Among the renewable energy technologies, biogas plants are particularly interesting since they offer a reliable, steady source of electricity and heat. Both the composition as well as the quality of the biogas are crucial parameters for monitoring and optimizing the complete process chain. Currently employed systems only allow for ex-situ measurements using complex extraction machinery. Furthermore, due to their high cost a widespread use is prevented, especially in small biogas plants. To overcome these deficiencies and enable a continuous, reliable and precise determination of the gas composition innovative sensor systems are much needed. This contribution presents a novel in-situ approach capable of measuring the gas concentration of the most important biogas components continuously and in real time. This is achieved by using a combination of metal oxide based gas sensing and a photoacoustic detection scheme.
