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Table 3 Variable input parameters used in the sensitivity and uncertainty analyses

From: Life cycle greenhouse gas emissions of ethanol produced via fermentation of sugars derived from shrub willow (Salix ssp.) hot water extraction in the Northeast United States

Variable parameters Unit Minimum Baseline Maximum Sources
Ash content of HWE willow % 0.2 1.2 2.8 [9]
Willow biomass yielda
 Cropland Mg ha−1 year−1 9.4 11.6 13.8 [17]
 Grassland Mg ha−1 year−1 8.2 10.7 13.6
Ethanol distribution distance km 60 80 100 [18]
Ethanol yield g/g 0.37 0.41 0.51 [5]
HWE Mass removal % 19.9 22.4 26.6 [9]
Leaf nitrogen content % 1.88 2.32 2.78 [17, 40]
Moisture contenta % (wet basis) 37 44 51 [47]
Root to shoot ratio _ 0.46 0.61 0.7 [40]
SOC change
 Cropland Mg C ha−1 year−1 0.19 0.29 0.34 [17, 23, 25]
 Grassland Mg C ha−1 year−1 − 0.43 − 0.29 − 0.19
Storage duration Month 0 3 6 Estimation
Percent of suitable land used % 10 30 100 Estimation
Urea kg N ha−1 80 100 120 [48]
  1. aBiomass yield best fits a logistic probability distribution type and moisture data fits a normal probability distribution. The probability distributions of the other parameters are unknown because of insufficient numbers of data points to run a best fit analysis. We assumed a triangular probability distribution for these variable parameters. The baseline values of biomass yield are the median values across a range of field within the geographic boundary of this analysis, and the minimum and maximum values correspond to 95% confidence interval of these yield data. A minimum of 10% of the total amount of suitable land within the geographic boundary of this analysis is required to supply 700 Mg of willow chips to the biorefinery daily