[Federal Register Volume 89, Number 168 (Thursday, August 29, 2024)]
[Notices]
[Pages 70177-70181]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-19403]


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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2024-0350; FRL 12138-01-OAR]


Use of Advanced and Emerging Technologies for Quantification of 
Annual Facility Methane Emissions Under the Greenhouse Gas Reporting 
Program

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice; request for information (RFI).

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[[Page 70178]]

SUMMARY: The EPA invites public comment on the potential for expanded 
use of advanced and emerging technologies for methane emissions 
quantification in EPA's Greenhouse Gas Reporting Program (GHGRP). These 
technologies are an important part of EPA's GHGRP, including under the 
recently finalized amendments for Petroleum and Natural Gas Systems. 
EPA intends to use the feedback received in response to this RFI to 
consider whether it is appropriate to undertake further rulemaking 
addressing the use of advanced measurement technologies in the GHGRP 
for petroleum and natural gas systems and municipal solid waste (MSW) 
landfills, beyond the current role provided in existing rules for these 
technologies.

DATES: Comments must be received on or before October 28, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2024-0350, to the Federal Portal: https://www.regulations.gov. 
Follow online instructions for submitting comments. Once submitted, 
comments cannot be edited or withdrawn. Do not submit electronically 
any information you consider to be Confidential Business Information 
(CBI). EPA may publish any comment received to its public docket, 
submitted, or sent via email. For additional submission methods, the 
full EPA public comment policy, information about CBI, and general 
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Vasco Roma, Environmental Protection 
Agency, Office of Air and Radiation, Office of Atmospheric Protection, 
Climate Change Division; telephone number: 202-564-1662; email address: 
[email protected].

SUPPLEMENTARY INFORMATION:

