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Open Access
Appendices for "Characterization of methane emissions from gathering compressor stations: final report"
(Colorado State University. Libraries, 2019) Zimmerle, Daniel, author; Vaughn, Timothy, author; Luck, Benjamin, author; Lauderdale, Terri, author; Keen, Kindal, author; Harrison, Matthew, author; Marchese, Anthony, author; Williams, Laurie, author
This document is the appendices for the final report to the U.S. Department of Energy (DOE) for contract DE-FE0029068 awarded to Colorado State University (CSU). CSU and subcontractor AECOM partnered with nine U.S. midstream operators to characterize emissions from natural gas gathering and boosting stations ("gathering stations") - a sector of the natural gas supply chain where few measurements have been made and little data are available for component emissions. Although here is overlap in the classes of equipment on gathering stations with those on production sites or transmission stations that have been measured recently, emissions are likely to differ for functional and operational reasons. Partner companies provided the study team site access to (1) measure methane emissions and (2) collect activity data on equipment and operations. Field measurements were made at 180 facilities in 11 U.S. states during June-November 2017. Measured facilities were sampled from 1705 partner facilities located in 28 American Association of Petroleum Geologists (AAPG) basins. Measurements were made in basins representative of current U.S. production and facilities selected for measurement shared key characteristics in proportion to all partner facilities. The principal deliverable of this study is a set of emission factors for components and major equipment at gathering stations. Leaker and population emission factors were developed for components, and population factors were developed for major equipment. All data was also incorporated into a model to produce a nationally representative estimate of emissions from gathering stations. Emission factors and model results are intended to inform the U.S. Environmental Protection Agency (EPA) greenhouse gas inventory (GHGI). Components were counted on 1002 major equipment units (compressors, dehydrators, separators, tanks, acid gas removal units, and yard piping). Emission measurements were made on 1938 major equipment units. Data from a parallel study performed by GSI Environmental Inc. under the same DOE funding program were also incorporated. The field campaign supported a robust updating of emission factors for fugitive and vented emissions on components and major equipment. In general, the study indicates that study emission factors either agree with, or are larger than, current greenhouse gas reporting program (GHGRP) emission factors for the western U.S. and most GHGI emission factors, and are substantially larger than emission factors used by the GHGRP for the eastern U.S. This study also developed and field-tested two measurement methods to better characterize emissions from unburned methane entrained in compressor engine exhaust ("combustion slip") and vented and fugitive methane emissions from gas-powered, pneumatically actuated valves and controllers. Emissions from these sources are not well characterized at compressor stations. Long-term, direct measurements of pneumatic controller emissions were made on 72 pneumatic controllers (PCs) at 16 gathering stations; measurements averaged 76 hours in duration. New emission factors could not be developed due to measurement errors with the meters utilized for the study (see Section 4.3), and as a consequence, GHGRP emission factors were utilized to estimate pneumatic controller emissions in station and national estimates. However, the PC emissions data is still useful for a qualitative examination of pneumatic controller emissions [1]. In particular, these long-duration measurements provide insight into PC emissions behaviors that are not reflected in manufacturer's literature and have not been shown in prior studies. Recorded PC data shows a high degree of variability in operation over the course of hours or days - especially for intermittent vent PCs. Recordings also show an unexpectedly high occurrence of abnormal emission behavior - 25 of 40 intermittent vent controllers show abnormal behavior at some point during the recording, and 5 of 24 were emitting at higher than the low-bleed maximum of 6 scfh. Combustion slip was measured on 102 individual compressor drivers at 51 gathering stations. Results from combustion slip measurements indicate emissions similar to emission factors from EPA AP-42 [2]. Although component fugitive and vented emission factors are higher, current GHGI estimates are based upon whole-station measurements made in a prior field campaign [3] and subsequent national model [4]. Relative to these prior studies, and by extension the GHGI, emissions at stations measured during the field campaign are statistically lower. The current study drew a nationally-representative sample from a larger population of stations than the previous study (1705 stations versus 700 stations) while working with a larger group of industry partners (9 partners versus 4 partners), which raises confidence in the current study. While