Environmental Protection Agency (EPA) Methane White Paper Oil and Natural Gas Sector Leaks INGAA Comments

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1 Environmental Protection Agency (EPA) Methane White Paper Oil and Natural Gas Sector Leaks INGAA Comments 1. Introduction The Interstate Natural Gas Association of America (INGAA), a trade association of the interstate natural gas pipeline industry, submits these comments on the EPA s technical white paper, Oil and Natural Gas Sector Leaks (Leaks Paper). On April 15, 2014, the EPA released five technical white papers discussing potentially significant sources of emissions in the oil and natural gas sector. Specifically, the white papers focus on potential emissions and mitigation techniques for methane and volatile organic compounds (VOCs). INGAA is submitting separate comments on the three papers (Compressors, Leaks and Pneumatics) that address sources applicable to the interstate natural gas transmission and storage (T&S) sector. These comments address the Leaks Paper. In the Leaks Paper, EPA summarized its current understanding of VOC and methane emissions from this source category, and its current understanding of available mitigation techniques and the cost, effectiveness, and application of these techniques in the oil and natural gas sector. EPA has requested comment on 13 questions related to the contents and conclusions of the Leaks Paper. INGAA and its member companies have a long history of working collaboratively with a variety of stakeholders on numerous greenhouse gas (GHG) related issues, including methane quantification and mitigation. As such, INGAA welcomes the opportunity to contribute its knowledge of emissions and available control technologies. INGAA commends EPA for involving stakeholders and inviting comment on the methane white papers. Executive Summary INGAA has three general points in response to EPA s white papers. First, there are significant differences in the methane emission estimates produced by EPA s Inventory of U.S. Greenhouse Gas Emissions and Sinks (the National Inventory) and the Subpart W portion of its Greenhouse Gas Reporting Program (GHGRP) 1. There also are significant gaps in the information available. EPA needs to develop a systematic program to reconcile these differences and fill the gaps in order to support further discussion on methane reductions. Second, INGAA recommends additional discussion and analysis of the implications, including costs, of potential mitigation methods. Finally, EPA should recognize that new information will be available soon to supplement this discussion. 1 See and (Starting with the 2011 calendar year for Subpart W, the GHGRP requires pipeline companies to submit annual reports of GHG emissions for subject facilities. Pipelines must submit 2014 emission information for the fourth annual report by March 31, 2015).

2 In response to the Leaks Paper specifically, INGAA offers the following comments: 1. EPA should support directed inspection and maintenance (DI&M) as a mitigation strategy. It is one of the most efficient and cost effective mitigation strategies. 2. INGAA recommends EPA review of the Subpart W data to properly understand leak frequency and distribution. A growing body of work supports the premise that a few larger leaks contribute to the vast majority of emissions INGAA disagrees that all leaks are cost-effective to repair. Many factors influence a leak repair decision, including, but not limited to, emission rates, reliability, material and labor costs, and schedule constraints. 4. Available technologies, including optical gas imaging (i.e., infrared (IR) camera) and EPA Method 21, are adequate for detecting leaks. EPA should remove ambient/mobile remote monitoring as a leak detection technology. It does not identify a specific leak source and, therefore, cannot be used for that purpose. 5. Finally, EPA should acknowledge that one of the benefits of a pipeline safety integrity management program is a reduction in emissions. INGAA welcomes the opportunity to contribute to this discussion. Overview of INGAA Responses INGAA has attempted to answer each question to the best of its ability. Due to time and other limitations, however, INGAA has not answered all questions fully. For some questions, INGAA could not respond completely because this would require a significant long-term effort (e.g., a research program) that includes all stakeholders. For example, questions regarding technology prevalence, cost implications and technical feasibility impacts would entail an integrated research effort to provide a quality, validated and vetted answer. In most cases, however, INGAA has provided a thorough response with the information available while noting the gaps in existing data. Whenever possible, INGAA offers specific examples of field conditions and industry experience. Appendix A provides a quick reference to EPA s questions on leaks and INGAA s response. 2. Establish an Open Process that Involves All Stakeholders to Further Examine Methane Reduction Issues Other than the Natural Gas STAR program, EPA has focused its oil and gas industry GHG efforts primarily on quantifying or estimating methane emissions. EPA must consider a number of issues, including economic, operational and environmental issues as it moves toward a broader methane strategy. INGAA envisions a process that is transparent and inclusive of industry and other stakeholders to examine issues and potential strategies. This has proven effective at other federal agencies and for other EPA regulations. For example, EPA could host technical conferences similar to those 2 This is often referred to as the 80/20 rule or 90/10 rule (e.g., 90 percent or more of emissions are due to 10 percent or fewer of the leaks). Page 2 of 17

