1
|
Zimmerle D, Dileep S, Quinn C. Unaddressed Uncertainties When Scaling Regional Aircraft Emission Surveys to Basin Emission Estimates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6575-6585. [PMID: 38564483 PMCID: PMC11025109 DOI: 10.1021/acs.est.3c08972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/04/2024]
Abstract
Wide-area aerial methods provide comprehensive screening of methane emissions from oil and gas (O & G) facilities in production basins. Emission detections ("plumes") from these studies are also frequently scaled to the basin level, but little is known regarding the uncertainties during scaling. This study analyzed an aircraft field study in the Denver-Julesburg basin to quantify how often plumes identified maintenance events, using a geospatial inventory of 12,629 O & G facilities. Study partners (7 midstream and production operators) provided the timing and location of 5910 maintenance events during the 6 week study period. Results indicated three substantial uncertainties with potential bias that were unaddressed in prior studies. First, plumes often detect maintenance events, which are large, short-duration, and poorly estimated by aircraft methods: 9.2 to 46% (38 to 52%) of plumes on production were likely known maintenance events. Second, plumes on midstream facilities were both infrequent and unpredictable, calling into question whether these estimates were representative of midstream emissions. Finally, 4 plumes attributed to O & G (19% of emissions detected by aircraft) were not aligned with any O & G location, indicating that the emissions had drifted downwind of some source. It is unclear how accurately aircraft methods estimate this type of plume; in this study, it had material impact on emission estimates. While aircraft surveys remain a powerful tool for identifying methane emissions on O & G facilities, this study indicates that additional data inputs, e.g., detailed GIS data, a more nuanced analysis of emission persistence and frequency, and improved sampling strategies are required to accurately scale plume estimates to basin emissions.
Collapse
Affiliation(s)
- Daniel Zimmerle
- Energy
Institute, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Sonu Dileep
- Department
of Computer Science, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Casey Quinn
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80524, United States
| |
Collapse
|
2
|
Sun S, Ma L, Li Z. Methane emission and influencing factors of China's oil and natural gas sector in 2020-2060: A source level analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167116. [PMID: 37722430 DOI: 10.1016/j.scitotenv.2023.167116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 08/03/2023] [Accepted: 09/14/2023] [Indexed: 09/20/2023]
Abstract
The Chinese oil and gas industry requires targeted policies to reduce methane emissions. To achieve this goal, it is necessary to predict future methane emission trends and analyze the factors that influence them. However, changing economic development patterns, insufficient analysis of various factors influencing emissions, and inadequate resolution of methane emission inventories have made these goals difficult to achieve. Accordingly, this study aims to expand the methane emission estimation method to compile source-level emission inventories for future emissions, analyze the factors influencing them, and form a mechanistic understanding of the methane emissions from the local oil and gas industry. The research results indicate that methane emissions deriving from this industry will increase rapidly before 2030, after which they will decline slowly in all scenarios. The production and utilization processes in the natural gas supply chain, i.e., compressors and liquid unloading, include the main sources of methane emissions. Emissions are affected significantly by total production and consumption. Change in the overall supply and demand of natural gas affects change in methane emissions more significantly than adopting new technologies and strengthening facility maintenance, i.e., the overall supply and demand of natural gas are the dominant factors in controlling methane emissions. This study suggests that controlling the total demand for oil and gas should be at the core of the methane emission control policy for the local oil and gas industry. Moreover, equipment maintenance and emission reduction technologies should be used more effectively to reduce total emissions.
Collapse
Affiliation(s)
- Shuo Sun
- State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua-BP Clean Energy Research and Education Centre, Tsinghua University, Beijing 100084, China.
| | - Linwei Ma
- State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua-BP Clean Energy Research and Education Centre, Tsinghua University, Beijing 100084, China.
| | - Zheng Li
- State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua-BP Clean Energy Research and Education Centre, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
3
|
Bell C, Ilonze C, Duggan A, Zimmerle D. Performance of Continuous Emission Monitoring Solutions under a Single-Blind Controlled Testing Protocol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5794-5805. [PMID: 36977200 PMCID: PMC10100557 DOI: 10.1021/acs.est.2c09235] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 06/18/2023]
Abstract
Continuous emission monitoring (CM) solutions promise to detect large fugitive methane emissions in natural gas infrastructure sooner than traditional leak surveys, and quantification by CM solutions has been proposed as the foundation of measurement-based inventories. This study performed single-blind testing at a controlled release facility (release from 0.4 to 6400 g CH4/h) replicating conditions that were challenging, but less complex than typical field conditions. Eleven solutions were tested, including point sensor networks and scanning/imaging solutions. Results indicated a 90% probability of detection (POD) of 3-30 kg CH4/h; 6 of 11 solutions achieved a POD < 6 kg CH4/h, although uncertainty was high. Four had true positive rates > 50%. False positive rates ranged from 0 to 79%. Six solutions estimated emission rates. For a release rate of 0.1-1 kg/h, the solutions' mean relative errors ranged from -44% to +586% with single estimates between -97% and +2077%, and 4 solutions' upper uncertainty exceeding +900%. Above 1 kg/h, mean relative error was -40% to +93%, with two solutions within ±20%, and single-estimate relative errors were from -82% to +448%. The large variability in performance between CM solutions, coupled with highly uncertain detection, detection limit, and quantification results, indicates that the performance of individual CM solutions should be well understood before relying on results for internal emissions mitigation programs or regulatory reporting.
Collapse
Affiliation(s)
- Clay Bell
- Energy
Institute, Colorado State University, Fort Collins, Colorado 80524, United States
- BPX
Energy, Denver, Colorado 80202, United
States
| | - Chiemezie Ilonze
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Aidan Duggan
- Energy
Institute, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Daniel Zimmerle
- Energy
Institute, Colorado State University, Fort Collins, Colorado 80524, United States
| |
Collapse
|
4
|
Allen DT, Cardoso-Saldaña FJ, Kimura Y, Chen Q, Xiang Z, Zimmerle D, Bell C, Lute C, Duggan J, Harrison M. A Methane Emission Estimation Tool (MEET) for predictions of emissions from upstream oil and gas well sites with fine scale temporal and spatial resolution: Model structure and applications. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 829:154277. [PMID: 35276157 DOI: 10.1016/j.scitotenv.2022.154277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/27/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
In comparing observation based methane emission estimates for oil and gas well sites to routine emissions reported in inventories, the time scale of the measurement should match the time scale over which the inventoried emissions are estimated. Since many measurements are of relatively short duration (seconds to hours), a tool is needed to estimate emissions over these time scales rather than the annual totals reported in most emission inventories. This work presents a tool for estimating routine emissions from oil and gas well sites at multiple time scales; emissions at well sites vary over time due to changes in oil and gas production rates, operating practices and operational modes at the sites. Distributions of routine emissions (expected and inventoried) from well sites are generally skewed, and the nature and degree to which the distributions are skewed depends on the time scales over which emissions are aggregated. Abnormal emissions can create additional skew in these distributions. At very short time scales (emissions aggregated over 1 min) case study distributions presented in this work are both skewed and bimodal, with the modes depending on whether liquid storage tanks are flashing at the time of the measurement and whether abnormal emissions are occurring. At longer time scales (emissions aggregated over 1 day) distributions of routine emissions simulated in this work can have multiple modes if short duration, high emission rate events, such as liquid unloadings or large abnormal emissions, occur at the site. Multiple applications of the methane emission estimation tool (MEET), developed in this work, are presented. These results emphasize the importance of developing detailed emission inventories, which incorporate operational data, when comparing measurements to routine emissions. The model described in this work supports such comparisons and is freely available.
Collapse
Affiliation(s)
- David T Allen
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA.
| | - Felipe J Cardoso-Saldaña
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
| | - Yosuke Kimura
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
| | - Qining Chen
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
| | - Zhanhong Xiang
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
| | - Daniel Zimmerle
- Energy Institute, Colorado State University, Fort Collins, CO, USA
| | - Clay Bell
- Energy Institute, Colorado State University, Fort Collins, CO, USA
| | - Chris Lute
- Energy Institute, Colorado State University, Fort Collins, CO, USA
| | - Jerry Duggan
- Energy Institute, Colorado State University, Fort Collins, CO, USA
| | - Matthew Harrison
- SLR International, 22118 20th Ave SE, Suite G202, Bothell, WA 98021, USA
| |
Collapse
|
5
|
Tavakkoli S, Feng L, Miller SM, Jordaan SM. Implications of Generation Efficiencies and Supply Chain Leaks for the Life Cycle Greenhouse Gas Emissions of Natural Gas-Fired Electricity in the United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:2540-2550. [PMID: 35107984 DOI: 10.1021/acs.est.1c05246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Uncertainties in supply chain emissions raise questions about the benefits of natural gas as a bridge fuel, but recent efficiency improvements in gas-fired electricity generation remain overlooked. Our comprehensive analysis of supply chain infrastructure and electricity generation across the United States informs spatially and temporally resolved estimates of life cycle greenhouse gas emissions. Results show decreasing life cycle emissions over each year examined: 629, 574, and 525 kg CO2 eq MWh-1 in 2005, 2010, and 2015, respectively. Electricity generation contributed 86% of emissions or greater for each year. Despite concerns over uncertain methane leaks, efficiency improvements make it much more likely that natural gas electricity has an unambiguous greenhouse gas benefit relative to coal. Methane leaks would have to be 4.4 times the Environmental Protection Agency (EPA) value in 2015 to reverse these benefits over 20-year time horizons. With retiring coal plants and scrutinized supply chain emissions, our results show that natural gas can provide a lower emissions option to coal in an increasingly decarbonized power sector.
Collapse
Affiliation(s)
- Sakineh Tavakkoli
- School of Advanced International Studies, Johns Hopkins University, 1619 Massachusetts Ave NW, Washington, District of Columbia 20036, United States
| | - Leyang Feng
- Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Scot M Miller
- Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Sarah M Jordaan
- School of Advanced International Studies, Johns Hopkins University, 1619 Massachusetts Ave NW, Washington, District of Columbia 20036, United States
- Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| |
Collapse
|
6
|
Gao J, Guan C, Zhang B. Why are methane emissions from China's oil & natural gas systems still unclear? A review of current bottom-up inventories. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 807:151076. [PMID: 34678371 DOI: 10.1016/j.scitotenv.2021.151076] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/06/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
There is growing awareness and concern on methane (CH4) emissions from China's oil and natural gas (ONG) systems owing to the carbon neutral target. This paper aims to present a comprehensive review on the bottom-up inventories of the CH4 emissions from the perspective of the ONG systems in China. The trend and magnitude of total emissions in the last four decades were revealed and limitations of current estimations were explored. Previous studies showed that the average CH4 emissions from China's ONG systems have almost tripled from 1980 (760 Gg) to 2015 (2180 Gg) with a trend of steady increase. However, the estimated values varied by an order-of-magnitude with the largest discrepancy of 2700 Gg. This discrepancy was unlikely caused mainly by the incompleteness of estimation, since dominant emission sources were all covered by representative studies. Moreover, the differences of activity-level data were within ±10%, which ruled out the possibility that it was the main contributor to the large discrepancies. The emissions estimate has huge variation in large part because of differences in assumed emission factors (EFs) that vary by an order of magnitude. The difficulty was to determine which of the EFs were accurate due to measurement-based data availability. Thus, the large discrepancies stem from the scarcity of publicly available data, which enlarged the impact from various methods adopted by previous studies. For better understanding of CH4 emissions from the ONG systems in China, the measurements of facility-level emissions and statistics on the ONG infrastructure are required urgently. Due to the high cost and experience-oriented measurement work, international cooperation and communications are critical prerequisites for future CH4 emission estimates and effective mitigation strategies.
