Fig. 1

System boundary of the study, including agriculture operations for biomass production (maize and willow), transport and storage, biomass conversion (anaerobic digestion (AD) and pyrolysis), and final gas upgrading along with by-product (digestate and biochar) handling operations. There were two willow scenarios: in willow scenario a, the biochar was returned to agricultural land, and in willow scenario b, the biochar was used as an energy source