Frequent Questions about Landfill Gas

LMOP provides responses to some common questions that can help increase your understanding of the program, landfill gas (LFG), LFG energy projects and the LMOP Landfill and Landfill Gas Energy Project Database. The questions and answers are organized into four categories below. For information from EPA on broader topics, see Methane or Climate Change.

LMOP

Landfill Gas

LFG Energy Projects

LMOP Database

LMOP

What is LMOP?

LMOP is a voluntary program that works cooperatively with industry stakeholders and waste officials to reduce or avoid methane emissions from landfills. LMOP encourages the recovery and beneficial use of biogas generated from organic municipal solid waste (MSW). LMOP forms partnerships with communities, landfill owners and operators, utilities, power marketers, states, project developers, tribes and nonprofit organizations to overcome barriers to project development.

Why is LMOP promoting the use of landfill gas?

MSW landfills are the third-largest source of methane emissions in the United States generated by human activity, accounting for approximately 14.4 percent of these emissions in 2022. At the same time, methane emissions from landfills represent a lost opportunity to capture and use a significant energy resource. Using LFG is a win/win opportunity. LFG energy projects involve citizens in sustainable community planning and create partnerships. By linking communities with innovative ways to deal with their LFG, LMOP contributes to the creation of livable communities that enjoy increased environmental protection, better waste management, and responsible community planning.

Who participates in LMOP?

LMOP participants include LMOP Industry Partners, such as LFG energy project developers, equipment suppliers, and financiers; LMOP State Partners, who provide permitting, incentive program, and regulatory guidance; LMOP Energy Partners, who include energy service providers and direct end users of LFG; LMOP Community Partners, who include communities and landfill owner/operators; and LMOP Endorsers, nonprofit organizations coordinating with EPA to promote LFG among their members or constituents.

What are LMOP’s activities?

LMOP activities include:

  • Providing technical assistance, guidance materials and software to assess the potential economic feasibility of an LFG energy project.
  • Developing informational materials about the benefits of renewable energy from biogas generated from MSW, as well as opportunities to reduce emissions from existing MSW landfills.
  • Fostering partnerships and identifying financing for biogas projects.
  • Creating networking opportunities with peers and renewable energy experts.

Does EPA regulate landfill gas?

Existing regulations under the Clean Air Act require landfills of a certain size to install and operate a gas collection and control system. These regulations target MSW landfill emissions (commonly referred to as LFG). The regulations require non-methane organic compounds (NMOCs) to be measured as a surrogate for LFG and owner/operators to collect and combust their LFG. Landfill owner/operators can either flare the LFG, use the LFG as a renewable energy resource, or treat the LFG for subsequent sale.

Which landfills are required to report greenhouse gas emissions data to EPA?

MSW landfills and industrial landfills are required to report data under EPA’s Greenhouse Gas Reporting Program (GHGRP) if annual methane generation is greater than or equal to 25,000 metric tons of carbon dioxide equivalent (MTCO2e). Landfills that meet the threshold must report methane generation, methane emissions and associated data. MSW landfills report under subpart HH and industrial landfills report under subpart TT.

Landfills that are LMOP Partners may provide data during annual LMOP Partner Reporting related to landfill characteristics such as size, operational status and location as well as LFG energy project parameters including technology type, amount of LFG used and start date. LMOP Partners do not report landfill emissions data to LMOP but rather provide key details about landfills and projects.

Where can I get additional information about regulations for municipal solid waste landfills?

For information about regulations that affect landfills or LFG energy projects, see LMOP’s Quick Reference Sheet.

Landfill Gas

How is landfill gas generated?

LFG is generated during the natural process of bacterial decomposition of organic material contained in MSW landfills. A number of factors influence the quantity of gas that a MSW landfill generates and the components of that gas. These factors include, but are not limited to, the types and age of the waste buried in the landfill, the quantity and types of organic compounds in the waste, and the moisture content and temperature of the waste. Temperature and moisture levels are influenced by the surrounding climate.

