Why Landfill Gas Recovery is Important

Landfill gas recovery is the engineered capture of the gas produced by decomposing waste so that it can be destroyed or put to use instead of escaping to the atmosphere. Landfill gas (LFG) is roughly half methane, a potent greenhouse gas that is also a valuable fuel. Captured and used, it can generate electricity and heat or be upgraded to biomethane. Left uncontrolled, it contributes to climate change, causes odour nuisance and creates fire and explosion risks. This guide explains how landfill gas recovery works, what a recovery system contains, how much gas can realistically be captured, what it costs, how long it lasts, whether landfill gas is toxic, and how it is regulated in the UK.

Landfill Gas Recovery at a Glance

• What it is: collecting landfill gas from the waste mass through wells and pipework, using a blower to draw it to a flare, engine or upgrading plant.
• Composition: about 50% methane and 40–50% carbon dioxide, plus nitrogen, oxygen and trace compounds.
• Climate impact: methane has a 100-year global warming potential of 27.0–29.8 and roughly 80 over 20 years (IPCC AR6).
• Capture rates: depend heavily on cover. US EPA assumptions run from about 60% under daily cover to about 95% under a good final cover. Defra estimates 57% of UK landfill methane was captured in 2024.
• Destruction: flares typically destroy more than 99% of the methane they receive.
• Uses: power generation (about 63% of US projects), direct use as a boiler or kiln fuel (about 17%) and renewable natural gas (about 20%).
• Rule of thumb: roughly 500 m³/h of 50% methane gas supports about 1 MW of electrical output from a gas engine.
• Duration: gas generation declines gradually over decades, so recovery systems must be operated and adapted long after the landfill closes.

Landfill Gas Recovery Meaning: What Is Landfill Gas Recovery?

The landfill gas recovery meaning is simple: it is the process of extracting landfill gas from a landfill under controlled conditions, then treating and either using or flaring it. The terms landfill gas LFG recovery (usually written landfill gas (LFG) recovery), landfill gas collection, landfill gas extraction and landfill gas capture are used almost interchangeably. A “recovery” scheme normally implies that the gas is also put to productive use, whereas a “control” scheme may simply flare it. Both rely on the same collection infrastructure.

Landfill gas forms as bacteria break down organic waste in the absence of oxygen. New waste first passes through a short aerobic stage that produces little methane. Typically within a year or less, anaerobic conditions develop and methane-producing bacteria take over. The phases of this decomposition, and the leachate chemistry that goes with them, are described in our article on methane gas facts and the basic processes of waste decomposition.

Why Landfill Gas Recovery Is Important

The Greenhouse Effect in Brief

Water vapour, carbon dioxide, methane and other greenhouse gases absorb infrared radiation leaving the Earth’s surface and keep the planet warmer than it would otherwise be. Adding more of these gases strengthens the effect. Methane is a particularly efficient absorber, but it is also short-lived, with an atmospheric lifetime of about 12 years. Cutting methane therefore reduces warming within a decade or two, which is why controlling landfill methane is regarded as one of the quickest climate wins in the waste sector.

Landfills Are a Major Methane Source

Waste is one of the three big human sources of methane, alongside agriculture and fossil fuels, and accounts for about 20% of human-caused emissions in the UNEP and Climate and Clean Air Coalition Global Methane Assessment. In the United States, municipal solid waste landfills were the third-largest human-related source of methane in 2022 (about 14.4%), according to the US EPA. In the UK, the waste sector produced around 6% of total greenhouse gas emissions in 2024, and landfill was 55% of that, according to DESNZ statistics. Methane made up 77% of waste-sector emissions, and an 8% fall in landfill emissions between 2023 and 2024 drove most of the sector’s 4% decline.

Modern landfills in most developed countries must operate gas recovery systems, yet a significant fraction of the gas still escapes, and the old, small and closed sites that predate current standards, together with unauthorised dumps, continue to emit. In many industrialising countries there is no requirement to extract gas at all, so project revenue has to fund the infrastructure and carbon finance often plays a role (see our article on carbon credits).

