Researchers locate greenhouse gas leaks with the aid of drones and lasers.

A group of Princeton researchers has developed a method for quickly repairing small and large leaks as evidence mounts that gas drilling and sewer systems leak far more greenhouse gases than previously thought.

Their laser-based sensing method, which is described in detail in a paper that was published in Remote Sensing of the Environment, is able to pinpoint the emissions source to within a meter and accurately quantify both large leaks of greenhouse gases and leaks that are up to 25 times smaller than those that are typically detected at natural gas facilities using other methods.

The new technology can also be used to quickly spot otherwise unseen leaks in hard-to-access areas because it takes advantage of the remote-sensing capabilities of lasers and the agility of drones. The researchers say this innovation unlocks game-changing potential for atmospheric sensing.

“You can’t fit more than one gas sensor on a drone at a time; otherwise, it becomes too large and bulky to fly. And you probably don’t want to take the chance of flying an expensive sensor over a wastewater treatment plant’s lagoon or a compressor station’s flare.”

Mark Zondlo, study co-author, professor of civil and environmental engineering.

According to Gerard Wysocki, associate professor of electrical and computer engineering and associated faculty at the Andlinger Center for Energy and the Environment, “current approaches for detecting leaks frequently rely on handheld infrared cameras that are labor-intensive to operate and insensitive to small leaks, or they use methods that require setting up extensive measurement infrastructure ahead of time.” However, setting up your sensing area with a drone is completely up to you.

Researchers use a small drone with only a retroreflector, a type of mirror that reflects light directly back to the source, and a base station with gas sensing equipment that can track the drone’s movement during flight. An operator can determine the leak’s source and measure its intensity by bouncing a laser beam off the drone as it flies around a suspected leak.

Mark Zondlo, a co-author of the study and associate professor of civil and environmental engineering at the Andlinger Center for Energy and the Environment, stated, “That’s really the holy grail of leak detection.”

There are drone-based techniques for atmospheric sensing, but most of them require mounting a gas sensor directly onto the drone. Zondlo said this practice quickly runs into major roadblocks related to the maximum weight a drone can carry and the risk of flying a drone loaded with expensive sensors in dangerous environments.

During field experiments, co-author Lars Wendt controls the drone. Credit: “You really can’t fit more than one gas sensor on a drone at a time, or it just becomes too big and bulky to fly,” says Princeton University. Additionally, flying a costly sensor over a wastewater treatment plant’s lagoon or a compressor station’s flaring is probably not something you want to risk,” Zondlo stated.

The Princeton group decided to offload the pricey gas sensing components to the base station rather than overloading the drone with sensors. The base station can fit on a mobile platform like a van, so the drone only needed to carry a small mirror. Because of this change, the researchers were able to collect highly detailed emissions data across large areas using smaller, less expensive drones with longer flight times. This could have made it possible to monitor entire natural gas transmission and distribution facilities with a single drone flight.

Zondlo stated, “Our approach enables us to make full use of their potential and bypass the major constraints of using drones.” In terms of how we can use drones for atmospheric sensing, this is truly a paradigm shift.”

The sensing method might also be able to take measurements of multiple gases at the same time, which is impossible with other drone-based methods because of their size, weight, and power.

Michael Soskind, the primary creator of the review and an alumni understudy in electrical and PC designing, said adding the capacity to gauge different gases like carbon dioxide and smell salts close by methane would be pretty much as straightforward as adding different lasers of various frequencies to the base framework. “Adding a secondary laser to the system would be all that was required, he explained. The remainder of the system has already been designed to perform the task.

Wysocki said that he sees the team’s approach as a technology platform that could encourage innovation and applications beyond methane leak detection because it gives users a lot of flexibility.

“The most interesting thing isn’t just the methane-detecting capacities of the innovation we created,” he said. “It’s truly about opening the capacity for specialists and professionals to utilize drones and other remote detecting strategies to take nitty-gritty estimations of little holes and remake outflows crests. It is a technology that makes it possible to quickly find and fix leaks. This can help manufacturers reduce the risks to their safety and the environment caused by leaks while also saving them money and time.”

More information: Michael G. Soskind et al, Stationary and drone-assisted methane plume localization with dispersion spectroscopy, Remote Sensing of Environment (2023). DOI: 10.1016/j.rse.2023.113513

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