The Emissions Impact of Gas Mapping LiDAR Scans Compared to the Emissions Detected

Assessing the Environmental Footprint: Comparing Emissions Generated by Gas Mapping LiDAR Scans to Detected Methane Emissions

Here at Bridger Photonics, we are occasionally asked about how the emissions generated from the use of airplanes deployed with Gas Mapping LiDAR™ (GML) sensors compare to the methane emissions that we detect. It’s a great question, so our team ran the numbers to assess the impact.

Emissions from Gas Mapping LiDAR Scans

The CO2 emissions equivalent of a Cessna 172 aircraft, which is typically used for our production sector GML scans, can be calculated using the hourly fuel consumption rate of aviation gasoline. The U.S. Environmental Protection Agency (US EPA) lists Emission Factors for Greenhouse Gas Inventories by fuel type. Using EPA’s reference for mobile fuel consumption, we see that aviation gas emits 8.31 kilograms CO2 per gallon, 0.0071 kg CH4 per gallon, and 0.0001 kg N2O per gallon. The CH4 and N2O values can be converted to CO2 equivalents (CO2e) based on the International Panel on Climate Change’s (IPCC) Fourth Assessment Report (AR4) Global Warming Potential (GWP) values (25x for CH4 and 298x for N2O), resulting in CO2e values of 0.18 kg and 0.03 kg, respectively. Taking the sum of these three greenhouse gases results in an emission rate of 8.52 kg CO2e per gallon of aviation gas. An average of 9 gallons of aviation gas are consumed per flight-hour (FH), yielding total emissions of 76.7 kg CO2e for an hour of aerial scanning. 

Aircraft CO₂e emissions from one hour of GML scanning =

8.52  (kg CO₂e)/gallon × 9 gallons/FH = 76.7  (kg CO₂e)/FH

Emissions Detected during Gas Mapping LiDAR Scans

The aggregate emission rate measured by GML for one hour of scanning, based on the measurement average of several thousand production facilities we scanned in the Permian Basin, is 229 kg/hr of CH4 (including sites with no emissions). This equates to an aggregate CO2e flux detected of 5,725 kg/hr CO2e (based on the same CO2 equivalent of 25x for methane from the AR4 100 year GWP,  like we used above). 

Aggregate detected CO₂ equivalent per hour =

229  kg CH₄/hr × 25x GWP factor = 5,725  (kg CO₂e)/hr/FH
 

Methane Detected vs. Emissions from the Flight

Using the above rates, the ratio of emission flux detected by GML from one hour of scanning to the amount emitted by the aircraft across that hour is 75 : 1 per hour the leak is active.

GML detections over one hour of scanning, based on Permian Basin data
vs.
GML aircraft emissions from one hour to detect those leaks =

5,725 kg (kg CO₂e)/hr / FH ÷ 76.7 (kg CO₂e) / FH = 

75∶1  per hour the leak is active
 

Methane Detected vs. Emissions, Scaled to One Month

The above ratio assumes the leaks are only present for an hour, but many leaks are persistent for much longer than that. Let’s assume leak persistency (the length of time the leaks would have been active if they had not been detected) is one month (30 days). In this case, the emissions generated by the aircraft to detect those leaks remain the same (76.7 kg CO2e per FH), and leaks continue for one month (5,725 kg CO2e per hour x 24 hours per day x 30 days yields 4,122,000 kg CO2e per month). The ratio of the total mass of facility emissions in that month to those emitted by the aircraft over the flight-hour needed to detect them becomes 53,742 : 1.

  GML detections over one hour of scanning, assuming leak persistency of one month
vs. 
GML aircraft emissions from the hour of scanning to detect those leaks = 


4,122,000 (kg CO₂e) ÷ 76.7 (kg CO₂e) = 53,742∶1
 

Of course, these ratios have assumptions built in, such as leak persistency and the average leak rate. The hourly leak rate used here was based off Permian Basin data, but other basins may have higher or lower average emissions. Process emissions may have a variable duration and intermittency, while fugitive emissions, on the other hand, may be persistent for many months until discovered and repaired. Regardless, based on these calculations that assume a one-month persistency for all emissions, the emissions produced by the aircraft during GML scans are a small fraction relative to the emissions that GML can detect, resulting in a huge win for the environment and for keeping valuable gas product in the pipes