In the May 25 meeting of the Resource Adequacy Subcommittee (RASC), stakeholders were invited to submit feedback on potential non-thermal accreditation reforms for wind and solar resources - specifically application of MISO's evaluation criteria. The comment period is open through June 29 to allow participation and further insights from the June 21 workshop.
As well, stakeholders may submit additional topics and questions to be covered in the June 21 workshop via the feedback tool. MISO asks that this feedback be submitted as soon as possible to allow proper preparation for the workshop.
You may submit feedback more than once to allow comments on both requests.
Public Service Commission of Wisconsin (PSCW) Office of Regional Markets staff appreciates the opportunity to comment and provide feedback on Non-Thermal Accreditation of Wind and Solar following discussions at the May 25, 2022 Resource Adequacy Subcommittee and June 21, 2022 Workshop.
First, PSCW staff has questions about the solar accreditation value MISO is indicating in their analysis up to this point. From Slides 16 and 20 of the June Workshop, it appears solar PV’s summer season accreditation would be in the range of 30-35% across the three methodologies. MISO currently evaluates solar production based on a summer peak (approximately during the hours of 3-6pm during June, July, and August), and typically has assigned capacity accreditation in the range of 70% after the first year. Noting that MISO’s analysis is indicating half the value of the current accreditation, we pose the following questions:
Additionally, we would request more information on the assumptions of the type of solar PV this would affect and to the extent it would affect existing solar that was approved based on current accreditation assumptions:
PSCW staff would like to see answers to these questions as well as those similarly posed by Alliant Energy in their feedback to this request. We would also support requests from stakeholders for MISO to articulate their assumptions and analysis more clearly via a white paper or report rather than only in presentation format or unrecorded workshops. This is particularly important for states to review and understand the material and potential future scenarios in making current and future decisions that could affect resource adequacy. Given this, PSCW staff expects MISO to intently engage with states with each step of this review.
Xcel Energy agrees with the IMM's position that the marginal capacity value of wind and solar are expected to approach zero as the penetration increases so the residual capacity requirements will denote the dispatchable capacity requirements. For this reason, we encourage MISO to evaluate the vintaged marginal and Delta ELCC methodologies for non-thermal capacity accreditation now to ensure that the thermal and non-thermal capacity accreditation methodologies work in tandem. MISO has stated that these options could be evaluated in the design phase if warranted, but it is unclear what is required to "warrant" this inclusion.
We would also request incorporation of the ideas provided in our feedback on June 16 into the materials for the July RASC.
DTE Electric appreciates the opportunity to provide feedback on the evaluation criteria for potential non-thermal accreditation reforms for wind and solar resources.
DTE is requesting that MISO provide additional data at the Market Participant level to further evaluate the impact of each proposed methodology. While market-wide data may be indicative of the impact of proposed methodologies, it is critical for Market Participants to understand these impacts more granularly to identify potential effects on their resource fleet.
Of the options presented, and without some of the more granular data necessary to make a complete analysis, DTE believes the Blended B approach could most logically capture the impact of RA hours while still recognizing the load-carrying capability of intermittent resources. While the Blended A approach combines the RA Hour and ELCC methodologies, DTE does not find a simple weighted average to be a logical approach to combining the two methods, nor are we convinced this approach would accurately reflect the reliability benefit of these resources. With regard to the RA Hour methodology, DTE recommends differentiating between causes of curtailment by adding curtailments back in only if the resource has firm deliverability.
Comments of the Environmental Sector Following the June 21, 2022 Non-Thermal Accreditation Workshop
Issue Tracking ID#: RASC20192, RASC20204
The Environmental Sector appreciates the work MISO staff have completed to date to examine the risks posed to system operation, including potential loss-of-load events and insufficient operating reserves. As part of the RASC, MISO staff have investigated multiple ways of identifying risk periods. These include LOLE (loss of load expectation) modeling, the identification of low-margin times that put the system at risk, and more recently, a blended approach. Some of this work builds upon MISO’s annual LOLE study and its annual ELCC study for wind resources and solar resources.
However, the June 21, 2022 workshop clearly showed that MISO’s presentation of this work is too high level to be meaningful for stakeholders. Stakeholders need much more detailed information on data inputs, assumptions, and detailed methodologies for each of these studies. Specifically, MISO also needs to clarify how any processes or assumptions used for the analysis of accreditation options differ from the parallel analyses run each year, such as the annual LOLE study.
Stakeholders want to support MISO’s work on wind and solar capacity accreditation and find a reasonable, workable solution. However, by not providing detailed data, assumptions, and explanations of methods used in written form, either as a white paper or a robust Frequently Asked Questions document, MISO risks creating continued confusion and repeating stakeholder frustration, and ultimately risks litigation at FERC. We prefer that MISO take a step back and take the time needed to produce these materials, sharing them with stakeholders before moving forward. If this means wind and solar accreditation discussions at the RASC need to be delayed, we support that time being taken to enable much more productive discussions moving forward. Whether MISO provides a white paper or a robust Frequently Asked Questions, it will be important to provide information to stakeholders at varying technical levels, from detailed formulas and data in spreadsheets, to higher level narrative explanations of the analysis methods.
