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Table 4 Use of autohydrolysis of mixed Southern hardwoods to produce sugar-laden hydrolysate and autohydrolysis residue

From: Integration of pulp and paper technology with bioethanol production

Comparison of autohydrolysis options
Hardwood Pretreatments
  Mixed Southern hardwood Mixed Southern hardwood
2-Stage Autohydrolysis Newsprint Repurpose
  Quantity Cost per unit Quantity Cost per unit
Mixed Southern Hardwood 454,545 $72.18 454,545 $72.18
Annual Ethanol Production, Liters 141,771,687   122,880,735  
Ethanol Yield, Liters per BDt 312   270  
CAPEX Total/per Annual Liter 213,776,300 $1.50 $117,823,560 $0.96
Total Biomass Cost per Liter   $0.25   $0.29
Total Enzyme Cost per Liter   $0.11   $0.12
Total Energy Credit/Cost   $0.00   -0.01
Total Direct Cost per Liter   $0.37   $0.43
Total Indirect Cost per liter   $0.36   $0.33
Total Cash Cost per liter   $0.51   $0.61
Total Cost per liter   $0.73   $0.76
M. E. R,$ per liter   $0.71   $0.73
IRR, 0025   12%   12%
  1. The residue is mechanically refined to improve accessibility to enzymes. The hydrolysate is treated with ion exchange resins to remove acetic acid, and then combined with the residue for enzymatic hydrolysis (see Figure4).