Comparing Fixed and Mobile Methane Monitoring: A Comprehensive Guide

Every methane program eventually collides with the same two questions: where do you look, and how often? Mobile tools answer the first brilliantly and the second poorly. Fixed monitoring does the reverse. This guide lays out the facts, the trade-offs, and why the smartest programs build their foundation on always-on instrumentation.

The single trade-off that explains everything

Strip away the jargon and methane monitoring reduces to a contest between two dimensions: spatial coverage and temporal coverage. Spatial coverage is how much ground you can survey. Temporal coverage is how much of the time you are actually watching. No single instrument on the market maximises both, and the entire fixed-versus-mobile debate is really an argument about which of the two matters more for a given asset.

This matters because of one stubborn fact that now organises the whole field. Research published in Science in 2024, and summarised across the monitoring literature, established that roughly 5 percent of facilities generate more than half of the oil and gas sector’s methane, and they do it through super-emitter events that are intermittent and unpredictable. A seal fails, a hatch sticks open, a flare goes unlit. These events can run for hours, days, or weeks, and they account for the bulk of the damage. Methane is responsible for around 30 percent of the rise in global temperatures since the Industrial Revolution and traps heat more than 80 times as effectively as carbon dioxide over a 20-year window, according to the IEA’s Global Methane Tracker 2025. When the worst emissions are episodic and the molecule is this potent, when you are watching turns out to matter at least as much as where.

Keep that tension in mind as we walk through the two families of technology. Everything else follows from it.

The mobile family: maximum reach, minimum dwell time

Mobile monitoring covers everything that comes to the emissions rather than waiting for them: a person, a vehicle, a drone, an aircraft, or a satellite that surveys a site and then moves on. The family spans an enormous range of scale and cost, so it helps to take it in tiers.

Handheld and close-range survey

The original tool, and still the regulatory reference point, is the technician on foot. Optical gas imaging (OGI) cameras render methane plumes visible in infrared, and handheld analysers following the U.S. EPA’s Method 21 procedure probe individual components at close range. Nothing beats a handheld instrument for pinpointing exactly which valve or flange is leaking. The weakness is structural: it is brutally labour-intensive, covers only what the surveyor physically reaches, and captures a single snapshot of a site that may look very different the following week. Manual surveys are the backbone of most leak-detection-and-repair (LDAR) regulations because they are precise, and the limit of most LDAR regulations precisely because they are infrequent.

Vehicle-based mobile survey

Mount the same sensing principles on a truck and you trade some localisation precision for speed, driving a road network with a downwind analyser to flag elevated concentrations across a field. It is faster than walking and useful for screening, but it remains weather-dependent, road-dependent, and episodic.

Drones (uncrewed aerial vehicles)

Drones have matured quickly into a serious screening and inspection tool, especially for hard-to-reach or hazardous infrastructure such as flare stacks, offshore platforms, tank tops, and long pipeline runs. Two sensor types dominate. Tunable diode laser absorption spectroscopy (TDLAS) units, such as the widely deployed Pergam Laser Falcon, fire a laser at the asset and read reflected light: one commercial integration documented by SPH Engineering reliably detects 500 ppm from at least 40 metres, which meets the EU Methane Regulation’s Type 2 above-ground LDAR criterion, and 1,000 ppm from 60 metres for the underground criterion. The second type is the airborne OGI camera, including long-wave infrared units built to satisfy the EPA’s OOOOa/b/c and Appendix K standards. Drones survey in hours what would take a ground crew days, keep people out of dangerous areas, and carry a low cost per inspection. Industrial platforms now offer flight times stretching past four hours on hybrid power for long-range pipeline work. The catch is the same as every mobile tool: a drone flies a mission and then lands. It tells you what was leaking during the flight, not at 3 a.m. on a Tuesday.