3 convened by the Federal Energy Regulatory Commission (FERC) to examine critical issues prior to initiating a rulemaking. 3 This process would provide an efficient and effective means to advance the current understanding of methane emissions and how to design effective programs. As an example, the EPA GHGRP is intended to develop improved GHG inventories and to inform policy decisions. 4 Subpart W of the GHGRP addresses T&S segment emissions from vents and equipment leaks, and companies have submitted three years of data to date. Data is publicly available for the 2011 and 2012 reporting years, 5 and indicate significant differences between Subpart W reporting and the U.S. National Inventory 6 for T&S sources. These differences are due in part to differences in scope but also other reasons. It is very important that these differences are understood and that a single accurate inventory is in place before EPA or industry can develop and implement effective and efficient mitigation strategies. These proposed technical conferences or workshops can provide EPA and industry the platform to discuss these important issues so that EPA s future methane reduction policies reflect all relevant analysis. 3. Sources of Information on Emissions and Reduction Opportunities 7 EPA has requested comment on whether the Leaks Paper appropriately characterizes the different studies and data sources. INGAA agrees that it is important to understand the sources of methane emissions, how those emissions are measured and reported, what reduction opportunities exist (and what is the cost associated with these opportunities). While the Leaks Paper provides a summary of several sources of information, the paper does not reflect the full breadth of valuable information available to EPA on the topic. Further, while the studies have been summarized, they are neither compared nor contrasted with each other or with other sources of similar information. It would have been valuable for EPA to provide a tabular summary that presents the primary results from each study in common engineering units in order to identify data gaps and inconsistencies. While it may not have been the intent of the Leaks Paper to compare or contrast information, such an exercise is necessary to determine if a particular study appropriately characterizes the data available. Further, a comparison of the studies would help identify conflicts and data gaps in the information. 3 FERC typically holds public technical conferences to gather information on important policy issues and to hear potentially competing positions in advance of issuing significant rulemakings. For example, in , FERC held a series of technical conferences to explore issues surrounding the increased use of natural gas for electric power generation and issues that may impede coordination between the gas and electric industries. After considering discussions raised by interested stakeholders at the technical conferences, and subsequent public comments, the FERC initiated two rulemakings that propose to address concerns raised by participants at the technical conferences. Technical conferences provide the benefit of educating the regulator and other stakeholders on a particular issue and facilitating a structured dialogue where stakeholders can debate the effectiveness or need for prospective action prior to the issuance in a proposed rulemaking. Often technical conferences can reveal stakeholder support for certain initiatives, identify potential flaws in certain proposals, and identify alternative ways to address the regulator s or stakeholders concerns. 4 See 40 C.F.R. Part 98 (2014). 5 EPA publishes GHGRP reporting results through its data publication tool, Facility Level Information on Greenhouse gases Tool (FLIGHT); see 6 Inventory of U.S. Greenhouse Gas Emissions and Sinks: , EPA 430-R (April 2014). This report presents the U.S. national GHG inventory from for anthropogenic sources (i.e., associated with human activity) and is referred to as the National Inventory in these comments. The report is updated annually. 7 This section generally responds to Leak Paper questions 1 and 2 (emissions studies and data sources). Page 3 of 17

4 Due to the limited comment period, INGAA did not have time to develop a definitive analysis of the various studies listed or a list of key studies that were not included. However, more detailed discussion below provides examples of data gaps or differences in the primary tools that are being used to inform the process (e.g., differences between Subpart W reporting and the National Inventory). In general, INGAA views the Leaks Paper as a summary of some information but not the full range of studies and data sources currently available. EPA s characterization that the studies presented in the paper are pivotal suggests that EPA considers them key to understanding these issues. INGAA would caution EPA against placing excessive weight on this limited information since other studies, not referenced in the Leaks Paper, may be based on the same or similar data sets but reach different conclusions. INGAA also urges EPA to elaborate on how it arrived at its cost analysis for mitigation measures. Cost estimates are sensitive to assumptions and inherent data inconsistencies. Costs vary over time and with location and chosen technology. As presented by EPA, the 2014 study by ICF, Economic Analysis of Methane Emission Reduction Opportunities in the U.S. Onshore Oil and Natural Gas Industries, (ICF paper) 8 appears to be the primary source of information on evaluating cost-effective emissions reduction opportunities. However, the ICF paper has several limitations such as only including emissions mitigation options for a subset of emission sources, only addressing one mitigation technology or work practice for these select sources (i.e., alternatives are not addressed), and generally not addressing uncertainties or presenting ranges associated with emission mitigation costs and performance. Further, several other sources of similar information have not been referenced. In fact, cost-effectiveness has been examined by a number of organizations such as the International Petroleum Industry Environmental Conservation Association (IPIECA) 9 and the Intergovernmental Panel on Climate Change (IPCC). 10 Cost effectiveness has also been a topic during the United Nations Framework Convention on Climate Change (UNFCCC) events. Given the significance of understanding the costs associated with various methane reduction technologies in crafting a comprehensive costeffective reduction strategy, the Leaks paper should expand the discussion to describe more fully the body of available information, including key parameters and assumptions that impact cost analyses. As an example, the differences between Subpart W data and the National Inventory for T&S sources affect the calculation for potential achievable reductions and thus have economic analysis implications. New sources of information soon will become available that will significantly add to the understanding of methane emissions and reduction opportunities in the T&S sector. Specifically, the Pipeline Research Council International (PRCI) 11 is completing a report summarizing GHG emission reduction technologies and work practices applicable to natural gas pipeline compressor stations. The PRCI work will identify existing and commercially available GHG emission reduction technologies and work practices for pipeline compressor stations, as well as 8 Economic Analysis of Methane Emission Reduction Opportunities in the U.S. Onshore Oil and Natural Gas Industries, ICF International, Oil and Natural Gas Industry Guidelines for Greenhouse Gas Reduction Projects, March Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC). 11 The Pipeline Research Council International (PRCI) is the global collaborative research development organization of, by, and for the energy pipeline industry. Page 4 of 17

