Integrating pyrolysis-based biocarbon production with sawmills: Heat recovery and techno-economic performance

Biocarbon can replace fossil carbon in hard-to-abate sectors, but its large-scale deployment depends on feedstock availability, production cost, and the effective utilisation of energy-rich pyrolysis by-products. Integration with sawmills may address these constraints by providing access to woody by-products while enabling recovery and utilisation of excess pyrolysis heat. This study evaluates the techno-economic performance of sawmill-integrated pyrolysis-based biocarbon production. Stand-alone and integrated configurations are compared using bark, sawdust, and combined feedstock strategies, focusing on interactions between pyrolysis heat recovery, sawmill heat demand, and biomass allocation. Mass and energy balances were calculated and used as input to a techno-economic model. Sensitivity analyses were performed for char yield and sawmill dryer efficiency, while a scaling analysis assessed the influence of sawmill size on biocarbon production capacity and cost. The results show that integration enables recovered pyrolysis heat to be used in lumber drying, thereby improving energy utilisation and reducing production cost compared with stand-alone production. However, the benefit depends strongly on the balance between pyrolysis heat generation and sawmill heat demand. Higher char yield generally reduces production cost, while lower char yield increases recoverable heat and improves integration performance by reducing on-site bark combustion. Higher dryer efficiency decreases heat demand and external biomass requirements. The scaling analysis shows that integration improves economic performance across plant sizes, but production scale is often constrained by internal sawmill by-product availability. Overall, sawmill-integrated biocarbon production can improve energy, economic and resource performance when plant scale, feedstock strategy, and heat integration are adapted to site-specific conditions.