Best Available Control Technology (BACT) Analysis

What is BACT?

A Best Available Control Technology (BACT) Analysis is required under the Clean Air Act’s Prevention of Significant Deterioration (PSD) permitting program, as outlined in 40 CFR §52.21(j). BACT represents an emission limitation based upon the maximum achievable reduction for each regulated air pollutant emitted from a new or modified emissions unit. The purpose of BACT is to ensure that air emissions are minimized to the greatest extent while preserving economic growth potential, particularly in attainment areas (i.e. geographic region where air quality meets or better than EPA standards).

Key elements of BACT include:

• • Pollutant and Unit-Specific Application – BACT must be evaluated for each pollutant and each emissions unit subject to PSD review.
  • Comprehensive Control Options Review – The analysis must consider the full range of demonstrated options.
  • Scaled Level of Detail – The depth analysis should vary with the relative magnitude of reduction emissions achievable.
  • Quantifiable Emissions Limit – BACT emission limits must be expressed in measurable units (e.g. pounds per hour) and process unit variables based on maximum process capacity.
  • Enforceability of Controls – All selected controls must be enforceable (e.g. Stack Testing, Continuous Emissions Monitoring System, detailed recordkeeping, etc.)

Note: Permitting authorities do not perform BACT analysis for applicants. Each facility is responsible for the submission of a complete and robust BACT evaluation as part of their PSD air permit application.

When is BACT Analysis Required?

A BACT determination is required when a project triggers PSD permitting, which applies in attainment/unclassifiable areas and to:

• • New major stationary sources
  • Major modifications of existing facilities that result in a significant emissions increase of any regulated NSR pollutant

Each regulated pollutant is subject to a separate BACT evaluation, and each emission unit or fugitive emissions source contributing to the increase must be analyzed.

BACT Determination Process

States with EPA-approved programs, such as Tennessee, follow the BACT guidelines as outlined in EPA’s New Source Review Workshop Manual.

Step 1: Applicability & Preliminary Screening Prior to initiative BACT analysis, facilities must:

• • Determine pollutant applicability – Identify each regulated pollutant emitted in quantities exceeding PSD significant thresholds.
  • Confirm emission unit applicability – Assess all sources, including process stacks and fugitive emissions, that contribute to increased emissions.
  • Identify energy, environmental, and economic sensitives – Flag potential issues that may constrain certain control technologies.
  • This initial screening ensures that BACT is applied to areas where it’s required.

Step 2: Conducting the Top-Down BACT Analysis

EPA’s top-down approach follows a 5-step structure to select the most effective, feasible control technology for each pollutant and emission unit. The process follows:

1. 1. Identify All Available Control Technologies
      1. Transferable and innovative control technologies
      2. Processes that inherently produce less pollution
      3. Various configurations of the same technology which achieve different control efficiencies
   2. Eliminate Technically Infeasible Options
      1. Infeasible due to ineffectiveness at controlling emissions from the specific process being reviewed
      2. Infeasible due to a reduction in product quality (e.g. different paint formulas, paint application methods, alternative flux materials, etc.)
   3. Rank Remaining Technologies (i.e. Highest to Lowest Control Efficiency)
   4. Evaluate Energy, Environmental, and Economic Impacts
      1. Energy Impact – Address energy use associated with control system and direct effects of energy on facility
      2. Environmental Impact – Associated with each alternative emission control system, both beneficial and adverse impacts
      3. Economic Impact – Direct costs, financial feasibility, local economic effects, annual cost compared to effective emissions reduced, etc.
   5. Select BACT
      1. Expressed as an enforceable emissions limit
      2. Accompanied by monitoring methods
      3. Supported by recordkeeping and operation conditions

 Step 3: Final Documentation & Permit Integration

To support the permitting agency review, BACT determinations must be fully documented. The permit application should include:

• • Control system proposals for all emission points
  • Alternative systems offering greater control
  • A reasonable defense of selected BACT
  • Monitoring and enforceability provisions tied to each emission limit

Our SEC experts are ready to support and ensure that your BACT submissions are aligned with EPA and state expectations, including all necessary components and logically structured.