Learn more about LFG in Chapter 1 of LMOP's LFG Energy Project Development Handbook.

What components make up landfill gas?

By volume, LFG is about 50 percent methane and 50 percent carbon dioxide and water vapor. It also contains small amounts of nitrogen, oxygen, and hydrogen, less than 1 percent non-methane organic compounds (NMOCs), and trace amounts of inorganic compounds. Some of these compounds have strong, pungent odors (for example, hydrogen sulfide). NMOCs consist of certain hazardous air pollutants (HAPs) and volatile organic compounds (VOCs), which can react with sunlight to form ground-level ozone (smog) if uncontrolled. Nearly 30 organic hazardous air pollutants have been identified in uncontrolled LFG, including benzene, toluene, ethyl benzene, and vinyl chloride. Exposure to these pollutants can lead to adverse health effects.

How are non-methane organic compounds generated in landfill gas?

NMOCs are contained in discarded items such as household cleaning products, materials coated with or containing paints and adhesives, and other items. During the waste decomposition process, NMOCs can be stripped from the waste by methane, carbon dioxide, and other gases and carried in LFG. Three different mechanisms are responsible for the production of NMOCs and their movement into LFG: (1) vaporization (the change of state from liquid or solid to vapor) of organic compounds until the equilibrium vapor concentration is reached, (2) chemical reaction of materials present in the landfill, and (3) biological decomposition of heavier organic compounds into lighter, more volatile constituents.

How much methane do U.S. landfills emit each year?

The Inventory of U.S. Greenhouse Gas Emissions and Sinks is updated annually. Per the most recent Inventory Report, U.S. landfills released an estimated 119.8 million metric tons of carbon dioxide equivalent (MMTCO2e) of methane into the atmosphere in 2022; this represents 17.1 percent of the total U.S. anthropogenic methane emissions across all sectors. MSW landfills contributed 100.9 MMTCO2e (14.4 percent of total U.S. methane emissions) while industrial landfills contributed the remaining 18.9 MMTCO2e (2.7 percent of total).

Where can I get additional information about the types and amounts of compounds found in landfill gas?

Final Emissions Factors for AP-42 Chapter 2, Section 4 - Municipal Solid Waste Landfills. U.S. EPA, Office of Air Quality Planning & Standards. August 2024.

The above webpage provides information about the current MSW landfill emission factors and how these changed from the previous factors. Both the chapter file (pdf) and spreadsheet (xlsx) provide typical concentrations for individual compounds from uncontrolled LFG in Tables 2.4-1 and 2.4-2 (the default concentrations are based on test data from multiple landfill sites), control efficiencies for several combustion devices in Table 2.4-3, and emission factors for secondary compounds exiting control devices in Tables 2.4-4 and 2.4-5.

LFG Energy Projects

Can landfill gas be used for energy?

LFG can be an asset when it is used as a source of energy to create electricity or heat. It is classified as a medium-Btu gas with a heating value of 350 to 600 British thermal units (Btu) per cubic foot, approximately half that of natural gas. LFG can often be used in place of conventional fossil fuels in certain applications. It is a reliable source of energy because it is generated 24 hours a day, 7 days a week. By using LFG to produce energy, landfills can significantly reduce their emissions of methane and avoid the need to generate energy from fossil fuels, thus reducing emissions of carbon dioxide, sulfur dioxide, nitrogen oxides, and other pollutants from fossil fuel combustion.

What are the economic benefits of using landfill gas as a resource?

LFG energy projects are a win-win opportunity for all parties involved, whether they are the landfill owner/operators, the local utility, the local government, or the surrounding community. Even before LFG energy projects produce profits from the sale or use of electricity, they produce a related benefit for communities: jobs. LFG energy projects involve engineers, construction firms, equipment vendors, and utilities or end users of the power produced. Much of this cost is spent locally for drilling, piping, construction, and operational personnel, providing additional economic benefits to the community through increased employment and local sales. Once the LFG system is in place, the captured gas can be sold for use as heat or fuel or be converted and sold on the energy market as renewable "green" power. In so doing, the community can turn a financial liability into an asset.

