Study Results

Drought Scenario Study

This slide deck contains results from the 2011 TEPPC Study Program. This study shows the impact in the interconection of increased thermal plant forced outages and decreased hydro caused by drought conditions.

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• Central Question: What impact do changes in thermal plant operation and hydro generation availability have on transmission utilization, production cost, and the ability of the Western Interconnection to continue serving its load obligation?

• Change to starting input assumptions:o Loads – Peak demand increased to reflect higher

temperatures in drought year (inputs provided by NREL)o Transmission System – Noneo Generation – Low hydro (2001) data used; increased

thermal plant forced outages modeled (inputs provided by Argonne National Laboratory)

• Results follow…

2022 PC7 WGA Drought Study

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• 1977 western drought• Selected due to severity and coincidence within multiple basins• Defined by USGS HUC-2 Basin flows

Drought Condition Selected for Study

Presented by Chris Harto (ANL) on Nov 15 DWG call

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Modeling of Hydro Generation

Presented by Chris Harto on Nov 15 DWG call

Miss

ouri

TX Gulf

Rio Gra

nde

Upper

CO

Lower

Co

Great

Bas

in

Pacific

NW

Califo

rnia

0.000

0.050

0.100

0.150

0.200

0.250

Worst Case Loss of Generation 1977 Scenario

Thermo

Hydro

Fra

ctio

n o

f to

tal

gen

erat

ion

lo

st (

MW

h

bas

is)

Miss

ouri

TX Gulf

Rio Gra

nde

Upper

CO

Lower

Co

Great

Bas

in

Pacific

NW

Califo

rnia

0.000

0.050

0.100

0.150

0.200

0.250

Worst Case Loss of Generation 2001 Scenario

Thermo

Hydro

Fra

ctio

n o

f to

tal

gen

erat

ion

lo

st (

MW

h

bas

is)

Hydroelectric Generation :Same as TEPPC low flow hydro case (2001)

Differences:• Slight overestimation of impact

to Pacific NW and CA• Slight underestimation for Great

Basin and Lower CO

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• “At-risk” thermal plants identified based on their dependence upon surface water for cooling

• Impacted plants identified in sub-basins where flow under drought was less than 50% of normal flowo List of impacted plants in WECC will not be reported

since no plant-specific analysis of drought mitigation plans was conducted

• Impact to “at-risk” plants modeled as increased forced outage rates

Impact of Drought on Thermal Plants

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• Based on estimate of lost generation• Calculated using EIA data for impacted

plants• Lost generation proportional to the loss of

flow relative to the minimum of the average basin flow or 2010 water demand

• Lost generation was allocated monthly based on deviation from normal flow in that month relative to other months

Determining Increased Forced Outage Rates (Down Days)

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Overview of Lost Thermoelectric Generation

Basin Lower Colorado CaliforniaLost Generation (MWh) 6,470,000 4,670,000

at risk capacity under 50% historical flow (MW) 1,908 1,791

at risk with WECC equivalent found (MW) 1,837 1460*

Fraction of at risk capacity found in WECC database 0.96 0.82average down days 147 133day/month 12.2 11.1*Includes 407 MW of CA geothermal at risk

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Monthly Variability in Lost Generation

  Lower Colorado California

  Flow RatioLost Generation

MWh Down Days Flow RatioLost Generation

MWh Down Days

JAN 0.3649 1,097,515 24.9 0.2632 652,592 18.6

FEB 0.2935 1,220,901 27.7 0.2538 660,918 18.9

MAR 0.5556 767,967 17.4 0.2783 639,218 18.2

APR 0.6923 531,736 12.1 0.292 627,083 17.9

MAY 0.6667 575,975 13.1 0.3013 618,846 17.7

JUN 0.8182 314,168 7.1 0.4333 501,932 14.3

JUL 1.125 0 0.0 0.6183 338,076 9.6

AUG 0.931 119,239 2.7 0.6788 284,490 8.1

SEP 0.8571 246,945 5.6 0.6592 301,850 8.6

OCT 0.878 210,828 4.8 0.6438 315,490 9.0

NOV 0.4737 909,498 20.6 1.2627 0 0.0

DEC 0.6 691,239 15.7 1.0427 0 0.0

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• Forced outage rates modified to reflect increased “down days” for all impacted plants within a basin

All impacted plants assumed to be down the same number of days in a given month

• Overlap allowed with scheduled maintenance

Modifying Forced Outage Rates

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• Developed by NREL• Basis for demand changes: ‘99 California

