Updated December 11, 2020
Methane Emissions: A Primer
Methane: The Chemical
Methane: Pollutant
Methane is the world’s simplest hydrocarbon, with a
Methane, however, when released or allowed to escape into
chemical formula CH4 (one atom of carbon and four atoms
the atmosphere (commonly referred to as “vented” and
of hydrogen). It is gaseous under normal atmospheric
“fugitive” emissions, respectively), can affect human health
conditions and is commonly produced through the
and safety and the environment. The U.S. Occupational
decomposition of organic materials in the absence of
Safety and Health Administration lists methane as both an
oxygen. It is released into the atmosphere by natural
asphyxiant and an explosive, as increased concentrations in
sources such as wetlands, oceans, sediments, termites,
local settings can jeopardize worker safety. Further, the
volcanoes, and wildfires as well as human activities such as
U.S. Environmental Protection Agency (EPA) classifies
oil and natural gas systems, coal mines, landfills,
methane as both a precursor to ground-level ozone
wastewater treatment facilities, and the raising of livestock.
formation (commonly referred to as “smog”) and a potent
greenhouse gas (GHG), albeit with a shorter atmospheric
Methane: Fuel and Chemical Feedstock
life than CO2. Methane’s effect on climate change is up to
Methane is the primary component of natural gas. When
34 times greater than that of CO2 when averaged over a
extracted from geologic formations or captured by other
100-year time period and even greater when considered
means, it can be used as either a fuel or as a feedstock for
over the first 20 years after it is emitted. Arguably, any
the chemical industry.
increase in methane emissions may counteract some of the
environmental benefits that the U.S. economy has to gain
When used as a fuel, methane has many advantages over
by switching from coal or oil to natural gas. For these
other hydrocarbons (e.g., coal and oil). Methane is more
reasons, some state governments and the Barack Obama
versatile: It can heat homes, fuel stoves, run vehicles, fire
Administration promulgated regulations to control for
power plants, and be exported, either as a gas or liquefied,
methane emissions in certain industrial sectors. The Donald
to support the energy needs of U.S. trading partners.
Trump Administration, in line with executive orders to
Methane is cleaner-burning: It emits, on average, about half
promote energy independence and economic growth,
as much carbon dioxide (CO2) as coal and one-quarter less
revised or rescinded many of the federal regulations.
than oil, per unit of energy, when consumed in a typical
electric utility plant. Further, its combustion emits no
Generally, air pollution regulations compete against the
mercury (a persistent, bio-accumulative neurotoxin),
economic considerations of affected industries. In
virtually no particulate matter or sulfur dioxide (SO2), and
methane’s case, however, its dual nature as both a
less nitrogen oxides, per unit of energy, than either coal or
commodity and a pollutant can provide a unique set of
oil. Recent expansion of natural gas production—primarily
incentives. Under certain conditions, the value of fugitive
as a result of improved technologies (e.g., hydraulic
methane and other byproducts that can be recovered and
fracturing and directional drilling) used on unconventional
sold at market may be able to offset some of the cost of
resources (e.g., shale, tight sands, and coalbed methane)—
their capture. Further, the value of these recovered products
has made methane an increasingly significant component in
during oil and gas extraction can contribute to increased
the energy supply and security of the United States.
royalty payments to state and federal governments.
When used as a chemical feedstock, methane is a
The difficulty, however, is that methane emissions are not
manufacturing component for a wide variety of household
always easy to find and capture. Methane, unlike some
and industrial products including plastic, fertilizer,
other pollutants (e.g., SO2 or CO2), is not commonly
antifreeze, and fabrics. Abundant and economical supplies
emitted in a concentrated stream from industrial processes.
of methane may arguably serve to reinvigorate the U.S.
Rather, it is released into the atmosphere through
petrochemical sector, bringing manufacturing industries
dispersion, leaks, vents, accidents, and ruptures. In this
back on shore and aiding in the creation of domestic jobs
way, methane emissions are most similar to those of other
and economic development.
volatile organic compounds, both in manner and control.
