATOR
STEAMTURBINE
HRSG
EXHAUSTPUMP
CONDENSER
COMPRESSOR
GASTURBINE
FUEL
GENERATOR
GENERATOR
STEAMTURBINE
HRSG
EXHAUSTPUMP
CONDENSER
Fuel
Boiler
7
Cooling systems
Commonly used• Once-through• Wet cooling• Dry cooling
Others• Hybrid (wet/dry) cooling• Spray enhanced dry cooling
8
Once-through
to HRSG
Cold CW
Hot CW
CW Pump(s)
Exhaust Steam
to HRSG
Cold CW
Hot CW
CW Pump(s)
Exhaust Steam
Water source—ocean, river, lake, etc
9
Wet Cooling Tower
Fans
Cooling Tower
BlowdownMakeup
Fans
Cooling Tower
BlowdownMakeup
Hot CW
Cold CW
Ambient air
from condenser
to condenser
10
Wet cooling tower
11
Air Cooled Condenser
Fans
to HRSG
Exhaust steam
Air Cooled Condenser
Fans
to HRSG
Exhaust steam
Air Cooled Condenser
Ambient air
from steam turbine
to boiler or HRSG
13
Water source
NaturalOcean Fresh surface waterGroundwater• potable• brackish
ReclaimedMunicipal dischargeAgricultural run-off
Cooling Water Taken In---500 MW Combined Cycle Plant
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
Once-through Wet Dry
Wat
er T
aken
In, g
pm
Cooling Water Consumption---500 MW Combined Cycle Plants
0
500
1,000
1,500
2,000
2,500
Once-through Wet Dry
Wat
er C
onsu
med
, gpm
?
Plant Capital Cost Capital Cost---500 MW Combined Cycle Plant
185,000,000
190,000,000
195,000,000
200,000,000
205,000,000
210,000,000
215,000,000
220,000,000
225,000,000
230,000,000
Once-through Wet Dry
Cooling System Type
Cap
tial C
ost,
$
Base+1.20 %
+12.5 %
Normalized Plant Cost Normalized Capital Cost---500 MW Combined Cycle
380
390
400
410
420
430
440
450
460
470
Once-through Wet Dry
Cooling System Type
Nor
mal
ized
Cap
ital C
ost,
$/kW
Base +1.2 %
+12.5 %
Design Heat Rate---500 MW Combined Cycle Plant
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Once-through Wet Dry
Cooling System Type
Hea
t Rat
e, B
tu/k
Wh
Base
+0.37 %
+0.71%
Hot Day OutputHot Day Capacity Loss---500 MW Combined Cycle Plants(Includes Effect on Combustion Turbines)
0
10
20
30
40
50
60
Once-through Wet Dry
Cooling System Type
Hot
Day
Cap
acity
Los
s, M
W
Cooling Water Taken In---500 MW Steam Plant
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
Once-through Wet Dry
Coo
ling
Wat
er T
aken
In, g
pm
Cooling Water Consumed---500 MW Steam Plant
0
500
1,000
1,500
2,000
2,500
3,000
3,500
Once-through Wet Dry
Wat
er C
onsu
med
, gpm
?
