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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF 

 AIR AND RADIATION 

Petroleum and Natural Gas Systems (Subpart W) of the Greenhouse Gas Reporting 

Rule 

Docket: EPA-HQ-OAR-2009-0923 

Title: Minimum Gas Processing Throughput 

Summary: The purpose of this analysis is to determine a clear distinction between gas 

processing facilities and gas gathering facilities for subpart W of the MRR. 
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Minimum Gas Processing Throughput 

The purpose of this analysis is to determine a clear distinction between gas processing 

facilities and gas gathering facilities for subpart W of the MRR. By removing gas 

gathering and boosting equipment from today’s final rule, there could be uncertainty as to 

exactly where the gas processing segment starts in relationship to gas gathering. Today’s 

final rule applies two criteria for gas processing segment: fractionation and throughput. 

All processing plants with fractionation are processing facilities. Those gas processing 

plants that do not have fractionation, but have gas throughput capacity greater than 25 

mmscfd are processing facilities. 

Data 

In considering this question of what distinguishes gas processing from gathering, EPA 

consulted the Oil and Gas Journal Worldwide Gas Processing Survey,1 This survey lists 

all the U.S. Gas Processing Plants, including their capacity and unit processes (e.g. 

fractionators, acid gas removal, sulfur plant, etc. This survey illustrates the throughput 

capacity of all processing facilities that owner-operators submitted for their processing 

plant(s). Not all of these plants have fractionation. 

EPA then considered the GHG emissions from these processing plants. The subpart W 

Technical Support Document2 lists all of the processing plants from the OGJ survey, 

along with calculated GHG emissions. The method of calculating processing plant 

emissions is described in the TSD. This data was plotted for processing plants without 

fractionation in Figure 1 and for all processing plants in the OGJ survey in Figure 2. 

Analysis

Figure 1 plots the 2005 throughputs for gas processors (processing plants without 

fractionation), in million cubic feet per day, listed in the OGJ 2006 Worldwide Gas 

Processing Survey against the total emission for each plant determined in the threshold 

analysis. The 2005 natural gas throughput and emissions are plotted using a logarithmic 

scale. The vertical line marks the 25,000 tonne CO2e threshold for reporting to the MRR. 

The horizontal line marks a reporting throughput floor at 25 million cubic feet per day 

just below the smallest gas processing plant that will have to report emissions under 

subpart W. The smallest gas processing plant without fractionation has a throughput of 

1.5 mmcfd and is well below the subpart W reporting theshold. 

Figure 2 plots the 2005 throughputs for every processing plant, in million cubic feet per 

day, listed in the OGJ 2006 Worldwide Gas Processing Survey and the total emission for 

each plant determined in the threshold analysis. The 2005 natural gas throughput and the 

emissions are plotted using a logarithmic scale. Again, the vertical line marks the 25,000 

tonne CO2e threshold for reporting to the MRR. The horizontal line at 25 million cubic 

 

1

 OGJ. (2006) Worldwide Gas Processing Survey. Oil and Gas Journal <http://www.ogj.com> 2

 EPA. (2010) Technical Support Document. Subpart W. Final Mandatory Reporting Rule. Environmental 

Protection Agency. Appendix C. Docket No. (EPA-HQ-OAR-2009-0923) 
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feet per day from Figure 1 marks the potential throughput floor for processing facilities. 

It is observed that this throughput floor would exclude more than 200 processing plants 

that have fractionation from the definition of a processing facility, including 

approximately 40 that are above the 25,000 tCO2e reporting threshold. EPA believes that 

there are gas gathering and boosting stations with throughputs above the minimum 

throughput of the smallest non-fractionating process plant in the OGJ survey: 1.5 mmcfd. 

Conclusion 

EPA concluded that fractionation alone would not suffice as a definition for gas 

processing, as there are several plants in the OGJ survey with emissions well above the 

reporting threshold and a few near enough to the threshold that combustion emissions 

alone may not require them to report to subpart C. Furthermore, excluding some 

fractionation plants from the OGJ survey does not conform with the existing Clean Air 

Act facility definition; most, if not all of these fractionation plants are likely permitted. It 

is difficult to argue that a gas processing plant with fractionation, represented in the OGJ 

gas processing survey, is a gathering/boosting station. Therefore, today’s final rule 

defines gas processing facilities as those with fractionation and those without 

fractionation with a gas throughput capacity of 25 mmcfd and above. 

 
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Figure 1. Natural Gas Processing Plant Throughput v. Total Emissions for Gas Processors Only 

1

10

100

1000

1

,000 10,000 100,000 1,000,000

Process and Combustion Emissions (tCO2e)

2005 Natural Gas Processing Plant Throughput (MMcfd) 25 Million Cubic Feet per Day

25,000 metric tons CO2e 
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Figure 2. Processing Plant Throughput v. Processing Facility Emissions 

0.101.00

10.00

100.00

1,000.00

10,000.00

1,000 10,000 100,000 1,000,000 10,000,000

Process and Combustion Emissions (tCO2e)

2005 Natural Gas Processing Plant Throughput (MMcfd) 25 Million Cubic Feet per Day

25,000 metric tons CO2e