Efforts to monitor, capture, or abate these emissions are
For these reasons, many have advocated for the increased
generally more difficult and costly than for other pollutants.
production and use of methane (via natural gas extraction or
Whether recovery of methane is profitable for producers
other capture technologies) and have hailed it as a potential
may depend upon a number of factors, including the nature
“cost-effective bridge” to a less polluting and lower
and extent of the release, the technology available for
greenhouse gas-intensive economy. Many Members of
capture, and the market price for the recovered products. In
Congress and recent Administrations have supported this
this way, the cost-benefit consideration of methane capture
position.
becomes similar to that of energy efficiency efforts,
wherein higher up-front investments and other market
barriers have the potential to be offset over 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
2018—the latest year of available data—it accounted for
emissions for a variety of economic, environmental, public
634 million metric tons of CO2 equivalent, or almost 10%
health, and safety reasons, including
of all domestically produced GHG emissions from human
promoting domestic energy production and security,
activities. Some studies have put these emissions higher. Of
protecting the property rights of mineral owners
the total, 40% was emitted from sources in the energy and
(including federal resources and associated royalties to
industrial sector, 40% from sources in the agricultural
the American taxpayer),
sector, and 20% from sources in the waste sector.
assuring the operational safety of employees who work
with or near significant emission sources, and
Between 1990 and 2018, EPA data indicate U.S. methane
safeguarding the general population from air pollution.
emissions decreased by 18%. Still, trends have fluctuated
over the past decade, with increases reported in some years.
Some stakeholders raise concerns over federal controls.
Since 1990, emissions from sources associated with
They argue that more stringent standards on methane
agriculture have increased, while emissions from sources
emissions would not provide cost-effective health and
associated with waste management, energy, and industrial
environmental benefits. Some industries contend that they
processes have decreased (see Figure 1).
are already doing everything feasible to capture and reuse
methane emissions (for economic and safety reasons).
Economic and technical difficulties have made a
Others note that state and local authorities are better
comprehensive national inventory of methane emissions
equipped to oversee and enforce emission reduction efforts.
difficult to attain. Unlike CO2, whose emissions are
reported using well-tracked energy statistics, methane is
Under President Obama, federal activities in support of
emitted to the atmosphere primarily through fugitive
methane emission reductions became a cornerstone of his
releases. Thus, one of the greater difficulties in
“Climate Action Plan,” and the Administration promulgated
understanding the effects of methane emissions on human
several regulations to address emissions, including:
health and the environment is acquiring comprehensive and
consistent observational data. For this reason,
EPA standards to reduce methane emissions from new
methodologies for quantifying methane emissions are under
and modified activities and equipment in the oil and
near-constant revision. Concurrently, new techniques and
natural gas sector (finalized on June 3, 2016).
technologies to measure and report emissions (e.g., on
EPA standards to reduce methane emissions from new
aircraft and satellite) continue to be developed.
and existing municipal solid waste landfills (finalized on
August 29, 2016).
Figure 1. U.S. Methane Emissions: Historical Trends
Bureau of Land Management (BLM) standards to
prevent the waste of gas (i.e., methane) through venting
and flaring during oil and natural gas production on
public lands (finalized on November 18, 2016).
President Trump subsequently signed Executive Order
13783 on March 28, 2017, requiring agencies to review
existing regulations and “appropriately suspend, revise, or
rescind those that unduly burden” domestic energy
production and use. Further, the federal courts have
reviewed provisions in the Obama-era standards and the
Trump Administration’s revisions. As a result, the status of
federal methane regulation is as follows:
EPA rescinded the 2016 methane standards for the oil
and gas sector (September 14, 2020).
EPA announced it would reconsider certain aspects of
the 2016 methane standards for the landfill sector (May
5, 2017). In August 2019, EPA finalized two actions
related to the standards’ timing and implementation.
BLM rescinded the 2016 waste prevention standards for
the oil and gas sector (September 28, 2018). A
California federal district court vacated the rescission
(July 15, 2020). However, a Wyoming federal district
court subsequently vacated all provisions in the 2016
rule related to the loss of gas (October 8, 2020).
Source: CRS, with data from the U.S. Environmental Protection
Richard K. Lattanzio, Specialist in Environmental Policy
Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-
2018, 430-R-20-002, April 13, 2020, Table 2.1.
IF10752
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Methane Emissions: A Primer
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