I. Background

    Technologies with the ability to detect and measure atmospheric 
methane have been advancing significantly over the last few decades. 
These technologies are an important part of EPA programs, including the 
recently finalized 40 CFR part 98 Subpart W (Subpart W) amendments, 
which allow for the use of advanced measurement technologies to help 
quantify methane emissions from Petroleum and Natural Gas Systems 
sources, such as emissions from other large release events and flares 
under the GHGRP.\1\ Similarly, the oil and natural gas New Source 
Performance Standards and Emission Guidelines at 40 CFR part 60 
Subparts OOOOb and OOOOc (``NSPS OOOOb/EG OOOOc'') published in March 
2024 allow for the use of advanced measurement technologies to identify 
the presence of Super Emitter Events and for detecting fugitive 
emissions.\2\ In addition, the rules provide a pathway for 
demonstrating that new technologies meet the performance requirements 
established in the NSPS/EG rules. As a result, regulated entities are 
able to leverage advanced measurement technologies that are already 
available to detect methane emissions rapidly with accuracy, as well as 
to incorporate new technologies that are emerging in this rapidly 
evolving field.
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    \1\ Final Greenhouse Gas Reporting Rule: Revisions and 
Confidentiality Determinations for Petroleum and Natural Gas 
Systems, 89 FR 42062 (May 2024).
    \2\ Final Standards of Performance for New, Reconstructed, and 
Modified Sources and Emissions Guidelines for Existing Sources: Oil 
and Natural Gas Sector Climate Review, 89 FR 16820 (March 2024).
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    Following requests for comment in the notice of the 2023 proposed 
rulemaking for Subpart W,\3\ the EPA received numerous comments 
requesting that the use of advanced measurement technologies be allowed 
to quantify emissions from other sources beyond other large release 
events in Subpart W. In response to these comments, EPA reviewed remote 
sensing and in situ advanced measurement approaches (including both 
intermittent and continuous monitoring approaches) that utilize 
information from satellite, aerial, drone, vehicle, and stationary 
platforms to detect and/or quantify methane emissions from oil and gas 
operations for their potential use in Subpart W reporting. As a result 
of this review and in response to comments on the proposed Subpart W 
rule, in May 2024, EPA finalized additional options within Subpart W to 
use advanced measurement technologies to measure data that are inputs 
to emission calculations for flares and well completions and workovers, 
in addition to the proposed use of advanced measurement technologies to 
quantify emissions from other large release events and/or estimate the 
duration of such events.
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    \3\ Proposed Greenhouse Gas Reporting Rule: Revisions and 
Confidentiality Determinations for Petroleum and Natural Gas 
Systems, 88 FR 50282 (August 2023).
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    As EPA acknowledged in the final Subpart W rule, advanced 
measurement technologies are developing rapidly and are particularly 
well-suited for detecting and quantifying large and discrete emissions 
events, such as other large release events. Based on EPA's assessment 
of the strengths and limitations of advanced measurement technologies 
at the time of finalizing the Subpart W rule, however, EPA limited the 
use of these technologies in annual GHG reporting to certain specific 
roles identified in the final rule.\4\
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    \4\ Final Greenhouse Gas Reporting Rule: Revisions and 
Confidentiality Determinations for Petroleum and Natural Gas 
Systems, 89 FR 42062 (May 2024).
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    EPA has also sought comment on how methane monitoring technologies 
might enhance emission estimates for other industrial sectors covered 
under the GHGRP, specifically for MSW landfills under 40 CFR part 98 
Subpart HH (Subpart HH). In a May 2023 notice of proposed rulemaking, 
EPA requested examples of methane data collected from available 
monitoring methodologies and how such data might be incorporated into 
quantifying annual emissions.\5\ Although the EPA did not take final 
action to incorporate advanced measurement technologies in the April 
2024 final rule for the reasons described therein,\6\ including 
information in comments received noting limitations in existing 
technologies, EPA has continued to review ways to incorporate the use 
of advanced measurement technologies into the emissions reporting for 
MSW landfills for GHGRP reporting purposes under Subpart HH.
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    \5\ Proposed Revisions and Confidentiality Determinations for 
Data Elements Under the Greenhouse Gas Reporting Rule, 88 FR 32852 
(May 2023).
    \6\ Final Revisions and Confidentiality Determinations for Data 
Elements Under the Greenhouse Gas Reporting Rule, 89 FR 31802 (April 
2024).
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    Based on these reviews, EPA recognizes that advanced measurement 
technologies, and their use for annual quantification of methane 
emissions, are evolving rapidly. EPA is committed to transparent and 
continual improvements to its programs to ensure reporting is accurate 
and complete. There are four key considerations associated with 
expanding the use of advanced measurement technologies to quantify 
annual methane emissions \7\ under the GHGRP in a robust, transparent, 
accurate, standardized, and verifiable way:
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    \7\ Current GHGRP reporting requires quantification of methane 
emissions at the equipment-, process-, or facility-level. For 
example, under Subpart W emissions are quantified and reported for 
specific equipment types, such as pneumatic controllers. For Subpart 
HH, emissions are quantified and reported at the facility-scale, 
which includes the total surface area of the landfill, or for 
specific processes such as landfill gas collection and control 
systems.

