The quality of agricultural biogas in Poland against the background of literature reports

The article presents the results of research on the quality of agricultural biogas produced in Poland. The obtained results were compared to the available data published in this field in both domestic and world literature. Samples of purified agricultural biogas were collected in appropriate containers in 11 biogas plants selected for the research, maintaining their representativeness in relation to all agricultural biogas plants in Poland. The agricultural biogas plants selected for the research were objects of various sizes, characteristics of the substrates used and range of parameters to be treated. In these biogas plants, mainly the processes of drying and desulphurizing of the produced agricultural biogas were carried out, in the case of one of the biogas plants, siloxanes were also removed. The determination of the content of carbon monoxide(II), ammonia and the parameters related to biogas humidity was carried out on site due to possible changes in the gas composition resulting from its transport. The remaining quality parameters of biogas were determined in the laboratory. The contents of such substances as: hydrogen, nitrogen, oxygen, carbon monoxide(IV), methane, C2-C5 hydrocarbons, hydrogen sulfide, thiols (mercaptans), siloxanes, alcohols (such as methanol, ethanol and i-propanol), selected monocyclic and polycyclic hydrocarbons were determined in the tested samples of agricultural biogas, as well as organic and inorganic chlorides and fluorides. The research was mainly carried out using the gas chromatography method. Only in the case of determining the content of organic and inorganic chlorides and fluorides the ion chromatography method was used, and in the case of determination of polycyclic aromatic hydrocarbons the method of high-performance liquid chromatography was used. The obtained research results showed that the variability of the composition of agricultural biogas produced in Poland is much lower than that described in the literature (both domestic and global), which contributes to the stability of its energy parameters. It should be added that the content of pollutants that may be present in agricultural biogas determined during the research was also much lower than that provided in the literature data published in this field.