1.
Please provide a summary of your organization’s general comments on the meeting regarding alternative proposals.
The Public Advocates Office at the California Public Utilities Commission (Cal Advocates) appreciates the opportunity to comment on the California Independent System Operator’s (CAISO) August 19, 2024 storage bid cost recovery (BCR) and default energy bids enhancements workshop. As the state-appointed independent ratepayer advocate at the California Public Utilities Commission (CPUC), our goal is to ensure that California ratepayers have affordable, safe, and reliable utility services while advancing the state’s environmental goals. In this initiative, Cal Advocates seeks to protect ratepayers from the costs of unwarranted BCR and to ensure that storage resources are properly incentivized to deliver CAISO market awards in a manner that will most efficiently and effectively maintain system reliability.
Cal Advocates supports the position of the CAISO’s Department of Market Monitoring (DMM) that Track 1 of the initiative must simultaneously address each of the risks (opportunities for market gaming, market inefficiencies, and diminished reliability) that the current BCR rules create.[1]
The CAISO’s proposal (CAISO proposal) to reclassify energy associated with state-of-charge (SOC) constraints during the real-time (RT) binding interval as non-optimal, and thus ineligible for BCR,[2] addresses all three risks. The CAISO proposal is the most effective and viable option to address the need to protect ratepayers from the high costs and risks that the current BCR rules create.[3] In contrast, the alternative proposals from the California Energy Storage Alliance (CESA) [4] and Vistra Corp. (Vistra)[5] fail to simultaneously mitigate the risks identified by DMM.
Cal Advocates recognizes that there are broader issues with the overall BCR construct, as applied to energy storage resources, that the CAISO and stakeholders should address in the ongoing initiative. For example, the CAISO explains that BCR was originally designed for thermal units to allow for the recovery of unit commitment and minimum load costs.[6] Energy storage resources lack these conventional drivers for BCR.[7] Moreover, thermal units are ineligible for BCR payments when unable to fulfill day-ahead (DA) schedules due to unavailability, while energy storage resources are eligible for BCR when unable to fulfill DA schedules due to insufficient SOC.[8] This leads to materially different treatment of storage resources that may warrant a technology-specific BCR design.
However, the longer-term need to fundamentally address how and under what specific circumstances modified BCR rules should or should not be applied to storage resources should not delay the implementation of the CAISO proposal that is immediately necessary to protect ratepayers from unwarranted costs and system outages. Adoption of the CAISO’s proposed policy changes on an interim basis would be acceptable if the CAISO includes broader reform of BCR rules for energy storage in the scope of a subsequent track of the initiative.
[1] CAISO DMM, Comments on Storage Bid Cost Recovery and Default Energy Bids, Issue Paper and Straw Proposal for Track 1, August 8, 2024 at 1. Available at: https://www.caiso.com/documents/dmm-comments-on-storage-bid-cost-recovery-and-default-energy-bids-straw-proposal-aug-8-2024.pdf.
[2] CAISO, Storage Bid Cost Recovery and Default Energy Bids Enhancement Issue Paper and Straw Proposal for Track 1, July 26, 2024 (IPSP) at 25. Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Issue-Paper-and-Straw-Proposal-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Jul-26-2024.pdf.
[3] IPSP at 9, 16, and 18.
[4] CAISO, Storage Bid Cost Recovery and Default Energy Bid Enhancements, August 19, 2024 (August 19 Workshop) at 17-24. Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Aug-19-2024.pdf.
[5] August 19 Workshop at 25-26.
[6] IPSP at 8.
[7] IPSP at 9.
[8] IPSP at 9.
3.
Please provide your organization’s comments regarding the alternative proposals put forth by stakeholders, the outstanding questions regarding their implementation, and how they compare relative to the status quo and the Proposed Solution.
Under the status quo, energy storage resources receive RT BCR payments when they are unable to fulfill DA schedules due to insufficient SOC.[1] The BCR payment is calculated as the difference between RT dispatch and the DA schedule times the difference between the RT bid and RT locational marginal price (LMP): (RT dispatch – DA schedule) * (RT bid – RT LMP).[2] Negative values are payments to the storage resource resulting from its inability to meet the DA schedule.
