A Hybrid Pyrolytic-Electrochemical Approach for Creating Fuels from Forest Biomass
Christopher M. Saffron Associate Professor
Department of Biosystems and Agricultural Engineering
Michigan Forest Bioeconomy Conference
February 2nd, 2017 Grand Rapids, MI
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Overview of Thermochemical Conversion Technologies
Increasing Temperature
200°C 400°C 600°C 800°C 1000°C
Torrefaction Fast pyrolysis
Slow pyrolysis*
Gasification (partial oxidation)
Greater than 1,000°C = combustion
Product gases is rich in CO, H2, and light hydrocarbons
Many gasifier configurations have been explored
†http://www.ecn.nl *http://www.biochar-international.org/
†
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Biomass Conversion to Hydrocarbon Fuels Rationale for displacing petroleum • Minimize climate change impact • Promote energy independence and security • Slow resource depletion
~285 billion gal/yr in the U.S. alone
Rationale for pyrolysis/upgrading • First generation biodiesel and ethanol
can provide short-term remedies but have significant challenges
• Industry desires “drop-in” hydrocarbon replacements for petroleum fuels
• Unbeatable energy to weight ratio
• Nature’s choice for energy storage
http://www.heavyequipment.com/heavy-equipment/lumber-forestry
4 Perlack RD and Stokes BJ The U.S. Department of Energy (2011) U.S. Billion-ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry.
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Comparison of Scale: Fossil Energy vs. Bioenergy • Oil: 2012 U.S. consumption about 6.8 billion bbl/yr or 1 billion tons/yr
– C content in “CH2” is 12/14 or 86% → 860 MM tons C/yr – E content: HHV = 45 MJ/kg → 41 EJ/year
• Biomass: 2030 U.S. biomass 1.3 x 109 tons/yr (crop residues, forest wastes, and energy crops)
– C content in “CHOH” is 12/30 or 40% → 520 MM tons C/yr – E content: HHV = 15 MJ/kg → 18 EJ/year (assuming perfect conversions)
• Today’s biofuels: Consider ethanol production: – C6H12O6 → 2CH3CH2OH (MW = 46) + 2CO2 (MW = 44) – Concentrates plant-captured E into half the mass, but throws away 1/3 of
the C – E content: Ethanol doesn’t come close to a 1:1 gasoline or diesel
replacement
• Carbon Efficient Bioenergy Systems Needed! • Energy Upgrading Strategies for Bioenergy Systems Needed!
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Bioenergy System Diagram using Decentralized Depots
Cultivation Harvest Haul Collection
On-site Storage Grind & Dry Fast Pyrolysis &
Condensation
Transport On-site Storage
CentralizedConversion Transport Retail End
Use
CO2 H2O Fertilizers
Solar Energy
CO2, H2O, Shaft Work, Heat Loss
Biomass Upgrading Depot
Utilities, Reagents, Catalysts
Electro-catalysis
Non-carbon Emitting Electricity
Renewable Hydrogen
• Biomass Upgrading Depots (BUDs) are small-scale facilities used to preprocess biomass to improve its physicochemical properties
Biochar backhaul
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Biomass Fast Pyrolysis
Biomass Bio-oil + Char + Gases (100%) = (up to 70%) + (~15%) + (~15%)
• Pyrolysis is thermal decomposition without oxygen – Low energy requirement: Nearly neutral endo- vs. exothermicity – Modest temperatures: Pyrolysis reaction temps. of ca. 500°C – Rapid throughput: Short vapor residence time in the reactor (<1s) – Carbon-retentive: Cellulose, hemicellulose and lignin are liquefied – Densification: Bio-oil specific gravity is 1.1-1.2
→
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Pyrolysis Reactor
Condenser and collection vessels
Biomass feeder and reactor
Electrostatic precipitator
Gas flame calorimeter
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Biomass Fast Pyrolysis
Biomass → Bio-oil + Char + Gases (100%) = (up to 70%) + (~15%) + (~15%)
• Pyrolysis is thermal decomposition without oxygen – Low energy requirement: Nearly neutral endo- vs. exothermicity – Modest temperatures: Pyrolysis reaction temps. of ca. 500°C – Rapid throughput: Short vapor residence time in the reactor (<1s) – Carbon-retentive: Cellulose, hemicellulose and lignin are liquefied – Densification: Bio-oil specific gravity is 1.1-1.2
• Bio-oil unwanted properties (stabilization): – Reactive and unstable: aldehydes, ketones, phenols – Corrosive: carboxylic acids, phenols – Low specific energy: HHV is 15 to 19 MJ/kg
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Bio-oil Reactivity and Instability
Adapted from: Diebold J.P., et al. Review. 1999.
