title: Multisource emission retrieval within a biogas plant based on inverse dispersion calculations--a real-life example.
abstract: Open digestate storage tanks were identified as one of the main methane (CH4) emitters of a biogas plant. The main purpose of this paper is to determine these emission rates using an inverse dispersion technique in conjunction with open-path tunable diode laser spectroscopy (OP-TDLS) concentration measurements for multisource reconstruction. Since the condition number, a measure of "ill-conditioned" matrices, strongly influences the accuracy of source reconstruction, it is used as a diagnostic of error sensitivity. The investigations demonstrate that the condition number for a given source-sensor configuration in the highly disturbed flow field within the plant significantly depends on the meteorological conditions (e.g., wind speed, stratification, wind direction, etc.). The CH₄ emissions are retrieved by removing unrepresentative periods with high condition numbers, which indicate uncertainty in recovering the individual sources. In a final step, the CH₄ emissions are compared with the maximum biological methane potential (BMP) in the digestate analyzed under laboratory conditions. The retrieved methane emission rates represent an average of 50% of the maximum BMP of the stored digestate in the winter months, while they comprised an average of 85% during the measurement campaigns in the summer months. The results indicate that the open tanks have the potential to represent a substantial emission source even during colder periods.
authors.affiliation: Department of Water-Atmosphere-Environment, Institute of Waste Management, University of Natural Resources and Life Sciences, Muthgasse 107, 1190, Vienna, Austria, marlies.hrad@boku.ac.at.
authors.forename: Marlies
authors.initials: M
authors.lastname: Hrad
authors.forename: Martin
authors.initials: M
authors.lastname: Piringer
authors.forename: Ludek
authors.initials: L
authors.lastname: Kamarad
authors.forename: Kathrin
authors.initials: K
authors.lastname: Baumann-Stanzer
authors.forename: Marion
authors.initials: M
authors.lastname: Huber-Humer
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control / Q000706:statistics & numerical data*; D056804:Biofuels; D004784:Environmental Monitoring / Q000379:methods; D008697:Methane / Q000032:analysis*; D008956:Models, Chemical; D014919:Wind
chemical_list: D000393:Air Pollutants; D056804:Biofuels; D008697:Methane