Collapse
Affiliation(s)
- Junlian Gao
- School of Management, China University of Mining & Technology (Beijing), Beijing 100083, PR China
| | - ChengHe Guan
- New York University Shanghai, Shanghai 200122, PR China; Harvard China Project, School of Engineering and Applied Sciences, Harvard University, MA 02138, United States
| | - Bo Zhang
- School of Management, China University of Mining & Technology (Beijing), Beijing 100083, PR China; Harvard China Project, School of Engineering and Applied Sciences, Harvard University, MA 02138, United States; State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology (Beijing), Beijing 100083, PR China.
| |
Collapse
|
7
|
Lin JC, Bares R, Fasoli B, Garcia M, Crosman E, Lyman S. Declining methane emissions and steady, high leakage rates observed over multiple years in a western US oil/gas production basin. Sci Rep 2021; 11:22291. [PMID: 34785727 PMCID: PMC8595340 DOI: 10.1038/s41598-021-01721-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 10/26/2021] [Indexed: 11/22/2022] Open
Abstract
Methane, a potent greenhouse gas, is the main component of natural gas. Previous research has identified considerable methane emissions associated with oil and gas production, but estimates of emission trends have been inconsistent, in part due to limited in-situ methane observations spanning multiple years in oil/gas production regions. Here we present a unique analysis of one of the longest-running datasets of in-situ methane observations from an oil/gas production region in Utah’s Uinta Basin. The observations indicate Uinta methane emissions approximately halved between 2015 and 2020, along with declining gas production. As a percentage of gas production, however, emissions remained steady over the same years, at ~ 6–8%, among the highest in the U.S. Addressing methane leaks and recovering more of the economically valuable natural gas is critical, as the U.S. seeks to address climate change through aggressive greenhouse emission reductions.
Collapse
Affiliation(s)
- John C Lin
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, USA.
| | - Ryan Bares
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, USA.,Division of Air Quality, Utah Department of Environmental Quality, Salt Lake City, USA.,Division of Air Quality, Utah Department of Environmental Quality, Salt Lake City, USA
| | - Benjamin Fasoli
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, USA
| | - Maria Garcia
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, USA
| | - Erik Crosman
- Department of Life, Earth and Environmental Sciences, West Texas A&M University, Canyon, USA
| | - Seth Lyman
- Bingham Research Center, Utah State University, Salt Lake City, USA
| |
Collapse
|
8
|
Rutherford JS, Sherwin ED, Ravikumar AP, Heath GA, Englander J, Cooley D, Lyon D, Omara M, Langfitt Q, Brandt AR. Closing the methane gap in US oil and natural gas production emissions inventories. Nat Commun 2021; 12:4715. [PMID: 34354066 PMCID: PMC8342509 DOI: 10.1038/s41467-021-25017-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/27/2021] [Indexed: 11/09/2022] Open
Abstract
Methane (CH4) emissions from oil and natural gas (O&NG) systems are an important contributor to greenhouse gas emissions. In the United States, recent synthesis studies of field measurements of CH4 emissions at different spatial scales are ~1.5-2× greater compared to official greenhouse gas inventory (GHGI) estimates, with the production-segment as the dominant contributor to this divergence. Based on an updated synthesis of measurements from component-level field studies, we develop a new inventory-based model for CH4 emissions, for the production-segment only, that agrees within error with recent syntheses of site-level field studies and allows for isolation of equipment-level contributions. We find that unintentional emissions from liquid storage tanks and other equipment leaks are the largest contributors to divergence with the GHGI. If our proposed method were adopted in the United States and other jurisdictions, inventory estimates could better guide CH4 mitigation policy priorities.
Collapse
Affiliation(s)
- Jeffrey S Rutherford
- Department of Energy Resources Engineering, Stanford University, Stanford, CA, USA
| | - Evan D Sherwin
- Department of Energy Resources Engineering, Stanford University, Stanford, CA, USA
| | - Arvind P Ravikumar
- Department of Systems Engineering, Harrisburg University of Science and Technology, Harrisburg, PA, USA
| | - Garvin A Heath
- Joint Institute for Strategic Energy Analysis (JISEA), National Renewable Energy Laboratory, Golden, CO, USA
| | - Jacob Englander
- Industrial Strategies Division, California Air Resources Board, Sacramento, CA, USA
| | - Daniel Cooley
- Department of Statistics, Colorado State University, Ft. Collins, CO, USA
| | - David Lyon
- Environmental Defense Fund, Austin, TX, USA
| | - Mark Omara
- Environmental Defense Fund, Austin, TX, USA
| | - Quinn Langfitt
- Industrial Strategies Division, California Air Resources Board, Sacramento, CA, USA
| | - Adam R Brandt
- Department of Energy Resources Engineering, Stanford University, Stanford, CA, USA.
| |
Collapse
|
9
|
Liu RE, Ravikumar AP, Bi XT, Zhang S, Nie Y, Brandt A, Bergerson JA. Greenhouse Gas Emissions of Western Canadian Natural Gas: Proposed Emissions Tracking for Life Cycle Modeling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9711-9720. [PMID: 34254796 DOI: 10.1021/acs.est.0c06353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Natural gas (NG) produced in Western Canada is a major and growing source of Canada's energy and greenhouse gas (GHG) emissions portfolio. Despite recent progress, there is still only limited understanding of the sources and drivers of Western Canadian greenhouse gas (GHG) emissions. We conduct a case study of a production facility based on Seven Generation Energy Ltd.'s Western Canadian operations and an upstream NG emissions intensity model. The case study upstream emissions intensity is estimated to be 3.1-4.0 gCO2e/MJ NG compared to current best estimates of British Columbia (BC) emissions intensities of 6.2-12 gCO2e/MJ NG and a US average estimate of 15 gCO2e/MJ. The analysis reveals that compared to US studies, public GHG emissions data for Western Canada is insufficient as current public data satisfies only 50% of typical LCA model inputs. Company provided data closes most of these gaps (∼80% of the model inputs). We recommend more detailed data collection and presentation of government reported data such as a breakdown of vented and fugitive methane emissions by source. We propose a data collection template to facilitate improved GHG emissions intensity estimates and insight about potential mitigation strategies.
Collapse
Affiliation(s)
- Ryan E Liu
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Arvind P Ravikumar
- Department of Systems Engineering, Harrisburg University of Science and Technology, Harrisburg, Pennsylvania 17101, United States
| | - Xiaotao Tony Bi
- Department of Chemical Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
- Department of Energy Resources Engineering, Stanford University, Stanford, California 94305, United States
| | - Siduo Zhang
- Department of Chemical Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Yuhao Nie
- Department of Energy Resources Engineering, Stanford University, Stanford, California 94305, United States
| | - Adam Brandt
- Department of Energy Resources Engineering, Stanford University, Stanford, California 94305, United States
| | - Joule A Bergerson
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| |
Collapse
|
10
|
Johnson D, Heltzel R. On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site. ACS OMEGA 2021; 6:14200-14207. [PMID: 34124443 PMCID: PMC8190792 DOI: 10.1021/acsomega.1c00874] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/14/2021] [Indexed: 06/12/2023]
Abstract
Understanding methane emissions from the natural gas supply chain continues to be of interest. Previous studies identified that measurements are skewed due to "super-emitters", and recently, researchers identified temporal variability as another contributor to discrepancies among studies. We focused on the latter by performing 17 methane audits at a single production site over 4 years, from 2016 to 2020. Source detection was similar to Method 21 but augmented with accurate methane mass rate quantification. Audit results varied from ∼78 g/h to over 43 kg/h with a mean emissions rate of 4.2 kg/h and a geometric mean of 821 g/h. Such high variability sheds light that even quarterly measurement programs will likely yield highly variable results. Total emissions were typically dominated by those from the produced water storage tank. Of 213 sources quantified, a single tank measurement represented 60% of the cumulative emission rate. Measurements were separated into four categories: wellheads (n = 78), tank (n = 17), enclosed gas process units (n = 31), and others (n = 97). Each subgroup of measurements was skewed and fat-tailed, with the skewness ranging from 2.4 to 5.7 and kurtosis values ranging from 6.5 to 33.7. Analyses found no significant correlations between methane emissions and temperature, whole gas production, or water production. Since measurement results were highly variable and daily production values were known, we completed a Monte Carlo analysis to estimate average throughput-normalized methane emissions which yielded an estimate of 0.093 ± 0.013%.
Collapse
|
11
|
Hildenbrand ZL, Schug KA. Reservoir optimized plunger lift technology reduces hydrocarbon emissions from aging gas wells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 759:143475. [PMID: 33208255 DOI: 10.1016/j.scitotenv.2020.143475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/14/2020] [Accepted: 10/26/2020] [Indexed: 06/11/2023]
Abstract
Gas well liquification is a problematic process whereby liquids collect in the wellbore and near wellbore reservoir resulting in production impedance in aging gas wells. Removal of these liquids is traditionally performed through human operated blowdown events; however, this practice results in the release of hydrocarbon emissions into the atmosphere. The removal process, called 'deliquification', can also be accomplished through the utilization of various plunger lift technologies. These allow the extraction of retained fluids from the wellbore and near-wellbore reservoir; however, these technologies vary greatly with respect to automation, intelligence, and efficacy. Here we examined the rates of production loss and the frequency of emission events in mature natural gas wells equipped with various automated plunger lift technologies. Overall, 'intelligent' plunger lift systems that base their optimization on reservoir and wellbore conditions, as opposed to standardized or scheduled operations, performed the best exhibiting a 0.13% loss of production gas to atmospheric emissions compared to a 1.37% loss of production observed from wells without a plunger lift system. Additionally, wells equipped with a next generation reservoir optimized plunger lift demonstrated a reduced rate of production decline compared to those wells without a plunger lift technology (-0.066%/day and -0.242%/day, respectively). These data have widespread implications for the operational and environmental management of a consistently increasing count of aging natural gas production wells.
Collapse
Affiliation(s)
- Zacariah L Hildenbrand
- Collaborative Laboratories for Environmental Analysis and Remediation, The University of Texas at Arlington, Arlington, TX 76019, United States of America; Inform Environmental, LLC, Dallas, TX 75206, United States of America; Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, TX 79968, United States of America.
| | - Kevin A Schug
- Collaborative Laboratories for Environmental Analysis and Remediation, The University of Texas at Arlington, Arlington, TX 76019, United States of America; Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, United States of America
| |
Collapse
|
12
|
Cardoso-Saldaña FJ, Allen DT. Projecting the Temporal Evolution of Methane Emissions from Oil and Gas Production Basins. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:2811-2819. [PMID: 33587606 DOI: 10.1021/acs.est.0c04224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The methane emission intensity (methane emitted/gas produced or methane emitted/methane produced) of individual unconventional oil and gas production sites in the United States has a characteristic temporal behavior, exhibiting a brief period of decrease followed by a steady increase, with intensities after 10 years of production reaching levels that are 2-10 times the 10 year production-weighted average. Temporal patterns for methane emission intensity for entire production regions are more complex. Historical production data and facility data were used with a detailed basin-wide methane emission model to simulate the collective behavior of tens of thousands of wells and associated midstream facilities. For production regions with few to no new wells being brought to production, and existing wells having reached a mature stage, as in the Barnett Shale production region in north central Texas, the methane emission intensity gradually increases, as natural gas production decreases faster than emissions decrease, following the general pattern exhibited by individual wells. In production regions that are rapidly evolving, either with large numbers of new wells being put into production or with the introduction of source-specific regulations, the behavior is more complex. In the Eagle Ford Shale, which has had both a large number of new wells and the introduction of source-specific regulations, the methane emission intensity stays within relatively narrow bounds but the distribution of sources varies. As source distributions vary, basin-wide propane-to-methane and ethane-to-methane emission ratios vary, impacting methods used in source attribution.
