Cellulosic Ethanol 101

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Cellulosic Ethanol 101

• Tom Richard
• Department of Agricultural and Biological
  Engineering
• Penn State University
• www.bioenergy.psu.edu

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Biomass Energy Alternatives
Sugar, starch now Lignocellulose? Coming soon
Mature
Semi-mature
3
US Biomass inventory 1.3 billion tons
Wheat straw
Corn stover
6.1
Soy
19.9
6.2
Crop residues
7.6
Grains
5.2
Manure
4.1
Urban waste
2.9
Perennial crops
35.2
Forest
12.8
From Billion ton Vision, DOE USDA 2005
(projections to 2030)
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Ethanol Production Today
BRAZIL
sugarcane
(sucrose)
Sugars
ethanol
extract
ferment
USA
(starch)
Sugars
ethanol
Hydrolyze(enzymes)
ferment
Brazil and the US are the leaders in ethanol fuel
production They use the easy way to make
ethanol.
Cosgrove, 2006
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Chemical structure of starch
STARCH
http//www.ucmp.berkeley.edu/monocots/corngrainls.
jpg
http//www.scientificpsychic.com/fitness/carbohydr
ates1.html
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The rest of the plant is mostly sugar too!
Section of a pine board
3 nm
Somerville, 2006
Polymerized glucose
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Plant cell wall
Cell walls fuel
Cellulose,Hemicellulose, lignin
recalcitrance
Cellulose microfibril
chemical pretreatments
Parallel strands of glucose polymers
Cosgrove, 2006
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Components of plant cell walls
Cellulose
Cellulose (6 carbon sugars)
Lignin
Lignin (phenols)
Extractives
Extractives
Hemicellulose (both 5 and 6 carbon sugars) (need
modified microbe to convert to ethanol)
Ash
Ash
Chapple, 2006 Ladisch, 1979, 2006
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Ethanol from glucose or xylose
Jeffries Shi Adv. Bioch Eng 65,118
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Conversion of sugar to alkanes
Huber et al., (2005) Science 308,1446
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Bioconversion Platform
Biomass Feedstock
Feedstock Handling
Pretreatment
Biological Conversion
Product Recovery
Power/TCF Production
Waste Treatment
Lee Lynd, 2006
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_____________
Lee Lynd, 2006
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Biorefinery By-Product Utilization

• Lignin
• Burn to power the plant export electricity
• Platform for specialty chemicals?
• Wastewater
• Conventional treatment? Energy recovery?
• Still Bottoms
• Value as animal feed?
• Fire boiler to supplement heating demand
• Must be dried, co-fired with coal or equivalent
• 5000-8000 BTU/lb

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Ethanol dry-mill with process heat produced by
firing stover in a solid-fuel boiler. Net Energy
12.2 MJ/L
Rob Anex, Iowa State Univ.
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Relative cost factors of cellulosic ethanol
Capital Recovery Charge
Raw Materials
Process Electricity
Grid Electricity
Total Plant Electricity
Fixed Costs
33
Biomass Feedstock
5
Feed Handling
18
Pretreatment / Conditioning
Saccharification and fermentation
12
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
NREL Analysis
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Economic Drivers Biological Processing of
Lignocellulose
0.30
0.25
0.20
0.152
Fermentable Carbohydrate Cost (/kg)
0.148
0.15
0.10
0.05
0.00
With Coproducts
Laser and Lynd, 2007
Corn (dry mill)
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Economic Impact of Various RD-Driven
Improvements
Increase hydrolysis yield
3
Improved feedstock sugars
13
Halve cellulase loading
Eliminate pretreatment
22
Consolidated bioprocessing (CBP)
41
Error bars denote two different base cases
Processing Cost Reduction
18
www.bioenergy.psu.edu Acknowledgements Lee Lynd
and Mark Laser, Dartmouth Rob Anex, Iowa State
University Alex Farrell, UC Berkeley USDA-ARS DOE-
NREL