Development of a low-cost gas sensor network for atmospheric methane concentration monitoring
Typically, the concentration of methane is measured by gas chromatography or by laser-based spectrometry. Both methods are expensive, and cover only a small portion of the spatiotemporal domain of interest: an instrument either measures one, and only one, location continuously, or it is used on infrequent transects, covering a lot of terrain but without recording a continuous evolution of the methane concentration in time.
To fill this gap, we are developing a low-cost methane sensor assembly based on metal oxide sensor technology, which is capable of measuring methane concentrations in the ppm range. This assembly would allow scientists and local communities to continuously collect data on atmospheric methane concentrations at various locations. A network of these sensors could be setup near fracking sites to monitor methane emissions. The main component of the sensor assembly is a Figaro TGS26xx-series gas sensor. As this type of sensor is also sensitive to temperature and relative humidity (rH), we lab-calibrated the gas sensor for its response to these properties, and we continuously monitor ambient temperature and rH during methane measurements. The data are stored locally and are also sent to an online application, myObservatory, where the data are collected, post-processed and published online in real-time.
Here we describe the different assembly components and how they are connected, as well as the procedures and equipment that were used to calibrate the gas sensors with respect to rH, temperature and methane concentration. Finally, we present results from field tests and from sensors deployed near fracking sites in West Virginia.