Please provide any redline changes and embedded comments your organization may have on the Subscriber Participating Transmission Owner Model revised draft tariff language as an attachment to this comment template, and provide any additional comments in the text box below.
Pattern Energy appreciates the opportunity to comment on the latest revised draft tariff language for the Subscriber Participating Transmission Owner (SPTO) model policy. Pattern Energy supports the SPTO model policy and is generally supportive of the draft tariff language. However, we still have several questions related to how Maximum Import Capability (MIC) and Transmission Planning Deliverability (TPD) will be treated, the relationship between the two, and the timing of switching from MIC to TPD as part of the transition from being an importing generator to joining the CAISO BAA (through the SPTO model).
Section 8.9.1 (b): Pattern Energy supports the inclusion of MIC associated with non-contiguous portions of the CAISO BAA and SPTO Subscriber Rights under “prior commitments.” However, we note that the current draft focuses only on MIC made available by Load Serving Entities, which is more narrow than current tariff provisions governing access to MIC. Section 188.8.131.52.1 (Step 13) of the CAISO Tariff also allows for “Participating Generators,” and “System Resources to request “unassigned Available Import Capability on a specific Intertie on a per MW basis.”
Assuming it was not the CAISO’s intent to narrow access to MIC in this way under the SPTO model, Pattern Energy suggests modifying the SPTO tariff language Section 8.9.1 (b) to also include MIC made available to Participating Generators and System Resources. Pattern Energy is not proposing a specific redline at this point, as there are multiple ways to effectuate this change—some more efficient than others—but we would be happy to work with the CAISO to craft an amendment, if that would be helpful.
If the CAISO’s intent was to limit the applicability of Section 8.9.1 (b) to only MIC made available by Load Serving Entities, without further information, Pattern Energy opposes such a limitation and requests more information on why this would be appropriate under the SPTO model.
With respect to MIC calculatoins and access more generally, Pattern Energy appreciated that the Final Proposal for the SPTO Model explains that the ISO will calculate MIC capability at new ISO BAA boundary points the same as all other interties, however neither the Final Proposal nor the draft tariff language provide detail about how the new MIC and/or TPD calculations and procedures will work for non-contiguous portions of the CAISO BAA, which will inherently be more complicated. It is also unclear whether generators in a non-contiguous portion of the CAISO BAA would have access to MIC at a new intertie point when it is formed, or if deliverability would be offered instead, and-- if so-- when. Without a better understanding of the timing and access to MIC and TPD under the SPTO model it is difficult to say if the draft tariff language is sufficiently permissive and equitable for all use-cases or not.
Having more information around the treatment, access, and timing of MIC and TPD for non-contiguous SPTOs and their subscribers will ultimately be critical in order to assess the costs, benefits, and timing of utilizing SPTO model or not.
Given these outstanding questions, Pattern Energy would appreciate if the CAISO continue the tariff commenting process with stakeholders until a more full understanding of the questoins above is achieved and we can be certain that the final tariff proposal fully accommodates all SPTO use-cases.