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Remote methane sensor for emissions from pipelines and compressor stations using Chirped-laser Dispersion Spectroscopy
Project Number
DE-FE0029059
Last Reviewed Dated
Goal

The goal of the project is to develop, test, and field demonstrate a remote sensing methane (CH4) detector for use on aircraft and vehicles to detect leaks along midstream infrastructure of the natural gas supply chain.

Performer

Princeton University, Princeton, NJ 08544 
American Aerospace Technologies, Inc., Conshohocken, PA 19428

Background

Fugitive CH4 leaks from the natural gas supply chain to the atmosphere mitigate the climatic benefits of switching away from other fossil fuel sources, but large measurement challenges exist in identifying and quantifying CH4 leak rates along the vast number and type of components in the natural gas supply chain. This is particularly true of the "midstream" components of gathering, processing, compression, transmission, and storage. In contrast to sampling well pads where spatial length scales are on the order of 10 m, the length scales of midstream components are immense. Nearly 500,000 km of transmission pipelines form a complex network across the U.S. Distributed at various points along these networks are another 700,000 km of gathering pipelines, 600 processing plants, 1,400 transmission compressor stations, and 400 underground storage units nationwide.

The large areal and linear extents of midstream infrastructure create sampling challenges. Mobile laboratories are limited to the road network and favorable (downstream) wind directions when, for example, sampling processing/compressor stations. Ground‐based measurements and tracer approaches also require favorable meteorological conditions. Because significant amounts of CH4 are emitted into the compressor station exhaust, the warmer and more buoyant plumes often will not be captured by ground‐based techniques.

To address the plume lofting and large length scales for midstream sampling, this project will develop and deploy a novel remote sensing CH4 sensor from either light aircraft or a mobile laboratory. This will involve sensor refinement, field testing, and algorithm development; validation experiments on a vehicle and then aircraft with controlled releases of CH4; and flights along pipeline corridors in the Mid‐Atlantic and Marcellus Shale region to demonstrate commercial readiness. 

aircraft

 

Impact

The key innovation is heterodyne enhanced chirp modulated chirped laser absorption spectroscopy (HE‐CM‐CLaDS), an approach that uses optical dispersion rather than absorption to detect atmospheric CH4. Instead of detecting changes in light intensity as in an absorption-based measurement like all existing optical sensors, HE‐CM‐CLaDS detects the phase shift of laser light resulting from optical dispersion. One of the key advantages to this approach is its strong signal intensity, a feature that is critical for a backscattered approach where near‐infrared light is collected from a wide range of surfaces and ground cover. Remote standoff detection means the technique will be capable of deployment on a vehicle or aircraft for large area scanning such as an overflight of a pipeline corridor or around gathering or compressor stations. Finally, HE-CM-CLaDS provides a range‐resolved signal that allows for 3D tomographic images with appropriate sampling/scanning design.

Because the HE‐CM‐CLaDS sensor can be used to send trained personnel to a specific, targeted pipeline site to fix a given leak, the anticipated benefits are saved labor and travel costs, improved pipeline safety, and reduced pipeline explosions, resulting in fewer injuries/deaths and less property damage. This will benefit pipeline companies and operators by mitigating costs associated with fines, liability, and legal fees. In addition, industry will benefit from system-wide recovery of otherwise lost product. Finally, by providing a remote sensing leak detection technology for companies, leaks along the natural gas supply chain will be mitigated more efficiently and less CH4 (and other associated hydrocarbons) will escape into the atmosphere, resulting in improved air quality and a reduced climatic footprint.

Accomplishments (most recent listed first)
  • The Princeton team has implemented a lower frequency acoustic optical modulator (AOM) and real-time field-programmable gate array (FPGA) processing in the HE-CLaDS system, which allows for the demodulation of both HE-CLaDS signal and direct CLaDS signal using a single FPGA platform.
  • Outdoor testing and validation of system performance has been conducted on the Princeton campus. By introducing calibrated flows of CH4 along a 5-meter long, 12-inch diameter PVC pipe, sensitivity of the system has been validated. These tests demonstrate the linearity of the system, as well as the sensitivity of the measurement to the location of the leak along the laser path.

PVC Pipe

  • A portable optical system for remote sensing of CH4 has been developed and configured into a transportable system. The system can be easily switched between conventional CLaDS and HE-CLaDS operation mode. All the preliminary lab performance results confirm that the system is on trajectory to meet the desired specification requirements that include: sensitivity of <1 ppmv-m/Hz-1/2 CH4 in atmospheric air, range-finding resolution of <0.1 m, and optical heterodyne enhancement of at least 10 dB when compared to direct optical detection.
  • Design is underway of the collecting optics to maximize power collection and allow auto-refocusing and optimal reflected signal from a moving target on an unmanned autonomous vehicle. The lens design will be integrated with the collecting optics for conventional CLaDS and the HE-CLaDS systems.
Collecting optics for a) CLaDS and b) HE-CLaDS with auto-focusing signal provided by the camera.
Collecting optics for a) CLaDS and b) HE-CLaDS with auto-focusing signal provided by the camera.
  • Implemented ranging capability using a field-programmable gate array (FPGA), which will be used to integrate all functions of the CLaDS system in a single data acquisition and control system. Laboratory testing of the ranging capability has been initiated to test its compatibility with various CLaDS techiques.
Current Status

Current efforts are focused on finalizing outdoor testing and validation of the system, to be followed by vehicle-mounted mobile field tests.

Project Start
Project End
DOE Contribution

$1,141,204

Performer Contribution

$285,299

Contact Information

NETL – Robert Vagnetti (robert.vagnetti@netl.doe.gov or 304-285-1334)
Princeton, University – Dr. Mark A. Zondlo (mzondlo@princeton.edu or 609-258-5037)

Additional Information

Quarterly Research Progress Report [PDF] July - September, 2018

Quarterly Research Progress Report [PDF] April - June, 2018

Quarterly Research Progress Report [PDF] January - March, 2018

Quarterly Research Progress Report [PDF] October - December, 2017

Quarterly Research Progress Report [PDF] July - September, 2017

Quarterly Research Progress Report [PDF] April - June, 2017