Wood pellet as biofuel: a life cycle analysis of a domestic and industrial production chain

This study focuses on the environmental impact assessment through Life Cycle Assessment (LCA). In particular, the aims are to compare the environmental impacts of ‘‘A1 premium’’ wood pellet manufacturing in a large industrial plant with “domestic” wood pellet manufacturing in a small pelletiser, and to identify the environmental hotspots of these two pellet productive chains. The raw material, for both systems is maritime pine wood. A cradle-to grave life-cycle inventory is used and, thus, the system boundary began with the forest stage and ended with ashes disposal after pellet burning. For the forest stage, two scenarios were simulated (intensive and extensive). Moreover, in a sensitivity analysis, alternative scenarios were tested for pellet burning (higher and lower emissions) and for transports (higher distances). The results underline that electricity consumption due to machinery used for the compressing phases of pelletising process has a key role in the environmental profile, together with pellet burning. The production of the wood has a low impact if compared with the other main stages of the pellet production chain. The sensitivity analysis revealed that transport distances have a great impact in the ozone depletion category and climate change, especially when a high transport distance is assumed. Moreover the sensitivity analysis demonstrated that the pellet burning stage has a large impact, even when low emissions are adopted. The industrial model, with high emissions assumed for pellet burning is the worst scenario in terms of environmental performance. The model with less overall environmental impacts is the domestic model, with low emissions for pellet burning and extensive forest management. The comparison between the domestic and industrial model shows that, the domestic model performs better, having better performances on 6 impact categories out of 8.