Learn more about the benefits of LFG energy in Chapter 1 of LMOP's LFG Energy Project Development Handbook.

What are the environmental benefits of using landfill gas as an energy resource?

Converting LFG to energy offsets the need for non-renewable resources such as coal and oil, and reduces emissions of air pollutants that contribute to local smog and acid rain. In addition, LFG energy projects help curtail global climate change, because they reduce emissions of methane, a greenhouse gas more potent than CO2. Combusting the LFG also destroys organic compounds, including methane and non-methane organic compounds (NMOCs). During combustion, these organic compounds chemically react with oxygen in the presence of heat, breaking apart to form water vapor, carbon dioxide, and other less volatile compounds. LFG energy projects go hand-in-hand with community commitments to cleaner air and reductions in greenhouse gases that cause global climate change.

Learn more about the benefits of LFG energy in Chapter 1 of LMOP's LFG Energy Project Development Handbook.

Who uses recovered landfill gas?

Almost any entity with energy needs can use LFG for a variety of purposes. One option is for utilities and power providers to purchase the electricity generated from the recovered LFG. Purchasing electricity from LFG enables utilities and power providers to add a renewable energy component to their energy portfolios. In addition, any entity (including municipalities, local industrial customers, and other organizations) that has a need for a direct and constant power supply is a good candidate for LFG use. LFG can be piped directly to a nearby facility for use as either a boiler or industrial process fuel. LFG can also be purified and injected into a natural gas distribution network or converted into renewable compressed or liquefied natural gas for vehicle fuels.

Learn more about LFG energy project types in Chapter 3 of LMOP's LFG Energy Project Development Handbook.

Are landfill owner/operators required to develop and implement LFG energy projects?

Existing regulations under the Clean Air Act require landfills of a certain size to install and operate a gas collection and control system. Landfills are not required to develop LFG energy projects, however under the regulations landfill owner/operators may control LFG by combusting it in an enclosed combustion device (such as a boiler, engine or turbine) for energy generation, by using a treatment system that processes the collected LFG for sale or beneficial use, or by flaring it. Beneficial use of LFG offers communities and landfill owner/operators the opportunity to reduce the costs associated with regulatory compliance by turning this landfill byproduct into a marketable resource.

For LFG electricity project owners whose project may be coming to an end, LMOP offers information in its Toolkit for Expiring LFG Electricity Power Purchase Agreements to help the landfill consider options to continue managing methane emissions.

Do LFG energy projects conflict with waste diversion?

The promotion of LFG energy is not in conflict with promotion of waste diversion and does not compete with waste reduction, recycling, and composting. LFG energy projects use methane that is generated from waste that has not been successfully diverted from landfills. The goal of LFG energy projects is to promote beneficial utilization of LFG collected from MSW landfills that have already disposed waste. It is possible to support the diversion of the organic fraction of discards from landfills so that uncontrolled methane is not generated and also support LFG energy projects that utilize methane generated from organic waste already disposed in landfills. The two positions are not in conflict.

Do LFG energy projects reduce greenhouse gas emissions?

The decomposition of organic waste generates methane, a greenhouse gas and a primary component of LFG. LFG energy projects reduce the amount of methane emitted from landfills as the LFG is captured and beneficially used in various types of technologies.

Landfills also have other options for reducing methane emissions even when an LFG energy project comes to an end. Read more in LMOP’s Toolkit for Expiring LFG Electricity Power Purchase Agreements.

Are there financial incentives for LFG energy projects?

A key component to successful LFG energy projects is identifying and using available financial mechanisms to promote the development of LFG resources. Funding resources may include grants, loans, tax credits and exemptions, and production incentives. It is important that stakeholders understand the range of available financial mechanisms to select the best options to meet project goals.