Collapse
Affiliation(s)
- Felipe J Cardoso-Saldaña
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnett Road, Austin, Texas 78758, United States
- ExxonMobil Upstream Integrated Solutions, Spring, Texas 77389, United States
| | - David T Allen
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnett Road, Austin, Texas 78758, United States
| |
Collapse
|
13
|
Shaw JT, Allen G, Pitt J, Shah A, Wilde S, Stamford L, Fan Z, Ricketts H, Williams PI, Bateson P, Barker P, Purvis R, Lowry D, Fisher R, France J, Coleman M, Lewis AC, Risk DA, Ward RS. Methane flux from flowback operations at a shale gas site. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2020; 70:1324-1339. [PMID: 32915694 DOI: 10.1080/10962247.2020.1811800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/10/2020] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
We report measurements of methane (CH4) mixing ratios and emission fluxes derived from sampling at a monitoring station at an exploratory shale gas extraction facility in Lancashire, England. Elevated ambient CH4 mixing ratios were recorded in January 2019 during a period of cold-venting associated with a nitrogen lift process at the facility. These processes are used to clear the well to stimulate flow of natural gas from the target shale. Estimates of CH4 flux during the emission event were made using three independent modeling approaches: Gaussian plume dispersion (following both a simple Gaussian plume inversion and the US EPA OTM 33-A method), and a Lagrangian stochastic transport model (WindTrax). The three methods yielded an estimated peak CH4 flux during January 2019 of approximately 70 g s-1. The total mass of CH4 emitted during the six-day venting period was calculated to be 2.9, 4.2 ± 1.4(1σ) and 7.1 ± 2.1(1σ) tonnes CH4 using the simple Gaussian plume model, WindTrax, and OTM-33A methods, respectively. Whilst the flux approaches all agreed within 1σ uncertainty, an estimate of 4.2 (± 1.4) tonnes CH4 represents the most confident assessment due to the explicit modeling of advection and meteorological stability permitted using the WindTrax model. This mass is consistent with fluxes calculated by the Environment Agency (in the range 2.7 to 6.8 tonnes CH4), using emission data provided by the shale site operator to the regulator. This study provides the first CH4 emission estimate for a nitrogen lift process and the first-reported flux monitoring of a UK shale gas site, and contributes to the evaluation of the environmental impacts of shale gas operations worldwide. This study also provides forward guidance on future monitoring applications and flux calculation in transient emission events. Implications: This manuscript discusses atmospheric measurements near to the UK's first hydraulic fracturing facility, which has very high UK public, media, and policy interest. The focus of this manuscript is on a single week of data in which a large venting event at the shale gas site saw emissions of ~4 tonnes of methane to atmosphere, in breach of environmental permits. These results are likely to beresults are likely to be reported by the media and may influence future policy decisions concerning the UK hydraulic fracturing industry.
Collapse
Affiliation(s)
- Jacob T Shaw
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Grant Allen
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Joseph Pitt
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Adil Shah
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Shona Wilde
- Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York , Heslington, UK
| | - Laurence Stamford
- Department of Chemical Engineering and Analytical Science, University of Manchester , Manchester, UK
| | - Zhaoyang Fan
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Hugo Ricketts
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
- National Centre for Atmospheric Science, University of Manchester , Manchester, UK
| | - Paul I Williams
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
- National Centre for Atmospheric Science, University of Manchester , Manchester, UK
| | - Prudence Bateson
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Patrick Barker
- Centre for Atmospheric Science, Department of Earth and Environmental Science, University of Manchester , Manchester, UK
| | - Ruth Purvis
- National Centre for Atmospheric Science, University of York , Heslington, UK
| | - David Lowry
- School of Earth Sciences, Royal Holloway University of London , Egham, UK
| | - Rebecca Fisher
- School of Earth Sciences, Royal Holloway University of London , Egham, UK
| | - James France
- School of Earth Sciences, Royal Holloway University of London , Egham, UK
- British Antarctic Survey, Natural Environment Research Council , Cambridge, UK
| | - Max Coleman
- School of Earth Sciences, Royal Holloway University of London , Egham, UK
| | - Alastair C Lewis
- National Centre for Atmospheric Science, University of York , Heslington, UK
| | - David A Risk
- Department of Earth Sciences, St. Francis Xavier University , Antigonish, Nova Scotia, Canada
| | - Robert S Ward
- British Geological Survey, Environmental Science Centre , Nottingham, UK
| |
Collapse
|
14
|
Cardoso-Saldaña FJ, Allen DT. Projecting the Temporal Evolution of Methane Emissions from Oil and Gas Production Sites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14172-14181. [PMID: 33108865 DOI: 10.1021/acs.est.0c03049] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Many recent studies have reported methane emissions from oil and gas production regions, often reporting results as a methane emission intensity (methane emitted as a percentage of natural gas produced or methane produced). Almost all of these studies have been instantaneous snapshots of methane emissions; however, total methane emissions from a production site and the methane emission intensity would be expected to evolve over time. A detailed site-level methane emission estimation model is used to estimate the temporal evolution of methane emissions and the methane emission intensity for a variety of well configurations with and without emission mitigation measures in place. The general pattern predicted is that total emissions decrease over time as production declines. Methane emission intensity shows complex behavior because production-dependent emissions decline at different rates and some emissions do not decline over time. Prototypical uncontrolled wet gas wells can have approximately half of their emissions over a 10 year period occur in the first year; instantaneous wellsite methane emission intensities range over a factor of 3 (0.62-2.00%) in the same period, with a 10 year production weighted-average lifecycle methane emission intensity of 0.79%. Including emission control in the form of a flare can decrease the average lifecycle methane emission intensity to 0.23%. Emissions from liquid unloadings, which are observed in subsets of wells, can increase the lifecycle methane emission intensity by up to a factor of 2-3, between 1.2 and 2.3%, depending on the characteristics of the unloadings. Emissions from well completion flowbacks raise the average lifecycle methane emission intensity from 0.79 to 0.81% for flowbacks with emission controls; for flowbacks with uncontrolled emissions, lifecycle methane emissions increase to 1.26%. Dry gas and oil wells show qualitatively similar temporal behavior but different absolute emission rates.
Collapse
Affiliation(s)
- Felipe J Cardoso-Saldaña
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnett Road, Austin, Texas 78758, United States
- ExxonMobil Upstream Integrated Solutions, Spring, Texas 77389, United States
| | - David T Allen
- Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnett Road, Austin, Texas 78758, United States
| |
Collapse
|
15
|
Abstract
This study evaluates a new generation of satellite imaging spectrometers to measure point source methane emissions from anthropogenic sources. We used the Airborne Visible and Infrared Imaging Spectrometer Next Generation(AVIRIS-NG) images with known methane plumes to create two simulated satellite products. One simulation had a 30 m spatial resolution with ~200 Signal-to-Noise Ratio (SNR) in the Shortwave Infrared (SWIR) and the other had a 60 m spatial resolution with ~400 SNR in the SWIR; both products had a 7.5 nm spectral spacing. We applied a linear matched filter with a sparsity prior and an albedo correction to detect and quantify the methane emission in the original AVIRIS-NG images and in both satellite simulations. We also calculated an emission flux for all images. We found that all methane plumes were detectable in all satellite simulations. The flux calculations for the simulated satellite images correlated well with the calculated flux for the original AVIRIS-NG images. We also found that coarsening spatial resolution had the largest impact on the sensitivity of the results. These results suggest that methane detection and quantification of point sources will be possible with the next generation of satellite imaging spectrometers.
Collapse
|
16
|
Crow DJG, Balcombe P, Brandon N, Hawkes AD. Assessing the impact of future greenhouse gas emissions from natural gas production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:1242-1258. [PMID: 31018464 DOI: 10.1016/j.scitotenv.2019.03.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/04/2019] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
Greenhouse gases (GHGs) produced by the extraction of natural gas are an important contributor to lifecycle emissions and account for a significant fraction of anthropogenic methane emissions in the USA. The timing as well as the magnitude of these emissions matters, as the short term climate warming impact of methane is up to 120 times that of CO2. This study uses estimates of CO2 and methane emissions associated with different upstream operations to build a deterministic model of GHG emissions from conventional and unconventional gas fields as a function of time. By combining these emissions with a dynamic, techno-economic model of gas supply we assess their potential impact on the value of different types of project and identify stranded resources in various carbon price scenarios. We focus in particular on the effects of different emission metrics for methane, using the global warming potential (GWP) and the global temperature potential (GTP), with both fixed 20-year and 100-year CO2-equivalent values and in a time-dependent way based on a target year for climate stabilisation. We report a strong time dependence of emissions over the lifecycle of a typical field, and find that bringing forward the stabilisation year dramatically increases the importance of the methane contribution to these emissions. Using a commercial database of the remaining reserves of individual projects, we use our model to quantify future emissions resulting from the extraction of current US non-associated reserves. A carbon price of at least 400 USD/tonne CO2 is effective in reducing cumulative GHGs by 30-60%, indicating that decarbonising the upstream component of the natural gas supply chain is achievable using carbon prices similar to those needed to decarbonise the energy system as a whole. Surprisingly, for large carbon prices, the choice of emission metric does not have a significant impact on cumulative emissions.
Collapse
Affiliation(s)
- Daniel J G Crow
- Sustainable Gas Institute, Imperial College London, London SW7 2AZ, UK.
| | - Paul Balcombe
- Sustainable Gas Institute, Imperial College London, London SW7 2AZ, UK; Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Nigel Brandon
- Sustainable Gas Institute, Imperial College London, London SW7 2AZ, UK
| | - Adam D Hawkes
- Sustainable Gas Institute, Imperial College London, London SW7 2AZ, UK; Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
17
|
Cardoso-Saldaña FJ, Kimura Y, Stanley P, McGaughey G, Herndon SC, Roscioli JR, Yacovitch TI, Allen DT. Use of Light Alkane Fingerprints in Attributing Emissions from Oil and Gas Production. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5483-5492. [PMID: 30912428 DOI: 10.1021/acs.est.8b05828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Spatially resolved emission inventories were used with an atmospheric dispersion model to predict ambient concentrations of methane, ethane, and propane in the Eagle Ford oil and gas production region in south central Texas; predicted concentrations were compared to ground level observations. Using a base case inventory, predicted median propane/ethane concentration ratios were 106% higher (95% CI: 83% higher-226% higher) than observations, while median ethane/methane concentration ratios were 112% higher (95% CI: 17% higher-228% higher) than observations. Predicted median propane and ethane concentrations were factors of 6.9 (95% CI: 3-15.2) and 3.4 (95% CI: 1.4-9) larger than observations, respectively. Predicted median methane concentrations were 7% higher (95% CI: 39% lower-37% higher) than observations. These comparisons indicate that sources of emissions with high propane/ethane ratios (condensate tank flashing) were likely overestimated in the inventories. Because sources of propane and ethane emissions are also sources of methane emissions, the results also suggest that sources of emissions with low ethane/methane ratios (midstream sources) were underestimated. This analysis demonstrates the value of using multiple light alkanes in attributing sources of methane emissions and evaluating the performance of methane emission inventories for oil and natural gas production regions.