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    (1) How to translate the measurement data provided by different 
types of advanced measurement technologies (e.g., methane plume images, 
satellite retrievals of column methane mixing ratios, ambient methane 
concentrations) into total tons of methane emissions.
    (2) How to extrapolate methane emissions from discrete and 
intermittent observations into total methane emissions throughout the 
year (with a specific level of accuracy) and attribute these emissions 
to a specific equipment type, process, or facility.
    (3) How to identify, attribute, and quantify methane emission 
events that are below a technology's detection limit, in order to 
estimate total equipment-, process-, or facility-level emissions 
throughout the year.
    (4) How to set detection, quantification, attribution, 
verification, and uncertainty criteria and/or protocols for different 
types of advanced measurement technologies to ensure implementation 
into the GHGRP in a manner that is applicable to different 
infrastructures and environmental conditions across the U.S. (e.g., 
topographies, climates, facility types and layouts).
    As technologies continue to rapidly advance to meet these needs, 
EPA is issuing this RFI to the public to obtain information about 
currently available advanced and emerging methane measurement 
technologies, and how these technologies could be used to quantify 
annual methane emissions from the oil and gas and MSW landfill industry 
segments at the equipment-, process-, or facility-level for GHGRP 
reporting purposes. The following questions are aimed to address the 
key considerations outlined above and have been organized into the 
following categories: quantification, attribution, and implementation.
    EPA believes that standards or protocols could help ensure the use 
of advanced measurement technologies to quantify annual methane 
emissions is implemented in a transparent and standardized manner. 
Furthermore, EPA anticipates that annual quantification approaches may 
be specific to an emission source, facility type, or type of 
technology. Therefore, a potential standard or protocol might be 
specific to a type of methane source (e.g., hydrocarbon liquid storage 
tanks, landfill working face) and a specific measurement approach 
(e.g., drone, aircraft, vehicle-based, or multi-platform based). For 
example, for a specific type of source, a potential standard or 
protocol might include a detection limit below a certain methane 
emissions rate threshold, a sampling frequency and duration (e.g., 1 
overpass weekly) to ensure representative sampling of operating 
activities throughout the reporting year, the inclusion of specific 
ancillary data (e.g., wind speed and direction), and the use of a 
transparent and peer-reviewed methodology (e.g., inverse analysis, 
statistical sampling) to quantify the annual total methane emissions to 
within a specified level of accuracy (e.g., 90%). To the extent that 
information provided in response to the questions below are specific to 
a particular emissions source, facility type, or technology type, 
please indicate the applicability in the comments provided.

II. Questions

1. Quantification of Annual Emission Rates

    EPA is requesting information on issues related to the 
quantification of methane emissions using currently available advanced 
measurement technologies, including: (1) detection and quantification 
of methane emission rates; (2) approaches for extrapolating 
observation-based methane emission rates to estimate annual total 
emissions; and (3) approaches for quantifying annual total methane 
emissions for sources that emit at rates below technology minimum 
detection thresholds. Detailed questions on each topic are listed 
below. Please provide detailed answers and citations to relevant 
resources.
a. Detection and Quantification of Atmospheric Methane Emission Events 
From Advanced Measurement Technologies
    Advanced technologies for methane detection, such as instruments 
deployed on satellite, aircraft, or in the form of continuous monitors, 
can be used to detect methane emissions. These technologies do not 
directly quantify methane emission rates but require additional 
analytical tools and methods to transform the raw sensor measurements 
(e.g., change in light attenuation) into quantified methane emission 
rates (e.g., kg/hour) associated with each observation. Quantification 
approaches can include but are not limited to the inverse analysis of 
observed concentrations, the use of dispersion modeling, co-emitted 
tracer releases, or mass balance approaches. Based on the wide variety 
of detection and quantification approaches currently available, EPA 
requests comment on the following:
    i. What advanced measurement technologies are currently available 
that can provide quantified methane emission rates using transparent, 
open-source, and standardized methodologies? What are the specific 
quantification approaches that have been used with these technologies, 
and how have these methodologies been demonstrated and validated? How 
can these technologies and quantification methodologies be used to 
provide annual data in a consistent manner for each future year of 
GHGRP reporting? Are there specific detection and quantification 
approaches or methodologies that EPA should or should not consider?
    ii. What performance metrics and threshold(s) related to 
quantification would be appropriate to apply to advanced measurement 
technologies for their incorporation into the GHGRP? For example, 
should EPA consider: thresholds for the methane detection limit (e.g., 
minimum emissions leak rate), thresholds for the probability of 
detection (e.g., rate of false positives or negative detections), 
specific levels of accuracy for quantification, specific measurement 
frequencies, or other? What would be a feasible approach for developing 
these thresholds and metrics?
    iii. Should quantification approaches be limited to the use of 
specific methodologies (e.g., inverse analysis, mass balance) or 
specific approaches for using ancillary datasets (e.g., standardized 
interpolation of wind field products)?
    iv. Are there ongoing efforts outside of EPA to develop standards 
or protocols for methane emissions detection and quantification from 
advanced measurement technologies that would address any of the 
questions raised in this RFI? If so, please specify which efforts and 
which question(s) can/will be answered and when these standards or 
protocols will be publicly available.
b. Extrapolating Quantified Methane Emission Rates To Calculate Annual 
Emissions for GHGRP Reporting Purposes
    Different advanced measurement technologies provide data at 
different sampling frequencies (e.g., continuous to weekly) and 
durations (e.g., seconds to hours). Depending on the type of technology 
and emissions source sampled, different approaches have been used to 
extrapolate observation-based methane emission rates to estimate total 
annual emissions for a specific region, facility, or site. These 
approaches often require additional information on the frequency and 
duration of the sampled emission events, information on the population 
of sampled emission sources, site-specific

