NETL - cooling water

A Solution to Water Crisis in Energy Production:

Feasibility of Using Impaired Waters for Coal Fired

Power Plant Cooling

Heng Li, Shih-Hsiang Chien, Radisav Vidic

University of Pittsburgh

Ming-Kai Hsieh, David Dzombak

Carnegie Mellon University

OVERVIEW

• Water-Energy Nexus

• Water requirements in thermoelectric power

production

• Alternative waters for power plant cooling

• Research materials and methods

• Results and discussions

• Summary

WATER-ENERGY NEXUS

Current Approach:

• Planning for future electricity production without considering how water requirements will be met over time, and

• Planning for future water resources with the assumption that electricity will be readily availability

Energy-water relationship:

• Need electricity to produce water

• Need water to produce electricity

Water Use in Thermoelectric Power Plants

Water vapor

Water vapor

Water-Intensive

ProcessesSteam cycle Cooling water

Condenser

Cooling tower

Heat

Source

Boiler

feedwater

make-up

Cooling

tower

make-up

Process

water

make-up

Cooling water

blowdown

Raw water source (river, lake, ocean, well, municipal system, etc.)

Other Cooling

Requirements

Steam

Turbine

Additional

Processes

Wet Solid

Waste

THERMOELECTRIC POWER GENERATION

AND WATER

U.S. Freshwater Withdrawal (2000)

Thermoelectric, 39%

Public Supply, 13%Domestic, 1%

Irrigation, 40%

Livestock, 1%

Aquaculture, 1%

Industrial, 5%

Mining, 1%

U.S. Freshwater Consumption (1995)

Thermoelectric, 3%

Mining, 1%

Industrial, 3%

Livestock, 3%

Irrigation, 81%

Domestic, 6%

Commercial, 1%

Sources: USGS, 1998, 2004

• 2000 thermoelectric water

requirements:

– Withdrawal: ~ 136 BGD

– Consumption: ~ 4 BGD

• Thermoelectric power plants compete

with other use sectors.

LIMITATIONS IN WATER AVAILABILITY FOR

POWER PLANT COOLING

TX

CA

MT

AZ

ID

NV

NM

CO

IL

OR

UT

KS

WY

IANE

SD

MN

ND

OK

FL

WI

MO

AL

WA

GA

AR

LA

MI

IN

PA

NY

NC

MS

TN

KYVA

OH

SC

ME

WV

MI VTNH

MD

NJ

MA

CT

DE

RI

Legend

shortage

Statewide

Regional

Local

None

No response or uncertain

Survey ResponsesExtent of State Shortages Likely over the Next Decade

under Average Water Conditions

AK

HI

HI

HI

HI

HI

TX

CA

MT

AZ

ID

NV

NM

CO

IL

OR

UT

KS

WY

IANE

SD

MN

ND

OK

FL

WI

MO

AL

WA

GA

AR

LA

MI

IN

PA

NY

NC

MS

TN

KYVA

OH

SC

ME

WV

MI VTNH

MD

NJ

MA

CT

DE

RI

Legend

shortage

Statewide

Regional

Local

None

No response or uncertain

Survey ResponsesExtent of State Shortages Likely over the Next Decade

under Average Water Conditions

AK

HI

HI

HI

HI

HI

TX

CA

MT

AZ

ID

NV

NM

CO

IL

OR

UT

KS

WY

IANE

SD

MN

ND

OK

FL

WI

MO

AL

WA

GA

AR

LA

MI

IN

PA

NY

NC

MS

TN

KYVA

OH

SC

ME

WV

MI VTNH

MD

NJ

MA

CT

DE

RI

Legend

shortage

Statewide

Regional

Local

None

No response or uncertain

Survey ResponsesExtent of State Shortages Likely over the Next Decade

under Average Water Conditions

AK

HI

HI

HI

HI

HI

TX

CA

MT

AZ

ID

NV

NM

CO

IL

OR

UT

KS

WY

IANE

SD

MN

ND

OK

FL

WI

MO

AL

WA

GA

AR

LA

MI

IN

PA

NY

NC

MS

TN

KYVA

OH

SC

ME

WV

MI VTNH

MD

NJ

MA

CT

DE

RI

Legend

shortage

Statewide

Regional

Local

None

No response or uncertain

Survey ResponsesExtent of State Shortages Likely over the Next Decade

under Average Water Conditions

AK

HI

HI

HI

HI

HI

Source: US Government Accountability Office2003

Source: Roy et al., (2003) A Survey of Water

Use and Sustainability in the United States with

a Focus on Power Generation. EPRI

Expected Cooling Water Shortage in 2025

POSSIBLE ALTERNATIVE SOURCES OF

COOLING WATER

Municipal

Wastewater

Abandoned Mine Drainage

Ash Pond Water

REUSE OF MUNICIPAL WASTEWATER

IN THE COOLING SYSTEMS OF

THERMOELECTRIC POWER PLANTS

• 11.4 trillion gallons of municipal wastewater

collected and treated annually in U.S.

• Experience with use of treated municipal

water for power plant cooling in arid west;

e.g., Burbank, Las Vegas, Phoenix

• Significant additional treatment beyond

secondary treatment (e.g., clarification,

filtration, N and P removal)

GIS-based tool developed to assess availability of

secondary effluent from publicly owned treatment works

(17864 POTWs in lower 48 states).

