Oil and Natural Gas Sector Synthesis Paper 

Peer Review Responses of Environmental Defense Fund

June 16, 2014 

EDF appreciates the opportunity to provide peer review responses to EPA’s 

White Papers, which evaluate emissions of volatile organic compound (“VOC”) and 

methane emissions from key sources in the oil and natural gas sector and describe costeffective mitigation measures to reduce these emissions. In addition to our responses on 

each of the individual papers, we provide this synthesis response to better characterize 

opportunities across papers and to identify cross-cutting themes that have emerged in our 

review. 

Our expert review of these White Papers is informed by our growing 

understanding of the urgent need to reduce emissions of methane and other harmful 

pollutants from the U.S. oil and natural gas sector. Recently, the Fifth Assessment 

Report of the Intergovernmental Panel on Climate Change (IPCC) concluded that 

methane is a much more potent driver of climate change than we understood it to be just 

a few years ago – with a global warming potential as much as 34 times greater than 

carbon dioxide (CO2) over a 100-year time frame, and 84 times greater than CO2 over a 

20-year time frame. Approximately one-third of the anthropogenic climate change we 

are experiencing today is attributable to methane and other short-lived climate pollutants, 

and about thirty percent of the warming we will experience over the next two decades as 

a result of this year’s greenhouse gas emissions will come from methane.1

 Climate 

scientists are now recognizing that avoiding catastrophic climate change will require both 

a long-term strategy to reduce carbon dioxide emissions and near-term action to mitigate 

methane and similar “accelerants” of climate change. As a recent article in the journal 

Science stated, “The only way to permanently slow warming is through lowering 

emissions of CO2. The only way to minimize the peak warming this century is to reduce 

emissions of CO2 and [short-lived climate pollutants].”2

 

Reducing emissions from the U.S. oil and gas sector is an indispensable part of 

such a comprehensive climate strategy. Oil and gas facilities are the largest industrial 

source of methane in the United States, accounting for approximately thirty percent of the 

nation’s total methane emissions.3

 Frequently, methane from oil and gas facilities is coemitted together with other harmful pollutants, including ozone precursors such as VOCs 

and carcinogenic substances such as benzene and other hazardous air pollutants 

 

1

 Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth 

Assessment Report of the Intergovernmental Panel on Climate Change (Thomas Stocker et al., eds. 2013). 

2

 J.K. Shoemaker et al., What Role for Short-Lived Climate Pollutants in Mitigation Policy? 342 Science 

1323-24 (2013). 

3

 EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012 (2012).
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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(“HAPs”).4 And because methane is a valuable commodity, reductions in methane 

emissions often pay for themselves due to increased resource recovery – making methane 

mitigation a low-cost (and sometimes negative cost) proposition. 

EPA’s White Papers, taken in context with the feedback and supplemental 

information we provide in our peer review responses, present a compelling overview of 

the scale and scope of emissions from these sources and support a conclusion that further 

action could mitigate emissions from each of the sources discussed in the White Papers. 

Although some uncertainty persists on the overall national emissions from the industry, 

we have a sufficient understanding of individual source types to provide confidence that 

significant benefits would result from implementing proven, practical strategies for 

emission reduction. 

This synthesis paper is organized as follows. Part I, below, focuses on national 

emissions estimates and contextualizes the significant mitigation opportunity identified 

by EPA’s five papers. Part II identifies synergies across the five papers, and Part III 

discusses continuous improvement. 

I. EMISSIONS, MITIGATION OPPORTUNITIES, COST & EFFECTIVENESS

Each of EPA’s White Papers presents detailed information on emissions, 

mitigation technology, cost, and effectiveness, organized by discrete, individual source 

types. Because of this focus, the papers do not emphasize a holistic picture of the 

national potential to reduce overall emissions from the oil and gas sector through 

expansive deployment of cost-effective and well-demonstrated mitigation technologies. 

One recent and compelling illustration of the national-level opportunity to reduce oil and 

gas sector emissions through the technologies outlined in the White Papers comes from 

ICF’s 2014 cost curve analysis.5

Table 1, below, presents information on national emissions from our review of the 

White Papers and underlying data, and Table 2 reproduces ICF’s results from table 4-1 of 

the cost curve analysis, highlighting the technologies EPA evaluated as part of the White 

Paper process. As we note in our White Paper responses, some of the technologies EPA 

presents provide an enhanced opportunity for emissions mitigation, and so certain of 

these numbers are conservative, though illustrative. 

