Updated March 16, 2022
Methane Emissions: A Primer
Methane: The Chemical
can affect human health and safety and the environment.
Methane is the world’s simplest hydrocarbon, with a
The U.S. Occupational Safety and Health Administration
chemical formula of CH4 (one atom of carbon and four
lists methane as both an asphyxiant and an explosive;
atoms of hydrogen). It is gaseous under normal atmospheric
increased concentrations in local settings can jeopardize
conditions and is commonly produced through the
worker safety. Further, the U.S. Environmental Protection
decomposition of organic materials in the absence of
Agency (EPA) classifies methane as both a precursor to
oxygen. It is released into the atmosphere by natural
ground-level ozone formation (commonly referred to as
sources such as wetlands, oceans, sediments, termites,
“smog”) and a potent GHG, albeit with a shorter
volcanoes, and wildfires as well as human activities such as
atmospheric life than CO2. Methane’s effect on climate
oil and natural gas systems, coal mines, landfills,
change is up to 34 times greater than that of CO2 when
wastewater treatment facilities, and the raising of livestock.
averaged over a 100-year time period, and even greater
when considered over the first 20 years after it is emitted.
Methane: The Fuel and Feedstock
Arguably, any increase in methane emissions may
Methane is the primary component of natural gas. When
counteract some of the environmental benefits that the U.S.
extracted from geologic formations or captured by other
economy has to gain by switching from coal or oil to
means, it can be used as either a fuel or as a chemical
natural gas. For these reasons, some state governments and
feedstock for industry.
the Obama Administration promulgated regulations to limit
methane emissions in certain industrial sectors. The Trump
When used as a fuel, methane has many advantages over
Administration, in line with executive orders to promote
other hydrocarbons (e.g., coal and oil). Methane is more
energy independence and economic growth, revised or
versatile: It can heat homes, fuel stoves, run vehicles, fire
rescinded many of those federal regulations. The Biden
power plants, and be exported, either as a gas or liquefied,
Administration has sought to reengage federal efforts to
to support the energy needs of U.S. trading partners.
address methane emissions.
Methane is cleaner-burning: It emits, on average, about half
as much carbon dioxide (CO2) as coal and one-quarter less
Typically, air pollution regulations compete against the
than oil, per unit of energy, when consumed in a typical
economic considerations of affected industries. In
electric utility plant. Further, its combustion emits no
methane’s case, however, its dual nature as a commodity
mercury (a persistent, bio-accumulative neurotoxin),
and a pollutant can provide a unique set of incentives.
virtually no particulate matter or sulfur dioxide (SO2), and
Under certain conditions, the market value of fugitive
less nitrogen oxides, per unit of energy, than either coal or
methane and other byproduct emissions that can be avoided
oil. Recent expansion of natural gas production—primarily
or recovered may be able to offset some of the cost of
as a result of improved technologies (e.g., hydraulic
controls. Further, the value of these avoided or recovered
fracturing and directional drilling) used on unconventional
emissions during oil and gas extraction can contribute to
resources (e.g., shale, tight sands, and coalbed methane)—
increased royalty payments to state and federal
has made methane a major component in the energy supply
governments.
and security of the United States.
Methane emissions are not always easy to find and capture.
When used as a chemical feedstock, methane is a
Methane, unlike some other pollutants (e.g., SO2 or CO2), is
manufacturing component for a wide variety of household
not commonly emitted in a concentrated stream from
and industrial products including plastic, fertilizer,
industrial processes. Rather, it is released into the
antifreeze, and fabrics. Abundant and economical supplies
atmosphere through dispersion, leaks, vents, accidents, and
of methane support the U.S. petrochemical sector, aiding in
ruptures. In this way, methane emissions are most similar to
the creation of domestic jobs and economic development.
those of other volatile organic compounds, both in manner
and control. Efforts to monitor, capture, or abate these
For these reasons, many have advocated for the increased
emissions are generally more difficult or costly than for
production and use of methane (via natural gas extraction or
other pollutants. Whether the prevention of fugitive
other capture technologies) and have hailed it as a potential
methane emissions or their recovery is profitable for
“cost-effective bridge” to a less polluting and lower
producers may depend upon a number of factors, including
greenhouse gas (GHG)-intensive economy. Many Members
the nature and extent of the release, the control technology
of Congress and recent Administrations have supported this
available, and the market price for the avoided or recovered
position.
products. In this way, the cost-benefit consideration of
methane capture becomes similar to that of energy-
Methane: The Pollutant
efficiency efforts, wherein higher up-front investments and
Methane, however, when vented or leaked into the
other market barriers have the potential to be offset over
atmosphere (commonly referred to as “fugitive” emissions),
time.
