20200417Staff 10-38 to Avista.pdf

SECOND PRODUCTION REQUEST
TO AVISTA 1 APRIL 17, 2020
EDWARD JEWELL
DEPUTY ATTORNEY GENERAL
IDAHO PUBLIC UTILITIES COMMISSION
PO BOX 83720
BOISE, IDAHO 83720-0074
[phone]
IDAHO BAR NO. 10446

Street Address for Express Mail:
11331 W CHINDEN BLVD, BLDG 8, SUITE 201-A
BOISE, ID 83714

Attorney for the Commission Staff

BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION

IN THE MATTER OF AVISTA’S 2020
ELECTRIC INTEGRATED RESOURCE PLAN
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CASE NO. AVU-E-19-01

SECOND PRODUCTION
REQUEST OF THE
COMMISSION STAFF TO
AVISTA CORPORATION

The Staff of the Idaho Public Utilities Commission, by and through its attorney of record,
Edward Jewell, Deputy Attorney General, request that Avista Corporation (Company) provide
the following documents and information as soon as possible, or by FRIDAY,
MAY 8, 2020.
This Production Request is continuing, and the Company is requested to provide, by way
of supplementary responses, additional documents that it or any person acting on its behalf may
later obtain that will augment the documents produced.
Please provide answers to each question, supporting workpapers that provide detail or are
the source of information used in calculations. The Company is reminded that responses
pursuant to Commission Rules of Procedure must include the name and phone number of the
person preparing the document, and the name, location and phone number of the record holder
and if different the witness who can sponsor the answer at hearing if need be. Reference IDAPA
31.01.01.228.
RECEIVED
2020 April 17,PM2:16
IDAHO PUBLIC
UTILITIES COMMISSION

SECOND PRODUCTION REQUEST
TO AVISTA 2 APRIL 17, 2020
In addition to the written copies provided as response to the questions, please provide all
Excel and electronic files on CD with formulas activated.

REQUEST NO. 10: Please explain how changing from a 20-year IRP time frame to a
25-year time frame affects the portfolio cost and resource selections.

REQUEST NO. 11: In reference to: “Moving to 25 years led to removing some of the
cost estimates for resources beyond 20 years.” IRP at 2-12. Please provide the cost estimates
that were removed and explain the effect of removing these costs.

REQUEST NO. 12: In reference to: “Avista assigned peak credits to renewable and
storage resources depending on their ability to meet peak loads using its Avista Reliability
Assessment Model (ARAM).” IRP at 2-11. Please explain how the ARAM model assigns peak
credits and how this method is different than past IRPs.

REQUEST NO. 13: Please provide the workpapers used to create Peak Credit table 9.11
in Excel format with formulas enabled.

REQUEST NO. 14: Please describe how ARAM validates resource adequacy and
resource peak contributions.

REQUEST NO. 15: Related to reliability analysis, please respond to the following:
a. Please explain why 2030 was chosen as the year to test reliability.
b. Please explain why the Company did not perform its reliability analysis over
multiple years. Please explain the difficulties, benefits, and costs to perform of
performing this type of analysis over multiple years.
c. Please explain why the Company did not perform its reliability analysis on
multiple or all resource portfolios. Please explain the difficulties, benefits, and
costs to perform this analysis on all or multiple resource portfolios.
d. In Audit Request Response No. 16, the Company stated, “Future IRPs may
contain broader reliability analysis.” Please provide additional detail on the

SECOND PRODUCTION REQUEST
TO AVISTA 3 APRIL 17, 2020
Company’s plan for a broader reliability analysis, which includes details on the
purpose, objectives, and scope for the plan.
e. In Audit Request Response No. 16, the Company stated, “Avista used the same
peak credit and planning margin on all portfolios in the IRP.” Please explain the
risk of some portfolio scenarios over or under building resources and exceeding or
failing reliability tests due to the use of a single planning margin for all portfolios.
Please include an explanation on the effect of the total cost of the portfolios and
all issues with comparing the portfolios to each other.