5 identify technologies in development. The report will evaluate technical and economic viability of existing and developmental GHG emission reduction technologies and work practices. While this report has yet to be released, PRCI has permitted INGAA to acknowledge the draft document for the purposes of our comments. More detail on leak emissions reduction technologies and costs is provided in comments below. 4. National Estimates of Methane Emissions and Methane Emission Factors, Activity Data, and Calculation Methodologies 12 EPA has asked for comment on the national estimates of methane emissions and methane emission factors, activity data, and calculation methodologies. While there are several sources of information on methane emissions from the natural gas system, the two primary sources of GHG emission data are the National Inventory and the EPA GHGRP. The EPA compiles both a topdown estimate of GHG emissions (i.e., National Inventory activity data uses data such as facility count and miles of pipe to estimate emissions) and detailed bottom-up reporting (GHGRP). Using other common vernacular, the National Inventory is commensurate with a Tier 1 or Tier 2 estimate (i.e., using activity data at the facility or large unit level), while Subpart W of the GHGRP uses Tier 3 (more granular source or component level activity data) or Tier 4 (detailed source level data or direct measurement) estimates. These two reports use different methods for estimating methane releases and do not include all of the same sources of releases. Accordingly, there currently is no single compilation that comprehensively and accurately addresses all sources of methane released by the T&S sector. While the National Inventory and the GHGRP produce consistent estimated emissions from some sources (e.g., the natural gas production segment), there are significant differences for the other segments of the natural gas system. There likely are multiple reasons for the disparity, including differences in the methodologies used in the two programs, and the specific sources being measured and included for reporting. For example, EPA updated key National Inventory estimates for the production segment based on more recent data, including Subpart W data. In contrast, EPA has not yet updated its key estimates for the T&S segment, and it does not appear that EPA has compiled or analyzed results based on thousands of measurements for T&S sources completed in response the GHGRP reporting requirements. INGAA suggests that the approach used for production can also be used to improve the estimates for the T&S sector and to serve as a more accurate basis for determining costs and mitigation opportunities. Work to reconcile these estimates remains an area of needed analysis before drawing any definitive conclusions about the total level of methane emissions from natural gas pipelines or definitively addressing related questions about mitigation and costs. The need for more current data and analysis on methane emission levels is highlighted by the fact that most T&S emission factors used for estimating methane emissions are based on a limited set of data that is approximately two decades old. The emission factors that are used to calculate methane emissions for both the National Inventory Report and for some Subpart W sources, have typically been in place since the 1990s and need to be updated. For T&S, the National Inventory (and other published papers and studies) primarily rely on emission factors 12 This section generally responds to Leaks Paper questions 1 and 2 (emissions studies and data sources), 3 and 4 (emission reductions & leak detection), 5 (impact of facility attributes on emissions), and 6 and 7 (leak detection technologies and efficacy). Page 5 of 17

