Biofuels Research at the University of...

Biofuels Research at the University of Washington

Rick Gustafson

Paper Science & Engineering

College of Forest Resource

University of Washington15 July 2008

UW biofuels research agenda

Vision: Cost effective cellulosic transportation fuels

•Use mixed biomass sources•With good process yields

•Profitable at moderate economies of scale

•Co-produce fuels and high value products

•Commodity Chemicals•Polymers•Pulp Fibers

UW research initiatives – three examples

•High-throughput screening process for evaluation of lignocellulosic biomass

•Use of membranes to recover hemicellulose from aqueous streams

•Ethanol from Municipal solid waste (MSW)

High-throughput screening process for evaluation of lignocellulosic biomass

4

Fractionation

BioethanolBiodiesel

Biobutanol

BiopolymersBiochemicals

Hydrogen

BiomethanolBiogas

Bio-oil

XylitolBio-adhesives

5

Lignocellulosic ethanol platform

Raw biomass

Pretreated solids Pretreated liquid

Fermentation

Glucose

Ethanol

Pretreatment

Lignin

Enzymatic hydrolysis

LigninCelluloseHemicellulose

GlucoseOther sugars

Extractives, ash, etc

Proposed research

High throughput screening of multiple biomass types

Experimental method development

FermentationEnzymatic hydrolysis

LigninCelluloseHemicellulose

GlucoseOther sugars

Extractives, ash, etc

Analytical method development

6Ethanol

Research objectives

7

Fractionation

versus

Conventional Micro

Experimental

Flask scale (125ml) 96 wells (0.3 ml/well)

Analytical

HPLC, GC, wet chemistry

RamanNear IR

8

Method development

High throughput hydrolysis

9

Shaker

Handsheet

Pretreated substrate

Berlin et al., 2006Analysis

Analytical requirements

Components to be measured:

Starting biomassCellulose, hemicellulose, lignin

Pretreated substratesSolids: Cellulose, hemicellulose, lignin

Liquid: Glucose, hemicellulosic sugars, inhibitors

10

Analytical requirements

HydrolysisConversion of cellulose to glucose over time

FermentationConversion of glucose to ethanol over timeConsumption of inhibitorsProduction of by-products

Time

Glu

cose

Time By-

prod

ucts

E

than

ol

Glu

cose

11

Analytical techniques

Raman spectroscopyShown to be effective to measure complex mixtures of carbohydrates and other compounds

Near-IR spectroscopyCan be effectively used to measure lignin

Single fiber analyzerMeasure particle characteristics and lignin content

12

Potential applications

Existing bioethanol plantsOver 130 in US (all corn-based)Require means to monitor glucose and ethanol levels in real time during hydrolysis and fermentation

Enzyme developersHigh consistency solids hydrolysisImproved conversion efficiency

Fermentative organism developmentBioengineering for pentose fermentationIncreased temperature tolerance

13

Novel Membranes for Separation and Concentration in Lignocellosic Biorefinery

Power Export – 20 GWor New ProductsO2

PulpPaper

Steam,Power &

Chemicals

BL GasifierWood Residual

GasifierCombined

Cycle SystemProcess to

manufactureLiquid Fuels and

Chemicals

Black Liquor& Residuals

Manufacturing

Liquid FuelsChemicalsPolymers

Powerhouse of the Future

Syngas66 x 106 MT CO2

Extract Hemicelluloses

new products chemicals polymers

CellulosicBiomass

Hemicellulose Extraction

U.S. Kraft pulp mills process roughly 25 million tons of hemicellulose each year

Hemicellulose Ethanol

25 million tons 2 billion gallons

Current US ethanol production is about

7 billion gallons

Hemicellulose Extraction

Hot water extraction – Hardwoods & wheat strawDilute acid extraction – SoftwoodsAlkaline peroxide treatment – Wheat straw

Extraction Hemicellulose from Biomass

Extractives

Lignin

Hemicelluloses

Water

97% water

Composition of Extraction Liquor

Biopolymer Concentration

Removal of Water

2% Hemicellulose 20% Hemicellulose

Membrane SeparationNon-volatile ComponentsLower energy

2/3 – 1/2 that of evaporation

Remove inhibitors as well as water Potential for foulingHigh capital cost

Research Objectives

Assess and optimize membrane separation on biorefinery streams

Process synthetic and commercial process streams

Assess variables in membrane experimentsMembrane pore sizeProcess parameters

Develop methods to characterize and rapidly assess membrane performance

Real time compositional analysis ofbiorefinery process streams.