REQUEST NO. 16: Please explain why the Company believes it is reasonable to
replace use per customer elasticity estimates with “academic assumptions and estimates”. IRP at
3-8.

REQUEST NO. 17: The Use Per Customer Regression Equation (Eq. 3.2) contains no
autoregressive term; however, the accompanying text discusses inclusion of the Autoregressive
Integrated Moving Average (ARIMA) terms in the model. Please provide the revised version of
Equation 3.2 that was actually used to model Usage Per Customer. Please answer the following
questions regarding the model that was actually used to model Usage Per Customer:
a. What is the highest order autoregressive term used in this model?
b. Were the autoregressive predictors lagged values of Usage Per Customer, or were
they lagged values of the prediction error?

REQUEST NO. 18: On page 3-11, the Company states that it made its forecast for
Residential Schedule 1 customer growth using an ARIMA time series model. The Company also
states that, if the growth rates generated from this approach differ from forecasted population
growth, the forecasts are adjusted to match forecasted population growth. Please answer the
following questions:
a. Why is an ARIMA model justified, and what is the meaning of the ARIMA terms
in the model?
b. What is the highest order autoregressive term in the model?

SECOND PRODUCTION REQUEST
TO AVISTA 4 APRIL 17, 2020
c. Given that the Company adjusts the forecast to match the forecast of population
growth, why was population growth not used directly?

REQUEST NO. 19: The Company's Residential Long-Run Forecast Relationship is
expressed in Equation 3.3. Please confirm that ly, cy, and uy are expressed in terms of percentage
growth.

REQUEST NO. 20: In the discussion of Monthly Peak Load Forecast Methodology
(IRP at 3-18 through 3-23), the equation numbers and text references do not appear to match.
a. Please confirm that the textual reference to Equation 3.9 is referring to Equation
3.4.
b. Please confirm that the textual references to Equations 3.10 and 3.11 are referring
to Equations 3.7 and 3.8.
c. Please provide corrections to any other textual references that may be in error.

REQUEST NO. 21: In Peak Load Regression Model Equation 3.4, please explain the
following:
a. The notation ed,g,y for t,y=June 2004↑.
b. Please explain why June 2004 was used as a start date for the data series.

REQUEST NO. 22: On pages 3-18 and 3-19, the Company states that "...a series of
peak forecasts from the current year, yc , are generated out N years by using forecasted levels of
GDP as shown in Equation 3.3." Staff notes that Equation 3.3 includes no term representing a
forecasted level of GDP. Please explain how GDP forecasts were incorporated into Equation
3.3.

REQUEST NO. 23: The text on page 3-21 states that Table 3.5 shows estimated peak
load growth rates with and without the two large industrial customers; however, Table 3.5
includes only forecasts including large industrial customers. Please provide the forecast without
the two large industrial customers.

SECOND PRODUCTION REQUEST
TO AVISTA 5 APRIL 17, 2020
REQUEST NO. 24: Table 1-2 of the Company's 2016-2017 Idaho Electric Energy
Efficiency report states that Gross Verified Savings were 42,223,004 kWh, or approximately
4.82 aMW. Please provide workpapers, with electronic links intact, showing how the Company
obtained the 155 aMW savings value shown on page 5-1 of the Company's 2019 IRP.

REQUEST NO. 25: Please provide the analysis and workpapers that Avista used to
determine estimated savings for feeder upgrades in 2020 as 269 MWh, and 152 MWh in 2021.
IRP at 5-5.

REQUEST NO. 26: Please describe how Avista determined that Energy Efficiency will
meet 71% of future load growth. If Demand Response is a factor in the estimate, please break
out the contributions from Energy Efficiency and Demand Response potential separately.

REQUEST NO. 27: As part of an aggressive plan to meet future load growth, please
describe the Company plan for Demand Response Rates. IRP at 6-4.

