On July 29, 2026, the NYISO posted the list of scenarios it will analyze in the 2026 Reliability Needs Assessment (RNA) and reviewed that list with stakeholders at the August 3 TPAS/ESPWG meeting. Five scenarios were selected, along with ten additional informational scenarios and sensitivities that will be run as time permits.

For the 2026 RNA, all scenario analyses and results are informational. That distinction matters, because the NYISO is separately developing Reliability Planning Process reforms that would create a scenario planning framework capable of declaring actionable needs based on scenarios. The scenario work in this RNA is intended in part to inform those reforms.

Here is what was selected and what it means for market participants.

The Base Case Reference Points

Each scenario is defined by how it varies from the 2026 RNA Base Case. The Base Case assumptions are as follows:

  • 2026 Gold Book baseline demand, with a summer coincident peak of 30,713 MW in 2036 before large loads
  • Large load demand of 2,717 MW in 2036
  • The Moderate Aging Model, with 2,585 MW of nameplate generation considered at risk in 2036
  • 6,300 MW of planned queue projects under the RNA Base Case inclusion rules
  • Net imports to the NYCA of 2,920 MW in a 2036 summer peak condition
  • Emergency assistance of 3,500 MW declining by 100 MW per planning year

The Five Selected Scenarios

Scenario A tests policy achievement and economic growth. It applies the 2026 Gold Book higher demand forecast, raising the 2036 coincident peak to 32,607 MW before large loads, while holding large loads at the baseline level on the reasoning that large load materialization is not tied to policy advancement. It also applies the Increased Aging Model (3,036 MW at risk in 2036) and expands planned project inclusion to all cost-allocated projects, or 10,900 MW. Following stakeholder feedback that 2036 was too soon to assume new nuclear generation, the 1 GW nuclear assumption was removed from this scenario and moved to an informational sensitivity.

Scenario B tests accelerated large load development. Large loads rise to 4,113 MW in 2036 under the higher demand forecast. The NYISO notes this does not represent the roughly 14 GW of large loads in the interconnection queue, but a reasonable acceleration over the Base Case. Aging generation is reduced to 1,213 MW at risk on the reasoning that added demand would keep more existing generation online. Emergency assistance from adjacent regions drops to 2,000 MW in all planning years and net imports fall to 1,460 MW, both reflecting large load growth in neighboring systems.

Scenario C tests supply chain constraints and slower growth. Demand falls to the lower forecast (28,719 MW coincident peak in 2036), large loads fall to 1,211 MW, and 850 MW of planned projects are delayed an additional one to five years.

Scenario H tests inverter-based resource performance. Planned project inclusion expands to the 10,900 MW cost-allocated set, but planned IBR reactive capability is reduced to a 0.95 power factor that decreases at lower dispatch, reflecting the minimum obligation under a typical interconnection agreement rather than voluntary reactive contribution. The scenario also models a south-to-north exchange with PJM imports of 965 MW and a 1,100 MW export to Hydro-Québec, along with higher land-based wind output in night-time light load conditions. Its transmission security analysis is run at night-time light load.

Scenario J aligns with the System and Resource Outlook contract case. Planned project inclusion rises to 7,000 MW, capturing any project holding a Tier-1 REC or OREC contract from NYSERDA regardless of progress on other milestones, and adds non-firm Phase 1 and Phase 2 local transmission projects to the extent modeling data allows.

Which Analyses Run Where

Not every scenario gets every analysis. Transmission security is run for Scenarios B and H. Transmission security margin and resource adequacy are both run for Scenarios A, B, C, and J.

The Informational Scenarios

Ten additional scenarios and sensitivities will be performed as time allows, several of which are diagnostic rather than predictive. Status Quo assumes no planned projects go forward, testing how dependent reliability outcomes are on the planned project set. No Aging Generation isolates how much of any identified need is attributable to aging generation risk. No Planned Large Loads does the same for large loads. Flexible Large Loads and Demand Side Flexibility test whether flexibility or demand response could alleviate needs. The remaining items are Copper Sheet, Loss of All Imports, Chateaugay/CHPE Limits, No Voltage Limited Interfaces, and the 1 GW Nuclear Generation sensitivity on Scenario A.

What Stakeholders Changed

Three of the NYISO’s responses to comments are notable. The 1 GW nuclear assumption came out of Scenario A and became a sensitivity. The higher range assumption for imports from neighboring systems was not carried into any selected scenario. A proposed assumption capturing future gas pipeline buildout was not included, with the NYISO citing insufficient information to translate future pipelines into quantifiable firm gas MW during winter peak periods, though it indicated it will continue to monitor the question.

What This Means

The selected set concentrates on a small number of variables that move reliability outcomes: how much demand materializes, how much of the aging fleet retires, and how many planned projects actually arrive. Scenarios A and H both adopt the 10,900 MW cost-allocated project set against the Base Case 6,300 MW, which is a substantial swing in assumed supply. Scenario C runs the opposite direction on project timing.

For developers, Scenario J is the one that treats contracted projects as arriving on schedule. It raises planned project inclusion from 6,300 MW to 7,000 MW by capturing projects with a Tier-1 REC or OREC contract regardless of progress toward other milestones.

The informational designation limits what these results can do in this RNA cycle. Scenario results will not by themselves declare a reliability need. The proposed scenario planning framework would change that, and the NYISO has said it is soliciting written feedback on the implementation in this RNA to inform that reform work.

Looking Ahead

Scenario analyses continue through August 2026, with results to be presented alongside the RNA results in September. The draft RNA report and stakeholder review are planned for September, followed by Operating Committee approval, MMU review and memo, Management Committee approval, and Board approval from October through November. We will continue to track the RNA as preliminary results are released.

About Luminary Energy

Luminary Energy LLC provides advisory services to wholesale power generators and market participants in NYISO and ISO New England. To learn more about Luminary Energy’s services or to connect with a member of our team, contact us at [email protected].