Case Studies of Environmental Impacts from Agricultural Biogas Systems with Regard to Global Warming

The utilization of the different renewable energy sources in Germany has expanded in the last twenty years, where the renewable share in gross power consumption has gone from 5% to 35%. The construction of biogas plants, for instance has increased almost 10 times since 2000 to 2018 that the installed electrical power reached 4.8 GW. This paper presents an evaluation of the Life Cycle Assessment (LCA) of four biogas plants in different soil climate regions in Bavaria. The article discusses the different utilization, management and share of feedstocks (manure and energy crops) in the biogas plants and their influence on the electricity generation and the GHG emissions, whereas the biogas plant with higher share of energy crops and maize silage, in particular, showed higher GHG emissions and generated more electricity than the biogas plants with higher share of manure. The produced GHG emissions as a result of the electricity and heat supply from the biogas plants have been compared with the emissions that are created from the German grid mix and the different fossil fuels for generating electricity and heat