## Attachment X

Pneumatic Devices

Jim Bolander

Southwestern EnergyPeer

- review of “Report for Oil and Natural Gas Sector Pneumatic Devices”, April 2014, U.S. EPA Office of Air Quality Planning and Standards (OAQPS)

By Jim Bolander, P.E., Senior Vice President, Southwestern Energy (SWN)

I. General comments:

The Report for Oil and Natural Gas Sector Pneumatic Devices report (“White P aper ”) is a compendium of prior measurement s and analysis of methane emissions and control technologies related to gas driven pneumatic devices in the natural gas sector. The stated purpose of the white paper is to provide a “summary of the EPA’s understanding of

emission s from natural gas

- driven pneumatic controllers and pumps in the oil and natural gas sector, the mitigation techniques available to reduce these emissions, the efficacy of th ese techniques and prevalence of these techniques in the field.” In general, the summary developed in the White Paper is an accurate summary of the data contained in the

reference source but it is our recommend ation that EPA fully consider the

characteriz ation and limitations in these reports that lead up to the summary results that are reported . These comments reflect Southwestern Energy’s (SWN) collective thoughts on these sources with respect to emissions and mitigation opportunities. We

will not atte mpt to reiterate the summaries characterized in the White Paper. In

addition to the reference sources that EPA employs in the document, there are other

technical documents that we recommend the EPA consider in improving its understanding of the emissions profile and techniques from pneumatic devices

.

SWN believes that i t is important to separate out actual measurement studies from literature surveys and desktop analysis to understand the characterization and efficacy of pneumatic device s in operations. We recommend that EPA consider actual measured data, especially the more recent measurements

, to develop characterization of emission factors and policy options. There is an important new study underway led by Dr. David Allen with Univers ity of Texas to further evaluate and characterize methane emissions from pneumatic devices at upstream natural gas facilities (Phase II UT study) . This Phase II UT study is expected to be published in a peer

- reviewed journal by mid

- summer 2014. We strong ly urge the EPA to fully analyze this new Allen et al. paper in developing its policy recommendations.

The emissions estimation methods employed by the EPA and others rely on the emission factor and activity data. While there have been studies, including the ones referenced in this White Paper

, that have measured or analyzed the emission factors,

there ha s been very limited effort to address the equally important second part of the emissions equation

- i.e. the activity data

- how many pneumatic devices and pumps are operational in the industry ? T he activity data generation for EPA’s national emissionsinventory is an estimation which relies on seminal 1996 GRI/EPA report 1 for the activity data to essentially scale up the data i n subsequent reports. A total of 22 sites were used in the 1996 GRI/EPA report to establish a count of pneumatic devices for production sites and to determine the fraction of intermittent versus continuous bleed devices at each site. To this day, the EPA relies on the data collected at these 22 sites as the core basis for the activity data related to pneumatic devices.

We highly recommend that EPA revisit the activity data related to pneumatic devices in the natural gas industry and embark o n a more compr ehensive program employing both reports submitted by companies under the Subpart W 2 reporting program and field results to develop the appropriate activity data

.

The EPA estimated in the 2012 National Emissions Inventory (NEI) that emissions from pneumatic devices in the production sector were approximately 334 .4 giga grams (Gg) for the year 3

. This net estimate for pneumatic devices is derived by subtracting the imputed reductions from EPA Gas STAR program of 873.1 Gg 4 from the potential emissions of 1207.5 Gg 5 . The concern with this technique is that the methane reductions from the EPA Gas STAR program for 2012 do not match the reductions incorporated

into the NEI. W e understand the two different goals of the Gas STAR and NEI , but as long as EPA continues to rely on Gas STAR reductions in the NEI, it should make all attempts to ensure the data reported and extrapolated is reasonable. The EPA Gas

STAR reductions for 2012 are provided in F igure 1 showing the EPA estimate of abo ut 5.4 bcf of methane reductions or roughly 103 Gg 6 from pneumatic device s

. As explained by the EPA 7 , the main reason for this difference is because the EPA Gas STAR assumes a sunsetting period after 10 years of replacement of a technology (e.g. replacement of “high bleeds” with “low

- bleed” pneumatic devices) but the NEI assumes “perpetual credit” for such a replacement.

We have evaluated EPA’s indicated credits and have not been able to reconcile or reproduce the 873.1 Gg of methane emissions credited as part of the EPA Gas STAR reductions in the 2012 inventory.