The CAISO proposes to make storage resources ineligible for BCR if the resource’s SOC is at its maximum or minimum value at the start of the binding 5-minute RT interval.[3] The CAISO’s proposed solution addresses two concerns: 1) storage resources are not exposed to RT prices for deviating from DA schedules, and 2) storage assets are incentivized to bid strategically to maximize the combined BCR and market payment.[4] Storage resources are not exposed to RT prices because they are fully compensated for failing to meet their DA schedule. A storage resource can maximize BCR payments by dropping its RT bid to the bid floor in anticipation of a failure to meet DA schedules.
CESA proposes to maintain energy storage’s eligibility for BCR payments when it is unable to fulfill its DA schedules due to insufficient SOC.[5] Instead, CESA proposes to change the formula that calculates the BCR payments for storage. CESA would modify the BCR payment formula by replacing the RT bid with the DA LMP from the corresponding hour: (RT dispatch – DA schedule) * (DA LMP – RT LMP). CESA asserts that this change would eliminate the opportunity for market gaming, since the CAISO would no longer take the resource’s bid into consideration.[6]
However, CESA’s proposed solution fails to resolve the CAISO’s Concern 1. Storage would remain insulated from RT prices because BCR payments protect non-performing resources from having to buy-back unfulfilled DA schedules at potentially high RT prices. Instead, those high real-time buy-back costs are passed on to other market participants and to ratepayers. As the CAISO has observed, RT prices remain significantly higher than DA prices for a significant portion of the day under stressed grid conditions.[7] CESA’s proposal would continue to compensate storage at the potentially high differential between DA and RT prices. Moreover, RT prices under stressed grid conditions may increase further due to the elimination of the soft-offer cap for storage, which will increase ratepayer’s exposure and continue to shield storage resources.
Another weakness in CESA’s proposal, as noted by the CAISO, is that it is unclear how the CAISO can implement the DA LMP for storage resources in the Western Energy Imbalance Market (WEIM).[8] WEIM storage resources do not have a DAM LMP to reference because they do not participate in the DA market.[9] About 3,500 mega-watts (MW) of battery resources participate in WEIM as of June 2024, compared with 11,200 MW of storage in the CAISO balancing area.[10] RT BCR payments to WEIM resources in the 4th Quarter of 2023 accounted for approximately 20% of total RT BCR payments, or $7 million, of which approximately 10% are paid to batteries,[11] which amounts to several million dollars per year. Under CESA’s proposal, RT BCR payments to WEIM will only grow as more storage resources are added in the WEIM footprint. Without a DAM LMP to reference, CESA’s proposal will result in inconsistent treatment of resources inside and out of the CAISO Balancing Area (BA). The inability to apply the same solution to all battery resources participating in the RT market should disqualify the CESA proposal from consideration.
Like CESA, Vistra would retain energy storage’s eligibility for BCR when unable to meet DA schedules due to insufficient SOC, and thus would also keep energy storage shielded from RT prices. Also like CESA, Vistra proposes to modify the BCR payment formula, but instead of using the DA LMP, Vistra would modify the BCR formula by replacing the RT bid with the storage resource’s Default Energy Bid (DEB).[12] The storage DEB is a single value produced in the DA market run for all hours based upon a storage resource’s energy costs, variable operations costs, and opportunity costs.[13] The opportunity cost component is determined by the 4th highest LMP in the DA market run.[14]
Application of the DEB would be no more effective in mitigating unwarranted BCR than would the DA LMP. As with the DM LMP, the CAISO finds that DEBs are lower than RT prices under stressed grid conditions.[15] Recent CAISO analysis of a set of high priced days between 2022 and 2024 indicates that the DEB does not regularly rise above $1,000/MWh during conditions when RT prices rise above $1,000/MWh.[16] As in CESA’s proposal, large differentials between RT prices and the single DA storage DEB would expose ratepayers to large BCR payments and shield storage resources from the same high RT prices. Vistra’s proposal to use the DEB in the BCR formula poses the same risks to ratepayers as CESA’s proposal to the DA LMP.