Nearly all of the technologies EPA evaluated in the White Papers are also 

evaluated in the ICF Report and contribute significantly to ICF’s estimate that a 40% 

reduction in emissions is achievable in 2018 at a cost of under one penny ($0.01) per 

thousand cubic feet of gas produced. Oil tank vapor recovery units and pipeline venting 

 

4

Petron et al., 2014 A new look at methane and nonmethane hydrocarbon emissions from oil and natural 

gas operations in the Colorado Denver-Julesburg Basin, Journal of Geophysical Research: Atmospheres, 

online: 3 JUN 2014 DOI: 10.1002/2013JD021272.

5

 ICF International, Economic Analysis of Methane Emission Reduction Opportunities in the U.S. Onshore 

Oil and Natural Gas Industries B-6 (March 2014) [hereinafter “ICF Cost Curve Report”], available at 

http://www.edf.org/sites/default/files/methane_ cost_curve_report.pdf. 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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are not covered, however, and we urge EPA to consider these technologies as part of its 

evaluation of cost-effectiveness. Even so, the suite of technologies EPA evaluates are 

capable of reducing methane emissions by nearly 2.9 million metric tons or 37 percent of 

onshore emissions. This represents 93 percent of the total cost-effective mitigation 

potential highlighted in ICF’s report.6

 

6

Id. at Table 4-1. 
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TABLE 1: Summary of Likely Emissions Factors and National Emissions for White Paper S

Source Type 

Potential Range 

of Average 

Emission Factor 

Potential 

Range of 

National 

Annual CH4

Emissions 

Skewed 

Emissions 

Distribution? 

Assessment 

1. Equipment Leaks 

Production Leaks 

(non tanks) 

34 Mscf/yr-well 

(Allen) 190-400 Gg Yes 

Allen et al suggests national emissions from equimodestly higher than GHG Inventory; however thuncertainty about disaggregating the activity factsites, which are lumped in with production in the 

2. Compressor Seals

Reciprocating - Rod 

Packing

500-2,500 

Mscf/yrcompressor 280-560 Gg Yes 

Per compressor average emissions factor is compsomewhat higher than GHG Inventory estimate bemissions in the "operating-pressurized" mode. national estimate is based on the average of repoemissions per compressor in GHG RP times numbcompressors in GHG EI; high end doubles the estfor likely emissions in the "idle-pressurized" modtotal for rod packing is roughly 25% of total fugit

reciprocating compressors in the GHG EI. 

Centrifugal - Wet 

Seals 

1,000-8,000 

Mscf/yrcompressor 90 Gg Yes 

Per compressor average emissions factor is likely GRI/EPA estimate. National estimate is based on 

reported wet seal emissions per compressor in G

segment, times the number of centrifugal compr

segment in the GHG EI. The estimated 90Gg totaemissions is approximately 20% of the total fugit

centrifugal compressors with wet seals in the GH
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3. Pneumatic Devices

Controllers 4-30 Scf/hour- device 560 - 1,000 Gg Yes 

Emission factors are for sampled populations of d

production service, not specific device types, as ral, Prasino, Fort Worth, and GHGEI; scaled nationstrongly dependent on the assumed population memission range reported here includes, on low enestimate for transmission (210 Gg) added to the for production (330 Gg), and on the upper end, testimate added to the high end reported in Allen 

Pumps 10-30 scf/hour- device 35-100 Gg Unclear Low and high end of emission factor approximate

Allen et al and GHGRP and Prasino study, respectestimate from Allen et al. 

4. Liquids Unloading

Unloading wells that 

vent

152 - 320 

Mscf/well 274 - 321 Gg Yes Estimates of highest emitting wells are a substan

national emissions. 

