Q498. Under subpart W, are we required to calculate potential GHG emissions from compressors at a natural gas processing facility that are only used for refrigeration and use 100% propane?

A498. In the situation where the facility is an onshore natural gas processing facility, 40 CFR 98.232 (d) states that onshore natural gas processing should report CO₂, CH₄, and N₂O emissions from the sources listed at 40 CFR 98.232(d)(1)-(11). If the compressed gas stream is 100% propane, then the emissions that vent directly to the atmosphere will not include CO₂, CH_4, or N₂O emissions and therefore will not have to be reported under subpart W. However, if the compressor leak or vent emissions are routed to a flare, then GHG emissions from the flare should be counted towards the reporting threshold of 25,000 mt CO₂e. Similarly, if the compressor driver is an engine or turbine, then GHG emissions from fuel combustion in the engine or turbine also should be counted towards the reporting threshold. If the facility exceeds the 25,000 mt CO₂e threshold, then the owner or operator must report the flared emissions as flare stack emissions under subpart W and the fuel combustion emissions for this compressor driver under subpart C.