Vistra further proposes to classify RT energy as non-optimal, and thus ineligible for BCR, in the intervals in which the storage resources submit outage cards or bid parameters that reduce the resource’s minimum or maximum capacity or the maximum of minimum continuous storage energy.[17] Vistra argues that this narrower limitation on BCR eligibility is less punitive.[18]
However, in comments on the CAISO 2024 Policy Roadmap, Vistra noted that there is no CAISO tariff outage reporting requirement for standalone, co-located, or hybrid storage resources.[19] In that context, Vistra argued that the outage reporting gap for storage resources poses reliability risks, and that the same outage reporting requirements that apply for other generation resources should also apply to storage resources.[20] However, Vistra’s proposal in this initiative would perversely incentivize storage resources to not submit outage cards in order to remain eligible for BCR payments. As Vistra argued in its Policy Roadmap comments, this would adversely affect CAISO system reliability. Vistra’s proposal in this initiative would impose additional negative impacts on CAISO system reliability. At the very minimum, the CAISO should not consider Vistra’s proposal to classify RT energy as non-optimal until the gap in energy storage outage reporting is closed.
Setting aside the problems with each alternative proposal, both proposals are designed to retain some amount of BCR for battery operators. But the DMM aptly describes these as “situations where batteries may receive inappropriate or inefficient bid cost recovery payments.”[21] Storage owners engaged in intertemporal energy price arbitrage should not be exempt from the same risks faced by any market participant. Cal Advocates recommends that the CAISO adopt its own proposal, not the alternative proposals.
[1] CAISO, Storage Bid Cost Recovery (BCR) and Default Energy Bid (DEB) Enhancements, Stakeholder Meeting on Issue Paper and Straw Proposal, August 5, 2024 (August 5 Workshop) at 20. Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Aug-5-2024.pdf.
[2] August 5 Workshop at 16.
[3] August 5 Workshop at 25.
[4] August 19 Workshop at 7.
[5] August 19 Workshop at 17.
[6] August 19 Workshop at 18.
[7] CAISO, Energy Storage and Distributed Resource Phase 4 Final Proposal, August 21, 2020 (ESDER 4 Final Proposal) at 30-31. Available at: https://stakeholdercenter.caiso.com/StakeholderInitiatives/Energy-storage-and-distributed-energy-resources; and Rule for Bidding Above the Soft Offer Cap Final Proposal, May 17, 2024 (Soft Offer Cap Final Proposal) at 16. Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Final-Proposal-Price-Formation-Enhancements-May17-2024.pdf.
[8] August 19 Workshop at 21.
[9] August 19 Workshop at 21.
[10] DMM, 2023 Special Report on Battery Storage, July 16, 2024 (DMM 2023 Storage Report) at 4. Available at: https://www.caiso.com/documents/2023-special-report-on-battery-storage-jul-16-2024.pdf.
[11] DMM, Q4 2023 Report on Market Issues and Performance, April 24, 2024 at 56. Available at: https://www.caiso.com/documents/2023-fourth-quarter-report-on-market-issues-and-performance-apr-24-2024.pdf.
[12] April 19 Workshop at 25.
[13] ESDER 4 Final Proposal at 22.
[14] ESDER 4 Final Proposal at 26.
[15] ESDER 4 Final Proposal at 30-31. The CAISO examined stressed conditions in August and February of 2019, and showed that in August there were 2.7 hours where RT prices exceed the DEB, with RT prices upwards of $1,000/MWh. At that time the energy storage soft offer cap bid cap of $1,000/MWh was in effect. Similarly, in February 2019 there were 5.3 hours when RT prices exceeded the DEB, during which prices also reached $1,000/MWh. As of August 1, 2024, the soft-offer cap was eliminated, and storage can bid up to $2,000/MWh during stressed grid conditions.
[16] Soft Offer Cap Final Proposal at 16. With the elimination of the soft offer bid cap in the RT market, RT prices can reach up to $2,000/MWh.
[17] August 19 Workshop at 17-18.
[18] Vistra, Comments on the Storage Bid Cost Recovery and Default Energy Bids Enhancements Issue Paper and Straw Proposal, August 8, 2024, response to Question 1. Available at: https://stakeholdercenter.caiso.com/StakeholderInitiatives/storage-bid-cost-recovery-and-default-energy-bids-enhancements.
[19] Vistra, CAISO 2024 Policy Roadmap Storage Outage Improvements, May 15, 2024 (Vistra Roadmap Comments) at 4. Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/VistraCorp-Storage-Outage-Management-Improvements-May-15-2024.pdf.
[20] Vistra Roadmap Comments at 2.
[21] DMM, Comments on Price Formation Enhancements: Rules for Bidding above the Soft Offer Cap Draft Final Proposal, May 8, 2024 at 3. Available at: https://stakeholdercenter.caiso.com/Common/DownloadFile/4b4c5dd5-61f3-4a39-81e1-f7f44b90055e.