5. Oil wells

Completions 

(Potential Emissions)

360 - 10,000 

Mscf/well 44 - 272 Gg Likely, Yes (2) Potential emissions per completion 2 - 4 orders o

than current emission factor in GHG Inventory 

Associated gas 258 Mscf/well 90 Gg Yes Emissions are known with relatively high confide

change depending on future growth of gas gathe

6. Aggregated Emissions by Site 

Production Sites (all 

sources including 

tanks, pneumatics, 

and compressors) 

400 - 1,500 

Mscf/yr-site N/A Yes 

Thoma ( 300-1,300 Mscfy/site) and Fort Worth (1

studies include tanks, pneumatics and compressohigher per site emissions than Allen et al (400 Ms

Transmission Stations 

(all sources) 

15,000-25,000 

Mscf/yr-site N/A Yes Subpart W reports for 462 Transmission Facilities 

emissions) 

Processing Plants 

(equipment leaks) 

66,000 - 81,000 

Mscf/yr-site N/A Limited Sample Size Clearstone I and Clearstone II averages for high- a

range, respectively (whole gas) 
TABLE 2: Mitigation Potential, Effectiveness and Cost of Key Control Strategies* 

*Adapted from ICF Report Table 4-1. Highlighted technologies were evaluated by EPA in the White 

Papers. Because EPA evaluated LDAR in the leaks White Paper and because this practice has broad 

applicability, we have included LDC Meters and Regulators even though the White Papers did not 

explicitly evaluate the distribution sector. Finally, the $0.66 / mcf reduced is another way to understand our 

earlier statement that a 40 percent reduction is achievable for under one penny of gas produced. The latter 

simply contextualizes total reduction costs in terms of overall gas production. 

II. CROSS-CUTTING THEMES & HOLISTIC OPPORTUNITIES

The White Papers largely evaluate mitigation opportunities by focusing on 

particular sources and examining emissions, the effectiveness of technologies in reducing 

those emissions, and costs. This approach has many advantages, and as we discuss 

above, it demonstrates that there are substantial sources of emissions in the oil and gas 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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sector and opportunities to reduce those emissions at modest, and sometimes negative, 

cost. 

Here, we supplement the analysis presented in the White Papers by highlighting 

cross-cutting issues that are common to all of the sources discussed in the White Papers. 

These cross-cutting considerations provide a fuller picture of the benefits associated with 

reducing emissions from the oil and gas sector. 

A. Emissions 

Because the White Papers focus on average emissions from individual sources or 

facility types, they may overlook key information regarding the nature and extent of 

emissions from the oil and gas sector.7 In particular, the distribution of emissions across 

sources, the multi-pollutant nature of these emissions, and insights from top-down 

emissions studies provide important, additional context for evaluating the effectiveness 

and benefits of mitigation measures. 

First, as we describe in our responses to each of the Papers, most of the emissions 

sources in the oil and natural gas sector exhibit a highly-skewed or “fat-tail” statistical 

distribution, in which a small number of “gross emitters” account for the vast majority of 

emissions. Figure 2 shows the distribution of emissions sources for compressor rod 

packing and wet seals, liquids unloading, pneumatic controllers, equipment leaks, and 

associated gas venting and flaring taken from several datasets. The presence of “gross 

emitters” is evident for each of these areas. 

The “gross emitter” phenomenon has important policy implications. Because the 

average emission factors used to develop official inventories may not reflect highemitting sources at the far ends of the distribution, the “gross emitter” phenomenon 

suggests that the aggregate benefits of emission mitigation measures may be greater than 

analyses of “typical” facilities would reflect. In addition, the heterogeneous distribution 

of emissions indicates that the cost-effectiveness of emissions mitigation can be enhanced 

by securing reductions at high-emitting sources. Lastly, several sources suggest that 

“gross emitters” can result from maintenance issues and malfunctions, rather than 

intrinsic source characteristics (like high-emitting pneumatic devices). 

Ultimately, the existence of gross emitters underscores that a comprehensive 

policy to address emissions is critical – one that focuses both on prevention of highemitting, systemic sources like pneumatic devices and on detection and remediation of 

leaking sources using approaches that are well-adapted to finding the highest-emitting 

sources and facilities. A well-designed leak detection and repair program can help 

identify routine fugitive emissions such as those described in the White Paper on 

equipment leaks and can also spot failing pneumatic devices, compressor seals, storage 

 

7

 Even so, fugitive emissions of methane from oil and natural gas sector are the largest industrial source of 

methane in the United States and the second largest source globally. See EPA. Overview of Greenhouse 

