|
| Parameter | Value | Source |
|
| Cellulosic ethanol facility assumptions |
| Cellulosic ethanol facility capacity | 61 million US gallons/year | Humbird et al., 2011 [49] |
| Cellulosic feedstock | 700,000 metric tonnes (dry) corn stover per year, 2,000 metric tonnes/day | Humbird et al., 2011 [49] |
| Land area required for corn stover feedstock | 2,034,000 hectares/year | Humbird et al., 2011 [49] |
| Annual operating hours | 8,410 hours/year | Humbird et al., 2011 [49] |
| Conversion | 87 gallons ethanol/metric tonne corn stover @76% conversion | Humbird et al., 2011 [49] |
| Enzyme loading | 20 mg enzyme “protein mixture” per gram cellulose in feedstock (2% wt/wt) | Humbird et al., 2011 [49] |
| Enzyme mixture required | 4,100,000 enzyme “protein mixture” | Humbird et al., 2011 [49] |
| Cellulase enzyme required | 2,870,000 kg/year | About 2% higher than in Klein-Marcuschamer et al., 2012 [16] |
| Cellulase in enzyme mixture | 70.0% total soluble protein | Calculated from above |
|
| Base case tobacco agronomic and cellulase enzyme production assumptions |
| Base case tobacco biomass production | 130 metric tonne fresh weight (FW)/ha year | |
Mass of a full grown tobacco plant growth
at high density | 1.0 kg fresh weight (FW)/plant | |
| Number of plants per hectare | 130,000 plants/hectare | Calculated |
| Tobacco seed cost | $0.001/seed | |
| Tobacco growth cycle | 82 days from seed to induction, harvest at 7 days after induction spray | |
| Tobacco planting season (US Midwest/South) | Late March to late October | |
| Land reuse during growing season | Based on a total of 127 plant batches per year, land recycling can start with batch 94, so land requirement is only 0.74 of that required if no land was reused | Calculated |
Tobacco production cost
(labor and machinery for seeding, harvesting) | $1,000/hectare | |
| Number of tobacco batches per year | 127 batches/year | Calculated |
| Cellulase expression level | 4 g cellulase/kg FW tobacco at 7 days after induction, with 2 applications of ethanol induction solution | Werner et al., 2011 [7] |
| Land area required | 5,519 hectares/year | Calculated |
Tobacco land area required as a fraction
of corn stover land area required | 0.27% | Calculated |
| Ethanol induction | Foliar application of aqueous solution of 2.5% (v/v) ethanol, 2 applications using ground irrigation/sprinklers (central pivot, traveler, or side roll), at 500 L/hectare | |
| Cost of ethanol for induction | $0.73/kg | Humbird et al., 2011 [49] |
Percentage of ethanol drawn off
from biorefinery for induction | 0.12% | Calculated |
Capital cost of ethanol spray
irrigation system | $2,223/hectare | http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs141p2_023892.pdf |
Annual operating cost of ethanol spray
irrigation system | $988/hectare year | http://www.caswcd.org/Irrigation%20guide/Sec7.pdf |
|
| Base case assumptions for plant-based cellulase production facility |
| Construction period | 12 months | Klein-Marcuschamer et al., 2012 [16] |
| Start-up period | 18 months | Klein-Marcuschamer et al., 2012 [16] |
| Project lifetime | 25 years | Klein-Marcuschamer et al., 2012 [16] |
| Income tax rate | 40% | Klein-Marcuschamer et al., 2012 [16] |
| Working capital | 30 days of labor, raw materials, utilities, waste | Klein-Marcuschamer et al., 2012 [16] |
| Start-up cost | 5% direct fixed capital investment, not depreciable | Klein-Marcuschamer et al., 2012 [16] |
| Depreciation | Straight line over 10 years, salvage value 5% direct fixed capital | Klein-Marcuschamer et al., 2012 [16] |
| Unlisted equipment | 5% of the major purchased listed equipment | Klein-Marcuschamer et al., 2012 [16] |
|
