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Frequency Combs for Methane Detection

University of Colorado, Boulder (CU-Boulder)
ARPA-E Award: 
Boulder, CO
Project Term: 
05/08/2015 to 11/10/2020
Project Status: 
Technical Categories: 
Critical Need: 
The recent expansion of domestic natural gas production, particularly from shale resources, has improved the economic, security, and environmental outlook of our nation's energy portfolio. Unfortunately, at least 2% of this gas resource is wasted through leaks of methane, the main component of natural gas, at production sites. Methane is a potent greenhouse gas (GHG) if emitted directly to the atmosphere, and methane emissions from natural gas development may undermine the climate benefits of using lower carbon natural gas for power generation. Existing methane monitoring devices have limited ability to cost-effectively, consistently, and precisely locate and quantify the rate of methane emissions. Affordable sensing systems would enable more effective methane mitigation programs, which could lead to a reduction in overall methane emissions and more efficient extraction and use of domestic energy resources.
Project Innovation + Advantages: 
The University of Colorado-Boulder (CU-Boulder) will team up with the National Institute of Standards and Technology (NIST) and the Cooperative Institute for Research in Environmental Sciences (a partnership between CU-Boulder and the National Oceanic and Atmospheric Administration) to develop a reduced-cost, dual frequency comb spectrometer. The frequency comb would consist of 105 evenly spaced, sharp, single frequency laser lines covering a broad wavelength range that includes the unique absorption signatures of natural gas constituents like methane. The team has shown that frequency comb spectrometers can measure methane and other gases at parts-per-billion concentration levels over kilometer-long path lengths. Current, long-range sensing systems cannot detect methane with high sensitivity, accuracy, or stability. The team's frequency combs, however, are planned to be able to detect and distinguish methane, ethane, propane, and other gases without frequent calibration. When integrated into a complete methane detection system, the combs could lower the costs of methane sensing due to their ability to survey large areas or multiple gas fields simultaneously. When employed as part of a complete methane detection system, the team's innovation aims to improve the accuracy of methane detection while decreasing the costs of systems, which could encourage widespread adoption of methane emission mitigation at natural gas sites.
Potential Impact: 
If successful, CU-Boulder's frequency combs could be a useful component of more cost-effective and accurate methane monitoring systems for natural gas producers.

Better methane detection technologies could improve the sustainability of domestic natural gas production and the safety of operations.


Enhanced detection sensors could enable greater mitigation of methane leakage and lead to an overall reduction in harmful methane emissions associated with natural gas development.


Since the team's frequency combs could be used to survey large areas with greater accuracy, the innovation could lower the expense of large-scale methane monitoring.

Innovation Update: 

(As of May 2018)

The CU-Boulder team has developed a regional methane detection system that combines field ruggedized, autonomous dual-comb spectrometry (DCS) with inversion modeling to locate and measure leaks. The team was able to miniaturize and ruggedize the optics by utilizing digital controls to achieve quick phase locking between combs and developing a feedback system to stabilize the two combs. The team also developed multiple new inversion methods utilizing different gas transport models and statistics-driven observation configurations to overcome challenges associated with long-path inversion modeling. The system can successfully locate extremely small methane emissions from a distance of more than 1km and it is on track to achieve a tenfold monitoring cost reduction per well per year.


The team has met with dozens of potential customers and partners and identified upstream oil and gas production and natural gas storage as viable commercial uses. They have spun out a company, Longpath Technologies, to provide natural gas emissions monitoring as a service for the oil and gas industry.


For a detailed assessment of the CU-Boulder project and impact, please click here.


ARPA-E Program Director: 
Dr. Joseph King
Project Contact: 
Prof. Gregory Rieker
Release Date: