Methane Monitoring Is Just Getting Started

With the recent launch of MethaneSAT and the existing constellation of other satellites capable of detecting anomalous methane emissions from orbit, there may be a temptation to believe that we must now have all the methane monitoring technology needed to combat methane-induced climate change.

While satellites are, indeed, an important part of the arsenal of methane sensing technologies that will be needed, they are by no means sufficient. For instance, while satellites can cover large areas, they do so with relatively low revisit cadence (~ 1 week in the case of MethaneSAT) and during each revisit only take a single snapshot in time. In other words, satellite coverage is extremely temporally discontinuous. 

They also have limited spatial resolution and sensitivity: they typically can only identify very large leaks of >100 kg/hr (~20x the traditional lower limit of the super-emitter leak definition: 5% of sites with the highest emission rates are responsible for 60% of total methane emissions) and can only localize leak sources to the asset level (e.g. Carbon Mapper has a 30 meter x 30 meter resolution; MethaneSAT has a 100m  x 400m resolution). 

These capabilities are impressive and useful to find the biggest persistent leaks. However, they overlook more common leaks in the 5 – 100 kg/hr range that comprise a significant fraction of total leaked methane. Further, their spatial resolution is insufficient for exact source attribution: for example, a ground technician may need to scour an entire square kilometer with a handheld sensor to pinpoint the source of a leak detected by MethaneSAT.

In summary, it is very useful for the whole world to be monitored by satellites - but satellites are only a coarse filter, capable of indicating problems but with little information about leak rate, source, or duration.

Fortunately, other technologies are available to supplement satellite data. Overflights by fixed-wing or other aircraft using hyperspectral imaging or LiDAR can find smaller leaks and with sufficient spatial resolution to pinpoint leak sources. Bridger Photonics is one leading solution offering very useful data for many operators in oil & gas and other markets. Unfortunately, frequent campaigns can get very expensive and most operators are only willing to pay for this service a few times per year. 

Therefore, overflights tend to be even less frequent than satellite visits, so although the data are still very useful and can identify troublesome sources over a wide area, the measurement cadence is insufficient to provide anything other than a snapshot in time.

Ground-based sensors overcome many of the limitations of satellites and airborne technologies by providing continuous measurements at a particular site or in a particular area. They are typically the most sensitive methane detection technologies and can provide information on both the source locations and quantities of the methane leaked. However, most ground-based sensors measure at a single point in space like a “nose”, thus relying on the wind to blow methane towards the sensors and an internal pump to draw samples into the sensors. (And unfortunately these moving parts introduce multiple points of failure.)

Other newer ground-based sensors use optical, open-path geometry and often ingenious variations of tunable diode laser spectroscopy to provide path-integrated measurements over a series of fixed paths. The path-integrated nature of the measurements allows them to sample a much larger area effectively relative to point sensors; in other words, these function as “eyes” instead of “noses”. They tend to be the most sensitive of the technologies, capable of detecting small leaks < 0.5 kg/hr. Some variations can cover large areas (10s of km2) with a single system. However, these systems are generally very expensive, pricing them out of most site-level applications and limiting their use case to high-density O&G production assets.

This is the gap that TrelliSense’s sensors are filling today. Our sensors are:

• Continuous  ||  Averaging over 5- or 10-second frequencies

• Optical  ||  “Eyes” rather than “noses”

• Ground-based  ||  post- or wall-mounted and self-powered

• Long-range  ||  Multiple square kilometers of range

• Low-cost  ||  Roughly 10x cheaper than other continuous optical solutions

One sensor uses the sun as our spectroscopic light source; thus, the sensor’s line of sight is pulled by the sun through the sky above an asset, thus acting like a “methane radar”. The sweeping, dome-like line of sight is unique in the industry and allows identification, location, and quantification of leak sources with less recourse to model-based data analytics.

However, using the sun as a light source limits collection to daytime hours with partial sunlight (which is still more than 300 days per year in most locations). Therefore, we have developed a proprietary artificial broadband light source that mimics the sun’s spectral output (x100) in the near-infrared wavelengths. Our sensor can also use this light source to fix lines of sight and locate and quantify methane leaks on a 24/7 basis in a similar fashion to the open-path technologies mentioned above - but at a fraction of the cost. Our low cost enables applications in more cost-sensitive and isolated facilities such as upstream/abandoned wells, mid/downstream gas, landfills, cattle feedlots, coal mines, industrial facilities, and many more.

Over the long term, we both hope and expect that each of these types of monitoring technologies - satellites, aerial flyovers, OGI cameras, contact-based sensors, and path-integrated optical - gains widespread adoption for applications best suited to their strengths. There is no one silver bullet for all methane monitoring, and therefore they will all have their place. That said, we are on a mission to prove that TrelliSense will be a “prime mover” in the market, and will fill today’s significant gap in cost-effective, continuous and site-wide methane leak detection, localization and quantification.

Check out our home page to learn more about our technology and its applications, and feel free to email us at info@trellisense.com to schedule a conversation.