Environmental footprints of British Columbia wood pellets from a simplified life cycle analysis

摘要

Purpose Environmental footprints of wood pellets produced in British Columbia (BC) of Canada are to be estimated based on industry surveys and published emission factor data. Method The streamlined life cycle analysis starts from raw material acquisition and ends at port Rotterdam in Europe for exported pellets or North Vancouver port for domestically used pellets. The raw materials used for pellet production are dry and wet sawmill residues, and allocations are based on dry mass. The pellet production data are based on three pellets mills in western Canada. Results and discussion For every tonne of BC pellets exported, 295 kg CO_2 equivalent greenhouse gases is released. The human health, ecosystem quality, and climate change impacts of the exported pellets can be reduced by 61%, 66%, and 53%, respectively, if the pellets stay in BC for local applications. Harvesting is the second highest impacting process, following marine transportation. The total amount of primary energy consumed for 1 tonne of exported pellets is 6,372 MJ, and approximately 35% of it is attributed to marine transportation. Exported pellets have 16.4% of nonrenewable energy content and an energy penalty of 33% with energy penalty defined as the amount of primary energy consumed to produce and deliver one unit of process energy using the higher heating value. For domestically used pellets, the energy penalty is 21% and the nonrenewable energy content is 8.59%. Conclusions Marine transportation is the main contributor for all impact categories. Improving the energy efficiency of the harvesting and pellet plant operations is also a way to effectively reduce these wood pellet's environmental footprints.