Assessing circular economy strategies for wheat straw pyrolysis valorization in Chilean agriculture

Agricultural residues represent an underutilized resource with strong potential for circular economy models that support the transition toward more sustainable agricultural systems. This study evaluated circular strategies for wheat straw valorization using Life Cycle Assessment (LCA), following ISO 14040/14044, ReCiPe 2016, and the Circular Flow Index (CFI). Five scenarios were assessed: linear and semi-loop configurations, and three closed-loop pathways including cogeneration and biofuel production by bio-oil hydrotreating and their integration (combined scenario). Biochar recirculation enabled carbon sequestration (559 kg CO₂eq per ton of wheat straw) and reduced mineral fertilizer use by 8 %. The combined cogeneration-hydrotreatment configuration showed the lowest climate change impact (-288 kg CO₂eq per ton of straw), and reduced the fossil resource scarcity by 14 %, and the overall environmental damage (16.0Pt). As circular strategies were implemented, energy circularity increased from 0 % in the linear system to 15.7 % under cogeneration and 38.5 % in the cogeneration-hydrotreatment pathway, while material circularity remained low (0.062 %) because irrigation water dominated system inputs. These results demonstrate that pyrolysis-based circular strategies can improve the environmental performance of agricultural systems, while highlighting that the magnitude of these benefits depends on trade-offs between energy recovery pathways, combustion-related emissions, and upstream hydrogen demand.