Respectfully submitted on behalf of the Environmental Sector,
Mike Schowalter
Fresh Energy
The IPP Sector thanks MISO and its Staff for their efforts to investigate capacity resource accreditation for non-thermal resources. As a group, we appreciate that solutions in this space can be complicated. The complications here are further compounded by uncertainty surrounding the framework of MISO’s capacity construct; continuing as annual or transitioning to seasonal as proposed in FERC docket ER22-495.
The IPP Sector is concerned that MISO is committing substantial resources to develop a non-thermal accreditation construct under the assumption the Seasonal Accredited Capacity (SAC) construct will be approved as-filed. MISO Staff and stakeholders must be in a position to quickly pivot to react to any FERC Order on the SAC construct. Considerations for annual accreditation, seasonal accreditation, relying on UCAP, and relying on SAC should be included in future work. The IPP Sector is also supportive of relying on the same capacity accreditation methodology for all resources. The proposed SAC methodology accounts for correlated risks on a historical basis, but fails to do so on a going-forward basis. The IPP Sector encourages MISO to address both of these issues within the current initiative.
All IPP Sector members agree that more information is needed for regulators and stakeholders to understand the impact of MISO’s RA Hour and Blended proposals. At present, stakeholders have been provided with a high-level review of four (4) methodologies and some preliminary results. With technical studies like these, the details of the methodologies matter because the underlying assumptions drive the results. Absent a fulsome understanding of all the underlying assumptions, stakeholders cannot develop the needed expertise to inform the strategic decisions that ultimately impact MISO’s Resource Adequacy Construct. For example, (a.) we do not know if newer inverter-based resources are assumed to perform better than older ones. (b.) We do not know how MISO is modeling future occurrences of extreme weather events and how those drive RA Hour identification. (c.) We do not know how MISO is modeling future penetration from gas resources. (d.) We do not know the weights that are being applied to historical performance verses expected future performance. All these details matter. The IPP Sector asks MISO to publish these assumptions and accept stakeholder feedback on the reasonableness of those assumptions.
In a similar vein, a lesson from MISO’s finalization of the SAC proposal, IPP members need to understand unit-specific impacts of accreditation proposals well in advance of the production of the final Tariff revisions. Again, these accreditation issues inform the strategic and commercial decisions of our Sector which, in turn, effect the Resource Adequacy condition of the MISO system. Rather than having a rush to the finish like we did last fall leading up to the SAC Proposal filing at FERC, the IPP Sector asks MISO to begin providing unit-specific evaluations as soon as practicable. If MISO is unable to provide those unit-specific evaluations, the IPP Sector asks MISO to share a draft model that would allow for a facility to input its capability and performance data to determine its own capacity accreditation.
But timing is critical to this process. A review of the timeline indicates that MISO is looking to conclude conceptual design discussions with stakeholders in the immediate term and present the design criteria in August. Then MISO will review preliminary results in October with final conceptual design results being reviewed in November.
It was previously communicated that MISO would like to submit Tariff revisions to FERC as early as January 2023. To the IPP Sector, one month is not enough time to review preliminary results and then stamp them as final. Although MISO has limited rules around the formality of the stakeholder process, the IPP Sector encourages MISO to take advantage of the industry expertise within the collective stakeholder body. By providing a little bit more room at the end of the runway, MISO can submit a consensus-based package to FERC that is reflective of robust stakeholder refinement and has a high likelihood of near-term approval.
City of Ames, AMP, MPPA, MRES, and SMMPA generally support WPPI's post-workshop feedback.
David Sapper
dsapper@ces-ltd.com
The Entergy Operating Companies ("EOCs")[1] appreciate the opportunity to provide feedback on MISO’s evaluation of potential non-thermal accreditation reforms.
The June 21, 2022 workshop clearly showed that MISO’s presentation of this work is too high level to be meaningful for stakeholders. Stakeholders need much more detailed information on data inputs, assumptions, and detailed methodologies for each of these studies, preferably in written form such as a white paper. Specifically, MISO also needs to clarify how any processes or assumptions used for the analysis of accreditation options differ from the parallel analyses currently run each year, such as the annual LOLE study and the wind capacity credit study.
In addition to providing MISO-wide accreditation study results, the EOCs request that MISO provide results to stakeholders showing accreditation impacts at the zonal and individual unit level.[2] In particular, the EOCs would like to see how the unit level accreditation values are projected to vary from one planning year to the next, allowing MISO and stakeholders to assess the stability of each accreditation method. Without this zonal and unit level data, MISO and stakeholders will not be able to accurately evaluate the proposed accreditation methods.
