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Cradle-to-Grave Life-Cycle Assessment of Wooden Pallet Production in the United States 21 Table 17—Scenario analysis for global warming impact of use phase on wooden pallet transportation for 100,000 lb (45.4 metric tons) of pallet loads of product delivered with wooden pallets Low Average High Distance (km) 25 50 100 Transport metric a (t.km) 9.88E–01 1.98E+00 3.95E+00 GHGs per functional unit b (CO 2 eq) 9.35E–02 1.87E–01 3.74E–01 a Used pallets transported by diesel tractor trailers. b Emission factor is 0.0946 kg CO 2 eq/t.km Table 18—Biogenic carbon inventory indicators Additional inventory parameters Unit Total A1 A2 A3 B2 C Biogenic carbon removal from product kg CO 2 –79.36 –79.36 — — — — Biogenic carbon emission from product kg CO 2 76.63 — — 14.65 — 61.99 Biogenic carbon removal from packaging kg CO 2 –1.13 — — –1.13 — — Biogenic carbon emission from packaging kg CO 2 1.13 — — — 1.13 — Biogenic carbon emission from combustion of waste from renewable sources used in production kg CO 2 0.00 — — 0.00 — — contributor to the GW impact of lumber manufacturing. Adoption of new drying technologies [i.e., the progressive (continuous flow) dryers] can lead to greater environmental performance (Bergman 2021, Bond and Espinoza 2016). The disposal (end-of-life) stage [C], which includes the portion of wooden pallets disposed to landfills, has minor contribution to overall environmental impacts. 4.2 Uncertainty and Sensitivity Analysis Sensitivity analysis is performed to identify the parameters that have great influence on the environmental impact of the system. Defining sensitive parameters may help mitigate the potential sources for uncertainties. In this study, the sensitivity analysis was performed by altering the selected parameters by 20%. The selected parameters included the electricity input, amount of fasteners used, and amount of wood material input to the wooden pallet manufacturing system [A3]. The results of the sensitivity analysis are presented in Table 20. The increase in wood material input had the greatest effect on the GWP results, about 12% output variance. Conversely, a 20% increase in other two parameters resulted in a small variation in the GWP impact of about 2% to 3%. 4.3 Limitations The industry-average LCA was performed in this study using weight-averaged primary data from U.S. wooden pallet manufacturers. The wide variety of wooden pallets manufactured in the U.S. industry makes development of the industry-average wooden pallet LCI a complex task. Focusing on the highest production pallet, the GMA- style pallet with the 48- by 40-in. footprint, the RSL and load carrying capacity of four pallet types were used to calculate the FU. Therefore, weight load capacity and durability had great influence on the overall environmental performance. Including the repair–remanufacturing stage to perform cradle-to-grave analysis requires accounting Table 19—Cradle-to-grave life-cycle impact contribution analysis for 100,000 lb (45.4 metric tons) of pallet loads of product delivered Core mandatory impact indicator Unit Total (%) A1 (%) A2 (%) A3 (%) B2 (%) C (%) GWP kg CO 2 eq 100 34 23 35 7 <1 AP kg SO 2 eq 100 49 22 23 5 <1 EP kg Neq 100 9 4 79 8 <1 SP kg O 3 -eq 100 48 27 20 5 <1 ODP kg CFC11eq 100 42 2 47 9 <1 FD MJ surplus 100 36 32 24 8 <1

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