Energy Commission Study titled High Temperatures & Electricity Demand: An Assessment of Supply Adequacy in California, Trends & Outlooko Study provided an estimate for the change in

peak demand for 17 areas in the WSCC for two high temperature scenarios (1-in-5 and 1-in-40 probability)

Impact of Drought on Demand

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1. Match 17 WSCC areas to 2022 TEPPC load bubbles

2. Identify hottest month for each load area in 1977 (Drought year)

3. Increase peak demand for this month only by the 1-in-40 % change value reported for the WSCC area in the CEC studyo Monthly energy was increased by ½ of the peak

demand change to preserve the demand shape

Peak Load Adjustment Method

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Peak Load Adjustments Summary

TEPPC Area

WSCC Area (Table I-10 in CEC 1999 Study)

Water Resource Region (HUC 2)

StateHottest Month in 1977

Change in Peak to Apply to PROMOD (from the "1-in-40 Probability" Scenario of the 1999 CEC Study)

AESO Alberta Pacific Northwest MT JUL 0.50%APS Arizona Lower Colorado AZ JUL 5.30%AVA Northwest Pacific Northwest WA AUG 1.10%BCTC BCHA Pacific Northwest WA AUG 0.80%BPA Northwest Pacific Northwest OR AUG 1.10%CFE CFE California CA AUG 1.30%CHPD Northwest Pacific Northwest WA AUG 1.10%DOPD Northwest Pacific Northwest WA AUG 1.10%EPE NewMexico Texas-Gulf TX AUG 4.50%FAR EAST ID-SPP Pacific Northwest ID AUG 0.70%GCPD Northwest Pacific Northwest WA AUG 1.10%IID IID California CA AUG 8.80%LDWP LADWP California CA AUG 6.90%MAGIC VLY ID-SPP Pacific Northwest ID AUG 0.70%NEVP SoNevada Great Basin NV JUL 9.00%NWMT Wyoming Missouri MT JUL 0.20%PACE_ID ID-SPP Pacific Northwest ID AUG 0.70%PACE_UT Utah Great Basin UT JUL 0.20%PACE_WY Wyoming Missouri WY JUL 0.20%PACW Northwest Pacific Northwest OR AUG 1.10%PG&E BAY CSF California CA AUG 0.00%PG&E VLY CNorth California CA AUG 9.60%PGN Northwest Pacific Northwest OR AUG 1.10%PNM NewMexico Rio Grande NM JUL 4.50%PSC Colorado Upper Colorado CO JUL 1.80%PSE Northwest Pacific Northwest WA AUG 1.10%SCE CSCE California CA AUG 8.80%SCL Northwest Pacific Northwest WA AUG 1.10%SDGE CSDGE California CA AUG 0.70%SMUD CNorth California CA AUG 9.60%SPP CNorth Great Basin NV JUL 9.60%SRP Arizona Lower Colorado AZ JUL 5.30%TEP Arizona Lower Colorado AZ JUL 5.30%TIDC CNorth California CA AUG 9.60%TPWR Northwest Pacific Northwest WA AUG 1.10%TREAS VLY ID-SPP Pacific Northwest ID AUG 0.70%WACM Colorado Upper Colorado CO JUL 1.80%WALC Arizona Lower Colorado AZ JUL 5.30%WAUW Wyoming Missouri MT JUL 0.20%

2022 PC1 WECC-Wide Coincident Peak Demand: 172,082 MW

2022 PC7 Adjusted Coincident Peak Demand: 176,080 MW (2.3% inc.)

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Conventional Hydro

Pumped Storage

Steam - Coal

Steam - Other

Nuclear

Combined Cycle

Combustion Turbine

Cogeneration

IC

Negative Bus Load

Biomass RPS

Geothermal

Small Hydro RPS

Solar

Wind

(40,000,000) (20,000,000) 0 20,000,000 40,000,000

Annual Energy Difference: 2022 PC1 Common Case vs. 2022 PC7 WGA Drought

GWh

2022 WGA Drought – Changes in Total Annual Generation vs. Common Case

GWh

Low Hydro Results

Other Results (see TEPPC Glossary for definitions)

PC1 PC7 DifferenceDump Energy (MWh) 397,104 298,827 (98,277) -24.748%Emergency Energy (MWh) 2,676 3,063 386 14.436%

CO2 Emissions (MMetricTons) 359 373 14 3.936%

CO2 Adder ($/metric ton) 0.000 0.000

Variable Production Cost (thermal units excl DSM)

CO2 Adder (Total M$) 0 0 0 0.000%

Other Variable Costs (M$) 14,851 16,262 1,411 9.502%

Total Var. Prod. Cost (M$) 14,851 16,262 1,411 9.502%

Only an increase in areas with emergency in the Common Case (CFE, AESO)