Gases: Methane Emissions, http://epa.gov/climatechange/ghgemissions/gases/ch4.html. 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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tank control equipment, isolation valves, and other sources which can become egregious 

sources if left unchecked. This is an often-overlooked and important benefit of LDAR 

that has broad relevance to multiple White Papers. 
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Figure 2. The relationship of the percentage of sources to the percentage of total emissions for rod packing

pneumatic controllers, liquids unloadings, equipment leaks, and associated gas venting & flaring. Rod pac

emissions are ranked by compressor, pneumatic controller and equipment leak emissions are ranked by counloading and associated gas venting & flaring emissions are ranked by well averages at the sub-basin/com

sources are the Greenhouse Gas Reporting Program 2012 data (GHGRP) and Allen, et al. 2013 (UT). 

0%

10%20%30%40%50%60%70%80%90%

100%

0% 10% 20% 30% 40% 50% 60% 70% 80% 

% of methane emissions

% of components or wells

Rod Packing (GHGRP)Wet Seals (GHGRP)Pneumatics (UT)Liquids Unloading (GHGRP)Equipment Leaks (UT)Associated Gas Venting & Flaring(GHGRP)
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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In addition to these distributional issues, EPA’s White Papers do not fully capture 

the multi-pollutant benefits of mitigating emissions from the oil and gas sector. As EPA 

continues to evaluate emissions mitigation opportunities, we urge the agency to consider 

not just methane and VOC reductions that may result from the measures outlined in the 

White Papers, but also reductions in HAPs like benzene, which is a known carcinogen. 

Indeed, as the ICF Cost Curve Report emphasized, the same mitigation measures that 

would achieve a 40% reduction in methane emissions in 2018 would likewise achieve a 

44% reduction in both VOCs and HAPs.8 Any analysis of oil and gas sector pollution 

mitigation that focuses on a single pollutant – whether that pollutant is methane, VOCs, 

or HAPs – understates the multiple dividends for public health and the environment that 

result from emission reductions in this sector. However, we do recognize that EPA may 

ultimately decide to focus on one pollutant as it considers appropriate regulatory and 

policy responses. If that is the case, an approach focused on reducing methane is likely to 

achieve the greatest multi-pollutant benefits because methane is the most ubiquitous of 

the three major categories of air pollutants associated with this sector, and is emitted in 

large quantities at every step in the supply chain. 

Finally, EPA presented only bottom-up emissions studies in the White Papers, 

and while we recognize these studies often provide direct information on equipment 

emissions factors, they paint an incomplete picture of overall emissions from this sector. 

In addition to these bottom-up studies, there have been numerous, recent top-down 

studies assessing oil and gas sector emissions across large geographic areas. Though 

these studies cannot attribute emissions to a particular piece of equipment, they do 

provide evidence of the magnitude of basin-wide emissions, uniformly suggesting these 

emissions are substantially greater than bottom-up inventories would predict.9

 

Accordingly, evaluating emissions holistically reveals additional, critical 

information that should inform EPA’s thinking on any future actions. In particular, the 

distribution of emissions across sources, which is generally concentrated in a relatively 

small percentage of high-emitting sources, suggests that leak detection and repair is an 

essential complement to one-time emissions reduction strategies like swapping highemitting for low-emitting pneumatic devices. Moreover, the data suggest that addressing 

these emissions has even greater benefits than EPA projected in the White Papers – both 

because of the multi-pollutant nature of oil and gas pollution and because top-down 

evidence suggests that methane and other co-emitted pollutants may be currently 

underestimated. 

B. Technology & Effectiveness 

Similarly, the White Papers evaluate the ability of technologies to reduce 

emissions from specific sources, but this approach, while needed, may inadvertently 

 

8

 ICF Cost Curve Report at 4-11 to 4-12. 

9

 A.R. Brandt, G.A. Heath, E.A. Kort, F. O’Sullivan, G. Pétron, S.M. Jordaan, P. Tans, J. Wilcox, A. 

Gopstein, D. Arent, S. Wofsy, N.J. Brown, R. Bradley, G.D. Stucky, D. Eardley, R. Harriss, 2014, 

Methane Leaks from North American Natural Gas Systems, 2014, Science, Vol. 343, 33-35. 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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overlook ways in which technologies can be leveraged or combined to achieve even 

greater emission reductions than a source-specific analysis would indicate. Indeed, a 

holistic assessment of mitigation approaches can reveal the potential for greater control 

effectiveness in two important ways: 1) broad applicability – once purchased, certain 

technologies can be applied comprehensively to various emissions points both within 

facilities and across the oil and natural gas supply chain; and 2) synergies – deploying 

certain mitigation measures in concert can enhance control effectiveness beyond what 

either technology could accomplish individually. 

