Enzyme SugarEthanol Platform Project

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Enzyme Sugar-Ethanol Platform Project
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Project Goal

• Objective Develop and demonstrate economical
  bioethanol technology based on enzymatic
  cellulose hydrolysis
• Feedstock Constraint Develop the technology for
  an abundant biomass resource that can support
  production of at least 3 billion gallons of
  ethanol per year

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Approach

• Select corn stover as feedstock
• Most abundant, concentrated domestic biomass
  resource
• Potential to leverage existing corn harvesting
  and processing (esp. to produce fuel ethanol)
  infrastructure and bridge industrial contacts
• Utilize low cost enzymes now being developed
• Genencor International and Novozymes Biotech Inc.
  are leading enzyme development work through
  cost-shared subcontracts from the USDOE. Lower
  cost enzymes are anticipated in 2003-2004.
• Demonstrate compelling process economics
• Validate improved process performance and
  identify potentially attractive commercialization
  scenarios.

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Project Scope
NREL-led Development
Industry-led Commercialization
Process Development
Detailed Investigation
Prelim. Studies
Testing and Validation
Commercial Launch
Stage 1
Stage 3
Stage 2
Stage 4
Stage 5
Gov. Univ. Corp. RD
Industry-led deployment
Increasing Cost Industrial Involvement
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Strategic Fit

• The project demonstrates enabling technology for
  a lignocellulose-based biorefinery
• The project focuses on the core steps needed to
  produce sugars, fractionated lignin, and ethanol
• Industry is focusing on the application of this
  technology to make new products

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External Drivers or Showstoppers

• Price of Oil and Gasoline (Transportation Fuels)
• Global supply and demand issue
• Contingent on fuel standards and energy policy
• Price and Availability of Starch (Grain) Ethanol
• Existence of renewable fuel standard
• Markets for starch ethanol co-products
• Price and Availability of Corn Stover
• How much can be removed and what does it cost?
• What infrastructure needed for collection,
  storage and delivery?
• Are there alternative markets that will out
  compete ethanol?
• Environmental Regulations and Policies
• Greenhouse gas mitigation, carbon tax, etc.

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Simplified Process Schematic
Steam Acid
Enzyme
Feed Handling
Fermentation
Pretreatment
Corn Stover
Hydrolyzate
Broth
Recycle Water
Recycle Condensate
Waste Water
Solids
S/L Sep
Liquor
Conditioning
Distillation StillageTreatment
Steam
Waste Water Treatment
Waste Water
Waste Water
Syrup
Ethanol
Biogas Sludge
S/L Sep
Cake
Steam
Utilities
Burner/Boiler Turbogenerator
Storage
Electricity
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Relative Cost Contribution by Area
Capital Recovery Charge
Raw Materials
Process Electricity
Grid Electricity
Total Plant Electricity
Fixed Costs
33
Biomass Feedstock
5
Feed Handling
18
Pretreatment / Conditioning
SSCF
12
(after 10x cost reduction)
Cellulase
9
Distillation and Solids
10
Recovery
Wastewater Treatment
4
4
Boiler/Turbogenerator
Utilities
4
Storage
1
(0.30)
(0.20)
(0.10)
-
0.10
0.20
0.30
0.40
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Process Economics

• Production costs dominated by
• Feedstock
• Enzymes - cellulases
• Capital equipment throughout the plant
• The focus of the project is to work closely with
  USDOE, ORNL, USDA, and others, to decrease these
  key cost factors.

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Key Cost Reduction Strategies

• Minimize feedstock cost
• Work with ORNL, USDA, and others to reduce the
  cost of corn stover by developing policies and
  infrastructure for efficient collection, storage
  and delivery
• Minimize enzyme cost
• Exploit anticipated thermo-stability of lower
  cost enzymes being developed by Genencor and
  Novozymes to reduce enzyme and capital costs for
  process
• Reduce processing plant capital cost
• Demonstrate improved integrated process
  performance
• Use process engineering techno-economic models to
  explore potential benefits of co-location and
  co-products

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Market Goals

• The project targets achieving a commercial
  production cost of 1.10 per gallon by 2010
• This target is based on a combination of
  technical conversion process performance goals
  and market considerations
• The market for ethanol is driven by refinery
  demand for ethanol as a gasoline blend stock

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Ethanol Value-Demand Curve

• Oak Ridge National Labs linear programming model
  for a generic oil refinery used to estimate
  ethanol value as a function of demand (usage)
• Results quantify how the value of ethanol
  decreases as more of it is used

