Air Quality Plan; Arizona; Maricopa County Air Quality Department; New Source Review; Emission Reduction Credits-Rule 204
Key claim: EPA is proposing to let Maricopa County, Arizona, allow off-road engine fleets to earn pollution credits by retrofitting or replacing engines, which major industrial plants could then use as offsets when they expand.
Abstract
(Proposed Rule · Environmental Protection Agency) The U.S. Environmental Protection Agency (EPA) is proposing to approve a revision to the Maricopa County Air Quality Department (MCAQD or “Department”) portion of the Arizona State Implementation Plan (SIP). This revision establishes a federally enforceable program allowing nonroad engine fleet owners/operators to generate emission reduction credits (ERCs) by either retrofitting their nonroad engines or replacing their nonroad engines with lower-emitting nonroad engines while meeting other Clean Air Act (CAA or “Act”) requirements. These ERCs are intended for use as offsets for major stationary sources under the Department’s Nonattainment New Source Review (NNSR) program. We are proposing to approve a local rule to allow for the generation of ERCs through voluntary nonroad engine emission reductions under the CAA.
Why this matters
Nonattainment areas like metropolitan Phoenix must find real emission reductions to offset any new or expanding major industrial source, and the supply of credits often constrains industrial growth. Allowing fleet owners of off-road diesel engines to generate ERCs by retrofitting or replacing engines expands that supply while targeting a large unregulated source of NOx and PM, but it also shifts pollution accounting from stationary smokestacks to mobile fleets whose real-world reductions can be harder to verify.