Increasing Resilience of Power Generation to Water Shortages during Drought

Bridget Scanlon, Robert Reedy, Ian Duncan, Alex Sun, and Michael Young, and William F. Mullican

Bureau of Economic Geology, Jackson School of Geosciences

Differences between Energy and Water Systems

• Generation: – Can generate electricity…cannot generate

water

• Storage: – Can store water….cannot store electricity

• Transport: – Can transport electricity….cannot readily transport

water

• Out of phase behavior of water demand for electricity and water supply

Limited Connection between ERCOT and Other Grids

Basic Questions

• How much water does electricity generation use?

• What controls water requirements for electricity generation?

• How vulnerable are water sources for electricity generation to drought?

• How can we make the system more drought resilient?

Water Withdrawal

33%

18%

5%

41%

Kenny et al., 2009; USGS

Water Consumption (2010)

56%

27%

10% 4% 2% 2%

TWDB 2012 State Water Plan

Basic Questions

• How much water does electricity generation use?

• What controls water requirements for electricity generation?

• How vulnerable are these water sources?

• How can we make the system more drought resilient?

Controls on Water Usage by Power Plants

• Fuel type: nuclear fuel, coal, natural gas

• Generator type: steam turbine, gas turbine, combined cycle (steam + gas)

• Cooling system: open loop or once through, closed loop (recirculating ponds or cooling towers)

• Fuels often associated with generator types – TX Coal and nuclear plants…steam turbine

– TX natural gas…steam, gas, and combined cycle

Water Withdrawals by Fuel Type and Cooling System (2010 data)

Cooling Type

OT: once through; NG, natural gas

Water Withdrawal and Consumption by Fuel Type and Cooling System

Inverse relationship between water withdrawal and water consumption

Cooling Pond

Generator

Turbine

Condenser Heat Source

Boiler

Electricity

Boiler Water

System Boundary

Diversion (river or

lake)

Rainfall Evap.

Withdrawal

Discharge

Steam

Run-on

Recirculating Pond Steam Turbine

Large withdrawal Low consumption

Water Use by Generation Type

• Steam turbine • Gas turbine (~ 0.05 gal/kWh) • Combined cycle (gas and steam) • Cogeneration …. Combined heat and power

• Coal and nuclear plants in Texas….all steam

turbine • Natural gas…steam and gas turbines and

combined cycle (combined cycle water consumption = 1/3rd that of steam turbine)

Basic Questions

• How much water does electricity generation use?

• What controls water requirements for electricity generation?

• How vulnerable are water sources for electricity generation to drought?

• How can we make the system more drought resilient?

Power Plant Water Source

SW: 77% GW: 9% WW: 8% Muni: 5% Salt W: 1%

Consumption

30% Reduction in Per Capita Reservoir Storage since 1980s

Basic Questions

• How much water does electricity generation use?

• What controls water requirements for electricity generation?

• How vulnerable are water sources for electricity generation to drought?

• How can we make the system more drought resilient?

Reducing Drought Vulnerability

• Reduce demand for energy and water, increase supply of water, store more water

• Should we focus on withdrawals or consumption?

• How can we make power plants less water intensive?

• Could we use different sources of water?

• What about other ways of storing water besides surface reservoirs?

Water Withdrawal and Consumption by Fuel Type and Cooling System

Inverse relationship between water withdrawal and water consumption

How can we make power plants less water intensive?

• Water withdrawals: – Cooling towers – Dry cooling

• Water consumption: – Combined cycle natural gas – Gas turbines – Dry cooling

• Energy penalties and equivalent cost of water saved – Considerable energy penalties with dry cooling and

large capital costs

Conjunctive Use of Groundwater with Surface Water

Store Water in Aquifers

• Aquifer storage and recovery

• Store excess surface water in aquifers

• Allows adaptation to climate extremes…floods and droughts

• Power plants with take or pay contracts …. store unused water in aquifers

Basic Questions

• How much water does electricity generation use?

• What controls water requirements for electricity generation?

• How vulnerable are water sources for electricity generation to drought?

• How can we make the system more drought resilient?

Reservoir Storage

• $$ cost • Climate variability/change • Water availability SW GW FW salt water • Ecosystems fish • Energy demand • Fuel (availability Price) • Generator type • Cooling systems • Regulations • Time

Fuel Type

37

46

10

7.00.3

Coal

Natural Gas

Nuclear

Renewables

Other

TX

44

24

20

10

1.4

US

Methods

• Estimated water usage for 2010 using EIA, TWDB, and TCEQ data

• Evaluated controls on water usage: fuel, generator, cooling system

• Examined power plant water usage relative to reliability of water supplies (2011 drought)

• Future projections

-

10

20

30

40

50

60

70

80

90

< 0.1 0.1 - 0.5 0.5 - 1.0 1.0 - 2.5 2.5 - 5.0 5.0 - 21.1

Nu

mb

er o

f P

ow

er P

lan

ts

2010 Net Generation (Million MWh)

Biopower

Hydroelectric

Oil

NG

Nuclear

Coal

-

10

20

30

40

50

60

70

80

90

< 0.1 0.1 - 0.5 0.5 - 1.0 1.0 - 2.5 2.5 - 5.0 5.0 - 21.1

Nu

mb

er o

f P

ow

er P

lan

ts

2010 Net Generation (Million MWh)

ST

GT

CT/CA

IC

HY

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

ly n

et

genera

tion (

MW

h)

NG

Coal

Nuclear

Wind

Other

Water Usage for Power Plants 2010

• Consumption 3% of state water 0.5 maf 18 maf other consumers

• Withdrawals 22 maf

Drought

• Water

• T intake

• T discharge

Drought Proof

• Water quantity versus temperature issues • Dry cooling • Desalinate seawater • Gas turbines • Combined cycle • Cooling towers vs open loop systems • Wind solar • Conserve energy conserve water • Surface water groundwater conjunctive use • ASR Brackish water sea water • Retrofits new plants retirements

Generator

Turbine

Discharge Condenser Heat Source

Boiler

Electricity

Cooling Water

Warm Cooling Water

Steam

Boiler Water

System Boundary

Rainfall Evap.

River

Withdrawal

Once-Through Open-Loop Cooling Steam Turbine

Large withdrawal Low consumption

Generator

Turbine

Condenser Heat Source

Boiler

Electricity

Steam

Electricity Generation Using a Steam Turbine

Cooling Pond

Generator

Turbine

Condenser Heat Source

Boiler

Electricity

Boiler Water

System Boundary

Diversion (river or

lake)

Rainfall Evap.

Withdrawal

Discharge

Steam

Run-on

Recirculating Pond Steam Turbine

Large withdrawal Low consumption

Cooling Pond

Generator

Turbine

Condenser Heat Source

Boiler

Electricity

Boiler Water

System Boundary

Evap.

Diversion (river or

lake)

Discharge Withdrawal

Cooling Tower

Blowdown

Rainfall

Steam

Cooling Tower

Steam Turbine

Low withdrawal Higher consumption

Increasing Resilience of Power Generation to Water Shortages

during Drought

Bridget Scanlon, Robert Reedy, Ian Duncan, Alex Sun, and Michael Young, and William F.

Mullican

Bureau of Economic Geology, Jackson School of Geosciences, Univ. of Texas at Austin