Biochemical Conversion of Cellulosic Feedstocks James D McMillan National Bioenergy Center National Renewable Energy Laboratory Golden Colorado USA

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Biochemical Conversion of Cellulosic Feedstocks James D McMillan National Bioenergy Center National Renewable Energy Laboratory Golden Colorado USA Powered By Docstoc
					Biochemical Conversion of
  Cellulosic Feedstocks

           James D. McMillan
         National Bioenergy Center
   National Renewable Energy Laboratory
          Golden, Colorado, USA

       Biomass to Chemicals and Fuels:
     Science, Technology and Public Policy
         Rice University, Houston, TX
            September 25-26, 2006
                 Disclaimer and Government License

This work has been authored by Midwest Research Institute (MRI) under
Contract No. DE-AC36-99GO10337 with the U.S. Department of Energy (the
“DOE”). The United States Government (the “Government”) retains and the
publisher, by accepting the work for publication, acknowledges that the
Government retains a non-exclusive, paid-up, irrevocable, worldwide license
to publish or reproduce the published form of this work, or allow others to do
so, for Government purposes.

Neither MRI, the DOE, the Government, nor any other agency thereof, nor
any of their employees, makes any warranty, express or implied, or assumes
any liability or responsibility for the accuracy, completeness, or usefulness of
any information, apparatus, product, or process disclosed, or represents that
its use would not infringe any privately owned rights. Reference herein to any
specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise does not constitute or imply its endorsement,
recommendation, or favoring by the Government or any agency thereof. The
views and opinions of the authors and/or presenters expressed herein do not
necessarily state or reflect those of MRI, the DOE, the Government, or any
agency thereof.
     The Biomass Opportunity:
Large-scale Petroleum Displacement
    and Bioindustry Enablement
 • Move beyond grains to grains plus cellulosic crops
   – Key to achieving substantial petroleum displacement
     and greatly expanding the bioenergy industry

 • USDA/DOE’s “Billion Ton Vision”
  http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf
   – More than 1.3 billion tons of cellulosic biomass (dry basis)
     is sustainably available domestically
   – This amount can provide abundant cheap sugars for
     commodity biofuels (and bioproducts)
      • Sufficient to displace 30% of current gasoline demand
                 Outline

• Composition of Cellulosic Feedstocks
• Biochemical Conversion Routes
• Enzymatic Cellulose Hydrolysis Pathway
• Remaining Technical Barriers/R&D Foci
• Outlook
                      Corn Grain vs. Cellulosics
                                         Corn Stover and Beyond
                                                                                                   SWITCHGRASS




    http://maize.agron.iastate.edu/corngrows.html   http://www.bisonfarm.com/images/fsp-corn.jpg



         GRAIN                                          STOVER                                       POPLAR




http://arnica.csustan.edu/key/corn.jpg
   Composition: Grain vs. Cellulosics
                                  Corn           Corn            Switch-           Poplar
Component                         Grain         Stover            grass
Starch                            72-73           Trace            Trace               0
Cellulose/Hemicellulose           10-12           63-74              60                73
Lignin                               0            14-18              10                21
Other Sugars                        1-2            3-5                6                3
Protein                            8-10            1-3                5                0
Oil/Other Extractives               4-5              2               13                3
Ash                                 1-2            6-8                6               0.5



Total                            96-104         90-110               100              100


Constituent levels can vary by roughly ± 5% dry weight due to environmental and genetic factors
Cellulosic Biomass: Major Constituents
                                    H       C O
                                        3
                                                                                                                                                                           H     C O


Lignin: 15%–25%
                                                                                                                                                                               3
                                    H O
                                                                                                          O C H                                                                 O
                                                                                                                    3
                                                               O                    O                                                                                                                                      O H



 – Complex aromatic structure                                                           O C H
                                                                                                  3
                                                                                                                         O
                                                                                                                                    O C H O C H
                                                                                                                                          3     3

                                                                                                                                                         O H                     O CH
                                                                                                                                                                                           3
                                                                                                                                                                                                      HO
                                                                                                                                                                                                                       O
                                                                                                                                                                                                                                               O O
                                                                                                                                                                                                                                                 H

                                                                                                                                                                                                         O

 – High energy content
                                                                                                                                                                   O                                                         HO
                                             HO                                                                                                                                                          O H
                                                                                                                     O                                                     O H             O                                             O     HO
                                                                                                                              H O                                                                                                 O
                                                                                                                                                                                                                                                          O
                                                                                                                                                                                                                                                        O H