Crewed aircraft

Fixed-wing and helicopter platforms fitted with imaging spectrometers screen entire basins in a single campaign, and the technology is now genuinely mature. A landmark single-blind controlled-release study, published and peer-reviewed, evaluated five major aircraft platforms (Carbon Mapper, GHGSat-AV, Insight M, MethaneAIR, and Scientific Aviation) across more than 700 metered releases over six weeks. Aircraft consistently quantified emissions above 10 kg/h, and two platforms detected releases below 5 kg/h, with blinded quantification estimates tracking actual release rates closely. Aircraft campaigns are excellent for finding the big, intermittent emitters across a wide area on a periodic basis. They are not continuous, they require pilots, permissions, and clear weather, and the cost per campaign scales with how often you fly.

Satellites

At the top of the spatial pyramid sits a constellation of more than 25 active methane-monitoring satellites, as catalogued by EESI. They split into two complementary classes. Area flux mappers such as the European Space Agency’s TROPOMI (on Sentinel-5P) image most of the planet’s land daily but at kilometre-scale resolution, with a high detection threshold that only catches very large emissions; theoretical single-source thresholds for these wide-area instruments run into the several-tonnes-per-hour range. Point-source imagers see far less ground but resolve individual facilities: a review in Atmospheric Chemistry and Physics places sensors like GHGSat, PRISMA, Sentinel-2, and WorldView-3 in the 100 to 10,000 kg/h band, with GHGSat detecting around 200 kg/h and the Carbon Mapper Coalition’s Tanager-1 satellite resolving roughly 90 to 180 kg/h. The strength is breadth and independence: satellites can flag a super-emitter anywhere on Earth without an operator’s cooperation. The limits are revisit frequency, cloud cover, and a detection floor that lets all but the largest leaks slip through.

A cautionary note on the satellite tier’s fragility: MethaneSAT, the high-profile mission launched in March 2024 by the Environmental Defense Fund and the New Zealand Space Agency to bridge the gap between wide-area and point-source observation, lost contact and was declared a loss in June 2025 after roughly a year of operation. Remote sensing is powerful, but space hardware is unforgiving, and no operator should build a compliance strategy on a single orbital asset.

What unites the mobile family

For all their range, every mobile tool shares one defining limitation: each is a snapshot in time. Whether the snapshot is taken from a worker’s hands or from low Earth orbit, it tells you what was happening during the survey window and is silent about everything that happens between visits. For a problem dominated by intermittent events, that silence is where the emissions hide.

The fixed family: permanent watch over chosen ground

Fixed monitoring inverts the design. Instead of bringing the sensor to the emissions, you install instruments on or around an asset and leave them running. You sacrifice the ability to roam, and in exchange you gain something no mobile tool can offer: time.

The main types are point-sensor networks (metal-oxide or laser-based detectors distributed across a site and networked together), open-path or fenceline laser spectrometers (a beam shot across a perimeter that integrates concentration along its path), fixed OGI cameras, and scanning laser systems. The commercial field has consolidated around a handful of approaches: as the climate-tech outlet CTVC catalogued, Qube uses continuous infrared sensing, LongPath Technologies uses open-path laser spectroscopy, and QLM uses lidar, among others.

The performance question is no longer theoretical. A single-blind controlled-release study of eight commercial continuous monitoring systems, published in ACS ES&T Air, ran for 45 days against simulated high-volume venting. Every system held its false-positive rate under 10 percent, and half exceeded an 80 percent true-positive rate on the largest releases. That is a real, independently verified result, with the honest caveat that performance varies between systems and that turning a concentration reading into a quantified emission rate still leans on wind data and modelling. Different fixed approaches also have different sweet spots: fenceline lasers excel at catching large plumes but struggle to pinpoint the exact source, while close-proximity point sensors localise better but need denser deployment. There is no one-size-fits-all device, which is why the leading reporting frameworks stay deliberately technology-neutral.

What every fixed system delivers, regardless of type, is temporal coverage. It is watching at 3 a.m. on that Tuesday. That single property reshapes the economics, as we will see.

Head to head: the comparison that matters

Here is how the two families stack up across the dimensions operators actually weigh.

