A Q&A with Bridger Photonics Accounts Manager Chris Arrasmith
Bridger Photonics’ Gas Mapping LiDAR™ (GML) scans for all sectors of the natural gas supply chain, including distribution utilities, sometimes called local distribution companies, or LDCs, that deliver natural gas into our homes and businesses for use. Distribution utility companies not only benefit from leak detection and repair for safety reasons, but leak detection is also an important component of overall methane emissions reduction.
We sat down with Chris Arrasmith, Accounts Manager at Bridger Photonics, to discuss the distribution sector’s unique challenges and how GML technology helps distribution utilities.
Q: What are the biggest challenges your distribution clients face today?
Arrasmith: One key challenge for distribution clients is pinpointing leak locations and figuring out which crew to send to investigate. Oftentimes, different crews are responsible for different aspects of leak investigation and repair, depending on whether the source is on the distribution infrastructure (pre-meter), or customer side (post-meter). While piping under a sidewalk to a customer’s home may be very near to a gas line in someone’s backyard, the two situations require separate actions by different teams within the distribution utility. Being able to deploy the correct team on the first dispatch saves a great deal of time and cost.
A second challenge is in efficiently conducting leak surveys. Surveys by ground crews with handheld detectors take an immense amount of time and resources relative to aerial scans, since ground crews drive to a particular area, search for leaks on foot with hand-held instruments, and often must manage access issues (e.g. fenced backyards). Also, the handheld sensors used for ground surveys don’t quantify emission rates, so prioritizing repairs can be difficult.
Q: What role does technology have in overcoming these challenges?
Arrasmith: Sensitive aerial leak detection, like Gas Mapping LiDAR, is a strong complement to foot patrols. By flying over the infrastructure with a helicopter-mounted sensor, we can cover in a few hours what might take a ground crew several days to survey. The measurements from an aircraft also provide accurate localization so crews can differentiate between pre-meter and post-meter leaks by overlaying the data on aerial photography and GPS maps as well as to parse out emissions that are not associated with gas distribution (like landfill emissions). GML data includes leak height information, which is helpful for distinguishing ground leaks from those on the roof or sides of buildings. Add in leak rate quantification, and aerial scans have a clear advantage over ground patrols for facilitating and streamlining leak repairs.
Q: Detecting small leaks is critical for safety in the distribution sector. Can GML detect methane leaks at a meaningful scale?
Arrasmith: Yes, it can. For the distribution sector, we operate at an emission rate detection sensitivity of 0.5 kg/hr (about 25 scfh) with a 90% Probability of Detection (PoD) under typical conditions and assuming the emission is not obscured from view from the aircraft. This means we will typically catch, statistically, nine out of ten leaks at 0.5 kg/hr. We’ll catch plenty of smaller leaks too, but the likelihood becomes less as the emission rate gets smaller. We have worked with distribution utility partners to dial in our detection sensitivity to uncover the leaks that require immediate attention and are most valuable for emissions reduction in the sector.
Q: Can you describe more about the GML scans and how they’re set up?
Arrasmith: Typically, distribution infrastructure in cities is composed of a dense network of gas pipes–unlike the transmission sector where there is a single pipeline to follow. For the dense distribution networks, we typically use a gridded scan approach intended to cover all land area. In this way, we can ensure full coverage of the dense infrastructure. We even have ways to audit the actual ground swaths that our lasers have scanned. Each day, we tackle another grid area.
In cases where the infrastructure is sparse, such as a single distribution pipeline rather than in a dense network, we can scan over each pipe directly to cover only the areas where leaks are probable.
Q: What information is provided to GML clients?
Arrasmith: Bridger works with clients on the front end to design our scan areas and schedule scans to make sure their field crews can handle the workload generated from the GML data. If there are several operating districts, we typically rotate between them on a daily or weekly basis to provide a steady stream of follow-up to all districts. The processed report data products we generate include coordinates of each emission source identified, plume imagery, aerial photography from the time of scan, leak rate quantification, and other attributes. We typically deliver KMZ, PDF, and spreadsheet formats, and we can also create custom formats that integrate into a client’s GIS software. We aim to deliver our data in a format that is easily incorporated into our customers’ workflow so their crews can immediately act when they receive it.
Q: How would you describe a successful project with a distribution utility?
Arrasmith: While many distribution utilities already monitor their service area on a regular cadence using foot patrols, proactively scanning their service territory with GML provides best-in-class safety and emissions reduction. Distribution utilities already have workflows in place to investigate leaks based on ground patrols and reports from the public. We like to work with utility companies before and during deployment to make sure our data not only flows seamlessly into their existing workflows, but to make sure GML scans are scheduled to provide the useful data at a cadence that works for their field crews. For utilities with many different operation districts, we typically schedule scans in different areas each week, so ground crews have time to finish investigations before another scan over an adjacent area begins. Ultimately, a successful project involves good communication between Bridger and the customer to ensure GML data meets the client’s needs and is valuable for their leak detection and repair efforts.
Q: Any other thoughts you’d like to share?
Arrasmith: As an aerial scanning technique, GML measures methane via path-integrated concentration units (ppm-m) instead of point concentration units (ppm) like handheld sensors do. Since most existing patrols for distribution utilities are done with sensors that measure concentration at a single point, it’s important to understand the difference between the two measurements units. We have a great blog breaking down the difference between ppm and ppm-m here.
Because of the fundamental measurement difference, it’s often not easy to compare concentration values measured by GML to those measured by ground crews. Bridger’s algorithms let us calculate the actual flow rate (i.e. emission rate) in units of scfh or kg/hr, which is often a more meaningful metric to prioritize repairs and track emissions reduction than simply methane concentration, which can change drastically depending on wind conditions.
Chris received his bachelor’s and master’s degrees in Electrical Engineering from Montana State University and has more than thirteen years of experience in electronics, optics, and small business growth. During this time, he spent more than eight years growing an optics technology startup company. He loves the interface between the technical side of Bridger’s operations and working directly with Gas Mapping LiDAR clients to ensure project success. Chris is an avid outdoorsman, and when he is not helping his clients reduce their methane emissions, he spends his time hunting, rock climbing, camping, and hiking with his wife and children.
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