Methane leak detection and methane quantification are two distinct tasks with different goals, methods, and outputs. Detection identifies where a leak exists along a pipeline or at a facility, while quantification measures how much methane is escaping from a specific source. Both are essential parts of a complete LDAR programme, but they are not interchangeable, and understanding the difference matters more than ever as EU methane regulation tightens requirements for gas network operators across Europe.
How does methane leak detection actually work?
Methane leak detection is the process of scanning gas infrastructure to identify the presence and location of methane emissions. A detection survey answers one core question: is there a leak here, and where is it? The output is a spatial record of gas indications, typically mapped along a pipeline route or across a site, flagging locations that require follow-up action.
Modern detection methods range from ground-based walking surveys using handheld sensors to vehicle-mounted systems and airborne platforms. Airborne methane detection, in particular, has transformed large-scale pipeline inspection by enabling operators to survey hundreds of kilometres in a single day. Laser-based systems using the Differential Absorption LIDAR (DIAL) method emit two laser pulses at different wavelengths and measure how much methane absorbs each pulse. This allows the system to detect even very small concentrations of gas along the survey corridor without requiring physical contact with the pipeline.
The key performance metrics for a detection survey are sensitivity (the smallest leak rate the system can reliably identify), survey speed, and spatial resolution. For pipeline inspection services, these factors determine how thoroughly and efficiently an operator can cover their network within a given inspection cycle.
What does methane quantification mean in practice?
Methane quantification is the measurement of the actual emission rate from a known source, expressed in volume or mass per unit of time, for example litres per hour or kilograms per year. Where detection tells you a leak exists, quantification tells you how significant it is. This distinction is critical for prioritising repairs, reporting emissions data, and demonstrating compliance with regulatory thresholds.
Quantification requires a more controlled measurement approach than detection. The system must account for wind speed and direction, atmospheric dispersion, and the geometry of the source. Airborne quantification methods typically involve flying a series of transects around or downwind of a source to build a concentration profile, which is then combined with meteorological data to calculate the total emission flux.
For gas transmission and distribution operators, quantification results feed directly into emissions inventories, regulatory reporting, and decisions about repair urgency. A large leak at a compressor station and a small seep from a valve fitting may both be detected in the same survey, but their quantified emission rates will drive very different responses.
Why can’t the same survey deliver both detection and quantification?
Detection and quantification require different flight patterns, measurement durations, and data processing approaches, which makes combining them into a single pass technically difficult and often impractical. A detection survey is optimised for coverage, moving quickly along a route to flag anomalies. Quantification requires slower, repeated passes around a confirmed source to build the data density needed for an accurate flux calculation.
Think of it like a medical analogy: a screening scan identifies which patients need further investigation, while a diagnostic test measures the severity of what was found. Trying to do both simultaneously would compromise the quality of each. In airborne methane surveys, attempting to quantify every detected indication in real time would dramatically slow the survey and reduce the area that can be covered per flight hour.
This is why best practice in LDAR programmes typically separates the two tasks: a detection survey covers the full network to identify all leak locations, and targeted quantification missions are then deployed to priority sites where emission magnitude needs to be established.
When does EU methane regulation require quantification versus detection?
EU Regulation 2024/1787 on methane emissions in the energy sector distinguishes between detection surveys and source-level quantification as separate regulatory obligations. Detection surveys, referred to as LDAR surveys in the regulation, are required at defined intervals across above-ground and underground components. Quantification is required when detected emissions exceed certain thresholds or when operators need to report site-level emission data as part of their transparency obligations.
The regulation introduces a tiered approach. Routine LDAR surveys focus on identifying leaks and triggering repair obligations. However, for larger facilities and for operators contributing to national methane inventories, quantified emission data is required to demonstrate compliance with emission limits and to populate the reporting frameworks the regulation establishes.
