20220209Quarterly Report.pdf

JULIA A. HILTON
Deputy General Counsel
[e-mail]
February 9, 2022
Ms. Jan Noriyuki
Secretary
Idaho Public Utilities Commission
PO Box 83720
Boise, ID 83720-0074
Re: Case No. IPC-E-16-19
Deferral and Recovery of Costs Associated with Participation in Energy Imbalance
Market – California Independent System Operator (“CAISO”) Quarterly Energy
Imbalance Market (“EIM”) Benefits Assessment Report
Dear Ms. Noriyuki:
Pursuant to Order No. 33706 issued in Case No. IPC-E-16-19, Idaho Power Company
(“Idaho Power” or “Company”) hereby submits the quarterly CAISO Western EIM Benefits Report
(“Report”) for the fourth quarter of 2021. The Report presents CAISO’s quantification of benefits
associated with participation in the Western EIM. For the fourth quarter of 2021, CAISO estimated
Western EIM gross benefits of $7.09 million for Idaho Power.
The EIM has provided financial benefits to the Company, and ultimately its customers.
However, as discussed in Idaho Power’s prior quarterly compliance filings as well as the
Company’s May 24, 2019, Report of EIM Benefits and Costs of Participation, CAISO’s calculation
of benefits for Idaho Power is overstated due to several of the modeling assumptions used in its
benefit calculation. The Company developed a more precise methodology, that uses inputs
specific to Idaho Power, for determining actual EIM benefits, the details of which are discussed in
the Company’s May 24, 2019, Report of EIM Benefits and Costs of Participation.
If you have any questions regarding this report, please contact Matt Larkin, Revenue
Requirement Senior Manager, at [phone] or [e-mail].
Sincerely,
Julia A. Hilton
Enclosure
RECEIVED
2022 FEB 09 PM 4:04
IDAHO PUBLIC
UTILITIES COMMISSION

www.westernEIM.com

WESTERN EIM BENEFITS REPORT
Fourth Quarter 2021

Prepared by: Market Analysis and Forecasting

January 31, 2022
WESTERN EIM BENEFITS REPORT FOURTH QUARTER 2021

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CONTENTS

EXECUTIVE SUMMARY ........................................................................................................... 3
BACKGROUND ......................................................................................................................... 4
WESTERN EIM ECONOMIC BENEFITS IN Q4 2021 ................................................................ 4
CUMULATIVE ECONOMIC BENEFITS SINCE INCEPTION ................................................................... 5
INTER-REGIONAL TRANSFERS ............................................................................................................. 6
WHEEL THROUGH TRANSFERS .......................................................................................................... 16
REDUCED RENEWABLE CURTAILMENT AND GHG REDUCTIONS ....................................21
FLEXIBLE RAMPING PROCUREMENT DIVERSITY SAVINGS ..............................................23
CONCLUSION ..........................................................................................................................27
APPENDIX 1: GLOSSARY OF ABBREVIATIONS...................................................................28
WESTERN EIM BENEFITS REPORT FOURTH QUARTER 2021

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EXECUTIVE SUMMARY
This report presents the benefits associated with
participation in the Western Energy Imbalance
Market (EIM).
The measured benefits of participation in the
Western EIM include cost savings, increased
integration of renewable energy, and improved
operational efficiencies including the reduction of
the need for real-time flexible reserves.
This analysis demonstrates the benefit of
economic dispatch in the real time market across a larger
EIM footprint with more diverse resources and geography.

Q4 2021 Gross Benefits by Participant
(millions $)
Arizona Public Service $9.95
BANC $31.44
California ISO $55.50
Idaho Power $7.09
LADWP $10.60
NorthWestern Energy $5.87
NV Energy $9.38
PacifiCorp $39.81
PNM $3.44
Portland General Electric $7.41
Powerex -$0.02
Puget Sound Energy $5.42
Salt River Project $11.99
Seattle City Light $4.65
TID $1.61
Total $204.14

*EIM Quarterly Benefit Report Methodology:
https://www.westerneim.com/Documents/EIM-BenefitMethodology.pdf.
Gross benefits from EIM since November 2014
$1.93 billion
ECONOMICAL
$204.14 M
Gross benefits realized due to more
efficient inter-and intra-regional
dispatch in the Fifteen-Minute
Market (FMM) and Real-Time
Dispatch (RTD)*

ENVIRONMENTAL
16,283
Metric tons of CO2** avoided
curtailments

OPERATIONAL
53%
Average reduction in flexibility
reserves across the footprint
2021
Q4 BENEFITS
WESTERN EIM BENEFITS REPORT FOURTH QUARTER 2021

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**The GHG emission reduction reported is associated with the avoided curtailment only. The current market process and
counterfactual methodology cannot differentiate the GHG emissions resulting from serving ISO load via the EIM versus dispatch that
would have occurred external to the ISO without the EIM. For more details, see
http://www.caiso.com/Documents/GreenhouseGasEmissionsTrackingReport-FrequentlyAskedQuestions.pdf
BACKGROUND
The Western EIM began financially binding operation on November 1, 2014 by optimizing
resources across the ISO and PacifiCorp Balancing Authority Areas (BAAs). NV Energy began
participating in December 2015, Arizona Public Service and Puget Sound Energy began
participating in October 2016, and Portland General Electric began participating in October
2017. Idaho Power and Powerex began participating in April 2018, and the Balancing Authority
of Northern California (BANC) began participating in April 2019. Seattle City Light and Salt River
Project began participating in April 2020.
Most recently, new balancing authorities began participating in the Western EIM, with the
Turlock Irrigation District (TID) in March 2021, the second phase of BANC in March 2021, and
the Los Angeles Department of Water and Power (LADWP) and Public Service Company of
New Mexico (PNM) in April 2021, followed by NorthWestern Energy (NWMT) starting in June
2021.
The Western EIM footprint now includes portions of Arizona, California, Idaho, Montana,
Nevada, New Mexico, Oregon, Utah, Washington, Wyoming, and extends to the border with
Canada.
WESTERN EIM ECONOMIC BENEFITS IN Q4 2021
Table 1 shows the estimated EIM gross benefits by each region per month1. The monthly
savings presented show $87.62 million for October, $54.74 million for November, and $61.78
million for December with a total estimated benefit of $204.14 million for this quarter23. This level
of EIM benefits accrued from having additional EIM areas participating in the market and
economical transfers displacing more expensive generation. The benefits accrued in 2021
totaled $738.9 million.

1 The EIM benefits reported here are calculated based on available data. Intervals without complete data are
excluded in the calculation. The intervals excluded due to unavailable data are normally within a few percent
points of the total intervals.
2 For several quarterly estimates, CAISO benefits have been calculated on a variation of the counterfactual
methodology. For CAISO only the logic has considered offline resources as part of the bid stack in the
counterfactual. In Q4 2021, CAISO has identified some questionable results that drove persistent negative
benefits for CAISO when considering offline resources. Consequently this logic has been not used for Q4
CAISO benefits in the meantime CAISO further asses this logic component. With this approach the
counterfactual calculation for CAISO follows the same methodology applicable to all EIM entities.
3 There were negative EIM benefits for Powerex due to small price variations from congestion effects between
the EIM cost and the counterfactual costs. The EIM market fully accounts and prices for the effects of energy,
congestion and losses while the counterfactual is an estimate based only on energy prices.
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Region October November December Total
APS $3.71 $3.11 $3.13 $9.95
BANC $9.95 $11.79 $9.70 $31.44
CISO $37.43 $5.00 $13.07 $55.50
IPCO $2.28 $2.76 $2.05 $7.09
LADWP $4.68 $2.90 $3.02 $10.60
NVE $2.87 $3.37 $3.14 $9.38
NWMT $1.79 $2.22 $1.86 $5.87
PAC $13.53 $13.15 $13.13 $39.81
PGE $2.56 $2.13 $2.72 $7.41
PNM $0.49 $1.68 $1.27 $3.44
PSE $1.58 $1.71 $2.13 $5.42
PWRX -$0.09 -$0.13 $0.20 -$0.02
SCL $1.38 $1.59 $1.68 $4.65
SRP $4.86 $2.98 $4.15 $11.99
TID $0.60 $0.48 $0.53 $1.61
Total $87.62 $54.74 $61.78 $204.14
TABLE 1: Q4 2021 benefits in millions USD
CUMULATIVE ECONOMIC BENEFITS SINCE INCEPTION
Since the start of the EIM in November 2014, the cumulative economic benefits of the market
have totaled $1.93 billion. The quarterly benefits have grown over time as a result of the
participation of new BAAs, which results in benefits for both the individual BAA but also
compounds the benefits to adjacent BAAs through additional transfers. The ISO began
publishing quarterly EIM benefit reports in April 2015.4
Graph 1 illustrates the gross economic benefits of the EIM by quarter for each participating
BAA.

