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Diluted acid pretreatment for an integrated microalgae bio-refinery to produce lipid- and
carbohydrate-based biofuels
Tao Dong, Lieve Laurens, Nick Nagle, Stefanie Van Wychen,
Nicholas Sweeney, Philip Pienkos
Algae Biomass Summit
San Diego, California
Sep. 30, 2014
Introduction
• Integrated bio-refinery process for multiple products recovery from algal biomass
• Response of carbohydrate and lipids recovery under diluted acid pretreatment
• Biomass morphological changes in cellular structure after pretreatment
• Conclusion
Biomass fractionation for fuels & value-added chemicals
Proteins
Ethanol
Succinic acid
FarneseneFermentation
Blend stocks
Aviation Fuel
Green DieselHDO/HI
Lipids
ADfermentation, etc
Animal feed
Isobutanol
Bio-plastics
Methane
Proteins
Scheme for integrated algal biomass processing
Fuel HL NC HL SD
Fatty acids (FAME)(% DW)
57.3 38.6
Diesel equivalent (gallon/ton)
138.4 93.2
Fermentable Sugars(% DW)
10.9 39.4
Ethanol(gallon/ton)
13.8 59.0
Total fuel energy (103 Btu/ton)
18060 15965
Total GGEper ton biomass (GGE/ton)
155.6 137.5
A-100Feedstock
A-200Pretreatment
A-300S/L
Separation
A-500Fermentation
A-600EtOH
Recovery
A-325Extraction
A-375Protein Extract.
A-400Butanol Ferm
A-350Lipid
Recovery
A-360AnaerobicDigestion
A-450Butanol
Recovery
Algae Water Acid Steam
Slurry Liquor
Media KOH
Solids Liquor
Hexane
Liquor
Solids
Solids
Solids NaOH
Algal feedstock production at ASU
Using a Combination of PBR’s and Open Raceways
Three Production Strains:• Chlorella sp.• Scenedesmus sp. • Nannochloropsis sp.
Three Growth Regimes:•High Protein (Early)•High Carbohydrate(Mid)•High Lipid (Late)
Feedstock Composition and Rates of Lipid Accumulation
Chlorella sp. Scenedesmus sp.Nannochloropsis sp.
Early (high protein)Mid (high carbohydrate)Late (high lipid)
Dilute-acid pretreatment to release lipid & carbohydrate
• CEM Explorer Microwave Reactor• Automated system w/36-positions• 300 watt output• Stir bar mixing• Rapid heating
Aci
d
Temperature
145 ºC, 2% H2SO4
• Track both fatty acid and carbohydrate release
• Central Composite Design
1751170%
4.1%
FFA
TAG
FFA
TAG
FFA
TAG
HC CZ HL CZ
HC SD HL SD
HL NC
Response of lipids recovery from different strains
SD
CZ
NC
Mid HC Late HL
Element HL CZ HC CZ HL SD HC SD HL NC
Carbon 76.83 77.42 77.53 76.61 76.87
Hydrogen 11.74 11.54 12.00 11.91 11.77
Nitrogen 0.04 0.05 0.03 0.10 0.09
Oxygen 11.86 11.37 11.04 11.93 11.96
Sulfur 0.004 0.006 0.005 0.026 0.036
Phosphorus <0.001 <0.001 <0.001 0.001 0.039
80%
90%
100%
80%
90%
100%
MicroalgaeGlucose
Galactose/Rhamnose
Mannose
% (based on total carb)HCNC 69.6 21.4 8.9HLNC 72.5 18.3 9.2
HCCZ 80.1 17.0 2.9HLCZ 84.9 12.1 3.0
HCSD 81.7 3.8 14.5HLSD 75.9 3.3 20.8
NC: LaminarinCZ: StarchSD: Glucomannan
Response of carbohydrate recovery from different strains
SD
CZ
NC
Mid HC Late HL
Energy yield from integrated algal biomass processing
SD CZ NC
mid late late late
Gasoline equivalent
(gal/ton)** 34 27 23 8
Btu equivalent
(x10e3) 3959 3156 2700 948
Diesel equivalent
(gal/ton) 37 84 50 111
Btu equivalent
(x10e3) 4541 10311 6171 13605
Total fuel energy
(x10e3 Btu/ton) 8500 13467 8871 14553
Total GGE
(GGE/ ton) 73 116 76 125
SD
CZ
NC
Mid HC Late HL
Biomass morphological changes in cellular structure
HL NC
HL CZ
HC SD
Conclusion
• Integrated microalgae biomass processing is able to recovery lipids and fermentable sugar.
• Acid concentration and temperature have combined effects for lipids and sugar recovery.
• The response of microalgae biomass to pretreatment is strain-dependent
• Achieve >100 GGE/ton for the late harvest Scenedesmussp. and Nannochloropsis sp. strains.
Acknowledgements
NREL
Deborah Hyman
Kelsey Ramirez
Robert Sebag
Paris Spinelli
Chandler Ridler
Earl Christensen
ASU:
John McGowen (ASU)
Thomas Dempster (ASU)
BETO
THANKS! QUESTIONS?
% DW FAME Lipids ash Carbohydrates Glucose Xylose Galactose Arabinose Mannose ProteinHP NC 12.3 14.2 8.9 5.1 0.0 2.9 0.0 0.9 32.7HC NC 25.6 13.6 11.1 7.8 0.0 2.4 0.0 1.0 23.1HL NC 57.3 5.1 10.9 7.9 0.0 2.0 0.0 1.0 9.4
HP SD 9.1 4.5 16.9 7.5 0.0 2.8 0.0 6.6 46.3HC SD 17.0 1.8 49.7 40.6 0.0 1.9 0.0 7.2 17.4HL SD 38.6 2.2 39.4 29.9 0.0 1.3 0.0 8.2 7.8
HP CZ 12.1 6.7 11.1 3.6 0.5 5.6 0.5 1.0 43.2HC CZ 15.0 4.4 35.7 27.8 0.5 5.9 0.5 1.0 24.0HL CZ 23.1 5.3 38.0 31.5 0.5 4.5 0.4 1.1 15.2
Integrated processing of microalgae biomass
Hydrodeoxygenation (HDO) of Algae Oil
• Left: high-lipid Chlorellaoil at 25 wt% in hexane
• Right: Chlorella oil HDO product over Pd/C– 450 °C, 1300 psi H2
– Residence time ~2 min; LHSV = 1 hr-1
– GC-MS: primarily C15 and C17 n-alkanes
Before After
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