1 Gas Research Institute (GRI)/U.S. Environmental Protection Agency. 1996c. Research and Development, Methane Emissions from the Natural Ga s Industry, Volume 12: Pneumatic Devices . June 1996. (EPA

- 600/R

- 96

- 080l). This report estimated 249,111± 48% pneum atic controllers in operations in 1992 based on the sum of the regional values of the ratio of number of devices per gas well and the number of devices per marketed gas production.

2 40 CFR Part 98, Subpart W

3 ANNEX 3 Methodological Descriptions for Addition al Source or Sink Categories Table A

- 141: Net

emissions for select sources

4 Table A

- 135: CH4 Reductions Derived from the Natural Gas STAR Program

5 Id, Table A

- 137: National CH4 Potential Emission Estimates from the Natural Gas Production Stage, and

Reduc tions from the Natural Gas STAR Program and Regulations

6 Conversion factor: One scf of methane contains 19.2 g methane

7 Personal correspondence with US EPAFigure 1: 2012 EPA Gas STAR Reductions from the Production Sector.

Using the 2012 activity data of 447,379 pneumatic devices and employing conservative assumptions that the mix of “intermittent” and “continuous” bleed devices are similar

to the 65%:35% ratio identified in the 1995 GRI/EPA report and assuming all continuous bleeds (regardless whether they are high or low bleed devices) are reduced
to a rate of 6 scfh, we estimate the total methane reductions would be about 560 Gg. This theoretical exercise demonstrates that EPA’s methods for estimating methane

emissions in the NEI are not reasonable

. Therefore, SWN recommends that the EPA conduct a comprehensive evaluation of the best available data to generate more

accurate activity data for pneumatic devices to inform its policy decisions.

Pneumatic devices are classified as an “unsteady source of emissions 8 ” and annual emissions were computed in the 1996 GRI/EPA report based on assessing emissions per event. As noted in the 1996 GRI/EPA report, “[f]ive sources of information were

used to determine the metha ne emissions from pneumatic devices used in the production segment” . These included measurements from 19 snap

- acting and 16 throttling controllers from “oil battery” facilities in Canada 9

8 ESTIMATE OF METHANE EMISSIONS FROM THE U.S. NATURAL GAS INDUSTRY David A. Kirchgessner , Robert A. Lott, R. Michael Cowgill, Matthew R. Harrison, Theresa M. Shires, C hemosphere, Vol. 35, No.6, pp. 1365

- 1390, 1997 Published by Elsevier Science Ltd , field measurements from Chevron and Tenneco which employed measurements using a flow meter and

emissions were “extrapolated” to a daily rate

. T he device count fraction from the 22

9 A Detailed Inventory of CH4 and VOC Emissions form Upstream Oil and Gas Operations in Alberta, D. J. Picard, B.D. Ross, and D.W.H.Koon, Clearstone Engineering Ltd, March 1992 for Canadian Petroleum

Associationsites (65% “non continuous bleed” and 35% “continuous bleed”) was used to sc ale the

associated emission factors from the sources above to generate “one emission factor for a “generic” pneumatic device 10

. The extrapolation of short term measurements to daily or annual estimates must be carefully analyzed in these studies, especiall y related to intermittent devices. These issues are further highlighted in the next section.

II. Methane Measurements

a. Characterization of methane emissions from Pneumatic devices

The white paper focuses on characterization of pneumatic devices by their emissions profile. As definitions are critical for policy and regulatory decisions, we would recommend the EPA to carefully consider the pneumatic characterizations in the 1996 GRI/EPA report 11

.

In addition, we emphasize the importance of time series cl assification. In general, intermittent bleed devices have a clear actuation pattern and returns to zero between actuations (i.e. stationary bleed rate equals 0). Continuous bleeds on the other hand

have a non

- zero bleed rate. We believe that classificat ion of continuous bleed devices into high

- bleed (>6 scfh 12 ) and low

- bleed (<6 scfh) are arbitrary and insufficient for policy development

. Instead, EPA should review emission profiles and understand their characteristics before developing appropriate policies

. The actuation frequency and the vent rate per actuation are important consideration s in assessing the emissions

characteristics of pneumatic devices. Pneumatic controllers have an actuating bleed rate (when the actuator is depressured) and a st ationary bleed rate, which can be zero for “snap

- acting” or intermittent devices. Various parameters can impact these bleed rates including device maintenance, supply gas pressure , actuating chamber size and type of manufacturer/design (as noted in the Pr asino Study 13 ).

