A Summary of Bridger's Comments on the EPA's Latest Methane Rule
Upon the U.S. EPA’s December 2022 release of the Supplemental Notice of Proposed Rulemaking – Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review, the agency solicited comments regarding the rule. Bridger Photonics appreciated the opportunity to submit comments.
Bridger’s combined operational and scientific knowledge uniquely situates us to provide feedback on how aspects of the Proposed Rule can be adjusted to advance the stated goals of the EPA. These goals include to “significantly reduce emissions of greenhouse gases and other harmful air pollutants from the Crude Oil and Natural Gas source category” and to “minimize any significant economic impact of the proposed rule [on the O&G industry].”
In Bridger’s letter, we provided recommendations that will help the EPA fortify its regulatory framework for emissions monitoring technologies, improve the performance-based technology agnostic nature of the regulation, and reward technologies for improved performance. Our comments were centered on five areas:
- Requirements for emissions detected by advanced technologies
- Emissions monitoring approach equivalency determination
- The periodic screening matrix
- Recommendations for the alternative test method approval process
- Additional points that need clarification
The following is a summary of Bridger Photonics’ comments. Access the full version with additional detail at the bottom of this page.
Comment Area 1: Requirements for Emissions Detected by Advanced Technologies
- The response to emissions detected using an alternative test method must be situationally appropriate. The “blanket” follow-up OGI survey for emissions detected by advanced technology in the periodic screening matrix is an ineffective approach to mitigating emissions. Advanced technologies may detect, record, and characterize many emission sources for which OGI follow-up is unnecessary, unhelpful, and/or impractical. A mandatory OGI sweep will create a disincentive for operators to deploy advanced technologies for compliance with the Proposed Rule by causing an undue burden when it is not an appropriate or useful response. Compared to a universal OGI follow-up requirement, a better approach to responding to emissions will often involve investigative analysis using a combination of advanced technology data (Figure 1), compressor runtime data, process control/SCADA data, maintenance activity logs, AVO inspection, and prior screening results.
Figure 1. Examples of several emission types routinely detected by Bridger’s Gas Mapping LiDAR™ (GML) technology and demonstration of certain GML data attributes. Emission sources can often be clearly identified, and a variety of metadata is provided for causal analysis. Due to confidentiality requirements, the dataset shown is synthetic but it is representative of field measurements.
- When OGI follow-up for emissions detected using advanced technology is appropriate, it should be guided by the emission source localization performance of the technology. We urge the EPA to refine the periodic screening OGI follow-up requirement to correspond to the localization performance of the methane sensing technology that originally detected the emission (i.e., if a technology localizes at the equipment level, OGI follow-up is required on that piece of equipment where an emission was detected, not across the entire site). Localization performance should be defined based on established precedent, with precision being defined at site level, equipment group level, equipment unit level, and component level.
- Requirements for emissions detected by advanced technology should be uniform (i.e., technology agnostic). Although the Proposed Rule requires follow-up OGI screening for emissions detected during periodic screening, equivalent requirements are not delineated for the alternative continuous monitoring program, which damages the intended technology-agnostic nature of the rule. The scope of OGI surveys should correspond to the localization capabilities of the continuous monitoring methods, since continuous monitoring systems localize emissions with different degrees of precision, as characterized by independent researchers. To maintain consistency and be technology agnostic, we urge the EPA to include the same OGI follow-up requirements for the continuous monitoring alternative approach as for the periodic screening alternative approach.
- The EPA should incentivize the detection and mitigation of compliance issues identified by advanced technologies. Due to the more comprehensive spatial and temporal coverage of advanced technologies, considerably more emission sources may be revealed that represent compliance issues as compared to standard OGI surveys. Examples of such sources include malfunctioning control devices as well as cover and closed vent system failures. Such additional risk of incurring violations strongly disincentivizes the use of effective and comprehensive detection technologies. We urge the EPA to provide a compliance pathway for compliance issues detected by advanced technologies to remove disincentives for detecting emissions.
