Environmental and energetic evaluation of biogas production from plant biomass

Abstract

Environmental and energetic evaluation of biogas production from plant biomass is presented in the paper. Environmental assessment of biogas production technology has been analysed in terms of life cycle assessment methodology and energetic evaluation has been performed including direct and indirect energy inputs of soil tillage, cultivation, sowing, fertilization, yield harvesting, transportation, ensiling and digesting to biogas. Perennial grasses - cocksfoot grass (Dactylis glomerata), reed canary grass (Phalaris arundinacea) and tall fescue grass (Festuca arundinacea) have been investigated. It is determined that emissions of direct energy input during the digestion tall fescue grass and reed canary grass – 0,069 and 0,067 kgCO2/ kg biomass were the highest. The highest gas leakage found to be in the cocksfoot grass biomass digestion case - 0,072 kgCO2/kg biomass. Results of analysis of total energy input for plant biomass show energy input of 0,714 MJ/kg biomass for tall fescue grass, 0,755 MJ/kg biomass – reed canary grass and 0,869 MJ/kg biomass – cocksfoot grass. Energy potential of cocksfoot grass, tall fescue grass and reed canary grass have been found to be 4,03, 4,03 and 3,37 MJ/kg biomass respectively. These results suggest that cultivation of perennial grasses and anaerobic digestion to biogas is energy efficient and environment friendly way of renewable energy creation.