Towards carbon-negative biomass conversion: Life cycle assessment of a pyrolysis plant with integrated CO2 capture via chemical looping combustion

Climate strategies increasingly require carbon dioxide removal (CDR). While biomass pyrolysis stores biogenic carbon in biochar, conventional volatile handling limits its environmental performance. This study presents an ISO-conformant life cycle assessment (LCA) of a pilot-scale woody biomass pyrolysis system intensified with CO 2 capture via chemical looping combustion (CLC) of the volatile fraction. Unlike purely theoretical models, this assessment leverages primary empirical data from both pilot-scale pyrolysis and small-scale CLC operations, ensuring a technically robust environmental inventory. Using a mass-based functional unit of 1 kg dry biomass, five configurations are compared: standalone pyrolysis (Cases A-B), pyrolysis with pyrogases combustion (Cases C1-C2), and pyrogases oxidation via CLC with CO 2 capture (Case D). Impacts are evaluated across 16 EU Environmental Footprint (EF) midpoint indicators and normalized to population equivalents. Results demonstrate that thermal integration and volatile management systematically improve the environmental profile. Configurations oxidizing volatiles achieve net-negative global warming potential (GWP), with Case D providing the strongest net-removal signal (1.357 kg CO 2 /kg biomass). Notably, Case D reduces the GWP (−0.74 kg CO 2 /kg biomass) compared to the standard combustion configuration in Case C2 (−0.24 kg CO 2 /kg biomass). Furthermore, normalized lifecycle results reveal that Case D delivers environmental advantages over Case C2 across all evaluated non-climate categories, with the sole exception of Resource Use (RU). Ultimately, while biochar provides primary carbon storage, CLC integration unlocks the maximum additional removal potential. These findings position CLC-intensified pyrolysis as a high-performance CDR technology, highlighting the value of comprehensive LCA in validating integrated carbon-negative pathways.