In the November 30, 2022, meeting of the Resource Adequacy Subcommittee (RASC), MISO shared detailed recommendations for non-thermal accreditation. Written feedback was requested on the recommendation for wind and solar accreditation.
Comments are due by December 21.
Ørsted Comments on RASC: Wind-Solar Accreditation Recommendation (RASC-2020-4, RASC-2019-2) (20221130)
December 21, 2022
Ørsted values the opportunity to comment on MISO’s proposal for capacity accreditation of wind and solar resources.
We recognize the importance of the topic, as appropriately accounting for the contribution of these resources to regional and sub-regional resource adequacy is key to reliably transitioning towards greener generation. We look forward to contributing to the development of resource accreditation methods that ensure adequate generation is available when needed, without forcing load serving entities to over procure capacity or preventing some resource classes from being compensated for their contribution to reliability.
Our comments regarding the proposed wind and solar capacity accreditation are focused on two areas: the use of availability during loss of load events as a representation of the contribution to reliability of a resource and the comparability between the proposed capacity accreditation for wind and solar generation with the accreditation of other types of resources.
1. Direct Loss of Load (LOL) does not adequately represent the contribution of resources to meet the reliability target
The contribution to reliability of each megawatt of installed capacity varies for different resources. If the effective capacity of a resource is its contribution towards achieving the desired reliability target, we believe that the Effective Load Carrying Capability (ELCC) of a resource is a reasonable approach to estimating such effective capacity.
At the wind and solar capacity accreditation discussions in January of 2022, MISO defined ELCC as “the amount of incremental load a resource […] can dependably and reliably serve, while considering the probabilistic nature of generation shortfalls and random forced outages”. MISO stated that the ELCC is calculated by isolating the resource(s) for which the ELCC is evaluated, and that this was “accomplished by calculating the LOLE of the system for two different cases: one “with” and one “without” the resource”[1].
Conceptually, the average ELCC calculation (Method 1[2]) is consistent with the above definition and, in our view, an adequate representation of the effective capacity of the existing wind and solar generators that will be available for the prompt-year Planning Reserve Auction (PRA).
The Direct LOL (Method 4) approach that MISO has recommended[3] is fundamentally different. It does not represent the load that aggregated wind or solar resources can serve, but rather, the volume of those resources that remain online during loss of load events in the probabilistic simulation used to compute the LOLE.
The capacity accreditation of a resource should be based on its contribution towards maintaining the reliability target, that is, its contribution towards avoiding loss of load events, as opposed to its availability during the loss of load events that do occur in the model.
MISO presentations have suggested that the proposed accreditation approach yields results that are similar to ELCC calculations. However, because of the fundamental differences between the proposed wind and solar capacity accreditation and the actual contribution of such resources towards maintaining the reliability target, we believe these results may not hold for different conditions. Consequently, the Direct LOL approach:
LOLE studies are a widely used engineering tool for evaluating planning reserves needs, even if we recognize that they are not an adequate tool to evaluate other reliability measures, such as the duration or severity of loss of load events. We caution against using the LOLE model to extract results beyond planning reserves requirements without careful technical evaluation.
2. The proposed accreditation approach is not comparable across technologies
The class-level accreditation for thermal resources is the aggregated unforced capacity (thermal UCAP). The corresponding number for wind and solar resources would be their average availability during all hours.
The use of a probabilistic class-level accreditation of wind and solar resources results from the assumption that their availability within class is strongly correlated. That is a reasonable assumption, particularly if geography and technology are considered. The converse, that the availability of thermal generators is not correlated, is not necessarily true and, in fact, has led in various areas of the country to failures and near misses during extreme weather events when fuel supplies have been limited.
Considering correlation in the availability of resources for some types of resources and not for others is not only discriminatory, but, as we learned in 2008 in the case of financial products, failing to adequately account for correlated failures may lead to underestimating risk.
Ideally, probabilistic models should be used to determine the class level accreditation of all types of resources.
While the proposed wind and solar class-level accreditation methodology might be computationally simpler than an ELCC calculation for each resource class, we believe that the ELCC is a better representation of a resource’s effective capacity. We should take advantage of existing computational capabilities to manage the increasing variability of generation and demand.
Alternatively, if a simple approach is needed, we believe that accreditation based on availability during historical high-risk intervals is preferrable to one based on availability during simulated loss of load events.
In addition to addressing the comments above, we ask MISO to:
Please feel free to reach out to us with any question regarding these comments and requests.
[2] Market Redefinition: Accreditation Reforms for Non-Thermal Resources - Design Workshop (September 21, 2022)
[4] Market Redefinition: Accreditation Reforms for Non-Thermal Resources - Design Workshop (September 21, 2022)
[5] Slide 8 on the presentation Market Redefinition: Accreditation Reforms for Non-Thermal Resources - RASC (November 20,2022) shows the comparison between the recommended method and existing ones, but not across proposed methods.
Wind and Solar Accreditation Comments to MISO
The Public Consumer Advocate Sector appreciates the opportunity to comment on MISO’s developing approach to capacity accreditation generally and on the accreditation of wind and solar resources specifically (see endnote [1] for Sector members abstaining to this submission and an additional comment).
It is very important that MISO assure resource adequacy for customers served by MISO’s load-serving entities. We appreciate that MISO is working diligently to rethink its traditional approaches to resource adequacy to reflect current and future challenges as capacity margins tighten and the technology mix in the resource portfolio evolves. At the same time, it is important that MISO not inadvertently drive investment in excess resources and resources than may become obsolete or underutilized, thereby increasing rates for consumers. It is also important that MISO’s resource adequacy construct be technology neutral and reflect actual resource adequacy requirements rather than excessively guide technology selection by utilities and their state regulators.