reasons cannot be definitively stated, likely causes of the lower methane emissions in this study are: (1) the previous study measured facilities with substantially higher throughput than the current study (39.5 [0.223 to 382] versus 19.7 [0.068 to 116] MMscfd whole gas); (2) the partner population in the previous study indicated a larger proportion of more complex stations {this study sampled 60% compression-only stations versus 30% in the previous study [3]; (3) the two studies utilized different measurement methods; and, (4) there may have been operational improvements to gathering stations during the intervening four years. To complete national estimates, the study utilized 319 per-basin GHGRP reports for gathering systems in 36 AAPG basins, including 15,895 reported compressors, and counts for other equipment, including gas pneumatic controllers, dehydrators, ares and other equipment. Using GHGRP activity data and data collected in the field campaign, the study estimated 6,108 [5,846 to 6,374] stations nationally, which is statistically higher then the current GHGI estimate of 5,241 stations. However, the study's national model indicated emissions that are statistically lower than current GHGI estimates for the gathering & boosting sector - 1,484 [1,439 to 1,537] Gg - y-1CH4 versus a GHGI estimate of 1,955.1 Gg - y-1CH4. Reasons for this difference align with those for station emission estimates - updated mix, size and throughput of stations, more complete activity data for stations, better estimates for unmeasured emission sources, including unit and station blowdowns, and possibly improvements in operations at gathering stations since prior studies. Results presented in this report are supported by several supplemental volumes which are cited throughout. Supplemental volumes are further supported by appendices, as cited within. In addition, results will be disseminated in three peer-reviewed publications currently in preparation.
Open Access
Characterization of methane emissions from gathering compressor stations: final report
(Colorado State University. Libraries, 2019) Zimmerle, Daniel, author; Bennett, Kristine, author; Vaughn, Timothy, author; Luck, Ben, author; Lauderdale, Terri, author; Keen, Kindal, author; Harrison, Matthew, author; Marchese, Anthony, author; Williams, Laurie, author; Allen, David, author
This document is the ﬁnal report to the U.S. Department of Energy (DOE) for contract DE-FE0029068 awarded to Colorado State University (CSU). CSU and subcontractor AECOM partnered with nine U.S. midstream operators to characterize emissions from natural gas gathering and boosting stations ("gathering stations") – a sector of the natural gas supply chain where few measurements have been made and little data are available for component emissions. Although there is overlap in the classes of equipment on gathering stations with those on production sites or transmission stations that have been measured recently, emissions are likely to diﬀer for functional and operational reasons. Partner companies provided the study team site access to (1) measure methane emissions and (2) collect activity data on equipment and operations. Field measurements were made at 180 facilities in 11 U.S. states during June-November 2017. Measured facilities were sampled from 1705 partner facilities located in 28 American Association of Petroleum Geologists (AAPG) basins. Measurements were made in basins representative of current U.S. production and facilities selected for measurement shared key characteristics in proportion to all partner facilities. The principal deliverable of this study is a set of emission factors for components and major equipment at gathering stations. Leaker and population emission factors were developed for components, and population factors were developed for major equipment. All data was also incorporated into a model to produce a nationally representative estimate of emissions from gathering stations. Emission factors and model results are intended to inform the U.S. Environmental Protection Agency (EPA) greenhouse gas inventory (GHGI). Components were counted on 1002 major equipment units (compressors, dehydrators, separators, tanks, acid gas removal units, and yard piping). Emission measurements were made on 1938 major equipment units. Data from a parallel study performed by GSI Environmental Inc. under the same DOE funding program were also incorporated. The ﬁeld campaign supported a robust updating of emission factors for fugitive and vented emissions on components and major equipment. In general, the study indicates that study emission factors either agree with, or are larger than, current greenhouse gas reporting program (GHGRP) emission factors for the western U.S. and most GHGI emission factors, and are substantially larger than emission factors used by the GHGRP for the eastern U.S. This study also developed and ﬁeld-tested two measurement methods to better characterize emissions from unburned methane entrained in compressor engine exhaust (“combustion slip”) and vented and fugitive methane emissions from gas-powered, pneumatically actuated valves and controllers. Emissions from these sources are not well characterized at compressor stations. Long-term, direct measurements of pneumatic controller