The EOCs also believe that further analysis and discussion is needed related to the treatment of curtailed wind and solar in the accreditation process.
Since the last RASC meeting, but prior to the June workshop, the EOCs submitted feedback on this same topic. That feedback is included below for completeness.
“The EOCs are concerned that MISO’s proposed analysis of the RA Hours Method for future system resource portfolios is not consistent with how the RA Hours Method would actually work if implemented. This is due to the fact that the RA Hours Method relies on recent historical system data to determine relevant RA Hours and it relies on recent historical individual unit performance data to determine resource availability during those RA Hours. Given that we don’t have historical system and resource operational data for future resource portfolios, it is not feasible to use the RA Hours Method to evaluate a future resource portfolio mix as MISO is proposing. For this reason, the EOCs believe that MISO’s proposed analysis will not produce meaningful insights into the RA Hours Method and may actually produce deceptive results which will mislead stakeholders understanding of the RA Hours Method’s true impact on non-thermal accreditation.
Instead of applying the RA Hours Method to a future resource portfolio MISO should apply the RA Hours Method to the existing MISO resource portfolio, which is what MISO did when evaluating the RA Hours Method (also known as SAC) for thermal resources during last year’s seasonal construct stakeholder process. The existing MISO resource portfolio has the necessary historical operational data to use the RA Hours Method and would allow for a much more meaningful analysis.
In the event that MISO continues with their proposal to evaluate the RA Hours Method on future portfolios, despite the EOCs above stated concerns, the EOCs believe that the decision MISO makes on solar and wind profile modeling is very important. In order to accurately understand how the RA Hours Method will impact the accreditation of individual resources, MISO should model individual wind and solar resources with unit level output profiles that correspond to a variety of weather conditions. In contrast to this approach, the EOCs do not want MISO to apply aggregated, weather-normal profiles to individual wind and solar units because this approach will not accurately demonstrate how individual solar and wind units accreditation will be impacted by the RA Hours Method.”
[1] The Entergy Operating Companies are Entergy Arkansas, LLC, Entergy Louisiana, LLC, Entergy Mississippi, LLC, Entergy New Orleans, LLC, and Entergy Texas, Inc.
[2] Individual unit level data should be anonymized and could be presented similar to Figure 3-3 of the 2022 Wind and Solar Capacity Credit report.
Clean Grid Alliance Comments
MISO’s Non-Thermal Accreditation Workshop
Clean Grid Alliance (CGA) appreciates the work MISO has done so far to evaluate potential options for adjustments to its wind and solar accreditation as well as the opportunity to submit these comments following the June 21st workshop. We also welcome MISO’s plan to add a storage sensitivity to its Future 1-2025 resource portfolio replacing 10 GW of new thermal capacity with 10 GW of battery capacity to test the robustness of the results. Below, we provide additional clarifying questions and input on what MISO can do to help stakeholders understand its assumptions and methodologies in this effort, and suggestions for adjustments to the accreditation methodologies MISO is evaluating.
We concur with the request submitted by the Environmental Sector for MISO to take a step back and provide more detailed information on the assumptions and methodologies used in MISO’s existing ELCC based accreditation methodology, and the multiple methodologies currently being evaluated in the process. This could be provided in the form of a white paper or FAQ document. Strong stakeholder understanding is critical for support of this process and the ultimate non-thermal accreditation methodology MISO will file with FERC. As well, it would be helpful for MISO to provide its raw data inputs/set such that stakeholders can review these and provide appropriate feedback. Without a thorough understanding by stakeholders, MISO is likely to see the same kind of resistance that happened at the end of the SAC proposal process when stakeholders did not feel that they fully understood MISO’s proposal or methodologies.
We recognize this could mean that wind and solar accreditation discussions at the RASC and the final proposal are delayed relative to MISO’s plan to file a proposal with FERC at the end of 2022. We support taking that time as a critical foundation to the ultimate success of this proposal. We also suggest that additional workshops would be helpful to provide for stakeholder dialog and engagement with this detailed and highly technical issue.
Other facts support slowing the pace of the non-thermal accreditation review as reasonable. First, MISO still has not received a ruling from FERC on its SAC proposal, and SPP has recently received its second deficiency letter from FERC suggesting that the Commission considers comparable treatment of different resource types important. Progress in both of these other proceedings would be informative for this MISO stakeholder process on wind and solar accreditation. For these reasons, slowing the pace of the non-thermal accreditation review is a reasonable step that can facilitate acceptance of the final proposal.
