Displays

The worldwide operating petroleum industry is considered as one of the major contributors to global anthropogenic methane emissions. However, not only absolute numbers of methane emissions from oil and natural gas production and distribution vary greatly in different global inventories, also the relative contribution of the oil and the gas sector is under discussion. In different studies, the majority of methane emissions are assigned either to natural gas or to the oil sector. For the climate emission origins are of course irrelevant, however, for the climate budget of natural gas usage it is important to know which emissions are attributable to natural gas and what number is related to oil production with its associated natural gas.

Here we use the Federal Institute of Geosciences and Natural Resources’ (BGR) worldwide database on natural oil and gas production and consumption, dating back to 1900, and compare it to global bottom-up methane emission inventories. We will present and discuss several regression approaches that fit the global data reasonably well. In addition, methane emissions of country groups are compared to natural oil and gas production and consumption data. This study finds that the emission factors that relate to gas production released during oil and gas extraction likely vary over the time and across different production areas in the world.

How to cite: Franke, D., Bahr, A., Gütschow, J., Blumenberg, M., Ladage, S., Lutz, R., and Pein, M.: Attempt to estimate historical methane emissions from the oil and natural gas sector, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4469, https://doi.org/10.5194/egusphere-egu2020-4469, 2020.

The Permian Basin in west Texas and southeast New Mexico (United States) is one of the most productive oil and gas (O&G) basins in the world, but little methane emissions data have been collected from the region.  Environmental Defense Fund (EDF) is leading a year-long science and advocacy campaign to measure O&G methane emissions in the Permian Basin and quickly communicate the data to stakeholders including the public and O&G operators to facilitate emission reductions. EDF and our scientific partners are using three primary approaches to repeatedly quantify emissions at different spatial scales during the campaign. Pennsylvania State University is estimating regional methane emissions on a quarterly basis with atmospheric transport modeling of data collected from a network of five tower-based instruments. University of Wyoming is deploying a mobile laboratory on public roads to measure site-level emissions of methane and volatile organic compounds with EPA Other Test Method 33A and the transect approach.  Scientific Aviation is performing aerial mass balance flights to quantify emissions from small clusters of sites, gridded areas, and larger regions.  Additionally, EDF is collaborating with several groups using remote sensing approaches to quantify methane emissions including TROPOMI, AVIRIS-NG, GAO, and MethaneAIR.  Emissions data including site identities will be published on a custom public website as quickly as possible to educate stakeholders about the magnitude of emissions and facilitate the mitigation of detected emission sources. Following the campaign, data will be analyzed to understand patterns and trends in emissions.  Furthermore, we will discuss the potential for implementing similar monitoring approaches in other O&G basins to provide scientifically-rigorous, actionable data that supports effective mitigation of methane emissions.

How to cite: Lyon, D., Omara, M., Gautam, R., Roberts, K., Trask, B., Leyden, C., Mogstad, I., Zavala-Araiza, D., and Hamburg, S.: Environmental Defense Fund Permian Basin Campaign: a science and advocacy-based approach to quantify and mitigate methane emissions from the oil and gas industry, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11640, https://doi.org/10.5194/egusphere-egu2020-11640, 2020.

Recently, the Aerodyne Mobile Laboratory quantified emissions of methane from oil and gas production sites in two very different oil and gas “plays”. The emission profile of non-methane hydrocarbons shows differences that are associated with the geologic source itself. Further analysis reveals that variations in the non-methane hydrocarbon profile can be exploited to pinpoint the specific piece of equipment that is emitting methane.  The mobile lab was outfitted with tunable infrared laser direct absorption spectrometers and a high resolution Vocus proton transfer reaction mass spectrometer.    This presentation will illustrate the key points with empirical examples and examine methods to attribute observed methane emission sources.      

How to cite: Herndon, S., Daube, C., Krechmer, J., Majluf, F., Fortner, E., Dyroff, C., and Yacovitch, T.: Can non-Methane hydrocarbons inform oil and gas emissions studies?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10810, https://doi.org/10.5194/egusphere-egu2020-10810, 2020.

According to UNFCCC statistics, in 2015 Romania was the country in the European Union that reported the highest emissions of CH₄ from the oil and gas sector to the atmosphere, in particular related to methane production and end use. Limiting these oil and gas-related emissions could provide an attractive greenhouse gas emission reduction target for the EU. However, the reported estimates are derived using standard emission factors and there are only very few observations which investigate whether the reported emissions are realistic. The ROMEO project was designed to provide experimental quantification of methane emissions from the oil and gas sector in Romania. This may strengthen the scientific basis for establishing effective emission mitigation measures. ROMEO is part of the international Climate and Clean Air Coalition's (CCAC's) Methane Science Studies. In August 2019, the first  phase of ROMEO was a city campaign in Bucharest and Ploiesti, where methane emissions were quantified at the street level, using three vehicles. Source attribution was carried out by isotopic analysis and measurement of the ethane-methane ratio. The main ROMEO campaign took place in October 2019, using as campaign base the Strejnicu airfield near Ploiesti. Eight ground measurement teams visited more than 1000 individual facilities and performed methane measurements by stationary and mobile measurements from vehicles, using tracer release approaches and by plume mapping from drones. Very low wind speeds during the campaign period made emission quantification challenging, but about 200 quantifications were attempted. An optical gas imaging team visited many facilities in order to investigate the origin of the emissions at the component scale. Our project partner OMV-Petrom provided information on the facilities and site access where needed. Sites for emissions quantification were selected independent of the operator. To connect the facility scale to the regional scale, two research aircraft from INCAS and Scientific Aviation Inc. performed more than 20 research flights to identify and quantify methane emissions from individual facilities, facility clusters and extended regions. Ground-based in situ and total column measurements provide additional information on the background levels of CH₄. Various models are used for emission quantification, from plume dispersion and mass balance models for individual facilities to atmospheric chemistry and transport models for interpretation of the larger scale aircraft measurements. The final goal of ROMEO is to provide a combined bottom-up and top-down approach to quantify CH₄ emissions related to oil and gas exploration, natural gas distribution and gas use from Romania. I will present the overall setup of the ROMEO project, interesting examples from individual facilities and preliminary results from ground and airborne measurements.

How to cite: Röckmann, T. and the The ROMEO team: ROMEO - ROmanian Methane Emissions from Oil and Gas , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18801, https://doi.org/10.5194/egusphere-egu2020-18801, 2020.

Reducing methane emissions is an important goal of climate change mitigation policies. Recent studies focused on emissions from oil and gas industry, because fixing gas leaks presents a "no-regret" mitigation solution. Yet, uncertainties regarding the fossil fuel emission rates and locations, as well as temporal and spatial variability, are still large for individual source processes, in particular in regions without regular measurements. The Romanian Methane Emissions from Oil and gas (ROMEO) project brought 13 research teams to Romania in order to quantify emissions from this sector. Methane stable isotopes are widely used for source characterisation, but measurement data is lacking from many important geographical locations, such as Eastern Europe. 

