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

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

Variable parameters	Unit		Minimum		Baseline		Maximum		Sources
Ash content of HWE willow	%		0.2		1.2		2.8		[9]
Willow biomass yield^a
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		[17]
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 content^a	% (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		[17, 23, 25]
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]

^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

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