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Biomass Basics:
Renewable Energy and Chemicals
Dennis J. Miller
Department of Chemical Engineering and Materials
Science
Michigan State University
East Lansing, Michigan 48824
(517) 353-3928
[email protected]
Benefits of the Chemical Industry
Tell Our Students About It!!
The Emerging Paradigm:
Sustainability and Green Chemistry
"Sustainable development
is development that meets
the needs of the present
without compromising the
ability of future generations
to meet their own needs.”
The Brundtland
Commission Report, The
United Nations, 1987.
• Environmentally Sustainable
• Economically Sustainable
• Socially Sustainable
Petroleum
www.bp.com
Distribution of proven (oil) reserves
1984,1994, 2004
Oil reserves-to-production (R/P) ratios
Oil consumption by region
Major oil trade movements
Energy Consumption Concepts
(A great web site: www.bp.com)
• Material and Energy Balances
– How much fossil energy in MJ (oil, coal, gas)
does the world use annually?
– How much oil does the U.S. use annually?
(A: about 1.5 cubic miles)
– How many watts per person does that equate
to in the U.S.?
Biorenewable Fuels and Chemicals
Corn: The Near-term Biofuels Feedstock
2005 Statistics
• Production:
• Acres planted:
• Average yield:
11.8 billion Bushels
80.9 million acres
160 bushels/acre
(vs. 137 bu/a in 2000!)
The corn plant
• 3.8 tons corn stover / acre (lignocellulosic)
• 3.8 tons corn grain / acre
Societal/Global perspective questions:
How much of our fuel needs can corn provide?
What are the costs associated with using corn for fuel?
How does politics enter into corn ethanol?
Corn to ethanol energetics
C6H12O6
glucose
1.0 kg
17 MJ
=
2 C2H5OH +
ethanol
0.51 kg
15.8 MJ
Theoretical yield
EtOH yield (grain only):
EtOH yield w/ 50% stover:
• Ethanol energy content
• Gasoline energy content
2 CO2
carbon dioxide
0.49 kg
0 MJ
2.7 gal/bu
450 gal/acre
670 gal/acre
80,000 Btu/gal
130,000 Btu/gal
Ethanol fuel supply
•
U.S. gasoline consumption (2006):
150 billion gal
•
U.S. fuel ethanol consumption (2006):
6 billion gal
– 4% of total gasoline demand
– Blended 10% with gasoline (40% of U.S. gasoline contains ethanol)
– 14 million of 80 million acres of corn harvested
Ethanol energy exercises
•
How much corn would be required to provide E10 for the entire U.S.?
A: About ~5 billion bushels (40% of 2006 U.S. crop)
•
What land mass would be required to replace all U.S. gasoline with
ethanol?
A: 200 billion gal EtOH equates to 75 billion bushels corn / yr or
300+ million acres (22% of U.S. landmass)!
Cellulosic Biomass – long-term
renewable biofuel feedstock
Composition (wt%)
Cellulose
Hemicellulose
Lignin
Yield (ton/acre)
Ethanol yield (gal/ton)
Wood
55
20
25
3-8
90 - 100
Switchgrass
55
30
15
3 - 10
90 - 100
Challenges
– Switchgrass is low-density compared to corn, more
costly to collect and transport.
– Cellulose difficult to hydrolyze (structural polymer);
starch is amorphous and easy to hydrolyze.
– Can burn lignin to provide energy for plant operation
Senior Design Problem:
Bioenergy plantation design
• Fundamental concept: there exists an optimum
biorefinery capacity (M) for biofuel production.
(Tradeoff between capital cost (~M0.6) and cost
of transporting biomass (~M1.5)).
• Process energy provided by lignin combustion
• Can choose parameters arbitrarily or use
standard values (NREL website).
• Possibilities for open-ended design, multiple
smaller “feeder” process units in remote
locations.
