Let’s envision an
ideal biofuel process
Feedstock
CO2
Biomass

Biomass



Plants



Use solar energy to convert water and CO2 to sugars through the
process of photosynthesis
Harvested portions of live plants or remains are sources of biomass
Animals



Plants
Animals (by way of plants)
Consume plants (or consumers of plants)
Elimination products or remains are sources of biomass
Virtually all of our current energy supply is derived from
biomass (fossil fuels are just “well-aged”)
Multiple Feedstocks
•
•
•
•
trees
grass
agricultural residues
energy crops
• municipal solid waste
• sewage sludge
• animal manure
U.S. Biodegradable Wastes
Amount
Alcohol Potential
Waste
(million tonne/year)
(billion gal/year)
Municipal Solid Waste
78
10
1.4
Sewage Sludge
10.9
Industrial Biosludge
3
0.4
4.3
Recycled Paper Fines
0.5
400
Agricultural Residues
52
330
Forestry Residues
43
220
28
Manure
135
1,046
Total
U.S. Gasoline Consumption = 130 billion gal/year
U.S. Diesel Consumption = 40 billion gal/year
How to Get Liquid Transportation
Fuels from Biomass
Convert sugars and starches to ethanol –
fermentation
 Convert plant oils to biodiesel –
transesterification
 Convert anything to liquid – pyrolysis
 Convert anything to gas (gasification) with
subsequent conversion to liquid – aka biomass
to liquids (BTL)

forest
waste
The Challenge
Lignocellulose
Fisher-Tropsch
Gasification to “syngas” (CO + H2)
methanol
corn
stover
Jet Fuel
gases
Pyrolysis, fast or slow
switchgrass
Diesel
bio-oil
Dissolution
Liquid Phase Processing
Sugar/starch
corn
grain
starch
Gasoline
Saccharification
lignin
burn
sugarcane
Enzymatic Fermentation
sugar
Ethanol
Can we achieve sufficiently high yields of targeted chemical
compounds from solubilized biomass fractions to justify the cost
of biomass pretreatment?
Biofuels, in Order of Maturity, p1 of 2
FUEL
SOURCE
BENEFITS
STATUS
Grain/Sugar
Ethanol
Corn, sorghum,
sugarcane
High-octane
Widely available sources
Commercially
proven
Biodiesel
Vegetable and seed
oils; fats and greases
Increased fuel lubricity
Widely available sources
Commercially
proven
Gasoline and
diesel blends
Ethanol or biodiesel
blended with
petroleum fuels
Relatively straightforward for
Commercial trials
refineries to process
in progress
Decreased sulfur emissions over
standard fuels
Cellulosic
Ethanol
Grasses, wood chips, High-octane
and agricultural
Less demand on agricultural
residues
lands than grain ethanol
DOE program
targeting 2012
demonstration
Butanol
Corn, sorghum,
wheat, sugarcane
BP and DuPont in
progress
Low-volatility
High energy-density
Water tolerant
Adopted from NREL (2006) http://www.nrel.gov/biomass/pdfs/39436.pdf
Biofuels, in Order of Maturity, p2 of 2
FUEL
SOURCE
BENEFITS
STATUS
Pyrolysis
Liquids
Lignocellulosic
biomass
Can utilize waste products
Potential source of aromatics
and phenols
Several commercial
facilities produce
energy and chemicals
Syngas Liquids
Various
biomasses
Can utilize waste products
Can be integrated with fossil
fuel sources (e.g., coal)
High quality fuel
Commercially
demonstrated a large
scale using fossil fuels;
biomass projects
underway
Biodiesel or jet
fuel
Microalgae
High yield per acre
Could be integrated with CO2
capture and reuse
Demonstrated at pilot
scale in 1990s. Many
start-ups currently
underway
Hydrocarbons
(designer fuels)
Biomass
carbohydrates
Generate synthetic copies of
current petroleum derived
feedstocks
Laboratory-scale
research
Adopted from NREL (2006) http://www.nrel.gov/biomass/pdfs/39436.pdf
Ethanol (EtOH)

Chemical Composition




OH
Also known as ethyl alcohol or grain alcohol
2 types:



CH3CH2OH or (C2H6O)
Ethanol is ethanol – source independent
Biologic: conversion of starches to sugar followed by
fermentation of sugar with yeast
Synthetic: acid catalyzed hydration of ethylene
Blending


