Reduction and monitoring of biogas trace compounds

For the versatile use of biogas as fuel, it is necessary to remove harmful impurities that affect the utilization as an energy source. The most significant impurities that require removal are corrosion-causing sulphur compounds and organic silicon compounds, in particular, siloxanes. Siloxanes transform into silicon dioxide on the surfaces of gas engines and turbines and thus damage the equipment. The objective of this study was to gather know-how on biogas impurities and their concentration levels as well as the solutions for trace compound removal. In addition, further impacts of impurities on biogas usage from the technical and economic standpoints are discussed. In the study, a literature search was conducted on the existing scientific and economic literature (2000 ?) as well as the patents concerning biogas purification. The information gathered has been substantiated as far as possible by consulting experts in the field. The emphasis of this study was the harmful components of biogas electricity production and especially siloxanes. In addition to the occurrence and removal of biogas impurities, current methods of determining siloxane were evaluated. A new concept for on-line determination of siloxanes in the field was developed. Furthermore, the report presents the biogas matrices at six sites in Finland determined with the developed method.