- An extended repair deadline is appropriate for periodic screening. The 30-day timeline for repairing emissions detected during periodic screening does not allow operators enough time to follow up on detected emissions. Certain advanced methane sensing technologies that will be used for periodic screening can cover 100+ sites in a single day. This level of efficiency is a major reason that operators benefit from access to these technologies. Compared to the ~5 sites per day that can be screened by OGI, efficient aerial screening would generate a much larger workload of follow-up repairs in a short period of time. It is also necessary to consider time needed for data to be fully processed before it is delivered to operators. We urge the EPA to allow 45 days after site screening to complete repairs on emission sources detected during the periodic screening alternative approach.
Comment Area 2: Emissions Monitoring Approach Equivalency Determination
- The EPA should correct and validate FEAST modeling inputs using new emission rate distributions. Since the November 2021 proposal, significant research has been made public that bears critical implications for modeling the performance of different emissions monitoring approaches. For example, Bridger recently submitted a paper for publication that describes an emission rate distribution measured in the Permian Basin with continuous coverage from large emission rates down to rates below 2 kg hr-1. Preliminary investigation of FEAST simulations suggests that the equivalency determinations could be made more accurate by referencing simulations against Bridger's extensive emission rate distribution. We urge the EPA to correct and validate FEAST modeling using the best available data in a publicly transparent process prior to finalizing rules for alternative emissions monitoring.
- OGI should be compared to alternative emissions monitoring approaches using equivalent definitions of detection sensitivity. The EPA’s regulatory framework for emissions monitoring with advanced technology is based on the notion that technologies are qualified based on field performance. However, monitoring options are compared to a model for OGI monitoring which has inputs that may incorrectly represent field performance. This is because studies indicate that the performance of OGI is subject to user experience and OGI may not provide complete spatial coverage. We urge the EPA to simulate emissions reductions provided by OGI emissions monitoring programs using inputs that are representative of actual OGI field performance.
Comment Area 3: Periodic Screening Matrix
- The periodic screening alternative approach should be flexible to address seasonal environmental challenges. Seasonal environmental conditions such as snow cover, high winds, or solar radiation levels need to be considered for emissions monitoring because they can adversely affect methane detection performance. Making sure that different periodic screening detection sensitivity tiers can be applied within a single LDAR monitoring plan during different periods of time would help operators in regions with seasonal environmental challenges to achieve regulatory compliance. We urge the EPA to make it clear that detection tiers may be selected on a quarterly basis.
- The EPA can base emissions monitoring options entirely on their performance. OGI inspections and Method 21 are methane emissions screening approaches that would fit into the periodic screening framework in the Proposed Rule. We urge the EPA to implement a single technology-agnostic framework for all emissions monitoring approaches with performance attributes well characterized for field deployment.
- The periodic screening tier with 30 kg hr-1 detection sensitivity is inconsistent with continuous monitoring action thresholds and too weak to achieve equivalence. Requirements for continuous monitoring and periodic screening require greater consistency. The Proposed Rule specifies continuous monitoring short-term action levels of 14 kg hr-1 and 21 kg hr-1 for site-level emissions at single well sites and more complex sites, respectively. Meanwhile, the periodic screening matrix allows less frequent monthly screening (+ annual OGI) using a method that achieves less sensitive 30 kg hr-1 detection sensitivity (90% PoD). To resolve the inconsistency between the continuous monitoring sensitivity requirements (14 or 21 kg hr-1 short-term action levels) when compared to monthly periodic screening with 30 kg hr-1 detection sensitivity, and to account for the variation in basin-specific emission rate distributions, we urge the EPA to remove the 30 kg hr-1 periodic screening detection tier.