 – Resists biochemical conversion                                                                                            O H                                                           O H                                    O H
                                                                                                                                                                           O H                             O H         O
                                        O C H                                                                                   H           C O
                                                  3                                                                                     3                                                                                           HO
                                                                                                                     O C H
                                                                                                                                    3                                  O                                                                       O    H O
                                                                                                                                                        H O                                                            O H
                                                                                                                                                                                                        O
                                                                                                                                                                                                      O H                                                   H
                                                                                                                                                                                                                                                          O O
                                                                                                                                                                                                                                         O
                                                                   O C H O C H                                                                                                                                                           O H
                                                                         3     3
                                                          O                                                                                              O                                                                    O
                                                                                                                                                                                 H O                               O H                   H O
                                                                                                                    O C H                                O H

Hemicellulose: 23%–32%
                                                                                        O H                                     3             O                                                O     H O                                            O     HO
                                                                                                  O
                                                                                                                                                                                      O                                      O H             O
                                                                                                                                                                                                                 O H
                                                                                                                                                                                                                   O                                              O
                                                                                                                                                                                                                                                                O H
                                                      O                                                       O H                             O H                                     O H                                                    O H
                                                                                                                         O H                                   O H         O                                            O H        O

 – Xylose is the second most
                                                              H O
                                                                                                                                                                                        HO                                                     HO
                                                              O H
                                                                                                                    O                                                                                O                                                    O
                                                                                                  H O                                                                   O H                                  H O                   O H                         HO
                                                               H        C O                                                                                 O
                                                                                                                                                          O H                                                        O
                                                                                                                                                                                                                   O H
                                                                    3                                                                                                                          O                                                    O

   abundant sugar in the biosphere                    O C H
                                                                3
                                                                                                      O
                                                                                                      O H
                                                                                                                                    H O                                O H       O
                                                                                                                                                                                               O H
                                                                                                                                                                                               HO                               O H      O
                                                                                                                                                                                                                                                    O H


                                                                                        O                                                          O     H O                                                 O    H O

 – Polymer of 5- and 6-carbon sugars,                                   O H
                                                                                        O H
                                                                                                               O H          O
                                                                                                                                             O
                                                                                                                                             O H
                                                                                                                                                                   O O
                                                                                                                                                                     H

                                                                                                                                                                           O H
                                                                                                                                                                                 O H

                                                                                                                                                                                       O
                                                                                                                                                                                                   O
                                                                                                                                                                                                   O H
                                                                                                                                                                                                                               H
                                                                                                                                                                                                                             O O
                                                                                                                                                                                                                                         O H




   marginal biochemical feed                  H O
                                                               O
                                                                                                            O
                                                                                                          O H
                                                                                                                            OH
                                                                                                                                              H O
                                                                                                                                                         O     HO
                                                                                                                                                                          H
                                                                                                                                                                        O O
                                                                                                                                                                                       O H
                                                                                                                                                                                                      H O
                                                                                                                                                                                                                   O       HO
                                                                                                                                                   O                                                         O
                                                                                                                                                   O H                                                       OH
                                                  O
                                                                                                                        O H             O                                            O H       O
                                                                                HO                                                                 H O
                                    O             O
                                                                                              O       HO                                                       O     H O


Cellulose: 38%–50%
                                                                                        O                                           O H                 O                                      O H
                                                                                                                      O
                                                                                                                    O H                                                           O
                                                                                                                                                                                O H
                                                                                        O H                                                             O H
                                                              O H         O                                                  O H             O
                                                                                            H O                                                           HO


 – Most abundant form of carbon in                                       O H
                                                                                              O
                                                                                              O H
                                                                                                          O    H O
                                                                                                                         O H
                                                                                                                           O
                                                                                                                                             O H
                                                                                                                                                               O
                                                                                                                                                               OH
                                                                                                                                                                       O       H O




   biosphere
                                                                        O H         O                                                   O H         O
                                                                                              HO
                                                                                                               O     H O
                                                                                O H                   O                                            O H
                                                                                                                                     O
                                                                                                                                    OH

 – Polymer of glucose, good
                                                                                                      O H
                                                                              O H        O
                                                                                                          H O


   biochemical feedstock                                                                O H                             O       H O
                                                                                                               O
                                                                                                               O H
                                                                                    O H           O


