20240813PAC to Staff 82_ 87_ 89_ 90_ 92_ 99_ 105 Set 6.pdf

RECEIVED
Tuesday, August 13, 2024
IDAHO PUBLIC
UTILITIES COMMISSION
_ ROCKY MOUNTAIN
POWER
A DIVISION OF PACIFICORP
1407 W North Temple, Suite 330
Salt Lake City, Utah 84116
August 13, 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 6 (82-118)
Please find enclosed Rocky Mountain Power's Responses to IPUC 61h Set Data Requests 82, 87,
89, 90, 92, 99, and 105. These remaining response will be provided under separate cover. Also
provided are non-confidential Attachments. Provided via BOX are Confidential Attachments
and Confidential Response IPUC 117. 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 [phone].
Sincerely,
/s/
Mark Alder
Manager, Regulation
Enclosures
C.c.: Eric L. Olsen/IIPA elokechohawk.com(C)
Lance Kaufman/IIPA lance@ae ism h�(C)
Matthew Nykiel/ICL matthew.n, k�(&gmail.com
Brad Heusinkveld/ICL bheusinkveldkidahoconservation.org
Thomas J. Budge/Bayer tj racineolson.com(C)
Brian C. Collins/Bayer bcollinskconsultbai.com
Greg Meyer/Bayer gmeyer(&consultbai.com
Kevin Higgins/Bayer khia gins kenergystrat.com(C)
Neal Townsend/Bayer ntownsend(&energystrat.com (C)

Ronald L. Williams/PIIC rwilliams&hawleytroxell.com
Brandon Helgeson/PIIC bhel eg son ci,hawleytroxell.com
Bradley Mullins/PIIC brmullins(&mwanalytics.com
Val Steiner/PIIC val.steinergitafos.com
Kyle Williams/PIIC williamskkbvui.edu

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 82
IPUC Data Request 82
Please provide a detailed description of the Company's weather/temperature
normalization method used to normalize revenues, system peak, energy loads, net
power costs, and any other items normalized by this method. In the description,
please identify any changes in the method from Case No. PAC-E-21-07. Please
provide any workpapers supporting the weather/temperature normalization
method, in electronic format with links intact and formulae enabled, for each item
that is normalized including weather spline models and calculations of the
weather adjustment.
Response to IPUC Data Request 82
The Company interprets the term"Normalization"to refer to the process used to
remove the impact of the difference between actual weather and normal weather
from historical energy loads. The Company does not weather normalize peaks.
The normalization process calculates the forecasted energy using actual weather
conditions and subtracts them from calculated load using normal weather
conditions for each weather sensitive class (Residential, Commercial and
Irrigation). The difference is applied to the actual load to create expected actual
load under normal conditions.
Please refer to Attachment IPUC 82-1 which provides the calculation of the 20-
year normal weather heating degree day (HDD) and cooling degree day(CDD)
for the historical weather normalization.
Please refer to Confidential Attachment IPUC 82-2 which provides the weather
spline models used for the historical weather normalization.
Please refer to Attachment IPUC 82-3 which provides the calculation of the class
level weather adjustment.
Please refer to Attachment IPUC 82-4 which provides the allocation of the class
level weather adjustments to rate schedules used to weather normalize the
historical sales.
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.
Recordholder: Lee Elder
Sponsor: Lee Elder

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 87
IPUC Data Request 87
Eller's Direct Testimony states that"the Company will retain RECs for retirement
based on a percentage of participating customers' aggregated load data in the
calendar year immediately preceding the Program Year and based on Idaho-
allocated Company RECs...Participation in this Program will also require
customers to forego revenue credits in their rates from sales of Company entitled
RECs from the RRA."Please explain whether RECs to be retired can exceed
Idaho-allocated RECs.
Response to IPUC Data Request 87
No. The number of renewable energy credits (REC)to be retired for the REC
Option Program will not exceed the number of RECs allocated to Idaho.
Recordholder: Craig Eller
Sponsor: Craig Eller