We are supportive of MISO’s general focus on building resource adequacy around the need to ensure adequate resources at the times when resources are tight, rather than the traditional focus on peak demands. When almost all resources were fuel-based, dispatchable, and generally had their worst performance in summer at the time of peak loads, a focus on annual demand peaks may have been sensible, although, even then, the actual shortage periods would occur at other times due to factors like scheduled maintenance and weather-driven correlated outages. Now, with increasing use of renewables and with generally tighter resource margins making factors like scheduled maintenance a more important factor, it is necessary to evolve the resource adequacy construct.
We have several questions or concerns about the approach MISO has recently presented, including in the November RASC meeting.
1. MISO appears to be trying to address two distinct aspects of resource adequacy with a single approach. On the one hand, MISO proposes to hold load-serving entities accountable for their share of required resources. On the other hand, MISO seems to incent investment in the “right” resources to enhance resource adequacy given the current portfolio. It appears that this can lead to serious problems. Assume a hypothetical system with 100 GW planning resource requirements based on a summer daytime peak. Suppose that some large amount of solar has been developed in the resource portfolio such that the summer daytime peak net of solar has been reduced so that there is at that time a planning resource requirement of 75 GW and that the peak net of solar has consequently moved to late evening when it is dark and solar makes no contribution to resource adequacy. Because MISO proposes to accredit solar based on its contribution in the hours when resources are tight, marginal solar would (rightly) get no capacity credit. However, if the resource adequacy obligations of load-serving entities are still based on their shares of the summer daytime peak load, the load serving entities that hold the solar that caused the summer daytime peak net of solar to be reduced to 75 MW and the peak net of solar to be in the evening will be given no capacity credit for that solar because the marginal contribution of solar is now zero. MISO must resolve this conundrum. It seems to us that MISO must either establish resource obligations and capacity credits based on the times of gross peak loads, which in the above scenario would credit solar with 25 GW capacity against a 100 GW requirement, or establish both resource obligations and capacity credit based on the hours when resources are tight, which in the above scenario would give solar no credit toward a 75 GW requirement. Using marginal contribution of solar at the hours when resources are tight while setting the load-serving entity’s requirements based on gross peaks will lead to a strong bias against solar resources and/or excessive resources and costs. We do not believe that MISO has been clear about how it will align resource requirements and capacity accreditation. We described this concern with respect to solar because the narrative is easier, but the same considerations apply to wind and other variable resources.
2. MISO is proposing to treat wind and solar resources differently than thermal resources, running a risk of undue discrimination that could drive up power system costs. In the MISO wind and solar accreditation proposal now under consideration, these resources would be accredited based on the degree that they are available at times when resources are tight. The thermal resource accreditation method already developed in Schedule 53 relies on unforced capacity found by applying year-round forced outages to these thermal resources while allowing planned maintenance to generally not count against the capacity with which thermal resources are accredited. However, tight resource hours in recent years have primarily occurred when many thermal resources were undergoing maintenance and often because many thermal resources were undergoing maintenance. Further, it has become clear that, particularly in extreme weather conditions, thermal resources have correlated (simultaneous) outages and this can lead to a resource shortage. It is imperative that MISO treat all resources in a non-discriminatory way and particularly that resources that “show up” during tight resource periods be credited for that while resources that are not available during tight resource periods should not be credited as though they did, or will, “show up”. In short, MISO should pay for performance and not potential.
3. Although MISO is currently examining these issues largely within your review of the annual resource adequacy construct, we remain open to the possibility that it would be better to focus on market design and reward the actual resources that show up during the actual resource hours through operating reserve or available reserve payments rather than through annual resource adequacy that will often resources for hypothetical availability that may not really happen.
4. It is early in the development of storage resources in MISO, so consideration of storage is not an acute issue. We note and appreciate that MISO will take up storage accreditation next year. However, we note that the accreditation of wind and solar capacity could be profoundly affected by the presence of significant amounts of storage. We encourage MISO to think through this relationship and evolve accreditation of wind and solar in a way that both properly incents the development of complementary storage and accredits wind and solar for supplying power to that storage.
Respectfully submitted,
John Liskey
General Counsel
Citizens Utility Board of Michigan
921 N. Washington Ave
Lansing, MI 48906
john.liskey@cubofmichigan.org
517-913-5105
[1] The Iowa Office of Consumer Advocate (“Iowa OCA”), the Indiana Office of Utility Consumer Counselor (“Indiana OUCC”) and the Citizens Utility Board of Wisconsin (“Wisconsin CUB”) abstain from this submission. The Minnesota Department of Commerce (“Minnesota DOC”) requests MISO better explain how this proposal was developed, how it would work, and the reasoning and data supporting it. The Minnesota DOC comment was generally supported by both the Iowa OCA and Wisconsin CUB.
