Optimizing torrefied rubberwood pellets for sustainable bioenergy: Industrial application, eco-efficiency, and carbon mitigation

The global shift towards sustainable bioenergy demands not only improved biomass upgrading methods but also credible validation of their techno-economic and environmental feasibility at an industrial scale. Torrefaction has long been recognized for enhancing biomass fuel properties, yet a persistent challenge lies in translating laboratory results into viable, large-scale applications. This study addresses that challenge by introducing an integrated “optimization-to-application” framework for torrefied rubberwood sawdust pellets (TSP). The framework combines four complementary approaches: (1) laboratory-scale process optimization using a Central Composite Design (CCD) in Design Expert software (DE), systematically varying temperature, time, and initial moisture content due to their critical impact on torrefaction performance; (2) industrial-scale mass and energy balance simulations to evaluate process efficiency and heat recovery; (3) a GIS-based logistical assessment for optimal plant siting; and (4) a cradle-to-grave Life Cycle Impact Assessment (LCIA) to quantify environmental outcomes. Laboratory trials identified optimal torrefaction conditions (274.6 °C, 20min, 6% initial moisture), producing TSP with a higher heating value of 21.51MJ/kg, an energy densification ratio of 1.16, and a projected mass yield of 89.5%. Scaling these parameters to an industrial model with a heat recovery efficiency of 71.4% reduced production costs from $223.78 to $203.49 per ton, while lowering process-related CO2 emissions by 43.5% (229.39kg CO2/ton). The resulting Economic Environmental Index (EEI) improved by 162%. A sensitivity analysis using actual operational data from the facility revealed that the LCIA further confirmed notable reductions in global warming potential of 21.29% for plywood/RSP processing, and 38.43% for TSP production. GIS analysis pinpointed a plant location that cut transport costs by 29% compared with a non-integrated site. Collectively, these results demonstrate a practical pathway for deploying TSP as a sustainable industrial fuel. Replacing coal with TSP at a single large-scale cement facility could yield an estimated $86.4million annually in carbon credit value, underscoring both the economic and environmental significance of this transition.