Collapse
Affiliation(s)
- Felipe J Cardoso-Saldaña
- Center for Energy and Environmental Resources , University of Texas at Austin , 10100 Burnet Road , Austin , Texas 78758 , United States
| | - Yosuke Kimura
- Center for Energy and Environmental Resources , University of Texas at Austin , 10100 Burnet Road , Austin , Texas 78758 , United States
| | - Peter Stanley
- Center for Energy and Environmental Resources , University of Texas at Austin , 10100 Burnet Road , Austin , Texas 78758 , United States
- Now at ONEOK , Tulsa , Oklahoma 74103 United States
| | - Gary McGaughey
- Center for Energy and Environmental Resources , University of Texas at Austin , 10100 Burnet Road , Austin , Texas 78758 , United States
| | - Scott C Herndon
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 United States
| | - Joseph R Roscioli
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 United States
| | - Tara I Yacovitch
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 United States
| | - David T Allen
- Center for Energy and Environmental Resources , University of Texas at Austin , 10100 Burnet Road , Austin , Texas 78758 , United States
| |
Collapse
|
18
|
Zaimes GG, Littlefield JA, Augustine DJ, Cooney G, Schwietzke S, George FC, Lauderdale T, Skone TJ. Characterizing Regional Methane Emissions from Natural Gas Liquid Unloading. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4619-4629. [PMID: 30924643 DOI: 10.1021/acs.est.8b05546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A "bottom-up" probabilistic model was developed using engineering first-principles to quantify annualized throughput normalized methane emissions (TNME) from natural gas liquid unloading activities for 18 basins in the United States in 2016. For each basin, six discrete liquid-unloading scenarios are considered, consisting of combinations of well types (conventional and unconventional) and liquid-unloading systems (nonplunger, manual plunger lift, and automatic plunger lift). Analysis reveals that methane emissions from liquids unloading are highly variable, with mean TNMEs ranging from 0.0093% to 0.38% across basins. Automatic plunger-lift systems are found to have significantly higher per-well methane emissions rates relative to manual plunger-lift or non-plunger systems and on average constitute 28% of annual methane emissions from liquids unloading over all basins despite representing only ∼0.43% of total natural gas well count. While previous work has advocated that operational malfunctions and abnormal process conditions explain the existence of super-emitters in the natural gas supply chain, this work finds that super-emitters can arise naturally due to variability in underlying component processes. Additionally, average cumulative methane emissions from liquids unloading, attributed to the natural gas supply chain, across all basins are ∼4.8 times higher than those inferred from the 2016 Greenhouse Gas Reporting Program (GHGRP). Our new model highlights the importance of technological disaggregation, uncertainty quantification, and regionalization in estimating episodic methane emissions from liquids unloading. These insights can help reconcile discrepancies between "top-down" (regional or atmospheric studies) and "bottom-up" (component or facility-level) studies.
Collapse
Affiliation(s)
- George G Zaimes
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - James A Littlefield
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Daniel J Augustine
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Gregory Cooney
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Stefan Schwietzke
- NOAA Earth System Research Laboratory , 325 Broadway , Boulder , Colorado 80305 , United States
- Cooperative Institute for Research in Environmental Sciences , University of Colorado , 216 UCB , Boulder , Colorado 80309 , United States
| | - Fiji C George
- Cheniere Energy, Inc. , 700 Milam Street, Suite 1900 , Houston , Texas 77002 United States
| | - Terri Lauderdale
- AECOM , 9400 Amberglen Boulevard , Austin , Texas 78729 , United States
| | - Timothy J Skone
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| |
Collapse
|
19
|
Pollution Tradeoffs for Conventional and Natural Gas-Based Marine Fuels. SUSTAINABILITY 2019. [DOI: 10.3390/su11082235] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper presents a life-cycle emissions analysis of conventional and natural gas-based marine transportation in the United States. We apply a total fuel cycle—or “well-to-propeller”—analysis that evaluates emissions along the fuel production and delivery pathway, including feedstock extraction, processing, distribution, and use. We compare emissions profiles for methanol, liquefied natural gas, and low sulfur marine fuel in our analysis, with a focus on exploring tradeoffs across the following pollutants: greenhouse gases, particulate matter, sulfur oxides, and nitrogen oxides. For our greenhouse gas analysis, we apply global warming potentials that consider both near-term (20-year) and long-term (100-year) climate forcing impacts. We also conduct uncertainty analysis to evaluate the impacts of methane leakage within the natural gas recovery, processing, and distribution stages of its fuel cycle. Our results indicate that natural-gas based marine fuels can provide significant local environmental benefits compared to distillate fuel; however, these benefits come with a near-term—and possibly long-term—global warming penalty, unless such natural gas-based fuels are derived from renewable feedstock, such as biomass. These results point to the importance of controlling for methane leaks along the natural gas production process and the important role that renewable natural gas can play in the shipping sector. Decision-makers can use these results to inform decisions related to increasing the use of alternative fuels in short sea and coast-wise marine transportation systems.
Collapse
|
20
|
Alden CB, Coburn SC, Wright RJ, Baumann E, Cossel K, Perez E, Hoenig E, Prasad K, Coddington I, Rieker GB. Single-Blind Quantification of Natural Gas Leaks from 1 km Distance Using Frequency Combs. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2908-2917. [PMID: 30695644 DOI: 10.1021/acs.est.8b06259] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A new method is tested in a single-blind study for detection, attribution, and quantification of methane emissions from the natural gas supply chain, which contribute substantially to annual U.S. emissions. The monitoring approach couples atmospheric methane concentration measurements from an open-path dual frequency comb laser spectrometer with meteorological data in an inversion to characterize emissions. During single-blind testing, the spectrometer is placed >1 km from decommissioned natural gas equipment configured with intentional leaks of controllable rate. Single, steady emissions ranging from 0 to 10.7 g min-1 (0-34.7 scfh) are detected, located, and quantified at three gas pads of varying size and complexity. The system detects 100% of leaks, including leaks as small as 0.96 g min-1 (3.1 scfh). It attributes leaks to the correct pad or equipment group (tank battery, separator battery, wellhead battery) 100% of the time and to the correct equipment (specific separator, tank, or wellhead) 67% of the time. All leaks are quantified to within 3.7 g min-1 (12 scfh); 94% are quantified to within 2.8 g min-1 (9 scfh). These tests are an important initial demonstration of the methodology's viability for continuous monitoring of large regions, with extension to other trace gases and industries.
Collapse
Affiliation(s)
| | | | | | - Esther Baumann
- National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Kevin Cossel
- National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Edgar Perez
- National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Eli Hoenig
- National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | - Kuldeep Prasad
- National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Ian Coddington
- National Institute of Standards and Technology , Boulder , Colorado 80305 , United States
| | | |
Collapse
|
21
|
Mac Kinnon M, Heydarzadeh Z, Doan Q, Ngo C, Reed J, Brouwer J. Need for a marginal methodology in assessing natural gas system methane emissions in response to incremental consumption. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2018; 68:1139-1147. [PMID: 29771631 DOI: 10.1080/10962247.2018.1476274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/01/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
Accurate quantification of methane emissions from the natural gas system is important for establishing greenhouse gas inventories and understanding cause and effect for reducing emissions. Current carbon intensity methods generally assume methane emissions are proportional to gas throughput so that increases in gas consumption yield linear increases in emitted methane. However, emissions sources are diverse and many are not proportional to throughput. Insights into the causal drivers of system methane emissions, and how system-wide changes affect such drivers are required. The development of a novel cause-based methodology to assess marginal methane emissions per unit of fuel consumed is introduced. Implications: The carbon intensities of technologies consuming natural gas are critical metrics currently used in policy decisions for reaching environmental goals. For example, the low-carbon fuel standard in California uses carbon intensity to determine incentives provided. Current methods generally assume methane emissions from the natural gas system are completely proportional to throughput. The proposed cause-based marginal emissions method will provide a better understanding of the actual drivers of emissions to support development of more effective mitigation measures. Additionally, increasing the accuracy of carbon intensity calculations supports the development of policies that can maximize the environmental benefits of alternative fuels, including reducing greenhouse gas emissions.
Collapse
Affiliation(s)
- Michael Mac Kinnon
- a Advanced Power and Energy Program , University of California , Irvine , CA
| | - Zahra Heydarzadeh
- a Advanced Power and Energy Program , University of California , Irvine , CA
| | - Quy Doan
- b Southern California Gas Company , Los Angeles , CA , USA
| | - Cuong Ngo
- b Southern California Gas Company , Los Angeles , CA , USA
| | - Jeff Reed
- b Southern California Gas Company , Los Angeles , CA , USA
| | - Jacob Brouwer
- a Advanced Power and Energy Program , University of California , Irvine , CA
| |
Collapse
|
22
|
Temporal variability largely explains top-down/bottom-up difference in methane emission estimates from a natural gas production region. Proc Natl Acad Sci U S A 2018; 115:11712-11717. [PMID: 30373838 PMCID: PMC6243284 DOI: 10.1073/pnas.1805687115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Our results demonstrate that access to high-resolution spatiotemporal activity data and multiscale, contemporaneous measurements is critical to understanding oil- and gas-related methane emissions. Careful consideration of all factors influencing methane emissions—including temporal variation—is necessary in scientific and policy discussions to develop effective strategies for mitigating greenhouse gas emissions from natural gas infrastructure. This study spatially and temporally aligns top-down and bottom-up methane emission estimates for a natural gas production basin, using multiscale 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 midafternoon 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 greenhouse gas emission mitigation. Our results demonstrate that direct comparison of emission estimates from methods covering widely different timescales can be misleading.