MISO Environmental Sector
Wind and Solar Accreditation Comments and Questions for MISO
December 21, 2022
The Environmental Sector previously submitted comments on MISO’s non-thermal accreditation proposals on November 4, 2022, a summary of which is provided below. From reviewing MISO’s most recent publications, including its presentation at the November 30, 2022 Resource Adequacy Subcommittee or “RASC” (https://cdn.misoenergy.org/20221130%20RASC%20Item%2007b%20Non-Thermal%20Accreditation%20Presentation%20(RASC-2020-4%202019-2)627100.pdf), MISO has not yet addressed or acknowledged the main points raised in these comments, which we continue to espouse as the foundation of our concerns on MISO’s proposed new approach to non-thermal capacity accreditation. We also note that the thrust of these comments was underscored and reflected by several public comments made at the November 30, 2022 RASC meeting. Specifically, we continue to adopt the following positions:
○ The UCAP calculation looks at resources’ forced outages over the course of the entire season (historically)[2] while ELCC is focused on a discrete set of (modeled) high-risk hours as predicted by the LOL model.[3]
We appreciate that there was a robust discussion about MISO’s non-thermal accreditation proposal at the November RASC meeting, but we have a few follow-up questions, which we respectfully request that MISO answer publicly, in written form, to help stakeholders better understand the details and theoretical underpinnings of MISO’s proposals. A publicly posted Q and A document, as was used in the thermal resource accreditation process,[7] would be a useful tool as stakeholders and MISO work to design a new accreditation methodology through 2023. We also assume that these comments are the beginning of a robust stakeholder process in 2023 that will allow all stakeholders to understand the impacts of MISO’s proposed methodology, and to work together to adjust this method in appropriate ways to ensure a reasonably accurate valuing of the capacity contributions of wind and solar, and comparable treatment with thermal resources.
[image omitted]
In addition, the following figure conveys both the magnitude and duration of risk on a single graph and MISO may consider including such figures for conveying the results of the LOLE modeling. Both figures were taken from the GridPath RA Toolkit report available at gridlab.org/GridPathRAToolkit
[image omitted]
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Thank you, as always, for considering the Environmental Sector’s comments on these important topics. We look forward to continuing to work with MISO in 2023 on refining these ideas.
[1] Environmental Sector Comments of November 4, 2022 (“November Comments”) at 1.
[2] Thermal UCAP does not consider correlated outages, which can significantly impact thermal resource availability during extreme events. See Sinnott Murphy, Fallaw Sowell, Jay Apt, “A time-dependent model of generator failures and recoveries captures correlated events and quantifies temperature dependence,” Applied Energy, Volume 253, 2019, 113513, November 2019, available at https://www.sciencedirect.com/science/article/pii/S0306261919311870#f0030.
[3] Id.
[4] November Commentsat 3.
[5] November Comments at 3-4.
[6] November Comments at 4.
[7] See, e.g., https://cdn.misoenergy.org/20211006%20RASC%20Supplemental%20Q%20and%20A%20Document595123.pdf (published for the Oct. 6, 2021 RASC meeting).
[8] See, e.g.,https://cdn.misoenergy.org/RIIA%20Summary%20Report520051.pdf (Feb. 2021), at 31.
[9] See MISO’s November 10, 2022 presentation to the RASC, https://cdn.misoenergy.org/20221110%20RRA%20Workshop%20Presentation626925.pdf.
Michigan Public Power Agency (MPPA) supports the feedback of WPPI Energy.
Apex Clean Energy Comments On
RASC: Wind-Solar Accreditation Recommendation
December 21, 2022
In the November 30, 2022, meeting of the Resource Adequacy Subcommittee (RASC), MISO shared detailed recommendations for non-thermal accreditation (MISO’s Recommendation) and requested stakeholder feedback. Apex Clean Energy (Apex) appreciates the opportunity to provide comments on MISO’s Recommendation currently under discussion at the RASC.
Apex believes MISO’s Recommendation was a sudden departure from the proposal that had been under discussion for the past few months. Stakeholders had been discussing a construct using either the “average” or “marginal” ELCC method as one component, and MISO’s Recommendation to use a Direct-LOL (Loss of Load) method was unexpected.
In any event, Apex believes that MISO’s Recommendation does not provide an accreditation method for wind and solar resources that is just and reasonable.
Finally, Apex encourages MISO to consider Clean Grid Alliance’s request that MISO address its comments and questions.
Sincerely,
Fred Von Pinho
Vice-President, Transmission
Apex Clean Energy, Inc.
The Southern Renewable Energy Association (SREA) appreciates the opportunity to submit feedback on MISO’s proposed accreditation methodology for non-thermal, wind and solar resources. It’s critically important that MISO provides an accreditation methodology for wind and solar resources that properly accounts for their contributions to the MISO system in the near term, as well as future years. Echoing many other stakeholders engaged in this discussion however, we are concerned about the comparability between the accreditation methodology for Schedule 53 thermal resources and the proposed methodology for non-thermal wind and solar resources.
MISO should focus on ensuring that there is not a divergent path between developing accreditation for thermal and non thermal resource types so as to provide a clear view of how these resources perform together. Currently, the methodology used to develop UCAP for thermal resources looks at season-wide outages through the LOLE process, as opposed to the proposed methodology for wind and solar accreditation which focuses on a much smaller sample size of Direct Loss of Load (D-LOL) as an adjustment to individual unit RA hours per season to develop a class accreditation. MISO should provide a methodology that is consistent, with comparable treatment, and either develop a fleetwide ELCC across thermal and non-thermal resources, or consider the same seasonal RA hours with D-LOL adjustment approach for Schedule 53 resources as for nonthermal resources.
The approach of treating these resources separately creates silos that could create a skewed assessment of how thermal and nonthermal resources contribute to developing reserve margins, and resource adequacy throughout MISO. Developing a fleetwide average ELCC under a more aligned methodology for thermal and nonthermal resources could help put into context the reliability contributions of all resources within the MISO fleet, rather than comparing reliability contributions of different resource types, during a different sample size of both historical, and forward looking high risk hours.