6 derived from an EPA Gas Research Institute (GRI) study 13 that was completed in the early 1990s and published in These factors may not accurately reflect natural gas transmission methane emissions because operating practices, as well as the efficiency of operating equipment, have improved over the past 20 years. INGAA urges EPA to initiate a program to use the T&S data from 2011, 2012 and 2013 GHGRP reporting to support development of improved emission factors and improved emission estimates for the T&S segments. The GHGRP also has some limitations, including reliance on dated emission factors and exclusion of smaller facilities and smaller sources at subject facilities. Subpart W also does not require reporting of known sources, such as rod packing emissions in not operatingpressurized (i.e., standby) mode, and centrifugal compressor emissions from dry seals. However, analysis of the reported data should significantly improve the understanding of methane emissions from the T&S sector, especially where measurement is required. Future improvements in estimates of aggregated methane emissions, along with use of Subpart W direct measurements to update emission factors, can lead to more accurate estimates overall. INGAA asks that EPA work with the industry to develop emission factors for the sources with new measurement data available. Emissions Studies Leaks Emission Factors, Activity Data and Emission Estimates 14 As noted above, while the emission studies listed in the Leaks Paper provide a sampling of available information, other valuable sources are available. For example, the Leaks Paper lists two Clearstone Engineering Reports from 2002 and 2006 that are from a collaborative project that investigated emissions and the effectiveness of DI&M at processing and gathering facilities. These projects were subsequent to the original EPA-GRI study, and there were additional papers published in the late 1990s and early 2000s that discussed similar projects at transmission and storage facilities. This work included facilities in both the U.S. and Canada. In addition, there are reports available that EPA has used for other purposes, such as development of equipment leak emission factors used for T&S sources in Subpart W of the GHGRP. Thus, the listed sources represent a sample but not an all-inclusive list of available studies and data. For transmission, Table 2-4 presents emissions from the EPA-GRI study. We point out that this Table does not reflect the data provided in the narrative and has internal inconsistencies that need to be corrected. The presentation of data confidence intervals are in this table (and selected others) is very helpful and an important consideration. However, confidence intervals are not consistently presented and needs to be consistently used to provide a rudimentary understanding of the relative accuracies and uncertainties for the various studies. Emission estimate uncertainties are an important consideration but methods can vary from report to report. Thus, unless each listed report is reviewed in detail, it is not possible to understand accuracy and uncertainty for the various studies, so meaningful comment on study efficacy cannot be offered. 13 Methane Emissions from the Natural Gas Industry, EPA/GRI report (June 1996) at: This 15-volume compendium of reports is from an EPA/GRI study published in 1996 that remains a seminal reference on methane releases from natural gas systems. These reports and related data are referred to as the EPA-GRI Study in this paper. 14 In addition to text above, this section generally responds to Leaks Paper questions 1 and 2 (on emissions), 3 and 4 (emission reductions and leak detection), 5 (impact of facility attributes on emissions) and 6 (leak detection technologies). Page 6 of 17

7 A more comprehensive list of reports and leak emissions-related documents could be compiled, but a higher-priority endeavor might involve a better characterization of the strengths and weaknesses of available documents, identifying data or information gaps and defining a programmatic approach for resolving discrepancies and addressing data gaps differences. INGAA cannot now provide a comprehensive response because there was limited time to respond to the white papers. In addition, INGAA believes there is a general need to develop a systematic approach for compiling and analyzing information, understanding and reconciling differences in available information, identifying data gaps, and developing an agreed up inventory. There are also important issues regarding the breadth of each listed study. For example, some studies present emissions data or estimates (where emissions data may be from other projects) and then add an analysis on mitigation or costs. Thus, not all listed studies are original work regarding emission estimates, and there may be issues with assumptions regarding mitigation or costs. Also, some of the listed studies are focused on production or other upstream operations and not transmission or storage. 15 In general, the studies presented use common and accepted methods for estimating leak emissions. Leaks are a more complex and complicated emissions source to understand, but have a relatively long history of accepted methods. EPA s focus should be on studies that provide original data where leaks are not only detected but also measured, because this provides a more complete understanding of leaks. Other emission factor-based data to estimate leak rate can also be useful but provide less insight. For example, Subpart W of the GHGRP requires leak surveys for transmission, storage, and gas processing. The surveys identify the number of leaks by component type (e.g., connector, open-ended line, etc.) and then use a component-specific leaker emission factor to estimate emissions. With three years of Subpart W GHGRP reports submitted to date, many leak surveys have been completed and information on leak frequency is available within the Subpart W database. While that data can be insightful as to the prevalence of leaks, it does not provide new information on leak rates because emission factors are used for the emission calculation. At this time, natural gas industry stakeholders are compiling information from Subpart W reporting for T&S sources, but have not completed analysis of the data. The compressor-related measurements required for Subpart W measure leaks in some cases. Several source types are measured in defined compressor operating modes in the compressor measurement program. The sources includes vented emissions (e.g., from reciprocating compressor rod packing). As discussed in INGAA comments on the Compressor Paper, this also includes sources that are considered leaks in these white papers, including reciprocating compressor isolation valve leakage in shutdown mode, reciprocating compressor blowdown valve leakage in standbypressurized mode and operating mode, centrifugal compressor isolation valve leakage in shutdown mode, and centrifugal compressor blowdown valve leakage in operating mode. EPA s methane papers address leaks within the Leaks Paper and compressor venting in the Compressor Paper, but there is some overlapping and potentially conflicting content. For example, on page 3 of the Leaks Paper the reference to compressor seals as a potential leak source is not clear as it could be interpreted to mean reciprocating compressor rod packing, which is addressed in the Compressor Paper. As discussed in the Compressor Paper, compressor emission factors are sometimes a composite that includes leaks and vented emissions. For example, reciprocating 15 INGAA is not familiar with several of these listed studies and does not plan to review documents that are not related to the T&S sector. Page 7 of 17

