College of Engineering
Discovery with Purpose www.engineering.iastate.edu
College of Engineering
Engineering a Non-Petroleum Binder for Use
in Flexible Pavements
R. Christopher Williams
Mohamed Abdel Raouf
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Presentation Outline
• Production of bio-oils and characteristics
• Experimental plan and upgrading of bio-oil
• Characteristics of bio asphalt
• Environmental Opportunities
• Summary/Conclusions
• Ongoing and next steps in research
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Impetus for Research
• Developing bio-economy
• Link between bio-economy and transportation
infrastructure
• Renewable sources of materials
• Economic opportunity
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Fast Pyrolysis
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Fast pyrolysis - rapid thermal decomposition of organic compounds in the absence of oxygen to produce gas, char, and liquids• Liquid yields as high as 78% are possible for relatively short residence
times (0.5 - 2 s), moderate temperatures (400-600 oC), and rapid quenching at the end of the process
Biomass
Monomers/
Isomers
Low Mol.Wt Species
Ring-opened Chains
H+
H+
M+M+
Aerosols
High MW
Species
Gases/Vapors
Thermo-
mechanical
Ejection
Vaporization
Molten
Biomass
T ~ 430oC(dT/dt)→∞
CO + H2
Synthesis Gas
Reforming
TM+
Volatile Products
M+ : Catalyzed by Alkaline Cations
H+ : Catalyzed by Acids
TM+ : Catalyzed by Zero Valent Transition Metals
(Observed at very
high heating rates)
Oligomers Source: Raedlin (1999)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Corn stover (0.5-1.0mm)10 run average, different conditions
sbio-oil = 6.09%; schar= 8.27%
Corn fiber (1.0 mm)2 run average, same conditions
sbio-oil = 1.33%; schar= 0.148%
26%
18%
56%
Red oak (0.75 mm)6 run average, different conditions
sbio-oil = 2.21%; schar= 1.89%
17%
12%
69%
2%
37%30%
33%
Bio-oil Biochar Gas Unaccounted
*Auger pyrolyzer, ISU (2008)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Efficiency and cost of bio-oil production
• Energy efficiency
• Conversion to 75 wt-% bio-oil translates to
energy efficiency of 70%
• If carbon used for energy source (process
heat or slurried with liquid) then efficiency
approaches 94%
• Cost
• $17-$30/bbl (assuming feedstock cost of
$50/ton)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Bio-Oil • Advantages include:
• Liquid fuel
• Decoupled conversion processes
• Easier to transport than biomass or syngas
• Disadvantages• High oxygen and water content
makes bio-oil inferior to petroleum-derived fuels
• Phase-separation and polymerization and corrosiveness make long-term storage difficult
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Recovery of Bio-oil as Fractions
Fraction
1
Fraction
2
Fraction
3
Fraction
4
Yield (wt-% of biomass) 8.0% 6.0% 29.2% 21.3%
Moisture 1.54% 6.43% 5.63% 74.94%
Major chemicals levoglucosan phenolics lignin oligomers acids
Pyrolyzed corn fiber from wet milling
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Characteristics of Bio-oil Fractions
Property Cond. 1 Cond. 2 Cond. 3 Cond. 4 ESP
Fraction of total oil (wt%)6 22 37 15 20
pH- 3.5 2.7 2.5 3.3
Viscosity @40oC (cSt)Solid 149 2.2 2.6 543
Lignin Content (wt%)High 32 5.0 2.6 50
Water Content (wt%)Low 9.3 46 46 3.3
C/H/O Molar Ratio1/1.2/0.5 1/1.6/0.6 1/2.5/2 1/2.5/1.5 1/1.5/0.5
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Products Generated from Bio-Oil
• Biomass pyrolyzed to bio-oil
• Bio-oil fractions converted to renewable fuel, asphalt, and other products
Pyrolyzer
Sugars Phenols Acids
Fuel Asphalt Co-Products
Biomass
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Experimental PlanBlend # Binder Type Polymer Modifier Type Blending Percentage
AAMBitumen None None
AAD
Blend 1
Oakwood Bio-oil
Control
Blend 2 P1 2
Blend 3 P1 4
Blend 4 P2 2
Blend 5 P2 4
Blend 6 P3 2
Blend 7 P3 4
PropertyPolyethylene
(P1)
Oxidized
Polyethylene
(P2)
Polyethylene
(P3)
Drop Point, Mettler (°C) 101 108 115
Density (g/cc) 0.91 0.93 0.93
Viscosity @140°C (cps) 180 250 450
Bulk Density (kg/m3) 563 536 508
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Viscosity-Temperature Susceptibility
0
0.1
0.2
0.3
0.4
0.5
0.6
2.74 2.76 2.78 2.80 2.82 2.84 2.86 2.88 2.90
Log L
og V
isco
sity
(P
a·s
)
Log Temperature (Rankine)
Blend 1 Blend 2 Blend 3 Blend 4 Blend 5
Blend 6 Blend 7 AAM AAD
