Co-producing Biofuels and Animal Feeds at Regional
Biomass Processing Depots
Bryan BalsMichigan State University
Presented at Frontiers in Biorefining10/20/2010
Not asking the right questionsWe cannot force bioenergy into the current agricultural landscape and expect it to work
Agriculture has changed before; it can change again
We must examine the actual uses of land rather than relying on intuitive “gut reactions”
Most agricultural land is used for animal feed, NOT direct human consumptionCropland is currently not used efficiently; we actually have more than enough land
Solution: new technologies for better animal feed and improved productivity of land
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Questions for a Biofuels Future
Premise: the cellulosic biofuels industry will grow rapidly in the coming decades.While we build the first plants & set up the first supply chains, let us remember what the ultimate system will look like and keep the following questions in mind:
How can uniform, reproducible supply chains develop?How can we commoditize biomass?How can we improve the environmental performance of our systems?Given a large biofuel demand, what are the implications for food/feed/fiber markets? Can we coproduce fuels (& foods/feeds)?How can farmers & local communities benefit?
Attacking Biomass Supply Challenges: Regional Biomass Processing Depots (RPBDs)
Partners:Iowa State U.
Idaho National Lab.Pennsylvania State U.
Michigan State U.
Objective: convert regional, distinct biomass sources into dense, stable,
shippable intermediate commodities for later upgrading at (bio)refinerie
Advantages of RBPDsAddress biomass variability near point of productionProduce dense, stable, shippable intermediate commodities for biofuel producers (“biorefineries”)Reduce transaction costs & capital risks for biorefineriesBenefit rural communities through job creation & ownership Address “food vs. fuel” and sustainability issues directly
Research needs to implement RBPDsOptimize in field harvest/storage/logistical systemsOptimize supply chain for “best” intermediate productsConduct technoeconomic and life cycle studies Develop processing technology/property data for biofuelintermediates & coproducts (eg, biochar, animal feeds)
Advantages and R&D Needs for Regional Biomass Processing Depots
Sustainable rural economies + Sustainable
biofuels
RBPC System Effect 1 – Larger
Biorefineries in high yield areas
Effect 2 – biorefiners in remote rural areas
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AFEX-Treated Fibrous FeedsProblem: Energy in the form of cellulose
Early Forages – low yields, expensiveLate Forages – indigestible, low nitrogen
Partial solution: Gaseous ammoniationOnly modest improvements in digestibility seenIncreases nitrogen content
AFEX – Ammonia Fiber ExpansionA leading pretreatment for biofuels via sugar platformBetter fiber disruption than conventional ammoniation for forages—better animal feed
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Reactor Explosion
AmmoniaRecovery
BiomassTreatedBiomass
RecycleAmmonia
GaseousAmmonia
Reactor Expansion
AmmoniaRecovery
BiomassTreatedBiomass
AmmoniaGaseousAmmonia
Heat
AFEX Process Overview
AFEX process description and properties•hot, concentrated (~15M) ammonia:water mix, short rxn time
•rapid pressure release ends treatment, cools system•little biomass degradation, high yields, residual ammonia value
•no separate liquid phase (“dry to dry”)—very high solids loadings possible
•Typical process conditions•Pressure 20-30 atm
•Temperature 70-140 C•Residence time 5-10 minutes
•Ammonia: dry biomass loading (0.3 -2.0 to 1) (w/w)•Water: dry biomass content (0.2 – 2.5 to 1) (w/w)
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Total Digestible Nutrients, Net Energy for Lactation, and Crude Protein
TDN NEL CP
% DM Mcal/lb % DM
Corn grain 88.7 0.91 9.4
Corn silage 68.8 0.66 8.8
Orchardgrass hay 63.1 0.62 18.1
Alfalfa hay 58.9 0.58 20.2
AFEX Corn Stover 75.6 0.79 17.2
AFEX Switchgrass - late 63.0 0.67 14.6
All values except AFEX materials obtained from Nutrient Requirements of Dairy Cattle, NRC 2001
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Economics
NCSU UWisc Average