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Refiner Ethanol Demand Curve
Reference conditions
Higher ethanol demand scenario
From G. Hadder (ORNL, 1999)
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Demand Curve Findings

• At 1.10 per gallon, refiners can afford to use
  1-5 billion gallons per year of ethanol,
  depending on the future price of petroleum
• This estimate does not include the effect of a
  tax incentives
• If the tax incentive continues at 0.50 per
  gallon ethanol, refiners can afford to use 10-11
  billion gallons per year

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Possible Process Scenario
Feedstock Handling
Pretreatment
S/L Separation
Steam Acid
Corn Stover
Solids
Liquor
Lime
CO2
Enzyme
Ethanol
Gypsum
Steam
Conditioning
Saccharification Fermentation
Wastewater Treatment
Distillation Ethanol Purification
Burner/Boiler Turbogenerator
Lignin Residue
Steam
Electricity
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Feedstock Corn Stover
Composition is average of 5 stover pretreatment
runs at NREL
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Feedstock Corn Stover

• Rationale for data
• Feedstock Cost
• Walsh, et.al. (ORNL)
• Demonstrated at Harlan, IA
• Feedstock Composition
• Averaged stover data (NREL)
• Research underway to improve analysis methods and
  understand major sources of compositional variance

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Feedstock Corn Stover
Large Cost Impact
Feedstock Cost Impact
1.50
1.48
50 / BDT
1.28
0.65/gal
35 / BDT
1.00
0.83
Minimum Ethanol Selling Price (/gal etoh)
0 / BDT
0.50
0.00
Process Case
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Feedstock Handling

• Brings biomass into facility
• Prepares biomass for pretreatment
• Subcontract work to develop less expensive
  handling systems

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Pretreatment - Example

• Converts hemicellulose to monomeric sugars
• Makes cellulose more susceptible to enzymatic
  hydrolysis

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Pretreatment - Example

• Converts hemicellulose to monomeric sugars
• Makes cellulose more susceptible to enzymatic
  hydrolysis

• Rationale for Data
• Corn stover steam gun expts
• Hot wash process expts
• Prior research on hardwood
• feedstocks

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Pretreatment - Example
Reactor Solids Cost Impact
Prehydrolysis Solids Concentration Sensitivity
1.50
1.45
1.40
1.35
Minimum Ethanol Selling Price (/gal)
1.30
1.25
1.20
10
15
20
25
30
35
40
Prehydrolysis Solids Concentration inside Reactor
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Pretreatment - Example
Xylose Yield Cost Impact
Xylose Yield Cost Impact
1.50
1.50
50 xylose
0.27/gal
85 xylose
1.28
1.23
95 xylose
1.00
Minimum Ethanol Selling Price (/gal etoh)
0.50
0.00
Process Case
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Solid/Liquid Separation

• Separate pretreated solids from liquor
• Countercurrent hot water wash increases enzymatic
  digestibility and solubilizes recoverable lignin

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Solid/Liquid Separation

• Separation of pretreatment solids from liquor
• Countercurrent hot water wash increases enzymatic
  digestibility and solubilizes recoverable lignin

• Rationale for Data
• Lower acetylation of corn stover hemicellulose
  means IX not needed to reduce acetic acid levels
• Hot wash process expts
• Harris subcontract
• Working towards pilot scale demonstration at NREL

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Solid/Liquid Separation
Cost Impact
Conditioning Sensitivity
1.50
1.45
1.40
Minimum Ethanol Selling Price (/gal
1.35
etoh)
0.08 / gal
1.30
1.25
1.20
OL only
IX / OL
Process Case
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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

• Rationale for Data
• Enzyme Cost is 10x-reduction from
  Glassner-Hettenhaus parameters
• 10x-reduction is goal of enzyme subcontracts
• Hybrid design advantageous for more
  thermotolerant enzyme system

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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

• Rationale for Data
• Previous work based on conversion of hardwood
  hydrolyzates using Z. mobilis
• Nutrients
• Strain improvements
• 2nd Gen. ethanologen projects at NREL
• Literature search

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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

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Saccharification Fermentation

• Enzymatic hydrolysis of cellulose to glucose
• Microbial conversion of sugars to ethanol

• Rationale for Data
• Initial work based on glucose and xylose
  cofermenting Z. mobilis
• Improved strains constructed with broader pentose
  and hexose substrate ranges
• rDNA yeast
• Ingram et al. constructs

