Lowest Achievable Emission Rate (LAER) Analysis

What is LAER?

The Lowest Achievable Emission Rate (LAER) is the most stringent emissions control requirement under the Clean Air Act. LAER applies exclusively to new or modified major stationary sources located in areas that do not meet the National Ambient Air Quality Standards (NAAQS), also referred to as non-attainment areas.

Unlike other control analyses such as Best Available Control Technologies (BACT), LAER is determined on a case-by-case basis and does not consider economic feasibility. It is a technology-forcing standard intended to push facilities toward the cleanest emission performance possible. As defined in 40 CFR 51.165(a)(1)(xiii), a source must meet the more stringent of the following two standards:

1. 1. The most stringent emission limitations contained in State Implementation Plan (SIP) of any state for that class or category of sources (unless the owner demonstrates it is not achievable)
   2. The most stringent emissions limitation which is achieved in practice by such class or category of stationary sources. This limitation, when applied to a modification, means the lowest achievable emissions rate for the new or modified emissions units within or stationary source. In no event shall the application of the term permit a proposed new or modified stationary source to emit any pollutant in excess of the amount allowable under an applicable new source standard of performance. Once LAER is determined, it sets the controlled emissions baseline for your project. This allows for accurate determinations of how much pollution must be controlled or offset as part of the Nonattainment New Source Review (NNSR) process.

How LAER is Determined

LAER is determined at the time of permit application on a case-by-case basis, using the most current emissions limits and control technologies available. This process is referred to as an “up-to-the-moment” determination. The category of sources can be researched for comparisons in the RACT/BACT/LAER Clearinghouse. A thorough LAER analysis typically involves several technical components including:

• • Achievability Benchmarking
  • Emission Limit Setting (Unit: pounds per hour, tons per year, etc.)
  • Technological Feasibility
  • Capture Efficiency
  • Monitoring and Testing

Post-LAER Determination Control Strategies

Once LAER has been established for a source or modification, facilities must implement appropriate emissions control strategies and prepare subsequent regulatory steps. Emission control strategies may be met through one or more of the following:

1. 1. Add-on Controls
   2. Process modifications
   3. Super-compliant materials
   4. Pollution prevention

Ongoing compliance documentation includes:

• • Monitoring plans
  • Testing protocols
  • Capture efficiency maintenance requirements
  • Long-term operational commitments

A complete air emissions inventory is essential for validating the effectiveness of LAER strategies and calculation of offsets. It should include:

• • Projected post-LAER emissions
  • Baseline pre-project emissions
  • Quantified emissions reductions from applied controls