Characteristics of urban street level methane emissions in Bucharest, Romania

Romania has a complex geological history resulting in a very hydrocarbon rich region that is heavily exploited and utilised. Romania&#8217;s Fourth Biennial Report under the UNFCCC states that methane (CH4) emissions have decreased by 61% between 1989 and 2017, which is a result of decreases in fugitive fossil fuel and livestock emissions. Although there is a decreasing trend of CH4 levels in most of Europe, we still see an overall increase in atmospheric CH4 concentrations. As atmospheric CH4 continues to increase and the mitigation of greenhouse gases becomes more of a concern, it is important to address CH4 emissions from large cities.&#160; Here we ask the question: What are the major sources of urban methane emissions in Romania&#8217;s city capital, Bucharest? Together, street level continuous measurements of CH4 and ethane (C2H6), and &#948;13C-CH4 & &#948;2H-CH4 of high concentration plumes assist in the identification of emissions, both for major point sources and small leaks from the natural gas distribution system.&#160;Urban focused surveys were conducted in Bucharest during August of 2019. Three continuously-measuring instruments were used, including an LGR Ultraportable CH4/C2H6 analyzer, allowing for the separation of natural gas leaks from other source category emissions. CH4 and C2H6 have been mapped to find locations of elevated mixing ratios above background. Air samples were collected from an inlet on the vehicle bumper (60 cm above ground) that is connected to a bag pump, filling 3L Flexfoil bags.&#160; Samples were then analyzed for &#948;13C-CH4 & &#948;2H-CH4 using an IsoPrime Trace Gas continuous flow gas chromatograph isotope ratio mass spectrometer (CF GC-IRMS) at Royal Holloway, University of London and a Thermo Fisher Delta Plus XP, at Utrecht University. Background baselines of CH4 and isotopic ratios were statistically determined while traveling and distinguished from the various plumes of high concentrations. Point source signatures were then calculated using Keeling plot analysis. C2:C1 ratios from specific emissions types were compared with the correlated &#948;13CCH4 values.&#160;Detailed urban methane mapping and the use of high precision isotopic source signature measurements provide an efficient approach to identifying and sourcing small gas leaks in urban cities. These results will be useful in future government regulation of greenhouse gas emissions in urban areas as the EU continues to work on the reduction of greenhouse gases.

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On Methane Leaks from Pipelines in Bryan and College Station, Texas, USA

The Open Atmospheric Science Journal ◽

10.2174/1874282301610010056 ◽

2016 ◽

Vol 10 (1) ◽

pp. 56-62 ◽

Cited By ~ 1

Author(s):

Kristen Koch ◽

Shelby Thomas ◽

Elora Arana ◽

Geoff Roest ◽

Gunnar W. Schade

Keyword(s):

Natural Gas ◽

Distribution System ◽

Urban Areas ◽

Fossil Fuel ◽

Fast Response ◽

Metropolitan Region ◽

Pipeline System ◽

Domestic Ruminants ◽

The Us ◽

Gas Leaks

Methane is the second most important anthropogenically emitted greenhouse gas after carbon dioxide. Anthropogenic methane sources in the US are dominated by emissions from domestic ruminants and from fossil fuel exploration, storage and transmission. The fossil fuel source is primarily due to natural gas leaks along the production to distribution chain, and pipeline leaks in urban areas have been identified as a significant contributor. In this study, we evaluated possible leaks in three neighborhoods of a midsize Texas metropolitan region surrounding Texas A&M University through mobile measurements using a fast response, high precision methane analyzer. Neighborhoods were selected by age and land use, and each predetermined driving route was evaluated three times. Methane spikes exceeding 2.5 ppm were identified as leaks, and approximately one leak per mile of urban road was discovered. The largest leaks were found around the Texas A&M natural gas plant and in the oldest neighborhood to its north, while fewer leaks were found in a slightly younger neighborhood. No leaks were found in the youngest, less than 20-year old neighborhood suggesting that pipeline system age is a strong determinant of current and future leaks from the natural gas distribution system.

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Vista-LA: Mapping methane emitting infrastructure in the Los Angeles megacity

10.5194/essd-2017-65 ◽

2017 ◽

Cited By ~ 2

Author(s):

Valerie Carranza ◽

Talha Rafiq ◽

Isis Frausto-Vicencio ◽

Francesca Hopkins ◽

Kristal R. Verhulst ◽

...