It should be noted that there are no continuous emissions monitoring systems employed in any of the studies to measure methane emissions from pneumatic devices. Instead, measurement studies relied on measurement of the supply gas entering the pneumatic device using a flow meter or measureme nt of the gas actuated from controller using a Hi Flow sampler. The EPA should analyze all measurement studies, including the 1996 GRI/EPA study to assess whether the sample size and distribution is representative of current day operations; whether the me asurements had adequate sampling time to capture representative actuations; whether measurements covered all

10 Id. at Table 4

- 6, Methane Emission Factor for Average Device = 345 ± 40% scfd/device,

11 Table 3

- 1

12 6 scfh is roughly equal to 1 ton per year of methane.

13 The Prasino Group. 2013. Determining Bleed Rates for Pneumatic Devices in British Columbia; Final Report

. Prepared for the Science and Community Environmental Knowledge Fund. December 18, 2013. Available

at http://www.env.gov.bc.ca/cas/mitigation/ggrcta/reporting

regulation/pdf/Prasino_Pneumatic_GHG_EF_Final_Report.pdf.pneumatic devices or a sub

- set (e.g. pneumatic devices that were leaking as identified by an infra

- red camera or a random sample or just pneumatic devices over a certain bleed rates) and how the study author handled the devices that did not leak or were below the detection level of the instrument during the limited duration of the sampling. While most measurement studies measure emissions per actuat ion for a set sampling period, c are should be taken in extrapolating a short duration sample (say 15 minute) to an hourly or daily rate and EPA should carefully review the sampling data to

assess how the author handled the scale

- up and associated uncertain ty. The actuation frequency over the time period of interest (hourly or daily or annual) should be well understood and characterized. This can vary from one facility to the other and depends on the process being controlled. Simplistic extrapolation of s hort

- term measurements to an average hourly or daily or even annual methane rate quite often leads to incorrect

results.

In addition, regional differences and type of application are other important

characteristics that define the total annual emissions . As noted in the Allen et al 14 Phase I UT Study , there were s ignificant variations among regions, with the pneumatic devices in the Rocky Mountain regions exhibiting lower emission than devices in the Gulf Coast. In addition, the type of application of the controller may play an important role in total emissions and should be considered in all policy decisions. There are two main applications of these devices: a) control valves to regu late flow and b) isolation valves to isolate equipment and pipelines. As controllers, they are used in numerous devices such as separators, process heaters, compressors, dehydrators, flares etc. Isolation valves that are typically found at compressor and storage stations are used to isolate the facility in case of an emergency or if there are repairs or maintenance work to be carried out. Such type of pneumatics, including controllers employed in gas production sites on emergency devices actuate infreque ntly or in case of emergencies, but do emit large volumes when actuated and there is a potential that when averaged over an hour, these devices may emit greater than 6 scfh.

b. “Fat

- tails”: small number of sources are responsible for majority of the

emissi ons

Recent studies from Allen et al

. and from the Prasino Group have clearly indicated that a small fraction of the pneumatic controllers are responsible for a large portion of the

emissions.

Figure 2 provides the average emission rates from 305 devices measured as part of the Allen et al. Phase I study. In this study, a total of 25% (or 77 devices) had methane emissions greater than the study reported average of 0.175 scfm and about 40% of t he

14 Allen, David, T., et al. 2013. Measurements of methane emissions at natural gas production sites in the United

States. Proceedings of the National Academy of Sciences (PNAS)

. October 29, 2013. ( http://www.pnas.org/content/early/2013/09/10/1304880110.full.pdf+html ).devices emitted over 6 scfh. As noted in Figure 3, 80% of the emissions were from 27%

of the devices. The Prasino study reviewed 581 controllers and 184 pumps. Similarly the Prasino Study which 44% of devices with emissions greater than 6 scf/h accou nted

for 91% of emissions. In addition to results from “top

- down” studies 15

Hence, it is amply clear from actual measurement studies that a small fraction of the pneumatic devices or even facilities are responsible for a large portion of the emissions. Therefore, it is important to understand the regional differences, actuation

c haracteristics from the recent and upcoming methane studies. These studies will provide significant understanding of emissions profile from gas driven pneumatic

devices. , indicate the

same “fat

- tail” or super

- emitter phenomenon, though at a source level.

From a policy stand

- point, a “one

- size” approach to replacing such devices will not be appropriate. For e xample, a policy that requires replacement of such intermittent, infrequent controllers/valves with low

- bleed continuous devices emitting less than 6 scfh, even if operationally possible yields a negative environmental outcome since t he annual emissions from the controllers on emergency devices or isolation valves may be

much smaller than the low bleed continuous device. Hence, EPA should avoid adopting any “one

- size” policy with respect to mitigation technologies.