                                                                                              O H
                 Outline

• Composition of Cellulosic Feedstocks
 Biochemical Conversion Routes
• Enzymatic Cellulose Hydrolysis Pathway
• Remaining Technical Barriers/R&D Foci
• Outlook
Routes to Biofuels
   Bio/chemical
    Bio/chemical        Ethanol
   transformation
    transformation      from sugars
   of natural
    of natural          Biodiesel from
   compounds
    compounds           renewable oils



                        Traditional
                        chemistry
   Thermal reduction
    Thermal reduction   Fischer-Tropsch
    to “syngas”
     to “syngas”        diesel, gasoline
   (H2,,CO) chemical
    (H2 CO) chemical    Methanol,
   building blocks
    building blocks
                        other alcohols
                        (bio/catalytic)
    The USDOE Biomass Program
Organized Around an Evolving Biorefinery Vision

                                 Biomass as
                                 “The New
                                 Petroleum”—
                                 and beyond:
                                 Source of food,
                                 feed, fiber, and
                                 fuels (and
                                 chemicals)
  Biochemical Conversion Pathways
                                             Biomass
• Hydrolysis/Sugar Fermentation                        Size
                                                       Reduction
                                                                      Dilute
                                                                       Acid
                                                                                           Cellulase
                                                                                           Enzymes
                                                                     Pretreat-
  Categorize based on method for                                      ment


  breaking down cellulose                                              L     S


  – Dilute acid hydrolysis
                                                                                       L                     Ethanol
                                                                                   S
  – Concentrated acid hydrolysis                                                                             Recovery

                                                                   Neutralization/
  – Enzymatic hydrolysis                                            Conditioning Gypsum
                                                                                        Saccharification/
                                                                                          Fermentor           L
                                                                                                                   S
                                                                                                                            Lignin
                                                                                                                           Utilization
     • After using any of a variety of
       different primary fractionation or                                                                   Waste water

       “pretreatment” methods

• Gasification/Synthesis Gas                                                                           Fermentor
                                                                                                                           Ethanol
                                                                                                                          Recovery

  Fermentation                                                                     Clean Up/
                                                                                  Conditioning

  – Thermochemical gasification
                                                                                                         Syngas Fermentation
    followed by fermentative                                           Gasifier
    conversion of (cleaned up)
    syngas
                                            Biomass       Size
                                                        Reduction
                                                                           Syngas Production
Why Emphasize Enzymatic Route?
• Commercial processes based on enzymatic hydrolysis of cellulose
  don’t yet exist, but are believed to offer the best long-term potential
  for minimizing ethanol production costs

                      $0.00
   ΔProduction Cost




                      ($0.10)
     ($/gal EtOH)




                      ($0.20)      ($0.14)
                                                 ($0.19)
                      ($0.30)

                      ($0.40)

                      ($0.50)

                      ($0.60)
                                                             ($0.61)
                      ($0.70)
                                Concentrated   Two Stage     Enzyme
                                    Acid       Dilute Acid
                  Outline

• Composition of Cellulosic Feedstocks
• Biochemical Conversion Routes
 Enzymatic Cellulose Hydrolysis Pathway
• Remaining Technical Barriers/R&D Foci
• Outlook
  Carbohydrate Conversion Steps
 Feedstock
Collection and      Amylases      Hexose Utilizing
                                     Microbe
  Delivery
                                                          STARCH
                 Grain Mashing                         “FUEL & FEED”
                                   Glucose               PROCESS
                  Using Acid,
Pre-processing                      Sugar
                  Jet Cooking,
                                 Fermentation
                 and Enzymes

Thermochemical
 Pretreatment                                            Ethanol and
  Using Acid                     Hexose and Pentose
                                                       Solids Recovery,
                   Cellulases
    or Alkali
                                  Utilizing Microbe     Water Recycle


                  Cellulose         Mixed
 Conditioning     Hydrolysis       Biomass
                    Using           Sugar                 STOVER
                  Enzymes        Fermentation         “FUEL & ENERGY”
                                                         PROCESS
Conversion is Technically Feasible…
   Coarsely milled       Pretreated     Residue
     corn stover           solids        solids




                            Process      Lignin
                         intermediate   coproduct

100 g raw solids (dry)    60 g (dry)    27 g (dry)

…the Challenge is Making it Economical!
Conceptual Stover-to-Ethanol Process
        Feedstock Handling                         Pretreatment           S/L Separation



Corn Stover                              Steam &
                                           Acid                            Liquor

                                   CO2               Enzyme        Lime
         Ethanol
                                                                  Gypsum
                           Steam


                                     Enzymatic Hydrolysis              Conditioning
                                       & Fermentation
Wastewater            Distillation &
Treatment          Ethanol Purification
                                                               Burner/Boiler
        Lignin                                                Turbogenerator
       Residue                                                                      Steam


