Life cycle assessment of wood pellet from para-rubber tree residues: Cradle to grave

This study focuses on the Life Cycle Assessment (LCA) of wood pellets made from para-rubber tree residues. The scope of the study is cradle to grave, covering para-rubber tree plantation, wood pellet production, and heat production by a boiler (capacity 3 t/h). The environmental impacts were assessed throughout the para-rubber tree wood pellet production chain, including the comparison of wood pellets with conventional biomass and fossil fuels. The SimaPro software (v. 8.5.2.0) was used for the LCA and the ReCiPe2016 Midpoint/Endpoint method (version 1.02) was chosen to evaluate the environmental impacts of heat production from para-rubber tree wood pellets. The contribution of heat production is more than 65% to many of the environmental impact categories considered including stratospheric ozone depletion, ozone formation, fine particulate matter formation, terrestrial acidification, freshwater eutrophication, and human non-carcinogen toxicity. Moreover, the contribution of transportation is over 60% in global warming, terrestrial ecotoxicity, marine ecotoxicity, human carcinogen toxicity, and fossil resource scarcity. As anticipated, the life cycle greenhouse gas emissions or global warming for heat production from para-rubber tree wood pellet (including wood pellet and waste wood) are lower than fossil fuels (coal, natural gas, diesel and residue fuel oil). The greenhouse gas emissions of the former are almost twenty times lower than their fossil equivalents. Most of the other impact categories are also lower for the wood pellets except for freshwater eutrophication, land use, mineral resource scarcity, and water consumption which are higher. The result of comparison of endpoint impacts of 1 GJ heat production from wood pellet, conventional biomass and fossil fuels shows that the wood pellets have lower impacts than the fossil fuels (coal, natural gas, diesel and residue fuel oil) for human health (15.76 DALY), ecosystem quality (11.54 species.yr) as well as resource scarcity (9.18 USD2013).