Over the longer term, and in a more regional context, undervaluing investments through a non-comparable approach to accreditation for thermal versus wind or solar resource types could have adverse impacts that drive unnecessary and costly investments in thermal resource capacity. Furthermore, these investments may not actually result in greater reliability for the system. As history has shown, on February 17, 2021, up to 44 percent of installed thermal capacity in MISO South were on unplanned outage during Winter Storm Uri. Weather dependent and other correlated outages that are not captured in the Schedule 53 methodology could have an outsized impact on developing reserve margins, and possibly even at the detriment to resource adequacy into the future. Since accreditation values are inputs into LSE planning, it’s important to make sure the values are reflecting real-time challenges as much as possible at the unit level for thermal and nonthermal resources.
While it would not perfectly capture regional characteristics of wind or solar sited in areas of MISO with higher or lower resource potential and load, an average ELCC, or consideration of the same duration of RA hours with D-LOL adjustment for thermal and nonthermal resources could provide accreditation values that more closely account for their contribution to the fleetwide MISO portfolio than the current proposed method.
SREA appreciates MISO’s efforts regarding nonthermal accreditation, but wants to uplift the importance of creating a methodology which is comparable, iterative over time, and leads to least cost planning for a reliable system. The MISO fleet is rapidly shifting towards a greater amount of variable renewable energy resources, so it is crucial to have an approach that considers their contribution to system reliability and as a part of a larger portfolio of resources that have complimentary attributes. However, we cannot endorse an approach like the current proposal which appears to unfairly undermine the value of wind and solar resources to the system.
Andy Kowalczyk
Southern Renewable Energy Association
American Municipal Power (AMP) appreciates the opportunity to provide feedback on the Wind-Solar Accreditation Recommendation.
AMP supports MISO’s previous recommended proposal to accredit non-thermal generation on the basis of portfolio ELCC (class basis) and RA Hours performance (individual basis). AMP believes this approach is reasonable by accrediting non-thermal generation based on average availability during MISO peak hours to estimate their contribution toward resource adequacy and MISO has not demonstrated that this approach is flawed.
MISO lays out its view of the relative benefits of different accreditation approaches on slide 8 of the presentation (https://cdn.misoenergy.org/20221130%20RASC%20Item%2007b%20Non-Thermal%20Accreditation%20Presentation%20(RASC-2020-4%202019-2)627100.pdf).
AMP finds this comparison deficient in several respects:
Regarding slide 9 and the calculation of availability of wind and solar resources during loss of load (LOL) hours, why is this not based on actual data instead of model outputs?
Minnesota Power appreciates the opportunity to provide feedback on efforts of defining the framework for accrediting wind and solar resources. The RASC and associated workshop presentations had been focusing on the ELCC approach before the November 30, 2022 RASC meeting. At a time when stakeholders were engaging the question of average ELCC vs incremental ELCC, there was a blunt change of course at the November 30, 2022 RASC with MISO proposing the D-LOL approach. The following summarizes Minnesota Power views on wind and solar accreditation:
1. The seasonal accreditation for wind and solar should properly reflect the reliability contributions of wind and solar resources.
2. The accreditation approach for wind and solar needs to as comparable as can be reasonably pursued to thermal resource accreditation. The D-LOL approach assess the resource reliability for wind and solar using a modeling simulation periods where load is not being served due to the extreme level of system deficiency. This is not comparable with the thermal approach of evaluating performance for actual historic low margin hours.
3. The ELCC approach is proven and should be pursued in conjunction with an assessment of showing wind and solar performance during RA hours to align with the thermal resources. ELCC provides the stability to the accreditation process that reflects the capacity provided by the current portfolio, which is similar to how the thermal resource UCAP provides a measure of the capacity thermal resources are providing.
4. As a fallback position, if an incremental ELCC method is recommended, the accreditation of resources should be reflective of the incremental analysis at the time when the resource was added to the system.
There are a wide range of views across the stakeholder community, and it is important to properly reflect stakeholder input, have a recommendation that is aligned across all resources, and be a workable accreditation method that lends itself to the planning required for the system resource transformation.
Clean Grid Alliance Comments on MISO’s November 30, 2022
Proposed Accreditation Methodology for Wind and Solar
Clean Grid Alliance appreciates MISO’s work on resource adequacy and resource accreditation to ensure reliability. However, we remain concerned that MISO’s proposed accreditation method for wind and solar resources is not comparable to the accreditation of thermal resources and may be unduly discriminatory. Additionally, the initial accreditation results for wind and solar presented at the November RASC meeting show this approach would essentially eliminate the long-term capacity value for solar resources, putting a thumb on the scale for thermal generation, which is not in line with what the RRA tells us MISO member utilities and states are planning.
While MISO’s limited analysis suggests that comparing the Direct LOL approach and the current forced outage rate UCAP approaches for thermal resources results in similar numeric values using data from the 2022 RRA, this may not be the case as the generation mix changes over time. The same capacity accreditation methodology, or one that truly is comparable, should be used to accredit all resource types. MISO’s proposed Direct LOL-based accreditation methodology for wind and solar is not comparable to thermal accreditation for the following reasons:
Thermal UCAP Value (Forced Outage Based) | Proposed Wind and Solar UCAP Value (LOL-Based) |
Based on analysis of historic forced outage rates only. | Based on analysis of historic availability and synthetic data[1] together. |
Based on availability in all hours of the season including both low-risk and high-risk hours.[2] | Based on availability during a very limited number of high-risk hours of the season. This is essentially a marginal approach and does not appropriately value the capacity contribution of solar to meet peak load. |
Does not reflect correlated availability and output among fleet. Thermal availability is modeled as a fixed amount in all hours of the year or season represented by forced outage rates, not reflecting actual performance. | Reflects correlated availability and output among fleet. Wind and solar output/performance are modeled hourly and reflect diurnal and seasonal patterns of availability. |
Thermal Sum(UCAP) is the sum of all thermal resources treated together, but the LOLE report shows forced outage rates range from 4% to over 50%[3]. | Wind and solar resource Direct-LOL Based values apply to a single resource type and reflect variation between types. |
MISO has an opportunity at this point to address ongoing concerns with the Schedule 53 accreditation methodology and implement a single new accreditation methodology for all resource types in its next filing. MISO should move accreditation of all resources towards a comparable, methodology. Three options could advance the region in that direction:
First, while we do see that the direction of the LOL-based UCAP approach has value in that it is focusing more on the hours of the season when there is the greatest risk of loss of load, the LOL hours are too limited for capacity accreditation of wind and solar, especially when thermal UCAP is based on availability in all hours of the season. Using only the LOL hours could result in too small a set of hours in some seasons, or in some years, possibly even smaller than the number of RA Hours considered for individual resources. This approach also suggests that wind and solar only help to meet load in Loss of Load hours, and not during other tight margin hours, or peak load hours. MISO must include a larger set of high-risk hours to determine the UCAP value used to accredit wind and solar resources, and frankly all resource types. One way to do this would be to add to the identified LOL hours a minimum number of tight margin hours, which also represent hours when MISO has risk. A modified LOL/tight-margin hours approach should be applied to all resource types.