A total of 380 air samples were collected in urban areas and around oil and gas extraction sites, from ground level vehicles and from an aircraft. There were measured for δ¹³C-CH₄ and δD-CH₄ using a continuous flow isotope ratio mass spectrometry (CF-IRMS) system. The results were analysed using the Keeling plot approach to derive source signatures at each sampled site. The source signatures obtained for 76 individual oil and gas operation sites range from -70.5 to -22.4 ‰ V-PDB, and from -252 to -144‰ V-SMOW, for δ¹³C and δD respectively. They show a large heterogeneity in δ¹³C, and more regularity in δD values. Variations are affected by the maturity of hydrocarbon deposits, and by different contributions from microbial and thermogenic gas. We will present how the signatures measured at the surface relate to the signatures found for larger plumes sampled from the aircraft. The results of the campaign in Bucharest city reveal a larger contribution from the waste system than fossil fuel fugitive emissions. 

The isotopic characterisation of methane emissions in this region will help to constrain the methane budget on a regional scale, and to improve national inventories.

How to cite: Menoud, M., van der Veen, C., Maazallahi, H., Fernandez, J., Korben, P., Calcan, A., France, J., Lowry, D., Schmidt, M., and Röckmann, T.: Isotopic characterisation of methane emissions from oil and gas operation in Romania, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13643, https://doi.org/10.5194/egusphere-egu2020-13643, 2020.

A wide body of research has characterized methane emissions from the oil and gas supply chain in the US, with recent efforts gaining traction in Canada and Europe. In contrast, empirical data is limited for other significant oil and gas producing regions across the global south. Consequently, measuring and characterizing methane emissions across global oil and gas operations is crucial to the design of effective mitigation strategies.

Several countries have announced pledges to reduce methane emissions from this sector (e.g., North America, Climate and Clean Air Coalition [CCAC] ministers). In the case of Mexico, the federal government recently published regulations supporting a 40-45% reduction of methane emissions from oil and gas. For these regulations to be effective, it is critical to understand the current methane emission patterns.

We present results from multi-scale empirical estimates of methane emissions from Mexico’s major oil and gas production regions (both offshore and onshore), based on a set of airborne-based measurement campaigns, analysis of satellite data (TROPOMI), and development of spatially explicit inventories. Our results provide a revised estimate of total emissions in the sampled regions and highlight the importance of empirically based characterization as a basis for prioritization in terms of emission reduction opportunities.

Finally, we highlight how these measurements –as well as similar policy-relevant studies- connect into action, based on the current needs from relevant stakeholders (e.g., inventory builders, regulators and industry).

How to cite: Zavala-Araiza, D., Omara, M., Gautam, R., Smith, M., Conley, S., Pandey, S., Houweling, S., and Aben, I.: Characterization of methane emissions from oil and gas production in Mexico: Linking measurements to mitigation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16633, https://doi.org/10.5194/egusphere-egu2020-16633, 2020.

The North Sea is home to around 200 offshore platforms that extract oil and natural gas from beneath the sea. Total offshore emissions (carbon dioxide (CO₂), nitrogen oxides (NO + NO₂ = NO_x), nitrous oxide (N₂O), sulphur dioxide (SO₂), carbon monoxide (CO), methane (CH₄) and total VOCs) from upstream oil and gas production in the UK increased by 7 % from 2016 to 2017. Therefore, the accurate measurement and analysis of leakage is critical for global emissions inventories and in terms of mitigating climate change. A recent study (Riddick et al., 2019) showed that on average methane leakage during normal operations is more than double what is reported to the UK National Emissions Inventory (NAEI) for each installation. Here we provide a top-down emissions estimation methodology from which emissions of CH₄ and up to 30 individual volatile organic compounds (VOCs) can be estimated for point-source platforms. We apply a direct integration technique, and use VOC measurements obtained within downwind plumes as a tool for source identification. A total of 16 research flights were conducted as part of a joint project between the UK National Centre for Atmospheric Science (NCAS), BEIS, the UK Offshore Petroleum Regulator for Environment and Decommissioning (OPRED) and Ricardo Energy & Environment to characterise emissions from platforms in the North Sea. The hydrocarbon to ethane enhancement ratio within downwind plumes, measured under well-mixed boundary layer conditions, was used to scale a 1 Hz ethane measurement from the aircraft to other hydrocarbons collected using whole air samplers and measured using GC-FID. This allowed individual VOC emission rates to be calculated and compared to existing inventories. This work highlights how a top down technique can be used to quantify emissions and also provide insight into specific emission sources, in contrast to existing methods which often fail to achieve both simultaneously.

How to cite: Wilde, S., Purvis, R., Lee, J., Hopkins, J., Lewis, A., Young, S., Burton, R., Colfescu, I., Pasternak, D., Mobbs, S., and Bauguitte, S.: A top-down approach for quantifying methane and speciated VOC emissions from North Sea oil and gas facilities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20416, https://doi.org/10.5194/egusphere-egu2020-20416, 2020.

We performed ground-based methane emission measurements (downwind OTM33A method, on site methane measurements) from shale gas production sites in Sichuan province, China (Changning-Weiyuan region, 18 facilities with 81 wells). The mountainous geological location of the sites, and the limited road access has guaranteed only 2 to 3 downwind OTM-33A measurements. A backpack type high-sensitivity methane analyzer was applied to identify methane emissions and map the atmospheric methane distribution inside the gas facilities. The results showed that: the methane level along the fence line of the 16 facilities kept stable at background concentration, with the other 2 enhanced by less than 2 ppm. Inside the 10 facilities putting into production after 2016, pneumatic controllers from the three-phase separator showed no emission since they were running on electricity. Flowback water tanks were the major methane sources with concentration around 354 to 500ppm. Occasionally, the loose venting outlet of the actuator had leakage with methane concentration around 45 ppm. The application of high-sensitivity methane analyzer inside the facility has provided more detailed emission characteristics which could not be found by infrared camera before. This study could provide insights to the emission behavior from components and the distribution patterns of methane inside the shale gas facilities in Sichuan, China. For sites with a non-favored conditions for downwind measurements, other detection methods such as drone-based might be better to implement.

How to cite: Xue, M., Zhao, Y., Fan, J., and Cao, D.: Methane emissions from shale gas production sites in Sichuan, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20729, https://doi.org/10.5194/egusphere-egu2020-20729, 2020.

In July and November 2018 measurements campaigns were performed at the North Sea. This campaign was aimed to assess independently total methane emissions of a selected group offshore oil and gas platforms using concentration measurements at multiple distances from the source in combination with meteorological conditions and dispersion calculations. This measurement set-up is in line with methane measurements carried out near onshore gas production locations in 2016-2017.

First observations with tracer experiments showed different behavior of the plumes offshore, compared to onshore plume behavior.

The Gaussian Plume model was modified with the methodology of the Offshore and Coastal Dispersion (ODC) model, to incorporate the effect of the sea surface and the building effect of the offshore installations on the dilution and mixing of the plume. Together with the performed tracer experiments, this resulted in more reliable calculations of the source strength of methane emissions from the installations.

How to cite: Velzeboer, I., Frumau, A., van den Bulk, P., and Hensen, A.: Methane emission measurements at the North Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19899, https://doi.org/10.5194/egusphere-egu2020-19899, 2020.

