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Landfill Methane Outreach Program (LMOP)

Renewable Natural Gas

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Basic Information about RNG

Renewable natural gas (RNG)* is a term used to describe biogasHelpbiogasGas resulting from the decomposition of organic matter under anaerobic conditions. The principal constituents are methane and carbon dioxide. that has been upgraded for use in place of fossil natural gas. The biogas used to produce RNG comes from a variety of sources, including municipal solid waste landfills, digesters at water resource recovery facilities (wastewater treatment plants), livestock farms, food production facilities and organic waste management operations.

As a substitute for natural gas, RNG has many end uses:

  • in thermal applications,
  • to generate electricity,
  • for vehicle fuel or
  • as a bio-product feedstock.

RNG can be used locally at the site where the gas is created or it can be injected into natural gas transmission or distribution pipelines.

Raw biogas has a methane content between 45 and 65 percent, depending on the source of the feedstock, and must go through a series of steps to be converted into RNG. Treatment includes removing moisture, carbon dioxide (CO2) and trace level contaminants (including siloxanes, volatile organic compounds, or VOCs, and hydrogen sulfide), as well as reducing the nitrogen and oxygen content. Once upgraded, the gas has a methane content of 90 percent or greater. Typically, RNG injected into a natural gas pipeline has a methane content between 96 and 98 percent.

*RNG is a “term of art” and there is not at present a standard definition. This description has been developed by EPA’s voluntary programs.

Diagrams of RNG Sources, Gas Treatment and End Uses

Click on a thumbnail image to see the full-sized diagram.


RNG Project Map

Biogas from a variety of sources is being upgraded into RNG across the United States. This map shows operational RNG projects in the United States where the biogas is generated from landfills or livestock waste anaerobic digesters.

Sources of these data include:

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Benefits

Use of RNG can provide benefits in terms of fuel security, economic revenues or savings, local air quality and greenhouse gas emission reductions.

Fuel diversity benefits

Use of RNG increases and diversifies domestic energy production. RNG can be used as a baseload fuel source with high availability rates. It leverages existing infrastructure such as pipelines and heavy-duty vehicles. Biogas feedstocks for RNG are generated continuously from a variety of sources.

Economic benefits

The development of RNG projects can benefit the local economy through the construction of RNG processing and fueling station infrastructure and sale of natural gas powered vehicles. National, state and local incentives may be available depending on the end use, such as credits for production of RNG used for vehicle fuel. These financial incentives can provide additional economic drivers for project development.

Local air quality benefits

Replacing traditional diesel or gasoline with RNG can significantly reduce emissions of nitrogen oxides and particulate matter, resulting in local air quality benefits. RNG is comprised primarily of methane; compared to fossil natural gas, RNG contains zero to very low levels of constituents, such as ethane, propane, butane, pentane or other trace hydrocarbons.

Greenhouse gas emission reductions

RNG projects capture and recover methane produced at a landfill or anaerobic digestion facility. Methane has a global warming potential more than 25 times greater than CO2 and a relatively short (12-year) atmospheric life, so reducing these emissions can achieve near-term beneficial impacts in mitigating global climate change. For facilities that are not already required to mitigate such emissions, an RNG project can reduce methane emissions significantly.

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Resources

The following EPA resources are available to learn more about RNG:

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More Information on RNG

The following EPA programs work cooperatively with industry stakeholders to reduce or avoid methane emissions by supporting biogas energy projects including those that produce RNG.

Landfill Methane Outreach Program Logo - Image of a green earth above a blue flameEPA’s Landfill Methane Outreach Program (LMOP) encourages the recovery and beneficial use of biogas generated from organic municipal solid waste. LMOP maintains a database that includes operational RNG projects as well as opportunities for landfill sites where RNG could potentially be generated. In addition, LMOP publishes tools and resources to support the development of RNG projects.

AgSTAREPA’s AgSTAR promotes the use of biogas recovery systems to reduce methane emissions from livestock waste. AgSTAR provides a wide variety of resources and tools for stakeholders interested in exploring the use of anaerobic digester systems and maintains a list of projects with information on the AD feedstock sources and end use of the biogas.

Natural Gas STAREPA’s Natural Gas STAR programs encourage oil and natural gas companies to adopt cost-effective technologies and processes that improve operational efficiencies and reduce methane emissions. The program also facilitates technology transfer between stakeholders to discuss technical questions regarding the injection of RNG into the natural gas pipeline network.

Green Power PartnershipEPA’s Green Power Partnership is a voluntary program that encourages organizations to use green power as a way to reduce the environmental impacts associated with conventional electricity use.

The Renewable Fuel Standard Program (RFS) is run by the EPA Office of Transportation and Air Quality. Learn more about the RFS.

This diagram shows the waste types that can be used to create renewable natural gas and how these waste types are either deposited in landfills or anaerobic digesters. Waste types of municipal solid waste, sewage sludge, yard and crop wastes, and food and food processing wastes can be deposited into municipal solid waste landfills. Waste types of sewage sludge, yard and crop wastes, food and food processing wastes, and manure can be deposited into anaerobic digesters. Both landfills and anaerobic digesters create biogas. Biogas made from organic sources through anaerobic processes contains 45 to 65 percent methane. Biogas is treated to remove moisture, particulates, contaminants and other gases (including carbon dioxide, oxygen, nitrogen, and volatile organic compounds); this increases the methane content to 90 percent or greater, typically 96 to 98 percent methane for pipeline injection. The resulting product is renewable natural gas.
This diagram shows the basic components of varying stages of treatment for landfill gas to be used as a biogas. Primary treatment of landfill gas for moisture and particulate removal includes a knockout pot, filter and blower. The gas then goes to a flare for combustion or to a secondary treatment stage. Secondary treatment of landfill gas for contaminant removal and compression includes moisture removal, siloxane/sulfur removal and a compressor, resulting in biogas. The biogas has various end uses in three main categories: heating, electricity and other industrial uses, or the biogas can be treated further in an advanced treatment stage. Advanced treatment for upgrading the biogas to pipeline quality gas or vehicle fuel includes removal of carbon dioxide, oxygen, nitrogen and volatile organic compounds, a flare/thermal oxidizer for waste/tail gas, and a compressor. The resulting product is renewable natural gas.
This diagram shows the basic products from anaerobic digestion and the basic components of treatment for anaerobic digester gas to be used as a biogas. The digested material that is liquid can be used as fertilizer. The digested material that is solid can be used as a soil amendment, for animal bedding or for other innovative uses. The anaerobic digester gas has moisture removed for combustion in a flare or the gas can have moisture removal plus siloxane/sulfur removal and then be compressed for use as a biogas. The biogas has various end uses in three main categories: heating, electricity and other industrial uses, or can be treated further. The biogas can be further treated for carbon dioxide removal and additional compression, resulting in renewable natural gas.
This diagram shows the basic delivery methods of renewable natural gas as either Local Use or Pipeline Injection; and shows the basic end uses of renewable natural gas as Vehicle Fuel, for Electricity or in Thermal Applications.

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