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 89
IPUC Data Request 89
Pages 12 and 13 of Eller's Direct Testimony states that the number of RECs to be
retired for the REC Option Program is based on the aggregated load for
participating customers multiplied by a percentage of renewable resource
generation from PacifiCorp's system, and the initial percentage of 20%. Please
respond to the following:
(a) Please explain and illustrate through examples that non-participating
customers will receive the amount of REC revenue credits that they currently
receive.
(b) Please explain and illustrate generally whether the Company will financially
benefit from the program. In your answer, please explain if the Company can
benefit by determining which RECs for each resource type will be retired as
described in proposed Schedule No. 74.
(c) Please explain why 20%is a reasonable starting percentage.
(d) Please explain whether the number of retired RECs determined under this
method generally aligns with the value of the foregone revenue credits that the
participating customers would have received from the sales of the RECs.
Please provide evidence to support your answer.
Response to IPUC Data Request 89
(a) The proposed renewable energy credit(REC) Option Program is designed so
that the Company can still market RECs on behalf of non-participating
customers. The following example provides a highly simplified illustration:
Assumptions:
1. Idaho has only 10 customers, each with an annual usage of 1,000
megawatt-hours (MWh).
2. Idaho's annual allocated share of RECs generated is 2,000 RECs.
3. The Company is able to sell 300 RECs for $5 per REC ($/REC).
Scenario 1 —No Program:
In calendar year 2026, the Company markets 2,000 RECs on behalf of non-
participating customers and sells 300 RECs for$5 for a total revenue of
$1,500. This revenue is credited to Idaho customers through the proposed
REC Revenue Adjustment(RRA). For calendar year 2026, the REC
retirements would be:

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 89
Total #RECs allocated to Idaho 2,000
Total Sold to Third Parties (300)
Idaho RECs remaining 1,700
Scenario 2 —Proposed REC Option Program:
Two Idaho customers enroll in the new REC Option Program by October 1,
2025. On January 1, 2026, the Company sets aside 400 RECs for the REC
Option Program (1,000 MWh usage x two customers x 20 percent). The
Company markets the remaining 1,600 RECs on behalf of non-participating
customers and sells 300 RECs for $5/REC for a total revenue of$1,500. This
revenue is credited to non-participating Idaho customers through the proposed
RRA. For calendar year 2026, the REC retirements would be:
Total#RECs allocated to Idaho 2,000
Retired# for REC Option Program (400)
Total Sold to Third Parties (300)
Idaho RECs remaining 1,300
Scenario 3 —Proposed REC Option Program:
Nine Idaho customers enroll in the new Program by October 1, 2025. On
January 1, 2026, the Company sets aside 1,800 RECs for the REC Option
Program (1,000 MWh usage x nine customers x 20 percent). The Company
markets the remaining 200 RECs on behalf of the one remaining non-
participating customer and sells 200 RECs for$5/MWh for a total revenue of
$1,000. This revenue is credited to the one non-participating Idaho customer
through the proposed RRA. For calendar year 2026, the REC retirements
would be:
Total#RECs allocated to Idaho 2,000
Retired# for REC Option Program (1,800)
Total Sold to Third Parties (200)
Idaho RECs remaining 0
Scenario 4 —Proposed REC Option Program:
All 10 Idaho customers enroll in the new REC Option Program by October 1,
2025. On January 1, 2026, the Company sets aside 2,000 RECs for the REC
Option Program(1,000 MWh usage x 10 customers x 20 percent).
Total# RECs allocated to Idaho 2,000
Retired# for REC Option Program (2,000)
Idaho RECs remaining 0

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 89
(b) The Company will not benefit financially from the REC Option Program
participation, including by determining which RECs will be retired. Any
unretired Idaho allocated RECs will continue to be available for sale to third
parties and all associated revenue will be credited to non-participating
customers.
(c) The Company chose 20 percent as it is reasonably approximate to the current
percentage of renewable energy in the Company's supply portfolio.
(d) Yes it does. As stated in the Company's response to subpart(c) above, the 20
percent target was chosen to reasonably approximate the current portion of
customers' loads served by renewable energy. By retiring a similar number of
RECs based on historic usage, participating customers receive similar value to
the foregone revenue credits they would otherwise receive.
Recordholder: Craig Eller
Sponsor: Craig Eller

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 90
IPUC Data Request 90
Page 9 of Eller's Direct Testimony states that"Company witness McCoy
describes how the REC revenue forgone by participating customers would remain
in the existing balancing account and be credited to Idaho's non-participating
customers through the RRA." Please respond to the following:
(a) Please provide justification for the statement in the quote.
(b) Please explain where the forgone revenue comes from if the RECs are retired.
Response to IPUC Data Request 90
(a) Customers participating in the proposed renewable energy credit (REC)
Option Program will not be eligible to receive the REC Revenue Adjustment
(RRA) credit, which will pass back the benefits of REC sales to non-
participating customers. Only the customers who are not participating in the
REC Option Program will receive the RRA credit.
(b) The RECs that are retired on behalf of customers who participate in the REC
Option Program do not generate any revenue. Rather participation in this
program is intended to provide an option for customers to achieve their
corporate sustainability or environmental goals. The phrase "...REC revenue
forgone by participating customers..." is intended to indicate that
participating customers forgo receiving the RRA credit and instead the RRA
credit will only be passed on to non-participating customers.
Recordholder: Craig Eller
Sponsor: Craig Eller

