Biogas plants are one of the most stable sources of renewable energy. Currently, there is a noticeable increase in the amount of post-production residues from agricultural production and agri-food processing (fruit and vegetable processing, fermentation, beet pulp, or lignocellulosic waste), which, can be used for biogas production after appropriate pretreatment. The aim of this study was to examine the possibility of using the biomass produced during the cultivation of grapes on a selected farm as a substrate for a biogas plant, taking into account the production process. The research was carried out in 2018–2020 in a vineyard located in the Sandomierz Upland in the south-eastern part of Poland. Own rooted vines were grown as a single continuous string with a trunk height of 40 cm and a length of one fixed arm approx. 0.9 m, on which six pivots were left every year after applying a short cut, from which 12–16 fruit shoots were derived, the so-called grapevines. Leaves were collected at random from three locations on the fruiting shoot, a total of 30 leaves in each replicate. Each sample consisted of 1/3 of the leaves collected at the bottom, 1/3 in the middle, and 1/3 at the top of the canopy. Leaf area was estimated with a model 3100 area meter on a sample of 30 leaves from each replicate. Both the quantity and quality of the obtained material as a substrate for methane fermentation were evaluated. Biogas yield tests in optimal conditions for mesophilic bacteria were conducted on three substrate samples referred to as ‘Regent’, ‘Seyval Blanc’, and ‘Solaris’. The yields of the tested material ranged from 51.0 to 59.0 Nm ³ biogas per Mg of biomass.

Anaerobic digestion is a demanding process, due to the large number of process and environmental factors that affect it. Many years of research of the various parameters have made it possible to optimise the process to obtain the maximum amount of biogas and methane contained in it, and this provides energy and environmental benefits. The article deals extensively with the operation of agricultural biogas plants, using the example of a plant that faces numerous operational problems. In order to identify the negative effects on energy yield and the equipment operating in the system, the substrate was examined, the data on its operation analysed, and solutions were proposed that should be taken into account in the further operation of the biogas plant. The analysis showed a good biogas yield from beet pulp of 563 dm³∙kg⁻¹ of TS (total solid) and an average methane yield of 58%. With the analysis presented, it was possible to identify some operational problems. The biogas yield study also highlighted some errors made at the plant design stage. The most important of these is the use of an inappropriate organic matter loading factor for the digester, which leads to acidification of the contents and degradation of the methanogenic microorganism cultures.