Progress and Outlook for Low Cost Pretreatment of Cellulosic Biomass for

Biological Production of Fuels and Chemicals

Bin Yang and Charles E. Wyman

Chemical and Environmental Engineering and

Center for Environmental Research and Technology (CE-CERT)University of California

Workshop on Hydrolysis Route for Cellulosic Ethanol From SugarcaneFebruary 11, 2009Campinas, Brazil

2

Sunlight

Wind

Ocean/hydro

Geothermal

Nuclear

SustainableResources

HumanNeeds

Transportation

PrimaryIntermediates

Biomass

Electricity

Secondary Intermediates

Hydrogen

Organic Fuels

Batteries

Sustainable Alternatives for Transportation

By Lee Lynd, Dartmouth

3

CellulosicBiomass

Low TemperatureCellulosic Conversion:

Acid HydrolysisEnzymatic Hydrolysis

High TemperatureCellulosic Conversion:

Pyrolysis, Liquefaction,Supercritical, Gasification

Catalytic Conversion

in Gas Phase

Catalytic Conversion

in Aqueous Phase

Oil RefiningReactions:Catalytic Cracking,

Hydrotreating

BiofuelsBiochemicals

Reaction Pathways for Biomass Conversion

From George Huber, UMass

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Alternative Fuel Mandates in US

From Energy Independence and Security Act of 2007

5

Biological Processing of Cellulosic Biomass

Biological processing of cellulosic biomass to ethanol and other products offers the high yields vital to economic success Biological processing can take advantage of

the continuing advances in biotechnology to dramatically improve technology and reduce costs

6

Historical and Projected Cellulosic Ethanol Costs

Enzyme Feedstock Conversion

Future goal

0

100

200

300

400

500

600

700

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

Cost reductions to date

NREL Modeled Cost

Min

imum

Eth

anol

Sel

ling

Pric

e (c

ents

/gal

)

7

Stage 2Enzymatichydrolysis

Dissolved sugars, oligomers

Solids: cellulose, hemicellulose,

lignin

Chemicals

Biomass Stage 1 Pretreatment

Dissolved sugars, oligomers, lignin

Residual solids: cellulose,

hemicellulose,lignin

Cellulase enzyme

Stage 3Sugar

fermentation

~33% of cost

~12% of cost

~9% of cost

~18% of cost

Total ~39% of cost

Key Processing Cost Elements

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Pretreatment

Reduce biomass recalcitrance to attack by enzymes

High sugar yields are vital

Heat

Disruption

Disruption of Cellulosic Biomass by Pretreatment

Lignin

Cellulose

Hemicellulose

10

Importance of Pretreatment

Although significant, feedstock costs are low relative to petroleum In addition, feedstock costs are a very low fraction

of final costs compared to other commodity products Pretreatment is the most costly process step: Low yields without pretreatment drive up all

other costs more than amount saved Conversely enhancing yields via improved

pretreatment would reduce all other unit costs Need to reduce pretreatment costs to be

competitive

11

Ethanolrecovery

Enzymatichydrolysis

Sugarfermentation

Hydrolyzateconditioning

Central Role and Pervasive Impact of Pretreatment for Biological Processing

Hydrolyzatefermentation

Enzymeproduction

Biomass production

Harvesting, storage,

size reduction

Residueutilization

Wastetreatment

Pretreatment

Feedstocks Vs. YieldsBiomass

feedstockGlucan

%Xylan

%Theoretical

Ethanol Yield (gal/ton)

Potential Real Ethanol

Yield(gal/ton)

Corn stover 36.1 21.4 105 89

Switchgrass 35.0 21.8 104 88

Sugarcane bagasse 38.6 20.4 108 92

Poplar 43.8 14.9 107 91

Aspen wood 44.8 14.9 109 98

Miscanthus 46.0 19.8 120 102

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Processing Cost Reduction

Increase hydrolysis yield

Halve cellulase loading

Eliminate pretreatment

Consolidated bioprocessing (CBP)