Second, MISO could use just the RA Hours approach without any UCAP adjustment for all resource types. This method is much less complicated to explain and provides a direct incentive for all resources to show up in the hours of highest risk. MISO should not need to use an adjustment factor for wind and solar resources, as their actual performance, reflecting diurnal and seasonal variation, is already included in the LOLE model.
Third, MISO could move all resource types to an average ELCC accreditation approach. As CGA and the Environmental Sector have stated before, average ELCC is an appropriate method to determine the fleet-wide value of existing resource types that will be available to meet load in the prompt year. We do not agree with the IMM that the PRA is the appropriate mechanism to provide a long-term incentive for future resource choice, which is under state authority. Thus, a marginal ELCC accreditation value should not be used for the PRA.
We request that MISO address the comments above and the additional questions and requests for clarification included below at the January RASC meeting or in a public Q and A document.
1. CGA’s members are also actively developing storage and hybrid resources. Please describe at the January RASC meeting, how the Direct LOL proposal to change wind and solar accreditation will interact with and impact storage and hybrid accreditation.
2. Please confirm that any curtailed MW of wind or solar will be added back into the available MW used to determine the wind or solar fleet-wide UCAP.
3. Lastly, we urge MISO to explain the details of its evaluation of how different methodologies for wind and solar accreditation meet the four criteria MISO and stakeholders agreed on - impact, feasibility, flexibility, and stability from slide 8 of the November 30th RASC meeting presentation. We request that MISO and stakeholders also include an evaluation of the Sched 53 approach for thermal resources using these same criteria. In addition, Derek Stenclik has highlighted questions that Michael Milligan has suggested to evaluate whether accreditation approaches are non-discriminatory[4]. We suggest that MISO and stakeholders also consider these questions to evaluate the various wind and solar accreditation approaches and the Schedule 53 accreditation approach for thermal resources.
Respectfully submitted,
Natalie McIntire
Technical and Policy Consultant for Clean Grid Alliance
natalie.mcintire@gmail.com
[1] It is critical that load, wind, and solar data are time-synchronized and physically consistent, but the methodologies used by Astrape to extend the wind and solar datasets from the available data record to the 1990-2019 period of the synthetic load record result in non-time synchronized data. It is unlikely that these extended datasets will appropriately identify periods of risk.
[2] We also note that the capacity accreditation method developed under Schedule 53 typically does not consider the impact of planned outages on the availability of thermal resources. However, recently MISO has experienced tight margin hours often when many thermal resources were undergoing planned maintenance.
[3] MISO’s thermal accreditation methodology distributes the sum of all thermal UCAP values to individual thermal resources based on that resource’s availability during RA Hours. MISO’s LOLE report shows that all of these resource types that are summed together for the fleet-wide thermal Sum(UCAP), yet combined cycle, combustion turbine, coal, diesel engines, etc. have quite a range of forced outage rates. https://cdn.misoenergy.org/PY%202023%202024%20LOLE%20Study%20Report626798.pdf
[4] See slide 8 – “Redefining Capacity Accreditation”, ESIG Fall Technical Workshop, Derek Stenclik, October 26, 2022, https://www.esig.energy/download/session-5-redefining-capacity-accreditation-derek-stenclik/.
Consistent with our previous comments posted November 4, 2022, WPPI supports MISO’s previous recommended proposal to accredit non-thermal generation based on portfolio average ELCC (Class basis) and RA Hours performance (Individual basis). WPPI believes this approach is reasonable and agrees with the statement regularly included in previous Wind & Solar Capacity Reports, that "ELCC is the preferred methodology for determining the capacity value of wind." We don't believe MISO has demonstrated that this approach has flaws that merit its abandonment.
MISO lays out its view of the relative benefits of different accreditation approaches on slide 8 of the presentation (https://cdn.misoenergy.org/20221130%20RASC%20Item%2007b%20Non-Thermal%20Accreditation%20Presentation%20(RASC-2020-4%202019-2)627100.pdf). WPPI finds this comparison deficient in several respects:
Invenergy appreciates the opportunity to submit comments regarding MISO’s most recent Non-Thermal Accreditation methodology proposal.
Invenergy does not support the Direct Loss-of-Load accreditation proposal. Though there are many technical concerns, Invenergy would like to offer two suggestions for MISO’s high-level approach.
