Advances in Satellite Methane Emissions Measurement

Updated February 13, 2025

Advances in Satellite Methane Emissions Measurement

This In Focus discusses the role of evolving satellite

technologies, their ability to monitor methane and identify

large-scale emissions events, and how data from these

detection technologies fit into federal methane rules and

programs. Interest in detecting methane and observing and

locating emissions events stems in large part from efforts to

reduce the release of greenhouse gases (GHGs). In

particular, advances in remote sensing of methane from

satellites may improve monitoring and detection of methane

emissions from oil, coal, and natural gas operations.

Congress may consider the use of satellite methane

emissions information in U.S. programs.

Background on Methane Emissions

Methane has a global warming potential 27-30 times greater

than carbon dioxide over a 100-year period. It is second

only to carbon dioxide in contributions to global

temperature increases from human emissions of GHGs.

Fossil-fuel-related industries are among the sectors that

emit methane into the atmosphere. Some stakeholders

support reducing methane emissions as part of efforts to

mitigate climate change and to improve public health.

Regulation of methane emissions has been opposed by

other stakeholders for reasons of cost, among others.

Fugitive emissions are generally described as unintended

leaks from pressure containment systems, which can

include leaks from valves or flanges, in fossil fuel facilities.

Fugitive emissions also include methane that escapes to the

atmosphere from incomplete combustion during flaring (the

burning of excess gas).

Regulatory and Policy Context

Under the authority of Section 111 of the Clean Air Act

(CAA), the U.S. Environmental Protection Agency (EPA)

promulgated more stringent standards for methane

emissions from oil and natural gas facilities. Specifically, it

published a rule that finalized revisions to the new source

performance standards (NSPS) and emission guidelines

(EG). The rule requires states to submit and implement

plans to establish performance standards that limit GHG

emissions from existing oil and natural gas facilities (89

Federal Register 16820, March 8, 2024).

One set of actions in the 2024 rule is lessening fugitive

emissions by constraining them from large emissions

sources known as super-emitters. The rule established

standards for methane release events greater than 100

kilograms per hour, known as super-emitter events. The

rule also established the Methane Super Emitter Program to

allow certified third parties to submit data on methane

release events to the EPA Super Emitter Portal (as defined

in the final rule). Under this program, certified third-party

submitters may only use EPA-approved technology, which

includes (1) satellite detection of methane emissions, (2)

remote-sensing equipment located on aircraft, or (3) mobile

monitoring platforms. This rule adds to previous actions on

methane emissions. In accordance with CAA Section 111,

the Crude Oil and Natural Gas source category was first

listed as a source category subject to performance standards

in 1979. EPA’s 2016 rule expanded the emission sources

covered by the 2012 rule and added performance standards

for methane emissions.

Satellite measurement of methane emissions can contribute

to meeting U.S. treaty obligations under the United Nations

Framework Convention on Climate Change (UNFCCC).

This includes an annual Greenhouse Gas Inventory that

includes methane. On January 20, 2025, President Trump

issued an executive order directing the withdrawal of the

United States from agreements under the UNFCCC.

Methane Emissions Estimation Methods

Comprehensive measurement and estimation of methane

emissions is difficult, and the measurement technologies

continue to evolve. Methane emissions estimation methods

are often placed in two general categories. One type of

methods, sometimes referred to as “bottom up” (BU),

extrapolates measurements from individual natural gas

facility components to estimate total emissions for

industrial facilities. BU methods rely on averaging

numerous leak test measurements of these components to

develop “emissions factors.” These emissions factors are

used to estimate emissions for facilities based on the

number and types of components and the levels of

production. However, because emissions factors are based

primarily on leakage measured under normal conditions,

they may not fully account for super-emitter events and

may understate total emissions.

The second type of methods, referred to as “top down”

(TD), provide empirical measurements of methane at

specific locations, rather than estimates based on emissions

factors. They use either ground-based instruments or those

on aircraft or satellites to estimate methane emissions. The

downsides of TD are its relative cost and coverage

limitations. At present, satellite- and aircraft-based

measurements cost more than the BU strategy described

above. Also, some TD methods (e.g., orbiting satellites)

typically occur at infrequent intervals and may miss

detection of sporadic emissions events. As remote detection

technologies mature, costs may drop. Increasing satellite

sampling frequency offers an opportunity to improve

accuracy and precision.

Satellite Measurement of Emissions

Remote measurement of methane using satellite-based

sensors typically detects the abundance of methane by

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Advances in Satellite Methane Emissions Measurement

measuring the methane-specific pattern of light absorption.

Since the launch of the Greenhouse Gases Observing

Satellite (GOSAT) by the Japanese government in 2009, the

number and capabilities of methane emissions observing

satellites has increased. Participants in satellite methane

emission observation now include the private sector and

nongovernmental organizations. The satellite platforms

described here are not operated directly by the U.S.

government, although U.S. researchers use the data.

