A team of Princeton ECE researchers has developed a method to pinpoint gas drilling and sewer systems leak, both big and small, for speedy repair. Their laser-based sensing approach can accurately detect and quantify both large greenhouse gas leaks and leaks up to 25 times smaller than those typically detected at natural gas facilities using other methods, localizing the emissions source to within a meter.
The new technology takes advantage of the remote-sensing capabilities of lasers combined with the agility of drones. This means it can also be used to quickly spot otherwise unseen leaks in hard-to-access areas.
The new approach consists of a small drone outfitted with only a retroreflector, a type of mirror that reflects incoming light directly back to the source, and a base station of gas sensing equipment with the capability to track the drone’s movement during flight. Bouncing a laser beam off the drone as it flies to set points around a suspected leak allows an operator to pinpoint the source of the leak and measure its intensity.
Drone-based techniques for atmospheric sensing already exist, but they usually require mounting a gas sensor directly onto a drone. “You really can’t fit more than one gas sensor on a drone at a time; otherwise, it just becomes too big and bulky to fly. And you probably don’t want to risk flying an expensive sensor over the lagoon of a wastewater treatment plant or the flaring of a compressor station,” said Mark Zondlo, the study co-author.
Instead of overburdening the drone with sensors, the Princeton group offloaded the expensive gas-sensing components to the base station. The base station can fit on a mobile platform such as a van, meaning that the drone only needs to carry a small mirror. That change allowed the researchers to use smaller, less expensive drones with longer flight times to collect highly detailed emissions data across large areas, potentially unlocking the ability to monitor entire natural gas transmission and distribution facilities in a single drone flight.
“Our approach allows us to bypass the major constraints of using drones and enables us to make full use of their potential,” Zondlo said. “It’s really a paradigm shift in how we can use drones for atmospheric sensing.”
The team’s approach could also enable simultaneous measurements of multiple gases, a feat that is exceedingly difficult with other drone-based approaches due to size, weight, and power considerations.
Adding the ability to measure other gases like carbon dioxide and ammonia alongside methane would be as simple as adding other lasers of different wavelengths to the base system. “All you’d need to do is add a second laser to the system,” explained Michael Soskind, the first author of the study. “The rest of the system is already built out to do the work.”
Because it offers users a great amount of flexibility, the team sees its approach as a technology platform that could spur future innovation and applications beyond methane leak detection.
“The most exciting thing is not simply the methane sensing abilities of the technology we developed,” said Gerard Wysocki, associate professor of electrical and computer engineering and associated faculty at the Andlinger Center for Energy and the Environment. “It’s really about unlocking the capability for researchers and practitioners to use drones and other remote sensing techniques to take detailed measurements of small leaks and reconstruct emissions plumes. It’s a technology that opens the doors for efficient leak detection and repair, which can help producers mitigate the safety and environmental hazards of those leaks while also saving them time and money.”
- Michael G. Soskind, Nathan P. Li, Daniel P. Moore, Yifeng Chen, Lars P. Wendt, James McSpiritt, Mark A. Zondlo, Gerard Wysocki. Stationary and drone-assisted methane plume localization with dispersion spectroscopy. Remote Sensing of Environment, 2023; DOI: 10.1016/j.rse.2023.113513