Assessment of grassland as biogas feedstock in terms of production costs and greenhouse gas emissions in exemplary federal states of Germany

Grassland production systems offer feedstock for power production based on biogas in Germany. In the future, additional potential grassland will be made available due to further concentration of cattle production in areas that possess comparative advantages for milk and meat production. This study assesses grassland as a feedstock for biogas production in Germany from both an economic and ecological point of view by considering regional production conditions and plant-specific factors. Regional production costs and greenhouse gas emissions for grasslands are calculated within the federal states of Bavaria, Lower Saxony and Schleswig-Holstein, which represent hotspots for German biogas production. A linear model approach is used to optimize the feedstock mix of each biogas plant located in one of these exemplary regions. In a scenario-based analysis, the opportunity costs for energy crops cultivated on arable land are considered to depict a shortage of arable land as an economic advantage of grasslands. Similar to EU biofuel production, the linear model considers the greenhouse gas mitigation potential for power production based on biogas and differing costs of CO2 emission rights. Greenhouse gas emissions are calculated both with and without iLUC factors to highlight the differences between arable land and grasslands with respect to limited availabilities and the consequences of greenhouse gas emissions. The results show that grasslands could be a reasonable feedstock for biogas production, especially in the northern part of Germany, if iLUC factors are considered and if a greenhouse gas mitigation potential is required that includes high prices for CO2 emission rights.