Geoscience Australia led study to improve greenhouse gas emissions quantification techniques
Geoscience Australia recently led a large collaborative effort with 16 different research teams from Australia and Germany, working to improve the accuracy of local-scale greenhouse gas emissions quantification techniques.
The study demonstrated that using a combination of techniques provides a more accurate estimate of possible greenhouse gas emissions rather than relying on a single technique.
By using a combined approach more accurate estimates can be generated for input into Australia's National Greenhouse Accounts.
The study is described as one of the most comprehensive assessments of atmospheric techniques used to estimate emission rates ever undertaken. Participants in the trial along with Geoscience Australia included University of Wollongong, University of Melbourne, Macquarie University, CSIRO Energy, CSIRO Oceans and Atmosphere, Western Sydney University, CSIRO Data 61, University of Adelaide, CSIRO Mineral Resources, University of Western Australia, National Geosequestration Laboratory, Bruker Optik, FLIR, Department of Industry, Innovation and Science and CO2CRC.
Being able to measure fugitive greenhouse gas emissions is important for supporting national and global greenhouse gas reduction targets. It is essential to have confidence in the techniques used to estimate methane emissions from the energy and agricultural sectors, natural greenhouse gas seepage, or potential carbon dioxide leakage from geological storage projects (CO2 can be injected into into underground geological formations, such as Oil fields, gas fields, saline formations, unmineable coal seams to prevent it from escaping to the surface).
However, monitoring the effectiveness of geological storage of CO2 is challenging because CO2 is present naturally in the atmosphere, soil, ocean and groundwater.
A methane and carbon dioxide release experiment was undertaken at the Ginninderra Controlled Release Facility in Canberra, Australia from April to June 2015. Eight different quantification techniques were simultaneously compared to determine the effectiveness of both stationary and mobile methods, and included a blind study where the actual release rate was unknown.
Project leader, Dr Andrew Feitz explained that each of the research teams used different measurement techniques and models to produce an estimate of the actual release rate without knowing the true value. The individual estimates varied greatly, but by bringing all of the results together the researchers were able to produce a much closer estimate of the release rate.
"In the methane release experiment, not one of uncertainty ranges for the estimates from eight different techniques contained the actual release rate," Dr Feitz said.
"By applying a combined approach, like those used in weather forecasting and climate models, we were able to greatly improve the accuracy of the estimate and provide an uncertainty range that contained the actual release rate," he added
Many novel and promising techniques were deployed for estimating the emission rate and also for gas detection and mapping applications. These techniques are not yet as sensitive as high precision gas analysers, but the performance of miniaturised sensors is improving rapidly. This technology offers considerable potential for mobile applications, including automating gas monitoring and leak detection using ground robots or unmanned aerial vehicles.
The study successfully demonstrated that is it possible to use airborne detection of a small CO2 leak using a small helicopter UAV (unmanned aerial vehicle or drone).
By using drones, the number of expensive high accuracy sensors necessary can be reduced to one piece per drone. The spatial coverage is limited only by the robot’s on-board power. A sparse temporal resolution can be addressed by repeatedly sending the same drone into the field or by alternating drones with identical configuration. It also allows the operator to stay in a safe distance. With autonomous operation the operator can concentrate on the results received from the robot while not being present at the emission site at all. Current work is focusing on automating the aerial platform to enable autonomous flight for coverage over larger areas, the tracking of gas plumes as well as the creation of CO2 distribution maps for different altitudes.