emissions were made on 72 pneumatic controllers (PCs) at 16 gathering stations; measurements averaged 76 hours in duration. New emission factors could not be developed due to measurement errors with the meters utilized for the study (see Section 4.3), and as a consequence, GHGRP emission factors were utilized to estimate pneumatic controller emissions in station and national estimates. However, the PC emissions data is still useful for a qualitative examination of pneumatic controller emissions [1]. In particular, these long-duration measurements provide insight into PC emissions behaviors that are not reﬂected in manufacturer’s literature and have not been shown in prior studies. Recorded PC data shows a high degree of variability in operation over the course of hours or days – especially for intermittent vent PCs. Recordings also show an unexpectedly high occurrence of abnormal emission behavior – 25 of 40 intermittent vent controllers show abnormal behavior at some point during the recording, and 5 of 24 were emitting at higher than the low-bleed maximum of 6 scfh. Combustion slip was measured on 102 individual compressor drivers at 51 gathering stations. Results from combustion slip measurements indicate emissions similar to emission factors from EPA AP-42 [2]. Although component fugitive and vented emission factors are higher, current GHGI estimates are based upon whole-station measurements made in a prior ﬁeld campaign [3] and subsequent national model [4]. Relative to these prior studies, and by extension the GHGI, emissions at stations measured during the ﬁeld campaign are statistically lower. The current study drew a nationally-representative sample from a larger population of stations than the previous study (1705 stations versus ≈700 stations) while working with a larger group of industry partners (9 partners versus 4 partners), which raises conﬁdence in the current study. While reasons cannot be deﬁnitively stated, likely causes of the lower methane emissions in this study are: (1) the previous study measured facilities with substantially higher throughput than the current study (39.5 [0.223 to 382] versus 19.7 [0.068 to 116] MMscfd whole gas); (2) the partner population in the previous study indicated a larger proportion of more complex stations – this study sampled 60% compression-only stations versus 30% in the previous study [3]; (3) the two studies utilized diﬀerent measurement methods; and, (4) there may have been operational improvements to gathering stations during the intervening four years. To complete national estimates, the study utilized 319 per-basin GHGRP reports for gathering systems in 36 AAPG basins, including 15,895 reported compressors, and counts for other equipment, including gas pneumatic controllers, dehydrators, ﬂares and other equipment. Using GHGRP activity data and data collected in the ﬁeld campaign, the study estimated 6,108 [5,846 to 6,374] stations nationally, which is statistically higher then the current GHGI estimate of 5,241 stations. However, the study’s national model indicated emissions that are statistically lower than current GHGI estimates for the gathering & boosting sector – 1,484 [1,439 to 1,537] Gg · y−1CH4 versus a GHGI estimate of 1,955.1 Gg · y−1CH4. Reasons for this diﬀerence align with those for station emission estimates - updated mix, size and throughput of stations, more complete activity data for stations, better estimates for unmeasured emission sources, including unit and station blowdowns, and possibly improvements in operations at gathering stations since prior studies. Results presented in this report are supported by several supplemental volumes which are cited throughout. Supplemental volumes are further supported by appendices, as cited within. In addition, results will be disseminated in three peer-reviewed publications currently in preparation.
Open Access
Data associated with "Methane emissions from gathering and boosting compressor stations in the U.S. Supporting volume 1: Multi-day measurements of pneumatic controller emissions"
(Colorado State University. Libraries, 2019) Luck, Benjamin; Zimmerle, Daniel; Vaughn, Timothy; Lauderdale, Terri; Keen, Kindal; Harrison, Matthew; Marchese, Anthony; Williams, Laurie; Allen, David
This study was part of a larger study (the Gathering Emission Factor, or "GEF") study [1] to develop activity and methane emission factors for EPA's Greenhouse Gas Inventory (EPA GHGI) using direct emission measurements at the device level on all classes of equipment found on gathering compressor stations. To accomplish this, Colorado State University (CSU) partnered with the engineering firm AECOM to assist with planning, logistics, field work and analysis. Nine midstream natural gas companies – Anadarko Petroleum, Equinor, DCP Midstream, Kinder Morgan, MarkWest Energy Partners, Pioneer Natural Resources, Southwestern Energy, Williams Companies Inc., and XTO Energy Inc. – acted as partners in the study, provided site access for measurements, and provided representatives to advisory committees. At all times, and with the encouragement of industry partners, CSU maintained control the sampling plan, analysis and reporting. This study documents one part of the larger study - emissions from pneumatic actuated valve controllers (PC).
