Measurement of methane emissions from confined sources using the inverse dispersion method

Greenhouse gas (GHG) emissions are reported in annual national inventories. Globally, the main anthropogenic sources of methane (CH4) are fossil fuel burning, agriculture, landfills, and waste management. The main source of CH4 from agriculture is enteric fermentation in the digestive tract of ruminants and a minor source are emissions from manure management. In 2019, the Swiss Federal council decided that Switzerland must reduce its GHG emission to net-zero until 2050. To reach this goal, the agricultural sector is obliged to contribute to the emission reduction. However, emissions from the agriculture and waste sector imply large uncertainties as, among other reasons, the availability of data based on real-world studies is limited. Several investigations showed that measurements from laboratory- or pilot-scale experiments do often not comply with real-world conditions. For studies under real-world conditions, different measurement approaches are available. One of the most promising methods is the inverse dispersion method (IDM) that was applied in this thesis to measure CH 4 emissions from livestock production and the waste management sector in order to evaluate the method for complex source configurations and to specify emission factors of these sources. For the IDM, a backward Lagrangian stochastic (bLS) model in combination with concentration measurements up- and downwind of the source using open-path tunable diode laser spectrometers (GasFinders) were employed. GasFinders are simple to use, flexible in their application, and relatively cost-effective measuring devices. However, several challenges were faced and overcome throughout the thesis. The precision of the employed GasFinder model was about 10 times lower than the manufacturer stated, which necessitated adaptation in the measurement setup. Additionally, an intercomparison before or after each measurement campaign was necessary to correct the offset and span between the employed GasFinders. In the first two studies presented in this thesis, experiments were conducted to evaluate the IDM. In a third study, experiments were conducted to assess the handling of complex source configurations with the IDM. The emissions determined in the third study were used as a basis for emission factors of Swiss biogas plants (BGPs) and wastewater treatment plants (WWTPs). In the first study, a known and predefined amount of CH 4 was released by an artificial source in a barn that mimics a dairy housing. For concentration measurements, GasFinders with a path length ii Thesis summary of 110 m were placed in downwind direction of the barn at a distance of 50 m, 100 m, 150 m, and 200 m. At the first three distances, an ultrasonic anemometer was placed in the middle of the GasFinder path length for executing turbulence measurements. Upwind of the barn, an additional GasFinder and an ultrasonic anemometer were installed. The main objective was to test the ideal measurement fetch for the IDM. The results of this experiment are included in the method section, where the conditions and the setup of an IDM measurement campaign are outlined. A release rate of 140 norm litres min -1 was chosen to achieve sufficient concentration enhancement at the GasFinder locations. The mean recovery rates of the experiment were between 0.55 – 0.76. In the second study, CH4 emission measurements from a naturally ventilated dairy housing were conducted in two measurement campaigns. During part of the campaign duration, emissions were also measured inside the housing with the inhouse tracer ratio method (iTRM). This allowed comparing the IDM with the iTRM, which was considered as a reference method for naturally ventilated livestock housings. For simultaneous emission intervals, the average IDM emissions were lower by 1 % and 8 % compared to the iTRM measurements, which was within the uncertainty of either of the two methods. Additionally, an uncertainty analysis for the IDM showed that measurement campaigns of at least 10 consecutive days are necessary to acquire reliable emission data. The third study addressed the handling of complex source configurations with the IDM. Emissions from four agricultural BGPs and two WWTPs in Switzerland were measured. The average BGP CH 4 emission varied between 0.39 kg h -1 and 2.22 kg h-1, which was less than 5 % of the plant’s CH4 production. The average CH4 emissions for the two WWTPs were 166 g population-equivalent-1 y -1 and 381 g population-equivalent-1 y -1, respectively. The BGPs often had livestock housings nearby that needed to be discriminated from the plant emission. It was demonstrated how the plant emission can be corrected for the nearby CH4 sources, which confounded the GasFinder measurements. Further, it was demonstrated how to combine multiple GasFinder measurements to a single line concentration for the bLS modelling. WWTPs are complex sources as they consist of multiple sub-sources with different emission strengths spread over a large area. Three different calculation approaches with different degree of details are presented for the combination of the individual sources in the bLS modelling: (i) A polygon over the entire WWTP area as a single source. (ii) All potential sources within the WWTP have a uniform emission density. (iii) Based on literature data, relative weighting of the individual sources is carried out. The maximum difference in emission between the most complex approach (iii) and the simplest approach (i) was 42 %. It could be shown that for large source areas (> 10,000 m2), approach (iii) is the preferred option, whereas for the measured BGPs the simple polygon approach (i) was sufficient. The recovery rate of the IDM from the release experiment (study 1) was below 1 and somewhat lower than previous studies with a similar experimental setting have shown. I was not able to conclusively identify the reasons for this result, which contrasts with the outcome of study 2 at the naturally ventilated dairy housing with a high consistency between the IDM and the iTRM used as a reference. Therefore, I suggest repeating the release experiment with an adapted setting and additionally roughly mapping the emission plume by a drone or a high-precision handheld sensor to monitor the dispersion of the plume. The field measurements at the WWTPs and the BGPs based on iii the chosen approach of source combination yielded data that are in the expected range according to current state of knowledge. The presented PhD thesis supports the aptitude of the IDM to measure emissions from complex sources like farms, BGPs, or WWTPs. Such measurements contribute to increasing the accuracy of national GHG inventories. Nevertheless, I suggest further investigations to better assess the accuracy of the IDM under complex conditions