Atmospheric methane is the second most important anthropogenic greenhouse gas after carbon dioxide. On the global scale, methane emissions are reasonably well constrained but the contributions from individual sources are highly uncertain (Saunois, 2016). According to bottom-up estimates, methane emissions from underground coal mining excavation contribute 11% to all anthropogenic methane sources (Saunois, 2016). However, there is a lack of in situ measurement to verify these estimates. Here we present results from measurements of the methane mole fraction over the Polish part of the Upper Silesian Coal Basin (USCB). Methane mole fraction was measured using vehicles equipped with high precision laser-based instruments (Picarro G2201-i CRDS, Picarro G2301- CRDS). Basic meteorological data (wind speed, wind direction) and GPS location data were collected on the roof of the vehicles. In order to obtain emission estimates, we attempted to cross the plumes from the coal mine shafts using public roads approximately perpendicular to plume downwind from the source. When possible, the plumes were intersected several times at different distances in order to have a closer look at uncertainties. A Gaussian plume model was used to calculate the release rate from the methane single source.

In addition to methane mole fraction measurements, we collected air samples for isotopic characterization (δ¹³C and δD) using isotope ratio mass spectrometry. We observed significant variation in measured methane isotopic composition over USCB (the results are in a range of -321 to -142 ‰ SMOW for δD and -31 to -58 ‰ VPDB for δ¹³CH₄). The results indicated a much larger variability of the isotopic composition of methane emitted from coal mines than assumed previously, which may complicate the distinction of methane emissions from different sources by isotopic characterization.

Keywords: Methane, Greenhouse Gases, Clime Change, Coal Mine Ventilation Shafts, Methane Isotopic Compositions

Reference:

Saunois, M., Bousquet, P., Poulter, B., et al., 2016a. The global methane budget, 2000–2012. Earth Syst. Sci. Data 8, 697–751. https://doi.org/10.5194/essd-8-697-2016. www.earth-syst-sci-data.net/8/697/2016/.

This work is part of the Marie Sklodowska-Curie Initial Training Network MEMO2 , which enable us to extend these measurements to other European locations

How to cite: Stanisavljevic, M., Nęcki, J., Korbeń, P., Maazallahi, H., Menoud, M., Defratyka, S., Vinkovic, K., van der Veen, C., Chmura, Ł., Zieba, D., Schmidt, M., Wołkowicz, W., Röckmann, T., Wietzel, J., and Swolkień, J.: Methane emissions from coal mines ventilation shafts in Upper Silesia, Poland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15165, https://doi.org/10.5194/egusphere-egu2020-15165, 2020.

The Upper Silesian Coal Basin (USCB) represents one of the largest European CH₄ emission source regions, with a total sum of 500 Gg CH₄/a released by individual coal mine ventilation shafts. During the CoMet (Carbon Dioxide and Methane Mission) campaign in late spring 2018, airborne in-situ measurements were carried out aboard the DLR research aircraft Cessna Caravan. The Cessna was equipped with a cavity ring-down and a quantum cascade laser system to measure CH₄ and CO₂, as well as related tracers such as CO and C₂H₆. Additionally, air samples were collected and analyzed for greenhouse and trace gases, including isotopic ratios of CH₄ and CO₂. Meteorological parameters were measured with a boom mounted sensor package.

During nine research flights, CH₄ emissions were studied by using an airborne Mass Balance Approach. Depending on the wind situation, different areas of the USCB region were targeted. To account for the lower part of the plume not accessible by the aircraft, a number of vans with mobile in-situ measurement systems conducted ground-based measurements in a coordinated manner. The derived methane emission estimate agrees well with bottom-up inventories like the Emission Database for Global Atmospheric Research (EDGAR) and the European Pollutant Release and Transfer Register (E‑PRTR). The CO₂ emission estimate is at the lower end of the inventories. The CO emission estimate is higher than inventory values.

From simultaneous methane and ethane measurement the emission ratios of different subregions of the USCB could be determined. The emission ratios range from 19 to 290 CH₄/C₂H₆ and are, thus, quite variable within this coal basin. From the analysis of collected flask air samples the isotopic composition of CH₄ emissions was determined. Isotopic signatures of Polish USCB CH₄ emissions are between -52.7‰ and -49.4‰ for δ¹³C and between -241‰ and -178‰ for δD. Samples taken in the Czech part of the USCB had a δD isotopic ratio of around -309‰, hinting at a larger influence of biogenic sources in this region.

How to cite: Fiehn, A., Kostinek, J., Eckl, M., Galkowski, M., Chen, J., Gerbig, C., Röckmann, T., Maazallahi, H., Schmidt, M., Korben, P., Necki, J., Wildmann, N., Mallaun, C., Klausner, T., Bun, R., Fix, A., and Roiger, A.: Emissions of CH4, CO2, C2H6, CO and isotopic signatures in the Upper Silesian Coal Basin, Poland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19119, https://doi.org/10.5194/egusphere-egu2020-19119, 2020.

Urban areas are recognised as a significant source of greenhouse gas emissions (GHG), such as carbon dioxide (CO₂) and methane (CH₄). The total amount of urban GHG emissions, especially for CH₄, however, is not well quantified. Here we report on airborne in situ measurements using a Picarro G1301-m analyser aboard the DLR Cessna Grand Caravan to study GHG emissions downwind of the German capital city Berlin. In total, five aircraft-based mass balance experiments were conducted in July 2018 within the Urban Climate Under Change [UC]² project. The detection and isolation of the Berlin plume was often challenging because of comparatively small GHG signals above variable atmospheric background concentrations. However, on July 20^th enhancements of up to 4 ppm CO₂ and 21 ppb CH₄ were observed over a horizontal extent of roughly 45 to 65 km downwind of Berlin. These enhanced mixing ratios are clearly distinguishable from the background and can partly be assigned to city emissions. The estimated CO₂ emission flux of 1.39 ± 0.75 t s^-1 is in agreement with current inventories, while the CH₄ emission flux of 5.20 ± 1.61 kg s^-1 is almost two times larger than the highest reported value in the inventories. We localized the source area with HYSPLIT trajectory calculations and the high resolution numerical model MECO(n) (down to ~1 km), and investigated the contribution from sewage-treatment plants and waste deposition to CH₄, which are treated differently by the emission inventories. Our work highlights the importance of a) strong CH₄ sources in the surroundings of Berlin and b) a detailed knowledge of GHG inflow mixing ratios to suitably estimate emission rates.

How to cite: Klausner, T., Mertens, M., Huntrieser, H., Galkowski, M., Kuhlmann, G., Baumann, R., Fiehn, A., Jöckel, P., Pühl, M., and Roiger, A.: Urban greenhouse gas emissions from the Berlin area: A case study using airborne CO2 and CH4 in situ observations in summer 2018, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3363, https://doi.org/10.5194/egusphere-egu2020-3363, 2020.

Even if methane (CH₄) is one of the most important anthropogenic greenhouse gases, its sources in urban areas are quantitatively highly uncertain. Plant et al. (2019) highlights that current urban inventories probably substantially underestimate real methane emissions. Bottom-up estimates from the German Environmental Agency show uncertainties in urban sources even higher than 300 % (LUBW 2014). Yet for decision makers it is essential to know the strength of potential sources in order to prioritise and perform mitigation actions.