Satellite detection methods can involve trade-offs between

geographic coverage and image resolution that may allow

some fugitive emissions to go undetected. These trade-offs

may be addressed as technical capabilities improve and

datasets from satellites with complementary capabilities are

combined. As satellites pass overhead, they scan a

continuous strip of the Earth’s surface known as a swath.

The swath width is the horizontal width of this strip.

Existing satellite technologies present a trade-off between

the swath width and the resolution of the image. For

instance, a satellite such as the European Space Agency

instrument TROPOMI has a swath width of 2,600

kilometers (km) and spatial resolution of 7 km x 3.5 km.

This relatively wide swath scans a large area but typically

lacks the resolution to distinguish individual surface

features, such as specific oil or gas facilities.

Other satellites, such as the Italian Space Agency

instrument PRISMA—with a swath width of 30 km and a

spatial resolution of 30 meters (m), with a high-resolution

sensor—may be able to distinguish such facilities. Such a

narrow swath width restricts the area that can be sampled

on any given overpass of a satellite. The trade-off between

these two types of satellites means that a wide-survey

satellite may detect an area of high emissions but lack the

resolution to attribute it to a specific facility, whereas a

high-resolution satellite may miss a sporadic emissions

event altogether if it is outside the narrower swath width.

Researchers have strategies to address these trade-offs and

improve the detection, quantification, and attribution of

fugitive methane emissions. These strategies include

increasing satellite survey capacity to detect elevated

regional methane concentrations in order to detect areas of

high emissions, increasing satellite capacity for direct

location attribution of such events, and using data from

satellites with complementary capabilities. One way of

increasing the capacity of satellites to detect methane

emissions is making available more high-resolution

satellites for observations. For example, 12 high-resolution

private-sector Canadian GHGSat satellites and the Tanager

-1 satellite (a Carbon Mapper project with an instrument

developed by NASA’s Jet Propulsion Laboratory) with

spatial resolution approximately 30 m x 30 m are currently

operational. These systems are generally able to discern

individual point sources of fugitive emissions at the facility

level, allowing specific attribution in some cases. These

satellites are capable of sampling areas of high emissions

that are identified by wide-area survey satellites such as the

European Space Agency TROPOMI instrument on board

the Copernicus Sentinel-5 Precursor satellite launched in

2017.

Recent scientific advances in hyperspectral sensing may

also increase the capacity for detecting emissions.

Hyperspectral instruments collect data on hundreds of

narrow bands across the electromagnetic spectrum.

Experiments have shown that hyperspectral sensors can be

used to measure atmospheric methane. Satellites such as

PRISMA (launched in 2019), Copernicus Hyperspectral

Imaging Mission for the Environment (CHIME; a European

Space Agency mission in collaboration with NASA), and

ZY-1 02D (a Chinese satellite launched in 2019) combine

this ability to measure methane with a spatial resolution

better than 50 m x 50 m. This is likely sufficient to allow

fugitive emissions attribution to a specific facility. Making

use of the data from these satellites for fugitive emissions

detection could add to current attribution capabilities.

The capacity to detect emissions may also be enhanced by

MethaneSAT, which has area coverage and resolution

capabilities between wide-area survey satellites such as

TROPOMI and high-resolution satellites such as Tanager-1.

MethaneSAT is a joint project of the Environmental

Defense Fund (a U.S. nonprofit) and the New Zealand

Space Agency. Its specifications include a swath width

greater than 200 km, a spatial resolution of 100 m x 400 m,

and a detection threshold of approximately 3 parts per

billion (ppb) of methane. MethaneSAT is able to survey

large areas and detect methane emissions with some spatial

specificity, although its ability to attribute an emissions

event to a specific facility is limited.

EPA’s Methane Super Emitter Program

EPA established the Methane Super Emitter Program as

part of the agency’s final 2024 rule for NSPS and EG for

the Crude Oil and Natural Gas source category. Under this

program, third parties apply for certification to submit data

to EPA using approved remote-sensing technology. If a

third party is certified, it may submit to EPA notifications

that contain specified information on methane releases. The

notification must be submitted within 15 calendar days of

the date the release event is detected. EPA reviews the

submission for accuracy and completeness and then notifies

the owner or operator of the source responsible for the

potential super-emitter event. According to the 2024 rule,

the responsible entity must then initiate an investigation of

the event within 5 days and report the findings to EPA

within 15 days. When an emissions event has been

identified, the owner or operator must report details about

that event. The required reporting details are dependent on

the source of the emissions, such as an oil or natural gas

facility. The super-emitter event investigation may include

various actions, such as reviewing maintenance activities,

reviewing monitoring data, reviewing the results of a

fugitive emissions survey, and screening the whole facility

with optical gas imaging. If the super-emitter event was

found to be from fugitive methane emissions, the owner or

operator must comply with the fugitive emissions

monitoring and repair requirements of the NSPS and EG for

the Crude Oil and Natural Gas source category.

Jonathan D. Haskett, Analyst in Environmental Policy

Omar M. Hammad, Analyst in Environmental Policy

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Advances in Satellite Methane Emissions Measurement

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