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 92
IPUC Data Request 92
Please respond to the following regarding Day-Ahead/Real-Time (DA/RT)
Adjustments discussed in Mitchell's Direct Testimony:
(a) Please explain how the Official Forward Price Curve (OFPC) is determined.
(b) Please explain why OFPC is used in calculating NPC, instead of the market
prices determined by the Aurora model run.
(c) Please explain and provide work papers illustrating how the OFPC forecast is
scaled to hourly buckets.
(d) Please explain how the percentage-of-market-price adders are determined
based on historical data from 2020 to 2023 and provide an example to
illustrate the calculation. In the explanation, please explain how hourly scaled
average market-indexed prices and hourly scaled average Company purchase
prices are determined.
Response to IPUC Data Request 92
(a) The first 36 months of PacifiCorp's official forward price curve (OFPC) is
based on broker quote averages. The Company receives information from
multiple brokers, each of whom cover multiple delivery points in the power
and/or gas markets. Averages of the most granular(e.g. monthly versus
quarterly) quotes available are used in order to construct the OFPC directly
from third-party information received by the Company. Prices for delivery
periods more than 48 months into the future are based on a third-party long-
term price forecast, and prices for months 37 through 48 are based on a blend
of market quotes and the long-term price forecast. Note: the prices used to
forecast net power costs (NPC) in this general rate case (GRC)proceeding are
based entirely on broker quotes.
(b) The OFPC, as it pertains to NPC, consists entirely of real market prices
(broker quotes). Real market prices are more representative of actual
transaction execution (post day-ahead/real-time (DA/RT) modification) than
modeled market prices.
(c) Monthly prices are shaped into hourly prices using hourly scalars and monthly
scalars. There are three sets of 24-hour hourly scalars per month for
PacifiCorp West (PACW) and PacifiCorp East(PACE). The three scalars are
Monday through Friday, Saturday, and Sunday/North American Electric
Reliability Corporation (NERC) holidays. The hourly scalars are calculated
using the most recent 24 months of California Independent System Operator
(CAISO) day-ahead hourly prices for Malin for PACW and Palo Verde (PV)

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 92
for PACE. The scalars are calculated as the average price of the hour in the
24-month dataset divided by the average price of the hours for the heavy load
hour (HLH) or light load hour(LLH)time period in the 24-month dataset.
The most recent five years of proprietary IntercontinentalExchange (ICE) data
for PV, California-Oregon Border(COB), Mid-Columbia(Mid-C) and Four
Corners (4C) markets, and CAISO data for NP15 and SP15 are used to
calculate PacifiCorp's monthly scalars for the OFPC.
PacifiCorp's hourly and monthly scalars files responsive to this request are
considered highly confidential and commercially sensitive. The Company
requests special handling. Please contact Mark Alder at(801) 220-2313 to
make arrangements for review. Referencing Highly Confidential Attachment
IPUC 92, the Company provides a description of the highly confidential files
as follows:
Highly confidential file "CTIRateServer HIGHLY CONF.xlsm" and highly
confidential file "CTIRateServer HIGHLY CONF.xlam" (the latter is in
Microsoft Excel add-in file format) provide the macros that combine the
resulting hourly and monthly scalars as Microsoft Excel add-in functions for
the March 2024 OFPC. Highly confidential file "Historical Hourly Price
Scalars_2024 03 01 HIGHLY CONF.xlsm"provides the hourly scalars
calculations and highly confidential file "MonthlyScalars_2024Q 1 HIGHLY
CONF.xlsm"provides the monthly scalars calculations, which relate the three
(M-F/Sat/Sun) 12x24 hourly scalar sets within each month. Note: the provided
highly confidential files contain third-party proprietary data (ICE day-ahead
index data).
(d) Please refer to the confidential work papers supporting the direct testimony of
Company witness, Ramon J. Mitchell, specifically confidential file "Aurora
GN Market Prices CONF", tab "Adders Source", rows 250-261 for the
calculation of the flat dollar adders/subtractors (modifiers). The flat dollar
modifier is calculated by comparing the buy and sell prices of the Company's
transactions on 48-month rolling basis against the average day-ahead settled
prices on the ICE differentiated by trading hub, month and time period
(HLH/LLH). This difference in prices is volume weighted to get a flat dollar
modifier differentiated by trading hub, month and time period.
The percentage modifier is calculated off the flat modifier noted in the
Company's response to subpart (a) above as the ratio of flat modifier and the
48-month average of the historical ICE market prices (in dollars per
megawatt-hour($/MWh)), differentiated by trading hub, month and time
period. For example, the percentile modifier for California-Oregon Border
(COB) trading hub HLH purchase for the month of January is calculated as
the ratio of the flat modifier at COB for January HLH purchase and the 48-