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Methane Emissions: A Primer
Methane Emissions
Issues for Congress
According to EPA, methane is the second-most-prevalent
Through the years, the federal government has sought
GHG emitted in the United States (behind CO2), and in
policies (legislative and regulatory) to control methane
2019 it accounted for 660 million metric tons of CO2
emissions while balancing several goals, including
equivalent, or approximately 10% of all domestically
promoting domestic energy production and security,
produced GHG emissions from human activities. Some
protecting the property rights of mineral owners
academic and other government studies put these emissions
(including federal resource rights and royalties),
higher. Of the total methane emissions in 2019, 40% were
assuring the operational safety of employees who work
emitted from sources in the energy and industrial sector,
with or near significant emission sources, and
40% from sources in the agricultural sector, and 20% from
safeguarding the general population from the impacts of
sources in the waste sector. Between 1990 and 2019, EPA
air pollution and GHG emissions.
data indicate U.S. methane emissions decreased by 15%.
Still, trends have fluctuated over the past decade, with
Some stakeholders raise concerns over federal controls.
increases reported in some years, including 2017-2019.
They argue that more stringent standards on emissions
Since 1990, emissions from sources associated with
would not provide cost-effective health and environmental
agriculture have increased, while emissions from sources
benefits. Some industries contend that they are already
associated with waste management, energy, and industrial
doing everything feasible to prevent, capture, and reuse
processes have decreased (Figure 1). (CRS chose to
methane emissions (for economic and safety reasons).
analyze EPA’s data for 2019 instead of its data for 2020
Others note that state and local authorities are better
due to the atypical effects of the Coronavirus Disease 2019
equipped to oversee and enforce emission reduction efforts.
[COVID-19] pandemic on emissions.)
Federal Actions
Economic and technical issues pose challenges to making a
On November 2, 2021, the Biden Administration released
comprehensive national inventory of methane emissions.
the “U.S. Methane Emissions Reduction Action Plan,” a set
Unlike CO2, whose emissions are reported using well-
of policies to increase efforts across the federal government
tracked energy statistics, methane is emitted to the
to reduce methane emissions. These include the following:
atmosphere primarily through fugitive releases. Thus, it is
challenging to acquire comprehensive and consistent
EPA-proposed performance standards for methane
observational data. For this reason, methodologies for
emissions from new oil and natural gas sources and
quantifying methane emissions are under near-constant
first-time emissions guidelines for states on existing oil
revision and debate. Concurrently, new techniques and
and natural gas sources (86 Federal Register 63110).
technologies to measure and report emissions (e.g., from
EPA initiatives to reduce methane emissions at
aircraft and satellites) continue to be developed.
municipal solid waste landfills through (1) a program to
reduce food loss and waste and (2) a voluntary outreach
Figure 1. U.S. Methane Emissions: Historical Trends
program for emissions capture. These initiatives would
complement existing performance standards (81 Federal
Register 59332) and emissions guidelines for states (81
Federal Register 59276) from 2016.
Department of the Interior-proposed standards for waste
prevention during the venting and flaring of methane
from oil and natural gas operations and well closures on
public lands and waters.
Pipeline and Hazardous Materials Safety Administration
(PHMSA) rules, pursuant to the implementation of the
PIPES Acts of 2016 and 2020 (P.L. 114-183 and P.L.
116-260, Division R), that would, among other things,
require operators to address methane leaks.
Department of Agriculture programs that include (1) a
voluntary, incentive-based “climate-smart” agriculture
program to reward farmers and ranchers for methane
reductions; (2) a climate-smart partnership initiative
targeting commodities’ supply chains; and (3) a public-
private partnership to promote biogas programs.
Further, on November 5, 2021, Congress enacted the
Infrastructure Investment and Jobs Act (P.L. 117-58) that
authorized, among other items, $4.7 billion for programs to
plug, remediate, and reclaim abandoned oil and natural gas
wells, and $1.0 billion for a new grant program at PHMSA
aimed at reducing methane leaks from antiquated pipes.
Source: CRS, with data from the U.S. Environmental Protection
Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-
Richard K. Lattanzio, Specialist in Environmental Policy
2019, 430-R-21-005, April 14, 2021, Table 2.1.
IF10752
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Methane Emissions: A Primer
Disclaimer
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