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operational activities, or statistical analytical approaches. EPA seeks 
comment on the following:
    i. What advanced measurement technologies are currently available 
that can provide annual total methane emission estimates for specific 
regions, facilities, processes, or equipment-level sources, that use 
transparent, open-source, and standardized methods? Are these 
technologies applicable across the entire U.S. and could they provide 
annual data in a consistent manner for each future year of GHGRP 
reporting? Are there specific annual extrapolation approaches or 
methodologies that EPA should or should not consider?
    ii. What accuracy or uncertainty metrics would be appropriate for 
GHGRP reporting purposes? For example, what level of accuracy in 
reported annual methane emissions should advanced measurement 
technologies be required to meet? What sources of uncertainty are 
necessary to consider? Are there other specific quality assurance or 
quality control markers that should be considered to ensure that annual 
estimates represent the methane emissions from all operational 
activities throughout the reporting year, such as specific measurement 
frequencies or duration? What would be a feasible approach for 
developing these thresholds and metrics?
    iii. To what extent should standards and protocols be specific to 
the type of methods and ancillary data used (e.g., statistical 
approaches), and to what extent should standards and protocols 
simultaneously consider the specific type of emission sources being 
sampled (e.g., large unintended vs. small routine emissions event)?
c. Quantifying Annual Methane Emissions From Emissions Sources Below 
Detection Limits of Advanced Measurement Technologies
    Different advanced measurement technologies also have different 
detection thresholds (e.g., ~1 kg/hr to above 100 kg/hr), in part 
dependent on the distance of the instrument from the source (e.g., 
typically larger detection limit for instruments on satellites compared 
to aircraft), instrument type, and sampling strategy. In the current 
GHGRP, a significant number of sources emit methane at rates below 
these typical detection limits (e.g., a component leak will typically 
emit at rates significantly below 1 kg/hr). To account for methane 
emissions from these additional sources, various methodologies and 
statistical approaches have been developed to estimate total annual 
emissions to complement the data collected from advanced technology 
measurements. EPA seeks comment on the following:
    i. What methodologies are currently available for integrating 
estimates of methane emissions for those sources emitting below 
technology detection thresholds in an open-source, transparent, and 
standardized way? Can these methodologies provide annual data in a 
consistent manner for each future year of GHGRP reporting? Are there 
specific approaches or methodologies that EPA should or should not 
consider?
    ii. Should these quantification approaches be limited to the use of 
specific methodologies (e.g., Monte Carlo method) or specific ancillary 
datasets (e.g., the use of standardized infrastructure or operator 
data)?

2. Attribution

    EPA is requesting comment and information regarding attribution of 
quantified methane emissions (from discrete events or annual totals) to 
specific GHGRP facilities, sites, or sources.
    In addition to differences in temporal resolution, advanced 
measurement technologies have spatial resolutions that can range from 
kilometers (e.g., satellite) to site or individual equipment scales 
(e.g., ground-based sensors). There are different approaches for 
attributing observed events to a specific equipment type, process, or 
facility depending on the specific type of technology used and sampling 
distance from the emissions source. These approaches often require 
ancillary information such as infrastructure data, site operator data, 
or meteorological data such as wind speed and direction. EPA seeks 
comments on the following:
    a. What methodologies are currently available that can attribute 
quantified methane emission events to specific equipment types (or 
additionally, specific regions, facilities, or processes) using 
transparent, open-source, and standardized methods? Are there specific 
attribution approaches or methodologies that EPA should or should not 
consider?
    b. What accuracy or uncertainty metrics would be appropriate for 
GHGRP reporting purposes? For example, what level of confidence in the 
source attribution would be necessary for advanced measurement 
technologies to meet for GHGRP reporting purposes? What would be a 
feasible approach for developing these thresholds?
    c. To what extent would standards and protocols need to be specific 
to the type of methods and ancillary data used (e.g., infrastructure 
datasets) or the type of emission source sampled (e.g., large 
unintended vs small routine emissions event)?