Landfill Biogas Recovery and Its Contribution to Greenhouse Gas Mitigation

Here is what landfill biogas recovery means for greenhouse gas mitigation in numbers. Take a landfill gas flow of 1,000 normal m³/h at 50% methane, running all year. That is about 3,140 tonnes of methane a year, equivalent to about 84,800 t CO₂e if released (using the AR6 non-fossil 100-year GWP of 27.0). If the collection system captures 75% of it (typical of intermediate cover) and the flare or engine destroys 99% of what it receives, the avoided emissions are about 63,000 t CO₂e a year. With a good final cover and 95% capture, the figure rises to about 80,000 t CO₂e. The CO₂ produced by burning landfill methane is biogenic, so under most reporting frameworks it does not count against the project. This is why recovery is such an effective climate measure. For the underlying GWP values see our methane gas facts article.

How Does Landfill Methane Capture Work? The Landfill Gas Recovery Process

Landfill methane capture works by creating a slight vacuum in the waste so that gas flows towards collection points instead of leaving through the surface or migrating sideways. The landfill gas recovery process has seven main steps:

1. Waste decomposes anaerobically and generates landfill gas.
2. Gas forms as a mixture of about 50% methane and 40–50% carbon dioxide, with trace compounds.
3. Extraction wells and horizontal collectors installed in the waste intercept the gas.
4. Wellheads with control valves and monitoring ports allow each well to be balanced and sampled.
5. Header pipework carries gas to a central compound, with condensate drained from low points.
6. A blower or booster applies a controlled vacuum and moves the gas.
7. Gas conditioning removes moisture, particulates and, where needed, hydrogen sulphide and siloxanes before the gas goes to an engine, an upgrading unit or an enclosed flare.

Landfill gas recovery diagram: from decomposing waste to energy use or flaring, with monitoring at the wellheads and flare.

Landfill Gas Recovery System: Main Components

A landfill gas recovery system (sometimes called a landfill gas recovery plant when the compound and utilisation equipment are included) has five main parts.

Landfill Gas Wells and Collectors

A landfill gas well is typically a vertical borehole drilled into the waste, lined with perforated pipe and backfilled with gravel, then sealed near the surface with a low-permeability plug to prevent air being drawn in. Horizontal collectors (perforated pipes laid in trenches within the waste) are used in shallow or active areas, and can be installed during filling so that gas collection starts earlier. Well spacing, depth and design strongly influence capture; see our guide to landfill gas extraction well design, and for simpler, cheaper approaches for shallow or small sites our ebook on pin wells.

Wellheads, Pipework and Condensate Management

Each wellhead has a valve and sampling and monitoring ports. Gas flows through lateral pipes to a header main. Because landfill gas is warm and saturated with water vapour, condensate forms as it cools, so pipework is laid to fall towards drainage points or sumps. High-density polyethylene (HDPE) is the usual material. Poor pipework design and unmanaged condensate are among the most common causes of lost gas flow; see our notes on landfill gas extraction pipework.

Blowers and Boosters

The blower creates the vacuum that draws gas through the system. It must be controlled carefully. Too little vacuum lets gas escape through the surface, while too much draws air into the waste, which dilutes the gas, depresses the methane content and can cause subsurface fires. Good operation is therefore a balance, adjusted well by well using the monitoring data. EPA data suggest blower electricity alone costs about $74,000 a year for a typical landfill extracting 800 cfm (about 1,360 m³/h).

Flares

An enclosed flare is the backstop for any recovery system, and the main control device where gas cannot be used. Flares typically destroy more than 99% of the methane they receive. Because gas flow and quality change over time, flares need to have enough turndown, and the Environment Agency now encourages low-calorific flares for gas that is too weak for an engine. See our article on landfill gas flare monitoring and the flares category.

Gas Conditioning and Utilisation Plant

Engines and upgrading units need cleaner gas than a flare does. Conditioning typically removes moisture and particulates, and can include hydrogen sulphide removal and siloxane removal. Siloxanes form abrasive silica deposits in engines and are one of the biggest threats to engine availability and project returns; see our biogas siloxane articles.

How Much Landfill Gas Can Be Recovered?