0% 10% 20% 30% 40% 50%

Overcoming the recalcitrance of biomass

3%

13%

22%

41%

Simultaneous C5 & C6 Use

Increased fermentation yield

Increased ethanol titer

Improving production of targeted products

6%

2%

11%

Increased ethanol titer following CBP

6%

Error bars denote two different base cases

Economic Impact of R&D-Driven Improvements

From Nature Biotech. 2008

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Acid

BasePurged with air.0.08 g

CaO/gbiomass

lime4 weeks55Lime

Flow aqueous ammonia at 5 mL/min without presoaking

15ammonia10170ARP

62.5% solids in reactor(60% moisture dry weight basis), 5 minutes at temperature

100Anhydrous ammonia

590AFEX

16% corn residue slurry in water0none15190Controlled pH

Flow hot water at 10mL/min from 4-8 minutes, batch otherwise

0none24200Partial flow pretreatment

Continuously flow just hot water at 10mL/min for 24minutes

0none24200Flowthrough

25% solids concentration during run in batch tubes

0.49Sulfuric acid

20160Dilute acid

Other notesPercent chemical

used

Chemical agent used

Reaction time,

minutes

Temperature, oC

Pretreatment system

Purged with air.0.08 g CaO/g

biomass

lime4 weeks55Lime

Flow aqueous ammonia at 5 mL/min without presoaking

15ammonia10170ARP

62.5% solids in reactor(60% moisture dry weight basis), 5 minutes at temperature

100Anhydrous ammonia

590AFEX

16% corn residue slurry in water0none15190Controlled pH

Flow hot water at 10mL/min from 4-8 minutes, batch otherwise

0none24200Partial flow pretreatment

Continuously flow just hot water at 10mL/min for 24minutes

0none24200Flowthrough

25% solids concentration during run in batch tubes

0.49Sulfuric acid

20160Dilute acid

Other notesPercent chemical

used

Chemical agent used

Reaction time,

minutes

Temperature, oC

Pretreatment system

Key Features of CAFI Leading Pretreatmentsfor Corn Stover

CAFI Feedstock: Corn StoverFrom BioMass AgriProducts, Harlan IA and Kramer Farm, Wray, CO

Component Composition Ethanol yieldwt % gal/ton

Glucan 36.1 62.1Xylan 21.4 37.7Arabinan 3.5 6.2Mannan 1.8 3.1Galactan 2.5 4.3Lignin 29.1Protein ndAcetyl 3.6Ash 1.1Uronic Acids ndExtractives 3.6Total maximum ethanol potential 113.3

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Overall Yields for Corn Stover at 15 FPU/g Glucan

*Cumulative soluble sugars as total/monomers. Single number = just monomers.