8 compressor emission factors from the EPA/GRI study include both rod packing emissions (covered in the Compressor Paper) and leaks from isolation and blowdown valves (covered in the Leaks Paper). The Compressor Paper explains complications and errors that can result when using such emission factors to assess baseline emissions and potential reductions. Although not readily apparent when reviewing Subpart W reports, direct measurement data are available for compressor isolation valves and blowdown valves, because measurement of leaks from these compressor valves are required for transmission, storage, and gas processing facilities. A project being conducted by the Pipeline Research Council International (PRCI) is compiling and analyzing this data. At this time, detailed analysis has not been completed, but 2011 and 2012 reported data show that over 4,000 leak rate measurements from isolation and blowdown valves have been completed at T&S facilities. These measurements are separate from rod packing venting and wet seal degassing vent emissions measurement that are the province of the Compressor Paper. It is imperative that this measurement data be compiled, analyzed, and understood, so that Subpart W results fulfill the GHGRP objective of providing improved information to inform policy decisions. Through the PRCI project and related INGAA activities, the gas industry will have new and significant additional data to provide to EPA regarding methane emissions from the T&S sector. Natural gas transmission stakeholders welcome the opportunity to work with EPA on analyzing and understanding these data. Subpart W and National Inventory Emission Estimates and Discrepancies As discussed in INGAA comments on the Compressor Paper, the grouping of compressor-related emissions can cause confusion. Different studies and emission factors may treat compressorvented emissions (e.g., from rod packing) and leak-related emissions from compressor isolation valves and blowdown vent valves differently. For the purposes of Subpart W reporting, leaks from the isolation valves and blowdown valves (in the associated operating modes) are measured and reported as compressor emissions, which also included rod packing (for reciprocating compressors) and degassing vent emissions (for centrifugal compressors). Compressor emission factors from the EPA-GRI study, conducted in the 1990s, integrate these emission sources into a composite emission factor that considers the emission source and time in the related operating mode. Emission factors from the EPA-GRI study are used for National Inventory estimates for the T&S segments. Separately within Subpart W, (other) emissions from equipment leaks are reported, which addresses components, including some compressor related components such as fuel lines that are not specifically addressed by Subpart W direct measurement. Further, there are disparities in the Subpart W reported results for compressors, with a significant difference for centrifugal compressors. At this time, it is not clear how the different sources (i.e., vents versus valve leaks) contribute to the disparities. However, it is important to understand the data and reconcile differences in the historical estimate from the National Inventory and estimates based on recent Subpart W measurements. To summarize the differences explained in more detail in comments on the Compressor Paper, when Subpart W results are adjusted (scaled up) to use the same activity data as the National Inventory: (1) reciprocating compressor emissions are over 50 percent higher in the National Inventory than emissions based on Subpart W data; and (2) centrifugal compressor emissions are 20 times higher in the National Inventory than emissions based on Subpart W data. Page 8 of 17

9 Subpart W reports equipment leaks based on a leak survey and leaker emission factors (separate from the compressor valve leakage discussed above) and that data can be scaled up and compared with the National Inventory, which uses facility count as the activity data for estimating leak emissions from compressor stations. Based on an initial analysis, Subpart W data has been compiled from 315 transmission facilities that completed leak surveys in 2011 (i.e., this is about 1/5 to 1/6 of the total T&S facilities in the U.S.). A direct comparison indicates that the equipment leak estimate from the National Inventory is over 14 times higher than Subpart W reported emissions. When the Subpart W data is scaled up based on average emissions per facility and using the National Inventory facility count, the National Inventory estimate is over 2.5 times higher than an estimate based on Subpart W data. As noted, data compilation and review are ongoing, and additional insight may be gained that can be shared with EPA. At this time, the reason for the discrepancies is not clear. It is also not clear how EPA plans to use this Subpart W data to understand emissions and assess whether the national inventory estimate should be revised. INGAA members and other industry operators are expending considerable resources to complete compressor measurements of vented emission and valve leakage, as well as annual facility leak surveys. Thousands of measurements and hundreds of leak surveys have been completed to date and ongoing annual measurement is currently required. It is imperative that this significant dataset be used to improve the understanding of emissions from T&S facilities and inform policy decisions. If not, the GHGRP is not fulfilling its objective. INGAA recommends that EPA develop a comprehensive, systematic plan to compile, review and analyze this data. GHGRP results should be the building block of future emission estimates. These data need to be understood, and differences with other data or studies need to be reconciled. Until the emission estimates are more clearly understood, it is not possible to accurately assess emissions reductions or costs associated with mitigation. Finally, INGAA believes that careful review and understanding of new data from Subpart W is important to advance the understanding of leak frequency and distribution, which have implications for emissions and appropriate mitigation strategies. A growing body of work supports the premise that a few larger leaks contribute the vast majority of emissions. This is often referred to as the 80/20 rule or 90/10 rule (e.g., 90 percent or more of emissions are due to 10percent or fewer of the leaks). Many studies support this assertion (e.g., the original EPA-GRI study, the EPA-sponsored Clearstone Studies listed in Table 2-1). A clear understanding of this phenomenon is needed so that appropriate leak mitigation strategies can be defined. Mitigation is discussed further below. Emissions Estimates and Leak Detection 16 Leak Paper questions 3 and 4 inquire about emissions estimates and associated leak detection methods. Emissions estimates are discussed above. Regarding leak detection techniques and methods, the Leak Paper adequately discusses the suite of technologies and methods that are available. This includes newer technology (e.g., optical gas imaging i.e., the IR camera) and longstanding methods e.g., Method 21 which includes methods that range from soap bubbles to 16 See Leaks Paper questions 3 and 4 (emission reductions and leak detection) and 6 (leak detection technologies). Page 9 of 17

