Industry: Air Emissions Controls

Introduction

In January 2026, the U.S. Environmental Protection Agency finalized long-awaited updates to the New Source Performance Standards (NSPS) for stationary combustion turbines—marking the first major revision since 2006. With power generation developers increasingly dependent on flexible, rapid-deployment solutions such as temporary turbines and trailer-mounted generation, these changes bring important implications for project scheduling, emissions compliance, and technology selection.

This blog outlines what has changed, how the new temporary turbine subcategory works, and what developers should consider as they plan new installations or short-term power solutions.

Updated NOx Standards for Modern Turbines

The EPA’s final rule restructures emissions requirements by grouping turbines into subcategories based on:

• Heat input (MMBtu/hr)
• Thermal efficiency (≥38% or <38%)
• Expected utilization (12-month capacity factor)
• Fuel type and load conditions

The changes align emissions expectations with what modern combustion controls and SCR technology can realistically achieve.

Key NOx Standard Revisions

• Large, high-utilization turbines (>850 MMBtu/hr, >45% CF) must now meet single-digit NOx emissions using combustion controls + SCR.
• Medium and small turbines retain combustion-controls-only pathways with updated ppm limits.
• Natural gas remains the basis for hourly emissions performance.
• SO₂ standards remain unchanged, with more flexible compliance options.

For developers, these updates will influence technology specifications, EPC execution planning, and permitting timelines.

The New Temporary Turbine Subcategory

The 2026 rule introduces a dedicated regulatory framework for stationary temporary combustion turbines, addressing an industry need for short-term, flexible power during outages, commissioning, construction sequencing, or emergency support.

Key Features of the Temporary Turbine Category

• Applies to turbines up to 850 MMBtu/hr
• Limited to 24 months at a given location
• NOx standard: 25 ppm using combustion controls only
• Reduced monitoring and recordkeeping
• Exempts certain portable Title II-covered engines
• Prevents “serial swapping” to extend temporary status

This category enables faster, more efficient deployment of turbine temporary power and trailer-mounted power generation systems—without excessive compliance burden.

MW Output Estimates Based on EPA Heat Input Categories

Because EPA regulates turbines by heat input (MMBtu/hr), developers often need a practical translation into MW output. Using typical turbine thermal efficiencies, here is a rough guide:

Turbine Category	Heat Input	Efficiency	Approx. MW Output
Large	>850 MMBtu/hr	≥38%	~95 MW
Medium	50–850 MMBtu/hr	≥38%	5–95 MW
Small	≤50 MMBtu/hr	30–38%	4–6 MW
Temporary Turbines	≤850 MMBtu/hr	30–38%	5–95 MW

These estimates help developers size temporary solutions and anticipate the emissions requirements tied to turbine selection.

Economic and Project Delivery Implications

According to EPA’s Economic Impact Analysis, the updated rule is expected to:

• Reduce annual NOx emissions by up to 296 tons by 2032
• Save industry up to $87 million over eight years
• Focus SCR deployment only on large, high-duty units where it is cost-justified

For developers, this results in:

• Lower capital costs for many turbine classes
• Continued viability of non-SCR combustion turbines
• Streamlined permitting for temporary deployments
• Enhanced flexibility in project scheduling and outage planning

The regulatory environment now better supports short-term and contingency power solutions.

What Developers and Turbine Representatives Should Do Now

1. Assess Turbine Classification Early
Efficiency, utilization, and heat input now directly determine regulatory requirements.

2. Factor in Temporary Power Strategy
Temporary turbines provide cost-effective coverage for outages, interconnection delays, and commissioning.

3. Coordinate with OEMs and EPC Partners
Thermal efficiency thresholds and NOx limits influence model selection and long-term operating strategy.

4. Review Documentation Requirements
Temporary status requires manufacturer certification and periodic (five-year) testing records.

Conclusion

The EPA’s updated NOx standards significantly modernize the emissions landscape for new and modified turbines. For developers and OEM representatives, the changes reinforce the need to plan turbine selection and temporary power strategies early in the project lifecycle. With the introduction of the temporary turbine subcategory, the industry gains a more flexible, streamlined path for meeting both short-term and long-term power generation needs.

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If you need support navigating the new NOx standards, evaluating turbine options, or planning temporary generation during outages and construction, our team is here to help you develop a compliant and cost-effective strategy.

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Author(s)

Marc Collins

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