Advanced biorefinery integration in kraft pulp mills: BECCS pathways, commercial failure analysis, and the carbon price threshold for subsidy-free viability

Kraft pulp mills are increasingly viewed as strategic platforms for decarbonization because they combine biogenic carbon flows, chemical recovery infrastructure, and opportunities for heat and material integration within a circular bioeconomy. However, prior reviews have focused mainly on gasification and have given less attention to integrated carbon capture, high value product routes, commercial failure lessons, and pathway specific economic thresholds. We critically reviewed sources published from 2018 to 2025 using the ROSES framework and a standardized reference case of a 1000 ADt/day bleached kraft mill. The synthesis compared black liquor gasification, lignin and hemicellulose valorization, heat integration, and bioenergy with carbon capture and storage using exergy, greenhouse gas, techno economic, and technology readiness evidence. Results show that black liquor gasification-based systems can increase exergy efficiency from about 40% for conventional recovery boilers to about 44% in integrated configurations, while system expansion studies report net greenhouse gas intensities of about 0.3 to 0.6 t CO 2 below zero per tonne pulp for selected fuel and chemical pathways. Carbon capture can deepen decarbonization, but the outcome is route specific: post combustion MEA systems typically achieve about 0.3 to 0.9 t CO 2 below zero per tonne pulp, whereas pre combustion capture integrated with black liquor gasification and water gas shift can reach about 0.8 to 1.5 t CO 2 below zero per tonne pulp where transport and storage infrastructure exist. Economic performance remains highly sensitive to product price, capital cost, utilization rate, and carbon price.