Life Cycle Assessment of
Integrated BiorefineryCropping Systems:
All Biomass is Local
Seungdo Kim and Bruce E. Dale
Michigan State University
June 24 - 25, 2004
Arlington, Virginia
Biocommodities: A New Partnership between
the U. S. Chemical Industry & U. S. Agriculture?
Raw Materials + Processing =
Value-Added Products
Processing by Physical, Thermal, Chemical and/or
Biological Means
Cost to make mature, commodity products depends
on:
1) Raw material cost (60-70% of total)
2) Processing cost (the remainder)
Features of a Mature Biocommodity Industry:
Some Lessons from Petrocommodities
• Yield of product(s) is the dominant techno-economic
factor
• Raw material cost & supply ultimately determines
potential scale of industry
• Product slate diversifies over time
• Very broad plant raw material base (but
compositionally materials are quite similar)
• Agricultural productivity (“food vs. fuel”) is the
ultimate constraint on production
• “Sustainability” is the dominant socio-environmental
constraint: soil fertility first of all
• Industry will be influenced to an unprecedented
degree by local issues: “all biomass is local”
Cost of biomass, $/ton
Cost of Biomass vs Petroleum
180
160
140
120
100
80
60
40
20
0
Weight only
Energy content
5
10
15
Cost of oil, $/barrel
20
25
Some Perspectives and Premises on Agriculture
as a Producer & Consumer of Energy
• Inexpensive plant raw materials will catalyze the very
large scale production of fuels from “biomass”
• “Consumer of energy” is straightforward
• “Producer of energy” not so straightforward
– Except for windpower, agriculture does not “produce” energy
– Conversion facility (“biorefinery) makes the energy products
• Systems questions addressed by “life cycle analysis”
(LCA) integrating agricultural sector with biorefinery
• Some critical issues:
– all BTU are not created equal– “exchange rate” 3
BTU coal = 1 BTU electricity
– all BTU do not have the same strategic importance
– “All Biomass is Local” climate, soils, crops
What Are Life Cycle (LCA) Models?
• Full system studies of material/energy inputs & outputs
of both products & processes
• Inventory environmental impacts of products &
processes (many possible impacts, select “key” ones)
• Objectives:
– Benchmark, evaluate & improve environmental
footprint
– Compare with competition
– Comply with regulations or consumer expectations?
• Methods for doing LCA studies are not universally
agreed upon—allocation issues in particular are both
important and somewhat controversial
Some Life Cycle Analysis Standards:
In Plain English
• Use the most recent data possible
• Make it easy for others to check your data
and methods= transparency
• Set clear system boundaries: what exactly
are we comparing?
• Multi-product systems must allocate
environmental costs among all products-(no
environmental burdens assigned to wastes)
• Perform sensitivity analysis: how much do
results vary if assumptions or data change?
Our Approach to Life Cycle Analysis
• Be very specific about the location and particular
cropping systems that support the biorefinery
• Be very clear and careful about system boundaries
• Defend/explain allocation of environmental burdens
among products-including energy products
• Formulate, ask and answer specific questions
• Explore complete system (Industrial Ecology model)
when possible
• Remember: “All Biomass Is Local”
ALL BIOMASS IS LOCAL
Advantages of a Local Focus for
Biobased Products LCA
• Reduces opportunities for agenda-driven
manipulation of data
• Studies are more relevant to the actual situation
faced by investors & innovators
• Better application of agricultural & environmental
policy instruments
• Improves selection of crops & cropping systems for
local biorefineries
• Illuminates opportunities for system integration &
“waste” utilization
Objectives
• Environmental performance of biobased
products
– Integrated biorefinery-cropping systems
• Ethanol
• Polyhydroxyalkanoates (PHA)
• Eco-efficiency analysis
– Ethanol and PHA are produced from the
same unit of arable land
Concept of Biorefinery
Plant Raw
Material
Grains
Crop
Residues
Preprocessing
Final
Processing
Carbohydrates
Protein
•Chemicals, etc.