Open Access
Data associated with the manuscript: Investigating diesel engines as an atmospheric source of isocyanic acid in urban areas
(Colorado State University. Libraries, 2017) Jathar, Shantanu H.; Heppding, Christopher; Link, Michael F.; Farmer, Delphine K.; Akherati, Ali; Kleeman, Michael J.; de Gouw, Joost A.; Veres, Patrick R.; Roberts, James M.
Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urban environments and biomass burning-affected regions, has been linked to adverse health outcomes. Gasoline- and diesel-powered engines and biomass burning are known to emit HNCO and hypothesized to emit precursors such as amides that can photochemically react to produce HNCO in the atmosphere. Increasingly, diesel engines in developed countries like the United States are required to use Selective Catalytic Reduction (SCR) systems to reduce tailpipe emissions of oxides of nitrogen. SCR chemistry is known to produce HNCO as an intermediate product, and SCR systems have been implicated as an atmospheric source of HNCO. In this work, we measure HNCO emissions from an SCR system-equipped diesel engine and, in combination with earlier data, use a three-dimensional chemical transport model (CTM) to simulate the ambient concentrations and source/pathway contributions to HNCO in an urban environment. Engine tests were conducted at three different engine loads, using two different fuels and at multiple operating points. HNCO was measured using an acetate chemical ionization mass spectrometer. The diesel engine was found to emit primary HNCO (3-90 mg kg-fuel-1) but we did not find any evidence that the SCR system or other aftertreatment devices (i.e., oxidation catalyst and particle filter) produced or enhanced HNCO emissions. The CTM predictions compared well with the only available observational data sets for HNCO in urban areas but under-predicted the contribution from secondary processes. The comparison implied that diesel-powered engines were the largest source of HNCO in urban areas. The CTM also predicted that daily-averaged concentrations of HNCO reached a maximum of ~110 pptv but were an order of magnitude lower than the 1 ppbv level that could be associated with physiological effects in humans. Precursor contributions from other combustion sources (gasoline and biomass burning) and wintertime conditions could enhance HNCO concentrations but need to be explored in future work.
Open Access
Data associated with, "Methane emissions from gathering and boosting compressor stations in the U.S. Supporting volume 2: Compressor engine exhaust measurements
(Colorado State University. Libraries, 2019) Zimmerle, Daniel; Vaughn, Timothy; Luck, Ben; Lauderdale, Terri; Keen, Kindal; Harrison, Matt; Allen, David; Marchese, Anthony; Williams, Laurie
The in-stack tracer method was used during the field campaign to measure unburned methane entrained in the exhaust of natural gas compressor engines ("combustion slip"). Combustion slipwas estimated by injecting a tracer gas into the exhaust stream at a known flow-rate and measuring concentrations of both the tracer gas and methane at the exhaust stack exit. The total exhaustflow was estimated from the diluted tracer gas concentration measured at the exhaust stack exit.
Open Access
Data associated with, "Methane emissions from gathering and boosting compressor stations in the U.S.: Supporting volume 3: Emission factors, station estimates, and national emissions"
(Colorado State University. Libraries, 2019) Zimmerle, Daniel; Vaughn, Timothy; Luck, Ben; Lauderdale, Terri; Keen, Kindal; Harrison, Matthew; Marchese, Anthony; Williams, Laurie; Allen, David
This section provides an overview of the field campaign for the entire project and the data collected in the field campaign data and during the analysis phase of the project.