Baden-Württemberg is amongst the regions with the highest estimated methane emission in Germany[i]. Its capital town Stuttgart with more than 600.000 inhabitants is not only the biggest town but also an important industrial centre of the region. As the city centre is located in a deep circular valley the geographical conditions of Stuttgart favour high air pollution and emission stresses. Therefore, the need of emission reduction is strong and of high political interest. Using the example of Stuttgart, this work empirically targets the gap of knowledge about urban methane emission to provide a scientific base for effective local policy measures. More precisely, this study aims to exemplarily quantify typical urban source like waste water treatment plants and natural gas distribution and storage systems in the city of Stuttgart, Germany, by drive-by in-situ measurements and applied plume diffusion models.

Within this study, two optical instruments are used in a mobile setup in a van to measure CH₄, CO₂, H₂O, Ethane and δ¹³CH₄ isotopes: a cavity ring-down spectrometer (CRDS, Picarro G2201-I) and Trace Gas Analyzer (OF-CEAS, LiCor LI-7810). Simultaneous 2D wind data and recorded weather conditions allow the application of dispersion models. Our research group used this technique and successfully tested a gaussian plume model on rural sources like dairy farms around Heidelberg, Germany. With the help of the isotopic composition and the Ethane concentrations, thermogenic sources and biogenic sources can be differentiated.

In August and December 2019, two short campaigns have been performed to identify potentially big sources in Stuttgart. The wastewater treatment plant in Mühlhausen and the natural gas storage facility in Gaisberg have been selected as representative targets. A next campaign is planned in spring 2020, including probably 3D-wind measurements and elaborated dispersion models. By taking advantage of inversion weather conditions, which are typical for Stuttgart, mass balance models can possibly be applied. So far, the results promise to allow quantifying emission rates of the target sources.

How to cite: Nelson, C., Schmidt, M., Butz, A., and Roiger, A.: Quantifying urban methane emissions in the city of Stuttgart, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4611, https://doi.org/10.5194/egusphere-egu2020-4611, 2020.

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 (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.  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 CH₄ and ethane (C₂H₆), and δ¹³C-CH₄ & δ²H-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.

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.  Samples were then analyzed for δ¹³C-CH₄ & δ²H-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 δ¹³C_CH4 values.

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.

How to cite: Fernandez, J., France, J., Menoud, M., Maazallahi, H., Corbu, M.-P., Röckmann, T., Fisher, R., and Lowry, D.: Characteristics of urban street level methane emissions in Bucharest, Romania, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21759, https://doi.org/10.5194/egusphere-egu2020-21759, 2020.

Although anthropogenic emissions of trace gases have decreased over the last decades in Europe, strong additional reductions are required to reach the goals of the Paris climate agreements. In addition, air pollution is an issue of great concern for the inhabitants of the metropolitan area of Bucharest, as the local air quality is often poor. The rapid development of the city, increased traffic volume from a mixed vehicle fleet (different technologies and fuels), and other factors are strong contributors of emissions of greenhouse gases and air pollutants in Bucharest.

The goal of this research was the assessment of CO, CO₂ and CH₄ concentrations in Bucharest, identification of potential emissions hotspots and their causes (anthropogenic or natural/biogenic, local or distant) and determination of the background values.

Measurements were performed in summer 2019 in four districts of Bucharest covering about two thirds of the metropolitan area during the Romanian Methane Emissions from Oil&gas (ROMEO) campaign with high resolution (1 sec). These data sets were complemented with satellite observations of CO and CH₄ from Copernicus Sentinel-5P at a resolution of 7 km².

Hourly meteorological data, temperature, relative humidity, wind speed and direction, and atmospheric pressure were added to the air pollutant data set because synoptic conditions can strongly influence the levels of pollution. Air mass origins were investigated by computing backward air mass trajectories using the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model for 72 hours back.

Points of high concentrations of CO, CO₂, CH₄ near the surface were identified which are, most likely, linked to local anthropogenic activities in the nearby surroundings. We identified a variation of concentrations of CO from 0.01 to 101 ppm, of CO₂ from 388 to 6556 ppm, and of CH₄ from 1.89 to 246 ppm, while background levels are as follows: 0.071±0.042 ppm CO, 392.68±3.01 ppm CO₂, and 1.93±0.016 ppm CH₄.

Results of our study provide an up to date quantitative image of CO, CO₂, CH₄ hotspots in the Bucharest area, which is important for modeling air quality and may also help to improve the relationships between column integrated air pollution data with in situ ground observations.

Acknowledgement:

This research is supported by ROMEO project, developed under UNEP’s financial support PCA/CCAC/UU/DTIE19-EN652. Partial financial support from UB198/Int project is also acknowledged.

The authors acknowledge the free use of tropospheric CO and CH₄ column data from TROPOMI (Sentinel-5P) sensor from https://s5phub.copernicus.eu and the NOAA Air Resources Laboratory for the provision of the HYSPLIT transport model available at READY website https://www.ready.noaa.gov

Special thanks to all INCAS technical staff for their support in performing the campaigns.

How to cite: Corbu, M.-P., Calcan, A., Vizireanu, I., Moaca, D. E., Chiritescu, R.-V., Roeckmann, T., Maazallahi, H., Fernandez, J. M., France, J., and Iorga, G.: Atmospheric satellite-based and in situ surface observations on summertime trace gases (CO, CO2, CH4) over the metropolitan area of Bucharest, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4930, https://doi.org/10.5194/egusphere-egu2020-4930, 2020.

Despite the Paris Agreement, greenhouse gas (GHG) concentrations in the atmosphere continue to increase because of the anthropogenic activities, and this is inducing catastrophic effects. Past studies revealed that urban areas are responsible of a large part of these emissions and many cities already started to implement climate actions to reduce their GHG emissions and address climate change. The effectiveness of these actions depends on accurate knowledge of the many sources of GHG in each city, so that efforts are focused on the sources whose emission reduction would be the most effective. Atmospheric measurements are useful to locate and characterize these sources and to monitor the evolution of their emissions. Different approaches have been developed during the past decades including stationary and mobile surface-based in situ measurements, remote sensing of solar absorption spectra from space and from the ground, or aircraft-based observations. All these techniques are complementary and provide information about urban GHG emissions at different scales.

In situ mobile measurements of methane mixing ratios have been performed in the two largest cities of Canada using 1) a high-precision gas analyzer providing continuous measurements, 2) a weather station measuring wind speed and direction, and 3) a GPS recording coordinates during the campaigns. These mobile surveys allow rapid screening of large areas, the revisit of specific sites to monitor the evolution of their emissions over time, and can therefore improve our understanding of the emissions at local scale. Methane emissions of the Greater Toronto Area (GTA) have been intensively investigated since 2018 with a total of 84 days of measurements corresponding to a distance of about 8,000 km. A one-week campaign has also been realized in November 2019 in Montreal corresponding to a distance of about 1,100 km. Methane enhancements observed during these surveys have been identified, classified into three categories depending on their magnitudes and areas, and attributed to potential sources, several of which are not catalogued in FLAME-GTA, the point source level inventory developed for the Toronto metropolitan area. Important methane sources in the GTA have been surveyed regularly since 2018 and their emissions have been estimated using an inverse modeling framework with a Gaussian model and compared to the inventory-based estimates of FLAME-GTA.