AFEX Corn Stover $182 $151 $167
AFEX Switchgrass $153 $132 $143
Alfalfa Hay $176 $160 $168
Corn Grain $145
Soybean Meal 48% $320
Expected corn stover production costs: $40-50/ton
Increase value by over $100/ton
AFEX Biomass Pellets: No Binder
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Bulk density: 6 pounds/cubic foot
Bulk density: 50 pounds/cubic foot
Estimated cost to pellet: $5-10/ton (per Federal Machine, Fargo, ND)
Leaf Protein Concentrates
Crop Average Yield(tons/acre/year)
Protein Content(dry mass %)
Protein Produced(tons/acre/year)
Switchgrass 5.0 – 10 5 - 10% 0.25 – 1.0Soybeans 1.2 – 1.4 40% 0.5 – 0.6Alfalfa 3.7 – 5.0 20 - 25% 0.8 – 1.2Mixed forages 3.3 – 4.6 15 – 25% 0.5 – 1.2Double crop 1.0 - 2.5 10 - 20% 0.1 - 0.5
Leaf protein readily abundant, but trapped with indigestible fibrous material
Solution: separate protein from fiberLeaf protein replaces soy meal & is more land efficient
Fiber can be used for ethanol production Successfully produced at commercial scales
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Economics of leaf protein production
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The Regional Biomass Processing Center (RBPC) Approach
ProteinRecovery
ProteinExtraction
Protein
Grinding Hydrolysis/FermentationPretreatment
Distillation
Ethanol
Ammonia
Whey
Enzymes
Solubles
RBPC
ForageFeed
Fast Pyrolysis
Low temperature rapid burning of biomass without oxygenUp to 75% of biomass by weight becomes oil
Fast Pyrolysis – Bio-oil
Bio-oil: main output of fast pyrolysisAcidic mixture of aldehydes, carboxylic acid, lignins, water, and other componentsLow viscosity liquid
Suitable for standalone diesel engines, can be upgraded to renewable diesel with hydrogen additionMajor setback – corrosive, unstable
Add alkaline material at RBPD, stabilizers before shipping to oil refinery
Biochar – Co-product
Solid, carbon rich residue of fast pyrolisisprocess
Used as fertilizer supplementAlternate #1: Burn/Digest for energyAlternate #2: Activated carbon
Integration into RBPD
Waste heat – 500 – 600CProvide heat integration for AFEX, drying, and other
Biochar – anaerobic digestion?Alternate form of steam or powerIntegrate with farms for soil organic carbon
Diversify feedstocksWoody materials for pyrolysisGrasses for AFEX treatment
Anaerobic digestion
Take in excess manure from surrounding animal farms
Provide methane for heat/electricity for remaining operationsTake in excess biomass when other operations are inoperable/at capacitySell excess methane?
Advanced #1) Enzymes
AFEX-treated biomass is rich in nutrients and adequate for fermentationPossible to produce oligomers that can stimulate cellulase and hemicellulaseproduction
Option 1) In-house enzyme productionOption 2) Commercial enzyme production
Enzyme production
AFEX-CS Lactose0
2
4
6
8
Suga
r Con
cent
ratio
n (g
/L)
Materials Used for Induction (on the same sugar weight basis)
0 1 2 10 (Std Mix)0
2
4
6
8
10
12
14
16
18
Exogenous Enzyme Addition (mg/g CS)
Olig Xyl Olig Glc Cellobiose Mon Xyl Mon Glc
1:6 diluted T. reseei broth
Advanced #2) N-based chemicals
Already extracting protein from biomassProtease digestion of proteinCurrent work – wheat stillage
14.4% solids28% protein (solids only): ~18% initially soluble0.1, 1.0% protease loading (g/g solids) – Protex14L, 6L24h residence time at 50C
Effectiveness of different proteases
0
10
20
30
40
50
60
70
6L 14L 51P 14L/51P
Per
cen
t so
lub
ilize
d (
%)
Protein SolubilizedMass Solubilized
Protease Digestion – Protein balance
0%
3%
6%
9%
12%
15%
18%
ALA ARG ASX GLY HIS ILE LEU LYS PHE PRO THR TYR VAL
Protex 6Luntreated - solubleuntreated
Possible End Product - Cyanophycin
Cyanophycin – produced via fermentationFinal products – acrylonitrile, acrylamide
Konst et al., Green Chemistry 2009, 11:1646
Key Points
Biomass supply issues are key to producing a strident cellulosic biorefinery industryMultiple technologies can combine in a small scale – Regional Biomass Processing DepotsAnimal feeds are a near term co-product to making biofuel production profitable
Also eliminate the “Food vs Fuel” argument
Such RBPDs are amenable to upgrading to future value-added products as well
Biomass Conversion Research Laboratory
www.glbrc.org 28