Technological and energetic evaluation of maize stover silage for methane production on technical scale

Abstract

The aim of this study was technological research of maize stover digestion in an agricultural biogas plant and to determine the parameters of digestion under real-life conditions. The authors calculated the electric and thermal power of the cogeneration system in a biogas plant using maize stover. The load of the digestion mixture was maintained at 12% and the volumetric load (BR) at 3.62 kg LOI/m3/day by applying daily amounts of 3.33 Mg of cow slurry and 109.59 kg of maize stover silage into the digestion chamber. The substrates were mixed at a 9:1 ratio. The daily yield of biogas containing 54.0% of methane amounted to 28.71 m3, i.e. 15.50 m3 of methane daily. The annual yield of biogas from the substrates would have amounted to 10,480.6 m3. This biogas plant using the testing substrates produced 16.5 MWh of electricity and 19.9 MWh of heat per year.Maize stover silage can be used as a substrate in installations for biogas production. However, due to the high content of dry matter and low volumetric density its share in the digestion mixture should not exceed 10–20% to ensure optimal volumetric load in the digestion chamber of the biogas plant.