Collapse
|
23
|
Alvarez RA, Zavala-Araiza D, Lyon DR, Allen DT, Barkley ZR, Brandt AR, Davis KJ, Herndon SC, Jacob DJ, Karion A, Kort EA, Lamb BK, Lauvaux T, Maasakkers JD, Marchese AJ, Omara M, Pacala SW, Peischl J, Robinson AL, Shepson PB, Sweeney C, Townsend-Small A, Wofsy SC, Hamburg SP. Assessment of methane emissions from the U.S. oil and gas supply chain. Science 2018; 361:186-188. [PMID: 29930092 DOI: 10.1126/science.aar7204] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/18/2018] [Indexed: 11/02/2022]
Abstract
Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. Environmental Protection Agency inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Substantial emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Anna Karion
- National Institute of Standards and Technology, Gaithersburg, MD, USA
| | | | | | - Thomas Lauvaux
- The Pennsylvania State University, University Park, PA, USA
| | | | | | - Mark Omara
- Environmental Defense Fund, Austin, TX, USA
| | | | - Jeff Peischl
- University of Colorado, CIRES, Boulder, CO, USA.,NOAA Earth System Research Laboratory, Boulder, CO, USA
| | | | | | - Colm Sweeney
- NOAA Earth System Research Laboratory, Boulder, CO, USA
| | | | | | | |
Collapse
|
24
|
Bolorinos J, Ajami NK, Muñoz Meléndez G, Jackson RB. Evaluating Environmental Governance along Cross-Border Electricity Supply Chains with Policy-Informed Life Cycle Assessment: The California-Mexico Energy Exchange. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5048-5061. [PMID: 29630347 DOI: 10.1021/acs.est.7b06580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This paper presents a "policy-informed" life cycle assessment of a cross-border electricity supply chain that links the impact of each unit process to its governing policy framework. An assessment method is developed and applied to the California-Mexico energy exchange as a unique case study. CO2-equivalent emissions impacts, water withdrawals, and air quality impacts associated with California's imports of electricity from Mexican combined-cycle facilities fueled by natural gas from the U.S. Southwest are estimated, and U.S. and Mexican state and federal environmental regulations are examined to assess well-to-wire consistency of energy policies. Results indicate most of the water withdrawn per kWh exported to California occurs in Baja California, most of the air quality impacts accrue in the U.S. Southwest, and emissions of CO2-equivalents are more evenly divided between the two regions. California energy policy design addresses generation-phase CO2 emissions, but not upstream CO2-eq emissions of methane during the fuel cycle. Water and air quality impacts are not regulated consistently due to varying U.S. state policies and a lack of stringent federal regulation of unconventional gas development. Considering local impacts and the regulatory context where they occur provides essential qualitative information for functional-unit-based measures of life cycle impact and is necessary for a more complete environmental impact assessment.
Collapse
Affiliation(s)
- Jose Bolorinos
- Department of Civil and Environmental Engineering , Stanford University , 473 Via Ortega , Stanford , California 94305 , United States
| | - Newsha K Ajami
- Woods Institute for the Environment , Stanford University , 473 Via Ortega , Stanford , California 94305 , United States
- Bill Lane Center for the American West , Stanford University , 473 Via Ortega Room 173 , Stanford , California 94305 , United States
| | - Gabriela Muñoz Meléndez
- Bill Lane Center for the American West , Stanford University , 473 Via Ortega Room 173 , Stanford , California 94305 , United States
- Departamento de Estudios Urbanos y del Medio Ambiente , El Colegio de la Frontera Norte , A.C. Km 18.5 Carretera Escénica Tijuana - Ensenada San Antonio del Mar Tijuana , Baja California 22560 , Mexico
| | - Robert B Jackson
- Woods Institute for the Environment , Stanford University , 473 Via Ortega , Stanford , California 94305 , United States
- Department of Earth System Science and Precourt Institute for Energy , Stanford University , Stanford , California 94305 , United States
| |
Collapse
|
25
|
Bolden AL, Schultz K, Pelch KE, Kwiatkowski CF. Exploring the endocrine activity of air pollutants associated with unconventional oil and gas extraction. Environ Health 2018; 17:26. [PMID: 29558955 PMCID: PMC5861625 DOI: 10.1186/s12940-018-0368-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 02/20/2018] [Indexed: 05/17/2023]
Abstract
BACKGROUND In the last decade unconventional oil and gas (UOG) extraction has rapidly proliferated throughout the United States (US) and the world. This occurred largely because of the development of directional drilling and hydraulic fracturing which allows access to fossil fuels from geologic formations that were previously not cost effective to pursue. This process is known to use greater than 1,000 chemicals such as solvents, surfactants, detergents, and biocides. In addition, a complex mixture of chemicals, including heavy metals, naturally-occurring radioactive chemicals, and organic compounds are released from the formations and can enter air and water. Compounds associated with UOG activity have been linked to adverse reproductive and developmental outcomes in humans and laboratory animal models, which is possibly due to the presence of endocrine active chemicals. METHODS Using systematic methods, electronic searches of PubMed and Web of Science were conducted to identify studies that measured chemicals in air near sites of UOG activity. Records were screened by title and abstract, relevant articles then underwent full text review, and data were extracted from the studies. A list of chemicals detected near UOG sites was generated. Then, the potential endocrine activity of the most frequently detected chemicals was explored via searches of literature from PubMed. RESULTS Evaluation of 48 studies that sampled air near sites of UOG activity identified 106 chemicals detected in two or more studies. Ethane, benzene and n-pentane were the top three most frequently detected. Twenty-one chemicals have been shown to have endocrine activity including estrogenic and androgenic activity and the ability to alter steroidogenesis. Literature also suggested that some of the air pollutants may affect reproduction, development, and neurophysiological function, all endpoints which can be modulated by hormones. These chemicals included aromatics (i.e., benzene, toluene, ethylbenzene, and xylene), several polycyclic aromatic hydrocarbons, and mercury. CONCLUSION These results provide a basis for prioritizing future primary studies regarding the endocrine disrupting properties of UOG air pollutants, including exposure research in wildlife and humans. Further, we recommend systematic reviews of the health impacts of exposure to specific chemicals, and comprehensive environmental sampling of a broader array of chemicals.
Collapse
Affiliation(s)
- Ashley L. Bolden
- The Endocrine Disruption Exchange (TEDX), www.TEDX.org, Eckert, Colorado USA
| | - Kim Schultz
- The Endocrine Disruption Exchange (TEDX), www.TEDX.org, Eckert, Colorado USA
| | - Katherine E. Pelch
- The Endocrine Disruption Exchange (TEDX), www.TEDX.org, Eckert, Colorado USA
| | - Carol F. Kwiatkowski
- The Endocrine Disruption Exchange (TEDX), www.TEDX.org, Eckert, Colorado USA
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado USA
- Biological Sciences, North Carolina State University, Raleigh, North Carolina USA
| |
Collapse
|
26
|
Johnson MR, Tyner DR, Conley S, Schwietzke S, Zavala-Araiza D. Comparisons of Airborne Measurements and Inventory Estimates of Methane Emissions in the Alberta Upstream Oil and Gas Sector. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13008-13017. [PMID: 29039181 DOI: 10.1021/acs.est.7b03525] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Airborne measurements of methane emissions from oil and gas infrastructure were completed over two regions of Alberta, Canada. These top-down measurements were directly compared with region-specific bottom-up inventories that utilized current industry-reported flaring and venting volumes (reported data) and quantitative estimates of unreported venting and fugitive sources. For the 50 × 50 km measurement region near Red Deer, characterized by natural gas and light oil production, measured methane fluxes were more than 17 times greater than that derived from directly reported data but consistent with our region-specific bottom-up inventory-based estimate. For the 60 × 60 km measurement region near Lloydminster, characterized by significant cold heavy oil production with sand (CHOPS), airborne measured methane fluxes were five times greater than directly reported emissions from venting and flaring and four times greater than our region-specific bottom up inventory-based estimate. Extended across Alberta, our results suggest that reported venting emissions in Alberta should be 2.5 ± 0.5 times higher, and total methane emissions from the upstream oil and gas sector (excluding mined oil sands) are likely at least 25-50% greater than current government estimates. Successful mitigation efforts in the Red Deer region will need to focus on the >90% of methane emissions currently unmeasured or unreported.
Collapse
Affiliation(s)
- Matthew R Johnson
- Energy & Emissions Research Laboratory, Department of Mechanical and Aerospace Engineering, Carleton University , Ottawa, ON Canada , K1S 5B6
| | - David R Tyner
- Energy & Emissions Research Laboratory, Department of Mechanical and Aerospace Engineering, Carleton University , Ottawa, ON Canada , K1S 5B6
| | - Stephen Conley
- Scientific Aviation, Inc. , 3335 Airport Road Suite B, Boulder, Colorado 80301, United States
| | - Stefan Schwietzke
- CIRES/University of Colorado , NOAA ESRL Global Monitoring Division, 325 Broadway R/GMD 1, Boulder, Colorado 80305-3337, United States
| | - Daniel Zavala-Araiza
- Environmental Defense Fund , 301 Congress Avenue Suite 1300, Austin, Texas 78701, United States
| |
Collapse
|
27
|
Allen DT, Cardoso-Saldaña FJ, Kimura Y. Variability in Spatially and Temporally Resolved Emissions and Hydrocarbon Source Fingerprints for Oil and Gas Sources in Shale Gas Production Regions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12016-12026. [PMID: 28805050 DOI: 10.1021/acs.est.7b02202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A gridded inventory for emissions of methane, ethane, propane, and butanes from oil and gas sources in the Barnett Shale production region has been developed. This inventory extends previous spatially resolved inventories of emissions by characterizing the overall variability in emission magnitudes and the composition of emissions at an hourly time resolution. The inventory is divided into continuous and intermittent emission sources. Sources are defined as continuous if hourly averaged emissions are greater than zero in every hour; otherwise, they are classified as intermittent. In the Barnett Shale, intermittent sources accounted for 14-30% of the mean emissions for methane and 10-34% for ethane, leading to spatial and temporal variability in the location of hourly emissions. The combined variability due to intermittent sources and variability in emission factors can lead to wide confidence intervals in the magnitude and composition of time and location-specific emission inventories; therefore, including temporal and spatial variability in emission inventories is important when reconciling inventories and observations. Comparisons of individual aircraft measurement flights conducted in the Barnett Shale region versus the estimated emission rates for each flight from the emission inventory indicate agreement within the expected variability of the emission inventory for all flights for methane and for all but one flight for ethane.
Collapse
Affiliation(s)
- David T Allen
- Center for Energy and Environmental Resources, University of Texas at Austin , 10100 Burnet Road, Austin, Texas 78758, United States
| | - Felipe J Cardoso-Saldaña
- Center for Energy and Environmental Resources, University of Texas at Austin , 10100 Burnet Road, Austin, Texas 78758, United States
| | - Yosuke Kimura
- Center for Energy and Environmental Resources, University of Texas at Austin , 10100 Burnet Road, Austin, Texas 78758, United States
| |
Collapse
|
28
|
Robertson AM, Edie R, Snare D, Soltis J, Field RA, Burkhart MD, Bell CS, Zimmerle D, Murphy SM. Variation in Methane Emission Rates from Well Pads in Four Oil and Gas Basins with Contrasting Production Volumes and Compositions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017. [PMID: 28628305 DOI: 10.1021/acs.est.7b00571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Atmospheric methane emissions from active natural gas production sites in normal operation were quantified using an inverse Gaussian method (EPA's OTM 33a) in four major U.S. basins/plays: Upper Green River (UGR, Wyoming), Denver-Julesburg (DJ, Colorado), Uintah (Utah), and Fayetteville (FV, Arkansas). In DJ, Uintah, and FV, 72-83% of total measured emissions were from 20% of the well pads, while in UGR the highest 20% of emitting well pads only contributed 54% of total emissions. The total mass of methane emitted as a percent of gross methane produced, termed throughput-normalized methane average (TNMA) and determined by bootstrapping measurements from each basin, varied widely between basins and was (95% CI): 0.09% (0.05-0.15%) in FV, 0.18% (0.12-0.29%) in UGR, 2.1% (1.1-3.9%) in DJ, and 2.8% (1.0-8.6%) in Uintah. Overall, wet-gas basins (UGR, DJ, Uintah) had higher TNMA emissions than the dry-gas FV at all ranges of production per well pad. Among wet basins, TNMA emissions had a strong negative correlation with average gas production per well pad, suggesting that consolidation of operations onto single pads may reduce normalized emissions (average number of wells per pad is 5.3 in UGR versus 1.3 in Uintah and 2.8 in DJ).
