Analysis of the Proposed Supplemental Interstate Transport Rule

For this proposed action, EPA used the same baseline power sector analysis as was used as part of the Good Neighbor Plan for the 2015 Ozone NAAQS (GNP), which was finalized on March 15, 2023. EPA used one new IPM run for this proposed action. This IPM run can be found below, as well as the documentation and IPM runs used for the GNP included for reference.

Documentation for the EPA's Power Sector Modeling Platform v6 using IPM:

EPA's baseline power sector analysis for this proposed action and for the GNP used an Updated Summer 2021 Reference Case with updates to the fleet and some modeling assumptions.

Air quality modeling and corresponding analysis utilized these power sector emissions projections. This platform builds from the EPA's Power Sector Modeling Platform v6 using IPM Summer 2021 Reference Case and incorporates incremental updates.

NEEDS for Updated Summer 2021 Reference Case: NEEDS rev: 08-03-2022 (xlsx) (4.06 MB)
NEEDS rev: 10-14-22 (xlsx) (4.06 MB) : Used in Engineering Analysis for budget setting.
Updated Summer 2021 Reference Case Incremental Documentation for the 2015 Ozone NAAQS Actions (pdf) (146.87 KB, Jan, 2023)

IPM Run Files

Download IPM run files for the Final GNP using the links in the table below. Click on the IPM run name in the first column of the table below to download a file. The files are posted in one of two formats, a zipped archive or an excel spreadsheet, and contain detailed IPM input and output files (i.e., .DAT, System Summary Report, .RPE, and RPT files) for the listed runs. Review the guide of IPM input and output files.

More detailed information on the modeling framework, specific scenarios, assumptions, and other important details of the analysis can be found in the Regulatory Impact Analysis (pdf) (7.68 MB, March, 2023) that accompanies the Final Good Neighbor Plan.

IPM Run Name	IPM Run Description
Air Quality Modeling Base Case (zip) 2023 Parsed File (xlsx) (8.17 MB) 2025 Modeling Parsed File (xlsx) (8.52 MB)	Model run used for the air quality modeling base case at steps 1 and 2, which includes the national Title IV SO₂ cap-and-trade program; NO_X SIP Call; the Cross-State Air Pollution trading programs, and settlements and state rules. It also includes key fleet updates regarding new units, retired units, and control retrofits that were known by Summer of 2022.
Illustrative Final Rule (zip) 2025 Illustrative Parsed File (xlsx) (8.54 MB)	Model run used for 2026 air quality analysis of the final Federal Good Neighbor Plan (GNP). Includes the national Title IV SO₂ cap-and-trade program; NO_X SIP Call; the Cross-State Air Pollution trading programs, and settlements and state rules. It also includes key fleet updates regarding new units, retired units, and control retrofits that were known by Summer of 2022. Includes the illustrative final rule. For details, please see Chapter 4 of the RIA for the GNP.
Sensitivity Air Quality Modeling Base Case with IRA (zip)	Model run used for the air quality modeling base case sensitivity analysis in the presence of the IRA at steps 1 and 2, which includes all information from the Air Quality Modeling Base Case as well as parameters reflecting the key provisions of the Inflation Reduction Act of 2022. For details please see Appendix 4A of the RIA for the GNP.
Sensitivity Final Rule with IRA (zip)	Model run used for 2026 air quality sensitivity analysis of the GNP. Includes the national Title IV SO₂ cap-and-trade program; NO_X SIP Call; the Cross-State Air Pollution trading programs, and settlements and state rules. It also includes key fleet updates regarding new units, retired units, and control retrofits that were known by Summer of 2022. Includes the illustrative final rule. For details please see Appendix 4A of the RIA for the GNP. This is the baseline used in the EIA for the evaluation of this proposed rule.
Sensitivity Final Rule with IRA and Proposed Rule (zip)	Model run used for 2026 air quality sensitivity analysis of the proposed rule. Includes the national Title IV SO₂ cap-and-trade program; NO_X SIP Call; the Cross-State Air Pollution trading programs, and settlements and state rules. It also includes key fleet updates regarding new units, retired units, and control retrofits that were known by Summer of 2022. Includes the illustrative final rule. For details, please see Sections 3 and 4 of the EIA for this rulemaking.

Supporting Files

Flat File Methodology EPA Platform v6 Updated Summer 2021 Reference Case (pdf) (383.71 KB, Jan, 2023)
Flat File Inputs EPA Platform v6 Updated Summer 2021 Reference Case (xlsx) (1.63 MB)
Post Processing Emissions Factors PM CO VOC NH3 Updated Summer 2021 Reference Case (xlsx) (4.83 MB)

All files including the corresponding version of NEEDS, IPM run files, incremental documentation, and support files used in the Air Quality Modeling can also be found in the docket for the GNP. The only exception is the IPM run files for the run “Sensitivity Final Rule with IRA and Proposed Rule”, which is located in the docket for this action.

For the Updated Summer 2021 Reference Case results and documentation, please see: