Portable Mixed Potential Sensors for Natural Gas Emissions Monitoring

The US Environmental Protection Agency has estimated that emissions from natural gas and petroleum systems account for 32% of methane emissions in the US.[1] Natural gas (NG) is transported along hundreds of thousands of miles of pipeline in the US, and any plan to perform continuous monitoring of NG systems for leak detection will require the development of low-cost, field-deployable systems. Mixed potential systems based on ceramic electrolytes and metal or metal-oxide electrodes are expected to be capable of resolving CH4, C2H6 and other sub-components of natural gas mixtures and interferent mixes at the resolution required for buried pipeline monitoring. We have developed additively manufactured mixed potential electrochemical devices which are paired with artificial neural networks to perform mixture identification and discrimination.[2] Deployment of these devices outside of the laboratory setting requires the integration of the sensors into a portable sensor package (Figure 1(a)). We have produced a small form-factor housing for the four-electrode mixed potential device with an integrated heater. This is coupled with an Internet-of-Things data acquisition and networked transmission system to enable recording of the sensor response and transmission to the cloud for processing. The sensor system has demonstrated the capability to resolve simulated natural gas mixtures at the 40 ppm CH4 level (Figure 1(b)). Initial results of testing the sensing system outside the laboratory will also be presented. This work is supported by US Department of Energy, Office of Fossil Energy and Carbon Management award DE-FE0031864. References: [1] US Environmental Protection Agency, National GHG Emissions and Sinks 1990-2000, April 2022. https://www.epa.gov/ghgemissions [2] Halley, S.; Tsui, L.K.; and Garzon, F.H. “Combined Mixed Potential Electrochemical Sensors and Artificial Neural Networks for the Quantification and Identification of Methane in Natural Gas Emissions Monitoring.” J. Electrochem. Soc. 168, 097506. DOI: 10.1149/1945-7111/ac2465. Figure 1. (a) A photograph of a portable sensor package with integrated heater is shown being tested. (b) Sensor response data showing resolution of 40 ppm CH4 in a simulated natural gas mixture in air. Figure 1