4 Prior reports are available at https://www.westerneim.com/Pages/About/QuarterlyBenefits.aspx
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GRAPH 1: Cumulative economic benefits for each quarter by BAA
INTER-REGIONAL TRANSFERS
A significant contributor to EIM benefits is transfers across balancing areas, providing access to
lower cost supply, while factoring in the cost of compliance with greenhouse gas (GHG)
emissions regulations when energy is transferred into the ISO. As such, the transfer volumes
are a good indicator of a portion of the benefits attributed to the EIM. Transfers can take place in
both the 15-Minute Market and Real-Time Dispatch (RTD).
Generally, transfer limits are based on transmission and interchange rights that participating
balancing authority areas make available to the EIM, with the exception of the PacifiCorp West
(PACW) -ISO transfer limit and the Portland General Electric (PGE) -ISO transfer limit in RTD.
These RTD transfer capacities between PACW/PGE and the ISO are determined based on the
allocated dynamic transfer capability driven by system operating conditions. This report does
not quantify a BAA’s opportunity cost that the utility considered when using its transfer rights for
the EIM.
Table 2 provides the 15-minute and 5-minute EIM transfer volumes with base schedule
transfers excluded. The EIM entities submit inter-BAA transfers in their base schedules. The
benefits quantified in this report are only attributable to the transfers that occurred through the
EIM. The benefits do not include any transfers attributed to transfers submitted in the base
schedules that are scheduled prior to the start of the EIM.
The transfer from BAA_x to BAA_y and the transfer from BAA_y to BAA_x are separately
reported. For example, if there is a 100 Megawatt-Hour (MWh) transfer during a 5-minute
interval, in addition to a base transfer from ISO to NVE, it will be reported as 100 MWh
from_BAA ISO to_BAA NEVP, and 0 MWh from_BAA NEVP to_BAA ISO in the opposite
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direction. The 15-minute transfer volume is the result of optimization in the 15-minute market
using all bids and base schedules submitted into the EIM. The 5-minute transfer volume is the
result of optimization using all bids and base schedules submitted into EIM, based on unit
commitments determined in the 15-minute market optimization. The maximum transfer
capacities between EIM entities are shown in Graph 2 below.