Weltmarkt, internationale Arbeitsteilung und nationale Reproduktion: Neuere französische Internationalisierungstheorien -

Die politische Ökonomie in Frankreich hat in den letzten Jahren die Internationalisierung der kapitalistischen Produktionsverhältnisse als den Schwerpunkt ihrer theoretischen Bemühungen betrachtet. Dies hat zwei Ursachen, die auch die unterschiedliche Richtung im Vergleich zur linken Diskussion in der BRD erklären können. Zum ersten hat die »traditionelle« Linke bis vor dem Scheitern der Linksunion versucht, Konzepte einer neuen, solidarischen Politik gegenüber den Ländern der Dritten Welt zu entwickeln (vgl. Beaud u.a. 1979). Dazu waren umfangreiche Arbeiten über das frühere französische Kolonialsystem und dessen neokolonialistische Fortsetzung notwendig (vgl. u.a. CEDETIM 1978). Die französische Bourgeoisie übt gerade in den früheren Kolonien eine aggressive Brückenkopffunktion für den Imperialismus aus. Die militärischen Interventionen in Zaire, Niger, Zentralafrikanische Republik sind Ausdruck dieser Politik. Diese politischen Zusammenhänge haben die Linke gleichsam gezwungen, sich verstärkt mit Neokolonialismus und abhängiger Entwicklung in der Dritten Welt auseinanderzusetzen. In der Theoriegeschichte entscheidend war dabei die Kritik und Überwindung der Theorie »des ungleichen Tauschs« (Amin/Emmanuel), die zu neuen Konzepten führte. Die wichtigsten Arbeiten sind nicht im offiziellen Rahmen der linken Parteien entstanden

Quantification of methane emissions from waste water treatment plants

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

Ammonia emissions from a dairy housing and wastewater treatment plant quantified with an inverse dispersion method accounting for deposition loss