Capture efficiency depends on how well the waste is sealed and when the collection system goes in. Field studies cited in our earlier version of this article (Morcet et al. 2003; Spokas et al. 2006) found the following typical recovery rates:

The US EPA uses similar assumptions in its emission estimates: about 60% under daily soil cover, about 75% under intermediate cover and up to 95% under a final cover that meets certain criteria. It also assumes that a share of the methane that escapes is oxidised by bacteria in the cover soil (about 20% without a final cover and 35% with one). In the UK, the national inventory estimates that 57% of landfill methane was captured in 2024, with 52% used for energy generation (Defra parliamentary answer, July 2026).

The factors that move these numbers include landfill geometry, cap material and quality, compaction, waste density and moisture, atmospheric pressure and wind, well design and spacing, waste depth, and how well the system is managed. The most effective things you can do are to install gas collection early, cap promptly with a low-permeability cover, and keep wellfield balancing and repair on a regular schedule.

Landfill Gas Monitoring

Landfill gas monitoring proves that a recovery system is working and that gas is not harming people or the environment. It covers four areas:

• Wellhead monitoring: methane, carbon dioxide, oxygen, temperature, pressure and flow, typically measured monthly (and more often where needed). Permit conditions commonly specify this against Environment Agency guidance, as in this Northern Ireland permit example.
• Surface emissions monitoring: walkover surveys and flux measurements show where gas is escaping through the cap (see LFTGN07 and our guide to methane flux boxes).
• Perimeter and migration monitoring: boreholes and building monitors check that gas is not moving sideways into neighbouring land.
• Engine and flare emissions monitoring: checks on combustion performance and emissions to air (see LFTGN08 for engines).

The Environment Agency is also testing whole-site methods, including tracer dispersion and drone mass-balance measurements, to quantify total site emissions; see the research report Landfill methane: measurement and metrics. For routine procedures see our guide to landfill gas monitoring procedures.

What Is Landfill Gas Used For? Energy Recovery from Landfill Gas

Energy recovery from landfill gas can take several forms. The right choice depends on gas volume and quality, the distance to users and grid connections, and the available incentives.

Landfill Gas Power Plant: Engines and Turbines

Generating electricity is the most common use. About 63% of operational US projects generate electricity, and in the UK landfill gas power is a mature industry: industry commentary puts UK landfill gas generation at about 3.2 TWh with around 400 MW installed under the Renewables Obligation. Reciprocating gas engines dominate because they are efficient and relatively cheap to deploy. Gas turbines and microturbines suit larger and smaller sites respectively. As a rule of thumb, 1 MW of electrical output needs about 500 m³/h of landfill gas at 50% methane, assuming about 40% engine efficiency. For case studies see our article on the landfill power plant, and for engine selection GE Jenbacher vs Caterpillar landfill gas engines.

Combined Heat and Power (CHP)

Combined heat and power captures engine heat as well as electricity, and is typically the most feasible utilisation where there is a heat demand close to the site. It can displace fossil fuels and feed electricity to the grid. Engines generally need gas with a methane content of about 45% or more, so as gas quality declines operators often move to a flare or low-calorific destruction.

Direct Use as a Boiler or Kiln Fuel

Medium-Btu direct use pipes cleaned gas to a nearby industrial user such as a brickworks, greenhouse or boiler. It is energy-efficient but needs a customer within pipeline distance. About 17% of US projects use direct use.

Biomethane and Vehicle Fuel

Gas can be upgraded to biomethane (over 90% methane) for injection into the gas grid, or compressed or liquefied for vehicles. About 20% of US projects now produce renewable natural gas. Waga Energy estimates that moving landfill gas from power to grid injection at the UK’s 100 largest sites could unlock up to 5.5 TWh. Biomethane as LNG does not need proximity to a grid connection, which makes it an option for remote sites. See landfill gas project feasibility for how to assess which option will work.

Landfill Gas Recovery Cost

Landfill gas recovery cost has three layers: the collection and flare system, the utilisation plant and the ongoing operation. The figures below come from the US EPA Landfill Methane Outreach Program’s Project Development Handbook (using LFGcost-Web v3.5). They are in 2020 US dollars, are guidance only, and UK costs will differ, so treat them as indicative orders of magnitude.

