Environmental life cycle assessment (LCA) in Poland is still a relatively new method of estimating the environmental impact of production processes. It enables the assessment of the environmental risks associated with the product system or activity, either through the identification and quantification of materials and energy used and waste introduced into the environment, as well as assess their impact on the environment. LCA method application also enables the calculation of greenhouse gas emissions in accordance with Directive 2009/28/EC on the promotion of energy from renewable sources. This paper presents the results of the simplified life cycle analysis of electricity production process from agricultural biogas used as an engine fuel. LCA analysis was conducted based on data from one of the national biogas plants. The selection criterion was based on the availability of substrates (maize silage, distillery slop and sugar beet pulp) and the possibility of obtaining high quality data for analysis (actual data based on the existing biogas plant). In addition, the environmental impact of the biogas power generation technology obtained through the methane fermentation process only of waste materials (distillery slop, sugar beet pulp) and coprocessing of waste and maize silage was compared.