Incr

easi

ng p

H

93.9/78.576.717.2/1.859.2/57.556.72.5/0.834.7/21.020.014.7/1.0SO2 Steam

explosion

100.0100.0100.062.362.362.337.737.737.7Maximum

possible

86.8/77.276.610.2/0.658.0/57.357.01.0/0.328.8/19.919.69.2/0.3Lime

89.4/71.671.617.8/056.156.133.3/15.515.517.8/0ARP

94.4/89.194.4/89.159.859.834.6/29.334.6/29.3AFEX

87.2/63.061.925.3/1.156.4/53.152.93.5/0.230.8/9.99.021.8/0.9Controlled

pH

96.6/61.855.8/55.740.8/6.159.7/59.655.24.5/4.436.9/2.20.6/0.536.3/1.7Flowthrough

92.4/91.556.436.0/35.157.153.23.935.3/34.43.232.1/31.2Dilute acid

Combined

totalStage 2Stage 1

Total

glucoseStage 2

Stage

1

Total

xyloseStage 2Stage 1

Total sugars*Glucose yields*Xylose yields*

Pretreatment

system

93.9/78.576.717.2/1.859.2/57.556.72.5/0.834.7/21.020.014.7/1.0SO2 Steam

explosion

100.0100.0100.062.362.362.337.737.737.7Maximum

possible

86.8/77.276.610.2/0.658.0/57.357.01.0/0.328.8/19.919.69.2/0.3Lime

89.4/71.671.617.8/056.156.133.3/15.515.517.8/0ARP

94.4/89.194.4/89.159.859.834.6/29.334.6/29.3AFEX

87.2/63.061.925.3/1.156.4/53.152.93.5/0.230.8/9.99.021.8/0.9Controlled

pH

96.6/61.855.8/55.740.8/6.159.7/59.655.24.5/4.436.9/2.20.6/0.536.3/1.7Flowthrough

92.4/91.556.436.0/35.157.153.23.935.3/34.43.232.1/31.2Dilute acid

Combined

totalStage 2Stage 1

Total

glucoseStage 2

Stage

1

Total

xyloseStage 2Stage 1

Total sugars*Glucose yields*Xylose yields*

Pretreatment

system

CAFI Feedstock: Poplar

Component Composition Ethanol yieldwt % gal/ton

Glucan 43.8 75.4Xylan 14.9 26.1Arabinan 0.6 1.1Mannan 3.9 6.8Galactan 1.0 1.8Lignin 29.1Protein ndAcetyl 3.6Ash 1.1Uronic Acids ndExtractives 3.6Total maximum ethanol potential 111.1

Feedstock: USDA-supplied hybrid poplar (Alexandria, MN) Debarked, chipped, and milled to

pass ¼ inch round screen

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Sugar Yields for CAFI Standard Poplar at 15 FPU/g Glucan

Incr

easi

ng p

H

*Cumulative soluble sugars as total/monomers. Single number = just monomers.

94.3/68.094.3/68.00.076.9/55.076.9/55.

00.017.5/13.017.5/13.00.0

AFEX with

cellulase +

xylanase

95.9/90.774.421.6/16.374.372.02.321.6/16.42.419.2/14.0SO2 Steam

explosion

10010010074.374.374.325.725.725.7Maximum

possible

95.8/89.694.5/89.61.3/0.074.6/72.574.4/72.

50.2/0.021.2/17.120.1/17.11.1/0.0Lime

54.5/44.344.5/44.310.0/0.036.6/36.336.30.4/0.017.7/8.08.2/8.09.6/0.0ARP

52.852.80.039.439.40.013.413.40.0AFEX

73.7/52.251.122.6/1.143.7/42.442.31.4/0.130.0/9.88.821.2/1.0Controlled

pH

82.849.033.864.346.617.718.52.416.1Dilute acid

(Sunds)

Combined

totalStage 2Stage 1

Total

glucoseStage 2Stage 1

Total

xyloseStage 2Stage 1

Total sugar monomers Glucose yieldsXylose yields

Pretreatment

system

94.3/68.094.3/68.00.076.9/55.076.9/55.

00.017.5/13.017.5/13.00.0

AFEX with

cellulase +

xylanase

95.9/90.774.421.6/16.374.372.02.321.6/16.42.419.2/14.0SO2 Steam

explosion

10010010074.374.374.325.725.725.7Maximum

possible

95.8/89.694.5/89.61.3/0.074.6/72.574.4/72.

50.2/0.021.2/17.120.1/17.11.1/0.0Lime

54.5/44.344.5/44.310.0/0.036.6/36.336.30.4/0.017.7/8.08.2/8.09.6/0.0ARP

52.852.80.039.439.40.013.413.40.0AFEX

73.7/52.251.122.6/1.143.7/42.442.31.4/0.130.0/9.88.821.2/1.0Controlled

pH

82.849.033.864.346.617.718.52.416.1Dilute acid

(Sunds)

Combined

totalStage 2Stage 1

Total

glucoseStage 2Stage 1

Total

xyloseStage 2Stage 1

Total sugar monomers Glucose yieldsXylose yields

Pretreatment

system

Projected Costs Virtually the Same with Oligomer Utilization (Black Bars) for Corn Stover

1.00

1.25

1.50

1.75

Dilute Acid Hot Water AFEX ARP Lime

MES

P, $

/gal

EtO

H

w/o Oligomer Credit w/ Oligomer Credit

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Opportunities to Reduce Pretreatment Cost Need to reduce cost from the operation units:

Energy use Costs of chemicals Containment costs Size reduction requirements Prefermentation conditioning

Achieve high yields for multiple crops, sites, ages, harvest times

While increasing yields And limiting inhibitors to bioprocessing Advanced pretreatment processes will pay big dividends Key: understand pretreatment mechanisms and how to

improve yields

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Effect of Flow Rate on Xylan Removal from Corn Stover and Oat Spelt Xylan

0 2 4 6 8 10 120

10

20

30

40

50

60

70

80

90

100

Corn stover/0mL/min

Corn stover/2mL/min

Corn stover/25mL/min

Xylan/0mL/min

Xylan/25mL/min

Perc

ent o

f pot

entia

l tot

al x

ylos

e, %

Time, minutes

Xylan/2mL/min

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Yield of Xylan Oligomers and Total Xylan Recovery in Hydrolysate

Flow rate Yield, % Feedstock mL/min Total

xylan recovery1

DP1 to 30

Long chain

oligomer2

Ratio of shorter chain

to longer chain

oligomer 0 (Batch) 38.1 28.1 10.0 2.8

2 48.2 20.3 27.9 0.7 Corn stover

25 73.3 9.1 64.2 0.1 0 (Batch) 73.1 30.1 43.0 0.7

2 92.1 0.3 91.8 0.003 Oat spelt xylan

25 91.1 0.4 90.8 0.004 1. Total xylan recovery = yield of xylose in hydrolysate+ yield of oligomers in

hydrolysate (xylose equivalent);2. Yield of long chain oligomer (DP>30) = total xylan recovery – yield of DP1∼30.

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Effect of Xylan Removal on Digestibility of Corn Stover for Batch and Flowthrough Reactors

0 20 40 60 80 10010

20

30

40

50

60

70

80

90

100

Uncatalyzed batch tube (160-220C, 5% solid loading) Catalyzed batch tube (160-220C, 5% solid loading, 0.1% acid) Uncatalyzed flowthrough (160-220C, flow rate of 2ml/min) Uncatalyzed flowthrough (160-220C, flow rate of 7.5ml/min) Uncatalyzed flowthrough (160-220C, flow rate of 25ml/min) Catalyzed flowthrough (160-220C, flow rate of 2ml/min) Catalyzed flowthrough (160-220C, flow rate of 7.5ml/min) Catalyzed flowthrough (160-220C, flow rate of 25ml/min)

Enzy

mat

ic di

gest

ibilit

y,%

Xylan removal,%

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Effect of Lignin Removal on Digestibility of Corn Stover for Batch and Flowthrough Reactors

0 10 20 30 40 50 60 70 80 9010

20

30

40

50

60

70

80

90

100

Enzy

mat

ic dig

estib

ility,%

Lignin removal,%

Uncatalyzed batch tube (160-220C, 5% solid loading) Catalyzed batch tube (160-220C, 5% solid loading, 0.1% acid) Uncatalyzed flowthrough (160-220C, flow rate of 2ml/min) Uncatalyzed flowthrough (160-220C, flow rate of 7.5ml/min) Uncatalyzed flowthrough (160-220C, flow rate of 25ml/min) Catalyzed flowthrough (160-220C, flow rate of 2ml/min) Catalyzed flowthrough (160-220C, flow rate of 7.5ml/min) Catalyzed flowthrough (160-220C, flow rate of 25ml/min)

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Role of Lignin in Pretreatment Historically divergent opinions on role of lignin versus

hemicellulose in access of enzymes to cellulose in

pretreated biomass

Our results suggest that lignin must be disrupted to achieve

high enzymatic hydrolysis Hemicellulose removal serves as a marker of lignin disruption but

is not the cause of better digestion

Even better results if remove lignin

Lignin-xylan oligomers and their solubility could have a large effect on the rates and yields of lignocellulosic biomass pretreatment

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Improve the understanding of biomass fractionation, pretreatment, and cellulose hydrolysis to support applications and advances in biomass conversion technologies for production of low cost commodity products

