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D. Change to a Zonal Approach with this Alternate Plan
The System Restoration Plan underlying the Alternate Plan presented in this Reply will take a zonal approach, and will have a greater number of regional islands, or zones than we have today. Figure 3-1 below summarizes the change from our current approach.
Figure 3-1: Summary of Change in System Restoration Plan Approach
While a different approach, the concepts remain the same – alignment of the zones is intended to match customer loads with the new types and locations of generation resulting from this Resource Plan to repower and stabilize the grid.
As shown Figure 3-2 below, we expect to have nine zones throughout our NSP System footprint. If the Alternate Plan is approved, we will transition to the zonal approach over time, likely over the next ten years.
Figure 3-2: Anticipated System Restoration Plan Zones
Blackstart capabilities continue to be a fundamental element of the System Restoration Plan. Today, we rely on a single Blackstart Unit in Minnesota and Wisconsin to set the plan in motion.13 With the zonal approach, we will need Blackstart capabilities in each of the new zones. However, as outlined in Table 3-2 below, while the Alternate Plan includes more firm dispatchable Units, the overall level of thermal resources – and carbon emissions – on the NSP System will be substantially lower than it would be with the current System Restoration Plan
reflected in our 2020 Supplement. Another exciting change with the zonal approach is that it is more diversified, in that it will not rely on one or two large generators to repower a large portion of the system. Rather, small generators will be geographically distributed around our service area that will create a series of smaller islands that we will eventually join together, which will allow for the incorporation of renewables as part of the start-up process. And while this plan will ensure at least the same
restoration pace, it also has the potential to restore greater numbers of customers across our entire footprint (not just our load centers) faster than the current plan.
13 In some parts of our service area where we are not the largest generator, we rely on other utilities to start the restoration.
When assessing our restoration plans, we begin with our forecasts for peak load, since it is a good representation of cold-load “pick-up.” When loads have been offline for long periods of time, we expect a large spike in load from household motors (e.g., air conditioners, refrigerators, freezers, etc.) that start-up once an area is re-energized.
This cold-load pick-up mimics a system peak and eventually settles out as homes adjust temperatures – but we have to plan to the peak. We show the peak load projections that we used for our restoration estimates below
Table 3-2: Forecasted 2030 Loading for Summer and Winter
Region 2030 Summer 2030 Winter
NSP Overall 9,042 MW 6,881 MW
MN 6,465 MW 4,920 MW
WI 1,899 MW 1,455 MW
SD 362 MW 275 MW
ND 319 MW 240 MW
The anticipated 2030 summer peak load of approximately 9,050 MW breaks down to roughly 3,450 MW residential and 5,600 MW non-residential load. Looking ahead to 2030, it appears that there will be sufficient firm dispatchable generation to restore all residential load, from a complete regional perspective. The next block of load, namely commercial and industrial loads will be dependent on any remaining firm, available renewables and available resources from outside the NSP System. We note that we use residential load as a benchmark in system restoration planning due to the
implications on human life from an extended outage – particularly in weather extremes, as was illustrated in Texas with Winter Storm Uri. However, we develop our plan cognizant of the need to restore critical loads such as hospitals and water services as quickly as possible.
Table 3-3 below illustrates the difference between the resources involved with our current centralized plan and the new zonal plan. Specifically, we show the resources included in the modeling for our Alternate Plan and in relation to the resources associated with our current centralized restoration plan.
This table helps to illustrate the increased resilience of our new zonal approach. For example, by 2030 we will significantly increase our ability to incorporate renewable resources – going from utilization of approximately 50 MW of solar resources located near the Twin Cities today to nearly 6,000 MW of renewables located across our footprint in the Alternate Plan. We note that, in this table, the 2021 Centralized EP
Plan column includes all resources (including PPAs) that we currently have as part of our restoration plan, and the 2030 Modified Zonal Plan column includes all resources we expect to be in-service as of 2030 and available for system restoration based on our proposed zonal approach.
When we look at what renewable generation is available for restoration purposes, we take into consideration the generators’ proximity to the islands and whether or not it is interconnected on the NSP System transmission or another entity’s transmission.