1. Broad Applicability

At least two of the mitigation technologies presented in the White Papers have 

cross-cutting applications at multiple source types within a facility: leak detection 

technology, and gas capture technology. 

As we describe in our response to the Leaks White Paper, leak detection 

technologies, like IR cameras, are typically used to survey potentially leaking 

components over certain intervals of time. Once purchased, however, an IR camera can 

be used to search for emissions across a broad range of potentially leaking components at 

the same site, such as: 

• Valves and other components. LDAR can be effectively used to identify all 

manner of component fugitive emissions, including emissions from valves, 

flanges, connectors and open-ended lines. 

• Pneumatic Devices. Emissions associated with malfunctioning devices can be 

detected and mitigated using LDAR. 

• Storage Tanks. Significant emissions are often associated with open thief 

hatches and pressure relief valves that allow emissions to bypass control 

devices, which can be detected and mitigated using LDAR. Colorado now 

requires regular LDAR at new and existing storage vessels for this very 

reason. 

• Compressors. Fugitive emissions from sources other than wet seal degassing 

or deteriorating rod packing can be a significant source of emissions, and ICF 

found that LDAR at reciprocating compressors could reduce methane 

emissions by approximately 611,000 metric tons per year in 2018, one of the 

largest opportunities identified. 

Because many of these sources are located at the same facilities, including all of them 

within the scope of a comprehensive LDAR program entails minor incremental costs 

when compared to a conventional LDAR program with a more limited scope. At the 

same time, applying LDAR to this broader universe of sources has significant potential to 

identify additional leaks – especially malfunctioning equipment that contributes to a 

“gross emitter” profile – and thereby enhance the total cost-effectiveness of LDAR. 

Gas capture technologies can also be applied broadly. Two examples of this 

emerged in our review of the white papers. First, Reduced Emission Completion 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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technology, like leak detection technology, is used only for a discrete period of time and 

therefore can be applied across multiple facilities.

10 Second, gas capture technologies 

such as vapor recovery units and closed vent systems (which can re-route gas to 

compressor air intake or to a combustion device) can be applied to multiple sources of 

vented emissions at a facility. EPA’s discussion in the Compressor White Paper, for 

instance, evaluates the effectiveness of these technologies in mitigating rod-packing 

emissions, but the same technology can be applied to any source of vented emissions on 

the site (including open-ended lines, blow-down vent stacks, storage tanks, and many 

others). And, as EPA recognized, establishing connections between additional vented 

sources and capture technology involves minimal costs.11 

2. Synergistic Relationships

 

Beyond applying mitigation technologies broadly to all emissions sources, 

deploying these technologies in concert can actually enhance emission reduction benefits 

beyond those expected from the technologies on their own. In reviewing the White 

Papers, we found this to be the case where LDAR could be paired with equipment 

replacement practices. For instance, the Compressor White Paper evaluates the 

effectiveness of replacing reciprocating compressor rod packing at regular, three-year 

intervals. Because this rod packing wears out, emissions increase over time, and 

therefore regular replacement can help to reduce emissions (anywhere from 35 – 80 

percent based on data in the White Papers). This rate of wear, however, is an average 

across sources and particular compressors may wear out more swiftly or slowly 

depending on conditions. Accordingly, coupling LDAR with a rod-packing replacement 

program can help optimize timing of repairs and replacements. We believe LDAR could 

similarly help to optimize pneumatics replacement, as we discuss in our response to the 

Pneumatics White Paper. 

These synergistic relationships are not evaluated in the papers and we think they 

provide important additional benefits (and reductions in cost) that only further underscore 

the commonsense nature of these measures. 

3. Cost 

Some of the same cross-cutting features that enhance effectiveness likewise 

reduce costs, either in absolute terms or per-ton of pollutant abated. The most critical 

source of absolute cost reduction is monetary savings due to captured gas that would 

otherwise be wasted. In most cases, EPA’s White Papers evaluate these cost savings, 

which can have important impacts on overall costs. For instance, performing a reduced 

emission completion at many of the oil well completions measured in the UT study 

would completely recoup costs of the REC technology and result in a net cost savings to 

the operator. 