Develop advanced technologies that will dramatically reduce the cost of production

Mission of UCR Ethanol Research

27

Current Research Topics Diesel fuel from biomass – DARPA Effect of different pretreatments on enzymatic hydrolysis

of poplar wood and switchgrass – US DOE Lead Consortium with Auburn, Michigan State, NREL, Purdue,

Texas A&M, U. British Columbia, and Genencor

Pretreatment of cellulosic biomass for BioEnergy Science Center (BESC), $25million/yr DOE Center

Continuous hydrolysis and fermentation – USDA Continuous fermentations of pretreated biomass - NIST Fundamentals of biomass pretreatment – Mascoma

Corporation Evaluation of advanced plants – Mendel Biotechnology Enzyme inhibition by oligomers – Bourns College of

Engineering

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Example Experimental Systems4 ”

Pretreatment tubes Pretreatment reactor Flowthrough Reactor

Pretreatment steam gun Continuous FermentationHTP pretreatment system

Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI)

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Agricultural and Industrial Advisory Board CAFI DOE Project

Quang Nguyen, Abengoa BioenergyJim Doncheck, Arkion Life Sciences Gary Welch, AventinereiMohammed Moniruzzaman, BioEnergy IntlParis Tsobanakis, CargillJames Hettenhaus, CEASteve Thomas, CERESLyman Young, ChevronTexacoMike Knauf, CodexisJulie Friend, DuPontJack Huttner, GenencorDon Johnson, GPC (Retired)Jeff Gross, HerculesPeter Finamore, John DeereGlen Austin, Lallemand Ethanol Technology

Kendall Pye, LignolWei Huang, LS9Jim Flatt, MascomaFarzaneh Teymouri, MBIJames Zhang, MendelRichard Glass, NCGAJames Jia, NorFalco SalesJoel Cherry, NovozymesMark Stowers, PoetRon Reinsfelder, ShellPaul Roessler, Synthetic GenomicsCarmela Bailey, USDADon Riemenschneider, USDA Kevin Gray, VereniumChundakkadu Krishna, Weyerhaeuser

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Alternative Fuels User Facility

The BESC Team: Recently Funded by DOE for $125 Million Over 5 Years

Joint Institute for Biological Sciences

• Oak Ridge National Laboratory• University of Georgia• University of Tennessee• National Renewable Energy Laboratory

• Georgia Tech• Samuel Roberts Noble Foundation • Dartmouth• ArborGeni• Mascoma• Verenium• U California-Riverside• Cornell, Washington State, U Minnesota, NCSU, Brookhaven National Laboratory, Virginia Tech

Complex Carbohydrate Research Center

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BESC - A Highly Integrated Cutting-Edge Research Team

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Closing Thoughts Biology provides a powerful platform for low cost fuels

and chemicals from biomass Can benefit both crop production and conversion

systems The resistance of one biological system (cellulosic

biomass) to the other (biological conversion) requires a pretreatment interface

Advanced pretreatment systems are critical to enhancing yields and lowering costs

Not all pretreatments are equally effective on all feedstocks

Focus on 2 biologies - plants and biological conversion -without integrating their interface – pretreatment – will not significantly lower costs

Rajeev Kumar

Bin Yang

JaclynDeMartini

Michael Studer

Jian Shi

Qing Qing

Simone Brethauer

MirvatEbrik

HeatherMcKenzie

Charles Wyman

Tim Redmond

Taiying Zhang

Acknowledgments Ford Motor Company The BioEnergy Science Center, a U.S. Department of Energy Bioenergy

Research Center supported by the of Biological and Environmental Research Office in the DOE Office of Science

DARPA Mascoma Corporation Mendel Biotechnology National Institute of Standards and Technology, award number

60NANB1D0064 USDA National Research Initiative Competitive Grants Program, contract

2008-35504-04596 US Department of Energy Office of the Biomass Program, contract DE-

FG36-07GO17102 The University of California at Riverside The University of Massachusetts, Amherst Numerous past and present students, coworkers, and partners who make

our research possible35

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Questions???