Keyword(s):

Los Angeles ◽

Urban Areas ◽

Hot Spot ◽

Complex Mixture ◽

Methane Emissions ◽

Point Sources ◽

Climate Mitigation ◽

Analysis Tool ◽

Oak Ridge ◽

Methane Source

Abstract. Methane is a potent greenhouse gas (GHG) and a critical target of climate mitigation efforts. However, actionable emission reduction efforts are complicated by large uncertainties in the methane budget at relevant scales. Here, we present Vista, a Geographic Information System (GIS)-based approach to map potential methane emissions sources in greater Los Angeles, an area with a dense, complex mixture of sources. The goal of this work is to provide a database that, together with atmospheric observations, improves methane emissions estimates in urban areas with complex infrastructure. We aggregated methane source location information into three sectors (energy, agriculture, and waste) following the frameworks used by the State of California GHG Inventory and the IPCC Guidelines for GHG Reporting. Geospatial modelling was applied to publicly available datasets to precisely geolocate facilities and infrastructure comprising major anthropogenic methane source sectors. The final database, Vista-Los Angeles (LA), is presented as maps of infrastructure known or expected to emit methane. Vista-LA contains over 33,000 features concentrated on <1% of land area in the region. Currently, Vista-LA is used as a planning and analysis tool for atmospheric measurement surveys of methane sources, particularly for airborne remote sensing, and methane “hot-spot” detection using regional observations. This study represents a first step towards developing an accurate, spatially-resolved methane flux estimate for point sources in California’s South Coast Air Basin (SoCAB), with the potential to address discrepancies between bottom-up and top-down methane emissions accounting. The final Vista-LA datasets and associated metadata have been submitted to the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics (ORNL DAAC; https://doi.org/10.3334/ORNLDAAC/1525).

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Background heterogeneity and other uncertainties in estimating urban methane flux: results from the Indianapolis Flux Experiment (INFLUX)

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-4545-2020 ◽

2020 ◽

Vol 20 (7) ◽

pp. 4545-4559 ◽

Cited By ~ 1

Author(s):

Nikolay V. Balashov ◽

Kenneth J. Davis ◽

Natasha L. Miles ◽

Thomas Lauvaux ◽

Scott J. Richardson ◽

...

Keyword(s):

Natural Gas ◽

Mole Fraction ◽

Inverse Modeling ◽

Distribution System ◽

Single Point ◽

Domain Size ◽

Atmospheric Modeling ◽

Point Sources ◽

Ch4 Emissions

Abstract. As natural gas extraction and use continues to increase, the need to quantify emissions of methane (CH4), a powerful greenhouse gas, has grown. Large discrepancies in Indianapolis CH4 emissions have been observed when comparing inventory, aircraft mass balance, and tower inverse modeling estimates. Four years of continuous CH4 mole fraction observations from a network of nine towers as a part of the Indianapolis Flux Experiment (INFLUX) are utilized to investigate four possible reasons for the abovementioned inconsistencies: (1) differences in definition of the city domain, (2) a highly temporally variable and spatially non-uniform CH4 background, (3) temporal variability in CH4 emissions, and (4) CH4 sources that are not accounted for in the inventory. Reducing the Indianapolis urban domain size to be consistent with the inventory domain size decreases the CH4 emission estimation of the inverse modeling methodology by about 35 %, thereby lessening the discrepancy and bringing total city flux within the error range of one of the two inventories. Nevertheless, the inverse modeling estimate still remains about 91 % higher than inventory estimates. Hourly urban background CH4 mole fractions are shown to be spatially heterogeneous and temporally variable. Variability in background mole fractions observed at any given moment and a single location could be up to about 50 ppb depending on a wind direction but decreases substantially when averaged over multiple days. Statistically significant, long-term biases in background mole fractions of 2–5 ppb are found from single-point observations for most wind directions. Boundary layer budget estimates suggest that Indianapolis CH4 emissions did not change significantly when comparing 2014 to 2016. However, it appears that CH4 emissions may follow a diurnal cycle, with daytime emissions (12:00–16:00 LST) approximately twice as large as nighttime emissions (20:00–05:00 LST). We found no evidence for large CH4 point sources that are otherwise missing from the inventories. The data from the towers confirm that the strongest CH4 source in Indianapolis is South Side landfill. Leaks from the natural gas distribution system that were detected with the tower network appeared localized and non-permanent. Our simple atmospheric budget analyses estimate the magnitude of the diffuse natural gas source to be 70 % higher than inventory estimates, but more comprehensive analyses are needed. Long-term averaging, spatially extensive upwind mole fraction observations, mesoscale atmospheric modeling of the regional emissions environment, and careful treatment of the times of day are recommended for precise and accurate quantification of urban CH4 emissions.

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Background Heterogeneity and Other Uncertainties in Estimating Urban Methane Flux: Results from the Indianapolis Flux (INFLUX) Experiment

10.5194/acp-2019-48 ◽

2019 ◽

Cited By ~ 1

Author(s):

Nikolay V. Balashov ◽

Kenneth J. Davis ◽

Natasha L. Miles ◽

Thomas Lauvaux ◽

Scott J. Richardson ◽

...