Month

From BAA

To BAA
15min EIM transfer
(15m – base)
5min EIM transfer
(5m – base)
AZPS CISO 126,718 95,247
October AZPS LADWP 23,564 23,724
AZPS NEVP 5,178 6,691
AZPS PACE 5,448 6,430
AZPS PNM 29,136 33,129
AZPS SRP 47,541 48,839
BANC CISO 19,948 14,544
BANC TIDC 113 200
CISO AZPS 9,057 11,044
CISO BANC 63,826 78,042
CISO LADWP 57,014 75,039
CISO NEVP 9,693 14,486
CISO PACW 0 3,125
CISO PGE 1,915 5,895
CISO PWRX 73,389 16,712
CISO SRP 53,548 67,826
CISO TIDC 30,677 31,673
IPCO NEVP 52,571 32,273
IPCO NWMT 0 1
IPCO PACE 7,187 4,584
IPCO PACW 68,875 79,249
IPCO PSEI 3,959 4,000
IPCO SCL 6,511 5,968
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LADWP AZPS 1,560 1,770
LADWP CISO 133,723 103,311
LADWP NEVP 9,125 11,045
LADWP PACE 36,789 42,820
NEVP AZPS 1,979 1,628
NEVP CISO 152,236 108,835
NEVP IPCO 21,807 25,021
NEVP LADWP 45,032 46,058
NEVP PACE 925 1,612
NWMT IPCO 24,406 23,294
NWMT PACE 4,199 3,500
NWMT PACW 0 5
NWMT PGE 18 55
NWMT PSEI 25 42
PACE AZPS 144,903 143,801
PACE IPCO 83,161 97,022
PACE LADWP 91,731 81,717
PACE NEVP 153,423 140,279
PACE NWMT 2,447 885
October PACE PACW 17,211 23,342
PACE SRP 0 0
PACW CISO 16,227 35,010
PACW IPCO 33,564 18,648
PACW NWMT 0 5
PACW PGE 64,254 71,792
PACW PSEI 27,835 21,528
PACW SCL 870 622
PGE CISO 22,073 628
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PGE NWMT 39 49
PGE PACW 19,823 23,770
PGE PSEI 0 0
PGE SCL 863 680
PNM AZPS 22,668 20,019
PNM SRP 0 0
PSEI IPCO 0 0
PSEI NWMT 12 42
PSEI PACW 0 0
PSEI PGE 0 0
PSEI PWRX 19,936 20,714
PSEI SCL 17,936 20,106
PWRX CISO 0 571
PWRX PSEI 6,681 7,794
SCL IPCO 7,440 8,950
SCL PACW 1,458 1,891
SCL PGE 1,997 2,371
SCL PSEI 8,950 10,177
SRP AZPS 18,992 17,278
SRP CISO 115,398 106,186
SRP PACE 0 0
SRP PNM 1,931 3,171
TIDC BANC 24 153
TIDC CISO 14,808 13,117
November AZPS CISO 104,205 75,933
AZPS LADWP 11,246 12,165
AZPS NEVP 3,498 3,142
AZPS PACE 6,248 5,610
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AZPS PNM 31,753 30,710
AZPS SRP 23,178 22,748
BANC CISO 2,220 1,650
BANC TIDC 20 88
CISO AZPS 17,693 21,769
CISO BANC 114,241 138,041
CISO LADWP 25,232 35,924
CISO NEVP 17,405 14,661
CISO PACW 2,980 14,664
CISO PGE 11,986 6,649
CISO PWRX 98,295 21,741
CISO SRP 30,491 40,835
CISO TIDC 18,992 21,176
IPCO NEVP 41,632 27,786
IPCO NWMT 2,166 1,651
IPCO PACE 7,240 5,327
IPCO PACW 42,402 47,884
IPCO PSEI 0 0
IPCO SCL 6,056 6,908
LADWP AZPS 4,208 5,613
LADWP CISO 135,486 100,422
LADWP NEVP 5,930 5,983
LADWP PACE 17,286 21,691
November NEVP AZPS 6,507 7,031
NEVP CISO 148,978 101,253
NEVP IPCO 36,622 36,686
NEVP LADWP 19,841 24,145
NEVP PACE 1,117 1,296
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NWMT IPCO 16,653 20,962
