20241016PAC to Staff 181 2nd Supplemental(Redacted).pdf

RECEIVED
Wednesday, October 16,2024
IDAHO PUBLIC
_ ROCKY MOUNTAIN UTILITIES COMMISSION
POWER
A DIVISION OF PACIFICORP
1407 W North Temple, Suite 330
Salt Lake City, Utah 84116
October 16, 2024
Monica Barrios-Sanchez
Commission Secretary
Idaho Public Utilities Commission
11331 W. Chinden Blvd.
Bldg. 8, Ste. 201-A
Boise, ID 83714
monica.barrio ssanchez(apuc.Idaho.gov
S ecretarygpuc.idaho.gov
RE: ID PAC-E-24-04
IPUC Set 10 (175-204)
Please find enclosed Rocky Mountain Power's 2nd Supplemental Response to IPUC 10t' Set Data
Request 181. Provided via BOX is Confidential Response IPUC 181 2nd Supplemental.
Confidential information is provided subject to protection under IDAPA 31.01.01.067 and
31.01.01.233, the Idaho Public Utilities Commission's Rules of Procedure No. 67 —Information
Exempt from Public Review, and further subject to the non-disclosure agreement(NDA)
executed in this proceeding.
If you have any questions, please feel free to call me at(801) 220-2313.
Sincerely,
/s/
Mark Alder
Manager, Regulation
Enclosures
C.c.: Eric L. Olsen/IIPA elo(&echohawk.com(C)
Lance Kaufman/IIPA lancekae.isg insi hg t.com(C)
Matthew Nykiel/ICL matthew.nykiel&amail.com
Brad Heusinkveld/ICL bheusinkveld(a�idahoconservation.org
Thomas J. Budge/Bayer ti(&racineolson.com(C)
Brian C. Collins/Bayer bcollins(&consultbai.com
Greg Meyer/Bayer gmeyerkconsultbai.com
Kevin Higgins/Bayer khig gins kenergystrat.com(C)
Neal Townsend/Bayer ntownsendkenergystrat.com (C)
Ronald L. Williams/PIIC rwilliams(&hawleytroxell.com

Brandon Helgeson/PIIC bhelgeson(&hawleytroxell.com
Bradley Mullins/PIIC brmullinskmwanalytics.com
Val Steiner/PIIC val.steiner(a-)itafos.com
Kyle Williams/PIIC williamsknasbyui.edu

PAC-E-24-04/Rocky Mountain Power
October 16, 2024
IPUC Data Request 181 —2nd Supplemental
IPUC Data Request 181
Please respond to the following regarding Tab "Emerg Purch+Trapp Sales" of
Excel File "ID GRC 2025 2023 Normalized Load.xlsm".
(a) Please define "Emergency Purchases".
(b) Please explain how the MWh amounts of Emergency Purchases from Line
171 to Line 218 are determined.
(c) Please explain how the costs of Emergency Purchases from Line 61 to Line
108 are determined.
(d) Please explain the cost impact of Emergency Purchases on Net Power Costs.
(e) If the cost impact is zero, please explain why it is zero. Also, if the cost
impact is zero, please confirm that the net expenses on Line 112 are not
included in the proposed Net Power Cost.
(f) Please explain what Column "Discount/Premium" represents.
(g) Please explain how "Discount/Premium" is used in the calculation of the costs
of Emergency Purchases.
1" Supplemental request received on September 2, 2024 from Idaho Public
Utilities Commission (IPUC) staff: Please explain why Emergency Purchases
are valued at 125% of market prices, instead of 100% of market prices. Also,
please explain why they are not valued at their dispatch costs.
CONFIDENTIAL REQUEST - 2nd Supplemental request received on
October 9 2024 from IPUC staff: Please reconcile Idaho's load of
megawatt-
hours (MWh) on tab "1 Hourl Load 2023" of"2023 Normalized Load.xlsx with
Idaho's load of
on tab "Load"of"ID_GRC_2025_2023 Normalized
Load.xlsm".
2nd Supplemental Response to IPUC Data Request 181
Further to the Company's prior responses to IPUC Data Request 181 and to the
supplemental request received from Idaho Public Utilities Commission (IPUC)
staff on October 9, 2024, the Company provides the following additional
information:

PAC-E-24-04/Rocky Mountain Power
October 16, 2024
IPUC Data Request 181 —2nd Supplemental
The Company has determined that it is to be expected that total time period
summations of the load provided in the confidential work papers supporting the
direct testimony of Company witness, Ramon J. Mitchell, specifically confidential
file "2023 Normalized Load" and confidential file "ID_GRC_2025 2023
Normalized Load.xlsm"would not match due to the nature of aligning days of the
week in 2023 with days of the week in 2025.
Example, January 5 in 2023 is a Thursday whereas January 5 in 2025 is a Sunday.
Thursdays are days with both heavy load hours (HLH) and light load hours
(LLH), whereas Sundays are days with only LLH. Therefore, the days in 2023
have to be shifted to match the days in 2025 to ensure that the days of the week
are aligned appropriately. Example, under one methodology, January 8, 2023 (a
Sunday) could be mapped to January 5, 2025 (a Sunday).
When shifting days, the megawatt-hour (MWh) totals will not match after the
shifting since in this example methodology, 2023 days have to be shifted by three
days backwards. This would leave December 29, 2025 through December 31,
2025 needing to be covered by January 1, 2023 through January 3, 2023.
However, December 29, 2025 is a Monday, and January 1, 2023 is a Sunday.
Therefore, a day would have to be repeated in 2023 and a day would have to be
discarded in 2023 to match 2025. January 4, 2023 can match to both January 1,
2025 and December 31, 2025 while January 1, 2023 would be discarded using
this methodology.
Aurora, has a native methodology, "DOW", to account for this realignment of
days. The DOW logic (copied from the Aurora help file) is provided below:
"Day of Week- To automatically align a particular year of data to the days of
week in another year, add IDOW to the end of the time series hourly reference
that includes a year and Aurora will do extra work to match up the days of week
in the simulation year with the original year, e.g.
hr WindShapelERCOTWestl20l8lDOW. It does this using the following method:
• For a given simulation date, Aurora finds the current day of week for it, and
for the corresponding date in the reference year.
• If the day of week is the same for both, then that reference date is used.
• Otherwise, Aurora adds some number of days (less than seven) to the
reference date to get to a date that has the same day of week as the simulation
date. If that date is still in the reference year, it is used.
• Otherwise, in the case where the simulation date is at the end of December
and the found reference date is in January of the next year, Aurora subtracts
364 days from the reference date and uses that day.

PAC-E-24-04/Rocky Mountain Power
October 16, 2024
IPUC Data Request 181 —2nd Supplemental
For example, suppose that the reference year is 2018 and the current simulation
date is 7/5/2022, a Tuesday. The date chosen from the reference year would be
7/10/2018, a corresponding Tuesday. If using the same years, and the simulation
date was 12/30/2022, a Friday, then the date chosen from the reference year
would be 1/5/2018, the nearest corresponding Friday".
Recordholder: Isaiah Zacharia/Eshwar Vyakarna Raj shekar Rao
Sponsor: Ramon Mitchell