We also request that MISO provide a side-by-side comparison of the Schedule 53 accreditation approach for thermal resources with the various accreditation methods under consideration for wind and solar so that stakeholders can easily consider whether the approaches for thermal and non-thermal resources meet the comparability criteria. Comparable does not necessarily mean that accreditation methodologies are exactly the same, but MISO and stakeholders need to have transparency around any differences to determine if they can still result in comparable accreditation for all resource types. This side-by-side comparison should include consideration of whether each approach evaluates both correlated and uncorrelated outages of the resource types. Additionally, we request MISO provide details on the exemptions for RA hours for thermal resources and what similar exemptions they might apply to non-thermal resources.
MISO’s “Blended A” approach uses an arbitrary 50/50 split for the weighted average of the ELCC and RA Hours approaches. ELCC is highly dependent on future resource mix and thus has greater uncertainty. Thus, we believe that MISO should consider the Blended A approaches with weighted averages that place more emphasis on the RA Hours approach. For example, MISO should evaluate 70% RA hours/30% ELCC, and 80% RA Hours/20% ELCC splits, and possibly others. Because all of these splits at this time seem arbitrary, MISO should consider how it will justify any split that is ultimately chosen for wind/solar accreditation. We also note that the current blended approach in effect for thermal resources is weighted at 100% RA hours and 0% ELCC. Therefore, using the RA Hours approach alone is more likely to meet the comparability test, and the use of any other approach must be well justified.
For the “Blended B” approach, we request that MISO explain how adding the high-risk hours identified in the LOLE methodology to the RA hours used in the historic look back approach to determine capacity availability of a resource does not result in an arbitrary set of additional hours. The hours identified in the LOLE approach may not be at all related to the temperature, load, and risk on that same day in the three historic years being evaluated, or to any high-risk hours in those historic years.
MISO notes on slides 19-20 of the June 21st presentation that applying the individual ELCC method to wind and solar accreditation neglects the resources’ complementary interaction, leading to lower capacity credits than compared to the portfolio ELCC method. This result was also noted in the RIAA analysis. For the ELCC approach, we therefore request that MISO evaluate the capacity accreditation of wind and solar using the portfolio approach which is a more realistic analysis, given that we will have both resource types on the MISO system.
In response to stakeholder comments that MISO should be using a marginal ELCC approach, we respectfully disagree. Thermal resource accreditation is not done on a marginal basis today or under the SAC proposal. Average ELCC is appropriate for accrediting resources to ensure that all resources are treated comparably with regard to the capacity they provide in meeting the Planning Resource Margin in the prompt year, and it meets MISO’s stated aim of providing balance between stability and accuracy in accrediting resources.
Please feel free to reach out to us if you have any questions about this input. We look forward to the continuing dialog on this topic.
Respectfully submitted for Clean Grid Alliance,
Natalie McIntire
Minnesota Power appreciates the work MISO staff have completed to date to examine a range of options to quantify the accredited capacity for wind and solar resources. MISO staff have investigated multiple ways of identifying risk periods. These include seasonal LOLE (loss of load expectation) modeling, the seasonal identification of low-margin hours that put the system at risk(RA Hours), and more recently, a blended approach. Some of this work builds upon MISO’s annual LOLE study and its annual ELCC study for wind resources and solar resources. The analysis using the RA Hour approach builds upon the Seasonal Accredited Capacity SAC approach per docket FERC Docket ER22-495.
However, the June 21, 2022 workshop clearly showed that MISO’s presentation of this work is too high level to be meaningful for stakeholders. Stakeholders need much more detailed information on data inputs, assumptions, and detailed methodologies for each of these studies. Specifically, MISO also needs to clarify how any processes or assumptions used for the analysis of accreditation options differ from the parallel analyses run each year, such as the annual LOLE study. MISO also needs to clarify how RA Hours can be identified for resources with no operating history.
Stakeholders want to support MISO’s work on wind and solar capacity accreditation and find a reasonable, workable solution. However, by not providing detailed data, assumptions, and explanations of methods used in written form, preferably as a white paper, MISO risks not clearing up the current confusion and repeating stakeholder frustration, and ultimately litigation at FERC. We prefer that MISO take a step back, take the time needed to produce these materials and share them with stakeholders before moving forward. If this means wind and solar accreditation discussions at the RASC need to be delayed, we support that time being taken to enable much more productive discussions moving forward.
Response of the Solar Energy Industries Association
The Solar Energy Industries Association (SEIA) appreciates MISO for accepting stakeholder feedback on MISO’s May 25, 2022 presentation on Accreditation Reforms for Non-Thermal Resources. SEIA notes that this feedback also takes into consideration presentations made to the Board of Directors and the June 21, 2022, Non-Thermal Accreditation workshop. SEIA highlights the importance for MISO to share more details about the methodology and calculations used for each iteration of MISO’s ongoing effort to develop a revised capacity accreditation methodology for non-thermal resources. It is of critical importance that stakeholders and regulators understand how MISO is arriving at the results of the modified effective load carrying capability (ELCC) and “Blended” analysis. Merely evaluating the results of MISO’s analysis provides some insight as to the practical implications of the proposals but falls short of providing stakeholders with the details necessary to fully appreciate key drivers. With that, SEIA asks MISO to publish all of the underlying assumptions it is using for the ELCC, RA Hour, and Blended methodologies.