How to cite: Ars, S., Wunch, D., Ajmeri, T., Arrowsmith, C., Beauregard, G., Cruz, R., Gillespie, L., Heerah, S., Knuckey, E., Lavoie, J., Macdonald, C., Mostafavi Pak, N., Nguyen, S., Phillips, J. L., and Vogel, F.: Using atmospheric in situ mobile measurements to monitor urban methane emissions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19995, https://doi.org/10.5194/egusphere-egu2020-19995, 2020.

Changes in atmospheric methane (CH₄) are mainly driven by natural, anthropogenic and pyrogenic emissions and oxidation by OH.

There is no consensus about the underlying explanations about hemispheric-scale changes in atmospheric methane (CH₄). This is partly due to sparse data that do not exclusively identify individual changes in surface emissions and surface and atmospheric losses of CH₄. This challenge represents a major scientific weakness in our understanding of this potent greenhouse gas, with implications for meeting global climate policy obligations.  A confounding challenge is that the regional importance of individual emission sources change with time due to, for example, innovations in agricultural practices, climate-sensitive wetlands, and political decisions associated with climate friendlier transitional fuels.  

Here we use bulk isotope ratios δ¹³C and δD of CH₄ that have been previously shown to provide effective constraints on source apportionment: different CH₄ sources have characteristic isotope ratios. One of the key challenges associated with using these data is that region-specific isotope ratios change with time due to varying source prevalance, in addition to source signatures having inherent uncertainties. We use the GEOS-Chem global 3-D chemical transport model to describe the spatial and temporal isotopic behaviour of atmospheric CH₄. We develop a Maximum A-Posteriori inverse method to simultaneously infer time dependent CH₄ emissions and isotope ratios from in situ data. 

We will report the magnitude, distribution and source attribution of CH₄ emissions from 2004 to 2017, inferred from in situ measurements of total atmospheric CH₄ mole fraction and the corresponding measurements of δ¹³C and δD. We will compare our results with previous studies.

How to cite: Drinkwater, A., Arnold, T., and Palmer, P.: Global Methane Emissions Through an Isotopic Lens, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-745, https://doi.org/10.5194/egusphere-egu2020-745, 2020.

Methane is the second most important anthropogenic greenhouse gas. The globally averaged dry mole fraction has increased considerably since pre-industrial times and its growth even accelerated in 2014, with an annual rise of 12.7 ± 6 ppb. Fossil fuel emissions are one of the primary sources. However, the quantification of methane sources and sinks is still under debate and estimates of anthropogenic emissions show large uncertainties on global and regional scales. Comprehensive measurement campaigns, such as CoMet 1.0 (May-June 2018), are therefore important for assessing climate change mitigation options. CoMet aimed to quantify point source emissions in the Upper Silesian Coal Basin (USCB), where roughly 502 kt/yr of methane are emitted due to coal mining. Differences in isotopic methane source signatures δ¹³C and δD can further help to constrain different source contributions (e.g. thermogenic or biogenic). We simulate methane isotopologues from localized coal mine emissions in the USCB using the on-line three times nested global regional chemistry climate model MECO(n). We use a submodel extension, which includes the kinetic fractionation and make different assumptions on the isotopic source signatures in the USCB. Here we show first results of these simulations and a comparison to flask samples taken during CoMet 1.0.

How to cite: Nickl, A.-L., Winterstein, F., Mertens, M., Kerkweg, A., Fiehn, A., Gerbig, C., Galkowski, M., and Jöckel, P.: Simulation of methane point source emissions and their isotopic signatures using the global/regional climate model MECO(n)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18829, https://doi.org/10.5194/egusphere-egu2020-18829, 2020.

Reaching the targets of the Paris Agreement requires massive reductions of greenhouse gas emissions. CH₄emissions are a major contributor to Europe’s global warming impact and emissions are not well quantified yet. There are significant discrepancies between official inventories of emissions and estimates derived from direct atmospheric measurement. Effective emission reduction can only be achieved if sources are properly quantified, and mitigation efforts are verified. New advanced combinations of measurement and modelling are needed to archive such quantification.

MEMO²is a European Training Network with more than 20 collaborators from 7 countries. It is a 4-years project and will contribute to the targets of the EU with a focus on methane (CH₄). The project will bridge the gap between large-scale scientific estimates from in situmonitoring programs and the ‘bottom-up’ estimates of emissions from local sources that are used in the national reporting by I) developing new and advanced mobile methane (CH₄) measurements tools and networks, II) isotopic source identification, and III) modelling at different scales. Within the project qualified scientists will be educated in the use and implementation of interdisciplinary knowledge and techniques that are essential to meet and verify emission reduction goals. MEMO²facilitates intensive collaboration between the largely academic greenhouse gas monitoring community and non-academic partners who are responsible for evaluating and reporting greenhouse gas emissions to policy makers.

We will present the project, its objectives and the results so far to foster collaboration and scientific exchange.

How to cite: Walter, S. and Röckmann, T. and the MEMO2 team: MEMO2: MEthane goes MObile – MEasurements and Modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6760, https://doi.org/10.5194/egusphere-egu2020-6760, 2020.

The final course of the Llobregat river (south-west of Barcelona, Spain) is surrounded by densely populated cities, industrial areas and agricultural lands. Multiple water infrastructures where anaerobic processes may be expected are present in the basin: three wastewater treatment plants, a drinking water treatment plant, several irrigation channels and a desalination plant. Other likely methane emission infrastructures as waste processing plants or gas refilling stations are present, together with natural methane potential sources as wetlands.

Multiple mobile measurements were performed during 2019 along the final course of the Llobregat basin to study the variability of methane emissions throughout the year. The surveys were carried out in different days at different times with a car equipped with a flight-ready CO2/CH4/H2O cavity ring-down spectrometer.

Emissions of different infrastructures and its variability throughout the year has been determined using a statistical approach from the georeferenced data. Local winds and plume modeling has been used to better pinpoint the sources and estimate the emissions. Finally methane concentrations and emissions variability have been related with meteorological factors as temperature or pressure. These factors, together with human-related management of the water infrastructures, may drive the methane emissions significantly far from inventory estimations.

How to cite: Curcoll, R., Estruch, C., Freixas, J., and Morgui, J.-A.: Methane emission rates from water infrastructures derived from mobile surveys along the final course of the Llobregat basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9673, https://doi.org/10.5194/egusphere-egu2020-9673, 2020.

Last year we described the campaign and the first results (Kelly et al., 2019; Neininger et al., 2019).

This year we will give an update on methods applied for estimating the regional methane emissions on a scale of about 10'000 km², and sub-regions of about 2'500 km².

Two approaches were applied:

1. The classical mass balance, where the inflow and the outflow of an imaginary box was calculated, based on almost perfect Lagrangian cross-sections (following the air mass).
2. A mass balance for the part of the boundary layer, where flight tracks were available (below 300 m above ground), supplemented by vertical turbulent fluxes to above this height.

