Q505. How does a natural gas compressor station that operates compressors for natural gas transmission and an emergency generator determine subpart applicability?

A505. For the purpose of determining the applicability of 40 CFR part 98 for the 2010 reporting year, the facility should calculate the emissions from the gas compressors pursuant to 40 CFR 98.30(a)(2). So long as a the emergency generators meet the definition of “emergency equipment” as stated in 98.6, emissions from the emergency generators are exempt and should not be calculated.  If the facility is subject to 40 CFR part 98, you should report combustion emissions pursuant to the applicable requirements of subpart C (General Stationary Fuel Combustion Sources).  Pursuant to 40 CFR 98.2, if a facility’s calculated total annual emissions are less than 25,000 metric tons of CO2e and the facility does not contain a source category listed in Table A-3 of 40 CFR part 98, subpart A, then the facility does not have to report under 40 CFR part 98 as a direct emitter.

For the purpose of determining the applicability of 40 CFR part 98 for the 2011 reporting year, the facility should calculate the combustion emissions pursuant to 40 CFR part 98, subpart C (General Stationary Fuel Combustion Sources) and equipment leak and vent emissions pursuant to 40 CFR part 98, subpart W (Petroleum and Natural Gas Systems).  Transmission compressor stations follow subpart C for calculating combustion-related emissions and subpart C exempts emergency equipment.  Based on the information provided, if the facility is subject to 40 CFR part 98, you should report combustion, equipment leak, and vent emissions pursuant to the applicable requirements of the subparts.

Information and resources regarding the applicability and requirements of the aforementioned subpart are available at: http://www.epa.gov/ghgreporting/reporters/subpart/w.html.