Biomass Plantation Economics (NREL)
Biodiesel from plant oils
R
O
+
O
R''
O
OH
OH- or H+
O
3
OH
HO
O
+
3
O
O
R
OH
O
R'
Plant oil
(triglyceride)
methanol
glycerol
acid methyl ester
(biodiesel)
• Plant oils include soy, rapeseed, canola, etc..
• Waste cooking oils are minor potential source, are inexpensive,
but contain water and free fatty acids that must be cleaned up.
•Other sources include algae, sewage, etc..
• Reversible reaction system
•Typical methanol:oil feed ratio of 6:1 gives two product phases,
>98% methyl ester yield
Current biodiesel production
(Batch production, labor and energy intensive)
purification Biodiesel
Product
(100 kg)
(30 gal)
Plant oil (100 kg)
(30 gal)
Methanol (22 kg)
(6:1 ratio)
NaOCH3 (0.5 kg)
60oC, 2 hr
Neutralize
purify
Glycerol
byproduct
Glycerol
(10.4 kg)
+
(0.7 lb/gallon)
NaOCH3
Biodiesel in the classroom
Material and energy balances:
a) Calculate stoichiometric reaction masses, byproduct glycerine yields
b) Calculate biodiesel energy density relative to diesel fuel
c) Optimizing energy yields from land - Which fuel type gives higher
energy yield per acre, biodiesel or ethanol?
Canola: 1000 kg/acre*0.44 kg oil/kg canola*39 mJ/kg = 17160 MJ/acre
Ethanol: 160 bu/acre*2.7 gal/bu*3 kg/bu*27 MJ/kg = 35000 MJ/acre
Reaction engineering:
Make biodiesel as classroom demo (cooking oil + methanol + sodium
hydroxide/methoxide)
Good example of homogeneous catalysis (can see color change upon
addition of sodium hydroxide in methanol)
Chemical Building Blocks from Biomass
Carbon number
C1
C2
C3
C4
C5
C6
C 7, C 8
Biomass Blocks
Petroleum Blocks
methanol, CO
methane
acetic acid, ethanol
ethylene
lactic acid, acetone,
propylene
propionic acid, glycerol
succinic acid, n-butanol
isobutylene
3-hydroxybutyrate
butadiene
xylose, glutamic acid
3-hydroxyvalerate
glucose, lysine
benzene
toluene
xylene
Chemicals from Carbohydrates
BIOMASS
(CORN, WOOD..)
STARCH
CORN
CELLULOSE
Industrial starches,
cellulose derivatives
GLUCOSE
Syrups, sweeteners
Fermentation
Organic acids
Ethanol
Lactic acid
Succinic acid
Citric acid
Acetic acid
Propionic acid
Itaconic acid
Lysine
D,L-Methionine
Other amino acids
Aromatics
Others
Chemical conversion
O2
H2
Polymers
Gluconic acid
Sorbitol
1,3-propanediol Starch copolymers
2,3-butanediol
Xanthan gum
ABE
Alginates
Hydroxyalkanoate
PG, EG
Glycerol
Sorbitan
Ascorbic
acid
OH
Lactic Acid
Fermentation: C6H12O6
(glucose)

CH3 CH C
O
OH
2 C3H6O3
(lactic acid)
- Yields exceed 0.95 lb/lb glucose
- Product concentrations > 90 g/L
- Production rates > 3 g / L· hr
- Ca(OH)2 to neutralize, acidulation w/ H2SO4 (CaSO4 waste)
Production cost:
< $0.25 / lb
Production capacity: 350 MM lb/yr (Cargill)
100 MM lb/yr (all others)
Equilibrium Lactate Ester Reactions
OH
L1
O
W
O
Et
W
L1
OH
L2
O
L 2E
W
L2
W
OH
O
L1E
Et
Et
Et
Et
Et
L1
O
Et
OC2H5
L3
L 3E
Et
L 4E
W
O
Et
L2E
L1
W
L4
W
- Lactic acid oligomerization reactions characterized by Ke = 0.23
Nominal lactic acid
concentration (wt%)
Equilibrium oligomer distribution
L1
L2