NWMT PACE 5,976 2,991
NWMT PACW 62 77
NWMT PGE 9 86
NWMT PSEI 56 81
PACE AZPS 102,288 100,270
PACE IPCO 93,119 116,384
PACE LADWP 108,195 99,891
PACE NEVP 128,747 116,462
PACE NWMT 12,050 15,109
PACE PACW 24,858 36,049
PACE SRP 0 0
PACW CISO 54,142 42,294
November PACW IPCO 36,762 25,026
PACW NWMT 0 4
PACW PGE 65,825 74,364
PACW PSEI 28,713 28,753
PACW SCL 969 933
PGE CISO 37,222 565
PGE NWMT 519 118
PGE PACW 17,942 20,014
PGE PSEI 2,810 3,398
PGE SCL 966 967
PNM AZPS 29,247 29,338
PNM SRP 0 0
PSEI IPCO 0 0
PSEI NWMT 16 25
PSEI PACW 27,184 33,199
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PSEI PGE 7,586 8,679
PSEI PWRX 22,889 22,224
PSEI SCL 16,265 17,510
PWRX CISO 0 442
PWRX PSEI 5,372 7,101
SCL IPCO 8,769 7,642
SCL PACW 956 1,185
SCL PGE 2,112 2,354
SCL PSEI 25,917 26,330
SRP AZPS 29,530 28,095
SRP CISO 84,284 72,394
SRP PACE 0 0
SRP PNM 1,857 2,649
TIDC BANC 2,286 1,985
TIDC CISO 9,732 5,567
December AZPS CISO 85,385 58,979
AZPS LADWP 9,874 11,809
AZPS NEVP 8,074 12,620
AZPS PACE 6,239 10,617
AZPS PNM 53,480 47,956
AZPS SRP 15,330 17,701
BANC CISO 12,456 6,719
BANC TIDC 51 488
CISO AZPS 27,797 35,313
CISO BANC 89,230 112,811
CISO LADWP 30,622 43,740
CISO NEVP 26,410 31,965
CISO PACW 10,863 29,855
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CISO PGE 6,603 11,285
CISO PWRX 21,054 10,071
CISO SRP 36,605 48,050
CISO TIDC 9,674 11,570
IPCO NEVP 34,783 21,240
IPCO NWMT 921 1,212
IPCO PACE 3,172 2,663
IPCO PACW 46,462 44,975
IPCO PSEI 0 0
IPCO SCL 4,248 4,588
LADWP AZPS 7,730 6,581
LADWP CISO 92,737 56,678
LADWP NEVP 6,211 8,254
LADWP PACE 17,132 27,634
NEVP AZPS 14,664 13,940
NEVP CISO 137,125 79,328
NEVP IPCO 46,632 53,305
NEVP LADWP 23,009 34,544
NEVP PACE 3,406 3,670
NWMT IPCO 20,427 20,816
NWMT PACE 8,820 5,482
NWMT PACW 46 24
NWMT PGE 45 56
NWMT PSEI 8 43
December PACE AZPS 58,186 52,146
PACE IPCO 89,195 99,725
PACE LADWP 91,985 74,351
PACE NEVP 165,210 141,369
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PACE NWMT 10,412 14,236
PACE PACW 27,028 39,355
PACE SRP 0 0
PACW CISO 58,589 34,744
PACW IPCO 26,405 20,960
PACW NWMT 2 252
December PACW PGE 42,828 48,863
PACW PSEI 18,166 17,755
PACW SCL 716 600
PGE CISO 32,808 688
PGE NWMT 27 284
PGE PACW 39,354 37,772
PGE PSEI 0 0
PGE SCL 1,010 862
PNM AZPS 22,283 21,475
PNM SRP 0 0
PSEI IPCO 0 0
PSEI NWMT 15 68
PSEI PACW 47,668 49,857
PSEI PGE 0 0
PSEI PWRX 11,057 11,876
PSEI SCL 16,547 17,112
PWRX CISO 0 479
PWRX PSEI 16,366 16,174
SCL IPCO 11,799 11,041
SCL PACW 1,377 1,582
SCL PGE 1,717 1,993
SCL PSEI 14,182 15,476
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TABLE 2: Energy transfers (MWh) in the FMM and RTD markets for Q4 2021