Open Access
Dataset associated with "A cautionary report of calculating methane emissions using low-cost fence-line sensors"
(Colorado State University. Libraries, 2022) Riddick, Stuart; Ancona, Riley
Methane is emitted during extraction, processing, and transport processes in the natural gas industry. As a powerful greenhouse gas, methane releases are harmful to the environment. Operators aim to minimize methane loss, and continuous monitoring using low-cost fence-line sensors are now being developed to observe methane enhancements downwind of operations. However, it is not clear how useful these systems are and whether they can be used to quantify emissions or simply identify the presence of a leak. To investigate this, we deployed four calibrated low-cost sensors 30 m from emissions of known rates over a 48-hour period. The aims were to determine: 1) how much of the time a fence-line system would detect a leakage event from a single, point source of the size typically seen at oil and gas production well pads; and 2) how accurately a fence-line system can estimate emissions using a relatively simple downwind dispersion method. Our results show that during the 48-hour measurement period the sensors could detect mixing ratios greater than an enhancement threshold of 2 ppm for methane releases of 84 g h-1 40% of the time, 100% of the time for emissions of 167 g h-1 and 100% of the time downwind of the 313 g h-1. We show that emissions can be overestimated by as much as 4 x 10102 times using a simple Gaussian plume equation, which was attributed to the inability of the equation to parameterize lateral dispersion at distances less than 100 m. Using two other methods, near real-time average emissions can be calculated to be within 23% of a known emission rate of the source, however individual emissions can vary by -100% and +1,885%. This study provides evidence to support the use of low-cost sensors as autonomous fence-line monitoring systems to detect and potentially quantify emissions. If the sensors are properly calibrated and sensor deployment location is optimized for prevailing wind directions at each site, fence-line systems could be used routinely to quantify emissions from oil and gas infrastructure.
Open Access
Dataset associated with "A laboratory assessment of 120 air pollutant emissions from biomass and fossil fuel cookstoves
(Colorado State University. Libraries, 2018) Bilsback, Kelsey
Cookstoves emit many pollutants that are harmful to human health and the environment. However, most of the existing scientific literature focuses on fine particulate matter (PM2.5) and carbon monoxide (CO). We present an extensive dataset of speciated air pollution emissions from wood, charcoal, kerosene, and liquefied petroleum gas (LPG) cookstoves. One-hundred and twenty gas- and particle-phase constituents—including organic carbon, elemental carbon (EC), ultrafine particles (10-100 nm), inorganic ions, carbohydrates, and volatile/semi-volatile organic compounds (e.g., alkanes, alkenes, alkynes, aromatics, carbonyls, and polycyclic aromatic hydrocarbons [PAHs])—were measured in the exhaust from 26 stove/fuel combinations. We find that improved biomass stoves tend to reduce PM2.5 emissions, however, certain design features (e.g., insulation or a fan) tend to increase relative levels of other co-emitted pollutants (e.g., EC, ultrafine particles, formaldehyde, or PAHs depending on stove type). In contrast, the pressurized kerosene and LPG stoves reduced all pollutants relative to a traditional three-stone fire (≥93% and ≥79%, respectively). Finally, we find that PM2.5 and CO are not strong predictors of co-emitted pollutants, which is problematic because these pollutants may not be indicators of other cookstove smoke constituents (such as formaldehyde and acetaldehyde) that may be emitted at concentrations that are harmful to human health.
Open Access
Dataset associated with "Temporal variability largely explains difference in top-down and bottom-up estimates of methane emissions from a natural gas production region"
(Colorado State University. Libraries, 2018) Vaughn, Timothy L.; Bell, Clay S.; Pickering, Cody, K.; Schwietzke, Stefan; Heath, Garvin, A.; Petron, Gabrielle; Zimmerle, Daniel; Schnell, Russell, C.; Nummedal, Dag
This study is the first to spatially and temporally align top-down and bottom-up methane emission estimates for a natural gas production basin, using multi-scale emission measurements and detailed activity data reporting. We show that episodic venting from manual liquid unloadings, which occur at a small fraction of natural gas well pads, drives a factor-of-two temporal variation in the basin-scale emission rate of a US dry shale gas play. The mid-afternoon peak emission rate aligns with the sampling time of all regional aircraft emission studies, which target well-mixed boundary layer conditions present in the afternoon. A mechanistic understanding of emission estimates derived from various methods is critical for unbiased emission verification and effective GHG emission mitigation. Our results demonstrate that direct comparison of emission estimates from methods covering widely different time scales can be misleading.