10 analyzers ( sniffers ) that measure hydrocarbons. The technologies and methods identified are established and adequate for leak detection, and are generally applicable across facility types. However, the Leak Paper also includes ambient/mobile monitoring as a leak detection technology. INGAA understands that mobile monitoring has been used in recent studies to identify atmospheric methane and estimate the flux rate (i.e., emissions) attributable to an upwind source. While this method/technology may serve a purpose for assessing total emissions from a facility or upwind source, it should not be considered a leak detection technique, which requires the ability to pinpoint specific leaks coming from individual points within a T&S facility with hundreds or even thousands of components spread across several acres. As discussed below in the mitigation section, it is important for the technique to identify the specific source of the leak i.e., the leaking component such as Method 21 or an IR camera. Ambient/mobile monitoring does not identify the leak source for a T&S facility and, therefore, should not be identified as a leak detection technology. Question 4 also inquires about ongoing or planned studies. INGAA strongly recommends the design and implementation of a systematic, comprehensive study to assess Subpart W data and other data to improve the current understanding of emissions. As noted, PRCI is compiling and analyzing Subpart W data from transmission companies (i.e., PRCI and INGAA members) and that information will aid in the understanding of methane leaks and mitigation practices. Several transmission companies are also participating in an emission study with the Environmental Defense Fund (EDF). The EDF study includes onsite direct measurement and mobile tracer flux measurements of T&S facilities, and results should be available later this year. INGAA suggests that a collective effort between EPA and industry is needed to understand Subpart W data, other existing data, and these new results so that more definitive conclusions can be reached on leak emissions from T&S facilities. Factors Affecting Emissions from Leaks Question 5 asks about facility types or other attributes that may result in higher leak emission rates. INGAA believes that a study would be required to answer this question. INGAA agrees that the factors listed by EPA are logical parameters to include in a study design, such as equipment type and count, age, maintenance history, and gas quality (e.g., sour versus sweet gas), since they could impact leak profiles. 5. Leak Detection Technology 17 The discussion above reviews leak detection technology Method 21 and IR cameras as it relates to identifying and estimating emissions. The Leaks Paper captures the methods and technology commonly used for locating leaks, and these have a long history associated with VOC emissions. In recent years, the IR camera has been added as a leak detection tool, and it is widely used for the annual surveys required by Subpart W of the GHGRP. 17 This section responds to Leaks Paper questions 3 and 4 (emission reductions & leak detection), 5 (impact of facility attributes on emissions), 6 and 7 (leak detection technologies and efficacy), 8 (prevalence), 10 (mobile monitoring and optical imaging), and 13 (technology innovation). Page 10 of 17

11 In general, technologies should be applicable at any type of facility, but some techniques may have greater utility at some facility types. For example, an IR camera facilitates leak screening of elevated and inaccessible vents that are common at T&S compressor stations. INGAA understands that ambient/mobile monitoring is being used in some studies, and some INGAA members are collaborating with EDF on a study that uses tracer flux measurement with an instrumented van. However, that technology should not be considered for leak detection, because for leak detection to be useful it must pinpoint the exact source of the leak. Mobile monitoring cannot provide that functionality. It is important to note that these technologies and methods are associated with finding leaks. Mitigation approaches discussed below include DI&M, which includes measuring leak rates when a leak is found. While leak detection technology is relatively robust, leak rate measurement approaches such as the high volume sampler and calibrated bag methods are more complex and time consuming. Advances in leak measurement technologies are desirable, such as advancing the IR camera to provide leak quantification or leak rate approximation and binning (e.g., small leak, larger leak worth further scrutiny). At this time, INGAA is not aware of studies or research that would develop or improve technology for leak rate measurement. In question 10, EPA requests comment on using ambient/mobile monitoring in conjunction with IR camera technology for leak detection. INGAA reiterates that ambient/mobile monitoring for leak detection at T&S facilities is inappropriate and unnecessary for this application. The use of an IR camera is robust and accurate enough to identify leaks quickly and efficiently without the need of supplemental ambient/mobile monitoring equipment. Pairing with mobile monitoring does not provide useful additional leak information beyond what the IR camera provides, and it actually may reduce the effectiveness of a leak detection survey due to its additional resource and time requirements. It would also add technology and support labor costs. As discussed below, the principles for implementing leak mitigation are fairly well understood, and mobile monitoring technology is neither needed nor effective for T&S facilities. Finally, question 8 requests feedback on the prevalence of leak detection technologies and question 7 inquires about costs and efficacy. INGAA is aware that multiple methods are often used for a leak survey depending on the source e.g., Method 21 to screen leaks, acoustic methods to detect through-valve leakage, IR camera for elevated components. However, INGAA is not aware of the prevalence or preferential use of certain techniques over others. An answer to this question cannot be provided without conducting a survey to understand operator practices. There may be reasons to use different technologies within a single survey, depending upon the situation. For example, an IR camera may facilitate quicker leak screening but can also be limited by weather conditions and other factors. The equipment cost generally is much higher than other methodologies available. Method 21 may be preferred in some cases to assess the leak relative to a threshold (e.g., 10,000 ppmv). All of the standard methods are viable and used in practice, and factors that may affect use for a particular site or survey are best left to the specific company to determine the most effective tools to identify leaks for each of their facilities. INGAA takes issue with some information included in the Leaks Paper, but due to the short comment deadline cannot provide a detailed critique of all of areas of disagreement in these comments. For example, the paper notes that an IR Camera can monitor nearly two thousand Page 11 of 17

