10 promising mobile technologies for finding natural gas leaks swiftly and cheaply have competed in the Mobile Monitoring Challenge, the first independent assessment of moving gas leak detectors at well sites.
The organisers of the contest – Stanford University’s Natural Gas Initiative and the US Environmental Defense Fund – describe the outcomes in a study published in Elementa this month by University of California Press.
While billed as a ‘challenge’, the organisers had no intention of declaring a winner, as the technologies (located on trucks, drones and aeroplanes) focused on different aspects of leak detection, such as exact location or size of the leak. While the technologies are still in development, overall, they all found gas leaks quite well.
Leaks in the production, processing and transport of natural gas emit methane – the main constituent of natural gas – into the atmosphere.
In 2016, the U.S. Environmental Protection Agency moved to reduce methane emissions across the natural gas industry, which spurred the development of faster, less expensive detection technologies. Late last month, however, the U.S. EPA moved to roll back these methane regulations.
Adam Brandt is an Associate Professor of Energy Resources Engineering and senior author of the study. He detailed that the technologies are generally effective at detecting leaks and can act as a first line of defence.
“Gas system operators will often want to confirm leaks with conventional optical gas imaging systems, but these mobile technologies usually tell you where to look for leaks very quickly.”
A crew of two people using a conventional imaging system can visit four to six well pads a day. All the mobile technologies are considerably faster than that, though their speeds vary considerably. Plane-based systems work more quickly than trucks, which are faster than drones. Because worker time is a large part of detection cost, speeding up detection allows oil and gas companies to find more leaks while spending less money.
The results
Last year, as part of the Mobile Monitoring Challenge, nine corporations and a university research team showcased their technologies at controlled testing facilities in Fort Collins, Colorado, and near Sacramento, California.
All technologies were effective at detecting leaks. Eight of nine detected leaks correctly 75 per cent of the time (one technology did not have enough flights to be included in the study’s summary). Five of nine systems detected 90 per cent or more of the leaks, including tiny emissions of one cubic foot of gas per hour. While this is extremely positive, most of the systems tested need to improve their ability to quantify the size of the leaks. Also, the technologies varied in their ability to detect the precise location of the leaks, though this is often by design.
For example, one start-up’s drone-based system detected 100 per cent of leaks and had no false positives. Further, it accurately identified the leaking piece of equipment – rather than just the well pad – 84 per cent of the time. However, when quantifying the size of leaks, the system’s estimates were relatively close just 36 per cent of the time. For the other eight systems, by the same relatively strict measure, quantification accuracy ranged from 18 to 53 per cent.
“This is only the first step to demonstrating that these technologies could help reduce emissions on a level equivalent to existing approaches,” Mr Brandt said.
“The tests were run in the spring of 2018, and I’m sure most—if not all—of these technologies have been improved since then.”
Further advances could be in jeopardy, however. According to lead author of the study and Assistant Professor at the Harrisburg University of Science & Technology, Arvind Ravikumar, the recent U.S. EPA announcement about rolling back methane regulations is not just bad for the environment, but also deprives oil and gas communities of high-paying, local jobs that these innovative technology companies could create.
“Rolling back the regulations could stifle the development of these technologies,” he said.
The researchers said that an assessment like this can help regulators better understand these systems and provide a possible path to large-scale adoption for compliance purposes.
Designs for different uses
The Mobile Monitoring Challenge was not a head-to-head competition as the technologies tested are designed to accomplish different things.
“No single technology can meet all the requirements for leak detection and quantification across the natural gas supply chain,” Mr Ravikumar said.
“The key to large-scale deployment is to match the strength of each technology, like speed, accuracy and cost, with the right leak detection application. What works for a complex processing facility might not work for long-distance transmission pipelines.”
Assistant Professor of Energy Engineering, Harrisburg University of Science and Technology, Arvind Ravikumar. Image sourced via arvindravikumar.com
The systems of some participants focus on identifying leaks from a cluster of equipment, which could include a wellhead, a separator and a tank, for example. In such cases, operators would use optical gas imaging systems or similar technology to identify the specific source of the leak before initiating repairs.
Similarly, two of the technologies tested are designed to quickly identify large leaks, rather than all leaks.
More than half the methane lost in natural gas production and processing comes from just 5 per cent of leaks. Finding and fixing these ‘super-emitters’ is critical to reducing methane emissions. Even without strict regulations, natural gas companies could reduce emissions voluntarily.
Inexpensive detectors combined with focused use of optical gas imaging systems could pay for themselves by reducing losses of company product.