Collapse
Affiliation(s)
- Anna M Robertson
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| | - Rachel Edie
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| | - Dustin Snare
- All4, Inc. , Kimberton, Pennsylvania 19442, United States
| | - Jeffrey Soltis
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| | - Robert A Field
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| | - Matthew D Burkhart
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| | - Clay S Bell
- Energy Institute and Mechanical Engineering, Colorado State University , 430 North College, Fort Collins, Colorado 80524, United States
| | - Daniel Zimmerle
- Energy Institute and Mechanical Engineering, Colorado State University , 430 North College, Fort Collins, Colorado 80524, United States
| | - Shane M Murphy
- Department of Atmospheric Science, University of Wyoming , 1000 East University Avenue, Laramie, Wyoming 82071, United States
| |
Collapse
|
29
|
Schwietzke S, Pétron G, Conley S, Pickering C, Mielke-Maday I, Dlugokencky EJ, Tans PP, Vaughn T, Bell C, Zimmerle D, Wolter S, King CW, White AB, Coleman T, Bianco L, Schnell RC. Improved Mechanistic Understanding of Natural Gas Methane Emissions from Spatially Resolved Aircraft Measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7286-7294. [PMID: 28548824 DOI: 10.1021/acs.est.7b01810] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Divergence in recent oil and gas related methane emission estimates between aircraft studies (basin total for a midday window) and emissions inventories (annualized regional and national statistics) indicate the need for better understanding the experimental design, including temporal and spatial alignment and interpretation of results. Our aircraft-based methane emission estimates in a major U.S. shale gas basin resolved from west to east show (i) similar spatial distributions for 2 days, (ii) strong spatial correlations with reported NG production (R2 = 0.75) and active gas well pad count (R2 = 0.81), and (iii) 2× higher emissions in the western half (normalized by gas production) despite relatively homogeneous dry gas and well characteristics. Operator reported hourly activity data show that midday episodic emissions from manual liquid unloadings (a routine operation in this basin and elsewhere) could explain ∼1/3 of the total emissions detected midday by the aircraft and ∼2/3 of the west-east difference in emissions. The 22% emission difference between both days further emphasizes that episodic sources can substantially impact midday methane emissions and that aircraft may detect daily peak emissions rather than daily averages that are generally employed in emissions inventories. While the aircraft approach is valid, quantitative, and independent, our study sheds new light on the interpretation of previous basin scale aircraft studies, and provides an improved mechanistic understanding of oil and gas related methane emissions.
Collapse
Affiliation(s)
- Stefan Schwietzke
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Gabrielle Pétron
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Stephen Conley
- Scientific Aviation, Inc. , 3335 Airport Road Suite B, Boulder, Colorado 80301, United States
- Department of Land, Air, and Water Resources, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Cody Pickering
- Department of Mechanical Engineering, Colorado State University , 400 Isotope Dr, Fort Collins, Colorado 80521, United States
| | - Ingrid Mielke-Maday
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Edward J Dlugokencky
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Pieter P Tans
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Tim Vaughn
- Department of Mechanical Engineering, Colorado State University , 400 Isotope Dr, Fort Collins, Colorado 80521, United States
| | - Clay Bell
- Department of Mechanical Engineering, Colorado State University , 400 Isotope Dr, Fort Collins, Colorado 80521, United States
| | - Daniel Zimmerle
- Department of Mechanical Engineering, Colorado State University , 400 Isotope Dr, Fort Collins, Colorado 80521, United States
| | - Sonja Wolter
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Clark W King
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Allen B White
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Timothy Coleman
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Laura Bianco
- Cooperative Institute for Research in Environmental Sciences, University of Colorado , 216 UCB, Boulder, Colorado 80309, United States
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| | - Russell C Schnell
- NOAA Earth System Research Laboratory , 325 Broadway, Boulder, Colorado 80305, United States
| |
Collapse
|
30
|
Zavala-Araiza D, Alvarez RA, Lyon DR, Allen DT, Marchese AJ, Zimmerle DJ, Hamburg SP. Super-emitters in natural gas infrastructure are caused by abnormal process conditions. Nat Commun 2017; 8:14012. [PMID: 28091528 PMCID: PMC5241676 DOI: 10.1038/ncomms14012] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/21/2016] [Indexed: 11/23/2022] Open
Abstract
Effectively mitigating methane emissions from the natural gas supply chain requires addressing the disproportionate influence of high-emitting sources. Here we use a Monte Carlo simulation to aggregate methane emissions from all components on natural gas production sites in the Barnett Shale production region (Texas). Our total emission estimates are two-thirds of those derived from independent site-based measurements. Although some high-emitting operations occur by design (condensate flashing and liquid unloadings), they occur more than an order of magnitude less frequently than required to explain the reported frequency at which high site-based emissions are observed. We conclude that the occurrence of abnormal process conditions (for example, malfunctions upstream of the point of emissions; equipment issues) cause additional emissions that explain the gap between component-based and site-based emissions. Such abnormal conditions can cause a substantial proportion of a site's gas production to be emitted to the atmosphere and are the defining attribute of super-emitting sites.
Collapse
Affiliation(s)
- Daniel Zavala-Araiza
- Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, USA
| | - Ramón A Alvarez
- Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, USA
| | - David R. Lyon
- Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, USA
| | - David T. Allen
- Center for Energy and Environmental Resources, The University of Texas at Austin, 10100 Burnet Road, Austin, Texas 78758, USA
| | - Anthony J. Marchese
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Daniel J. Zimmerle
- The Energy Institute, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Steven P. Hamburg
- Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, USA
| |
Collapse
|
31
|
Laurenzi IJ, Bergerson JA, Motazedi K. Life cycle greenhouse gas emissions and freshwater consumption associated with Bakken tight oil. Proc Natl Acad Sci U S A 2016; 113:E7672-E7680. [PMID: 27849573 PMCID: PMC5137726 DOI: 10.1073/pnas.1607475113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In recent years, hydraulic fracturing and horizontal drilling have been applied to extract crude oil from tight reservoirs, including the Bakken formation. There is growing interest in understanding the greenhouse gas (GHG) emissions associated with the development of tight oil. We conducted a life cycle assessment of Bakken crude using data from operations throughout the supply chain, including drilling and completion, refining, and use of refined products. If associated gas is gathered throughout the Bakken well life cycle, then the well to wheel GHG emissions are estimated to be 89 g CO2eq/MJ (80% CI, 87-94) of Bakken-derived gasoline and 90 g CO2eq/MJ (80% CI, 88-94) of diesel. If associated gas is flared for the first 12 mo of production, then life cycle GHG emissions increase by 5% on average. Regardless of the level of flaring, the Bakken life cycle GHG emissions are comparable to those of other crudes refined in the United States because flaring GHG emissions are largely offset at the refinery due to the physical properties of this tight oil. We also assessed the life cycle freshwater consumptions of Bakken-derived gasoline and diesel to be 1.14 (80% CI, 0.67-2.15) and 1.22 barrel/barrel (80% CI, 0.71-2.29), respectively, 13% of which is associated with hydraulic fracturing.
Collapse
Affiliation(s)
- Ian J Laurenzi
- Corporate Strategic Research, ExxonMobil Research and Engineering, Annandale, NJ 08801;
| | - Joule A Bergerson
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB Canada T2N 1N4
| | - Kavan Motazedi
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB Canada T2N 1N4
| |
Collapse
|
32
|
Brandt AR, Heath GA, Cooley D. Methane Leaks from Natural Gas Systems Follow Extreme Distributions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12512-12520. [PMID: 27740745 DOI: 10.1021/acs.est.6b04303] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ∼15 000 measurements from 18 prior studies, we show that all available natural gas leakage data sets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used log-normal model distributions, we show that log-normal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of data sets to increase sample size is not recommended due to apparent deviation between sampled populations. Understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.
Collapse
Affiliation(s)
- Adam R Brandt
- Department of Energy Resources Engineering, Stanford University , Stanford California 94305, United States
| | - Garvin A Heath
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Daniel Cooley
- Colorado State University , Fort Collins, Colorado 80523, United States
| |
Collapse
|
33
|
Airborne methane remote measurements reveal heavy-tail flux distribution in Four Corners region. Proc Natl Acad Sci U S A 2016; 113:9734-9. [PMID: 27528660 DOI: 10.1073/pnas.1605617113] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Methane (CH4) impacts climate as the second strongest anthropogenic greenhouse gas and air quality by influencing tropospheric ozone levels. Space-based observations have identified the Four Corners region in the Southwest United States as an area of large CH4 enhancements. We conducted an airborne campaign in Four Corners during April 2015 with the next-generation Airborne Visible/Infrared Imaging Spectrometer (near-infrared) and Hyperspectral Thermal Emission Spectrometer (thermal infrared) imaging spectrometers to better understand the source of methane by measuring methane plumes at 1- to 3-m spatial resolution. Our analysis detected more than 250 individual methane plumes from fossil fuel harvesting, processing, and distributing infrastructures, spanning an emission range from the detection limit [Formula: see text] 2 kg/h to 5 kg/h through [Formula: see text] 5,000 kg/h. Observed sources include gas processing facilities, storage tanks, pipeline leaks, and well pads, as well as a coal mine venting shaft. Overall, plume enhancements and inferred fluxes follow a lognormal distribution, with the top 10% emitters contributing 49 to 66% to the inferred total point source flux of 0.23 Tg/y to 0.39 Tg/y. With the observed confirmation of a lognormal emission distribution, this airborne observing strategy and its ability to locate previously unknown point sources in real time provides an efficient and effective method to identify and mitigate major emissions contributors over a wide geographic area. With improved instrumentation, this capability scales to spaceborne applications [Thompson DR, et al. (2016) Geophys Res Lett 43(12):6571-6578]. Further illustration of this potential is demonstrated with two detected, confirmed, and repaired pipeline leaks during the campaign.
Collapse
|
34
|
Abstract
Methane is a greenhouse gas, and increases in atmospheric methane concentration over the past 250 years have driven increased radiative forcing of the atmosphere. Increases in atmospheric methane concentration since 1750 account for approximately 17% of increases in radiative forcing of the atmosphere, and that percentage increases by approximately a factor of 2 if the effects of the greenhouse gases produced by the atmospheric reactions of methane are included in the assessment. Because of the role of methane emissions in radiative forcing of the atmosphere, the identification and quantification of sources of methane emissions is receiving increased scientific attention. Methane emission sources include biogenic, geogenic, and anthropogenic sources; the largest anthropogenic sources are natural gas and petroleum systems, enteric fermentation (livestock), landfills, coal mining, and manure management. While these source categories are well-known, there is significant uncertainty in the relative magnitudes of methane emissions from the various source categories. Further, the overall magnitude of methane emissions from all anthropogenic sources is actively debated, with estimates based on source sampling extrapolated to regional or national scale ("bottom-up analyses") differing from estimates that infer emissions based on ambient data ("top-down analyses") by 50% or more. To address the important problem of attribution of methane to specific sources, a variety of new analytical methods are being employed, including high time resolution and highly sensitive measurements of methane, methane isotopes, and other chemical species frequently associated with methane emissions, such as ethane. This Account describes the use of some of these emerging measurements, in both top-down and bottom-up methane emission studies. In addition, this Account describes how data from these new analytical methods can be used in conjunction with chemical mass balance (CMB) methods for source attribution. CMB methods have been developed over the past several decades to quantify sources of volatile organic compound (VOC) emissions and atmospheric particulate matter. These emerging capabilities for making measurements of methane and species coemitted with methane, rapidly, precisely, and at relatively low cost, used together with CMB methods of source attribution can lead to a better understanding of methane emission sources. Application of the CMB approach to source attribution in the Barnett Shale oil and gas production region in Texas demonstrates both the importance of extensive and simultaneous source testing in the region being analyzed and the potential of CMB method to quantify the relative strengths of methane emission sources.
