The importance of high crop residue demand on biogas plant site selection, scaling and feedstock allocation – A regional scale concept in a Hungarian study area

In regions characterised by intensive agriculture, livestock manure is a commonly used feedstock for biogas production. Due to its expensive transportation, manure sources are often the sole criteria during biogas plant site selection, regarding feedstock supply. Encouraging biogas plant operators to use larger amounts of crop residues in the feedstock is favourable from an energy management viewpoint, but its spatial projection on resource logistics and its significance on biogas plant selection is less investigated. In this study, scenarios were created with different feedstock compositions considering constant manure and varying crop residue ratios. Based on their potential biogas yields and the location of livestock farms, a manure source-oriented site selection and facility scaling was made in a Hungarian study area. The applied GIS-based feedstock allocation and logistic analysis defined the crop acquisition possibilities and optimal transportation routes, assuming multiple resource-competitive biogas plants. The results indicate that feedstock composition can indirectly impact the site selection procedure and supply security if high crop residue demand is considered. Resource acquisition possibilities and economic feasibility are significantly affected by the location and density of the proposed biogas plants and their relative position to the crop supply areas. Due to the geographical heterogeneity of the supply side and the demand points, the transportation costs of crop residues and the digestate exceed those of the manure in all scenarios, which draws attention to the importance of spatial availability of crop residues during biogas plant site selection and scaling.