More specifically, SEIA requests MISO to provide clarification as to how the Blended Approach will assign capacity values to specific resources. The May 25 and June 21 presentations indicate the approach would incorporate historical performance and probabilistic future scenarios, but the presentation presents little detail on the weight that will be given to those factors. SEIA is concerned that an over-reliance on historical data will not capture the impacts of the increasing extreme weather events. SEIA is also concerned that over-reliance on unrealistic or outdated futures could cause a disconnect between resource performance and accreditation.
Separately, if MISO selects either the ELCC Methodology or the Blended Approach, SEIA urges MISO to include weather data that reflects extreme weather events. Over the last several years MISO has observed an increase in extreme weather conditions that strain the system. With climate change, these extremer events are expected to increase in intensity and frequency.[1] MISO needs to incorporate these events into its models to ensure there are sufficient resources to reliably serve load during these extreme events. MISO’s future scenarios also need to accelerate the expected occurrences of such events because historical data will underrepresent expected future occurrences and the associated risks.
SEIA again urges MISO to create uniformity in the capacity accreditation methodologies that are applied to the various technology types. The same resource accreditation methodology is needed for both non-thermal and thermal resources. Industry experts have recognized that while “[t]here is no such thing as perfect capacity,” all resources (“beyond just wind, solar, & storage”) should be subject to a similar accreditation methodology.[2] MISO’s current practice of resource accreditation for thermal resources will continue to fail to account for outages, fuel availability, or correlated thermal resource risks. This sits in stark contrast to the scrutiny for renewable technologies and the capacity devaluations applied to value of wind, solar, and energy storage resources (ESRs) on a fleet-wide basis. The creation of a ELCC or similar capacity accreditation methodology that applied to all resources will address MISO’s current issues of (1) overvaluing thermal resources that fail to meaningfully contribute to the current resource adequacy needs and (2) undervaluing the contributions of renewable resources.
[1] Exploring the Impacts of Extreme Events, Natural Gas Fuel and Other Contingencies on Resource Adequacy, EPRI, January 28, 2021, available at, https://www.epri.com/research/summary/000000003002019300. See also, The February Artic Event, MISO, available at https://cdn.misoenergy.org/2021%20Arctic%20Event%20Report554429.pdf (identifying increasing risks associated with more frequent extreme weather).
[2] Redefining Resource Adequacy for Modern Power Systems – ESIG November Webinar, Telos Energy (“Nov. 16, 2021), available at: https://www.esig.energy/download/redefining-resource-adequacy-for-modern-power-systems-2/?wpdmdl=8346&refresh=619510278817a1637158951.
Solar capacity should decrease over time as the amount of distributed solar generation increases. Distributed solar looks like negative load to the transmission system and shifts the peak to later in the day when solar output is declining. In the past MISO had assumed a 2% per year decrease in the capacity value of solar.
Duke Energy Indiana (“Duke”) appreciates the chance to share our thoughts on MISO’s proposal introduced in the May 25 RASC meeting and subsequent June workshop. Stakeholders were invited to submit feedback on potential non-thermal accreditation reforms for wind and solar resources - specifically application of MISO's evaluation criteria (Issue Tracking ID#: RASC2019-2, RASC2020-4). Duke’s comments are as follows:
WEC Energy Group shares Alliant's concerns with the potential for significant decreases in the summer accreditation of solar resources. As noted by the graphs on slide 16 of the workshop presentation, solar provides capacity values of approximately 60% during hours 12 through 16 under both the tight margin and simulated loss of load hours approach. Outside of those hours, solar capacity values drop off with the diminishing solar intensity. We believe that the solar accreditation methodology needs to recognize the value of solar over those summer hours while also ensuring that other types of resources are available during those hours and seasons when solar output is much lower. We believe that the seasonal RA construct will provide some value in differentiating the value of solar in different seasons. However, even within the summer season, the capacity value of solar needs to represent its diurnal nature to ensure it is credited with its ability to serve load over the early afternoon hours while ensuring that other types of resources are available during the evening and night hours. Perhaps we need to think of solar accreditation in terms of its ability to serve the typical summer peak load while recognizing that solar may not provide that same capacity value during tight margin hours (Tier 2 hours - whether forecasted or based on historical observations, as noted on slide 12 of the workshop presentation).
WEC Energy Group agrees with the comments from other stakeholders that more detailed information on simulation inputs, assumptions, and methodologies (and perhaps a white paper) will encourage comprehension, discussion and debate.
