Methane is a potent greenhouse gas that is emitted by many industrial and agricultural processes. More specifically, as a byproduct of the oil and gas industry, methane is often flared in order to prevent its release into the environment. However, incomplete combustion and flameouts can lead to methane emissions. Early and reliable detection of these leaks is crucial to prevent harm to both human health and to the environment as well as to support the Federal government in achieving a net-zero carbon economy by 2050. In order to detect flare methane emissions, we propose to construct a laser-based spectrometer that relies on the highly sensitivity technique of dual frequency comb spectroscopy. With this technique, a laser beam with high spatial and temporal coherence is used to probe an environmental path anywhere from a few centimeters to multiple kilometers in length. The spectrum of the laser output will be absorbed by the unique molecular fingerprint of the sample path. Analyzing the absorbed frequencies and the magnitude of the absorption enables the precise determination of the trace gases and concentrations of interest. In this Phase I effort, we will determine the ideal wavelength range that the frequency comb output needs to cover in order to reliably detect the trace gases of interest. We will conduct trade studies to evaluate pathways to reduce the size, weight, power and cost (SWaP-C) of current methane sensing spectrometers, a necessary and important step to facilitate widespread adoption and field deployability. We will then construct a complete, robust and compact dual frequency comb spectrometer system capable of detecting methane and other volatile gases. In a laboratory setting, we will flare methane gas using burners designed to vary the flare efficiency and measure trace species concentrations directly through the flame using the spectrometer system. Field studies on operational oil and gas facilities will be addressed in a Phase II project phase in which we plan to deploy the spectrometers, algorithms, and direct flare monitoring hardware. Our Phase II partner LongPath Technologies will further incorporate the algorithms to populate its real time data dashboard and alerting system for direct customer use.