                                                                                Electricity
Cellulosics Must Compete with Starch
    Corn Grain is King in America!
                                      Comparative Economics
                                      Biomass Program Goal: Market Competitiveness
                           1.4

                           1.2
                                                                              Costs driven by
Relative Production Cost




                           1.0
                                                                 Cap. Depr.   –   Feedstock
                           0.8                                   Fixed        –   Coproduct value


                                                    Total Cost
                                                                              –   Utilities prices
                           0.6                                   Enzymes
                                                                              –   Capital equipment
                           0.4                                   Chemicals        •   Pretreatment
                                                                 Feedstock        •   Enzyme Production
                           0.2                                                    •   Distillation
                                                                 Coproduct        •   Boiler/Combined
                           0.0
                                                                                      Heat and Power
                           -0.2         Enzymatic
                                         Stover
                           -0.4   Corn Dry
                                    Mill
      Opportunities and Challenges
• Lower operating cost
  – Operating cost potentially 20-40% lower processing cellulosics
    (highly feedstock cost dependent)
  – Diversifying feedstock options hedges against rising grain or
    utilities prices


• Higher capital cost
  – $2.5-4.0/annual gal for cellulosics vs. $1.0-1.5 for grain

• Potential for novel higher value coproducts
  – Opportunity: New process streams provide opportunities
  – Challenge: Disparate scales of fuels and coproducts markets
                                        Cellulosic Ethanol Cost Reduction
                                               Progress and Goals
                                        $6.00
                                                                         Corn Stover Feedstock
                                                                                                             Enzyme
Minimum Ethanol Selling Price ($/gal)




                                                         “State of                                           Conversion
                                                                                                             Feedstock
                                                       Technology”                                           Current DOE Cost Targets
                                                        Estimates                                            President's Biofuels Initiative
                                        $5.00                                                                Costs in 2002 Dollars


                                                       Feed $53/ton
                                        $4.00




                                        $3.00




                                        $2.00

                                                                         2005 Yield
                                                                         65 gal/ton

                                        $1.00

                                                                                             Feed $30/ton       Feed $30/ton
                                                                                             Yield 90 gal/ton Yield 94 gal/ton
                                                                                                                     10,000 TPD
                                        $0.00
                                                2000                  2005            2010            2015                           2020
                 Outline

• Composition of Cellulosic Feedstocks
• Biochemical Conversion Routes
• Enzymatic Cellulose Hydrolysis Pathway
 Remaining Technical Barriers/R&D Foci
• Outlook
     Techno-economic Barriers
Directing Research and Development
 • Feedstock Valuation and Delivery
   – Analytical methods/sensors
   – Sustainable supply systems

 • Biomass Recalcitrance to Conversion
   – Pretreatment and enzymatic hydrolysis
   – Pentose and/or mixed sugar fermentation

 • Biorefinery Integration
   – Depolymerization chemistry and process interactions
   – Solids and non-Newtonian slurry handling
1st R&D Barrier: Cell Wall Recalcitrance
• Lignocellulose cell walls
  contain intermeshed
  carbohydrate and lignin
  polymers and other
  minor constituents
  – The major structural
    polymers – cellulose,
    hemicellulose, and
    lignin – exhibit
    differential reactivity to
    thermal, chemical, and
    biological processing
  – By natural design, cell
    wall polysaccharides
    are more difficult to
    break down than
    storage carbohydrates
    like starch
           High Solids Pretreatment Demonstrated
Key to High Sugar Concentrations and Lower Cost
                        Relative Cost = f(Pretreatment Reactor Solids Loading)
                1.15     Parr                       Sunds reactor modifications completed
                        Reactor
                                                       that permit reliable, continuous
                         Limit
                                                    operation at high solids levels (≥ 30%)
Relative MESP



                         <10%
                1.12



                1.08              Achieved
                                   in 2000,                             Base Case
                                  Standard                               Process
                                  Condition                               Target         Achieved
                1.04               in 2001                                                Spring
                                               Standard                                    2003
                                               Condition
                                                in 2002
                1.00                                        Achieved
                                                            in spring         Achieved
                                                              2002           in summer
                                                                                2002
                0.96
                    15%                  20%          25%                  30%             35%