WPPI reiterates our comments submitted June 13 and posted June 16. We join the comments submitted by Mike Schowalter of Fresh Energy on behalf of the Environmental Sector. We offer the following additional comments:
Alliant Energy is concerned that MISO’s proposed methodology severely undervalues solar summer accreditation. Slide 16 of the June 21, 2022 presentation indicates solar accreditation rates in the low to mid-thirties as a percentage of nameplate/ICAP. This is half the value LSEs are currently expecting through existing accreditation rates of 50% for first year and 60-70% based on average summer afternoon hours (15-17 EST Jun-Aug). Moreover, in a September 2021 RAN Renewable Impact Analysis presentation, MISO estimated a solar summer accreditation rate of ~65% (237 MW historical performance on 362 MW ICAP).
Alliant Energy cautions MISO that drastic accreditation rate changes are a concern due to the lead time needed for LSEs to adjust their resource plans, and drastic accreditation rate changes combined with short implementation schedules are unworkable.
We would appreciate answers to the following questions regarding the low solar summer accreditation rates relative to what can be obtained today, prior to the July workshop, in the interest of time:
Comments to MISO’s RASC Re: Non-thermal Accreditation
June 16, 2022
Clean Grid Alliance appreciates the updates on non-thermal accreditation MISO presented at the May RASC meeting and the opportunity to provide comments prior to the June workshop on non-thermal accreditation. We look forward to learning more at the workshop and may also submit additional comments after that.
First, we want to note our appreciation of MISO’s addition of “comparability” to the list of criteria that will be used to evaluate options for wind and solar accreditation methodologies. This is important both to ensure that MISO’s accreditation methodologies are non-discriminatory, and that the capacity construct is internally consistent and will result in sufficient capacity available to meet load in high-risk hours. All resources should be accredited based on a common set of risks and reliability hours. The MISO proposals for wind and solar resource accreditation appear comprehensive and rigorous, however, these methods are not congruent with Schedule 53 accreditation practices, and therefore fail any reasonable comparability test and may be viewed as unduly discriminatory at FERC. CGA members request additional information on how MISO will ensure comparability in resource accreditation despite the substantial differences in risk considerations for thermal and non-thermal resources. For example, the proposed blended approach for non-thermal accreditation considers correlated risks from weather on a historical and projected basis. The pending accreditation process for Schedule 53 resources does not consider projected correlation risks from weather (temperature/droughts) or energy constraints driven by fuel contracts and pipeline capacity limitations. The discrepancy between accreditation methodologies over accredits Schedule 53 resources and exposes MISO customers to a latent reliability risk. We also request MISO provide in its June 21st workshop details on how it plans to use all the criteria listed to evaluate accreditation methodologies.
Second, we would like to see MISO provide more clarification on exactly what the blended approach or approaches would be. In the May presentation, it seemed MISO was suggesting it is considering more than one way to blend the ELCC and RA Hours approaches. Detailing these possible ways to blend the ELCC and RA approaches would be helpful. In particular, MISO’s presentation suggested that RA Hours largely occur on different days than LOLE hours. Does this indicate that the RA Hours approach may be a poor predictor of capacity availability in the future? Please provide further discussion on how the fact that the RA and LOLE approaches result in different high-risk hours relates to which approach is more appropriate, or why using a blended approach of both would be most appropriate.
Lastly, we agree with MISO that evaluating the accreditation options with three different resource mixes may be helpful and using a resource mix that represents the near-term is a good addition. We do not agree that MISO’s three resource mixes represent what we would expect to see under various future conditions. Many stakeholders agree the lack of storage in Portfolios 1 and 2 is concerning, and we would argue that even the amount of storage in Portfolio 3 is not sufficient. There are also concerns about the levels of electrification and relative balance between wind and solar. There is substantial uncertainty implicit in both the ELCC and RA Hour approaches. The ELCC calculations in particular are highly dependent on assumptions about the underlying future resource portfolios. Since MISO’s proposed potential future portfolios used to infer the ELCC do not robustly cover the range of potential futures, the ELCC analysis can incorrectly limit the potential capacity contribution of resources and result in unduly discriminatory treatment about what could, but might never happen. The resource mixes used in the ELCC analysis will impact the results on prospective approaches to accreditation and this will mean that those results should have limited applicability to non-thermal accreditation. Similarly, a backward-looking RA Hours approach that focuses on past performance will not reflect the risks of fleet evolution. That being said, the RA Hours approach is a critical component of closing the gap between the current system and the future power system. Given the relative uncertainty between the RA Hour and ELCC based methods, any blended accreditation construct should rely more heavily on RA hours and less on ELCC. We suggest MISO consider a 60/40 split in the blending of the approaches as a reasonable starting point, with 60% of the weighting being given to historical RA hours.