Capital Cost---500 MW Steam Plant
280,000,000
290,000,000
300,000,000
310,000,000
320,000,000
330,000,000
340,000,000
350,000,000
Once-through Wet Dry
Cooling System Type
Cap
tial C
ost,
$
Base +.43 %
+12.6 %
Normalized Capital Cost---500 MW Steam Plant
560
580
600
620
640
660
680
700
720
Once-through Wet DryCooling System Type
Nor
mal
ized
Cap
ital C
ost,
$/kW
Base +.47 %
+12.8 %
Design Heat Rate---500 MW Steam Plant
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
Once-through Wet Dry
Cooling System Type
Hea
t Rat
e, B
tu/k
Wh
Base +3.7 %
+4.2%
Hot Day Heat Rate Increase---500 MW Steam Plants
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
Once-through Wet DryCooling System Type
Hea
t Rat
e In
crea
se, %
Power costsPower for Cooling System Pumps and Fans
0
1,000
2,000
3,000
4,000
5,000
6,000
Once-through Wet Dry
Cooling System Type
Coo
ling
Sys
tem
Pow
er, k
W
Combined Cycle Steam
27
Maintenance Costs
Labor, chemicals and equipment
Highly site-specific
Estimated at 1 to 3% of cooling system capital cost
10’s to 100’s of k$ per year---negligible in comparison to other cost items
Levelized Cost Components for Sample Combined-Cycle Natural Gas Power Plant
Fuel Costs75%
Ins urance & Ad Valorem Costs
2%
Corporate Taxe s (w/Credits)
4%
Fixed O&M Costs1%
Capital & Financing -
Construction16%
Var iable O&M2%
Levelized Cost Components By Percent
Production Cost Breakdown---Dry Cooling500 MW Combined-Cycle Plant
Capital10.86%
Fuel88.16%
Cooling power0.78%
Cooling Maintenance
0.19%
Cost of Electricity---500 MW Combined-Cycle Plant
0
5
10
15
20
25
30
35
40
45
50
Once through Wet DryType of Cooling System
Cos
t of E
lect
rici
ty, $
/MW
h
Cost due to Capital Cost due to fuel
Base +1.86 % +3.30 %
Annualization factor--0.075; Cost of fuel--$6/MMBtu; Capacity factor--8,100 hours/year
43.05 $/MWh 43.85 $/MWh 44.47 $/MWh
Cost of Electricity---500 MW Steam Plant
0
10
20
30
40
50
60
Once through Wet DryType of Cooling System
Cos
t of E
lect
rici
ty, $
/MW
h
Cost due to Capital Cost due to fuel
Base +3.08 % +4.86 %
Annualization factor--0.075; Cost of fuel--$6/MMBtu; Capacity factor--8,100 hours/year
52.60 $/MWh 54.22 $/MWh 55.16 $/MWh
32
Additional considerations
Benefit of “a little bit” of water– Hybrid (wet/dry) systems – Spray enhancement
33
Hybrid (wet/dry) system
Tucuman 450 MW Combined Cycle (Argentina)PAC SYSTEM®
(Air Cooled Condenser & Wet Cooling System)
35
Hybrid System Cost Estimate
Capital Cost of Cooling System
Water Conservationx
Plume Abatement
x
Hybrid System Range of Water Use
0% 100% (All Wet)15% 85%
36
Spray enhancement
Spray water into inlet air stream of air-cooled condenserLow capital cost approachLow annual water useReduce inlet temperature by 5 to 10 FRestore “hot day” capacity loss
38
Summary—Combined-Cycle Plants
Once-through Wet tower Dry cooling HybridPlant Cost
Capital, $ 198,800,000 201,200,000 223,700,000 VariableNormalized Capital Cost, $/kW 405.7 410.6 456.5 Variable
PerformanceCooling Sysem Power, kW 2,075 2,720 2,980 VariableDesign Heat Rate, Btu/kWh 6,549 6,573 2,980 Close to dry
Hot day Capacity Loss, MW Base 2.7 26.1 Close to wet
WaterWater taken in, gpm 132,410 2,290 0 (for cooling) 20 - 30% of wet
Water consumed, gpm De minimis ?? 2,048 0 (for cooling) "
Cooling SystemItems for comparison
500 MW Combined-Cycle Plant
39
Summary—Steam Plants
Once-through Wet tower Dry cooling HybridPlant Cost
Capital, $ 302,900,000 304,200,000 341,300,000 VariableNormalized Capital Cost, $/kW 405.7 410.6 456.5 Variable
PerformanceCooling Sysem Power, kW 2,021 4,580 5,095 VariableDesign Heat Rate, Btu/kWh 7,800 8,088 8,129 Close to dry
Hot day Heat Rate, Btu/kWh Base 0.48% 8.62% Close to wet
WaterWater taken in, gpm 180,500 3,680 0 (for cooling) 20 - 30% of wet
Water consumed, gpm De minimis ?? 2,940 0 (for cooling) "
Items for comparison Cooling System500 MW Steam Plant