39400 2017 eng lecture 0 -- -- -- Geogenic gases such as CH4 or CO2 from natural sources, gases (CCS-CO2, H2, Natural gas, City gas …) from a geological repository, or a leaking gas pipeline can present serious risks in industrial and urban areas where the density of infrastructural elements increases as well as above and below ground. To extend the lead time for risk treatment in such critical regions, reliable detection of gases within the shallow subsurface is required to observe critical gas accumulations before degassing into the atmosphere. A near real-time monitoring approach is introduced to determine the volumetric expansion of such a gas escaping from a leak in the subsurface. Considering the pressure relaxation with the ambient air pressure, the approach enables the forecasting of the final size of a pressurized gas body in terms of characteristic lengths. According to theoretical basics, such a characteristic length, which allows to perform a gas (safety) measurement based on a purely geometrical measure, behaves independently of subsurface properties, i.e., it enables a reliable quantification of the escaping gas, irrespective of its heterogeneous flow path distribution. A field test for a 10 l/min pinhole leakage of CO2 injected in an unsaturated Chernozemic soil (agricultural test field Bad Lauchstädt)that was equipped with linear gas sensors demonstrates the lateral-vertical volumetric gas expansion along the environment of these gas sensors, and confirms the applicability of the new characteristic length approach. UFZ EnergyDays 2017 Leipzig, Germany 15.03.2017 16.03.2017 0 D. Lazik Patrick P. Neumann Matthias Bartholmai eng uncontrolled CO2 eng uncontrolled Carbon capture and storage eng uncontrolled Leakage eng uncontrolled Monitoring Analytische Chemie Angewandte Physik Sanitär- und Kommunaltechnik; Umwelttechnik Datei im Netzwerk der BAM verfügbar ("Closed Access") Präsentation