Open Access
MAES study sheet guide
(Colorado State University. Libraries, 2024-09-19) Mollel, Winrose, author; Mdigo, Jacob, author; Santos, Arthur, author; Vora, Prajay, author; Duggan, Jerry, author; Zimmerle, Daniel, author
This document provides definitions and instructions for completing Mechanistic Air Emissions Simulator (MAES) Study Sheets, one of the key input files required for running MAES. MAES is an updated version of the Methane Emission Estimation Tool (MEET). For details on additional input files, curated emissions data, and activity data, please refer to the main MAES documentation. The content addresses terms found in each tab and includes examples where applicable. Note that this document does not cover equipment operating states; for that information, consult the MAES help documentation at MEET2/README.html, then select ”MEET Model Reference” from the left-side menu.
Open Access
METEC controlled test protocol: continuous monitoring emission detection and quantification
(Colorado State University. Libraries, 2020-09-22) Bell, Clay, author; Zimmerle, Daniel, author
This testing will assess the performance of continuous monitoring (CM) systems which perform leak detection and quantification (LDAQ) under Single-Blind controlled release testing over a range of environmental conditions and emission rates. Testing will evaluate system-level performance measures including Probability of Detection and Detection Time. Additional metrics including accuracy and precision of localization and quantification estimates will be evaluated if applicable. Due to the dependence of methods on weather conditions, testing will require an extended period, typically months, with active emission and non-emissions periods to (1) allow each Experimental Design Point to operate for an extended duration, typically hours, and (2) assess performance across a wide range of meteorological conditions.
Open Access
METEC controlled test protocol: survey emission detection and quantification
(Colorado State University. Libraries, 2022-04-26) Bell, Clay, author; Zimmerle, Daniel, author
This testing will assess the performance of survey methods which perform leak detection and quantification (LDAQ) under single-blind controlled release testing over a range of environmental conditions and emission rates. Testing will evaluate system-level performance measures including Probability of Detection and Detection Time. Additional metrics including accuracy and precision of localization and quantification estimates will be evaluated if applicable.
Open Access
Methane emissions from gathering and boosting compressor stations in the U.S. Supporting volume 1: Multi-day measurements of pneumatic controller emissions
(Colorado State University. Libraries, 2019) Luck, Benjamin, author; Zimmerle, Daniel, author; Vaughn, Timothy, author; Lauderdale, Terri, author; Keen, Kindal, author; Harrison, Matthew, author; Marchese, Anthony, author; Williams, Laurie, author; Allen, Dave, author
This study was part of a larger study (the Gathering Emission Factor, or "GEF") study [1] to develop activity and methane emission factors for EPA's Greenhouse Gas Inventory (EPA GHGI) using direct emission measurements at the device level on all classes of equipment found on gathering compressor stations. To accomplish this, Colorado State University (CSU) partnered with the engineering firm AECOM to assist with planning, logistics, field work and analysis. Nine midstream natural gas companies – Anadarko Petroleum, Equinor, DCP Midstream, Kinder Morgan, MarkWest Energy Partners, Pioneer Natural Resources, Southwestern Energy, Williams Companies Inc., and XTO Energy Inc. – acted as partners in the study, provided site access for measurements, and provided representatives to advisory committees. At all times, and with the encouragement of industry partners, CSU maintained control the sampling plan, analysis and reporting. This study documents one part of the larger study - emissions from pneumatic actuated valve controllers (PC).
Open Access
Methane emissions from gathering and boosting compressor stations in the U.S. Supporting volume 2: Compressor engine exhaust measurements
(Colorado State University. Libraries, 2019) Vaughn, Timothy, author; Luck, Benjamin, author; Zimmerle, Daniel, author; Marchese, Anthony, author; Williams, Laurie, author; Keen, Kindal, author; Lauderdale, Terri, author; Harrison, Matthew, author; Allen, David, author
The in-stack tracer method was used during the field campaign to measure unburned methane entrained in the exhaust of natural gas compressor engines ("combustion slip"). Combustion slip was estimated by injecting a tracer gas into the exhaust stream at a known flow-rate and measuring concentrations of both the tracer gas and methane at the exhaust stack exit. The total exhaust flow was estimated from the diluted tracer gas concentration measured at the exhaust stack exit.