Please reach out to us if you have any questions about these comments. We would welcome further discussion.
Respectfully submitted,
Natalie McIntire
Consultant for Clean Grid Alliance
Comments on Accreditation Reforms for Non-Thermal Resources
Submitted by: MISO Environmental Sector
June 14, 2022
The Environmental Sector appreciates the opportunity to submit this feedback on MISO’s May 25, 2022 presentation on Accreditation Reforms for Non-Thermal Resources. We also appreciate that MISO has responded to prior feedback by adding “comparability” to the list of criteria to be used to evaluate capacity accreditation options for wind and solar technologies. We look forward to the June 21, 2022 workshop of the Resource Adequacy Subcommittee (“RASC”) as more discussion is needed to help stakeholders understand the options under consideration and their implications for wind and solar accreditation.
To support a robust dialogue and comprehensive examination of accreditation methodology options, the Environmental Sector has the following requests of MISO.
1. We ask that MISO conduct and share a root-cause analysis for risk hour identification between the ELCC and RA hour methodologies that were presented in the May 25, 2022 RASC meeting. MISO should identify system conditions present in each simulation that led to risk materializing. RA hours realized in real time may have different causes than risk hours materializing in an ELCC study. Importantly, both assessments may be reasonable and therefore should be captured in a blended approach. But without understanding the root causes of system risk that materialize in each study, stakeholders and MISO have no way to determine the optimal blended approach.
This analysis should be conducted across all three of the Portfolio scenarios and shared transparently with data posted to MISO’s website for stakeholders to examine. It is critically important to conduct this root cause analysis across multiple resource mixes to ensure the final method employed for non-thermal accreditation is robust against resource mix change and will not need to be revisited in the near future.
Ideally, MISO would bring some or all of this root-cause analysis to the June 21, 2022 workshop.
2. We ask that MISO provide more clarification on how a “blended” accreditation approach (slides 9, 12) would be developed. Discussion at the May 25, 2022 RASC meeting seemed to indicate there may be multiple “blended” methods that could capture both ELCC and RA Hour approaches. MISO’s analysis to date has shown that these two methods identify different risk hours. We urge MISO to provide further discussion on how a blended approach may be more appropriate than just an ELCC or RA Hour approach. Options to weight the LOLE and RA hours based upon either LOLE or margin shortage should be subject to robust discussion with stakeholders, along with all other details of the blending process.
3. We ask that MISO provide much more clarity on how each evaluation criterion (slides 6, 21) will be used to evaluate accreditation methodology options, especially since only one of the options listed for accreditation would match the methodology already filed at FERC for thermal resources (Docket No. ER22-495).
4. Lastly, we ask that MISO explore how the three resource portfolios, and, within each portfolio, the interactive ELCC effects among wind, solar, storage, load, etc. impact forward-looking accreditation values, which are used in state and utility planning processes. We are concerned that as designed the three portfolios may not be realistic, and we describe that below. In addition to these requests, we note that we remain concerned about comparability between thermal and non-thermal resource accreditation. Moreover, we remain concerned that the use of ELCC must be appropriately conducted with reasonable/realistic assumptions and high-quality input data.
We agree with and support MISO’s decision to evaluate accreditation methodologies across multiple resource mixes, and that using a near-term resource mix (Portfolio 1) is a good addition. However, the resource mixes in the three portfolios may not provide a realistic view of the future. Specifically, there is not enough storage in any of the Portfolios (including the 35 GW of storage in Portfolio 3) to align with expected reality. Adding more storage in the resource mix will change system dispatch patterns and therefore risk profiles. Storage may solve or exacerbate risk, but without realistic levels of storage in the resource mix, those effects won’t be well understood.
We urge MISO to discuss with stakeholders exactly how storage is dispatched in the SERV-M model or any other models being used for this analysis, and to explore how the inclusion of storage in the resource mix may change risk profiles. This could be done as a sensitivity to Portfolio 1 or 2.
Thank you for considering this feedback. The Environmental Sector looks forward to continued discussion during and after the June 21, 2022 workshop.
Xcel Energy believes the following material and discussion would be beneficial for the June 21 workshop, based on the graphics provided on slide 20 of the non-thermal capacity accreditation deck presented at the 5/25 RASC:
Thank you.
WPPI Energy offers the following initial thoughts on MISO's non-thermal resource presentation from the May RASC meeting:
We reiterate our request from the May 25 meeting that MISO avoid using ‘LOLH’ to refer to specific hours in which loss of load occurred in some iteration of Monte Carlo analyses, as this is an established abbreviation for a different concept: the expected number of hours in which loss of load occurs, as used by MISO in its annual LOLE Study Report. Please consider using LOL Hours instead.
