OVERVIEW

Thank you for the opportunity to comment. The PacifiCorp Team, including Brett, Rikin, Kris, Scott and Jamie appreciate NorthernGrid’s due diligence as well as for incorporating much of the initial comments submitted in Iteration 1. However, after reviewing the Pre-Final Report , we find it necessary to submit the enclosed relevant comments, referenced as Iteration 2 comments . We look forward to receiving a response and potential resolution from NorthernGrid.

Grammar/Format/Technical Edits

PacifiCorp Comments covering

NorthernGrid Economic Study Request – Seminoe Pump Storage Project

Submitted: 06/02/2023 – Iteration 2

Attachment K “Economic Study” Principals

12.1.1 Regional

NorthernGrid, in coordination with Enrolled Parties and the

Enrolled Parties Planning Committee, is to perform in accordance

with this Part E of this Attachment K economic studies pursuant

to requests submitted by stakeholders in accordance with Section

12.2.1 of this Attachment K related to conditions within the

Enrolled Party Region.

12.2.1 Regional

A stakeholder, which includes Enrolled Parties, may request that

NorthernGrid initiate a study to examine scenarios where potential transmission solutions or investments could result in:

net reduction in total production cost to supply system load,

reduced congestion; or

the integration of new resources and/or loads on an aggregate or regional basis (a “Regional Economic Study”).

The following comments constitute the collective input from the PacifiCorp Team. The response is noted as follows:

1--Excerpts of the report are shown in quotes

2—Bolded font (orignally in the report) indicate the general area of questions/concerns raised by PacifiCorp

3—Red font provides a more comprehensive statement of the issue and the technical response

Stated under Analysis, page 3, line 7-9 - - “The analysis herein does not address the reliability or the assumed operations of this pumped storage project; it is a representation of study results bounded by the assumptions and the program limitations.”

Actually, the results are bounded by the assumptions used and not by the software.  The software does what you tell it to do.

Remove “and the program limitations”

Explained under Results, page 4, line 9-14:

“Using the “Daily Scheduling on Price” option, GridView models pumped storage in the following fashion: first, GridView dispatches the system without the pumped storage project. GridView then determines how the pumped storage projects should operate based on the system conditions/state of the pumped storage devices/availability of the pumped storage to pump or charge and then re-dispatches the system, including the pumped storage projects. GridView staff were consulted throughout the modeling process to ensure the SPS was modeled correctly given the “Daily Scheduling on Price” option.”

Replace bolded description above with the following:

Using the Multi-Integer-Optimization (MIO) and the “Daily Scheduling based on Price” option, the GridView Pumped Hydro Storage (PHS) algorithm commits PHS in consideration of other system resources based on PHS pumping efficiency/plant volume/ramping rates to optimize and schedule the generation/pumping dispatch 24-hour forward.  This option does not require iterating to determine a pre-price forecast.

GridView allows the user to schedule PHS with the given storage target looking at weekly, daily or monthly schedules with consideration of load pattern, wind and solar patterns (these are fixed energy patterns). It supports modeling for high wind events for the chosen period by emptying storage or to prepare for rain days (or low solar generation for the period) by filling up storage over weekly or even longer period of time.

The 2032 ADS has negative pricing for wind and solar (- $25), reflecting either an investment tax credit (ITC) or a production tax credit (PTC).  Significant addition of utility-scale solar and BTM PV has changed the net load shape; in some areas, the net daily minimum load now occurs mid-day.  Accordingly, Hydro generation is responding to the price signals, and had shifted its operation from “Peak” to “Load – Solar – Wind”.

The daily ending storage targets from longer duration storage scheduling will guide how to best utilize storage plants in the daily optimization. The charge and discharge prices optimize over 24 hours with given initial storage and ending storage targets.  

“Under Results, page 5, line5-6 … “Figure 2 shows the maximum hourly output for each of the individual 300 MW units. The units range from -300 MW (pumping mode) to +300 MW (generating mode). The ramp rate of the SPS units allow for very quick transitions between pumping and generating. The range indicates that the point of interconnection allows for congestion-free output and charging of the pumped storage units.

Reaching full capacity does not indicate that the point of interconnection allows for congestion-free output, nor does it address the reliability of serving the added 900 MW SPS.

Further, the bolded statement (last sentence) is presumptuous and should be removed.

Page 7, line 9: “The regional impact of the installation of 900 MW at the 500 kV Aeolus substation can be observed through measuring the impact to select Western Electric Coordinating Council (WECC) Paths.”

The analyses stopped short of determining where the SPS energy was actually dispatched; obviously, it is not evident from the measurement on limited paths (path 14, 17, 20 and 36).  The 2032 ADS case has in it, Energy Gateway South, Energy Gateway West and B2H— the bulk system responsible for not adding congestion on these traditionally monitored paths. 

Further, the analyses did not address the following claims from the Requestor:

The project would significantly enhance capacity of Gateway transmission to deliver additional high quality wind energy from WY to UT or to PNW

Provide shaping and firming of WY wind to meet capacity needs

provide shaping and firming of UT solar via the Clover/Mona area to meet capacity needs

Under Conclusion, page 28:

“The results of this analysis suggest that the regional impact of the addition of 900 MW of pumped storage at the 500 kV Aeolus bus on the NorthernGrid system with more than 50,000 MW of load may be minimal, given the assumptions of the study and the modeled operation of the SPS project. The SPS project did not significantly increase or reduce congestion on the future Gateway system. The SPS project did not significantly impact the Wyoming wind output or Utah solar. System inertia is not 9 addressed in a production cost modeling output.”

The Conclusion is looking much better than what was stated in the first iteration.  However, still missing from PacifiCorp’s iteration-1 comments: “The result of this study did not fully quantify the benefits that the requester proposed as are listed in the “Request” section of the report.”

Graphics

No response submitted.

General

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Open-user defined

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Open-user defined

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