With the focus on load centers in our current centralized approach, there are very few renewable resources in proximity to the island that we are building out from the Twin Cities metro area – minimizing the role of renewables, which are generally in rural areas distant from the load centers. Because the zonal approach will build small, geographically-dispersed islands, we are in a better position to incorporate our renewable resources to restore customers – and it increases our potential to restore greater numbers of customers across our entire footprint faster than our current
restoration because of the smaller, geographically-dispersed islands approach. We will also improve our ability to restore all or nearly all of our system from our own
resources, rather than relying neighboring utilities.
Table 3-3: Comparison of Centralized Plan and Modified Zonal Restoration Plan
NSP 2021 Centralized EP
Plan 2030 Modified Zonal Plan with Alternate Plan Firm Dispatchable (FD)
Generation Available 6,595 MW 5,175 MW
Restoration % by XE only FD
generation (Summer) 45-70% 55%
Restoration % by XE only FD
generation (Winter) 80-90% 75%
XE-owned Renewables Available
for Utilization 1,691 MW 5,930 MW
XE-owned Renewables
Utilization Rate 50 MW 2,025 MW
Total XE owned Resources for
restoration 6,645 MW 7,200 MW
Total % Restored (Summer) 45-70% 80%
Total % Restored (Winter) 80-90% 105%
Resource Gap without
Renewables 2,445 MW 3,865 MW
Resource Gap after using
Renewables 2,395 MW 1,840 MW
*Includes additional blackstart resources beyond those included in economic modeling.
#This value takes into consideration location of the renewables within the zonal plan and utilizes the anticipate availability multiplier used by MISO for accreditation, which is 18% for wind and 50% for solar and storage. This reduces the amount of renewables that we have available for restoration purposes as shown in the table (XE-owned Renewables Utilization Rate.
Table 3-4 below shows our restoration estimates under the Alternate Plan with limited additional resources needed for restoration in addition to what is selected in our
economic modeling. From a very high level, it appears that these levels of system resources are adequate to restore most residential loads and a substantial amount of commercial and industrial loads during both Summer and Winter load conditions.
Table 3-4: Generation MW Gap Analysis per Zone (MW) – Alternate Plan with
Generation Total Usable With Without
MN-1 5,305 2,015 2,030 1,810 Solar 905 -2,370 -3,275 100%
*Additional blackstart resources will be required to complete the transition to the zonal plan from the centralized restoration plan currently in use in order to restore residential load.
+Assumes no Sherco CC was constructed and Sherco 3 has retired. No firm dispatchable generation within this Zone in 2030.
Additional firm dispatchable resources will be identified in the future.
Although the zonal restoration plan will largely be adequate to restore most residential and commercial and industrial loads during both Summer and Winter load conditions, there remains a gap between available planned resources and projected loads. With renewables, the gap during summertime conditions appears to be approximately 1,840 MW if renewables can be used at the accredited levels we have projected for this purpose. However, as discussed in the Reliability section, the variable nature of
renewables introduces a higher level of uncertainty as to whether they will be available when needed. Without the renewables, the gap could extend as high as 3,865 MW (as illustrated in Table 3-3 above).14
As we have noted, additional blackstart resources and investments will be needed to fully transition to the zonal approach, and the tables we present above that reflect the
14 Using MISO accreditation values of renewables is reasonable for planning purposes but does not guarantee availability. Continued investigation is needed to incorporate the range of available levels of renewable generation and how to reliably operate them in parallel with firm dispatchable generation to accelerate the restoration process.
restoration capabilities under a full zonal approach include assumptions about resources that are not specifically reflected in our economic modeling. Given that such resources will primarily serve the purpose of system restoration, we believe a separate proceeding to more broadly discuss restoration of the Minnesota system from a catastrophic event would be appropriate, particularly in light of the increase of renewable resources throughout the state and decrease of thermal baseload units that traditionally have been relied on for such purposes. In that proceeding, we would intend to discuss the specific resources we would add to meet our system restoration needs under a zonal approach.15 As noted in our action plan, we intend to commence this proceeding in the coming years.
In the meantime, and as we discuss in more detail below, we need to make changes to some of our current blackstart units regardless of the path we take in the future.
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Beyond these Units and these Zones, we expect we will have additional needs for firm
15 We are committed to being technology-neutral as we examine these opportunities in the future.
16 The placeholder continues to be reflected in the Supplement Plan discussed in this Reply.
dispatchable generation to support the zonal restoration approach. As we have otherwise noted, we will address any further need for blackstart resources and related incremental investments in these and other Zones in a future proceeding dedicated to system restoration.