Table of Contents
Major Topic Sections
Related topics in this section
Reducing non-CO2 GHG
While carbon dioxide (CO2)
is the primary anthropogenic GHG emission, other GHGs are significant in
quantity. During 2007,
reports that in 2008, approximately 83 percent of total U.S. GHG emissions
consisted of CO2 from the combustion and nonfuel use of fossil
fuels. Other gases -
methane, nitrous oxide, HFCs, PFCs, and SF6
- amounted to more than 1.2 billion
tons of CO2-equivalent emissions in 2008. These other gases
particularly methane and SF6 -
offer many opportunities for reduction by the
electric power industry.
Methane (CH4) is a potent
greenhouse gas, having over 20 times the global warming potential (GWP) of
carbon dioxide. Methane is emitted from a variety of natural and
human-influenced sources. Human-influenced sources include landfills, natural
gas and petroleum systems, agricultural activities, coal mining, stationary
and mobile combustion, wastewater treatment, and certain industrial process.
Methane emissions account for
approximately ten percent of total U.S. anthropogenic GHG emissions, second
only to carbon dioxide. The five primary sources of methane emissions
landfills, livestock management, natural gas systems, coal mining, and
manure management -
together account for about 95 percent of U.S. methane emissions.
Sulfur hexafluoride (SF6) is a
highly potent greenhouse gas used in the power industry for insulation and
current interruption in electric transmission and distribution equipment.
The physical quantities that are emitted are small, fewer than 1,000 tons
per year. However, the GHG effect of these emissions is large, as the global
warming potential of SF6 is
more than 20,000 times greater than
CO2. Because of this
extremely high GWP, one pound of SF6 has the same global warming impact of
10-11 tons of CO2. The
U.S. emissions of SF6
is less than the equivalent of 20 million metric tons of CO2, less than one percent of total U.S. GHG
emissions. Most of this is from the electric power industry.
Unlike CO2, where most
emissions can be viewed as a co-product of combustion or calcination; most
sources of methane and SF6 emissions are incidental emissions, being
either accidental releases or related to variable biological or geological
processes. The emissions are generally dispersed and the processes will
often vary with site-specific conditions. In general, where emissions are a
co-product of a specific activity such as fossil fuel burning, measurements
can typically be made with a high degree of precision. Incidental emissions
such as most methane and SF6 sources are, in contrast, variably
related to an activity’s inputs, and are often spread out over time.
The management and use of methane and SF6
can significantly reduce the overall emission of greenhouse gases. Studies
by U.S. EPA indicate that there are many actions that can be taken to reduce
these emissions at little or no cost. There are a variety of ways that
utilities can participate – either directly or indirectly – in reducing
emissions of these greenhouse gases, including:
Landfill Methane Energy Recovery
Reducing Emissions of Natural Gas
Coal Mine Methane Recovery
Animal Waste Methane Energy Recovery
Emission Reduction Partnership for Electric Power Systems
The Resource Guide pages to the left, identified as "Related topics in this
section", discuss each of these methane and SF6
reduction activities in turn. The resources identified below are more
applicable to methane management in general.
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comments to the PPRG.
Note: Most Power Partners℠ projects within this section
will likely be listed under one of the specific topics. Projects described
below are those that relate to the section contents more broadly.
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Resources and links specific to
individual topics within this section are listed separately for that topic’s
web page. The Resource links shown below are more cross-cutting, and relate
to non-CO2 greenhouse
gases in general. Additional resources are provided for the specific topic
areas indicated by the link bar on the left of this page.
Environmental Protection Agency, “Methane”
Many companies in the U.S.
are working with EPA in various efforts to reduce emissions by
implementing cost-effective management methods and technologies. This Home
Page provides links to more information on methane and EPA's related
activities, including science, emissions, mitigation costs, and programs for
Agency, “Methane to Markets Partnership”
The international Methane to
Markets Partnership, launched in November 2004, committed the United States
and 13 other countries to advancing cost-effective, near-term methane
recovery and use as a clean energy source. The Partnership focuses on
methane recovery and use opportunities in the agriculture (animal waste
management), coal mine, landfill, and oil and gas system sectors. Since its
launch, the Partnership has added multiple Partner Governments and private
and non-government participants who work collaboratively to implement
projects around the globe. Public and private sector organizations around
the world are now working together with government agencies to facilitate
methane reduction projects in agriculture, coal mines, landfills and oil and
gas systems. This collaboration is yielding important benefits, including
enhanced economic growth and energy security, improved air quality and
industrial safety, and reduced greenhouse gas (GHG) emissions.
Agency, “Opportunities to Reduce Anthropogenic Methane Emissions in the
United States. 1993 Report to Congress," EPA 430-R-93-0012
A Table of Contents and Order
Form are presented; only hard copies are available. Reports will be sent via U.S. Mail. Alternatively,
reports can be ordered by phone at 1-800-STAR-YES.
Agency, "Report on U.S. Methane Emissions 1990-2020: Inventories,
Projections, and Opportunities for Reductions," EPA 430-R-99-013, September
This report addresses the historical emissions of CH4
and presents EPA's forecast of emissions through 2020 for landfills, natural
gas and oil systems, coal mines, manure management and enteric fermentation.
The report also estimates the costs of reducing CH4 emissions
from landfills, natural gas systems, coal mines and manure management.
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