Natural gas is considered a bridging technology in the energy transition because it produces fewer carbon emissions than coal, for example. However, when leaks exist, methane is released into the atmosphere, leading to a dramatic increase in the carbon footprint of natural gas, as methane is a much stronger greenhouse gas than carbon dioxide. Therefore, we conducted a detailed study of methane emissions from gas-powered end-use appliances and then compared their climate impacts with those of electricity-powered appliances. We used the Munich Oktoberfest as a case study and then extended the study to 25 major natural gas consuming countries. This showed that electricity has been the more climate-friendly energy source at Oktoberfest since 2005, due to the extensive use of renewable electricity at the festival and the presence of methane emissions, particularly caused by incomplete combustion of natural gas appliances. Further, our global study shows that using electric appliances for cooking and heating would be more climate-friendly not only at Oktoberfest but also in several countries around the world, depending on the energy mix used and the leakage rate of natural gas. With this study, we demonstrate one way in which countries with a high renewable share in power generation, in particular, can reduce a significant amount of carbon emissions in the future.

<p>Up to now, festivals have not been considered a significant methane (CH<sub>4</sub>) emission source and events with a limited duration were not included in the emission inventories. We have intensively investigated the Munich Oktoberfest, the world’s largest folk festival, for two consecutive years. Oktoberfest is a potential source for CH<sub>4</sub> as a high amount of natural gas (about 200,000 m³) for cooking and heating is used.</p><p>The results from our 2018 investigation show that CH<sub>4</sub> emissions at Oktoberfest not only come from human biogenic emissions. It is more likely that fossil-fuel related emissions are the major contributors to the Oktoberfest emissions (Chen et al. 2019). In 2019, our goal was to look closer into the source attribution. We used both a portable gas measurement system (LI-COR LI‑7810 Trace Gas Analyzer) in a backpack to measure the CH<sub>4</sub> concentrations, and air sampling bags to examine the ethane/methane ratio and isotopic composition of the exhaust gas (δ13C, δD).</p><p>We walked around the perimeter of Oktoberfest to measure the CH<sub>4</sub> concentration upwind and downwind of the Oktoberfest premises for several hours each day during the two-week festival. In addition, we entered the festival with our instrument to investigate the emission hotspots, i.e. tents and booths, thoroughly. The measurements were carried out both during and after the time of the festival to compare the differences in emission strength and distribution.</p><p>The backpack measurements around the Oktoberfest perimeter show enhancements up to several hundred ppb compared to background values and measurements performed after the festival. The concentration enhancements on the premises were even higher: up to 3,000 ppb for hotspot regions. The ethane/methane ratios and isotopic measurements show clear indications that the emission sources are thermogenic.</p><p>Furthermore, a CFD (Computational Fluid Dynamics) simulation was developed to simulate the gas dispersion within and around the terrain. The simulation uses Reynolds-Averaged Navier-Stokes equations and the k-ε turbulence model for the fluid flow. Wind speed and direction measurements taken close to the festival area were used as the boundary conditions. The dispersion of methane is solved afterwards using the unsteady convection-diffusion equation.</p><p>We will present the strengths and spatial/temporal distributions of the Oktoberfest emissions, assessed using the backpack measurements combined with a CFD model. Further, a comparison between the results of two consecutive years will be given. </p><p> </p><p>Chen, J., Dietrich, F., Maazallahi, H., Forstmaier, A., Winkler, D., Hofmann, M. E. G., Denier van der Gon, H., and Röckmann, T.: Methane Emissions from the Munich Oktoberfest, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-709, in review, 2019</p>

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To reach the goal of net-zero greenhouse gas (GHG) emissions, the usage of natural gas is considered to be a bridge technology in many countries, as it is promoted to be more climate-friendly than burning coal (Ladage et al., 2021). However, methane (CH 4 ), the main component of natural gas, has a much stronger warming potential (GWP 20 of 86 with the consideration of climate-carbon feedback) than carbon dioxide (CO 2 ) and is released when natural gas enters the atmosphere incompletely burned (Myhre et al., 2013). Recent studies have shown that anthropogenic fossil CH 4 emissions are generally underestimated (Alvarez et al., 2018;Hmiel et al., 2020;Schwietzke et al., 2016) and that the targets set in the Paris Agreement can only be met if CH 4 emissions are drastically reduced (Nisbet et al., 2019).To improve the quantification of CH 4 emissions, many studies around the world have focused on determining these CH 4 emissions using various measurement and modeling approaches including mobile street-level

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