Sweet Sorghum Ethanol Economics

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					Sweet Sorghum Ethanol Economics

               Rodney B. Holcomb
            Oklahoma State University
       Department of Agricultural Economics
     Robert M. Kerr Food & Ag Products Center
Primary Economic Issues
 Crop production
   Input costs
   Tons per acre
   Sugar content
 Ethanol production
   Juice extraction
   Fermentation
   Distillation
 Co-product handling
   Bagasse
   Vinasse
Crop Production Economics
 Sweet sorghum is highly adaptable, high-sugar varieties known
    Dale and Topper
 Staggered plantings necessary for ethanol production facility
 Crop production budgets
    See Dr. Chad Gosney, OSU
    Mississippi State, Kentucky, Purdue, Kerr Center, etc.
 Yields from test plots vary greatly by location, variety, and dryland
  vs. irrigated
    Less than 15 wet tons/acre to more than 45 wet tons/acre
 Sugar content of juice expected to be between 15%-19%
 Harvest options
    Billet harvester (similar to sugarcane or large-scale sorghum syrup)
    In-field harvester with press capabilities (experimental)
Ethanol Production – Juice Extraction
 Twin screw press
   Least capital input, simplest operation
Ethanol Production – Juice Extraction
 Roller drum mill (i.e. the sugarcane method)
   Hammer mill used to shred billets, open up plant cells
   Juice and hot water circulated to leach out soluble sugars
Ethanol Production – Juice Extraction
 Diffuser (i.e. the sugar beet method)
   Water “percolates” through shredded sorghum, 110-170 feet
   Bagasse must be de-watered with a press
Ethanol Production - Fermentation
 Simple and straight-forward process
 No complex starches to break down prior to fermentation
 The essentials
   Holding tanks and pumps
   Brewer’s yeast
 Greatest economic concern is related to time
   Billets lose sugar content if stored longer than a few hours
   Other microorganisms will make use of the sugar if the yeast
    isn’t added promptly to the juice
 Fermentation takes only a few days, liquid is relatively stable
Ethanol Production - Distillation
 Getting to a fuel-grade product is an issue
   Capital costs for such a distillation system
     Modular systems adopted from grain-based ethanol production
     Pervap membrane system (azeotrope to fuel-grade ethanol)
   Utility and space requirements to operate a distillation system
   Use of an adulterant (regulatory issue)
 Ethanol output per acre of sweet sorghum is highly variable
   120-160 gallons of juice/wet ton of sorghum billets
   11-14 gallons of ethanol per wet ton of sweet sorghum
   330-420 gallons/acre, assuming a 30 wet ton/acre yield
Co-Products – Bagasse and Vinasse
 Bagasse (approx. 650 lbs. per wet ton)
   Crushed/shredded billets, approx. 50-55% moisture content
   Silage potential
     Excellent roughage with supplementation, low protein
     Can flood the market for a given area if too much made available
   Co-generation potential – burn it
     Have to be big enough to justify the capital outlay
     Environmental issues – air emissions and ash disposal
   Cellulosic ethanol production (site-specific)
 Vinasse (approx. 100-120 gal/wet ton)
   Irrigated onto fields (some fertilizer benefit)
   Dehydrated for feed or fertilizer use
Sweet Sorghum Ethanol Template