GRAPH 2: Estimated maximum transfer capacity (EIM entities operating in Q4 2021)
SRP AZPS 32,980 34,603
SRP CISO 106,135 96,060
SRP PACE 0 0
SRP PNM 3,553 5,184
TIDC BANC 79 150
TIDC CISO 14,395 11,401
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WHEEL THROUGH TRANSFERS
As the footprint of the Western EIM grows, wheel-through transfers may become more common.
In order to derive the wheel-through transfers for each EIM BAA, the ISO uses the following
calculation for every real-time interval dispatch:

 Total import: summation of transfers above base transfers coming into the EIM BAA
under analysis
 Total export: summation of all transfers above base transfers going out of the EIM
BAA under analysis
 Net import: the maximum of zero or the difference between total imports and total
exports
 Net export: the maximum of zero or the difference between total exports and total
imports
 Wheel through: the minimum of the EIM transfers into (total import) or EIM transfer
out (total export) of a BAA for a given interval

All wheel-through transfers are summed over both the month and the quarter.

Currently, an EIM entity facilitating a wheel through receives no direct financial benefit for
facilitating the wheel; only the sink and source directly benefit. As part of the Western EIM
Consolidated Initiatives stakeholder process, the ISO committed to monitoring the wheel
through volumes to assess whether, after the addition of new EIM entities, there is a potential
future need to pursue a market solution to address the equitable sharing of wheeling benefits.

The ISO will continue to track the volume of wheel-through transfers in the EIM market in the
quarterly reports.

This volume reflects the total wheel-through transfers for each EIM BAA, regardless of the
potential paths used to wheel through. The net imports and exports estimated in this section
reflect the overall volume of net imports and exports; in contrast, the imports and exports
provided in Table 2 reflect the gross transfers between two EIM BAAs.

The metric is measured as energy in MWh for each month and the corresponding calendar
quarter, as shown in Tables 3 through 6 and Graphs 3 through 6.

BAA Net Export Net Import Wheel Through
AZPS 176,908 204,314 348,075
BANC 23,010 330,987 703
CISO 628,521 897,656 326,830
IPCO 81,067 377,181 209,501
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LADWP 137,939 309,628 254,405
NEVP 158,684 209,032 380,011
NWMT 73,879 30,252 3,740
PACE 1,263,130 18,339 131,309
PACW 154,857 196,962 291,736
PGE 78,381 223,041 11,705
PNM 70,534 122,714 341
PSEI 126,317 83,156 75,604
PWRX 25,999 97,117 6,591
SCL 67,429 53,283 23,707
SRP 361,538 241,690 4,628
TIDC 31,895 64,738 513

TABLE 3: Estimated wheel-through transfers in Q4 2021

GRAPH 3: Estimated wheel-through transfers in Q4 2021

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BAA Net Export Net Import Wheel-Through
AZPS 76,885 58,116 137,748
BANC 14,564 78,087 196
CISO 205,362 379,327 98,986
IPCO 39,911 87,120 86,210
LADWP 59,334 126,986 99,971
NEVP 51,791 73,373 131,593
NWMT 26,316 342 642
PACE 430,340 2,157 57,547
PACW 66,898 50,001 81,656
PGE 23,076 77,940 2,255
PNM 19,956 36,381 65
PSEI 25,992 28,569 14,997
PWRX 5,953 35,242 2,424
SCL 12,358 16,393 11,070
SRP 125,755 115,849 1,120
TIDC 13,114 31,722 167
TABLE 4: Estimated wheel-through transfers in October 2021

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GRAPH 4: Estimated wheel-through transfers in October 2021

BAA Net Export Net Import Wheel- Through
AZPS 33,749 75,597 116,779
BANC 1,636 140,204 101
CISO 192,248 277,032 123,743
IPCO 20,119 137,645 69,644
LADWP 46,870 85,485 86,978
NEVP 55,859 53,896 114,634
NWMT 22,363 15,065 1,864
PACE 451,227 5,318 33,865
PACW 63,652 42,986 110,422
PGE 18,684 85,829 6,412
PNM 29,298 33,403 43
PSEI 46,541 30,395 35,321
PWRX 5,454 41,955 2,106
SCL 32,139 20,944 5,412
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SRP 101,854 62,200 1,396
TIDC 7,377 21,117 175
TABLE 5: Estimated wheel-through transfers in November 2021

GRAPH 5: Estimated wheel-through transfers in November 2021

BAA Net Export Net Import Wheel Through
AZPS 66,275 70,601 93,547
BANC 6,810 112,696 406
CISO 230,910 241,296 104,101
IPCO 21,037 152,416 53,647
LADWP 31,735 97,157 67,456
NEVP 51,034 81,764 133,784
NWMT 25,199 14,845 1,234
PACE 381,563 10,864 39,898
PACW 24,307 103,974 99,658
PGE 36,620 59,272 3,039
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PNM 21,280 52,930 232
PSEI 53,784 24,192 25,286
PWRX 14,592 19,919 2,061
SCL 22,932 15,946 7,225
SRP 133,929 63,640 2,112
TIDC 11,404 11,899 172
TABLE 6: Estimated wheel-through transfers in December 2021

