The field of drone technology is ever expanding and is on the cutting edge of research. Derek Hollenbeck is a graduate student at University of California, Merced who has been involved in furthering drone research. He has published research papers regarding methane detection using unmanned aircraft systems (UAS) and has given some time to the engineering service-learning team to share about his field and research with us.
The development of using drones to detect methane gas is a complicated process. Methane is not a visible gas, so researchers must rely on modeling and theory to help the detection process. The gas can be detected through a thermal imaging system, such as midwave infrared (MWIR) optical gas imaging, and research teams are using tunable diode laser absorption spectroscopy (TLDAS) based tools, to detect the invisible gas and take data samples in the field. These tools are based on, and miniaturized from, tools that were from the TDLAS used on the NASA Mars Curiosity rover. Although these sensors are extremely sensitive making it possible for them to be used on an UAS effectively, they are still not yet sensitive enough to be used for small emissions. Detecting the gas is only a small part of the difficulty when it comes to the search. Accurately recording samples brings more challenge as researchers are now dealing with detecting the gas as it moves within a three-dimensional space. Atmospheric conditions, as well as wind can affect the movement of gas as it is emitted from the earth. This makes taking good readings and colleting good data more difficult for researchers. The first steps were to ensure that the drones were able to collect good data by modeling the movement of gas in the air to have the drones fly to points within the distribution of the gas to collect data samples. Some of the papers Mr. Hollenbeck wrote covered the effects and importance of wind measurements when collecting data as well as test flights for methane detection with fixed wing systems.
This research is being used to help further research in two major fields right now. In the oil and gas industry, drones are being considered to help increase the safety of the infrastructure systems in place currently. Drones could potentially be used to make rounds for routine inspections and detect gas leaks within these systems. This could ultimately be an automated process that occurs more frequently than current checks and would increase the safety of everyone involved from consumers to workers by detecting gas leaks faster, and possibly more accurately, than current methods. A second field the drone systems are being used is environmental research. In the arctic regions, research teams are studying permafrost and the methane gas being emitted. There are currently eddy covariance flux towers set up for this research, but these systems have some major drawbacks. The eddy covariance towers are large pieces of equipment that are not easily moveable as well as require electrical power to operate and personnel to maintain them. This makes eddy covariance towers impractical to use in areas without power or in hard to reach regions. Drones could potentially fill in this gap by being able to survey regions of land that the towers could not be set up to use and add to the data that is already currently being tracked. In addition, due to the highly sensitive sensors being used, drones could help survey other possible emission sources not currently being monitored such as urban ponds and vernal pools. All of this would give a better large-scale picture of what the true global emissions levels are and further refine modeling for the effects of global emissions we are currently using.