I. Other comments

a. Did this paper appropriately characterize the different studies and data sources that quantify emissions from pneumatic controllers and pneumatic pumps in the oil and gas sector?

We believe the paper appropriately characterizes the different studies and data sources. It is more important for EPA to fully understand the basis and inferences that can be drawn by the study findings. Just relying on the “central estimates” reported in the studies without fully understanding the basis for the estimates or contro l technologies reported may hinder the policy responses.

Figure 2: Pneumatic Measurements from Allen et al., 2013

15 See D. Caulton, et al., Toward a better understanding and quantification of methane emissions from shale gas development, April 14, 2014, doi: 10.1073/pnas. 1316546111, PNAS (April 14, 2014); A.R.
Brandt, et al. , Methane Leaks from North American Natural Gas Systems, Science, Vo. 343 ( Feb. 14, 2014);
G. Petron, et al. , A new look at methane and non

- methane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver

- Julesburg Basin, Journal of Geophysical Research: Atmospheres, doi: 10.1002/2013JD021272.Figure 3: Pneumatic Devices Emissions Profile (Allen et al., 2013)

a. Please discuss explanations for the wide range of emission rates that have been observed in direct measurement studies of pneumatic controller emissions (e.g., Allen et al., 2013 and Prasino 2013). Are these differences driven purely by the design of the m onitored controllers or are there operational characteristics, such as supply pressure, that play a crucial role in determining emissions? Avg, 0.175 scfm

0.000 0.500 1.000 1.500 2.000 2.500

0 50 100 150 200 250 300 350Measured Methane Emissions (scfm)

No of Devices Methane Emissions

Measured

Average Methane RateThis question has been addressed in the previous sections of this report. Yes, direct

measurement studies are clearly indicating a “fat

- tail” issue. In addition, there are regional variations and variations depending on the type of service. The actuation frequency

, the volume per actuation , controller design, supply pressure, maintenance practices are important parameters in determining the emissions.

b. Did this paper capture the full range of technologies available to reduce emissions from pneumatic controllers and pneumatic pumps oil and gas

facilities?

We emphasize that control technologies outlined in thi s report while theoretically correct does not address the key findings from the various direct measurement studies

and therefore we disagree with the summaries outlined below:

“Low bleed gas

- driven controllers can replace high bleed gas

- driven controllers in many, but not all, applications. ”

“ Where a reliable source of electrical power is available, instrument air systems can replace natural gas

- driven pneumatic controllers, and result in no methane

or VOC emissions. ”

“ Zero bleed, mechanical, and solar

- po wered controllers can replace continuous bleed controllers in certain applications, but are not broadly applicable to all segments of the oil and natural gas industry.”

First, these conclusions are rather simple and do not account for the fact that a vast majority of the pneumatic devices simply do not have “leakage” issue. There are “fat

tails” and appropriate smart policies have to be developed to address these issues. In actual operations, pneumatic controllers are called in response to demand s that a re not easily predictable in many cases. Hence, two similar controllers (same model and manufacturer) can have a totally different emissions profile depending on the location and operational characteristics of the process it supports . As noted in the Sim pson paper, intermittent devices typically offer the lowest emissions in most applications since there is no bleed between actuations, each application must be analyzed independently to consider local operational and safety considerations. Hence, a

mandat e to replace high bleeds with low or zero bleed via regulations or mandate replacement of intermittent devices with low or zero bleeds, may result in waste of capital and resources.

4. Please comment on the pros and cons of the different emission reductio n technologies. Please discuss efficacy, cost and feasibility for both new and existing pneumatics.See response to previous question.

9. Are there ongoing or planned studies that will substantially improve the current understanding of VOC and methane emissions from pneumatic controllers and pneumatic pumps and available techniques for increased product recovery and

emissions reductions?

1) Methane Emissions from Process Equipment at Natural Gas Production Sites in

the United States: Pneumatic Controllers, David Allen et al. ( to be published

2014)

2) Clearinghouse of Technological Options for Reducing Anthropogenic Non

- CO2 GHG Emissions from All Sectors, Jeff Kuo, Ph.D., P.E., Dept. of Civil and Environmental Engineering, California State University, Fullerton, Prepared for: State of

California Air Res ources Board Research Division. May 14, 2008