Importantly, the regulation has significantly shortened inspection intervals compared to previous national standards in many EU member states. This means operators need faster detection technology to maintain full network coverage within the new timelines, while also building quantification capability for the sites where regulatory reporting demands it. Understanding which obligation applies to which asset class is essential for building a compliant LDAR programme in 2026 and beyond.
Which technologies are used for each task?
Detection and quantification each draw on a range of technologies, with the right choice depending on the scale of the survey, the type of infrastructure, and the sensitivity required.
Technologies commonly used for detection
- Differential Absorption LIDAR (DIAL): Laser-based airborne method capable of detecting leaks from 150 litres per hour at survey speeds up to 180 km/h, suitable for large-scale pipeline network surveys
- Optical Gas Imaging (OGI): Infrared cameras that visualise gas plumes, typically used at above-ground installations and component-level inspections
- Flame Ionisation Detectors (FID): Ground-based handheld instruments used for walking surveys of distribution networks
- Vehicle-mounted laser systems: Drive-by detection for urban distribution networks, covering road-accessible routes efficiently
Technologies commonly used for quantification
- Airborne flux quantification: Repeated transect flights downwind of a source combined with meteorological data to calculate total emission rate
- Tracer correlation: A known quantity of tracer gas is released near the source and measured downwind alongside the methane signal to derive the emission flux
- Mass balance methods: Used at facility level, measuring methane concentrations at the boundary of a site to calculate net emissions
- High-flow samplers: Ground-based instruments that measure concentration and flow velocity at the point of emission for component-level quantification
Should pipeline operators run detection surveys before quantification?
Yes, in almost all cases, detection should come before quantification. Running a detection survey first identifies which locations actually have emissions, allowing quantification resources to be directed precisely where they are needed. Attempting to quantify emissions across an entire network without prior detection would be extraordinarily time-consuming and costly.
The logical sequence for a well-structured LDAR programme is straightforward:
- Conduct a network-wide detection survey to map all gas indications
- Prioritise findings by location, proximity to population, and regulatory classification of the asset
- Deploy quantification at sites where emission magnitude is needed for repair prioritisation or regulatory reporting
- Initiate repair workflows based on combined detection and quantification data
- Conduct verification surveys post-repair to confirm successful remediation
This sequenced approach makes the most efficient use of inspection budgets and ensures that the highest-emission sources are identified and addressed first. For operators managing thousands of kilometres of transmission and distribution pipelines, the ability to cover large areas rapidly in the detection phase is the critical bottleneck. Faster, more sensitive airborne detection directly enables a more responsive quantification and repair programme downstream.
How ADLARES supports methane detection and quantification
We provide end-to-end airborne solutions for both methane leak detection and emission quantification, helping gas network operators meet their LDAR obligations efficiently and at scale. Our CHARM® technology is the world’s only DVGW-approved airborne gas remote detection system, and it has been used to inspect over 250,000 km of gas pipelines across Europe since entering commercial service in 2008.
Here is what we offer across both tasks:
- Large-scale detection surveys: CHARM® surveys pipelines at speeds up to 180 km/h at altitudes of 100 to 150 metres, detecting leaks from 150 litres per hour, enabling rapid full-network coverage within shortened EU regulatory inspection intervals
- Methane Emission Quantification (LDAQ): Targeted airborne quantification missions for confirmed emission sources, delivering the flux data operators need for regulatory reporting and repair prioritisation
- EU Methane Regulation Type 2 compliance: CHARM® provides the sensitivity required to comply with underground equipment requirements under EU Regulation 2024/1787
- Secure Web GIS reporting: Survey results are delivered through a secure Web GIS platform accessible on desktop and mobile, so your team can verify findings and act on gas indications without delay
Whether you need to survey a single pipeline corridor or your entire transmission network, we can design a programme that integrates detection and quantification in the most efficient sequence for your operational and compliance needs. Contact ADLARES to discuss how we can support your LDAR programme in 2026 and beyond.