In the best case, the two methods are leading to similar emission rates. The advantage of method (2) is, that the long flight legs can be limited to the lower boundary layer, which is especially useful when a convective boundary layer is reaching up to typically 2 km or higher above the surface.

The method worked quite well for water vapour, CO₂ and sensible heat, where fully resolved turbulent fluxes could be calculated based on 10 Hz measurements along the flight legs. Since CH₄ could only be measured with a temporal resolution of about two seconds (0.5 Hz), these a-priori results of the turbulent vertical fluxes are less consistent. However, by applying factors of turbulent versus advective fluxes from the other species, the agreement between the two methods was improved. The turbulent transport to above the 300-metre-layer during the convective conditions was about equal to the accumulation in this layer.

Since estimating the height of the convective boundary layer and the assumption that the mixing is perfect for approach (1) has many limitations, using method (2) has the advantage that less assumptions on homogeneity of the atmosphere above the densely observed layer has to be made. Even when the concentration profiles and the wind are known from vertical soundings (excursions to above the convective boundary layer), the horizontal inhomogeneity remains unknown. When using the vertical turbulent fluxes into this unknown volume above the lower layer, inhomogeneous mixing is not a problem.

The challenge of method (2) is to measure fast and precise enough for the quantification of the vertical fluxes. When concentrating on this, one could save time by omitting high soundings, improving the horizontal coverage, and therefore the statistics for the vertical fluxes.

References

Kelly et al.: Direct Measurement of Coal Seam Gas and Agricultural Methane Emissions in the Surat Basin, Australia. EGU 2019.

Neininger, B., J. M. Hacker and W. Lieff: Airborne Measurements for estimating Methane Emissions in the Surat Basin, Australia. EGU 2019.

How to cite: Neininger, B., Hacker, J. M., and Lieff, W.: Estimating Methane Emissions in the Surat Basin, Australia, including turbulent vertical Fluxes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10993, https://doi.org/10.5194/egusphere-egu2020-10993, 2020.

One of the case study sites for the Climate and Clean Air Coalition (CCAC) Methane Science Studies is the coal seam gas (CSG) field in the Surat Basin, Queensland, Australia, where there are over 6000 CSG wells and associated gas and water processing infrastructure. Previous bottom-up estimates suggest that the major source of methane in the region is cattle, not CSG (Katestone, 2018, Luhar et al. 2018).

In September 2018, an airborne measurement campaign was undertaken to provide a top-down estimate of regional methane emissions. Modelling of the airborne methane mole fraction data has produced a defensible total methane emissions estimate. However, there are challenges with proportioning the top-down estimates provided by the airborne data, because of adjacent sources with similar d¹³C-CH₄ isotopic chemistry, rapid mixing of adjacent sources and substantial dilution of the plumes at the airborne measurement sampling height. We present how we will overcome these challenges.

At each gas production well, tens of thousands of litres of water are produced daily in association with the methane extracted from the coal measures. This water is stored in ponds and is also used as a water supply for cattle feedlots, which are located throughout and adjacent to the CSG wells and processing facilities. Power stations are also located within the CSG field. This arrangement makes it challenging to obtain clean top-down estimates of the emissions from CSG production. Quantifying methane emissions associated with CSG production is further complicated by numerous other sources of methane in the region immediately adjacent to the CSG field. These sources include grazing cattle, abattoirs, more power production facilities, coal mines, wetlands, natural gas seeps, and small urban centres with associated sewage treatment plants and landfills. Grab bag air samples were collected at each of these sources and analysed for d¹³C-CH_4, d¹³C-CO₂ and dD-CH₄.

The airborne measurement campaign was undertaken under warm daytime spring conditions. This caused rapid uplift and mixing of the methane plumes. The maximum difference between the lowest and highest methane mole fraction from 90 airborne collected grab bag air samples was only 0.03 ppm. Even at this low mole fraction, by implementing quality management protocols we were able to extract trends in the isotope data sets. This presentation will outline the quality management procedures and how the measurements of d¹³C-CH_4, d¹³C-CO₂ and dD-CH₄ will be used to assist with methane source attribution.

Reference

Katestone Environmental Pty Ltd (2018) Surat Basin Methane Inventory 2015 - Summary Report. Prepared for CSIRO March 2017 (D15193-11).

Luhar, A., Etheridge, D., Loh, Z., Noonan, N., Spencer, D., Day, S. (2018). Characterisation of Regional Fluxes of Methane in the Surat Basin, Queensland. Final report on Task 3: Broad scale application of methane detection, and Task 4: Methane emissions enhanced modelling. Report to the Gas Industry Social and Environmental Research Alliance (GISERA). Report No. EP185211, October 2018. CSIRO Australia.

How to cite: Lu, X. (., Harris, S. J., Fisher, R. E., Lowry, D., France, J. L., Hacker, J., Neininger, B., Röckmann, T., van der Veen, C., Menoud, M., Schwietzke, S., and Kelly, B. F. J.: Methane Source Attribution Challenges in the Surat Basin, Australia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12508, https://doi.org/10.5194/egusphere-egu2020-12508, 2020.

Methane is assumed to belong to the most  important greenhouse gases, however factors affecting methane production and emission are still not satisfactory elucidated. Artificial reservoirs which are critical resources to obtain water and hydropover in many countries are  one of the methane sources which received only limited attention so far.   We reviewed existing information about methane emissions from them.  Emissions  are combination of diffusion, ebullition and degassing under dam, but not all pathway must be presented. Nineteen studies, mainly from North America and Europe were compared, Only small portion of the studies was focusing on all pathways of methane release. Spatio-temporal variability, which is especially high for ebullition (ebullition is probably responsible for the most of the methane emissions), was covered in 3 reservoirs only. For this purposes is newly used acoustical method good tool, hydroacoustics cover mainly spatial variability of ebullition, which is poorly couth by traditional bubble traps. The most of the  studies was performed in summer period only and for low number of localities.  Future studies should use more uniform design covering better all potential pathway of methane emissions and  taking care of spatio-temporal variability of ebullition.  More systematic studies covering effect of climate and landscape variables as well as reservoir properties (morphology management etc.) are needed.

How to cite: Frouzova, J. and Bašta, J.: Emissions of methane from temperate artificial reservoirs – what is already known, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13176, https://doi.org/10.5194/egusphere-egu2020-13176, 2020.

Methane from facility-scale sources (e.g. landfills and oil and gas production facilities) are prone to leakage giving rise to highly uncertain emission flux estimates. To assess the overall impact of these sources, quantification from a representative set of individual sources – from which bottom-up inventories are generated - is necessary. An attractive approach to quantify emissions from diffusive and leaky sources involves deploying an unmanned aerial vehicle (UAV) equipped with a methane sensor which allows complete mapping of the spatial and temporal variability of emission plumes within a short period of time.

Atmospheric methane concentrations were measured using a Quantum Cascade Laser Absorption Spectrometer (QCLAS) developed in-house. The spectrometer reaches in-flight precision of a few ppb at 1s time resolution, and its lightweight and compact footprint (~ 2.0 kg, ~ 15.0 x 45.0 x 25.0 cm) allows it to be mounted and flown on a commercial drone.