The dimension that decides most real cases is temporal coverage, and the evidence here is stark. A three-year study of regulated LDAR programs in British Columbia, published in ACS ES&T Air, found that three-times-a-year OGI surveys cut detected emissions roughly in half at fully compliant sites, yet independent aerial surveys over the same sites found twelve times more methane overall. Compliance was high. The periodic approach still missed the overwhelming majority of the gas, because a quarterly survey leaves a 90-day window in which a single malfunction can release hundreds of tonnes unobserved. Mobile tools cannot close that window. Fixed tools are the window.

The cost question, examined honestly

The objection to fixed monitoring is always the upfront capital. It is a fair point and a real number. Installing a networked sensor system or a fenceline laser array costs far more on day one than dispatching a contractor with an OGI camera twice a year. If you stop the analysis there, mobile looks cheaper. The analysis should not stop there.

Consider how costs behave over an asset’s life. Mobile monitoring carries a low entry price but a recurring one: every survey, every flight, every campaign is a fresh invoice, and to catch intermittent emissions you have to survey more often, paying repeatedly for snapshots that still miss the events between them. The marginal dollar buys progressively less certainty. Fixed monitoring front-loads the spend and then runs at low marginal cost, watching continuously without a new invoice for each observation.

Then weigh what continuous data is worth when something goes wrong. The clearest illustration comes from the way methane fees are structured. As Qube Technologies has detailed, under the U.S. super-emitter framework the default assumption when a large release is detected, absent contrary data, is that it ran for 182 days. A quarterly OGI program can argue the event started the day after the last inspection, cutting the assumed duration to about 91 days. An operator with an approved continuous monitoring system can demonstrate a time-to-detection of roughly seven days. The difference between a fee built on 182 days and one built on 7 is not a rounding error. It is the whole business case in a single line, and it exists only because fixed data can prove how long a leak actually lasted.

Layer on the rest of the ledger. Every tonne caught early is gas recovered and sold rather than vented; the IEA estimates that around 30 percent of fossil-sector methane could be abated at no net cost, because the value of the captured gas exceeds the cost of capturing it, and that almost all abatement measures pay off at a carbon price of just 20 dollars a tonne of CO2-equivalent. For oil and gas specifically, roughly 30 percent of emissions could be cut today with measures returning more than 25 percent, well above the hurdle rate these companies apply to ordinary projects. Add avoided reputational damage from being named a public super-emitter, the defensibility of continuous records in front of regulators and investors, and the emerging premium for certified low-methane gas, and the supposedly expensive option becomes the cheaper one over the life of the asset. The upfront cost of fixed monitoring is, in fact, the easiest number in the entire equation to defend.

The regulatory backdrop tilts toward measurement

Whatever an operator’s instincts, the rules are converging on continuous, measurement-based data. The United Nations Environment Programme’s Oil & Gas Methane Partnership 2.0 sorts reporting into five levels, where Levels 4 and 5 require company-specific measurement and site-level reconciliation rather than generic estimates. The European Union’s Methane Regulation, built directly on that framework, mandates source-level monitoring and reporting, requires LDAR across all facilities, and reaches across borders: importers filed first reports in May 2025, new contracts must show equivalent measurement standards from January 2027, methane intensity reporting begins in 2028, and from 2030 imported gas must fall below a maximum intensity threshold to enter the market at all. As the Oxford Institute for Energy Studies has mapped, this turns high-quality site-level data from a virtue into a market entry requirement. Mobile screening can support detection and Level 3 reporting; reaching Level 4 and 5, and proving compliance to a European buyer, leans heavily on the kind of continuous, reconcilable record that fixed systems are built to produce.

The verdict: build on fixed, screen with mobile

The honest conclusion is that with the options on the market right now, no one family wins outright. The families answer different questions, and a mature program uses both in a deliberate hierarchy.

Using mobile and remote sensing as the reconnaissance layer. Satellites and aircraft scan wide areas to find where the large emitters are; drones and handhelds move in to localise, inspect hard-to-reach equipment, and confirm a repair. This layer is unbeatable for breadth, for screening assets you have not instrumented, and for independent verification.

Then anchor the program on fixed continuous monitoring at the highest-risk and highest-value assets, the compressor stations, processing facilities, and large well pads where an intermittent failure does the most damage and where the fee math, the recovered gas, and the regulatory exposure are greatest. This is the layer that closes the temporal gap, catches the events that dominate the emissions profile, and generates the defensible, reconcilable data that the OGMP framework and the EU regulation increasingly demand.

A practical way to choose the mix: the higher an asset’s emission risk, the longer the cost of an undetected leak, and the heavier its regulatory exposure, the stronger the case for permanent instrumentation rather than periodic visits. A sprawling, low-risk gathering network might be screened economically from the air. A critical facility feeding an export contract should be watched without blinking. Spatial breadth is the job of mobile tools. Temporal certainty is the job of fixed ones. The programs getting this right are not choosing between them. They are putting fixed monitoring at the core, where being there at 3 a.m. on a Tuesday is worth more than any snapshot, and letting mobile tools do what they do best around it.

Sources

1. International Energy Agency, Global Methane Tracker 2025, Key Findings (warming share, potency, emissions scale): https://www.iea.org/reports/global-methane-tracker-2025/key-findings
2. IEA, Global Methane Tracker 2025, Understanding methane emissions (no-net-cost abatement, carbon price): https://www.iea.org/reports/global-methane-tracker-2025/understanding-methane-emissions
3. “Comparing Continuous Methane Monitoring Technologies for High-Volume Emissions: A Single-Blind Controlled Release Study,” ACS ES&T Air (eight fixed systems): https://pubs.acs.org/doi/10.1021/acsestair.4c00015
4. “The Efficacy of Methane Leak Detection and Repair (LDAR) Programs in Practice,” ACS ES&T Air (British Columbia 12x undercount): https://pubs.acs.org/doi/10.1021/acsestair.5c00195 (open access: https://pmc.ncbi.nlm.nih.gov/articles/PMC12624710/)
5. “Technological Maturity of Aircraft-Based Methane Sensing,” single-blind evaluation of five aircraft platforms: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11154951/
6. “Quantifying methane emissions from the global scale down to point sources using satellite observations,” Atmospheric Chemistry and Physics (satellite detection thresholds): https://acp.copernicus.org/articles/22/9617/2022/
7. Environmental and Energy Study Institute (EESI), satellite super-emitter detection and MethaneSAT loss (June 2025), 25+ active satellites: https://www.eesi.org/articles/view/out-of-this-world-methane-detection-using-satellites-to-track-super-emitters
8. Waste Dive, GHGSat fleet expansion and confirmation of MethaneSAT loss: https://www.wastedive.com/news/ghgsat-methane-satellite-launch-cop30/806773/
9. SPH Engineering, drone TDLAS (Pergam Laser Falcon) detection specs and EU Methane Regulation Type 2 LDAR thresholds: https://www.sphengineering.com/integrated-systems/technologies/methane-detection
10. CTVC, overview of the fixed/continuous monitoring vendor landscape (Qube, LongPath, QLM): https://www.ctvc.co/inside-methane-monitorings-big-moment/
11. Qube Technologies, methane-fee time-to-detection analysis (182 / 91 / 7-day comparison): https://www.qubeiot.com/expert-insights/mitigating-risk-with-continuous-monitoring-under-the-new-methane-fee-and-super-emitter-program
12. UNEP Oil & Gas Methane Partnership 2.0 (five reporting levels): https://www.ogmpartnership.org/
13. IEA policy summary, EU Methane Regulation: https://www.iea.org/policies/18209-eu-regulation-on-the-reduction-of-methane-emissions-in-the-energy-sector
14. Oxford Institute for Energy Studies, EU Methane Import Requirements (2025): https://www.oxfordenergy.org/wpcms/wp-content/uploads/2025/03/ET44-EU-Methane-Import-Requirements.pdf

Note: the “5 percent of facilities, 50 percent of emissions” figure traces to research published in Science (2024); the MethaneSAT specifications (100 x 400 m resolution, launched March 2024) and the Carbon Mapper Tanager-1 figures are drawn from the satellite reviews cited above. Readers needing the primary Science citation should consult its 2024 super-emitter quantification studies directly.