REQUEST NO. 28: Regarding Liquid Air Storage, the Company states on pages 9-14
that round-trip efficiencies can be improved using the waste heat from existing natural gas-fired
turbines. Given the clean energy goals enumerated by the Company on page 1-6, what thermal
resources will be available to boost energy efficiency? Please provide an estimate of the heat
that will be available when Liquid Air Storage systems are producing electricity.

REQUEST NO. 29: On pages 9-24 and 9-25, the Company describes analyses that it
conducted in order to determine the intermittent generation costs of wind and solar resources.
These costs include a $5 per MWH for wind, $1.80 for solar, and a 10% capacity value adder
determined by Avista's ELCC studies. Please provide the studies, including a description of
study methodology, that were used to determine these values.

REQUEST NO. 30: Please explain why the Company did not test multiple closure dates
for Colstrip besides both units closing in 2025, both units closing in 2035, and unit #3 closing in
2025 while unit #4 closing in 2035.

SECOND PRODUCTION REQUEST
TO AVISTA 6 APRIL 17, 2020
REQUEST NO. 31: With the current coal supply agreement set to expire Dec. 31, 2025,
is Colstrip fuel expense after 2025 modeled in any portfolio? Please explain why or why not.

REQUEST NO. 32: Please explain how Avista will calculate the additional cost
associated with assigning a new capacity deficiency date, in part driven by the Company’s
decision to eliminate Colstrip capacity to meet Washington legislative initiatives and Avista’s
clean energy goals.

REQUEST NO. 33: Please provide the capacity shortfall and related costs associated
with an early Colstrip retirement in 2025. Please include an analysis of financial impacts to
Idaho customers. Audit Request Response Nos. 4 and 5.

REQUEST NO. 34: Is Avista considering the sale of Colstrip ownership shares in
exchange for Power Purchase Agreement(s) for renewable energy? Please explain Audit
Request Response No. 6

REQUEST NO. 35: Please provide an economic analysis that demonstrates when it is
no longer economically beneficial to operate Colstrip. Please allow the retirement date to float
based on the economics of the resource as opposed to adjusting retirement dates to 2025 or 2035
and provide all workpapers with formulas enabled.

REQUEST NO. 36: In reference to the state-specific study mentioned on page 12-5 in
the IRP, please provide the workpapers (with formulas enabled) used to calculate the increase in
Idaho rates.

REQUEST NO. 37: Please explain why portfolios scenarios without CETA (Scenarios
#2 and #7) show new resource additions prior to the 2026 deficit year identified in the IRP.

REQUEST NO. 38: Please describe how the Company will define, separate, and track
Idaho and Washington financial obligations for Colstrip and CETA costs. Audit Request
Response No. 4.

SECOND PRODUCTION REQUEST
TO AVISTA 7 APRIL 17, 2020
Dated at Boise, Idaho, this 17th day of April 2020.

_______________________________________
Edward Jewell
Deputy Attorney General

i:umisc:prodreq/avue19.1ejme prod req2
CERTIFICATE OF SERVICE
CERTIFICATE OF SERVICE

I HEREBY CERTIFY THAT I HAVE THIS 17th DAY OF APRIL 2020,
SERVED THE FOREGOING SECOND PRODUCTION REQUEST OF THE
COMMISSION STAFF TO AVISTA CORPORATION, IN CASE NO. AVU-E-19-01,
BY E-MAILING A COPY THEREOF, TO THE FOLLOWING:

LINDA GERVAIS
MGR REGULATORY POLICY
AVISTA CORPORATION
PO BOX 3727
SPOKANE WA 99220-3727
E-MAIL: [e-mail]
[e-mail]

DAVID J MEYER
VP & CHIEF COUNSEL
AVISTA CORPORATION
PO BOX 3727
SPOKANE WA 99220-3727
E-MAIL: [e-mail]

/s/ Reyna Quintero __
SECRETARY