Open Access
Methane emissions from gathering and boosting compressor stations in the U.S. Supporting volume 3: Emission factors, station estimates, and national emissions
(Colorado State University. Libraries, 2019) Zimmerle, Daniel, author; Vaughn, Timothy, author; Luck, Benjamin, author; Lauderdale, Terri, author; Keen, Kindal, author; Harrison, Matthew, author; Marchese, Anthony, author; Williams, Laurie, author; Allen, David, author
This section provides an overview of the field campaign for the entire project and the data collected in the field campaign data and during the analysis phase of the project.
Open Access
Mid-continent basin - methane emissions reconciliation: facility level emissions
(Colorado State University. Libraries, 2016-05-26) Zimmerle, Dan, author
Summary of results methane emission reconciliation for facility-level emissions using several measurement techniques during a comprehensive measurement campaign in a mid-continent basin. Comparison of bottom up versus top down methodologies.
Open Access
Mid-continent methane emissions study
(Colorado State University. Libraries, 2016) Zimmerle, Daniel; Howell, Cynthia; Nummedal, Dag; Smits, Kathleen
In this first-of-its-kind Mid-Continent Methane Emissions Study, researchers from across the region, universities, government agencies, and industries joined forces determined to reconcile discrepancies between measurement methods in methane loss rates from onshore oil and gas developments in multiple basins. Seeking to bring public and private sectors better understanding of this issue, the combined resources of these groups resulted in weeks of field study and conclusive data. This team discovered that in other studies, top-down measurements reported much higher methane leak rates than bottom-up methods. Equipped with that knowledge this team used paired measurements from the same natural gas sources to determine the inconsistencies in measurement methods. The result of a field campaign, which happened over a five week period from late September to early October, 2015 is described in the study overview.
Open Access
Open-source high flow sampler for natural gas leak quantification
(Colorado State University. Libraries, 2022-04-14) Zimmerle, Daniel, author; Vaughn, Timothy, author; Bennett, Kristine, author; Ross, Cody, author; Harrison, Matthew, author; Wilson, Aaron, author; Johnson, Chris, author
Open Access
Quantifying proximity, confinement, and interventions in disease outbreaks: a decision support framework for air-transported pathogens
(Colorado State University. Libraries, 2021-02-19) Bond, Tami C, author; Bosco-Lauth, Angela, author; Farmer, Delphine K., author; Francisco, Paul W., author; Pierce, Jeﬀrey R., author; Fedak, Kristen M., author; Ham, Jay M., author; Jathar, Shantanu H., author; VandeWoude, Sue, author; Environmental Science & Technology, publisher
The inability to communicate how infectious diseases are transmitted in human environments has triggered avoidance of interactions during the COVID-19 pandemic. We define a metric, Effective ReBreathed Volume (ERBV), that encapsulates how infectious pathogens, including SARS-CoV-2, transport in air. ERBV separates environmental transport from other factors in the chain of infection, allowing quantitative comparisons among situations. Particle size affects transport, removal onto surfaces, and elimination by mitigation measures, so ERBV is presented for a range of exhaled particle diameters: 1, 10, and 100 μm. Pathogen transport depends on both proximity and confinement. If interpersonal distancing of 2 m is maintained, then confinement, not proximity, dominates rebreathing after 10–15 min in enclosed spaces for all but 100 μm particles. We analyze strategies to reduce this confinement effect. Ventilation and filtration reduce person-to-person transport of 1 μm particles (ERBV1) by 13–85% in residential and office situations. Deposition to surfaces competes with intentional removal for 10 and 100 μm particles, so the same interventions reduce ERBV10 by only 3–50%, and ERBV100 is unaffected. Prior knowledge of size-dependent ERBV would help identify transmission modes and effective interventions. This framework supports mitigation decisions in emerging situations, even before other infectious parameters are known.

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