L3
L4
20
20
-
-
-
50
42
8
-
-
88
58
22
6
2
Lactate esters via reactive distillation
Lactic Acid +
Ethanol
=
Ethyl lactate + Water
Ethanol + Water
Lactic Acid
Ethanol
Water
Ethyl Lactate
Ethyl Lactate (+ oligomers)
Reactive distillation for lactate ester production
Feed Stream 1
Stream 3
Flow 21.87 kmol/hr 25C
Flow 65.98 kmol/hr
Wt %
FEED (88% LA feed)
LA
: 9.519
L2 Acid : 2.005
L3 Acid : 0.505
Water : 9.847
EtOH : 54.000
kmol/hr
kmol/hr
kmol/hr
kmol/hr
kmol/hr
LA
Water
L2 Acid
L3 Acid
Wt %
58.0
14.0
22.0
8.0
EtOH
EtLA
Water
7
82.93
0.13
16.94
10
Feed Stream 2
Flow 54.0 kmol/hr 85C 1.16 atm
EtOH
Wt %
Stream 4
100.0
Flow 9.90 kmol/hr
30
Wt %
# Stages
Reflux ratio
35
0.1
Lactic acid conversion (%) >99
35
LA
EtOH
EtLA
Water
L2ES
L3ES
L2 Acid
L3Acid
0.00
0.30
72.64
0.13
19.44
6.11
0.66
0.63
Chemicals from Renewables
• Material balances/reaction engineering: Determine
theoretical yields - renewables generally undergo weight
loss in conversion, whereas petroleum generally
undergoes weight gain in conversion.
• Separations: schemes for purifying low volatility
organic/renewable products (evaporation, reactive
distillation, chromatography, other novel separations)
• Thermodynamics: Many biobased reactions are
reversible, involve nonideal solutions, physical properties
estimation required
Summary
• Renewable fuels and chemicals can be
incorporated across the core ChE curriculum
– Energy and mass balance calculations
– Thermodynamics: physical properties, phase
equilibria, reaction equilibria
– Reaction engineering: kinetics, reactor design,
catalysis
– Separations: design separations schemes for nonvolatile, thermally fragile compounds
– Process design: core chemical engineering principles
and unit operations are key to designing biorefineries
GREEN CHEMISTRY
DEFINITION
Green Chemistry is the utilisation of a set of principles that reduces
or eliminates the use or generation of hazardous substances in
the design, manufacture and application of chemical products *.
GREEN CHEMISTRY IS ABOUT (12 principles)
•
•
•
•
•
•
Waste Minimisation at Source
Use of Catalysts in place of Reagents
Using Non-Toxic Reagents
Use of Renewable Resources
Improved Atom Efficiency
Use of Solvent Free or Recyclable Environmentally Benign Solvent
systems
Traditional Synthesis of Ibuprofen
O
O
CHCO2C2H5
ClCH2CO2C 2H5
(CH3CO)2O
NaOC2H5
AlCl3
I¯Bu
I¯Bu
CH
CHO
NOH
H2NOH
H+
H20
C
I¯Bu
I¯Bu
N
CO2H
Ibuprofen
I¯Bu
(BASF and Celanese Corporation)
60% Waste
Green Chemistry Alternative
Synthesis of Ibuprofen
PGCC Winner 1997
O
(CH3CO)2O
HF
H2
+ CH3COOH
OH
catalyst
CO2H
CO, Pd
1% Waste
Ibuprofen
(BASF and Celanese Corporation)
Green chemistry in the curriculum
• Material and Energy Balances
– Define and implement atom economy and waste
generation into stoichiometry problems
– Yield calculations for multiple step syntheses
• Reaction Engineering and Design courses
– Carry out reactor design for green process and
compare with traditional process
• Resource: ACS Green Chemistry Institute