12 pieces of equipment per hour at a refiner (or over 30 per minute). That is likely an over-estimate for most facilities and technology users. 6. Mitigation Techniques and Costs 18 The cost of leak mitigation techniques vary and are generally based on the leak definition and the leak repair decision. For example, a Method 21 threshold (e.g., 10,000 ppmv screening value) is one basis for defining a leak. Conventional leak detection and repair (LDAR) programs that are in place for VOC emissions generally include such a definition. If above the threshold, repair is required but qualifiers need to be considered, such as issues associated with elevated components, delay of repair criteria, cost and availability of replacement components, additional gas venting that would occur when the component(s) are replaced, etc. Another approach that differs from LDAR is DI&M, which was used by some voluntary participants in the Natural Gas STAR program and is well documented in EPA literature 19 and other public domain documents. 20 For compressor stations, INGAA believes that DI&M considers the key qualifiers and provides the flexibility to identify and address the highest priority leaks that warrant repair. DI&M survey costs are higher than conventional LDAR because leak rates must be measured using a high volume sampler, calibrated bag, flow meter or other appropriate method. The Natural Gas STAR Lessons Learned document provides additional detail on DI&M, and INGAA welcomes the opportunity to discuss DI&M further with EPA. The premise of DI&M is that typically, the largest leaks occur at just a few sources and it is not always economical to repair every leak. INGAA agrees because many factors can affect repair costs. Papers that espouse the theory that it is economical to repair all leaks were not scrutinized, but perfunctory review indicates that questionable or simplistic assumptions were used, such as a single or limited number of costs defined for repair. Repairing all leaks is not always prudent since the cost of the repair may far exceed the benefit of eliminating a small leak. Many factors can affect leak repair costs, which is a reason that INGAA supports DI&M for compressor stations rather than LDAR programs based on the premise that any leak should be repaired. Factors affecting leak repair costs include: Component type (e.g., valve, pump, rod packing flange, etc.); Component location with the facility (e.g., access, elevation); The ability to repair and action required (e.g., tighten a connection, partial disassembly of simple component to replace a gasket, facility shutdown and major equipment disassembly) or the need for replacement; Material needs and purchase and delivery times or availability of spare parts; Additional support or material costs; Facility operational constraints (i.e., lost operational time due to the need to shut down or isolate the component); 18 This section responds to Leaks Paper questions 9, 11 and 12 (leak mitigation and costs). 19 Directed Inspection and Maintenance at Compressor Stations, Lessons Learned from EPA Natural Gas STAR Partners, EPA430-B , see: (October 2003). 20 For example, see the two Clearstone reports, which were EPA sponsored studies, in Table 2-1 of the Leaks Paper. Page 12 of 17

13 Lost product (e.g., need to blow down equipment for access); Standard labor time required to repair the leak; Engineering design support for more complex replacements requiring piping modifications or similar actions; Specialized labor or technical expertise needed for repair or replacement; and Impacts to upstream or downstream operations and customers. A case-by-case evaluation is needed to better understand the cost implications of a repair decision. Some repairs can be made easily and quickly, while others may take considerable planning, timing and scheduling prior to implementation. DI&M provides a logical thought process for the repair decision and allows operators to focus on larger leaks (as appropriate) while also addressing quick and easy repairs that may not have high leak rates. Some of these factors are considered in LDAR regulatory programs (e.g., 40 C.F.R. 60, Subpart KKK) and include provisions regarding repair timing and deferral (e.g., at next scheduled plant turn-around). Leak repair programs need to consider these same repair or replacement considerations, timing and scheduling requirements. The DI&M process is explained in the referenced documents, including existing EPA material, and INGAA can provide additional information if needed. A PRCI report is nearing completion that provides additional discussion on leak mitigation technologies and work practices and associated costs, and that report includes a detailed discussion of DI&M. Pipeline Safety Integrity Management Will Reduce Methane Emissions Finally, EPA should acknowledge that integrity management programs intended to improve pipeline safety have the ancillary benefit of reducing operating methane emissions. However, integrity management requirements can also result in additional methane emissions from pipeline blowdowns related to maintenance projects. When and where possible, pipeline companies employ pump-down and recompression to minimize the release of methane during these activities. Inline inspection (ILI) technologies that can measure the material strength of pipelines as effectively as, or better than, hydrostatic testing would eliminate the need for hydrostatic testing. This could greatly reduce the cost and disruption caused presently by such testing to confirm material strength and contribute to reducing pipeline methane emissions by eliminating the need to remove natural gas from the pipeline prior to testing. To achieve these benefits, it will be critical for the Pipeline and Hazardous Materials Safety Administration (PHMSA) to authorize the use of the new ILI technology in lieu of hydrostatic testing. 7. Coordinate Methane Initiatives across Agencies and Establish a Primary Point of Contact As part of the Obama administration s Climate Action Plan, the Administration has initiated several efforts that address methane reductions, including revisions to the EPA Natural Gas STAR Program, launch of the Quadrennial Energy Review, revision of EPA s GHGRP, the five Page 13 of 17

