Power Plant Cooling --What are the trade-offs?...38 Summary— Combined-Cycle Plants Once-through Wet tower Dry cooling Hybrid Plant Cost Capital, $ 198,800,000 201,200,000 223,700,000

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


Fans

to HRSG

Exhaust steam


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


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


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


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


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


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


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


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


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


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


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

Documents

Power Plant Cooling --What are the trade-offs?...38 Summary— Combined-Cycle Plants Once-through Wet tower Dry cooling Hybrid Plant Cost Capital, $ 198,800,000 201,200,000 223,700,000