1. Establishing a broadly supported definition of “comparability” is essential for a meaningful stakeholder discussion.
“Comparability” has become analogous to “non-discriminatory” and has been a focus of IPP and Environmental sector feedback for nearly a year. MISO staff has acknowledged the importance of “comparability” and has included literature and analysis in stakeholder presentations since the May RASC.
If the goal of “comparability” is to run the thermal units through a non-thermal analysis and get a similar result to the thermal accreditation, then MISO’s analyses to date have confirmed this definition.
However, if Invenergy believes a “comparable” method means that non-thermal and thermal resources are being evaluated during the same pool of hours with an equitable measuring stick, then the proposed accreditation does not meet this criterion. Meaningful discussion requires a common language.
Invenergy supports CGA’s proposal of “comparability criteria” and asks MISO staff to consider allocating discussion time on the topic at the next RASC.
2. The proposed accreditation must be aligned with the System Attributes discussion, as the current contradictions signal that major market changes are being made in siloes.
The new Direct Loss-of-Load proposal accredits non-thermal resources based on their marginal contribution to reliability during a narrow set of high-risk hours, which will have tremendous downward pressure on accreditation as compared to the Schedule 53 methodology.
However, MISO staff has been raising alarms to the Board and to external stakeholders about the coming “Gap” between ICAP and Accredited Capacity (June Board Presentation, November RRA Workshop). The proposed methodology would only exacerbate this problem.
MISO recently kicked off a System Attributes discussion, in which the Hypothesis proposes evolving the “Capacity” attribute into “Availability” (September Board Meeting). But the proposed methodology only measures availability during a narrow set of hours.
These perceived contradictions are concerning because when major elements are built in siloes, the system becomes strained and fragile once it needs to stand on its own.
Invenergy would recommend that MISO discuss how this proposal aligns with the System Attributes hypothesis, or perhaps allow that high-level market framing discussion to mature before proceeding.
Xcel Energy appreciates the opportunity to provide feedback regarding the Direct-LOL approach to determine class level wind and solar capacity accreditation, as presented during the November 30, 2022, RASC. LOL hours favor the very peak hours so this method would accredit wind and solar resource based only on a few hours where the modeled generation supply is inadequate to serve the modeled load. This is not in alignment with the PRM which is calculated across all hours. We consider the Direct-LOL methodology to be a marginal accreditation approach. Therefore, unless the PRMR is revised with the same implementation date to calculate the requirement based on the net peak load (as opposed to the gross peak load), we are not supportive of the Direct-LOL approach. If MISO moved forward with the Direct-LOL approach and the PRMR based on the net peak load, then revising the capacity accreditation of Schedule 53 resources should be reduced to only the RA hours. This would create alignment across the load obligation requirements and the capacity accreditation methods.
The issue, of course, is that forecasting the net peak load is not as easy as forecasting the gross peak load, so moving to a PRMR based on net peak load creates uncertainty in the load obligation calculation. Therefore, we recommend maintaining the calculation of the PRMR based on the gross peak load and using the average ELCC methodology to calculate the wind and solar class level accreditation values. This would bring ensure that all resource types are treated in a similar fashion and the load obligation is in alignment.
We strongly support an average ELCC approach to calculate the class level wind and solar accreditation values and allocation to the individual resources based on RA hours. We encourage MISO to compare this approach to their current proposal and provide the details regarding the benefits of each. We understand that the Direct-LOL approach is less computationally effective, but MISO has been running an average ELCC study for wind resources for over 13 years now, so we don't believe that the computational efficiency is a limitation. In addition, we note that the recently released RRA report incorporated an average ELCC approach for wind, solar, hybrids and stand-alone batteries for 2031 and 2041. If the average ELCC is computationally intensive and not easily extendable to other resource types, why was it used for the RRA study to demonstrate the capacity value of renewable and storage resources at high levels of penetration? Dismissing the "feasibility" differences in the benefits shown on slide 8, the only difference then becomes "flexibility". We ask MISO to demonstrate the differences in accounting for synergistic effects and why that becomes the critical factor to propose the Direct-LOL approach over the average ELCC approach.
WEC Energy Group does not support MISO’s proposal to accredit wind and solar resources with their average availability during Loss of Load Hours (LOL Hours) from the LOLE study. We continue to support the use of a Schedule 53 approach to accredit all resources. MISO and stakeholders expended significant time and effort developing the Schedule 53 definition of hours when resources are most needed and we should leverage that work when accrediting all resources.
MISO’s proposal to accredit wind and solar resources with their average availability during LOL Hours is inconsistent with the resource accreditation problem statement, which states, “Resource accreditation should reflect the availability of resources when they are most needed.” Schedule 53, approved by the FERC, already defines when resources are most needed – those are Tier 2 or RA Hours. RA Hours include hours during Maximum Generation Emergency declarations and the hours when the operating margin, a measure of available supply capacity above demand and reserve requirements, is at its lowest. LOL Hours represent those hours from the LOLE model where loss of load accumulates, which occurs when load is greater than the available generation (a firm load shed scenario). By definition, LOL Hours are only a small subset of RA Hours. Accrediting wind and solar resources based on their modeled performance during LOL Hours is unduly discriminatory when compared to the accreditation of non-intermittent resources. Wind and solar resources are entitled to provide capacity value when they are most needed, which is during RA Hours, and should not have their accreditation limited by their availability only during a simulated firm load shed scenario.
The LOLE model demonstrates the ineffectiveness of LOL Hours to determine when resources are most needed when considered with the Schedule 53 definition of RA Hours. The LOLE model uses several weather years and several probabilistic samples within each weather year when computing different measures of resource adequacy. Some of those weather years and samples will have periods within each season with zero LOL Hours. This means the availability of wind and solar resources is not valued in those samples. However, RA Hours will accumulate during actual operating conditions when there is no loss of load but when wind and solar are providing value. As demonstrated within the November 30 presentation materials, the Direct LOL approach shows near 0% solar capacity value at higher penetrations. However, if that solar is removed from the LOLE model, we expect an increase in the LOLE, demonstrating that solar on the MISO system is providing capacity value that is not captured by the Direct LOL approach.