• Collection and flare: for a 40-acre wellfield collecting 600 cfm (about 1,020 m³/h), about $1.31 million installed (about $32,800 per acre) and about $221,000 a year to operate. EPA also cites about $2,600 per well and about $5,100 per flare each year for O&M.
• Medium-Btu direct use: gas compression, treatment and condensate management of $730–$1,400 per scfm of capacity, plus pipeline at about $690,000–$880,000 per mile.
• Renewable natural gas: compression and treatment of $6,200–$8,300 per scfm, plus pipeline and interconnection. For an illustrative 2,800 scfm project with a 2-mile pipeline EPA estimates capital of about $16.6 million and annual O&M of about $3.5 million.

Worked Example: A 2 MW Landfill Gas Project

A 600 cfm wellfield (about 1,020 m³/h of 50% gas) supports about 2 MW of electrical output. Using the EPA unit costs:

• Collection system: about $1.31 million capital and $221,000 a year O&M.
• Large engine plant: 2,000 kW × $2,000/kW = $4.0 million capital and 2,000 kW × $300/kW = $600,000 a year O&M.
• Total: about $5.3 million capital and about $821,000 a year in operating cost.
• At 8,000 operating hours, output is about 16,000 MWh a year, so operating cost alone is about $51 per MWh before capital repayment, gas rights or grid connection.

These are illustrative figures, but they show why projects live or die on gas quantity and quality, engine availability and the electricity price or incentive. EPA’s Worcester County example in Maryland is a reminder: a 2 MW project ran from 2008 to mid-2013 and the county has flared the declining gas since. A feasibility study should model gas decline carefully (see the next section) before committing to plant size.

How Long Do Landfills Produce Methane?

Landfills produce methane for decades, and generation continues long after the last waste is tipped. Gas generation is modelled as a first-order decay: it peaks shortly after waste placement (after a short lag while anaerobic conditions develop) and then declines exponentially. The decay rate constant, k, controls how quickly. EPA’s LandGEM modelling guidance illustrates k of 0.02 per year for arid conditions and 0.065 per year for wet conditions. Converting those to practical terms:

These percentages are our own calculation of the generation rate remaining after a given time, from the EPA k values. They show why a wet site yields its gas faster and a dry site stretches it out. For practical purposes, methane from a landfill is typically a multi-decade issue, and many UK landfills that no longer accept waste still produce methane from past deposits. As flows fall, wells in unproductive areas can be capped, blowers turned down and the engine replaced by a smaller unit or a low-calorific flare. For a simple estimate see our landfill gas production rate quick calculation method.

Is Landfill Gas Toxic?

Landfill gas contains toxic components, but its main hazards are fire, explosion and asphyxiation.

• Methane is not toxic but flammable in air at about 5–15% and a simple asphyxiant at very high concentrations.
• Carbon dioxide is an asphyxiant and toxic at high concentrations. Under HSE’s EH40 workplace exposure limits, the long-term limit is 5,000 ppm and the short-term limit 15,000 ppm (check the current edition). It is heavier than methane and tends to accumulate in low-lying and confined spaces.
• Hydrogen sulphide (H₂S) is toxic and has a strong rotten-egg smell. EH40 sets 5 ppm as the 8-hour limit and 10 ppm as the 15-minute limit. The US ATSDR notes that outdoor concentrations near landfills are usually below 15 parts per billion, with no long-term effects identified at these levels, but that workplace exposures can irritate eyes from around 5,000–10,000 ppb and be fatal above 500,000 ppb, typically in enclosed spaces.
• Ammonia and non-methane organic compounds (NMOCs) are present in small amounts. The ATSDR primer (published in 2001, so historical) found studies of low-level exposure near landfills to be inconclusive. Landfill gas has been found to contain as many as 557 trace components.

Operationally, landfill gas migrates through soil and fissures, and because of its carbon dioxide content its density is close to or above that of air, so it can accumulate in cellars, manholes, ducts and cabins. The practical answer is to never rely on smell (methane has none), use calibrated detectors, and follow confined-space and hot-work procedures. See our articles on landfill gas emissions and health and environmental impact.

How Does Landfill Gas Recovery Contribute to Environmental Sustainability?