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Saccharification Fermentation
Enzyme Cost Impacts
Enzyme Cost Impact
2.24
1.07 / gal
2.00
1.01/gal
.50 / gal
1.67
1.50
0.11 / gal
1.28
1.23
Minimum Ethanol Selling Price (/gal etoh)
0.06 / gal
1.00
0.50
0.00
Process Case
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Saccharification Fermentation
Cost Impacts
Fermentation Residence Time Cost Impact
1.50
1.45
1.40
Minimum Ethanol Selling Price (/gal etoh)
1.35
1.32
7 days
1.30
0.07/gal
1.28
3.5 days
1.25
1.25
1 day
1.20
Process Case
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Saccharification Fermentation
Cost Impacts
Fermentation Yield Cost Impact
2.40
70
2.10
Minimum Ethanol Selling Price (/gal)
92
1.80
1.50
95
1.33
1.28
1.23
1.20
glucose only
add 85 xylose
add 85 arabinose
all other sugars
85
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Saccharification Fermentation
Cost Impact
Contamination 5 ? 7 equates to 0.02/gal
increase
Nutrient Cost 0.035/gal 89 CSL, 11 DAP
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Distillation Ethanol Purification

• Separation of ethanol and CO2 from beer

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Wastewater Treatment

• Anaerobic and aerobic treatment
• Reduce Biochemical Oxygen Demand (BOD)
• Recycle water

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Burner/Boiler/Turbogenerator

• Biomass boiler generates steam from lignin
  residue
• Excess electricity from generator sold to power
  grid (0.04/kWh credit)
• High capital cost area

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Current Status

• Completing Stage 2
• Compelling scenario identification
• Technology selection
• Stage 3 plan development
• Next step Gate 3 review
• Planned for January 2002

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Conversion-relatedCost Reduction Opportunities

• Stage 2 technology selection focus
• Is a better pretreatment technology available?
• Higher yields, lower capital or operating costs
• Is a better fermentation strain available?
• Broader sugar utilization range, higher ethanol
  yields, better compatibility with enzyme
• Stage 3 technology improvement focus
• Are better cellulases available and how do they
  benefit integrated process economics?

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Technology Selection

• Tiered screening approach being applied to ensure
  best options will be studied in Stage 3
• 1st screen Efficacy
• 2nd screen Readiness and availability
• Stage 2 focus
• Pretreatment technology
• Fermentation strain

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Co-location-relatedCost Reduction Opportunities

• Better feedstock price
• Proximity to transportation
• Farmer cooperative
• Reduce capital cost
• Utilize existing utilities and processing
  infrastructure within site constraints

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Cost Reduction Strategies, cont.

• Reduce conversion plant capital cost
• co-locate into a dry mill expansion
• co-locate with a coal-fired power plant
• co-locate with both a dry mill and power plant
• Reduce capital cost through better financing
• Loan guarantee?
• City/county/state/federal support or tax benefits?

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Cost Reduction through Co-products

• New process case potentially enables sugar
  platform and lignin platform co-products
• Value-added co-products can increase upside of
  process commercialization and mitigate overall
  risk
• While we can explore the possibilities,
  development of prospective co-products must be
  led by industry!

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Potential Bioethanol Co-products
Hemicellulose Hydrolyzate (Xylose)
Cell Mass, Enzymes (Protein, etc.)
Process Residue Liquids
Cellulose Hydrolyzate (Glucose)
1o Enzymatic Cellulose Hydrolysis
Pretreatment Hemicellulose Hydrolysis
2o Enzymatic Hydrolysis Fermentation
Ethanol Recovery Purification
EtOH
Biomass
Process Residue Solids
Soluble Lignin (Low/Medium MW Phenolics)
Insoluble Lignin (High MW Phenolics)
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Sugar Lignin Platform Biorefinery
Lignin Product(s)
Recovered Lignin
Purification Drying of Lignin Product(s)
Renewable Biomass Feedstock
Catalyst Steam, Acid, Enzyme, etc.)
Water
Steam
Unrecovered Lignin
Sugar Product(s)
Sugar-rich Hydrolyzate
Concentration Purification of Sugar Product(s)
Feedstock Handling
Biomass Fractionation
Water
Steam
Waste Water
Recycle Water
Unrecovered Sugars
Hydrolyzate Residual Solids
Fuel Ethanol
Ethanol Production Recovery
Waste Water Treatment
Make-up Water
Waste Water
Biogas Sludge
Residual Solids Syrup
Steam
Unrecovered Lignin
Power Production (Turbogenerator)
Electricity
Steam Generation
Steam