What The EPA finalized in January 2026

The EPA finalized amendments to the NSPS for stationary combustion turbines under 40 CFR Part 60, subpart KKKKa. The updates focus on NOx and SO2 requirements and introduce clearer categories and compliance pathways that affect how many new turbines are evaluated and controlled.

Highlights include:

• A new applicability framework. The final NSPS applies to turbines that commenced construction, modification, or reconstruction after December 13, 2024, and it generally replaces older NSPS requirements for turbines subject to the new subpart.
• More refined NOx subcategories. EPA established size-based subcategories and further divided some turbines by utilization and efficiency. The final rule uses a 12-month capacity factor threshold of 45 percent to distinguish low versus high utilization units. It also uses an efficiency threshold of 38 percent (HHV basis) in certain categories.
• For some high-utilization large turbines, EPA concluded the best system of emissions reduction includes combustion controls plus selective catalytic reduction.
• A new “stationary temporary combustion turbine” subcategory. EPA finalized a subcategory for stationary temporary combustion turbines up to 850 MMBtu per hour used in temporary applications, with a distinct NOx standard and reduced monitoring requirements when specific conditions are met.  [1][2][6][8]

What “temporary” means under the updated NSPS

The updated NSPS introduces guardrails that matter for project planning and permitting strategy. The practical takeaway is that “temporary” has specific conditions, and it is not a label that can be stretched indefinitely.

A 24-month limit is the bright line. If a turbine remains in place longer than 24 months, EPA states it is not considered temporary for any period of its operation. EPA also notes that failing to meet applicable NSPS requirements in that situation can be an enforceable Clean Air Act violation.

Swapping turbines does not reset the clock. The rule is structured to prevent a revolving-door approach where one temporary unit is replaced by another to extend temporary status beyond 24 months.

Temporary turbines can still support planned work. EPA indicates temporary turbines may be used to replace generation when non-temporary units are taken offline, including for maintenance.

Reduced compliance burden does not mean no compliance. For the temporary turbine subcategory, EPA set a NOx standard of 25 ppm when firing natural gas and reduced monitoring, recordkeeping, and reporting requirements. However, owners and operators must maintain on-site documentation supporting compliance status, including manufacturer certification to the NOx standard and performance testing history for older turbines.  [1][6][8]

How this intersects with permits

NSPS is a federal emissions performance standard. Construction and operating permits are typically issued by state or local permitting authorities under Clean Air Act programs, often incorporating NSPS applicability, conditions, and compliance demonstrations.

In practice, NSPS applicability evaluations and “temporary” claims can become central to a permitting review. Projects can run into trouble when the operational reality of a turbine does not align with the original permitting assumptions, such as longer-than-expected deployment, higher utilization, or broader non-emergency use. Several industry summaries of the final rule note that while EPA introduced some streamlining concepts, agencies and stakeholders are paying closer attention to turbines that function like long-term generation.  [2][5][6][8]

How Encino can help

Encino supports customers by helping them evaluate requirements early, build a defensible permitting strategy, and reduce the risk of schedule impacts. For stationary combustion turbines, permitting support often includes:

• Applicability reviews, including NSPS subpart determination and temporary versus non-temporary evaluation
• Emissions estimating and documentation support aligned with agency expectations
• Permit strategy and coordination with state or local permitting authorities
• Compliance planning support, including recordkeeping setup and readiness for performance testing and documentation requirements
• Ongoing assistance when operational changes or equipment changes trigger permit updates

If your team is evaluating turbines for a new build, expansion, or temporary power plan, it is worth validating how the project fits under the updated NSPS structure and how that will translate into construction and operating permit requirements.

Checklist: What operators should do now

Use this checklist as a quick screen before you rely on “temporary” assumptions or move forward with procurement and installation.

Project definition

• Confirm whether the turbine is intended for emergency use only, planned outages, construction power, peak shaving, or ongoing generation.
• Document the anticipated installation date, start-up window, and expected removal date.
• Confirm fuel type and any expected switching scenarios.

NSPS applicability and category

• Determine whether the turbine falls under subpart KKKKa based on construction or modification timing.
• Identify the applicable size category and whether utilization or efficiency thresholds are likely to apply.
• If claiming “stationary temporary combustion turbine,” confirm the unit is within the eligible heat input range and intended use fits the rule’s temporary framework.

Temporary status reality check

• Validate that the turbine will be removed within 24 months and build an internal trigger to reassess if schedule slips.
• Do not assume unit replacement will preserve temporary status.

Permitting strategy

• Confirm whether a construction permit is required before installation.
• Confirm whether an operating permit update is needed based on emissions thresholds, source status, or permit conditions.
• Align your NSPS applicability analysis with what the state or local agency expects to see.
• Compliance documentation readiness
  For temporary turbines, verify manufacturer certification to the NOx standard and assemble required on-site documentation.
• Confirm whether performance testing is required or recommended for your unit and timeline.
• Set up recordkeeping and reporting processes before start-up, not after.

Stakeholder and risk management

• Plan for increased scrutiny if the turbine supports a large load, runs frequently, or remains in place for extended periods.
• If the project is public facing, anticipate questions about permits, emissions controls, and operating limitations.

[1][2][3][6][8]