Inspector Gadget: Drones could solve gas-leak detection issue
A methane leak at a Southern California Gas (SoCalGas) storage facility has shone a spotlight on how unmanned aerial vehicles can be used to inspect utilities. The massive three-month leak — temporarily plugged on Feb. 12 — chased thousands of Los Angeles residents from their homes.
At least 2 percent of natural gas is wasted through methane leaks at production sites, according to the U.S. Department of Energy (DOE).
UAVs are already being used for some electrical grid and pipeline inspections, mostly in pilot programs, but their potential for hands-off long-distance monitoring is just starting to be realized.
Along with criminal charges, SoCalGas is facing regulatory mandates to improve air-quality monitoring at its facilities. Nationally, the DOE’s Advanced Research Project Agency-Energy is funding a program to accurately locate and measure methane emissions associated with natural gas production.
The program has given one company, Bridger Photonics, a $2 million grant to develop a leak detector. Bridger plans to build a mobile methane sensing system capable of surveying a 10 x 10 meter well platform in just over five minutes with precision that exceeds existing technologies used for large-scale monitoring.
Bridger’s detector useslaser beams to generate 3D images that show the distance and concentration of a gas leak, even showing the types and concentration of the hydrocarbons.
Mounted on a UAV, the sensor would give inspectors access to complicated or obscured infrastructures at processing plants, drilling rigs and pipelines. The sensor could also be mounted on a vehicle.
Bridger’s goal is for its devices to be able to service up to 85 sites, and cost $1,400 to $2,220 a year to operate per wellsite. Bridger plans to field test its technology this year and make it available commercially in 2017.
Bridger’s imager
Bridger’s gas imager is a point-scanning lidar sensor that performs simultaneous range and gas absorption measurements, according to Mike Thorpe, chief technology officer of Bridger Photonics. The measurements are combined to derive high-accuracy estimates of the gas concentration.
The measurement beam is scanned around the scene to create 3D topographic images of hard targets overlaid with 2D maps of the gas concentration.
The datasets will be geo-registered using GPS and inertial measurements.
The prototype sensor will have the following performance specs:
- 1 kpps measurement rate
- 3-100 m range
- 1 cm down-range resolution
- 2 cm cross-range resolution
- <3 ppm-m methane detection sensitivity for distances < 30 m
- <15 ppm-m methane detection sensitivity for distances < 100 m
Bridger also is developing measurement approaches and algorithms to enable automatic leak detection and leak rate estimation.
A bit of explanation on just how this works would be very educational. Most lasers are single wavelength devices but to gain the data described would require several wavelengths. So there must be a bit more than what is described.