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Effect of Shear Rate on Viscosity
0
1000
2000
3000
4000
5000
6000
7000
0 20 40 60 80 100 120
Vis
cosi
ty (
cP)
Shear Rate (rpm)
AAM at 110 AAD at 110 Blend 1 at 60
Blend 2 at 60 Blend 3 at 60 Blend 4 at 100
Blend 5 at 100 Blend 6 at 100 Blend 7 at 100
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Arrhenius Model for AAM
R² = 0.9936
0
2
4
6
8
10
12
2.7E-04 2.8E-04 2.9E-04 3.0E-04 3.1E-04 3.2E-04 3.3E-04 3.4E-04
Log V
isco
sity
(P
a.S
)
1/R*Temp (K)
2
4
10
20
50
100
Expon. (20)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Arrhenius Model for AAD
R² = 0.9934
0
2
4
6
8
10
12
2.7E-04 2.8E-04 2.9E-04 3.0E-04 3.1E-04 3.2E-04 3.3E-04 3.4E-04
Log V
isco
sity
(P
a.S
)
1/R*Temp (K)
2
4
10
20
50
100
Expon. (20)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Arrhenius Model for Blend 1
R² = 0.9889
0
2
4
6
8
10
12
3.3E-04 3.4E-04 3.5E-04 3.6E-04 3.7E-04 3.8E-04 3.9E-04
Log V
isco
sity
(P
a.S
)
1/R*Temp (K)
2
4
10
20
50
100
Expon. (20)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Arrhenius Model for Blend 2
R² = 0.9991
0
5
10
15
20
25
30
35
40
3.3E-04 3.4E-04 3.5E-04 3.6E-04 3.7E-04 3.8E-04 3.9E-04
Log V
isco
sity
(P
a.S
)
1/R*Temp (K)
2
4
10
20
50
100
Expon. (20)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Arrhenius Model for Blend 4
R² = 0.9774
0
2
4
6
8
10
12
2.7E-04 2.8E-04 2.9E-04 3.0E-04 3.1E-04 3.2E-04 3.3E-04 3.4E-04
Log V
isco
sity
(P
a.S
)
1/R*Temp (K)
2
4
10
20
50
100
Expon. (20)
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Secondary Charcoal Generation
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Nature, Vol. 442, 10 Aug 2006
Bio-char: Soil amendment & carbon sequestration
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
*However, biochar quality is very important. The wrong type of biocharcan cause yield decreases!
Several studies have reported large
increases in crop yields from the use
of biochar as a soil amendment.
However, most of these studies were
conducted in the tropics on low
fertility soils. Need to study how
temperate region soils will respond
to biochar amendments. 20000
22000
24000
26000
28000
30000
Pla
nt
Po
pu
lati
on
(p
lan
ts/A
c)
Control Biochar
(4.4 ton/Ac)
Biochar
(8.2 ton/Ac)
B
AB
A
Plant Population on 6/24/08(Seeding rate 30000)
160
170
180
190
Yie
ld (
bu
/Ac
)
Control Biochar
(4.4 ton/ac)
B
Biochar
(8.2 ton/ac)
AB
A
175 bu/ac
n = 12
177 bu/ac
n = 12171 bu/ac
n = 32
Corn yield 2008 (56 total plots)
First year trials in Iowa showed a
15% increase plant populations,
and a 4% increase in corn grain
yield from biochar applications.*
Laird et al.
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Ca
rbo
n S
tore
d (
lb/a
cre
/yr)
Greenhouse gases reduced by
carbon storage in agricultural soils
0200400600800
100012001400160018002000
Pyrolytic Char No-Till Switchgrass
No-Till Corn Plow-Tilled Corn
Char from pyrolyzing one-half of corn stover
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Summary
• Bio asphalt has similar temperature sensitivity to
petroleum derived asphalt.
• The temperature range for the bio-oil and bitumen
blends were different.
• An asphalt derived from biomass has been
developed that behaves like a viscoelastic material
just like petroleum derived asphalt.
• The bio asphalt can be produced locally
• The production process sequesters greenhouse
gases.
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Ongoing Activities
• Performance grade binders have been developed
• Mix performance testing
• Rutting
• Fatigue Cracking
• Thermal Cracking
• Building test pavement sections
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Moving Forward
• Laboratory mix performance
• Scale up of production facilities
• Substantial capital investment
• Multiple end markets for pyrolysis products
• Demonstration projects
• Biomass composition varies, and thus products can
vary
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Thanks & Acknowledgements
• Center for Sustainable Environmental Technology
• Robert Brown
• Sam Jones, Marge Rover
• Iowa Energy Center
• Iowa Department of Transportation
• Mark Dunn & Sandra Larson
• Scott Schram, John Hinrichsen & Jim Berger
• Iowa Highway Research Board
• Counties and Local Agencies
• Asphalt Paving Association of Iowa
College of Engineering
Discovery with Purpose www.engineering.iastate.edu
Thank You!
&
Questions?