Linear sensor for areal subsurface gas monitoring - Calibration routine and validation experiments

Setup of a large-scale test field for distributed soil gas sensors and testing of a monitoring method based on tomography

“…The flushing gas supply was controlled by a mass flow controller as of the beginning of 2015, i.e., in 2014 we regulated this flow by a hand valve, and the mixing of CO 2 with the compressed air that was needed for the inverse calibration routine [3] was performed in a small chamber that had a vent for pressure equalization, so it is likely that environmental parameters influenced the results of the inverse calibration. Comparing the raw measurements of the trials with each other confirms this finding.…”

“…The subsequent CO 2 -formation within the subsurface was observed for about one day. To obtain calibrated sensor readings from the membrane-based gas sensors, the inverse calibration method presented in [3] was previously applied to the sensors. The time span for a measurement of the concentration-dependent pressure evolution within a linear sensor was uniformly adjusted to 10 s with the restriction that only one sensor at a time is measuring -the remaining sensors are conditioned by the reference gas.…”

“…However, adequate technologies for comprehensive monitoring of subsurface carbon dioxide (CO 2 ) storage areas¹ are still missing. Essential aspects associated with these technologies are the rapid identification of CO 2 leaks in critical areas and the continuous quantification of escaping CO 2 from the repository [3]. In addition, transport and storage facilities for hydrogen (H 2 ) and natural gas (containing mainly methane -CH 4 ) demand for equivalent rapid monitoring solutions, e.g., to enhance the safety of energy supplies of renewable energy systems (photovoltaic, wind power) by power-to-gas conversion technologies.…”