                       Feed Solids Concentration to Pretreatment (wt%)
    Enzyme Costs Have Fallen Sharply
• DOE Subcontracts to Genencor and Novozymes (cost-shared)
   Focus: lower production cost, increase enzyme system efficacy
  – Enzyme cost ($/gallon EtOH) = Prod. Cost ($/kg) x Usage Req. (kg/gallon EtOH)
    Cellulase cost reduced to below $0.20/gal EtOH (by subcontract metric)

                                                         E1 from A. cellulotiticus



                            CBH1 from T. reesei                     +2

                                                                    +1

                                                                    -1

                                                                    -2




                                                              Y82

                                                                         cellodextrin
Enzyme Cost No Longer Showstopper
                                 5.50
                                                                                               0.70
                                 5.00                                                          0.65
                                                                                               0.60




                                                              Cellulase Cost ($/gallon EtOH)
                                 4.50                                                          0.55
                                                                                               0.50
Cellulase Cost ($/gallon EtOH)




                                                                                               0.45
                                 4.00                                                          0.40
                                                                                               0.35
                                                                                               0.30
                                 3.50
                                                                                               0.25
                                                                                               0.20
                                 3.00                                                          0.15
                                                                                               0.10
                                                                                               0.05
                                 2.50                                                          0.00
                                                                                                03/21/03              03/20/04         03/20/05
                                 2.00                                                                                     Date


                                 1.50

                                 1.00

                                 0.50

                                 0.00
                                   01/02/00   01/01/01   01/01/02                                          01/01/03         01/01/04    01/01/05
                                                                                                      Date
Learning How Molecules Move in Biomass
    Through Imaging at Scale of Cell Wall Ultrastructure

             1 mm
              SEM




                                                                                                   Pretreatment
                                                                                                   chemicals and
                                                                                                   enzymes penetrate
                                                                                                   corn plant cell wall
                                                                                                   tissues through
                                                                                                   vessels and pits




Source: M. Himmel et al. (NREL, 2004) in collaboration with Colorado School of Mines EM Facility
             2nd R&D Barrier: Pentosan Utilization
                        100%

                        90%
Carbohydrate Fraction



                        80%

                        70%

                        60%                                   Acetate & Uronics
                                                              Galactan/Mannan
                        50%                                   Xylan/Arabinan
                                                              beta-Glucan
                        40%
                                                              alpha-Glucan
                        30%

                        20%

                        10%

                         0%

                               Corn     Corn Switch- Poplar
                               Grain   Stover grass
                   Cofermentation Pathway in Engineered
              D-Xylose Zymomonas mobilis (putative) D-Glucose
                          EXT                                                                                                     EXT

                          Pentose Metabolism Pathway                                       Entner Doudoroff Pathway
                      XYL Transport                                                                       GLUC Transport

               D-XyloseINT                                                                                            D-GlucoseINT
                                                                                                                               ATP
                                                                                                                        1
                                                                                                     13                       ADP
                14        Xylose isomerase
                                                                                                                      Glucose-6-P
 Xylose
                                                                                                                          2
Utilization    D-Xylulose                                                                                          Gluconolactone-6-P
                         Xylulokinase                                                                                     3
Enzymes         15                                                                                                  6-P-Gluconate
                         ATP
                         ADP           19                                                                                 4
                                                               20                                          2-Keto-3-deoxy-6-P-Gluconate
                 D-Xylulose-5-P             Ribulose-5-P            Ribose-5-P
                                                                                                               5
                                                                                                           Glyceraldehyde-3-P
                        18-1                                    16-3
                                     Transketolase                                                             6
                        18-3                                    16-1                                      1,3-P-Glycerate
                                                                                                                     ADP
                                                                                                              7
 Pentose       Sedoheptulose-7-P                         Glyceraldehyde-3-P
                                                                                                                     ATP
                                                                                                          3-P-Glycerate
Phosphate                                                                                                      8
                                                                                                        2-P-Glycerate
 Pathway                        17      Transaldolase
                                                                                                            9        ADP ATP
Enzymes                                                                                            Phosphoenolpyruvate      Pyruvate
                                                                                                                                 10     11
                                16-2                    18-2
              Erythrose-4-P                                    Fructose-6-P                                                   Acetaldehyde + CO2
                                        Transketolase                                                                                   12
                                                                                                                                      EthanolINT
                       18-1                                            16-1                                            ETOH Transport