Currently used as a additive (10% max) to improve
performance (octane) of gasoline
Internal combustion engines must be designed to
accommodate ethanol content >10%
Ethanol Sources
Most common sources are plants with high sugar
or starch content (e.g., corn, beets, cane, potatoes)
 Sources with more complex cellular structures
(e.g., wood, grass, stalks) require more effort to
extract available sugars (cellulosic ethanol)

Biodiesel or
FAME (Fatty Acid Methyl Ester)

Chemical composition




Similar to petroleum diesel fuel in structure (straight
chain) and number of carbon atoms (10 to 20)
Differs in that it is oxygenated and has a small number
of double bonds
Fuel characteristics will vary slightly depending upon
source
Blending



Completely miscible with diesel fuel
Used as an additive (5% max) to increase cetane and
improve performance of diesel
Internal combustion engines must be designed to
accommodate fuels with FAME content >5%
Biodiesel Sources

Plant oils







Soybean
Palm
Rice
Cottonseed
Rapeseed (canola)
Waste oils (plant and animal)
Algae – recent interest because




High amounts of oil
Minimal competition with food crops and crop land
Can be grown on land with low potential for CO2 sequestration
(e.g. deserts)
Does not necessarily require fresh water
Biomass to Liquids (BTL)
via Gasification




Solid or solid/liquid biomass is converted to gas at
high temperatures in the presence of small
amounts of oxygen
Main objective is to transfer the maximum amount
of chemical energy within the feedstock to the
gaseous fraction by producing a high yield of low
molecular weight products (high H:C)
The resulting gas is “conditioned” to produce
synthesis gas (syngas)
Syngas is then converted to liquid fuel via the
Fischer-Tropsch process
30
Dry tons/(acre·yr)
Productivity
High-Productivity Feedstocks
20
3.4
Corn grain
Sweet sorghum
Energy cane
Sweet Sorghum
Grows in ~35 US states
Energy Cane
Energy Cane
High Agricultural Income
$/(acre·yr)
Gross Income
1090
730
340
Corn grain
($2.40/bu)
Sweet sorghum
($40/tonne)
Energy cane
($40/tonne)
Low Environmental Impact
Environmental
cost per
unit of biomass
Water
Fertilizer
Pesticides
Herbicides
Soil erosion
Corn
Grain
High
High
High
High
High
Sweet
Sorghum
Energy
Cane
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Ideal Process Properties
No sterility
No genetically modified organisms (GMOs)
Adaptable
No pure cultures
Low capital
No enzymes
High product yields
No vitamin addition
Co-products not required
Fuel Properties
Ethanol
MTBE
Mixed
Alcohols
Octane
high
high
high
Volatility
high
low
low
no
yes
yes
Energy content
low
high
high
Heat of vaporization
high
low
low
no
yes
no
Pipeline shipping
Ground water damage
MixAlco Process
Mixed
Alcohol
Fuels
Carboxylate
Salts
Biomass
Pretreat
Ferment
Dewater
Thermal
Conversion
Mixed
Ketones
Hydrogenate
Lime
Lime Kiln
Calcium Carbonate
Hydrogen
Storage + Pretreatment
+ Fermentation
Tarp Cover
Air
Biomass + Lime + Calcium Carbonate
Gravel
Dewatering
Mixed
Alcohol
Fuels
Carboxylate
Salts
Biomass
Pretreat
Ferment
Dewater
Thermal
Conversion
Mixed
Ketones
Hydrogenate
Lime
Lime Kiln
Calcium Carbonate
Hydrogen
Vapor-Compression Dewatering
Compressor
Work
Salt
Solution
(Fermentor
Broth)
Distilled Water
Filter
Salt Crystals
Effect of Feedstock Cost
(800 tonne/h, 15% ROI)
Alcohol Selling Price ($/gal)
1.00
0.80
0.60
0.40
0.20
0.00
-40
-20
0
Biomass Cost ($/tonne)
20
40
Centralized Processing
15.3 mi
50% of area
planted
How do we increase
engine efficiency?
hybrids (2 X)
• Better engines (2– 4 X)
• Electric
Meeting US gasoline needs by
growing energy cane in Brazil
1×
2× 3×
Meeting US gasoline needs by growing
sweet sorghum in United States
1×
2× 3×
Conclusion
•
•
•
•
•
•
•
•
•
Reduce wastes
Cleaner air
New agricultural markets
Energy security
Improve balance of payments
Address global warming
Address energy shortage
More flexible international relations
Benefit developing nations