Keyword(s):

Natural Gas ◽

Mole Fraction ◽

Inverse Modeling ◽

Distribution System ◽

Single Point ◽

Domain Size ◽

Atmospheric Modeling ◽

Point Sources ◽

Ch4 Emissions

Abstract. As natural gas extraction and use continues to increase, the need to quantify emissions of methane (CH4), a powerful greenhouse gas, has grown. Large discrepancies in Indianapolis CH4 emissions have been observed when comparing inventory, aircraft mass-balance, and tower inverse modeling estimates. Four years of continuous CH4 mole fraction observations from a network of nine tower-based cavity ring-down spectrometers measuring atmospheric CH4 mole fractions at 39 to 136 m above ground as part of the Indianapolis Flux Experiment (INFLUX) are utilized to investigate four possible reasons for the abovementioned inconsistencies: (1) differences in definition of the city domain, (2) a highly temporally variable and spatially non-uniform CH4 background, (3) temporal variability in CH4 emissions, and (4) the presence of unknown CH4 sources. Reducing the Indianapolis urban domain size to be consistent with the inventory domain size decreases the CH4 emission estimation of the inverse modeling methodology by about 35 % and thereby lessens the discrepancy by bringing total city flux within an error range of one of the inventories. Nevertheless, the inverse modeling estimate still remains about 40 % higher than the inventory value. Hourly urban background CH4 mole fractions are shown to be heterogeneous and temporally variable. Statistically significant, long-term biases in background mole fractions of 2–5 ppb are found from single point observations from most wind directions. Random errors in single point background mole fractions observed for a few hours are 20–30 ppb, but decrease substantially when data are averaged over multiple days. Boundary layer budget estimates suggest that Indianapolis CH4 emissions did not change significantly when comparing 2014 to 2016. However, it appears that CH4 emissions may follow a diurnal cycle with daytime emissions (12–16 LST) approximately twice as large as nighttime emissions (20–5 LST). The strongest CH4 source in Indianapolis is the South Side Landfill. Other point sources, perhaps leaks from the natural gas distribution system, are localized and transient, and do not appear to be a consistently large source of CH4 emissions in Indianapolis. Long-term averaging, spatially-extensive upwind mole fraction observations, mesoscale atmospheric modeling of the regional emissions environment, and careful treatment of the times of day and areal representation of emission estimates is recommended for precise and accurate quantification of urban CH4 emissions.

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Systematic approach to natural gas usage for domestic heating in urban areas

10.31219/osf.io/g2ws5 ◽

2017 ◽

Author(s):

Dejan Brkić ◽

Toma I. Tanasković

Keyword(s):

Natural Gas ◽

Distribution System ◽

Urban Areas ◽

Energy Supply ◽

District Heating ◽

Heating System ◽

Gas Distribution ◽

Coordinated Development ◽

Supply Systems ◽

Selection Of

Natural gas can be used for satisfying population needs for heating, either directly by bringing the gas to the dwellings through the gas distribution system and combusting it in the domestic boiler (gas distribution system—G) or indirectly by combusting the natural gas in the heating plant and distributing the heat energy to the dwellings through the district-heating (DH) system. The selection of a certain type of heating system is made according to the disposition of buildings in the area, their number, size, insulation quality, etc. Based on these characteristics, calculations of investments and exploitation costs have been made for both heating systems and a comparison has been made for all of the 96 presented cases. Almost each type of real settlement can be represented by one of the types of the conditional urban area that are introduced in the paper. The main goal of this paper is to establish a general model to achieve coordinated development of centralized energy supply systems fueled by natural gas, based on defined and accepted criteria. A structure analysis of centralized systems for energy supply has been done with accent on their pipelines.

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Assessing Urban Methane Emissions using Column Observing Portable FTIR Spectrometers and a Novel Bayesian Inversion Framework

10.5194/acp-2020-1262 ◽

2021 ◽

Author(s):

Taylor S. Jones ◽

Jonathan E. Franklin ◽

Jia Chen ◽

Florian Dietrich ◽

Kristian D. Hajny ◽

...

