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Table 2 Summary of process conditions and efficiencies used in current models and other studies

From: Impact of pretreatment and downstream processing technologies on economics and energy in cellulosic ethanol production

  Parameters Dilute Acid Hot Water Dilute Alkali Steam Explosion
   Present Study Laser et al. [30] Aden et al. [19] Kazi et al. [29] Eggeman and Elander[31] Present Study Kazi et al. [29] Eggeman and Elander[31] Present Study Present Study
Biomass Biomass Tall Fescue Switchgrass Corn Stover Corn Stover Corn Stover Tall Fescue Corn Stover Corn Stover Tall Fescue Tall Fescue
Biomass Processing Feedstock Rate (dry Mg/day) 704.5 4535 2000 2000 2000 704.5 2000 2000 704.5 704.5
Pretreatment Temperature (°C) 180 190 190 190 140 180 190 180 180 180
  Pressure (bar) 11 12.3 12.3 11.8 - 11 12.5   11 11
  Residence Time (min) 15 2 2 2 - 15 5 5 15 15
  Solid Loading (%) 20 30 30 29.6 - 20 12.9 13.9 20 30
  Acid/Alkali Concentration (%) 1 1.1 1.1 1.9 1 0 0   1 -
  Cellulose + 0.111 H2O→ 1.111 Glucose (%) 13.04 6.5 7 6.3 8c 0.43 0.32 4.5c 0.29 5
  Xylans + 0.136 H2O → 1.136 Xylose (%) 60.26 85 90 82.5 90.2c 70 2.39 50.8c 0.72 70
  Lignin → Soluble Lignin (%) 5 5 5 10 - 5 5   25 5
  Xylose → 0.64 Furfural + 0.36 H2O (%) 5 5a 5a 10a - 2.5 0a - 0.01 15
  Glucose → 0.7 HMF + 0.3 H2O (%) 5 - - 3b - 2.5 0b   0.01 15
Hydrolysis
and
Fermentation
Bioconversion Method SSCoFd SSFe SSCoF SSCoF - SSCoF SSCoF   SSCoF SSCoF
  Temperature (°C) 35 37 65 (Sacchaarification)
41 (Co-fermentation)
32 - 35 32   35 35
  Enzyme Loading (FPU/g cellulose) 15 15 12 18f 15 15 18f 15 15 15
  Time (Saccharification + Fermentation) (days) 5 7 3 (1.5 + 1.5) 7 (5+2) - 5 7 (5+2)   5 5
  Cellulose + 0.111 H2O→ 1.111 Glucose 79 80 90 91.09 83.8c 78.5 89.97 90c 84.75 70
  Xylans + 0.136 H2O → 1.136 Xylose (%) 80 80 - 57.13 55.1c 80 56.6 64.63c 80 80
  Glucose → 0.489 CO2 + 0.511 Ethanol (%) 95 90 95 95   95 95   95 95
  Xylose → 0.489 CO2 + 0.511 Ethanol (%) 70 90 85 75.6   70 75.6   70 70
  Cellulase → 0.1 Protein Soluble + 0.9 water (%) 99 - - - - 99 - - 99 99
Ethanol Recovery Ethanol Recovery (%) 98.76 98.8 98.9 - - 98.76 - - 98.76 98.76
  1. a Percentage conversion of xylans to furfural
  2. b Percentage conversion of cellulose to furfural
  3. c The efficiencies are based on cumulative sugars (oligomers+monomers)
  4. d SSCoF - Simultaneous saccharification and Co-fermentation
  5. e SSF - Simultaneous saccharification and fermentation
  6. f 31.3 mg protein/g cellulose (600 FPU/g protein)