Regarding the concern raised in past RASC meetings that the UCAP/ISAC ratio presents a challenge for wind and solar resources, we do not believe a UCAP/ISAC ratio is needed for wind and solar resources. Unlike thermal resources that are modeled within the LOLE study at an ICAP with a forced outage rate, wind and solar resources are modeled with an hourly energy profile, representing their expected availability during Tier 1 and Tier 2 hours. The resulting Planning Reserve Margin already accounts for the expected availability of wind and solar resources – no adjustment to their ISAC value is needed (or alternatively, the UCAP/ISAC ratio for wind and solar is 1.0). As noted in testimony accompanying MISO’s seasonal resource adequacy proposal, a conversion ratio is needed for thermal resources to ensure alignment with the Planning Reserve Margin from the LOLE model because thermal resources are not modeled based on their performance during Tier 1 and Tier 2 hours. Rather, thermal resources are modeled at their ICAP and an associated forced outage rate, which MISO has demonstrated does not capture their availability when they are most needed. Since the LOLE model and resulting Planning Reserve Margin already reflects the hourly output profiles for wind and solar resources during Tier 1 and Tier 2 hours, no adjustment ratio is needed for wind and solar.
Feedback by Public Service Commission of Wisconsin (PSCW) Office of Regional Markets (ORM) Staff to Midcontinent Independent System Operator (MISO) on Accreditation Reforms for Non-thermal Resources:
Direct-Loss of Load (D-LOL) implementation at Class Level
The PSCW ORM staff recognizes that the new accreditation approach proposed for non-thermal resources at the class level attempts to simplify the methodology previously proposed in the ELCC.
At a high level, PSCW ORM staff is concerned with the D-LOL proposal absent substantially more stakeholder development and explanation. The proposal significantly devalues solar accreditation by the time only 37 gigawatts of solar is developed in MISO, whereas MISO’s current summer peak load is nearly 120 gigawatts.
The PSCW ORM staff would like for the new accreditation methods for thermal and non-thermal resources to value the resource adequacy (RA) contribution of each fairly and reasonably based on actual capability, but also to make sure RA approaches are not inappropriately de-valuing the contributions of resources prematurely. For example, as stated above, with a MISO peak summertime load of 120 GW, why would solar’s capacity value plummet to 5% by the time only 37 GW are developed? This does not make intuitive sense.
To better understand the proposed D-LOL method, ORM staff is asking MISO to provide more detailed step-by-step examples on how the accreditation will vary per resource type into the future. While studying the already shown steps within the new proposed method, ORM ran into the following questions:
During the RASC meeting, MISO highlighted that within the next year they will continue to work on the proposed D-LOL method and file with FERC during the second half of 2023. We are asking for MISO to provide a more detailed timeline of the actual implementation of the new accreditation method for non-thermal resources. It would be helpful if MISO could provide a more detailed date as to when it is expected for this new accreditation method to come into effect under the seasonal construct.
MISO-wide vs. regional
PSCW ORM Staff asks for MISO to continue to have greater geographical granularity in the implementation of the accreditation reforms.
Workshops
A span of almost 3 months was dedicated to the specific implementation of an ELCC-based method, whereas thus far only a few weeks have been given to provide feedback on the D-LOL method. Sufficient time must be given to stakeholders so we can understand the steps in greater detail. We suggest for MISO to provide at least one workshop and additional feedback window before the half of 2023, and potentially two of each before the official filing to FERC.
Vistra Corp. (“Vistra”) appreciates MISO providing stakeholders with the opportunity to submit feedback on the most recent wind and solar accreditation proposal. Vistra looks forward to additional discussions and workshops on this topic, which we believe will be critical for providing stakeholders with clarity on MISO’s recommended class level accreditation approach of ‘Direct-LOL’ for wind and solar resources. Vistra, like other stakeholders, is trying to better understand why MISO is now shifting to a Direct-LOL methodology which represents a significant change from the Portfolio level ELCC approach that had been discussed during stakeholder meetings and workshops for the past several months. The Direct-LOL class level approach is a novel methodology, while the Portfolio level ELCC has been endorsed by FERC in recent orders approving the capacity accreditation methodology of resources, including wind and solar resources, in both NYISO[1] and PJM.[2]
Throughout these non-thermal accreditation discussions, MISO has emphasized that the overarching focus of the wind and solar accreditation process would be on retaining key design elements of the Schedule 53 thermal accreditation process and extending those same concepts to wind and solar resources, unless there is an overwhelming reason not to do so. With the new Direct-LOL approach for class level accreditation, MISO appears to have essentially abandoned one of the most important design elements of Schedule 53: the principal of selecting the tightest group of hours (3% or 65 tightest margin hours in the case of thermal) in a season to determine a resource’s availability. This is a critical component because as MISO has pointed out, including more performance hours better accounts for infrequent risks such as extreme weather without penalizing individual resources. Based on the information presented at the November RASC meeting, it appears the Direct-LOL simulation would evaluate a much smaller number of hours to determine a resource’s availability and performance. MISO has also not explained why it would not base thermal portfolio UCAP values on a Direct-LOL approach if it believes this approach is appropriate for non-thermal resources. Additionally, during the November RASC meeting, MISO failed to provide stakeholders with any information explaining why MISO believes it’s necessary to pivot from the FERC endorsed ELCC methodology to this new Direct-LOL approach. Vistra asks that MISO provide stakeholders with information on the accreditation deficiencies of the previously proposed ELCC methodology, both for marginal and average ELCC.