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 92
month historical market prices at COB. The formulas in the section noted
above illustrates the example noted here.
The Company scales market-indexed based prices based on the CAISO hourly
scalars. The Company uses the OFPC as described in the Company's response
to subpart(a) above and disaggregates them into hourly prices using the
scalars as described in the Company's response to subpart(c) above. The
scaling of Company prices for its NPC forecasting is based on those hourly
scaled prices coupled with the percentile modifier as noted above.
Recordholder: Elaine Biggs/Doug Staples /Eshwar Vyakarna Rajshekar Rao
Sponsor: John Fritz/Ramon Mitchell

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 99
IPUC Data Request 99
Please respond to the following regarding file "Table NPC Dollar and Table NPC
MWh CONF 2023 Normalized Load.xlsx":
(a) Please define "Special Sales for Resale", "Mid-Columbia Contracts", "Storage
&Exchange", "System Balancing Purchases", "Net Interchange", "U. of F.
Expense", and"Other Generation Expense" on Tab "Source".
(b) Please explain the difference between "Long Term Firm Sales", "Short Term
Firm Sales", and "System Balancing Sales".
(c) Please explain the difference between "Long Term Firm Purchases", "Short
Term Firm Purchases", and "System Balancing Purchases".
(d) Please explain why "Other Generation Expense" on Tab "Source" is not
reflected on Tab "Table(s)NPC Dollar and MWh".
Response to IPUC Data Request 99
(a) "Special Sales for Resale" is the Combination of"Total Long-Term Firm
Sales", "Total Short-Term firm Sales" and "Total System Balancing Sales" as
defined in subpart(b)below.
"Mid-Columbia Contracts" are the costs relating to the hydro facilities
located on the Columbia River, for which the Company has obtained
ownership shares for.
"Total Purchased Power&Net Interchange" is the combination of"Total
Long-Term Firm Purchases), "Total Storage and Exchange", Total-Short
Term Firm Purchases" and "Total System Balancing Purchases".
"Total Wheeling &U. of F. Expense" are the costs incurred by the Company
to use non-Company transmission to serve energy obligations.
"Other Generation Expense" is the cost of generating energy associated with
the Company's Blundell geothermal resources.
(b) Long-term firm (LTF) sales refers to sales contracts executed by the
Company that are greater than one year in contract length. Short-term firm
(STF) sales refers to sales contracts executed by the Company that are less
than one year in contract length. System balancing sales refers to modeled
output sales in the Aurora model that are analogous to transactions executed
by the Company in the spot market(day-ahead and real-time transactions).

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 99
(c) Long-term firm(LTF)purchases refers to purchase contracts executed by the
Company that are greater than one year in contract length. Short-term firm
(STF) purchases refers to the purchase contracts executed by the Company
that are less than one year in contract length. System balancing purchases
refer to modeled output purchases in the Aurora model that are analogous to
transactions executed by the Company in the spot market(day-ahead and
real-time transactions).
(d) During the preparation of this data request response, the Company identified
an error in"Other Generation Expense" on tab "Source"not being reflected
on tab "Table(s)NPC Dollar and MWY. Please refer to Confidential
Attachment IPUC 99 for the corrected version of"Table(s)NPC Dollar and
MWh".
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.
Recordholder: Eshwar Vyakarna Raj shekar Rao
Sponsor: Ramon Mitchell

PAC-E-24-04/Rocky Mountain Power
August 13, 2024
IPUC Data Request 105
IPUC Data Request 105
Please explain if the method and resulting loads used to determine the
temperature-normalization revenue adjustment discussed on Page 41 of McCoy
Exhibit No. 48 are the same loads used as the "Normal" loads prior to adding the
extreme weather adjustment used for NPC.
Response to IPUC Data Request 105
The Company interprets the reference to "extreme weather adjustment" to mean
"weather adjustment". Based on the foregoing interpretation, the Company
responds as follows:
Company witness, Shelley McCoy's, temperature-normalization revenue
adjustment is based on the 2023 historical test year weather adjustment and is
consistent with the normalization of energy sales, revenue and billing
determinants as conducted by Company witness, Robert M. Meredith. Please refer
to the Company's response to IPUC Data Request 83.
Net power costs (NPC)uses this same weather normalization applied to actual
hourly loads in its 2023 weather normalized loads.
Recordholder: Lee Elder
Sponsor: Lee Elder