H HO
Bakelite resin
Electrocatalytic Hydrogenation and Deoxygenation
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We,in
Divided batch “H-cell”
Ruthenium on activated carbon cloth catalytic cathode
Nafion membrane
Platinum anode
Upgrading to Improve Energy Content
12 12 Increase in Energy Content
28 30 32 34 36 38 40 42 44 46 48
Guaiacol Phenol Cyclohexanol Cyclohexene Cyclohexane
Hig
her H
eatin
g Va
lue
(MJ/
Kg)
Gasoline Level Bio-oil Model
Compound
Model Monomer Studies using Ru/ACC
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OOH
0.2 M HCl 100 mA 6 hrs @ 80 °CRu/ACC
OHO
+
OHGuaiacol
O
OHO
0.2 M HCl 100 mA 6 hrs @ 80 °CRu/ACC
OHO
+
OH
+
OHO
O
OOOH
Syringaldehyde
0.2 M HCl 100 mA 6 hrs @ 80 °CRu/ACC
OHOO
+
OHO
+
OH
OHEugenol
OH OH0.2 M HCl 100 mA 6 hrs @ 80 °C
Ru/ACC +O
OH
+O O
Vanillin
Raw Bio-Oil
200 mA ECH for
6 hrs
350 mA ECH for
6 hrs
Electrocatalytic Hydrogenation of Raw Bio-oil
• pH increase of 1 was found for both the anode solution and bio-oil at 200 mA
• Volume of anode solution changed from 30mL to 25mL
• Volume of the bio-oil remained essentially the same (30mL to 29.5mL)
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Concentric tube design
Lam, Chun Ho. “Electrocatalytic Upgrading of Biomass Pyrolysis Oils to Chemical and Fuel.” PhD dissertation, Michigan State University. 2014.
Solid polymer electrolyte reactor
An, W.D., J.K. Hong, P.N. Pintauro, K. Warner, and W. Neff, The electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. I. Reactor design and operation. Journal of the American Oil Chemists Society, 1998. 75(8): p. 917-925.
Electrocatalysis Cell Configurations
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Upgrade using Renewable Energy
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Upgrade using Renewable Energy
Pyrolysis conditions: T = 400-600 ºC P = 1 atm
Electrocatalysis conditions: T = 50-99 ºC P = 1 atm V = variable; currently 1-10 Volts in H-cells 5-10x less in flow cells H2 production must be controlled
Hydroprocessing conditions: More severe--up to 2,000
psig H2 Can be managed in large, centralized refineries
100 tons/day 100 MMGal/yr
Minimum Bio-Oil Selling Price (MBOSP)
Minimum Fuel Selling Price (MFSP)
Electrocatalysis:
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In Summary
1. Fast pyrolysis increases the bulk density of biomass
2. Electrocatalysis creates a stable intermediate with high energy density
3. Local wind and solar energy used upgrade biomass’ energy content
4. Pyrolysis and electrocatalysis are simple and performed at safe P
5. Biochar has economic and environmental benefits
6. Pyrolysis and electrocatalysis provides a carbon efficient pathway that increases the amount of energy available as finished fuel
7. Improves growers’ participation in the financial upside, depots will require trained professionals and a professional wage, and the revenue gained will increase the tax base
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Acknowledgements
• Key faculty members: Dr. Ned Jackson, Dr. Dennis Miller
• Other group members: Dr. Shantanu Kelkar, Dr. Zhenglong Li, Dr. Chun Ho Lam, Dr. Li Chai, Dr. Peyman Fasahati, Dr. Ryan Stoklosa, Dr. Mikhail Redko, Dr. Edmund Okoroigwe, Mr. Jon Bovee, Dr. Lars Peereboom, Mr. Souful Bhatia, Dr. Somnath Bhattacharjee, Mrs. Nichole Erickson, Dr. Leonardo Sousa, Mr. Cale Hyzer, Mr. Tom Stuecken, Mrs. Mahlet Garedew, Mrs. Rachael Sak, Mr. Zhongyu Zhang, Mr. Sabyasachi Das, Mrs. Tammy Lin, Mr. Zach Carter, Mr. Pengchao Hao
MTRAC
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Thank you! Questions?
Finelygroundbiomass
Screw-conveyorPyrolysisreactor
Gas
Char
Bio-oil Electrocataly=cHydrogena=on
(ECH)
GasolineDieselJetfuel
Centralrefinery
ECH
Deoxygena=on
Stabilization
Regional biomass processing depots