Collapse
Affiliation(s)
- David Allen
- Department of Chemical Engineering
and Center for Energy and Environmental Resources University of Texas at Austin, Austin, Texas 78712, United States
| |
Collapse
|
35
|
Allen DT. Emissions from oil and gas operations in the United States and their air quality implications. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2016; 66:549-575. [PMID: 27249104 DOI: 10.1080/10962247.2016.1171263] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
UNLABELLED The energy supply infrastructure in the United States has been changing dramatically over the past decade. Increased production of oil and natural gas, particularly from shale resources using horizontal drilling and hydraulic fracturing, made the United States the world's largest producer of oil and natural gas in 2014. This review examines air quality impacts, specifically, changes in greenhouse gas, criteria air pollutant, and air toxics emissions from oil and gas production activities that are a result of these changes in energy supplies and use. National emission inventories indicate that volatile organic compound (VOC) and nitrogen oxide (NOx) emissions from oil and gas supply chains in the United States have been increasing significantly, whereas emission inventories for greenhouse gases have seen slight declines over the past decade. These emission inventories are based on counts of equipment and operational activities (activity factors), multiplied by average emission factors, and therefore are subject to uncertainties in these factors. Although uncertainties associated with activity data and missing emission source types can be significant, multiple recent measurement studies indicate that the greatest uncertainties are associated with emission factors. In many source categories, small groups of devices or sites, referred to as super-emitters, contribute a large fraction of emissions. When super-emitters are accounted for, multiple measurement approaches, at multiple scales, produce similar results for estimated emissions. Challenges moving forward include identifying super-emitters and reducing their emission magnitudes. Work done to date suggests that both equipment malfunction and operational practices can be important. Finally, although most of this review focuses on emissions from energy supply infrastructures, the regional air quality implications of some coupled energy production and use scenarios are examined. These case studies suggest that both energy production and use should be considered in assessing air quality implications of changes in energy infrastructures, and that impacts are likely to vary among regions. IMPLICATIONS The energy supply infrastructure in the United States has been changing dramatically over the past decade, leading to changes in emissions from oil and natural gas supply chain sources. In many source categories along these supply chains, small groups of devices or sites, referred to as super-emitters, contribute a large fraction of emissions. Effective emission reductions will require technologies for both identifying super-emitters and reducing their emission magnitudes.
Collapse
Affiliation(s)
- David T Allen
- a Department of Chemical Engineering, and Center for Energy and Environmental Resources , University of Texas , Austin , TX , USA
| |
Collapse
|
36
|
Lyon DR, Alvarez RA, Zavala-Araiza D, Brandt AR, Jackson RB, Hamburg SP. Aerial Surveys of Elevated Hydrocarbon Emissions from Oil and Gas Production Sites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:4877-4886. [PMID: 27045743 DOI: 10.1021/acs.est.6b00705] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Oil and gas (O&G) well pads with high hydrocarbon emission rates may disproportionally contribute to total methane and volatile organic compound (VOC) emissions from the production sector. In turn, these emissions may be missing from most bottom-up emission inventories. We performed helicopter-based infrared camera surveys of more than 8000 O&G well pads in seven U.S. basins to assess the prevalence and distribution of high-emitting hydrocarbon sources (detection threshold ∼ 1-3 g s(-1)). The proportion of sites with such high-emitting sources was 4% nationally but ranged from 1% in the Powder River (Wyoming) to 14% in the Bakken (North Dakota). Emissions were observed three times more frequently at sites in the oil-producing Bakken and oil-producing regions of mixed basins (p < 0.0001, χ(2) test). However, statistical models using basin and well pad characteristics explained 14% or less of the variance in observed emission patterns, indicating that stochastic processes dominate the occurrence of high emissions at individual sites. Over 90% of almost 500 detected sources were from tank vents and hatches. Although tank emissions may be partially attributable to flash gas, observed frequencies in most basins exceed those expected if emissions were effectively captured and controlled, demonstrating that tank emission control systems commonly underperform. Tanks represent a key mitigation opportunity for reducing methane and VOC emissions.
Collapse
Affiliation(s)
- David R Lyon
- Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
- Environmental Dynamics Program, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Ramón A Alvarez
- Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Daniel Zavala-Araiza
- Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Adam R Brandt
- Department of Energy Resources Engineering, Stanford University , Stanford, California 94305, United States
| | - Robert B Jackson
- Department of Earth System Science, Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University , Stanford, California 94305, United States
| | - Steven P Hamburg
- Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| |
Collapse
|
37
|
Peer RAM, Garrison JB, Timms CP, Sanders KT. Spatially and Temporally Resolved Analysis of Environmental Trade-Offs in Electricity Generation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:4537-4545. [PMID: 26967826 DOI: 10.1021/acs.est.5b05419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The US power sector is a leading contributor of emissions that affect air quality and climate. It also requires a lot of water for cooling thermoelectric power plants. Although these impacts affect ecosystems and human health unevenly in space and time, there has been very little quantification of these environmental trade-offs on decision-relevant scales. This work quantifies hourly water consumption, emissions (i.e., carbon dioxide, nitrogen oxides, and sulfur oxides), and marginal heat rates for 252 electricity generating units (EGUs) in the Electric Reliability Council of Texas (ERCOT) region in 2011 using a unit commitment and dispatch model (UC&D). Annual, seasonal, and daily variations, as well as spatial variability are assessed. When normalized over the grid, hourly average emissions and water consumption intensities (i.e., output per MWh) are found to be highest when electricity demand is the lowest, as baseload EGUs tend to be the most water and emissions intensive. Results suggest that a large fraction of emissions and water consumption are caused by a small number of power plants, mainly baseload coal-fired generators. Replacing 8-10 existing power plants with modern natural gas combined cycle units would result in reductions of 19-29%, 51-55%, 60-62%, and 13-27% in CO2 emissions, NOx emissions, SOx emissions, and water consumption, respectively, across the ERCOT region for two different conversion scenarios.
Collapse
Affiliation(s)
- Rebecca A M Peer
- Sonny Astani Department of Civil and Environmental Engineering, University of Southern California , 3620 S. Vermont Avenue, Los Angeles, California 90089-2531, United States
| | - Jared B Garrison
- Research Center for Energy Networks, ETH Zürich , Sonneggstrasse 28, SOI C 1, 8092 Zürich, Switzerland
| | - Craig P Timms
- Department of Electrical and Computer Engineering, University of Dayton , Kettering Laboratories 341, 300 College Park, Dayton, Ohio 45469-0232, United States
| | - Kelly T Sanders
- Sonny Astani Department of Civil and Environmental Engineering, University of Southern California , 3620 S. Vermont Avenue, Los Angeles, California 90089-2531, United States
| |
Collapse
|
38
|
Zavala-Araiza D, Lyon DR, Alvarez RA, Davis KJ, Harriss R, Herndon SC, Karion A, Kort EA, Lamb BK, Lan X, Marchese AJ, Pacala SW, Robinson AL, Shepson PB, Sweeney C, Talbot R, Townsend-Small A, Yacovitch TI, Zimmerle DJ, Hamburg SP. Reconciling divergent estimates of oil and gas methane emissions. Proc Natl Acad Sci U S A 2015; 112:15597-602. [PMID: 26644584 PMCID: PMC4697433 DOI: 10.1073/pnas.1522126112] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency's Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Anna Karion
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305
| | - Eric Adam Kort
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109
| | - Brian K Lamb
- Department of Civil and Environmental Engineering, Washington State University, Pullman, WA 99163
| | - Xin Lan
- Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77004
| | - Anthony J Marchese
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523
| | - Stephen W Pacala
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544;
| | - Allen L Robinson
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Paul B Shepson
- Department of Chemistry, Purdue University, West Lafayette, IN 47907
| | - Colm Sweeney
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305
| | - Robert Talbot
- Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77004
| | | | | | - Daniel J Zimmerle
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523
| | | |
Collapse
|
39
|
Yao Y, Graziano DJ, Riddle M, Cresko J, Masanet E. Understanding Variability To Reduce the Energy and GHG Footprints of U.S. Ethylene Production. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:14704-14716. [PMID: 26523461 DOI: 10.1021/acs.est.5b03851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recent growth in U.S. ethylene production due to the shale gas boom is affecting the U.S. chemical industry's energy and greenhouse gas (GHG) emissions footprints. To evaluate these effects, a systematic, first-principles model of the cradle-to-gate ethylene production system was developed and applied. The variances associated with estimating the energy consumption and GHG emission intensities of U.S. ethylene production, both from conventional natural gas and from shale gas, are explicitly analyzed. A sensitivity analysis illustrates that the large variances in energy intensity are due to process parameters (e.g., compressor efficiency), and that large variances in GHG emissions intensity are due to fugitive emissions from upstream natural gas production. On the basis of these results, the opportunities with the greatest leverage for reducing the energy and GHG footprints are presented. The model and analysis provide energy analysts and policy makers with a better understanding of the drivers of energy use and GHG emissions associated with U.S. ethylene production. They also constitute a rich data resource that can be used to evaluate options for managing the industry's footprints moving forward.
Collapse
Affiliation(s)
- Yuan Yao
- Department of Chemical & Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60201, United States
| | - Diane J Graziano
- Global Security Sciences Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Matthew Riddle
- Energy Systems Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Joe Cresko
- Advanced Manufacturing Office, U.S. Department of Energy , 1000 Independence Avenue, SW, Washington, DC 20585, United States
| | - Eric Masanet
- Department of Chemical & Biological Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60201, United States
- Department of Mechanical Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60201, United States
| |
Collapse
|
40
|
Marchese AJ, Vaughn TL, Zimmerle DJ, Martinez DM, Williams LL, Robinson AL, Mitchell AL, Subramanian R, Tkacik DS, Roscioli JR, Herndon SC. Methane Emissions from United States Natural Gas Gathering and Processing. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10718-27. [PMID: 26281719 DOI: 10.1021/acs.est.5b02275] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
New facility-level methane (CH4) emissions measurements obtained from 114 natural gas gathering facilities and 16 processing plants in 13 U.S. states were combined with facility counts obtained from state and national databases in a Monte Carlo simulation to estimate CH4 emissions from U.S. natural gas gathering and processing operations. Total annual CH4 emissions of 2421 (+245/-237) Gg were estimated for all U.S. gathering and processing operations, which represents a CH4 loss rate of 0.47% (±0.05%) when normalized by 2012 CH4 production. Over 90% of those emissions were attributed to normal operation of gathering facilities (1697 +189/-185 Gg) and processing plants (506 +55/-52 Gg), with the balance attributed to gathering pipelines and processing plant routine maintenance and upsets. The median CH4 emissions estimate for processing plants is a factor of 1.7 lower than the 2012 EPA Greenhouse Gas Inventory (GHGI) estimate, with the difference due largely to fewer reciprocating compressors, and a factor of 3.0 higher than that reported under the EPA Greenhouse Gas Reporting Program. Since gathering operations are currently embedded within the production segment of the EPA GHGI, direct comparison to our results is complicated. However, the study results suggest that CH4 emissions from gathering are substantially higher than the current EPA GHGI estimate and are equivalent to 30% of the total net CH4 emissions in the natural gas systems GHGI. Because CH4 emissions from most gathering facilities are not reported under the current rule and not all source categories are reported for processing plants, the total CH4 emissions from gathering and processing reported under the EPA GHGRP (180 Gg) represents only 14% of that tabulated in the EPA GHGI and 7% of that predicted from this study.