We are finding it difficult to discern what MISO is trying to accomplish via its current analysis. We would request that MISO lay out the fundamentals of the analysis it is conducting, and the corresponding goals, to better allow stakeholders to understand that analysis.
MISO shows the results of RA Hours and LOLE analyses on slide 17 of its May 25 presentation in which RA Hours are compared to LOL Hours, apparently leading to a MISO conclusion that these hours tend not to coincide. This conclusion appears misplaced to us, since it is (as we understand) based on historical RA Hours but a future simulation of LOLE analysis, which is very different from the ELCC accreditation that MISO applies today. Unless MISO is proposing to abandon the current ELCC methodology that relies on historical load and corresponding historical wind-output data (something we are not aware that MISO has communicated and that would require significant discussion), this comparison appears not apt to assessing the relative benefits of LOLE and RA Hours approaches.
We would appreciate MISO providing an explicit explanation of the differences between these approaches, as MISO understands them, to facilitate discussion. For example, as we understand it, the ELCC approach may be superior to the RA Hours approach in that it weights hours it identifies with a measure of the severity of the potential shortage, whereas the RA Hours approach weights all identified hours equally, thus failing to distinguish between potential shortages of different severity. In contrast, we understand that the RA Hours approach accounts for actual historical planned generation outages, whereas the ELCC approach may not. It may be that we can change aspects of each of these approaches, or combine elements of these approaches, and that this may provide benefits that we would not consider without such discussion.
The evaluation criteria should be based on (i) the ability of a method to accurately represent resources’ expected contribution to load-carrying capability; (ii) practicality of implementation; and (iii) understandability for MISO and stakeholders. Accreditation per se should not be expected to ‘ensure sufficient capacity in the planning horizon [] to maintain reliability.’ We are wary of the notion that accuracy should be sacrificed to accommodate stability goals or to achieve comparability with other methods that may be less accurate. We are skeptical of the need to expend significant effort on analysis of different resource portfolios, since this appears to be of only second-order importance for evaluating accreditation methods’ ability to accurately represent contributions to resource adequacy.
To the extent that MISO sees the need to ensure that accreditation accounts for possible failure to accurately anticipate demand and to commit sufficient resources in the Day-Ahead and RAC processes, where such failure could result in material LOL risk, we are inclined to think that this should be addressed primarily via changes to MISO’s unit-commitment operations rather than via resource accreditation. At a minimum we would want to see an analysis showing that MISO’s current commitment practices are economical, when considering outage risk, before we would see it appropriate to consider this in resource adequacy.
We would suggest that the above comments would be useful for MISO to consider in preparing materials for the June 21 Workshop.
City of Ames, AMP, and MPPA generally support WPPI Energy's feedback.
Thanks,
David Sapper
dsapper@ces-ltd.com
The Entergy Operating Companies ("EOCs")[1] appreciate the opportunity to provide feedback on MISO’s evaluation of potential non-thermal accreditation reforms.
The EOCs are concerned that MISO’s proposed analysis of the RA Hours Method for future system resource portfolios is not consistent with how the RA Hours Method would actually work if implemented. This is due to the fact that the RA Hours Method relies on recent historical system data to determine relevant RA Hours and it relies on recent historical individual unit performance data to determine resource availability during those RA Hours. Given that we don’t have historical system and resource operational data for future resource portfolios, it is not feasible to use the RA Hours Method to evaluate a future resource portfolio mix as MISO is proposing. For this reason, the EOCs believe that MISO’s proposed analysis will not produce meaningful insights into the RA Hours Method and may actually produce deceptive results which will mislead stakeholders understanding of the RA Hours Method’s true impact on non-thermal accreditation.
Instead of applying the RA Hours Method to a future resource portfolio MISO should apply the RA Hours Method to the existing MISO resource portfolio, which is what MISO did when evaluating the RA Hours Method (also known as SAC) for thermal resources during last year’s seasonal construct stakeholder process. The existing MISO resource portfolio has the necessary historical operational data to use the RA Hours Method and would allow for a much more meaningful analysis.
In the event that MISO continues with their proposal to evaluate the RA Hours Method on future portfolios, despite the EOCs above stated concerns, the EOCs believe that the decision MISO makes on solar and wind profile modeling is very important. In order to accurately understand how the RA Hours Method will impact the accreditation of individual resources, MISO should model individual wind and solar resources with unit level output profiles that correspond to a variety of weather conditions. In contrast to this approach, the EOCs do not want MISO to apply aggregated, weather-normal profiles to individual wind and solar units because this approach will not accurately demonstrate how individual solar and wind units accreditation will be impacted by the RA Hours Method.
[1] The Entergy Operating Companies are Entergy Arkansas, LLC, Entergy Louisiana, LLC, Entergy Mississippi, LLC, Entergy New Orleans, LLC, and Entergy Texas, Inc.