The Pipeline and Hazardous Materials Safety Administration (PHMSA) is tasked with regulating America’s vast network of pipelines to ensure a safe, reliable pipeline system. Recently, PHMSA proposed expanded methane leak detection requirements for gas pipelines. The rule focuses on bringing modern leak detection technology with all its benefits to already-regulated gas pipelines. This particular rule doesn’t expand leak detection requirements to previously-unregulated pipelines, instead it focuses on how to make leak detection requirements more effective and efficient.
The central issue in the proposed rule for many natural gas gathering companies will be the new Advanced Leak Detection Program (ALDP) requirements for larger gas gathering lines. Those lines, known as Type C gathering lines, are often located in rural areas and are at least 8.625” in diameter.
Companies will now need to develop rigorous, technology-based plans to inspect their pipelines for methane leaks at least annually, as well as expanded visual patrol programs to monitor pipeline integrity.
The comment period on PHMSA’s proposed rule closed on August 16th, 2023. Kairos submitted comments to help PHMSA further modernize how leak detection technologies get applied in the field. Our detailed technical comments cover the ins and outs, but we’ll hit the highlights for you here.
- PHMSA must lean into remote sensing technologies (like aerial leak detection), which can be deployed at low cost and at scale.
- The performance standard for remote sensing technologies should be purpose built for these sensors and their limitations, and PHMSA should provide more clarity on how and when it will approve technologies for regulatory use.
- PHMSA should reorient its proposal towards performance-based regulation. Currently, the proposed rule doesn’t have a mechanism to weigh costs and benefits of various leak sensing technologies, each of which have their own strengths and drawbacks. It instead applies a single one-size-fits-all standard that is inefficient and too prescriptive.
What kinds of performance standards do remote sensing technologies need?
The proposed PHMSA rule creates a default standard that would require companies to inspect pipelines for leaks using cumbersome handheld devices that must be used on foot close to the pipeline. It’s a slow, costly, and inefficient way to find leaks. PHMSA establishes a performance standard for these technologies to measure leak concentrations in parts per million (ppm).
The problem with ppm is that it’s a measurement of a concentration at a specific point at a specific time. It tells us nothing about the size of a leak—all it can tell us is the concentration of gas in a discrete pocket of air.
Many remote sensing techniques cannot measure concentration, because concentration measurements require “sniffing” of the air in the immediate vicinity of the leak. Instead, remote sensing measurements are taken from thousands of feet away, and they cannot use sniffing-style measurement techniques.
Remote sensing systems need a flow-based performance standard, such as kilograms per hour or cubic feet per hour. Remote sensing systems are much better suited to measure emission rates. It’s worth noting in the US Environmental Protection Agency (EPA)’s proposed methane regulations for the oil and natural gas sector, the performance standard for remote sensing systems utilizes kilograms per hour. We’re encouraging PHMSA to take a similar approach to EPA.
How can PHMSA write a more cost-effective rule?
It’s easy to sit back and argue that a particular regulation or policy isn’t cost effective, but to come up with a proposal that balances costs and benefits is a more difficult matter. And we’ve come up with a proposal for PHMSA we think does just that.
The first step is for PHMSA to explore what emissions data tell us about gas pipeline leaks. Are they big? Small? Common? Rare? We’ve looked at several scientific studies using both remote sensing techniques to catch the big leaks and ground-based sensing techniques to catch the small leaks, as well Kairos’ own data on over 95,000 miles of pipelines. We used these data sources to come up with an expected spectrum of leaks. Together, they us that small leaks exist, but big leaks absolutely dominate the total amount of methane being emitted. And when we say big, we’re talking about emissions of 100 to several hundreds of kilograms per hour (kg/hr). Kairos has a 90% chance to see leaks of 10 kg/hr, but the science tells us leaks much bigger than that drive most methane losses.
We used that leak spectrum and then compared various leak detection programs using LDAR-Sim, a peer-reviewed emissions modeling tool developed by Highwood Emissions Management.
We modeled a ground-based leak detection program that could identify 100% of emissions, which is better than these instruments typically perform in the field, but was designed to give an “absolute best case” of performance for PHMSA’s proposed ALDP (annual surveys with a handheld instrument). We then compared that to a remote sensing leak detection program using 10 kg/hr sensitivity, 30 kg/hr, and 50 kg/hr. The results, shown in the table below, make clear that advanced technology can offset more emissions.
|Percent of Emissions Reduced by Technology
|# of Surveys per Year
|Remote Sensor –
|Remote Sensor –
|Remote Sensor –
Table 1 – LDAR-Sim modeling results for an ideal hand-held sensor employed once per year compared to modeling results for a variety of remote sensing survey strategies. Percentages show the fraction of total yearly methane emissions mitigated by each survey strategy.
The last input is survey cost. EPA found that ground-based leak surveys were anywhere from 10 to 15 times more expensive than remote sensing surveys in its proposed oil and gas methane standards. It therefore stands to reason that a program using two remote sensing surveys would cost much less than one ground-based inspection, given those cost differentials. And better yet, that remote sensing program would reduce more emissions overall.
What does all this mean?
PHMSA’s proposal needs some work, but it can absolutely create a regulatory regime that protects health and the environment while minimizing burden to the regulated community. They need to broaden the lens through which they look at technologies, and refine their cost-benefit analysis, and our comments are designed to help them do both of those things.