Collapse
Affiliation(s)
- Anthony J Marchese
- Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80523, United States
| | - Timothy L Vaughn
- Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80523, United States
| | - Daniel J Zimmerle
- The Energy Institute, Colorado State University , Fort Collins, Colorado 80523, United States
| | - David M Martinez
- Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80523, United States
| | | | - Allen L Robinson
- Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Austin L Mitchell
- Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - R Subramanian
- Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Daniel S Tkacik
- Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Joseph R Roscioli
- Aerodyne Research Inc. , Billerica, Massachusetts 01821, United States
| | - Scott C Herndon
- Aerodyne Research Inc. , Billerica, Massachusetts 01821, United States
| |
Collapse
|
41
|
Zimmerle DJ, Williams LL, Vaughn TL, Quinn C, Subramanian R, Duggan GP, Willson B, Opsomer JD, Marchese AJ, Martinez DM, Robinson AL. Methane Emissions from the Natural Gas Transmission and Storage System in the United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015. [PMID: 26195284 DOI: 10.1021/acs.est.5b01669] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The recent growth in production and utilization of natural gas offers potential climate benefits, but those benefits depend on lifecycle emissions of methane, the primary component of natural gas and a potent greenhouse gas. This study estimates methane emissions from the transmission and storage (T&S) sector of the United States natural gas industry using new data collected during 2012, including 2,292 onsite measurements, additional emissions data from 677 facilities and activity data from 922 facilities. The largest emission sources were fugitive emissions from certain compressor-related equipment and "super-emitter" facilities. We estimate total methane emissions from the T&S sector at 1,503 [1,220 to 1,950] Gg/yr (95% confidence interval) compared to the 2012 Environmental Protection Agency's Greenhouse Gas Inventory (GHGI) estimate of 2,071 [1,680 to 2,690] Gg/yr. While the overlap in confidence intervals indicates that the difference is not statistically significant, this is the result of several significant, but offsetting, factors. Factors which reduce the study estimate include a lower estimated facility count, a shift away from engines toward lower-emitting turbine and electric compressor drivers, and reductions in the usage of gas-driven pneumatic devices. Factors that increase the study estimate relative to the GHGI include updated emission rates in certain emission categories and explicit treatment of skewed emissions at both component and facility levels. For T&S stations that are required to report to the EPA's Greenhouse Gas Reporting Program (GHGRP), this study estimates total emissions to be 260% [215% to 330%] of the reportable emissions for these stations, primarily due to the inclusion of emission sources that are not reported under the GHGRP rules, updated emission factors, and super-emitter emissions.
Collapse
Affiliation(s)
- Daniel J Zimmerle
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Laurie L Williams
- ‡Department of Physics and Engineering, Fort Lewis College, Durango, Colorado 81301, United States
| | - Timothy L Vaughn
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Casey Quinn
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - R Subramanian
- §Center for Atmospheric Particle Studies (CAPS) and the Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Gerald P Duggan
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Bryan Willson
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Jean D Opsomer
- ∥Department of Statistics, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Anthony J Marchese
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - David M Martinez
- †Energy Institute and Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524, United States
| | - Allen L Robinson
- §Center for Atmospheric Particle Studies (CAPS) and the Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| |
Collapse
|
42
|
Zavala-Araiza D, Lyon D, Alvarez RA, Palacios V, Harriss R, Lan X, Talbot R, Hamburg SP. Toward a Functional Definition of Methane Super-Emitters: Application to Natural Gas Production Sites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8167-74. [PMID: 26148555 DOI: 10.1021/acs.est.5b00133] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Emissions from natural gas production sites are characterized by skewed distributions, where a small percentage of sites-commonly labeled super-emitters-account for a majority of emissions. A better characterization of super-emitters is needed to operationalize ways to identify them and reduce emissions. We designed a conceptual framework that functionally defines superemitting sites as those with the highest proportional loss rates (methane emitted relative to methane produced). Using this concept, we estimated total methane emissions from natural gas production sites in the Barnett Shale; functionally superemitting sites accounted for roughly three-fourths of total emissions. We discuss the potential to reduce emissions from these sites, under the assumption that sites with high proportional loss rates have excess emissions resulting from abnormal or otherwise avoidable operating conditions, such as malfunctioning equipment. Because the population of functionally superemitting sites is not expected to be static over time, continuous monitoring will likely be necessary to identify them and improve their operation. This work suggests that achieving and maintaining uniformly low emissions across the entire population of production sites will require mitigation steps at a large fraction of sites.
Collapse
Affiliation(s)
- Daniel Zavala-Araiza
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - David Lyon
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Ramón A Alvarez
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Virginia Palacios
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Robert Harriss
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Xin Lan
- ‡Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, United States
| | - Robert Talbot
- ‡Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, United States
| | - Steven P Hamburg
- §Environmental Defense Fund, 18 Tremont Street, Boston, Massachusetts 02108, United States
| |
Collapse
|
43
|
Lyon DR, Zavala-Araiza D, Alvarez RA, Harriss R, Palacios V, Lan X, Talbot R, Lavoie T, Shepson P, Yacovitch TI, Herndon SC, Marchese AJ, Zimmerle D, Robinson AL, Hamburg SP. Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8147-57. [PMID: 26148553 DOI: 10.1021/es506359c] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Methane emissions from the oil and gas industry (O&G) and other sources in the Barnett Shale region were estimated by constructing a spatially resolved emission inventory. Eighteen source categories were estimated using multiple data sets, including new empirical measurements at regional O&G sites and a national study of gathering and processing facilities. Spatially referenced activity data were compiled from federal and state databases and combined with O&G facility emission factors calculated using Monte Carlo simulations that account for high emission sites representing the very upper portion, or fat-tail, in the observed emissions distributions. Total methane emissions in the 25-county Barnett Shale region in October 2013 were estimated to be 72,300 (63,400-82,400) kg CH4 h(-1). O&G emissions were estimated to be 46,200 (40,000-54,100) kg CH4 h(-1) with 19% of emissions from fat-tail sites representing less than 2% of sites. Our estimate of O&G emissions in the Barnett Shale region was higher than alternative inventories based on the United States Environmental Protection Agency (EPA) Greenhouse Gas Inventory, EPA Greenhouse Gas Reporting Program, and Emissions Database for Global Atmospheric Research by factors of 1.5, 2.7, and 4.3, respectively. Gathering compressor stations, which accounted for 40% of O&G emissions in our inventory, had the largest difference from emission estimates based on EPA data sources. Our inventory's higher O&G emission estimate was due primarily to its more comprehensive activity factors and inclusion of emissions from fat-tail sites.
Collapse
Affiliation(s)
- David R Lyon
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
- ‡Environmental Dynamics Program, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Daniel Zavala-Araiza
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Ramón A Alvarez
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Robert Harriss
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Virginia Palacios
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| | - Xin Lan
- §Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, United States
| | - Robert Talbot
- §Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, United States
| | - Tegan Lavoie
- ∥Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Paul Shepson
- ∥Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tara I Yacovitch
- ⊥Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States
| | - Scott C Herndon
- ⊥Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States
| | - Anthony J Marchese
- #Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Daniel Zimmerle
- #Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Allen L Robinson
- ∇Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Steven P Hamburg
- †Environmental Defense Fund, 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States
| |
Collapse
|
44
|
Tong F, Jaramillo P, Azevedo IML. Comparison of life cycle greenhouse gases from natural gas pathways for medium and heavy-duty vehicles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:7123-7133. [PMID: 25938939 DOI: 10.1021/es5052759] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The low-cost and abundant supply of shale gas in the United States has increased the interest in using natural gas for transportation. We compare the life cycle greenhouse gas (GHG) emissions from different natural gas pathways for medium and heavy-duty vehicles (MHDVs). For Class 8 tractor-trailers and refuse trucks, none of the natural gas pathways provide emissions reductions per unit of freight-distance moved compared to diesel trucks. When compared to the petroleum-based fuels currently used in these vehicles, CNG and centrally produced LNG increase emissions by 0-3% and 2-13%, respectively, for Class 8 trucks. Battery electric vehicles (BEVs) powered with natural gas-produced electricity are the only fuel-technology combination that achieves emission reductions for Class 8 transit buses (31% reduction compared to the petroleum-fueled vehicles). For non-Class 8 trucks (pick-up trucks, parcel delivery trucks, and box trucks), BEVs reduce emissions significantly (31-40%) compared to their diesel or gasoline counterparts. CNG and propane achieve relatively smaller emissions reductions (0-6% and 19%, respectively, compared to the petroleum-based fuels), while other natural gas pathways increase emissions for non-Class 8 MHDVs. While using natural gas to fuel electric vehicles could achieve large emission reductions for medium-duty trucks, the results suggest there are no great opportunities to achieve large emission reductions for Class 8 trucks through natural gas pathways with current technologies. There are strategies to reduce the carbon footprint of using natural gas for MHDVs, ranging from increasing vehicle fuel efficiency, reducing life cycle methane leakage rate, to achieving the same payloads and cargo volumes as conventional diesel trucks.
Collapse
Affiliation(s)
- Fan Tong
- Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Paulina Jaramillo
- Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Inês M L Azevedo
- Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| |
Collapse
|
45
|
Hays J, Finkel ML, Depledge M, Law A, Shonkoff SBC. Considerations for the development of shale gas in the United Kingdom. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 512-513:36-42. [PMID: 25613768 DOI: 10.1016/j.scitotenv.2015.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/29/2014] [Accepted: 01/03/2015] [Indexed: 06/04/2023]
Abstract
The United States shale gas boom has precipitated global interest in the development of unconventional oil and gas resources. Recently, government ministers in the United Kingdom started granting licenses that will enable companies to begin initial exploration for shale gas. Meanwhile, concern is increasing among the scientific community about the potential impacts of shale gas and other types of unconventional natural gas development (UGD) on human health and the environment. Although significant data gaps remain, there has been a surge in the number of articles appearing in the scientific literature, nearly three-quarters of which has been published since the beginning of 2013. Important lessons can be drawn from the UGD experience in the United States. Here we explore these considerations and argue that shale gas development policies in the UK and elsewhere should be informed by empirical evidence generated on environmental, public health, and social risks. Additionally, policy decisions should take into account the measured effectiveness of harm reduction strategies as opposed to hypothetical scenarios and purported best practices that lack empirical support.
Collapse
Affiliation(s)
- Jake Hays
- PSE Healthy Energy, United States; Weill Cornell Medical College, 402 East 67th St. New York, NY 10065, United States.
| | - Madelon L Finkel
- Weill Cornell Medical College, 402 East 67th St. New York, NY 10065, United States
| | | | - Adam Law
- Weill Cornell Medical College, 402 East 67th St. New York, NY 10065, United States
| | - Seth B C Shonkoff
- PSE Healthy Energy, United States; University of California, Berkeley, United States
| |
Collapse
|