biofuels research at the university of...
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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