To clarify Vistra’s position- MISO has not provided stakeholders with enough information or data for Vistra to either support or oppose any of the wind and solar class level accreditation proposals that have been introduced in the stakeholder process; instead, Vistra is simply trying to understand why after months of workshops and discussions, MISO believes the Schedule 53 concepts and ELCC class level accreditation methodology are no longer effective for calculating class level wind and solar resources, despite their approval from FERC and use in other RTOs. Finally, Vistra requests that MISO provide additional data so that stakeholders can properly analyze the impact the proposed Direct-LOL approach will have on wind and solar. For example- under Direct-LOL, MISO proposes calculating the availability of wind and solar resources during a limited number of simulated LOL hours. Beyond a link to a high-level presentation made at the Energy Systems Integration Group, little information was provided on how MISO’s model will select the simulated LOL hours. Vistra and other stakeholders should be provided access to the data and model that will simulate the Direct-LOL calculations so we can better understand the impact to our individual resources.
The Entergy Operating Companies ("EOCs")[1] appreciate the opportunity to provide feedback on MISO’s proposed solar/wind accreditation reforms. MISO’s determination regarding this issue may have a significant impact on member utilities as they pursue renewable resource development that is key to achieving their and their customers’ goals; the EOCs therefore encourage MISO to give careful consideration to the feedback of its stakeholders in making that determination.
MISO’s Proposed Direct LOL-Methodology
The EOCs do not support MISO’s Direct-LOL methodology proposal. This Direct-LOL methodology will produce a very similar result to a Marginal ELCC proposal, and for this reason, the EOCs have the same concerns with MISO’s Direct-LOL methodology as we do with the Marginal ELCC methodology. Please see our previously submitted feedback to understand our concerns with Marginal ELCC. The EOCs continue to believe that an Average ELCC approach is the correct methodology to use for determining the fleetwide accreditation of wind/solar resources in the prompt year PRA.
The Direct LOL-Methodology is well suited for measuring the reliability value that the next wind/solar resource will provide to the MISO system, but it does a poor job of measuring the cumulative reliability value of the existing wind/solar fleet on MISO’s current system, which the EOCs believe is the primary purpose of accreditation in MISO’s prompt year PRA. To illustrate this point, in a future high solar penetration system the Direct-LOL methodology will provide a near zero capacity credit to the entire MISO solar fleet. This would seem to indicate that the solar fleet is providing a near-zero reliability contribution to the MISO system. However, if we were to remove the entire solar fleet from this hypothetical MISO system, there would certainly be a large increase in loss of load events, demonstrating that the presence of the solar on the MISO system is contributing towards reliability to a much greater extent than is represented by the Direct LOL-Methodology near-zero value. An Average ELCC methodology, on the other hand, would accurately capture the reliability contribution of the entire wind/solar fleet to the MISO system. A methodology that does not provide reasonable capacity credit to an entire class of resources commensurate with their contribution to system reliability cannot be just and reasonable.
The Direct LOL-Methodology is not equivalent to the thermal SAC methodology and results in unequal treatment between wind/solar resources and thermal resources. Under SAC, the total amount of accredited capacity is scaled up to equal thermal UCAP on a MISO-wide basis. MISO’s FERC SAC filing explains that this scaling step is performed “to avoid undesirable impacts to PRA requirements and non-schedule 53 resources.” The Direct LOL-Methodology creates concerns similar to those explained in MISO’s FERC SAC filling, but unlike the SAC methodology, these concerns are not addressed by scaling up the new solar/wind accreditation methodology capacity to equal the solar/wind capacity on a UCAP basis. As a result, per MISO’s own reasoning as set forth in its recent FERC filing, the Direct LOL-Methodology (1) has undesirable impacts to the PRA requirements, (2) significantly alters the relative share of accreditation between thermal resources and wind/solar resources, and (3) unfairly reduces the amount of revenue that solar/wind resources will receive in the PRA. For these reasons, the EOCs believe that the Direct LOL-Methodology has serious shortcomings.
Entergy Proposal
If MISO is not willing to adopt the EOCs’ preferred method of an Average ELCC methodology for accrediting wind/solar resources, the EOCs propose as a compromise position that MISO adopt a blended Average ELCC and Marginal ELCC approach, where MISO would calculate the Average ELCC and the Marginal ELCC separately and then average the two methodologies together to produce a final result. The hybrid approach would seek to balance the competing interests of (1) sending a proper signal regarding what types of new capacity are needed within the market and (2) providing credit to existing resources that is commensurate with their true contribution to system reliability.
[1] The Entergy Operating Companies are Entergy Arkansas, LLC, Entergy Louisiana, LLC, Entergy Mississippi, LLC, Entergy New Orleans, LLC, and Entergy Texas, Inc.
MISO needs to consider forced outage rates of wind and solar resources just like it does for conventional resources.
MISO needs to consider the effects of calm, cloudy days.
MISO need to consider the effects of wind droughts such as January 28-30, 2020 and low wind during Winter Storm Uri in February 2021. Since intermittent resource outputs are often highly correlated, MISO should consider given more weight to extremes rather than just using averages.
MISO should consider the effects of snow-covered solar panels. Snow cover could exist for days or even weeks in northern MISO.
MISO should consider locational sunrise and sunset times and assigned solar capacity value based on location and season.
MISO should consider the negative load effects of distributed solar which changes the load curve pushing the peak to later in the day when solar has less capacity value..