Research and analysis

Landfill methane: measurement and metrics: summary

Published 2 February 2026

Applies to England

1. Research report summary

This project studied methods for measuring methane emissions from landfills and considered how those measurements could be used in regulation. It investigated how two different measurement methods could be used to demonstrate the effectiveness of landfill gas management. The project found that measurement of emissions could have a potential role in improving the rate of landfill gas capture and reducing methane emissions from landfills.

1.1 Background 

Methane is an important greenhouse gas which is much more potent than carbon dioxide. Methane is one of the main gases produced in landfills as organic waste decomposes, making landfills a major source of anthropogenic methane emissions. It is therefore important that releases of methane from landfill sites are effectively managed to reduce climate impacts.

Landfill gas collection is mandatory in England for permitted landfills accepting biodegradable wastes, however, measuring the residual methane emissions from landfills is difficult because the emissions can come from different sources across a wide area. If we do not know how much uncollected methane is escaping from the landfill, then we do not know how well the landfill gas collection system is performing.

1.2 Approach 

The project used two survey methods to measure the rate of methane emissions: the Tracer Dispersion Method (TDM) and an Unmanned Aerial Vehicle (UAV) mass balance method. In the Tracer Dispersion Method, a tracer gas is released on the landfill at a controlled rate. The tracer gas disperses in the atmosphere in the same way as the methane gas and the ratio of the downwind concentrations of the two gases provides a measure of the ratio of the release rates. For the UAV mass balance method, an UAV is flown in a vertical plane at the downwind boundary of the landfill. Methane concentrations are measured across the methane plume, and the wind speed is used to calculate the rate at which methane is crossing the downwind boundary.

TDM surveys were carried out at four English landfill sites and UAV mass balance surveys were undertaken at three of those landfills. In total there were 20 TDM surveys and 21 UAV mass balance surveys carried out between September 2024 and March 2025.

The operators of each landfill provided operational details and records from their gas collection system for the time of the surveys. This information was examined alongside the survey measurements to understand the performance of the gas collection system. Different metrics of landfill gas management performance were considered for potential regulatory use. The potential metrics evaluated were the measured methane flux, the methane flux per tonne of landfill waste, the methane flux per unit area of the landfill and the methane collection efficiency. 

1.3 Results

The project found that both methods can effectively measure methane emissions from landfill sites, although the techniques may not be useable at all sites, or under all weather conditions. The methane emission results from the UAV mass balance surveys were generally lower than those obtained using the TDM. This is possibly because the UAVs could not fly too close to the ground and so may have missed some methane.

The methane collection efficiency (MCE) was found to be the most suitable metric for landfill gas management performance. This was calculated by dividing the rate at which methane is collected by the rate of methane production. The rate of methane production is approximated by adding the collection and emission rates and the amount of methane that may be oxidised to carbon dioxide in the landfill cover layers. The MCE values calculated at the four sites ranged between 52% and 99%. The lower values were recorded when the landfill gas collection system was not operating correctly at one site. The highest MCE values were measured at one site which showed consistently high levels of MCE throughout the study.

1.4 Conclusions

Methane emission measurements using either TDM or UAV mass balance methods can be used alongside robust gas collection and meteorological data to establish a site’s landfill gas collection efficiency. The methods offer complementary strengths and limitations which suggests that a technology flexible approach would be most effective for regulatory applications, enabling the selection of the most appropriate technique for each specific landfill site.

The MCE values calculated from the survey data were generally able to show changes in gas management at the sites, demonstrating the potential suitability of the metric.

The MCE could be used to benchmark site performance and to trigger any necessary follow-up actions. The Environment Agency would need to consider the most appropriate level of benchmark, or benchmarks, for permitted landfill sites.

Methane measurement surveys should be undertaken under normal operating conditions to ensure that results are representative of typical site operations. The normal operating conditions should be demonstrated through long and short-term data on landfill gas collection rates. A measurement under typical conditions could provide a meaningful demonstration of the effectiveness of the installed landfill gas collection system.

1.5 Publication details

This summary relates to information from project RDE 436, reported in detail in the following output:

• Report: RDE436
• Title: Landfill methane: measurement and metrics
• Project manager: Dave Browell, Environment and Business Directorate, Landfill, Deposit for Recovery and Climate Change Team
• Research contractor: Ricardo

This project was commissioned by the Environment Agency’s Environment and Business Directorate and published by the Chief Scientist’s Group.

Enquiries: research@environment-agency.gov.uk.

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