We quantify methane emission fluxes from local sources by applying the mass balance method using the drone-based QCLAS system. The drone was flown downwind of a given source perpendicular to the main wind direction at different altitudes above ground, while geostatistical interpolation (Kriging) of the measured methane molar fractions was performed to spatially fill the gaps. The interpolated concentrations were multiplied by the cross-sectional area and the mean stream-wise wind profile obtained from a 3D sonic anemometer to get an emission flux.

We report on the analysis of how well known emissions can be reproduced using this quantification setup based on controlled release experiments. Furthermore, we discuss the sensitivity of different measurement configurations, and provide recommendations for an optimal sampling and quantification strategy. We demonstrate the suitability and flexibility of the quantification method in investigating a wide range of facility-scale sources, which are not attainable with measurements from conventional ground-based sensors.

How to cite: Morales, R. P., Ravelid, J., Brennan, K. P., Tuzson, B., Emmenegger, L., and Brunner, D.: Estimating local methane sources from drone-based laser spectrometer measurements by mass-balance method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14778, https://doi.org/10.5194/egusphere-egu2020-14778, 2020.

Emissions of methane from combustion sources are typically distinguished by being enriched in ¹³C and ²H, causing a large isotopic shift to atmospheric methane δ¹³C and δD measurements downwind of fires.

The isotopic composition of the plant material being burnt has a strong effect on the isotopic composition of methane, with combustion of C4 plant material producing methane more enriched in ¹³C than C3 plant combustion. Characterisation of the bulk isotopic signature of methane emitted from large areas of biomass burning is required to improve our ability to use isotopes in global models and ascertain the extent to which fire emissions influence interannual variations in the methane budget.

Two approaches have been used to collect air samples from large areas of biomass burning for isotopic characterisation of methane emitted from the fires. In campaigns in Senegal, Uganda, Zambia and Finland, the UK’s FAAM research aircraft flew through fire plumes and onboard measurement of methane concentration allowed targeted sampling within the plumes. This work was carried out as part of the NERC highlight Global Methane Budget project (MOYA). Ground based sampling downwind of fires around Sydney, New South Wales in late 2019/early 2020 has allowed isotopic characterisation of those plumes. All air samples were measured by isotope ratio mass spectrometry at Royal Holloway University of London and Keeling plots used to identify source signatures, e.g. δ¹³C for fires in Senegal in March 2017 was -28.5 ± 0,8 , typical of C3 burning.

In this work we compare the isotopic signatures of methane from burning in these particular regions and discuss the extent to which the regional variability of the isotopic composition of fire emissions should be taken into account in global models using isotopes to constrain the global methane budget.

How to cite: Fisher, R., Nisbet, E., France, J., Riddle, A., Lowry, D., Lanoiselle, M., Lu, X., and Kelly, B.: Improved isotopic characterisation of methane emissions from biomass burning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17468, https://doi.org/10.5194/egusphere-egu2020-17468, 2020.

Methane (CH₄) is an important greenhouse gas, and is increasing in the atmosphere by 0.6% (10 ppb) each year. Important sources of this gas are landfills; in fact more than 10% of the total anthropogenic emissions of CH₄ are originated in them by anaerobic degradation of organic matter. Even after years of being closed, a significant amount of landfill gas can be released to the atmosphere through its surface as diffuse or fugitive degassing.

Many landfills currently report their CH₄ emissions to the atmosphere using model-based methods, which are based on the rate of production of CH₄, the oxidation rate of CH₄ and the amount of CH₄ recovered (Bingemer and Crutzen, 1987). This approach often involves large uncertainties due to inaccuracies of input data and many assumptions in the estimation. In fact, the estimated CH₄ emissions from landfills in the Canary Islands published by the Spanish National Emission and Pollutant Sources Registration (PRTR-Spain) seem to be overestimated due to the use of protocols and analytical methodologies based on mathematical models. For this reason, direct measurements to estimate CH₄ emissions in landfills are essential to reduce this uncertainty.

In order to estimate the CH₄ emissions to the atmosphere from landfills in the Canary Islands, 34 surveys have been performed since 1999 to the present. Each survey implies hundreds of CO₂ and CH₄ efflux measurements covering the landfill surface area. Surface landfill CO₂ efflux measurements were carried out at each sampling site by means of a portable non-dispersive infrared spectrophotometer (NDIR) model LICOR Li800 following the accumulation chamber method. Samples of landfill gases were taken in the gas accumulated in the chamber and CO₂ and CH₄ were analyzed using a double channel VARIAN 4900 micro-GC. The CH₄ efflux measurement was computed combining CO₂ efflux and CH₄/CO₂ ratio. To quantify the diffuse or fugitive CO₂ and CH₄ emission, gas efflux contour maps were constructed using sequential Gaussian simulation (sGs) as interpolation method. Considering that (a) there are 6 controlled landfills in the Canary Islands, (b) the average area of the 34 studied cells is 0.15 km² and (c) the mean value of the CH₄ emission estimated for the studied cells range between 6.2 and 7.2 kt km^-2 y^-1, the estimated CH₄ emission to the atmosphere from landfills in the Canary Islands showed a range of 5.7-6.7 kt y^-1 (mean value of 6.2 kt y^-1). On the contrary, and for the same period of time, the PRTR-Spain estimates the CH₄ emission in the order of 6.4-16.4 kt y^-1 (mean value of 9.2 kt y^-1), nearly 46% more than our estimated value. This result demonstrates the need to perform direct measurements to estimate the surface fugitive emission of CH₄ from landfills.

Bingemer, H. G., and P. J. Crutzen (1987), J. Geophys. Res. 92, 2182-2187.

How to cite: Padrón, E., Asensio-Ramos, M., Pérez, N. M., Di Nardo, D., Albertos-Blanchard, V. T., Alonso, M., Tassi, F., Raco, B., and López, D.: Methane emission to the atmosphere from landfills in the Canary Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5651, https://doi.org/10.5194/egusphere-egu2020-5651, 2020.

Mitigation of climate change is a key scientific and societal challenge. CH₄ emissions are a major contributor to global warming impact and these are not well quantified yet. There are significant discrepancies between official inventories of emissions and estimates derived from direct atmospheric measurement. Effective emission reduction can only be achieved if sources are properly quantified, and mitigation efforts are verified.

CH₄ from waste is dominantly of biogenic origin and its levels can vary with temperature and production process, which results in variation of emissions with time of day and time of year. Selected waste streams are now commonly sent to biogas plants, where the waste is digested to produce methane, which may be utilised directly, or combusted to provide power. Different waste streams, such as maize stubble or paper products, are characterized by distinct δ¹³C-CH₄ signatures.  Emissions from each stage of the biogas production process can be identified by analysing the methane isotopic composition.

This study focuses on identification and quantification of CH₄ emissions from waste sources in the UK from 2018-2020 using laser-based mobile surveys downwind of landfills, biogas plants and wastewater treatment plants. Air samples were collected and analysed for isotopic characterization using high precision Gas Chromatography Isotopic Ratio Mass Spectrometry. Survey data were used to map concentration excess over background, identify isotopic composition and estimate fugitive emissions from selected sources.

