Sensitive, Quantitative Standoff Methane Emission Detector and Imager

To reduce anthropogenic methane emissions that contribute to climate change, in March 2014 the White House released the President’s Climate Action Plan’s Strategy to Reduce Methane Emissions wherein a Key Step is “Developing new measurement technologies, including lower-cost emissions sensing equipment.” At a subsequent Gas Processors Association meeting, Dr. Steve Chu, former US Secretary of Energy, added “Lasers are now also the key to inexpensive leak detection for natural gas.” The DoE, EPA, DoT/PHMSA and other Federal agencies are chartered with implementing the plan, and thus the EPA recently proposed rules requiring optical gas imaging surveys of upstream natural gas infrastructure to identify sources of leakage. Current optical gas imaging tools, based on passive thermal infrared detection, visualize large leak sources, but are costly and require trained operators to gather and interpret gas images. As a result, leak inspections at specific sites are infrequent, and can fail to detect intermittent leaks. Furthermore, available infrared imagers are relatively insensitive compared to active laser-based optical sensors and they are non-quantitative, i.e. they do not provide needed methane emission rate information. How this problem is to be addressed: The goal of the proposed R&D project, through Phases I – III, is to create a lower-cost highly-sensitive quantitative natural gas leak survey and imaging tool that meets EPA imaging requirements and measures emission rate. This innovation will combine active backscatter tunable diode laser absorption spectroscopy, passive optical imaging, novel operating techniques and advanced algorithms in a lightweight handheld tool. It will provide quantitative images of path-integrated methane concentration, depicting methane plumes actively interrogated by the laser beam. Emission rates will be calculated from the image information. Phase I Plan: Phase I will build and demonstrate in the laboratory a first prototype of the innovation. The prototype will utilize commercial laser technology (as embodied in commercial leak survey tools developed previously by the proposers) combined with visible/near-IR imaging. Using data gathered by scanning the laser beam, algorithms operating on a laptop computer will create quantified plume images superimposed on scenes of the plume sources. Commercial Applications and Other Benefits: Anthropogenic methane emissions can be controlled and limited if their origins are located. A significant source is leakage from the natural gas system which, in the US, includes more than 700,000 active wells, 300,000 miles of transmission pipelines, and 1,200,000 miles of distribution pipelines. Thousands of leak detection tools and devices are currently deployed worldwide to protect the natural gas system from potentially explosive leaks. The technology to be developed in this project will enhance the ability to protect from environmentally harmful leakage. Key Words: Methane, Leak rate, Flux, TDLAS, Laser sensors, Remote sensing Summary for Members of Congress: Expensive optical gas imaging cameras are currently utilized to identify, but not quantify, sources of leakage in natural gas infrastructure that contribute to climate change. This project will integrate lower-cost laser sensors with video cameras to create highly sensitive methane plume imagers that also quantify emission rate.