Use flexible sampling and sensorplatform developed by CPAC

Approach

Membrane Pore Size Screening

Sugar Recovery

Feed Volume:4 ml

Feed Volume:3 liter

Feed Volume:500 ml

Process Optimization

Materials

NaOH (% on O.D.) 10Peroxide (% on O.D.) 5Temperature (oC) 57Time (hr) 2

Synthetic process streamComposition: Beechwood xylose (>90% xylose residues)Concentration: 1.0%Molecular Weight of Xylan: ~8,000 Dalton

Commercial streamSpecies: Wheat StrawExtraction conditions:

Schematic for Dead End Filtration

Syringe pump

Holder with disc membrane

Filtrate

Syringe

Xylan Dead End Filtration Results

0

20

40

60

80

100

1 3 5 10 30 50 100 300

Membrane MWCO (KDa)

Xyla

n re

tent

ion

(%)

Black Liquor Dead End Filtration Results

0

20

40

60

80

100

1 3 5 10 30 50 100 300

Membrane MWCO (kDa)

Solid

reco

very

(%)

0

1

2

3

4

5

6

7

Filtr

atio

n Ti

me

(hrs

)

Peristaltic Pump

Feed Flow

Screw Clamp

Pressure Gauge

Retentate Flow

Filtrate Flow

Feed

Vent Retentate

Filtrate

Minimate TFF Capsule

Schematic for Minimate TFF System

Ambient Temperature

Pressure: 0~2 bar

Filtration stopped when 50% of feed is in filtrate

5K and 10K membranes

Pictures from Pall.com

Total Sugar Conc. in Filtrate & Retentate

0

20

40

60

80

100

120

Arabinose Galactose Glucose Xylose Mannose

Perc

enta

ge o

f Fee

d (%

)

1.0 bar Filtrate

1.0 bar Retentate

0.5 bar Filtrate

0.5 bar Retentate

Schematic for Pilot Unit System

Picture from Pall.com

1. Feed tank2. Recirculation pump3. Membralox T1-70

module4. BF3 backpulse device

Total Sugar Conc. in Filtrate & Retentate

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Arabinose Galactose Glucose Xylose Mannose

Suga

r Fra

ctio

n R

atio

(%)

2.0 bar Filtrate2.0 bar Retentate1.5 bar Filtrate1.5 bar Retentate1.0 bar Filtrate1.0 bar Retentate

Proposed Research

Optimize membrane operationPilot Unit SystemInvestigate separation performance of ceramic membranes

10k and 5k membranes

Process variables TemperaturePressureBackflushing time and frequency

Goal is to optimize flux of filtrate

Municipal Solid Waste

Municipal Solid Waste

Mixed Waste Paper Synthetic GarbageYard Waste

LOTS OF CELLULOSE

CelluloseHemicellulose

EthanolSugars

LigninPretreatments Hydrolysis Fermentation

Bioconversion of mixed paper to ethanol (2)

Pretreatments for mixed paper

Hydropulping (30min)

Mixed paper

Deinking (20min)

Screening

Chemical composition (cellulose, hemicellulose, lignin, and ash) + enzymatic hydrolysis

Compositional analysis of mixed paper

Ara (%)

Gal(%)

Cell(%)

Xyl(%)

Man(%)

Ash(%)

Lignin (%)

Hydropulping 0.9 0.8 62.7 8.9 4.3 10.2 10.2

Deinking 0.9 0.8 71.5 9.6 4.6 5.8 16.7

Deinking+Screening

0.9 0.8 78.3 10.3 5.3 2.2 12.2

Foam rejects 1.0 0.9 55.1 7.6 3.6 21.3 20.5

Enzymatic hydrolysis

Pretreated substrate Flasks Sugar analysisHPLC

Enzymatic hydrolysis-conversions

Glucoseg/L

Cellulose to glucose conversion

(%)

Hydropulping 3.4 27.0

Deinking 4.4 30.8

Deinking+Screening

2.9 18.5

Foam rejects 1.3 11.8

LCA analysis: Base Scenario (current waste management regime)

LCA analysis: Alternative Scenario

Other UW biofuels projects

• Novel yeasts for fermentation and xylitol production• Production of bioethanol from various raw materials

sources using steam explosion pretreatment•Switchgrass•Sugar cane•Giant reed•Hybrid poplar

• Hybrid process to produce ethanol and glycols from cellulosic biomass

• Genetic modification of biomass for biofuels production• Co-production of pulp and bioethanol