Dear Sir or Madam:

On April 15, 2014, the U.S. Environmental Protection Agency (EPA) Office of Air Quality Planning and 

Standards released for external peer review five technical white papers on potentially significant sources 

of emissions in the oil and gas industry sector. These white papers focus on technical issues covering 

emissions and mitigation techniques that target methane and VOC emissions from compressors, well 

completions and ongoing production of hydraulically fractured oil wells, equipment leaks, liquids 

unloading, and pneumatic devices. The Texas Commission on Environmental Quality (TCEQ) appreciates 

the opportunity to comment on these white papers. TCEQ’s comments are provided below.

In general, more data is needed to substantiate and confirm the emission estimates presented in the 

EPA’s white papers. While it is not unusual to establish control requirements based on expected 

emissions from a facility or single source, the studies and emission estimates used in the white papers 

rely on the EPA’s definition of “facility” as established for the EPA’s Greenhouse Gas Reporting Program 

(GHGRP). 

In general, a “facility” for purposes of the GHGRP means all co-located emission sources that are 

commonly owned or operated. However, the GHGRP has developed a specialized facility definition for 

onshore production. For onshore production, the “facility” includes all emissions associated with wells 

owned or operated by a single company in a specific hydrocarbon producing basin. [1] 

(1 Oil and Natural Gas Sector Hydraulically Fractured Oil Well Completions and Associated Gas during 

Ongoing Production, page 21, footnote 9; Oil and Natural Gas Sector Liquids Unloading Processes page 

5, footnote 2; Oil and Natural Gas Sector Pneumatic Devices, page 20, footnote 11.)

The use of this definition makes determining emissions from each unit or piece of equipment difficult, if 

not impossible to verify. Since control is usually required for each individual piece of equipment, the lack 

of this information makes evaluating the cost effectiveness of any potential controls or mitigation 

techniques similarly impossible. 

Where the studies referenced in the white papers used a more traditional understanding of the term 

“facility”, meaning each individual piece of equipment, compressor, or controller, the TCEQ has concern 

about the limited data sets used and would recommend additional studies to verify the accuracy and 

representativeness of the numbers and factors derived. The great variation in the composition of oil and 

gas that exists across different fields can result in vastly different emissions profiles and thus additional 

research is warranted to verify the accuracy and representativeness of the expected emissions. 

Moreover, if the information in the white papers or later studies is relied upon to develop required 

controls or mitigation techniques, the TCEQ recommends consideration of a range of controls or 

techniques that would correlate to the differing standards, or factors based on the particular 

composition or characteristics of the material being handled or processed. This approach would help to 

ensure the appropriate level of control for the material and provide the flexibility that a “one-size-fitsall” approach cannot achieve. 

Additionally, while the TCEQ encourages innovation and development of new processes and controls for 

air emissions in general, when establishing any standards or requirements it is crucial to rely on proven 

control technologies that are commercially available. The failure to do so may lead to a new standard or 

control that is not achievable for all of the affected facilities. For example, in the evaluation of 

Compressor Emissions Mitigation Techniques for Reciprocating Compressor Gas Recovery, EPA refers to 

a system developed by REM Technology, Inc. that captures gas that would otherwise be vented and 

routes it back to the compressor engine to be used as fuel. However, no cost data was available to 

properly evaluate the technology as a viable, cost-effective control or mitigation technique and, 

although commercially available, it is unknown if this system is available to the scores of facilities that 

may need to use it if required. The TCEQ encourages the EPA to evaluate only proven control 

technologies that are commercially available in volumes that could support the industry as a basis for 

establishing any future standards or requirements.
If you have any questions about these comments, please contact Mr. Michael Wilson, P.E., Director, Air 

Permits Division, Office of Air, at (512) 239-1922, or at mike.wilson@tceq.texas.gov.

Sincerely,

Steve Hagle, P.E., Deputy Director, Office of Air

Texas Commission on Environmental Quality

steve.hagle@tceq.texas.gov

512-239-1295