Low-cost gas sensing system for the reliable and precise measurement of methane, carbon dioxide and hydrogen sulfide in natural gas and biomethane

We present the design, development and characterization of a novel, low-cost, precise and reliable gas sensor system for the detection of the most relevant gases occurring in natural gas and biogas, namely methane, carbon dioxide and hydrogen sulfide. Especially for the feed-in to the natural gas grid, rigid norms are in place to ensure a constantly high quality of the gas. To allow for a large scale, low maintenance quality control we present a robust approach integrating photoacoustic and metal oxide based gas sensing technologies. Our solution relies on using selective detection technologies for each of the individual gases. Namely, we employ a novel photoacoustic measurement setup to determine the concentration of carbon dioxide and methane with high precision and large dynamic range. To this end, only one light source is used to generate the detection signal. The detection of hydrogen sulfide is accomplished by using copper(II)oxide as gas sensitive material. For the first time a new method to detect hydrogen sulfide with copper(II)oxide is used in an oxygen depleted, near real-world atmosphere. Our results show the viability of employing a detection system for these gases using low-cost components only. This should enable large scale deployment to enhance natural gas quality. The design may be completely integrated into a microsystem.