GRAPH 6: Estimated wheel-through transfers in December 2021
REDUCED RENEWABLE CURTAILMENT AND GHG REDUCTIONS
The Western EIM benefit calculation includes the economic benefits that can be attributed to
avoided renewable curtailment within the ISO footprint. If not for energy transfers facilitated by
the EIM, some renewable generation located within the ISO would have been curtailed via
either economic or exceptional dispatch. The total avoided renewable curtailment volume in
MWh for Q4 2021 was calculated to be 12,075 MWh (October) + 12,817 MWh (November) +
13,152 MWh (December) = 38,044 MWh total.
There are environmental benefits of avoided renewable curtailment as well. Under the
assumption that avoided renewable curtailments displace production from other resources at a
default emission rate of 0.428 metric tons CO2/MWh, avoided curtailments displaced an
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estimated 16,283 metric tons of CO2 for Q4 2021. Avoided renewable curtailments also may
have contributed to an increased volume of renewable credits that would otherwise have been
unavailable. This report does not quantify the additional value in dollars associated with this
benefit. Total estimated reductions in the curtailment of renewable energy in the ISO footprint,
along with the associated reductions in CO2, are shown in Table 7.
Year Quarter MWh Eq. Tons CO2
1 8,860 3,792
2015 2 3,629 1,553
3 828 354
4 17,765 7,521
1 112,948 48,342
2016 2 158,806 67,969
3 33,094 14,164
4 23,390 10,011
1 52,651 22,535
2017 2 67,055 28,700
3 23,331 9,986
4 18,060 7,730
1 65,860 28,188
2018 2 129,128 55,267
3 19,032 8,146
4 23,425 10,026
1 52,254 22,365
2019 2 132,937 56,897
3 33,843 14,485
4 35,254 15,089
1 86,740 37,125
2020 2 147,514 63,136
3 37,548 16,071
4 39,956 17,101
2021 1 76,147 32,591
2 109,059 46,677
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3 23,042 9,862
4 38,044 16,283
Total 1,570,200 671,966

TABLE 7: Total reduction in curtailment of renewable energy and associated reductions in CO2
FLEXIBLE RAMPING PROCUREMENT DIVERSITY SAVINGS
The Western EIM facilitates procurement of flexible ramping capacity in the FMM to address
variability that may occur in the RTD. Because variability across different BAAs may happen in
opposite directions, the flexible ramping requirement for the entire EIM footprint can be less
than the sum of individual BAA’s requirements. This difference is known as flexible ramping
procurement diversity savings.
Starting in 2016, the ISO replaced the flexible ramping constraint with flexible ramping products
that provide both upward and downward ramping. The minimum and maximum flexible ramping
requirements for each BAA and for each direction are listed in Table 8.
Month BAA Direction Minimum
requirement
Maximum
requirement
AZPS up 0 345
October BANC up 0 89
CISO up 0 2,669
IPCO up 0 183
LADWP up 0 230
NEVP up 0 360
NWMT up 0 141
PACE up 0 568
PACW up 0 182
PGE up 0 237
PNM up 0 171
PSEI up 0 160
PWRX up 0 251
SCL up 0 36
SRP up 0 210
TIDC up 0 14
ALL EIM up 0 2,917
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AZPS down 0 404
BANC down 0 86
CISO down 0 1,122
IPCO down 0 200
LADWP down 0 269
NEVP down 0 469
NWMT down 0 173
PACE down 0 591
PACW down 0 181
PGE down 0 215
PNM down 0 200
October PSEI down 0 200
PWRX down 0 300
SCL down 0 35
SRP down 0 382
TIDC down 0 15
ALL EIM down 0 1,413
AZPS up 29 345
November BANC up 7 89
CISO up 337 2,669
IPCO up 36 192
LADWP up 30 230
NEVP up 27 360
NWMT up 26 156
PACE up 98 612
PACW up 36 182
PGE up 35 237
PNM up 44 171
PSEI up 35 192
PWRX up 71 286
SCL up 4 37
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SRP up 31 210
TIDC up 2 12
ALL EIM up 462 2,917
AZPS down 32 403
BANC down 4 92
CISO down 186 1,122

November
IPCO down 44 178
LADWP down 29 238
NEVP down 18 350
NWMT down 36 149
PACE down 111 582
PACW down 51 180
PGE down 46 215
PNM down 36 194
PSEI down 51 200
PWRX down 75 300
SCL down 1 35
SRP down 16 382
TIDC down 1 15
ALL EIM down 269 1,413

December

AZPS up 24 276
BANC up 8 82
CISO up 307 2,445
IPCO up 32 192
LADWP up 27 230
NEVP up 21 326
NWMT up 26 156
PACE up 83 612
PACW up 57 182
PGE up 32 214
PNM up 34 171
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December

PSEI up 36 192
PWRX up 78 286
SCL up 4 37
SRP up 23 128
TIDC up 2 14
ALL EIM up 409 2,917
AZPS down 27 300
BANC down 4 92
CISO down 193 1,122
IPCO down 48 190
LADWP down 26 262
NEVP down 11 347
NWMT down 37 149
PACE down 103 459
PACW down 60 181
PGE down 36 210
PNM down 43 161
PSEI down 35 200
PWRX down 71 300
SCL down 5 35
SRP down 22 154
TIDC down 1 15
ALL EIM down 259 1,413
Table 8: Flexible ramping requirements
The flexible ramping procurement diversity savings for all the intervals averaged over the month
are shown in Table 9. The percentage savings is the average MW savings divided by the sum of
the individual BAA requirements.

October November December
Direction Up Down Up Down Up Down
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Average MW saving 1,258 1,322 1,214 1,304 1,175 1,224
Sum of BAA requirements 2,597 2,195 2,546 2,249 2,462 2,162
Percentage savings 48% 60% 48% 58% 48% 57%
Table 9: Flexible ramping procurement diversity savings in Q4 2021
Flexible ramping capacity may be used in RTD to handle uncertainties in the future interval. The
RTD flexible ramping capacity is prorated to each BAA. Flexible ramping surplus MW is defined
as the awarded flexible ramping capacity in RTD minus its share, and the flexible ramping
surplus cost is defined as the flexible ramping surplus MW multiplied by the flexible ramping
EIM-wide marginal price. A positive flexible ramping surplus MW is the capacity that a BAA
provided to help other BAAs, and a negative flexible ramping surplus MW is the capacity that a
BAA received from other BAAs.
The EIM dispatch cost for a BAA with positive flexible ramping surplus MW is increased
because some capacities are used to help other BAAs. The flexible ramping surplus cost is
subtracted from the BAA’s EIM dispatch cost to reflect the true dispatch cost of a BAA. Please
see the Benefit Report Methodology for more details.

CONCLUSION
Using state-of-the-art technology to find and deliver low-cost energy to meet real-time demand,
the Western EIM demonstrates that utilities can realize financial and operational benefits
through increased coordination and optimization. In addition to these benefits, the Western EIM
provides significant environmental benefits through the reduction of renewable curtailments
during periods of oversupply.
Sharing resources across a larger geographic area reduces greenhouse gas emissions by using
renewable generation that otherwise would have been turned off. The quantified environmental
benefits from avoided curtailments of renewable generation from 2015 to-date reached 671,966
metric tons of CO2, roughly the equivalent of avoiding the emissions from 141,278 passenger
cars driven for one year.

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APPENDIX 1: GLOSSARY OF ABBREVIATIONS

Abbreviation Description
APS Arizona Public Service
BAA Balancing Authority Area
BANC Balancing Authority of Northern California
CISO, ISO California ISO
EIM Energy Imbalance Market
FMM Fifteen Minute Market
GHG Greenhouse Gas
IPCO Idaho Power
MW Megawatt
MWh Megawatt-Hour
NVE NV Energy
PAC PacifiCorp
PACE PacifiCorp East
PACW PacifiCorp West
PGE Portland General Electric
PSE Puget Sound Energy
PWRX Powerex
RTD Real Time Dispatch
SCL Seattle City Light
SRP Salt River Project
TID Turlock Irrigation District