Learn more about incentives for LFG energy in Chapter 4 of LMOP's LFG Energy Project Development Handbook.

LMOP Database

What are the main sources of data for the LMOP Database?

LMOP updates its Database using information voluntarily reported by LMOP Partners, data submitted under EPA's GHGRP, Subpart HH for MSW landfills, and online sources including news articles, press releases, reports and presentations. Information is reviewed for reasonableness and corroborated via other data sources when possible. Not all data are updated each year. While the Program strives to keep the information as updated and accurate as possible, the Database is not exhaustive and does not include data for every MSW landfill in the United States.

Learn more about the LMOP Database.

How often are the Excel files of LMOP data on the website updated?

LMOP publishes updated Excel files of landfill and LFG energy project data on this website two or three times per year to enhance public access to information and support the development of LFG energy projects.

Access Excel files of LMOP data.

How has the number of municipal solid waste landfills in the United States changed over time?

The LMOP Database files list landfill status as open (active and accepting MSW) or closed (no longer accepting MSW), however the LMOP Database is not purported to contain information for all the MSW landfills in the United States. The EPA’s Sustainable Materials Management program’s Facts and Figures report for 2009 (archived) provided active MSW landfill counts by year for 1988 through 2002, 2005 and 2009 in Figure ES-5. In addition, EPA's Inventory of Greenhouse Gas Emissions and Sinks’ Waste chapter notes that the number of active MSW landfills has decreased significantly from approximately 6,326 in 1990 to as few as 1,540 in 2013.

How does LMOP define an LFG energy project expansion?

As part of LMOP’s goal to maintain key technical details as accurately as possible for individual LFG energy projects in the LMOP Database, the Program attempts to track changes in project size (electric capacity, electric output and/or amount of LFG used) over time. The Parent Project ID field uniquely identifies projects and each Parent Project ID has one or more records associated with it. The Parent Project ID field allows the Program to determine a total count of unique projects while the individual project records contain the specific data that allow the calculation of emission reductions on an annual basis.

When an existing LFG energy project’s size increases or decreases, the project gets another record within the same Parent Project ID. These records are identified in the Project Name field as an “expansion” (increase) or “de-expansion” (decrease). For example, if an electricity project originally started with two engines and adds a third engine later, an expansion record is added for the new engine with that engine’s start year, size and other details. Similarly, if an existing electricity project has four engines and two of the engines are removed after a period of time, a de-expansion record is added to accommodate the decrease in the project’s capacity and output and the year it took place.

Access Excel files of LFG energy project data.

How accurate are the latitude and longitude coordinates in the LMOP Database?

The LMOP Database contains the best available coordinates for MSW landfills gleaned from a variety of sources including landfill permits, information directly from landfill owner/operators and mapping tools. The Database is not intended to have exactly precise latitude/longitude values. For example, some coordinates map to the center of a landfill while others map to the entrance. It is likely that most of the coordinates represent physical locations in a WGS84 coordinate system. Data are reviewed on a regular basis and coordinates are updated with more accurate values when available.

How are the data fields named LFG collected, LFG flared and LFG flow to project related to each other?

In many cases, the sum of the LFG Flared and LFG Flow to Project fields for a given landfill will equal the LFG collected. However, in other cases, these fields may not align correctly as every data point in the Database is not updated every year and LMOP receives data from various sources that may conflict. The program attempts to resolve conflicting data and use the best data available for updating the Database. Note that LFG collected, LFG flared and LFG flow to project fluctuate throughout the year and across years; the program tries to “annualize” these values to fit them into a static data field. Much of the data in the LFG Collected and LFG Flared fields originate from EPA’s GHGRP, Subpart HH for MSW landfills. Much of the data in the LFG Flow to Project field originates from LMOP Partners who are involved in the energy project, or the program finds the information from other sources such as news articles, U.S. DOE’s Energy Information Administration or other online sources.

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Last updated on August 29, 2024