 

10 As EPA recognizes, this is also true of completion combustion devices. 

11 Compressor Paper at 35. 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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There are other economic benefits of emissions control technology, however, that 

EPA’s White Papers do not address. For example, owners of equipment in certain 

segments of the natural gas supply chain do not own the underlying natural gas and so do 

not realize monetary benefits on account of captured gas. As the ICF Report notes, 

however, this captured gas does have broader, economy-wide value which we urge EPA 

to consider as part of its evaluation of pollution control measures. ICF concluded that 

when those economy wide benefits are taken into account, the full suite of reduction 

strategies resulting in 40% emission reduction would actually generate roughly $150 

million in net annual savings.12 In addition, certain control measures, like using plunger 

lifts to mitigate liquids unloading emissions, result in captured gas but also enhance the 

productivity of the well.13 The benefits of enhanced production are identified in the ICF 

Report, but not in EPA’s White Papers, and we encourage the agency to consider these 

cost reducing factors as well. 

 Cost sharing is another important, cross-cutting consideration for evaluating 

costs. In particular, and in keeping with EPA’s emissions and mitigation analyses, the 

agency often attributes the entire cost of a pollution control measure to the specific source 

being evaluated. For example, EPA’s analysis of LDAR at well production sites in the 

2012 NSPS rulemaking assumed that each well site would require its own portable 

organic vapor analyzer. But this approach grossly overstates costs. As we discuss above, 

the same technology or practice – whether it be LDAR, RECs, or gas capture at 

compressors – can be applied to a number of different emissions points and can achieve 

multi-pollutant reductions. The costs of these pollution control measures should be 

evaluated accordingly, spreading them across emissions sources and pollutants in keeping 

with how they are applied in reality. 

Ultimately, as Part I concludes, each of the sources EPA identifies in the White 

Papers are significant and present important opportunities for reducing emissions. In 

addition to this discrete approach, however, a holistic view of the sources only 

underscores the significance of the emissions and the cost-effective nature of the 

mitigation measures EPA presents. 

III. CONTINUOUS IMPROVEMENT 

Parts I and II reflect the current landscape of emissions, mitigation technology 

and cost, and as we’ve described, provide a rigorous foundation for actions to address 

emissions from the oil and gas sector today. 

At the same time, the oil and gas industry is defined by continuous improvement 

in technology – a hallmark of how business proceeds in this competitive space. Consider 

that just in the last decade – as documented in the EDF Leaks response – innovation in 

infrared cameras has advanced the technology for leak detection, permitting swifter, often 

more comprehensive detection of leaks. Going forward, we urge EPA to ensure that 

 

12 ICF Cost Curve Report at 4-10. 

13 Id. at 3-18. 
ENVIRONMENTAL DEFENSE FUND • JUNE 16, 2014 

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actions based on today’s cost-effective technologies also incorporate flexibility to 

recognize and develop new advances in technology. 

Furthermore, policy making itself is expected to drive down compliance cost 

somewhat from where it is today by increasing production volumes and competition in 

the vendor market for detection and control technologies. In sum, today’s technology 

landscape provides a solid foundation for highly cost effective reductions, and if recent 

history and market fundamentals are a guide, deeper and expansive reductions will 

become even more cost-effective in the coming years as policy develops. 

IV. CONCLUSION 

EDF appreciates the effort and rigor that EPA has taken in preparing the White 

Papers, as well as the opportunity to provide expert review. We believe that the White 

Papers provide a sound technical foundation for further regulatory steps to reduce air 

pollution from the oil and gas sector, and are confident that the peer review process will 

only strengthen the knowledge base to inform effective action. 

We would welcome the chance to discuss our peer review responses with EPA 

staff. Please contact Ramón Alvarez on any matters relating to these comments. 

 Sincerely, 

Ramón Alvarez, Ph.D. 

Senior Scientist 

US Climate and Energy Program 

Environmental Defense Fund 

301 Congress Avenue, Suite #1300 

Austin, TX 78701 

512-691-3408 

ralvarez@edf.org