14 methane white papers and plans to revise regulations to control VOC emissions, and possibly methane emissions from the oil and gas sector. 21 This level of simultaneous activity on a common issue challenges the industry and other stakeholders, and coordination between industry and between policymakers is crucial. Therefore, INGAA recommends that the Administration establish a primary point of contact responsible for ensuring coordination across the multiple federal agencies and departments tasked with methane-related initiatives impacting the T&S sector. Ideally, this point of contact would provide guidance and assistance in the development, interpretation and implementation of methane policies. It can be difficult for the pipeline industry to manage the numerous and sometimes duplicative requests for information from multiple agencies and departments. As questions arise about the overall climate change strategy, it would be extremely helpful to have this same primary point of contact within the Administration to discuss methane and other GHG reduction issues, opportunities and policies. 8. Conclusion INGAA and its members are committed to reducing methane emissions in a prudent and environmentally responsible manner, and are undertaking initiatives to understand the sources of T&S sector methane emissions and identify the most significant sources and the most costeffective methane emission reduction strategies. In summary: 1. EPA should support DI&M as a mitigation strategy. It is one of the most efficient and cost effective mitigation strategies. 2. INGAA recommends a careful review of the Subpart W data to properly understand leak frequency and distribution. A growing body of work supports the premise that a few larger leaks contribute to the vast majority of emissions. 3. INGAA disagrees that all leaks are cost effective to repair. Many factors influence a leak repair decision, including, but not limited to, emission rates, reliability, material and labor costs, and schedule constraints. 4. Available technologies, including optical gas imaging (i.e., IR camera) and EPA Method 21, are adequate for detecting leaks. EPA should remove ambient/mobile remote monitoring as a leak detection technology. It does not identify a specific leak source and, therefore, cannot be used for that purpose. 5. Finally, EPA should acknowledge that one of the benefits of a pipeline safety integrity management program is a reduction in emissions. 21 For example, potential revisions to 40 C.F.R., Part 60, Subpart OOOO. Page 14 of 17

15 INGAA appreciates the opportunity to comment on the Leaks Paper and will continue to provide EPA with additional information as it becomes available. Sincerely, Lisa S. Beal Vice President, Environment and Construction Policy Interstate Natural Gas Association of America Page 15 of 17

16 Appendix A Question and INGAA Response 1. Did this paper appropriately characterize the different studies and data sources that quantify VOC and methane emissions from leaks in the oil and natural gas sector? Responses are found in sections three and four of the INGAA comment document. 2. Please comment on the approaches for quantifying emissions and on the emission factors used in the data sources discussed. Please comment on the national estimates of emissions and emission factors for equipment leaks presented in this paper. Please comment on the activity data used to calculate these emissions, both on the total national and regional equipment counts. Responses are found in sections three and four of the INGAA comment document. 3. Are the emission estimating procedures and leak detection methods presented here equally applicable to oil and gas production, processing, and transmission and storage sectors? A limited response is found in section four and five of the INGAA comment document. 4. Are there ongoing or planned studies that will substantially improve the current understanding of VOC and methane emissions from leaks and available techniques for detecting those leaks? Please list the additional studies you are aware of. A response is found in section four and five of the INGAA comment document. 5. Are there types of wells sites, gathering and boosting stations, processing plants, and transmission and storage stations that are more prone to leaks than others? Some factors that could affect the potential for leaks are the number and types of equipment, the maintenance of that equipment, and the age of the equipment, as well as factors that relate to the local geology. Please discuss these factors and others that you believe to be important. A limited response is found in section four of the INGAA comment document. 6. Did this paper capture the full range of technologies available to identify leaks at oil and natural gas facilities? Responses are found in sections four and five of the INGAA comment document. 7. Please comment on the pros and cons of the different leak detection technologies. Please discuss efficacy, cost and feasibility for various applications. Responses are found in sections four and five of the INGAA comment document. 8. Please comment on the prevalence of the use of the different leak detection technologies at oil and gas facilities. Which technologies are the most commonly used? Does the type of facility (e.g., well site versus gathering and boosting station) affect which leak detection technology is used? A response is found in section five of the INGAA comment document. Page 16 of 17