3. Implementation

    EPA is requesting comment and information on issues related to the 
implementation of advanced measurement technologies into the GHGRP.
    Implementation considerations include the need for quantifying 
annual total methane emissions from oil and gas and MSW landfill 
applicable sources across the U.S. in a transparent and standardized 
way, validation and verification of the reported data, and additional 
potential uses of advanced measurement technologies for the GHGRP. EPA 
also requests information on additional data that could be reported for 
the verification of methane emissions estimates produced using advanced 
measurement technologies.
a. Structure of Approaches or Protocols
    i. What form would standard method(s) or protocol(s) need to take 
to ensure that advanced measurement technologies provide annual total, 
source-specific, methane emissions in a transparent and standardized 
way? For example,
    (1) To what extent should standards and protocols be specific to 
the type of methods used (e.g., satellite, aircraft, ground-based)? In 
addition, would different standards or protocols be necessary for 
sampling approaches using single platform vs. multi-platform 
measurements? Could standard methods be developed to be technology 
agnostic?
    (2) To what extent could standard method(s) be developed to be 
source agnostic? For example, would standards need to be specific to 
the type of equipment, process, or emission source sampled (e.g., 
tanks, flares, pneumatic devices, landfill working face), or could a 
set of standard(s) be developed to be more broadly applicable across 
different GHGRP industry segments (e.g., oil and gas operations and 
landfills)? Alternatively, would different standards be necessary for 
different types of methane emission events sampled (e.g., large 
unintended vs small routine emissions events)?
b. Verification and Validation of Annual Source-specific Methane 
Emission Quantification Methods Using Advanced Measurement Technologies 
for GHGRP Reporting Purposes
    i. Are there approaches currently available that could be used to 
verify that advanced measurement technologies meet specific standards 
(e.g., independent blind studies,

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deployment of calibration standards, other)?
    ii. Is it necessary to limit the applicability of advanced 
measurement technologies to environmental and site conditions that have 
been previously validated? For example, if an advanced measurement 
technology has been validated through blind control release testing 
during which wind speeds ranged from 0.5 to 10 m/s, should the 
technology be limited to measurements within this range of wind speeds? 
What form of validation could be used to demonstrate whether a 
technology is applicable across environmental conditions outside of 
their tested ranges?
    iii. Are there specific types of operator- or facility-specific 
information that would be useful for improving or validating annual 
methane emissions quantification or source attribution from advanced 
measurement technologies?
c. Other Considerations Related to the Use of Advanced Measurement 
Technologies for GHGRP Reporting Purposes
    i. What (if any) are the current barriers or limitations to using 
advanced measurement technologies beyond what is currently allowed 
under the GHGRP to quantify annual equipment-level methane emissions at 
scale in the U.S.?
    ii. What are the cost considerations for implementing different 
advanced measurement technologies to quantify annual, equipment-, 
process-, or facility-level methane emissions for GHGRP reporting 
purposes? If available, costs should be provided in a manner that can 
be scaled up to different implementation approaches (e.g., cost per 
site, cost per area covered).
    iii. How are factors such as measurement and analysis cost, 
complexity, or time burden relevant for determining whether advanced 
measurement technologies may be appropriate for annual GHGRP 
application?
    iv. Other than methane emissions detection and quantification, and 
establishing the duration of emission events as permitted under Subpart 
W for Other Large Release Events, are there additional ways in which 
advanced measurement technologies could be used to support 
quantification and reporting of equipment-, process-, or facility-level 
methane emissions to the GHGRP (e.g., as a method to identify changes 
in operating conditions, to supplement specific reported data 
elements)?

Sharyn Lie,
Director, Climate Change Division.
[FR Doc. 2024-19403 Filed 8-28-24; 8:45 am]
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