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2022 WGA Drought – Changes in Total Annual Generation vs. Low Hydro

Conventional Hydro

Pumped Storage

Steam - Coal

Steam - Other

Nuclear

Combined Cycle

Combustion Turbine

Cogeneration

IC

Negative Bus Load

Biomass RPS

Geothermal

Small Hydro RPS

Solar

Wind

(4,000,000) (2,000,000) 0 2,000,000 4,000,000 6,000,000

Annual Energy Difference: 2022 PC1-2 Low Hydro Sensitivity vs. 2022 PC7 WGA Drought

GWhGWh

Other Results (see TEPPC Glossary for definitions)

PC1-2 PC7 DifferenceDump Energy (MWh) 315,155 298,827 (16,327) -5.181%Emergency Energy (MWh) 2,825 3,063 237 8.403%

CO2 Emissions (MMetricTons) 374 373 (1) -0.170%

CO2 Adder ($/metric ton) 0.000 0.000

Variable Production Cost (thermal units excl DSM)

CO2 Adder (Total M$) 0 0 0 0.000%

Other Variable Costs (M$) 16,064 16,262 198 1.233%

Total Var. Prod. Cost (M$) 16,064 16,262 198 1.233%

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2022 WGA Drought – Changes in Generation by State vs. Common Case

Alberta

Arizon

a

British

Colu

mbia

Califo

rnia

Colora

do

Idah

o

Mex

ico

Mon

tana

Nevad

a

New M

exico

Orego

n

South

Dak

ota

Texas

Utah

Was

hingt

on

Wyo

ming

-20,000,000

-15,000,000

-10,000,000

-5,000,000

0

5,000,000

10,000,000

15,000,000

20,000,000

Annual Energy Difference: 2022 PC1 Common Case vs. 2022 PC7 WGA Drought

Hydro+PS Steam - Boiler Combined Cycle Combustion Turbine

Cogeneration Renewable Other

GWh

Low Hydro Results

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2022 WGA Drought – Changes in Generation by State vs. Low Hydro

Alberta

Arizon

a

British

Colu

mbia

Califo

rnia

Colora

do

Idah

o

Mex

ico

Mon

tana

Nevad

a

New M

exico

Orego

n

South

Dak

ota

Texas

Utah

Was

hingt

on

Wyo

ming

-4,000,000

-3,000,000

-2,000,000

-1,000,000

0

1,000,000

2,000,000

Annual Energy Difference: 2022 PC1-2 Low Hydro Sensitivity vs. 2022 PC7 WGA Drought

Hydro+PS Steam - Boiler Combined Cycle Combustion Turbine

Cogeneration Renewable Other

GWh

Result of increased forced outages applied to plants in the Lower Colorado water basin

Result of increased forced outages applied to plants in the California water basin

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2022 WGA Drought – Changes in Region to Region Transfers

AZNMNV To Ca_S

Basin To AZNMNV

Basin To Ca_N

Basin To Ca_S

Ca_N To Ca_S

Canada To NWUS

NWUS To Basin

NWUS To Ca_N

NWUS To Ca_S

RMPA To AZNMNV

RMPA To Basin

-1000

-500

0

500

1000

1500

2000

2500

3000

3500

Region to Region Transfers - aMW

2022 2022 PC1-2 2022 PC7

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2022 WGA Drought – Changes in Transmission Utilization

P45 SDG&E-CFE

P29 Intermountain-Gonder

P26 Northern-Southern California

P03 Northwest-British Columbia

P47 – Southern New Mexico

Most Heavily Utilized PathsIncreases in U90 Relative to Common >5% Case Indicated in Red

P08 Montana to Northwest

P60 Inyo-Control

P27 IPP DC Line

P11 West of Crossover

P10 West of Colstrip

P01 Alberta-British Columbia

Most Heavily Utilized Paths U75 U90 U99

P45 SDG&E-CFE 43.54% 35.30% 30.87%P08 Montana to Northwest 67.18% 34.59% 16.27%P03 Northwest-British Columbia 52.68% 32.47% 20.78%P29 Intermountain-Gonder 230 kV 46.63% 23.50% 12.59%P47 Southern New Mexico (NM1) 44.46% 22.07% 8.95%P26 Northern-Southern California 29.32% 17.91% 12.21%P01 Alberta-British Columbia 16.60% 13.47% 11.77%P11 West of Crossover 68.11% 5.38% 0.00%P10 West of Colstrip 56.47% 0.00% 0.00%

Questions or thoughts on this study?