INVENTORY OF AVAILABLE MUNICIPAL

WASTEWATER

INVENTORY OF WATER NEEDS

• 110 proposed power plants from EIA annual report 2007

• U.S. is divided into major NERC regions

POWER PLANTS WITH SUFFICIENT MUNICIPAL

WASTEWATER FOR COOLING

81

92

49

76

0

20

40

60

80

100

10 25

Pe

rce

nta

ge

, %

Coverage radius, mile

Proposed Power Plants Existing Power Plants

SUMMARY – WASTEWATER AVAILABILITY

POTWs located within 10 and 25 mile radius from

the proposed power plants can satisfy 81% and

92% of proposed and 49% and 76% of existing

power plant cooling water needs, respectively.

On average, one fairly large POTW can

completely satisfy the cooling water demand for

each of these power plants.

KEY TECHNICAL CHALLENGES WITH

THE USE OF IMPAIRED WATERS

• Precipitation and scaling

• Accelerated corrosion

• Biomass growth

CORROSION AND SCALING CONTROL

Categories AgentsConsideration for

Study

Corrosion control

Inorganic-anodic

Chromate No

Nitrite No

Nitrate No

Molybdate No

Orthophosphate Yes

Silicates No

Inorganic-cathodicZinc Yes

Polyphosphate Yes

Organic inhibitorsAzoles Yes

Amines and fatty polyamines No

Scaling and fouling control

Chelant Glucoheptonates No

Traditional inhibitors

Amines and fatty polyamines No

Phosphonates Yes

Phosphate esters No

Polymer

Polycarboxylic acid (PCA) No

Polyacrylates (PAA) Yes

Polymaleic acid (PMA) Yes

Natural dispersantsLigno-sulfonates No

Tannins No

Bench-scale Water Recirculating System:

Scaling and Biofouling

P

Hot plate

Flo

w m

ete

r

Valve

Pump

Electrode holder

Synthetic

wastewater

PTPotentiostat Electrode

Recirculating flow

Bench-scale Water Recirculating System:

Corrosion Studies

CORROSION CRITERIA FOR

COMMONLY USED ALLOYS

1 MPY

3 MPY

5 MPY

10 MPY

0.1 MPY

0.2 MPY

0.3 MPY

0.5 MPY

Excellent

Good

Fair

Poor

Unacceptable

Mild steel piping Copper and copper alloys

Source: Puckorius, (2003) Cooling Water System

Corrosion Guidelines. Process Cooling & Equipment.

PILOT SCALE COOLING TOWERS

Franklin Township Municipal

Sanitary Authority, Murrysville, PA

Pilot-Scale Water Recirculating System

Coupon/Electrode rackBiocide tank Heater

Chemical Treatment Programs for Secondary

Treated Municipal Wastewater

Target chemical agent conc. (ppm)

Agents Tower

A1

Tower

B1

Tower

C1

Tower

A2

Tower

B2

TTA 2 1 2 2 0

TKPP 10 0 10 0 0

PMA 10 0 20 10 0

PBTC 5 0 10 0 0

MCA 1-2 1-2 1-2 3-4 3-4

Corrosion Rates in Cooling Towers

Average corrosion rate category

Metal alloys Tower A1 Tower B1 Tower C1 Tower A2 Tower B2

Mild steel(21-day avg.)

Mild steel(last 5 days avg.)

Copper(21-day avg.)

Copper-nickel(21-day avg.)

excellent good fair poor unaccep.

Scaling Rates in Cooling Towers

0

5

10

15

20

25

30

0 5 10 15 20 25

De

po

sit

s (

mg

)

Immersion time (day)

Tower C (PMA-PBTC 20/10ppm)

Tower B (blank)

Tower A (PMA-PBTC 10/5ppm)

98

7

0 1 2 3 4 5 6

Disc number

0%

25%

50%

75%

100%

7 8 9

Re

lati

ve

am

ou

nt

Coupon disc number

unburnable mass burned mass

SUMMARY: SCALING AND CORROSION

• Several scale inhibitors were effective in the absence of disinfectants

• Phosphate, either present in the makeup water or added as corrosion inhibitor, worsened scaling

• Ammonia could accelerate corrosion and mitigate scaling, but was stripped in the cooling tower

• In general, except for aluminum (pitting in all situations), corrosion rates of alloys were within acceptable range

SUMMARY: BIOFOULING

• Addition of chlorine impaired the

effectiveness of the antiscalants and

accelerated corrosion

• Chloramine was an effective biocide and much less corrosive than chlorine

• Continuous monochloramine dosing to achieve 3 – 4 ppm as Cl2 successfully inhibited biomass growth with planktonicheterotrophic plate count under 104

CFU/ml and sessile heterotrophic plate count under 104 CFU/cm2

ADDITIONAL ISSUES WITH THE USE

OF IMPAIRED WATERS

• Pretreatment before use vs. extensive chemical

addition to the cooling tower

• LCA of the alternatives

• Regulatory issues

• Social issues

Acknowledgement

U.S. DOE – National Energy Technology Laboratory

“Reuse of Treated Internal or External Wastewaters in the Cooling

Systems of Coal-based Thermoelectric Power Plants”

(Grant # DE-FC26-06NT42722)

Jim Brucker and Gene Greco

Franklin Township Municipal Sanitary Authority (Murrysville, PA)