NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Capacity Value: Evaluation of WECC Rule of Thumb

WECC Data Working Group

Michael Milligan, Ph.D. Eduardo Ibanez, Ph.D.

Western Electricity Coordinating Council Webinar

June 9, 2015

NREL/PR-5D00-64879

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Objective

• Compare LOLE, wind/solar capacity values with ‘rules of thumb’ used in Western Interconnection Planning

• Provide alternative recommendations to WECC’s TEPPC modeling efforts

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ELCC: Measure Contribution of Generator to Resource Adequacy

0.06

0.07

0.08

0.09

0.1

0.11

0.12

8 8.5 9 9.5 10 10.5 11

Loss

of L

oad

Expe

ctat

ion

(day

s/ye

ar)

Load (GW)

Original Reliability Curve

Target Reliability Level

1

2

4

3

Each generator added to the system helps increase the load that can be supplied at all reliability levels.

Added generators

Gi+1 Gi Gi+2 Gn-2

400MW

Evaluation of WECC Rules of Thumb for Resource Adequacy for Wind and Solar

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5

Numerical Example

• Comparison of metrics and effect on capacity value

• Using WECC’s Transmission Expansion Planning Policy Committee (TEPPC) 2024 o Long-term transmission study for the U.S. Western

Interconnection

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Footprint and pools

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Tool: REPRA

• Renewable Energy Probabilistic Resource Assessment tool (REPRA) o Include variable generation in traditional probabilistic-

based methods o Allow comparison of alternative targets, metrics (LOLE,

ENS, LOLH, etc.) o Answer questions from the IVGTF report

http://www.nerc.com/files/IVGTF1-2.pdf o Available as open-source package for R statistical software

• More information: o Ibanez, Milligan, “Impact of Transmission on Resource

Adequacy in Systems with Wind and Solar Power,” www.nrel.gov/docs/fy12osti/53482.pdf

o –, “Probabilistic Approach to Quantifying the Contribution of Variable Generation and Transmission to System Reliability,” http://www.nrel.gov/docs/fy12osti/56219.pdf

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Definition of pools and reserve margins

Pool Includes Summer Margin

Winter Margin

AZ-NM-NV Arizona, New Mexico, Southern Nevada

13.6% 14.0%

Basin Idaho, Northern Nevada, Utah 13.7% 13.7%

Alberta Alberta 12.6% 13.9% BC British Columbia 12.6% 13.9% CA-North Northern California, San

Francisco, SMUD 15.0% 12.1%

CA-South Southern California Edison, San Diego Gas & Electric, LADWP, Imperial Irrigation District

15.2% 11.0%

NWPP Pacific Northwest, Montana 17.5% 19.2% RMPA Colorado, Wyoming 15% 15.9%

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Contribution to Resource Adequacy

Generation Type AZ-NM-NV Basin Alberta BC CA-North CA-South NWPP RMPA Biomass RPS 100% 100% 100% 100% 66% 65% 100% 100% Geothermal 100% 100% 100% 100% 72% 70% 100% 100% Small Hydro RPS 35% 35% 35% 35% 35% 35% 35% 35% Solar PV 60% 60% 60% 60% 60% 60% 60% 60% Solar CSP0 90% 95% 95% 95% 72% 72% 95% 95% Solar CSP6 95% 95% 95% 95% 100% 100% 95% 95% Wind 10% 10% 10% 10% 16% 16% 5% 10% Hydro 70% 70% 90% 90% 70% 95% 70% 70% Pumped Storage 100% 100% 100% 100% 100% 100% 100% 100% Coal 100% 100% 100% 100% 100% 100% 100% 100% Nuclear 100% 100% 100% 100% 100% 100% 100% 100% Combined Cycle 95% 95% 100% 95% 95% 95% 95% 95% Combustion Turbine 95% 95% 100% 95% 95% 95% 95% 95% Other Steam 100% 100% 100% 100% 100% 100% 100% 100% Other 100% 100% 100% 100% 100% 100% 100% 100% Negative Bus Load 100% 100% 100% 100% 100% 100% 100% 100% Dispatchable DSM 100% 100% 100% 100% 100% 100% 100% 100%

Capacity credit by technology and pool that TEPPC uses to meet the reserve margin criteria

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Contribution to Resource Adequacy

Generation Type AZ-NM-NV Basin Alberta BC CA-North CA-South NWPP RMPA Biomass RPS 100% 100% 100% 100% 66% 65% 100% 100% Geothermal 100% 100% 100% 100% 72% 70% 100% 100% Small Hydro RPS 35% 35% 35% 35% 35% 35% 35% 35% Solar PV 60% 60% 60% 60% 60% 60% 60% 60% Solar CSP0 90% 95% 95% 95% 72% 72% 95% 95% Solar CSP6 95% 95% 95% 95% 100% 100% 95% 95% Wind 10% 10% 10% 10% 16% 16% 5% 10% Hydro 70% 70% 90% 90% 70% 95% 70% 70% Pumped Storage 100% 100% 100% 100% 100% 100% 100% 100% Coal 100% 100% 100% 100% 100% 100% 100% 100% Nuclear 100% 100% 100% 100% 100% 100% 100% 100% Combined Cycle 95% 95% 100% 95% 95% 95% 95% 95% Combustion Turbine 95% 95% 100% 95% 95% 95% 95% 95% Other Steam 100% 100% 100% 100% 100% 100% 100% 100% Other 100% 100% 100% 100% 100% 100% 100% 100% Negative Bus Load 100% 100% 100% 100% 100% 100% 100% 100% Dispatchable DSM 100% 100% 100% 100% 100% 100% 100% 100%

Capacity credit by technology and pool that TEPPC uses to meet the reserve margin criteria

Solar PV = 60% everywhere Wind varies from 5-16%

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Wind capacity value for different metrics

TEPPC assumed 10% capacity value (except 16% In CA and 5% NWPP)

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PV capacity value for different metrics

TEPPC assumed 60% capacity value at all locations

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PV: Comparison of WECC Rules of Thumb and ELCC

0

10

20

30

40

50

60

70

AZ-NM-NV Basin CA-North CA-South RMPA Interconnect

Sola

r PV

Capa

city

Val

ue a

s % o

f Rat

ed C

apac

ity

WECC

LOLE

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Wind: Comparison of WECC Rules of Thumb and ELCC

0

5

10

15

20

25

30

35

AZ-NM-NV Basin CA-North CA-South RMPA Alberta NWPP BC

Win

d Ca

paci

ty V

alue

as %

of R

ated

Cap

acity

WECC

LOLE

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Conclusions – Resource Adequacy Metrics

• Estimating resource adequacy levels in the presence or renewables is an open area of research

• Capacity values are not very sensitive to metric or adequacy level selection

• Calculated CV were smaller than TEPPC assumptions; TEPPC cases might be slightly underbuilt

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WECC may want to consider:

• Adopting these capacity values by type of resource and zone as new rules of thumb o Subject to periodic revision

• Utilizing NREL’s REPRA (open source) model to complement existing modeling resources in TEPPC process

• Utilizing an alternative approach to incorporate capacity valuation into the TEPPC process