Landfill gas recovery contributes to environmental sustainability in five ways:

• Climate mitigation: it prevents methane reaching the atmosphere. In the worked example above, a single 1,000 m³/h site avoids tens of thousands of tonnes of CO₂e a year.
• Renewable energy: it converts a waste stream into electricity, heat or biomethane and displaces fossil fuel use.
• Local environmental quality: it cuts odour, reduces the risk of fires and explosions, and limits lateral gas migration and trace-compound emissions.
• Safety and aftercare: well-managed gas control protects people on and around the site and supports restoration and after-use of closed landfills.
• Circular economy: gas projects can fund aftercare costs and use infrastructure that is already in place.

Recovery does not make landfilling of biodegradable waste sustainable in itself. The waste hierarchy still favours prevention, reuse, recycling and diversion of organic waste, which avoids the methane in the first place. But for the waste that is already in the ground, recovery is the most effective control available.

Landfill Gas Recovery in the UK: Regulation and Outlook

In the UK, landfill gas is regulated through environmental permits under the Environmental Permitting Regulations, and the EU Landfill Directive that shaped UK law requires landfill gas to be collected, treated and used, or flared if it cannot be used. The Environment Agency’s overarching guidance is LFTGN03, supported by technical notes on flaring, flare and engine monitoring, trace components and surface emissions.

The Agency’s Methane Action Plan 2024 to 2026 sets out a landfill improvement programme to review gas management systems, development of whole-site measurement methods, a planned leak detection and repair requirement for high-priority sectors including landfill, and work with government to maximise gas capture, destruction and use once Renewables Obligation support for exported electricity ends in 2027. See also our landfill gas regulations category.

For operators the direction of travel is clear: measure total site emissions, find and fix leaks, keep gas collection running as flows decline, and consider biomethane as the electricity incentives wind down.

Landfill Gas Recovery FAQ

What is landfill gas recovery?

It is the process of collecting landfill gas through wells and pipework and sending it to a flare, engine or upgrading plant instead of letting it escape.

How does landfill methane capture work?

Wells and collectors in the waste are connected by pipework to a blower that applies a controlled vacuum. The gas is conditioned and then burned in an engine or flare, or upgraded to biomethane.

How much landfill gas is recovered?

It depends on the cover and the system, from about 35% in an operating cell to over 90% under a good final cover. Defra estimates 57% of UK landfill methane was captured in 2024.

What is landfill gas used for?

Mainly electricity generation, plus heat, direct use in industry, biomethane for the grid and vehicle fuel.

Is landfill gas toxic?

It contains toxic trace components, notably hydrogen sulphide, but the main hazards are explosion, asphyxiation from methane and carbon dioxide, and the build-up of gas in confined spaces.

How long do landfills produce methane?

For decades. Generation peaks soon after waste is placed and then declines exponentially, so gas control often has to continue for many years after closure.

Need Help With Landfill Gas Recovery?

If you need independent engineering advice on landfill gas collection, monitoring, flaring or energy recovery, use our contact form to ask for a free quotation from IPPTS Associates. You may also find our collection and extraction articles useful.

References and Further Reading

1. US EPA Landfill Methane Outreach Program. Basic information about landfill gas; Landfill gas energy project data; Continue to operate gas collection system and flare.
2. US EPA LMOP. Project Development Handbook, Chapter 4: Project economics and financing (LFGcost-Web v3.5 costs, 2020 US$), and Chapter 2: Landfill gas modeling.
3. Environment Agency and SEPA. LFTGN03: Guidance on the management of landfill gas; LFTGN07; LFTGN08.
4. Environment Agency. Methane Action Plan 2024 to 2026; Landfill methane: measurement and metrics; Manage landfill gas.
5. DESNZ statistics via LetsRecycle (February 2026). Waste sector greenhouse gas emissions fall by 4% in 2024.
6. Defra parliamentary answer (17 July 2026). Landfill methane capture in 2024.
7. Waga Energy (June 2025). Unlocking the potential of landfill biomethane in the UK.
8. ATSDR. Landfill gas primer, Chapter 3 (2001, historical).
9. HSE. EH40/2005 Workplace exposure limits (current edition).
10. IPCC (2021). AR6 Working Group I, Chapter 7 (methane GWP).
11. Morcet et al. (2003); Spokas et al. (2006); Haubrichs and Widmann (2006); Huber-Humer (2007): field recovery rates and the greenhouse effect, as cited in the previous version of this article.

[Updated October 2026 (first published November 2012).]