Life Cycle CO2 Emissions and Techno-Economic Analysis of Wood Pellet Production and CHP with Different Plant Scales and Sawdust Drying Processes

This study presents a life cycle assessment (LCA) and economic analysis of wood pellet production and utilisation in gasification combined heat and power (CHP) systems, focusing on optimising the drying process and evaluating the impacts of varying plant scales. In line with Japan’s target of achieving net-zero emissions by 2050, the research examines primary energy demand (PED), CO2 emissions, and financial viability across the wood pellet production (gate-to-gate) and CHP energy generation (gate-to-grave) stages. The results reveal that the drying process accounts for 35–39% of the total energy consumption in wood pellet production, with the heat source significantly influencing PED and CO2 emissions. Systems employing wood-fired boilers and wood pellet CHP for drying achieve reductions in PED by 12–26% and CO2 emissions by 14–31% compared to the conventional grid-supplied drying process. Economic analysis reveals that scaling up production enhances financial performance, with net income increasing by up to 20% and payback periods reducing to approximately 10 years in facilities producing 2.5 tons of wood pellets per hour. These findings highlight the critical role of optimised drying processes, plant scalability, and efficient supply chains in advancing sustainable wood pellet-based bioenergy systems that support Japan’s renewable energy targets.