                     (1) GK, (2) GPD, (3) PGLS, (4) PGD, (5) KDPGA, (6) GAPD, (7) G3PK, (8) GPM, (9) ENO, (10) PYRK,
                      (11) PYRD, (12) ALD, (13) PGI, (14) XI, (15) XK, (16) TKT, (17) TAL, (18) TKT, (19) RPE, (20) RPI               EthanolEXT
3rd R&D Barrier: Process Integration
                             Amount of cellulose
                            Cellulose crystallinity
                            Available surface area              Enzymatic
  Biomass                Amount and nature of lignin
                                                                 Cellulose
                         Type/amount of hemicellulose
Pretreatment                                                  Saccharification
                                    Biomass
             pH Su




                                                                       a
                                                  Hy ol c nce tima ptim
         A          g              Feedstock
           m an ar




                                                            ra atio s
                                                         sis ntr ion
             ou d co




                                                                   o



                                                               te n
                n c n




                                                   ha r c op e
       ph HM t an ond cen




                                                      oly ce at
                                                 Et ga pH atur

                                                    dr on ntr
         en F d iti tra




                                                               r
           ol an ty on ti




                                                            pe
             ic d pe in on




                                                          m


                                                     n o
               s, f u s g s




                                               Te
                 an rf of re
                   d u r ac q .




                                                   Su
                     ca al id
                       t io , s,
                           ns

                                 Biomass
                                  Sugar
                               Fermentation
                                              Mini-pilot Scale Integrated SSCF
                                             Total solids = 20% (70% v/v liquor)
                                   50       Purchased enzyme at 25 FPU/g cellulose
Concentration or Total CO2 (g/L)

                                                Carbon balance closure = 99%
                                            Pretreated Yellow Poplar (PYP)
                                   40                CPN cellulase
                                               Adapted rDNA Z. mobilis



                                   30                                                            Glucose
                                                                                                 Xylose
                                                                                                 Cellobiose
                                   20                                                            Ethanol
                                                                                                 Total CO2

                                   10


                                   0
                                        0         24       48        72        96    120   144   168       192
                                                                          Time (h)
Intensified Processing Key to High Titers
Example: Glucose Production from Whole Slurry
                                Whole Slurry Total Solids (w/w)
                                      10%     20%        30%
 Glucose Concentration (g/L)


                               175
                                      Whole Slurry
                               150
                                      Total Sugars
                               125                Whole Slurry                Washed
                                                  Total Glucose               Solids
                               100

                                75
                                                              Whole Slurry
                                                              Net Glucose
                                50

                                25
                                                  Approx.
                                                  STR Limit
                                 0
                                     5%     10%       15%          20%       25%       30%   35%
                                              Initial Insoluble Solids (w/w)
High Solids Enzymatic Saccharification
Pretreated corn stover, 45ºC, 20 mg cellulase/g cellulose, 25% initial insoluble solids loading
  Video shows how slurry rheology changes over 7 days of enzymatic cellulose hydrolysis
                 Outline

• Composition of Cellulosic Feedstocks
• Biochemical Conversion Routes
• Enzymatic Cellulose Hydrolysis Pathway
• Remaining Technical Barriers/R&D Foci
 Outlook
                          Outlook
• Major progress being made
  – Compelling operating costs within reach
  – High solids processing promising to decrease capital hurdle
  – Industry investments in R&D reducing commercialization risks

• More needed to achieve market competitiveness,
  especially for more costly feedstocks
  – Sustainable feedstock supply systems must be developed
  – Process(es) must be proved at scale
  – Societal/Environmental benefits must be rigorously validated

• Breakthroughs will spur deployment – key to achieving
  leap forward economics
  –   Overcoming recalcitrance
  –   Robust ethanologens (>10% ethanol on pentoses/mixed sugars)
  –   New value-added commodity coproducts
  –   Supportive legislation/policies`
           More Information
• The National Renewable Energy Laboratory:
  http://www.nrel.gov

• DOE’s Biomass Program:
  http://www.eere.energy.gov/biomass/

• DOE-USDA Biomass R&D Initiative:
  http://www.biomass.govtools.us/

• Alternative Fuels:
  http://www.afdc.doe.gov
               Acknowledgments


• Funding
    – USDOE’s EERE’s Office of the Biomass Program
• Comparative economics from NREL and NREL-USDA joint study
    – USDOE/NREL: Kelly Ibsen, John Jechura, Robert Wallace
    – USDA ARS: Andrew McAloon, Frank Taylor, Winnie Yee
• Enzyme cost reduction progress
    – Genencor, Novozymes, and NREL (each with large teams!)
• High solids enzymatic saccharification (NREL)
    – Jody Farmer, David Hodge, Dan Schell
• Electron micrographs (NREL)
    – Mike Himmel, Todd Vinzant

				
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