152 © 2020 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Correspondence to: Moritz von Cossel, Department of Biobased Products and Energy Crops, Institute of Crop Science, University of Hohenheim, Fruwirthstr. 23, 70599 Stuttgart, Germany. E-mail: moritz.cossel@uni-hohenheim.de In the Field The replacement of maize ( Zea mays L.) by cup plant ( Silphium perfoliatum L.) as biogas substrate and its implications for the energy and material flows of a large biogas plant Moritz von Cossel , Canesia Amarysti, Hanna Wilhelm, Nishu Priya, Bastian Winkler , Lucia Hoerner, Department of Biobased Products and Energy Crops, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany Received November 18 2019; Revised December 22 2019; Accepted December 23 2019; View online February 14, 2020 at Wiley Online Library (wileyonlinelibrary.com); DOI: 10.1002/bbb.2084; Biofuels, Bioprod. Bioref. 14:152–179 (2020) Abstract: Excessive cultivation of maize (Zea mays L.) as a biogas substrate has fred debate about potential land-use change effects of bioenergy cropping systems. Cup plant (Silphium perfoliatum L.) is a perennial biogas crop that provides more environmental services than maize. This study investigated (i) how to replace maize with cup plant as a biogas substrate in a large-scale biogas plant located in southwest Germany, and (ii) how to optimize the energy and material cycles of such a biogas plant given the new feedstock. The biogas plant produces 1000 m 3 biogas per hour with plans for it to be combined with a large dairy farm (1000 dairy units). It was found that the substitution of maize with cup plant as a biogas substrate results in a methane yield reduction of 10% to 20% due to lower biomass yields. However, there exists a strong potential to increase both biomass yields and biogas substrate quality of cup plant by optimizing establishment procedures and better genotypes. Furthermore, cup plant provides food and shelter for open land animals, including birds and insects, and could hence be a suitable alternative to maize for large biogas plants, being more environmentally benefcial. Extracting proteins from cup-plant biomass could also help replace soy with locally produced protein for feeding cattle. Hydrothermal carbonization is a promising tool for closing nutrient cycles and for extracting phosphate from digestate, but more research is needed before it can be put into practice. © 2020 The Authors. Biofuels, Bioproducts, and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd Keywords: bioeconomy; bioenergy; biogas plant; biogas production; circular economy; farmland biodiversity; nitrogen cycling; phosphorus cycling; perennial biomass crops