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

2019 ◽  
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.

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

2020 ◽  
Vol 20 (7) ◽  
pp. 4545-4559 ◽  
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.

Characteristics of urban street level methane emissions in Bucharest, Romania

2020 ◽  
Author(s):  
Julianne Fernandez ◽  
James France ◽  
Malika Menoud ◽  
Hossein Maazallahi ◽  
Marius-Paul Corbu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Greenhouse Gases ◽  
Distribution System ◽  
Urban Areas ◽  
Methane Emissions ◽  
Point Sources ◽  
Measuring Instruments ◽  
High Concentration ◽  
Street Level ◽  
Gas Leaks

<p>Romania has a complex geological history resulting in a very hydrocarbon rich region that is heavily exploited and utilised. Romania’s Fourth Biennial Report under the UNFCCC states that methane (CH<sub>4</sub>) 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 CH<sub>4</sub> levels in most of Europe, we still see an overall increase in atmospheric CH<sub>4</sub> concentrations. As atmospheric CH<sub>4</sub> continues to increase and the mitigation of greenhouse gases becomes more of a concern, it is important to address CH<sub>4</sub> emissions from large cities.  Here we ask the question: What are the major sources of urban methane emissions in Romania’s city capital, Bucharest? Together, street level continuous measurements of CH<sub>4</sub> and ethane (C<sub>2</sub>H<sub>6</sub>), and δ<sup>13</sup>C-CH<sub>4</sub> & δ<sup>2</sup>H-CH<sub>4</sub> of high concentration plumes assist in the identification of emissions, both for major point sources and small leaks from the natural gas distribution system.</p><p> </p><p>Urban focused surveys were conducted in Bucharest during August of 2019. Three continuously-measuring instruments were used, including an LGR Ultraportable CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> analyzer, allowing for the separation of natural gas leaks from other source category emissions. CH<sub>4</sub> and C<sub>2</sub>H<sub>6</sub> 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.  Samples were then analyzed for δ<sup>13</sup>C-CH<sub>4</sub> & δ<sup>2</sup>H-CH<sub>4</sub> 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 CH<sub>4</sub> 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. C<sub>2</sub>:C<sub>1</sub> ratios from specific emissions types were compared with the correlated δ<sup>13</sup>C<sub>CH4</sub> values.</p><p> </p><p>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.</p>

Lime kiln conversion from coke to natural gas operation – an option in direction of sustainable energy

2020 ◽  
pp. 431-434
Author(s):  
Oliver Arndt
Keyword(s):  
Natural Gas ◽  
New Technology ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Gaseous Fuels ◽  
Lime Kiln ◽  
Lime Kilns ◽  
Co2 Balance ◽  
Exhaust Gas Temperature

This paper deals with the conversion of coke fired lime kilns to gas and the conclusions drawn from the completed projects. The paper presents (1) the decision process associated with the adoption of the new technology, (2) the necessary steps of the conversion, (3) the experiences and issues which occurred during the first campaign, (4) the impacts on the beet sugar factory (i.e. on the CO2 balance and exhaust gas temperature), (5) the long term impressions and capabilities of several campaigns of operation, (6) the details of available technologies and (7) additional benefits that would justify a conversion from coke to natural gas operation on existing lime kilns. (8) Forecast view to develop systems usable for alternative gaseous fuels (e.g. biogas).

scholarly journals Responses of Vertebrate Wildlife to Oil and Natural Gas Development: Patterns and Frontiers

2021 ◽  
Author(s):  
A. D. Chalfoun
Keyword(s):  
Natural Gas ◽  
Anthropogenic Activities ◽  
Spatial Scales ◽  
Habitat Type ◽  
Population Level ◽  
Low Frequencies ◽  
Natural Gas Development ◽  
The Usa ◽  
Oil And Natural Gas

Abstract Purpose of Review Anthropogenic activities can lead to the loss, fragmentation, and alteration of wildlife habitats. I reviewed the recent literature (2014–2019) focused on the responses of avian, mammalian, and herpetofaunal species to oil and natural gas development, a widespread and still-expanding land use worldwide. My primary goals were to identify any generalities in species’ responses to development and summarize remaining gaps in knowledge. To do so, I evaluated the directionality of a wide variety of responses in relation to taxon, location, development type, development metric, habitat type, and spatiotemporal aspects. Recent Findings Studies (n = 70) were restricted to the USA and Canada, and taxonomically biased towards birds and mammals. Longer studies, but not those incorporating multiple spatial scales, were more likely to detect significant responses. Negative responses of all types were present in relatively low frequencies across all taxa, locations, development types, and development metrics but were context-dependent. The directionality of responses by the same species often varied across studies or development metrics. Summary The state of knowledge about wildlife responses to oil and natural gas development has developed considerably, though many biases and gaps remain. Studies outside of North America and that focus on herpetofauna are lacking. Tests of mechanistic hypotheses for effects, long-term studies, assessment of response thresholds, and experimental designs that isolate the effects of different stimuli associated with development, remain critical. Moreover, tests of the efficacy of habitat mitigation efforts have been rare. Finally, investigations of the demographic effects of development across the full annual cycle were absent for non-game species and are critical for the estimation of population-level effects.

scholarly journals Observations of Tidal Flat Sedimentation within a Native and an Exotic Spartina Species