Keyword(s):

Natural Gas ◽

Urban Areas ◽

Transport Model ◽

Methane Emissions ◽

Surface Fluxes ◽

Bayesian Inversion ◽

Inversion Method ◽

Bottom Up ◽

The City ◽

Total Column

Abstract. Cities represent a large and concentrated portion of global greenhouse gas emissions, including methane. Quantifying methane emissions from urban areas is difficult, and inventories made using bottom-up accounting methods often differ greatly from top-down estimates generated from atmospheric observations. Emissions from leaks in natural gas infrastructure are difficult to predict, and are therefore poorly constrained in bottom-up inventories. Natural gas infrastructure leaks and emissions from end uses can be spread throughout the city, and this diffuse source can represent a significant fraction of a city's total emissions. We investigated diffuse methane emissions of the city of Indianapolis, USA during a field campaign in May of 2016. A network of five portable solar-tracking Fourier transform infrared (FTIR) spectrometers was deployed throughout the city. These instruments measure the mole fraction of methane in a total column of air, giving them sensitivity to larger areas of the city than in situ sensors at the surface. We present an innovative inversion method to link these total column concentrations to surface fluxes. This method combines a Lagrangian transport model with a Bayesian inversion framework to estimate surface emissions and their uncertainties, together with determining the concentrations of methane in the air flowing into the city. Variations exceeding 10 ppb were observed in the inflowing air on a typical day, somewhat larger than the enhancements due to urban emissions (

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Vista-LA: Mapping methane-emitting infrastructure in the Los Angeles megacity

Earth System Science Data ◽

10.5194/essd-10-653-2018 ◽

2018 ◽

Vol 10 (1) ◽

pp. 653-676 ◽

Cited By ~ 6

Author(s):

Valerie Carranza ◽

Talha Rafiq ◽

Isis Frausto-Vicencio ◽

Francesca M. Hopkins ◽

Kristal R. Verhulst ◽

...

Keyword(s):

Los Angeles ◽

Urban Areas ◽

National Laboratory ◽

Complex Mixture ◽

Methane Emissions ◽

Point Sources ◽

Climate Mitigation ◽

Analysis Tool ◽

Oak Ridge ◽

Methane Source

Abstract. Methane (CH4) is a potent greenhouse gas (GHG) and a critical target of climate mitigation efforts. However, actionable emission reduction efforts are complicated by large uncertainties in the methane budget on relevant scales. Here, we present Vista, a Geographic Information System (GIS)-based approach to map potential methane emissions sources in the South Coast Air Basin (SoCAB) that encompasses Los Angeles, an area with a dense, complex mixture of methane sources. The goal of this work is to provide a database that, together with atmospheric observations, improves methane emissions estimates in urban areas with complex infrastructure. We aggregated methane source location information into three sectors (energy, agriculture, and waste) following the frameworks used by the State of California GHG Inventory and the Intergovernmental Panel on Climate Change (IPCC) Guidelines for GHG Reporting. Geospatial modeling was applied to publicly available datasets to precisely geolocate facilities and infrastructure comprising major anthropogenic methane source sectors. The final database, Vista-Los Angeles (Vista-LA), is presented as maps of infrastructure known or expected to emit CH4. Vista-LA contains over 33 000 features concentrated on <  1 % of land area in the region. Currently, Vista-LA is used as a planning and analysis tool for atmospheric measurement surveys of methane sources, particularly for airborne remote sensing, and methane hotspot detection using regional observations. This study represents a first step towards developing an accurate, spatially resolved methane flux estimate for point sources in SoCAB, with the potential to address discrepancies between bottom–up and top–down methane emissions accounting in this region. The Vista-LA datasets and associated metadata are available from the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics (ORNL DAAC; https://doi.org/10.3334/ORNLDAAC/1525).

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Air Emissions from Natural Gas Facilities in New York State

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16091591 ◽

2019 ◽

Vol 16 (9) ◽

pp. 1591 ◽

Cited By ~ 3

Author(s):

Pasquale N. Russo ◽

David O. Carpenter

Keyword(s):

New York ◽

Natural Gas ◽

Greenhouse Gases ◽

Distribution System ◽

Air Pollutants ◽

New York State ◽

The State ◽

Gas Pipelines ◽

Emissions Inventory ◽

Natural Gas Pipelines

While New York has banned fracking, new and expanded natural gas pipelines are being constructed across the state. Our previous studies have reported that compressor stations are a major source of air pollution at fracking sites. We have used two federal datasets, the U.S. Environmental Protection Agency’s (EPA) National Emissions Inventory and Greenhouse Gas Inventory, to determine what is known concerning emissions from the compressor stations along natural gas pipelines in the state. From a total of 74 compressor stations only 18 report to EPA on emissions. In the seven year period between 2008 and 2014 they released a total of 36.99 million pounds of air pollutants, not including CO2 and methane. This included emissions of 39 chemicals known to be human carcinogens. There was in addition 6.1 billion pounds of greenhouse gases release from ten stations in a single year. These data clearly underestimate the total releases from the state’s natural gas transportation and distribution system. However, they demonstrate significant releases of air pollutants, some of which are known to cause human disease. In addition, they release large amounts of greenhouse gases that contribute to climate change.

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