Comment Area 4: Recommended Aspects of the Alternative Test Method Application
- Third-party blind testing using standard protocols is necessary to provide confidence in the capabilities of methane sensing technologies. To ensure that the alternative test method approval process is transparent and upholds high scientific standards, blind testing by an approved third party should be required to demonstrate detection sensitivity. The METEC Advancing Development of Emissions Detection (ADED) initiative provides defined blind testing protocols for both continuous emissions monitoring systems and periodic screening methods. We urge the EPA to require methane sensing technologies specified in alternative test method applications to demonstrate detection sensitivity performance through third-party blind testing using ADED protocols as part of approval requirements.
- Emission source localization capabilities should be demonstrated in the alternative test method application. Fundamental properties of methane sensing technologies include the ability to detect, localize, and quantify emissions. Localization capabilities should guide operators’ response to detection events. Technologies used for emissions monitoring should be able to localize emissions at least to the site level. Improved localization capabilities should be reported as equipment group, equipment unit, and component-level precision. We urge the EPA to require demonstration of emission source localization capabilities through third-party blind testing using ADED protocols.
- Methane sensing technologies need to reliably quantify emissions. In the proposed rules, mass emission rate action levels for the continuous monitoring approach assumes that the methane sensing technology accurately quantifies emissions. An alternative test method should not be approved by the EPA unless its capabilities are well represented. Quantification is also crucial for the periodic screening approach because mass emission rates are needed to generate emission rate distributions, which provide direct insight to the detection sensitivity actually realized during field measurements. We urge the EPA to require demonstration of emission rate quantification capabilities for all technologies specified in alternative test method applications through third-party blind testing using ADED protocols.
- Meaningful detection sensitivity performance metrics should be required for continuous monitoring systems. The Proposed Rule indicates that the detection sensitivity of continuous monitoring systems should be an order of magnitude smaller than the action levels specified for the continuous monitoring approach. However, the performance metric for sensitivity is not defined. We recommend that detection sensitivity is defined as the emission rate at which the technology has a 90% probability of detecting emissions, consistent with the requirements for periodic screening technologies. Using minimum detection levels is not suitable because it may have little bearing on field performance.
- To provide stakeholders with assurance that emission monitoring achieves stated performance, monitoring methods should be routinely audited. Operators, the EPA, and other stakeholders need assurance that emissions monitoring approaches continue to achieve their stated detection sensitivity. We recommend that the EPA requires sensor operators to report anonymized emission rate measurements in the aggregate for each production basin on a yearly basis. This data would be used by the EPA to evaluate the detection sensitivity achieved during field deployment.
Comment Area 5: Additional Points That Need Clarification
- The EPA should clarify that advanced technologies can be used in the place of both OGI and AVO inspection requirements. It is our understanding that it is the EPA’s intent to enable both the periodic screening and continuous monitoring alternative approaches to replace both OGI and AVO inspection requirements for any affected well site, compressor station, or centralized production facility. However, this provision was difficult to understand in the Proposed Rule preamble. We urge the EPA to make it clear throughout the preamble and in the regulatory text that periodic screening and/or continuous monitoring alternatives may replace both OGI and AVO inspection requirements in fugitive programs.
- The EPA should clarify that advanced technologies can be used to verify all zero emission requirements at sites where they will be used for emissions monitoring. It is our understanding that it is the EPA’s intent to enable both the periodic screening and continuous monitoring alternative approaches to provide compliance verification of zero emission numerical requirements for any affected facility at any well site, compressor station, or centralized production facility. However, this provision was difficult to understand in the Proposed Rule preamble. We urge the EPA to make it clear throughout the preamble and in the regulatory text that both periodic screening and continuous monitoring alternatives can be used instead of OGI for compliance verification of any zero emission requirements for affected facilities at well sites, centralized production facilities, and compressor stations.
Read Bridger Photonics’ full comment letter linked here:
Do you have a question about any of the comments made here? Please feel free to reach out to the Bridger Photonics team by filling out this form or sending us an email at info[at]bridgerphotonics.com.