Average carbon isotopic signatures for new data on methane sources in the UK are -53 ‰ for wastewater treatment plants and -55 ‰ for biogas plants. CH₄ emissions range from 6.2 to 50 g/h depending on size and operating conditions of plants. Also, isotopic signature of methane emission from active sites in the landfill are in the range -60 to -58 ‰ with 2 - 10% oxidation rate, which is characteristically more depleted than closed sites.

How to cite: Bakkaloglu, S., Lowry, D., Fisher, R., France, J., Lanoiselle, M., and Fernandez, J.: Characterization and Quantification of Methane Emissions from Waste in the UK, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17839, https://doi.org/10.5194/egusphere-egu2020-17839, 2020.

Quantification of gaseous emissions from waste water treatment plants (WWTPs) is challenging due to the heterogeneity of the emissions in space and time. The inverse dispersion method (IDM) using concentration and turbulence measurements in combination with a backward Lagrangian stochastic (bLS) dispersion model based on Flesch et al. (2004) is a promising option. It is  increasingly used to determine gaseous emissions from confined sources (Flesch et al., 2009; VanderZaag et al., 2014), as it offers high flexibility at reasonable costs. For the application on WWTPs the bLS model assumption of spatially homogeneous turbulence, which implies absence of obstacles as buildings and trees that disturbe the flow, is often not fulfilled. However, studies showed that with the correct instrument setup and data filtering the bLS can be used for emission estimates. Methane emissions from two WWTPs of different type and size were quantified using the IDM with the bLS model. Methane concentrations were analysed with open-path tunable diode laser spectrometers (GasFinder, Boreal Laser, Inc., Edmonton, Alberta, Canada) placed up- and downwind of the source. At each site at least 20 days of measurements averaged to 30-minutes intervals are available. Here we present first results from these two WWTPs emission estimates.

References

Flesch, T. K., Wilson, J. D., Harper, L. A., Crenna, B. P., and Sharpe, R. R.: Deducing ground-to-air emissions from observed trace gas concentrations:
A field trial, J. Appl. Meteorol., 43, 487–502, doi:10.1175/1520-0450(2004)043<0487:DGEFOT>2.0.CO;2, 2004.

Flesch, T. K., Harper, L. A., Powell, J. M., and Wilson, J. D.: Inverse-dispersion calculation of ammonia emissions from Wisconsin dairy farms, Trans. ASABE, 52, 253–265, doi:10.13031/2013.25946, 2009.

VanderZaag, A. C., Flesch, T. K., Desjardins, R. L., Baldé, H., and Wright, T.: Measuring methane emissions from two dairy farms: Seasonal and manure-management effects, Agricultural and Forest Meteorology, 194, 259–267, doi:10.1016/j.agrformet.2014.02.003, 2014.

How to cite: Bühler, M., Häni, C., Kupper, T., Ammann, C., and Brönnimann, S.: Quantification of methane emissions from waste water treatment plants, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13389, https://doi.org/10.5194/egusphere-egu2020-13389, 2020.

One of the largest methane anthropogenic sources worldwide is livestock production. In Denmark, this contribution reached 81.1% of total anthropogenic methane, divided into both enteric fermentation and manure management emissions (Nielsen et al., 2019). Numerous factors can influence methane emissions from livestock production. The development of strategies to measure and monitor this anthropogenic activity allows the identification of efficient mitigation actions. The dynamic tracer gas dispersion method (TDM) is a ground-based remote sensing method, which combines a controlled release of tracer gas from the target source with concentration measurements downwind of the same source. TDM has been compared to other remote sensing techniques and widely applied for methane quantification from many facilities (Samuelsson et al., 2018). Previous studies found that this method is very likely to reached up to only 20% of error (Fredenslund et al., 2019). For livestock methane quantification, TDM has been used before releasing a strong greenhouse gas (SF₆) with mostly stationary point sampling setup. The aim is to verify the suitability of the method for these facilities and identify the differences between farming approaches. Furthermore, the comparison of the measured emissions with inventory estimation could show the accuracy of the later.

This study uses acetylene as tracer gas and measurements performed with a fast responding and highly sensitive gas analyzer by Picarro. On this project, emissions from six livestock facilities (dairy cows and swine production) were investigated along one year.

Dairy farms were the largest methane emitters per head (Around 40 gCH₄/head/h). Results show that management practices might cause different methane emissions from dairy farms. Similar result was observed analyzing emissions from pig facilities (Around 6 gCH₄/head/h), with an influence of animal life stage. The sow’s farm had the highest methane emission factor when compared to fattening pigs, while manure acidification treatment might have a positive impact on reducing methane emission.

The successful application in this study of the TDM showed that this method is a valuable tool to support Danish farming strategies to meet ambitious GHG emission reduction targets.

Fredenslund, A. M., Rees-White, T. C., Beaven, R. P., Delre, A., Finlayson, A., Helmore, J., … Scheutz, C. (2019). Validation and error assessment of the mobile tracer gas dispersion method for measurement of fugitive emissions from area sources. Waste Management, 83, 68–78.

Nielsen, O.-K., Plejdrup, M. S., Winther, M., Nielsen, M., Gyldenkærne, S., Mikkelsen, M. H., … Hansen, M. G. (2019). Denmark’s National Inventory Report 2019 (Emission I).

Samuelsson, J., Delre, A., Tumlin, S., Hadi, S., Offerle, B., & Scheutz, C. (2018). Optical technologies applied alongside on-site and remote approaches for climate gas emission quantification at a wastewater treatment plant. Water Research, 131, 299–309.

How to cite: dos Reis Vechi, N., Delre, A., and Scheutz, C.: Assessment of methane emissions from Danish livestock production practices using a tracer gas dispersion method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20405, https://doi.org/10.5194/egusphere-egu2020-20405, 2020.

The three major anthropogenic CH₄ (methane) sources in Germany are ruminants (53%), waste and waste water treatment (22%) and transport and storage of natural gas (25%). In order to quantify these emissions on a facility scale, we used a CH₄ analyser installed in vehicle. Mobile measurements are performed on regular campaigns including measurements of the concentration and isotopic composition of methane. During this study we visited  11 times a Dairy Farm in Weinheim, north of Heidelberg. The farm has a livestock of about 320 - 340 dairy cows with an average milk production of 29 l per cow and day. A biogas plant is located next to the cowshed. To determine the temporal and spatial variability of emissions, collected data are analysed with Gaussian plume model to obtain emissions from dairy cows and biogas plant. For each mobile measurements campaign, we analysed 10 -40  transects (driving the car forward and backward). The first estimations of the emissions  (cows and biogas included) shows strong variabilities and up to 8 times higher values, than expected when comparing to IPCC reported emission values for dairy cows . As our measurements represent the whole farm emission, including  biogas plant and liquid manure, we have to distinguish these sources and quantify the contribution of each. .

How to cite: Korben, P., Kammerer, J., Wietzel, J., and Schmidt, M.: Methane emission from dairy farm located in north of Heidelberg, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20442, https://doi.org/10.5194/egusphere-egu2020-20442, 2020.