Partial Repeal of the Carbon Pollution Standards and How Capacity Factor Affects New Combustion Turbines
A final rule was signed by EPA Administrator Lee Zeldin on September 14, 2026 repealing many of the 2024 Carbon Pollution Standards (CPS) governing greenhouse gas (GHG) emissions from fossil fuel-fired power plants under Clean Air Act section 111.
What was repealed:
Emission guidelines for existing coal/gas/oil-fired steam generating units — including the requirement that long-term coal plants use 90% carbon capture and sequestration (CCS), and that medium-term coal plants use 40% natural gas co-firing.
CCS-based standards for coal plants undergoing large modifications.
"Phase 2" CCS-based standards for new base-load combustion turbines.
EPA’s repeal also updated language in 40CFR60 Subpart TTTTa. While the Phase 2 standards for new base load combustion turbines were repealed, which would have required 90% CCS by January 1, 2032, the Phase 1 efficiency-based standards were left in place for all new turbines.
Changes to Capacity Factor Definitions for Combustion Turbines
Most coverage of EPA's September 2026 repeal of the Carbon Pollution Standards (CPS) focuses on the headline: the CCS mandates are out. The 2024 CPS put new turbines into three capacity-factor-defined tiers with Best System of Emission Reduction (BSER) requirements and the 2026 repeal changed some of those:
Subcategory | Capacity factor | BSER (before repeal) | BSER (after repeal) |
Base load | ≥40% | Two-part: (1) highly efficient generation, effective immediately; (2) 90% CCS by 1/1/2032 | Only part (1) survives — efficiency-based limit, no CCS |
Intermediate load | Below 40%, above 20% | Highly efficient simple-cycle generation | Unchanged — never had a CCS component |
Low load | Below 20% | Lower-emitting fuels | Unchanged — never had a CCS component |
But the amendatory text in 40 CFR 60.5580a also changes how new combustion turbines are sorted into load tiers. The "and" and "or" in those definitions decide which turbines land in which tier.
Three tiers, two criteria
New combustion turbines are classified by how much of their potential electric output they sell to the grid. The rule tests this with two criteria at once: a 12-month rolling total and a 3-year rolling average. In some cases the new rule uses "both" criteria or "either" criteria which determine their CO2 emission limits.
Tier | Test |
Base load | More than 40% on both 12-month rolling total and 3-year rolling averages |
Intermediate load | More than 20% on both windows, and 40% or less on either window |
Low load | 20% or less on either window |
What didn't change: the base load definition
"Base load combustion turbine" is not among the definitions this rule revises. The amendment updates intermediate load and low load. Base load keeps its existing language: more than 40% of potential electric output as net-electric sales on both a 12-month rolling total and a 3-year rolling average basis.
This definition makes sure that one strong year (12-month rolling total) doesn't make a unit base load, and neither does one strong three-year stretch (3-year rolling average).
What did change: the intermediate and low load definitions
The new "either" logic in the low-load and intermediate-load definitions is similar to the unchanged base-load definition, but provides better assurance to the operator regarding which limit applies.
At the 20% line: a unit has to clear 20% on both windows to no longer be low load. If the units factor is 20% or below on just one window and it is low load.
At the 40% line: a unit has to clear 40% on both windows to be base load. If either window is at or below 40%, it falls to intermediate.
For example, a turbine at 45% on one window and 35% on the other. It isn't base load, because it didn't clear 40% on both. It isn't low load either. The new intermediate ceiling catches it.
The gap this closes
The earlier definitions used "both" at every boundary. Under that wording, a turbine at 45% and 35% satisfied neither the base-load test (not above 40% on both) nor the old intermediate test (not at or below 40% on both). A turbine at 15% on one window and 25% on the other failed both the old low-load test and the old intermediate floor. Both ended up in classification limbo.
The new language fixes this. Mixed units at the 40% line go to intermediate. Mixed units at the 20% line go to low load.
What this means in practice
The change is not a loosening of the regulation. Nothing here makes base load easier to reach, since that bar is untouched. The "either" tests mainly make sure units straddling a boundary are assigned to a tier rather than left unclassified.
It also matters more with the CCS requirement gone. Base load status no longer triggers a 90% CCS mandate, but the tiers still determine which efficiency or fuel-based limit applies to a new turbine.
How Alliance Technical Group Helps
As requirements change, facilities need a clear understanding of which standards apply and reliable data to demonstrate compliance. Alliance Technical Group brings together air quality consulting, industry-leading data acquisition systems, one-stop shop for all things CEMS, and stack testing to support your facility’s compliance program. Whether you’re evaluating requirements for a new turbine or reviewing your existing monitoring and reporting practices, Alliance works with your team to address the details and keep your compliance program aligned with your operations.