Ammonia (NH3) emissions negatively impact air, soil, and water quality, hence human health and biodiversity. Significant emissions, including the largest sources, originate from single or multiple structures, such as livestock facilities and wastewater treatment plants (WWTPs). The inverse dispersion method (IDM) is effective in measuring total emissions from such sources, although depositional loss between the source and point of measurement is often not accounted for. We applied IDM with a deposition correction to determine total emissions from a representative dairy housing and WWTP during several months in autumn and winter in Switzerland. Total emissions were 1.19?±?0.48 and 2.27?±?1.53?kg NH3 d?1 for the dairy housing and WWTP, respectively, which compared well with literature values, despite the paucity of WWTP data. A concurrent comparison with an inhouse tracer ratio method at the dairy housing indicated an offset of the IDM emissions by?<?20%. Diurnal emission patterns were evident at both sites mostly driven by changes in air temperature with potential lag effects such as following sludge agitation. Modeled deposition corrections to adjust the concentration loss detected at the measurement point with the associated footprint were 22?28% of the total emissions and the cumulative fraction of deposition to emission modeled with distance from the source was between 7% and 12% for the measurement distances (60?150?m). Although estimates of depositional loss were plausible, the approach is still connected with substantial uncertainty, which calls for future validation measurements. Longer measurement periods encompassing more management activities and environmental conditions are required to assess predictor variable importance on emission dynamics. Combined, IDM with deposition correction will allow the determination of emission factors at reduced efforts and costs, thereby supporting the development and assessment of emission reducing methods and expand the data availability for emission inventories. Implications: Ammonia emissions must be measured to determine emission factors and reporting national inventories. Measurements from structures like farms and industrial plants are complex due to the many different emitting surfaces and the building configuration leading to a poor data availability. Micrometeorological methods provide high resolution emission data from the entire structure, but suffer from uncertainties, as the instruments must be placed at a distance from the structure resulting in a greater loss of the emitted ammonia via dry deposition before it reaches the measurement. This study constrains such emission measurements from a dairy housing and wastewater treatment plant by applying a simple correction to account for the deposition loss and compares the results to other methods

Using the inverse dispersion method to determine methane emissions from biogas plants and wastewater treatment plants with complex source configurations

Wastewater treatment plants (WWTPs) and biogas plants (BGPs) are significant sources of methane (CH4), with a combined share of around 40 % within the waste sector of the Swiss national emission inventory. We conducted whole-plant CH4 emission measurements at two WWTPs and four agricultural BGPs in Switzerland using the inverse dispersion method (IDM). This involved open-path concentration measurements up- and downwind of the plant in combination with a backward Lagrangian stochastic (bLS) model. WWTPs in particular consist of multiple CH4 sources with different areas and emission strengths. For the combination of the individual emission sources in the bLS modelling, three different calculation approaches with different levels of detail were applied: (i) single source over enveloping polygon area, (ii) uniform emission density for all individual source areas, (iii) specified relative weighting of individual sources based on literature data. Average CH4 emissions for WWTP 1 and WWTP 2 were 0.82 kg h-1 and 0.61 kg h-1 and scaled to population equivalents (PE) 166 g PE-1 y-1 and 381 g PE-1 y-1, respectively. BGPs CH4 emissions varied between 0.39 kg h-1 and 2.22 kg h-1, corresponding to less than 5 % of the plants’ CH4 production. The highest numbers were due to measurements during other than normal operating conditions. The emissions of WWTPs and BGPs comply with literature values. Approach (iii) with source weighting led to a difference of up to 43 % for the two WWTPs compared to the assumption of uniform emissions. Furthermore, we demonstrate how multiple open-path concentration measurements can be combined and how the measurements can be corrected for nearby external CH4 sources not belonging to the investigated plants. The results of the present study contribute to improved emission data from the waste sector

Towards the data-driven circular and embedded supply chain : considerations from an ICT perspective

In the academic literature on Supply Chain Management the vision of a paradigm change from linear pipelines toward circular, postfossil, servitized and degrowth supply chains is drawn. Modern information and communication technologies are a key enabler for the realization of this vision. However, the literature remains vague on how these technologies can support the transformation. This publication aims to contribute to closing this gap. It provides an overview of relevant trends, technologies, and concepts, presents a visionary scenario for a data-driven and platformbased circular SCM, and identifies essential steps for its realization. Methodologically, the study is based on a literature review and a single case study in combination with an action research approach

Ammonia and greenhouse gas emissions from slurry storage : A review

Storage of slurry is an important emission source for ammonia (NH3), nitrous oxide (N2O), methane (CH4), carbon dioxide (CO2) and hydrogen sulfide (H2S) from livestock production. Therefore, this study collected published emission data from stored cattle and pig slurry to determine baseline emission values and emission changes due to slurry treatment and coverage of stores. Emission data were collected from 120 papers yielding 711 records of measurements conducted at farm-, pilot- and laboratory-scale. The emission data reported in a multitude of units were standardized and compiled in a database. Descriptive statistics of the data from untreated slurry stored uncovered revealed a large variability in emissions for all gases. To determine baseline emissions, average values based on a weighting of the emission data according to the season and the duration of the emission measurements were constructed using the data from farm-scale and pilot-scale studies. Baseline emissions for cattle and pig slurry stored uncovered were calculated. When possible, it was further distinguished between storage in tanks without slurry treatment and storage in lagoons which implies solid-liquid separation and biological treatment. The baseline emissions on an area or volume basis are: for NH3: 0.12 g m−2 h-1 and 0.15 g m−2 h-1 for cattle and pig slurry stored in lagoons, and 0.08 g m−2 h-1 and 0.24 g m−2 h-1 for cattle and pig slurry stored in tanks; for N2O: 0.0003 g m−2 h-1 for cattle slurry stored in lagoons, and 0.002 g m−2 h-1 for both slurry types stored in tanks; for CH4: 0.95 g m-3 h-1 and 3.5 g m-3 h-1 for cattle and pig slurry stored in lagoons, and 0.58 g m-3 h-1 and 0.68 g m-3 h-1 for cattle and pig slurry stored in tanks; for CO2: 6.6 g m−2 h-1 and 0.3 g m−2 h-1 for cattle and pig slurry stored in lagoons, and 8.0 g m−2 h-1 for both slurry types stored in tanks; for H2S: 0.04 g m−2 h-1 and 0.01 g m−2 h-1 for cattle and pig slurry stored in lagoons. Related to total ammoniacal nitrogen (TAN), baseline emissions for tanks are 16% and 15% of TAN for cattle and pig slurry, respectively. Emissions of N2O and CH4 relative to nitrogen (N) and volatile solids (VS) are 0.13% of N and 0.10% of N and 2.9% of VS and 4.7% of VS for cattle and pig slurry, respectively. Total greenhouse gas emissions from slurry stores are dominated by CH4. The records on slurry treatment using acidification show a reduction of NH3 and CH4 emissions during storage while an increase occurs for N2O and a minor change for CO2 as compared to untreated slurry. Solid-liquid separation causes higher losses for NH3 and a reduction in CH4, N2O and CO2 emissions. Anaerobically digested slurry shows higher emissions during storage for NH3 while losses tend to be lower for CH4 and little changes occur for N2O and CO2 compared to untreated slurry. All cover types are found to be efficient for emission mitigation of NH3 from stores. The N2O emissions increase in many cases due to coverage. Lower CH4 emissions occur for impermeable covers as compared to uncovered slurry storage while for permeable covers the effect is unclear or emissions tend to increase. Limited and inconsistent data regarding emission changes with covering stores are available for CO2 and H2S. The compiled data provide a basis for improving emission inventories and highlight the need for further research to reduce uncertainty and fill data gaps regarding emissions from slurry storage

I M Avatar: Implicit Morphable Head Avatars from Videos

Traditional morphable face models provide fine-grained control over expression but cannot easily capture geometric and appearance details. Neural volumetric representations approach photo-realism but are hard to animate and do not generalize well to unseen expressions. To tackle this problem, we propose IMavatar (Implicit Morphable avatar), a novel method for learning implicit head avatars from monocular videos. Inspired by the fine-grained control mechanisms afforded by conventional 3DMMs, we represent the expression- and pose-related deformations via learned blendshapes and skinning fields. These attributes are pose-independent and can be used to morph the canonical geometry and texture fields given novel expression and pose parameters. We employ ray tracing and iterative root-finding to locate the canonical surface intersection for each pixel. A key contribution is our novel analytical gradient formulation that enables end-to-end training of IMavatars from videos. We show quantitatively and qualitatively that our method improves geometry and covers a more complete expression space compared to state-of-the-art methods