DAQ seeks public comment on letting some non-emergency engines be treated by actual emissions with reporting triggers

Brad Nelson of the Division of Air Quality presented proposed amendments to 15A NCAC 02Q .0807 that would extend existing Title V exclusionary provisions to some non-emergency stationary reciprocating internal-combustion engines by allowing facilities to base potential emissions on measured annual fuel consumption and established emission factors rather than assuming 8,760 hours of operation.

Nelson said the change targets intermittent or noncontinuous processes (for example, construction equipment or car crushers) whose actual annual operation and fuel use produce far lower emissions than the 8,760-hour potential. As an example, he described two 500-horsepower diesel engines: using AP-42 emission factors and 8,760 hours would yield a potential NOx emission rate above a 100 tons-per-year major-source threshold, but if the facility reports actual fuel use that reflects far fewer operating hours, the calculated actual emissions can remain below Title V thresholds.

Nelson also gave a data-center example in which new certified engines would each emit about 12.55 tons per year, and DAQs calculations showed a site could install up to seven such engines before reaching 100 tpy of the controlling pollutant. DAQ said it converted emission factors into an annual diesel-fuel threshold of 646,116 gallons across a site as one way to show compliance under the proposed approach.

Under the draft approach, facilities with facilitywide emissions below 75% of major-source thresholds would report annually; facilities at or above 75% would report quarterly so DAQ can learn sooner if a site is approaching major-source status. Nelson said facilities would need to submit a permit-applicability demonstration and meet enforceable conditions to qualify for the exclusion.

Committee members pressed DAQ on monitoring and safeguards against short-term pollution spikes during thermal inversions; staff responded that the proposed change does not alter applicable federal or state emission standards or control requirements and that the reporting triggers are intended to provide DAQ earlier notice when a facility's actual use approaches major-source thresholds. Several members asked whether the RAIA assumptions had been reviewed by counsel; Nelson said that step had not been done at the time of the presentation.

A motion to proceed to the EMC to request approval to proceed to public comment and hearing on the proposed amendments was made, seconded and carried by the committee with no recorded opposition.