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1566
Author(s):  
Barbara Proença ◽  
Florian Ganthy ◽  
Richard Michalet ◽  
Aldo Sottolichio
Keyword(s):  
Single Point ◽  
Field Measurements ◽  
Species Variation ◽  
Storm Events ◽  
Level Variation ◽  
Wave Forcing ◽  
Bed Elevation ◽  
Sediment Stabilization ◽  
Consistent Response

Field measurements of bed elevation and related wave events were performed within a tidal marsh, on two cordgrass species, Spartina anglica (exotic) and Spartina maritima (native), in the Bay of Arcachon (SW France). Bed- and water-level time series were used to infer on the sediment behavior patterns from short to long term. A consistent response was found between the bed-level variation and the wave forcing, with erosion occurring during storms and accretion during low energy periods. Such behavior was observed within the two species, but the magnitude of bed-level variation was higher within the native than the exotic Spartina. These differences, in the order of millimeters, were explained by the opposite allocation of biomass of the two species. On the long term, the sedimentation/erosion patterns were dominated by episodic storm events. A general sediment deficit was observed on the site, suggested by an overall bed-level decrease registered within both species. However, further verification of within species variation needs to be considered when drawing conclusions. Despite possible qualitative limitations of the experimental design, due to single point survey, this work provides original and considerable field data to the understanding the different species ability to influence bed sediment stabilization and their potential to build marsh from the mudflat pioneer stage. Such information is valuable for coastal management in the context of global change.

scholarly journals Air Quality during New Year’s Eve: A Biomonitoring Study with Moss

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 975
Author(s):  
Paweł Świsłowski ◽  
Zbigniew Ziembik ◽  
Małgorzata Rajfur
Keyword(s):  
Heavy Metals ◽  
Air Quality ◽  
Atmospheric Aerosol ◽  
Point Sources ◽  
Accumulation Factor ◽  
Active Biomonitoring ◽  
Aerosol Pollution ◽  
New Year’S Eve ◽  
Short And Long Term

Mosses are one of the best bioindicators in the assessment of atmospheric aerosol pollution by heavy metals. Studies using mosses allow both short- and long-term air quality monitoring. The increasing contamination of the environment (including air) is causing a search for new, cheap and effective methods of monitoring its condition. Once such method is the use of mosses in active biomonitoring. The aim of the study was to assess the atmospheric aerosol pollution with selected heavy metals (Ni, Cu, Zn, Cd, Hg and Pb) from the smoke of fireworks used during New Year’s Eve in the years 2019/2020 and 2020/2021. In studies a biomonitoring moss-bag method with moss Pleurozium schreberi (Willd. ex Brid.) Mitt. genus Pleurozium was used. The research was conducted in the town Prószków (5 km in south direction from Opole, opolskie voivodship, Poland). The moss was exposed 14 days before 31 December (from 17 to 30 of December), on New Year’s Eve (31 December and 1 January) and 2 weeks after the New Year (from 2–15 January). Higher concentrations of analysed elements were determined in samples exposed during New Year’s Eve. Increases in concentrations were demonstrated by analysis of the Relative Accumulation Factor (RAF). The results indicate that the use of fireworks during New Year’s Eve causes an increase in air pollution with heavy metals. In addition, it was shown that the COVID-19 induced restrictions during New Year’s Eve 2020 resulted in a reduction of heavy metal content in moss samples and thus in lower atmospheric aerosol pollution with these analytes. The study confirmed moss usefulness in monitoring of atmospheric aerosol pollution from point sources.

Volume reduction of produced water generated from natural gas production process using membrane technology

2000 ◽  
Vol 41 (10-11) ◽  
pp. 117-123 ◽  
Author(s):  
C. Visvanathan ◽  
P. Svenstrup ◽  
P. Ariyamethee
Keyword(s):  
Natural Gas ◽  
Produced Water ◽  
Hollow Fibre ◽  
Gas Production ◽  
Oil And Grease ◽  
Natural Gas Production ◽  
Pre Treatment ◽  
Selection Of ◽  
Spiral Wound

This paper presents a case study of a natural gas production site covering various technical issues related to selection of an appropriate Reverse Osmosis (RO) system. The long-term field experience indicates the necessity of the selection of appropriate pretreatment systems for fouling-free RO operational conditions. The produced water has a variety of impurities such as oil and grease, process chemicals used for corrosion and scaling control, and dehydration of natural gas, etc. This situation leads to a complicated and extremely difficult task for a membrane specialist to design RO systems, especially the pre-treatment section. Here as part of the pretreatment selection, two types of UF membrane modules viz. spiral wound and hollow fibre, with MWCO of 8000 and 50,000 Dalton respectively, were tested in parallel with NF membranes of the spiral wound type with MWCO 200 Dalton. The UF permeate is used as feed for RO compatibility testing. Both configurations of UF failed to be compatible, due to irreversible fouling of the RO membrane. The NF membrane, however, showed interesting results, due to membrane stability in terms of cleaning and fouling. The NF plant with 50% capacity gave a recovery of 75% and the RO plant gave a recovery of 60% versus the expected 92–95%. The long-term tests have indicated that the reminder of the membranes could be installed to achieve full capacity of the plant. This study also demonstrates the importance of selection of proper pre-treatment set-up for the RO system design.

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