•Polymers
•Feeds & Foods
•Monomers
Oilseeds
Syngas
Woody &
Herbaceous
Crops
Recycle or
Disposal
•Fuels
Oil
Sugar
Crops
Functional
Unit
•Lubricants
• Electricity
Lignin
Ash
• Steam
• Fertilizer
Products to
Replace
Petroleum
Based or
Petroleum
Dependent
Products
Recycled
within
Product
System
or
to Other
Product
Systems
Compost pile
or
Landfill
Cropping Systems
• Cropping site: Washington County, Illinois
• No-tillage practice
• Continuous cultivation (No winter cover crop)
– 0 % of corn stover removed: CC
– Average 50 % of corn stover removed: CC50
• Effect of winter cover crop
– Wheat and oat as winter cover crops after corn
cultivation with 70 % corn stover removal: CwCo
70
Products in a Biorefinery
Agricultural
process
Biorefinery
Corn grain
Wet milling
If applicable
Corn stover
Corn stover
process
Products
•Ethanol
•Corn oil
•Corn gluten meal
•Corn gluten feed
Wet milling
PHA fermentation
& recovery
•Ethanol
•Electricity
•Corn oil
•Corn gluten meal
•Corn gluten feed
Corn stover
process
Animal feed
Export to power grid
•PHA
If applicable
Corn stover
Liquid fuel
Edible oil
Ethanol production system
Corn grain
Use
Polymer
•PHA
•Electricity
PHA production system
Life Cycle Assessment Study
• Functional Unit: One acre of farmland
• Allocation: System expansion approach
– Avoided product systems
•
•
•
•
•
Gasoline fueled vehicle for ethanol fueled vehicle
Polystyrene for PHA
Corn grain and nitrogen in urea for corn gluten meal/corn gluten feed
Soybean oil for corn oil
Electricity generated from a coal-fired power plant for surplus electricity
• Inventory data sources: Literature
– Soil organic carbon and nitrogen dynamics: DAYCENT model
• Impact assessment: TRACI model (EPA)
– Crude oil consumption, Nonrenewable energy, Global warming
Primary Assumptions
• Ethanol yield
– From corn grain: 2.55 gal/bushel (via wet milling)
– From corn stover: 89.7 gal/dry ton
• Ethanol is used as an E10 fuel in a compact
passenger vehicle
– a mixture of 10 % ethanol and 90 % gasoline by
volume
• PHA yield
– From corn grain: 10.9 lb of PHA/bushel
– From corn stover : 294 lb of PHA/dry ton
• PHA replaces an equivalent mass of
petroleum based polymer.
Allocation Procedures
Products
Alternative product systems
Driving by E10 fueled
vehicle
Driving by gasoline
fueled vehicle
Gasoline
Crude oil
Ethanol production system
PHA
Conventional
polymer
Polymer production
Crude oil
PHA production system
Surplus electricity
Electricity
Coal-fired power plant
Coal
Corn oil
Soybean oil
Soybean milling
Soybean culture
Corn gluten meal
Corn grain
Corn gluten feed
Nitrogen in urea
Corn culture
Ammonia
Coproduct systems in both production systems
Natural gas
Primary Products from Biorefineries
Unit
CC
CC50
CwCo70
Ethanol from corn grain (A)
gallon acre-1 year-1
346
342
357
Ethanol from corn stover (B)
gallon acre-1 year-1
-
143
209
Total ethanol (A+B)
gallon acre-1 year-1
346
511
565
Electricity exported
MWh acre-1 year-1
-
0.94
1.4
103 miles acre-1 year-1
79
110
129
PHA from corn grain (A)
lb acre -1 year-1
1,484
1,466
1,530
PHA from corn stover (B)
lb acre -1 year-1
469
685
Total PHA (A+B)
lb acre -1 year-1
1,484
1,935
2,215
MWh acre-1 year-1
-
0.32
0.47
Ethanol production
Distance driven by an E10fueled vehicle
PHA production
Electricity exported
Crude oil [lb acre
-1
year-1]
Crude Oil Consumption
0
-500
-1000
Ethanol production
system
-1500
PHA production
system
-2000
-2500
-3000
-3500
CC
CC50
CwCo70
Cropping system
Negative environmental impact represents an environmental credit.
Nonrenewable energy [MM
-1
-1
Btu acre year ]
Nonrenewable Energy
0
-10
-20
Ethanol production
system
-30
PHA production
system
-40
-50
-60
-70
CC
CC50
Cropping system
CwCo70
Global warming [MM lb
-1
-1
CO2 eq. acre year ]
Global Warming
4000
2000
0
-2000
Ethanol production
system
-4000
PHA production
system
-6000
-8000
-10000
-12000
-14000
CC
CC50
CwCo70
Cropping system
Eco-efficiency Definition
Economic value added
Eco  efficiency 
Environmen tal impact ratio
A practice with a greater eco-efficiency
would be more sustainable.
Market value of products
Economic value added 
Cost of raw material & fuel
Environmen tal impact
Environmen tal impact ratio 
Environmen tal credit
Eco-efficiency Analysis
• Suppose ethanol and PHA are produced together
from the same unit of arable land.
Crude oil used
(0,0)
Nonrenewable energy
(0,0)
X: Fraction of corn grain utilized for producing ethanol
Y: Fraction of corn stover utilized for producing ethanol
Global warming
(1,0)
Conclusions
• Cropping systems play an important role in the
environmental performance of biobased products.
• Utilizing corn stover combined with winter cover crop
production (CwCo70) is the most environmentally
favorable cropping system studied here.
• Both ethanol and PHA produced in CwCo70 provide
environmental credits in terms of crude oil use,
nonrenewable energy and global warming.
• Considering only “sustainable utilization” of biomass
(i.e., at maximum eco-efficiency), the fractions of corn
grain and corn stover utilized for producing ethanol
vary with the impact categories.
• Sustainable, energy-producing approaches are
available to produce commodity chemicals & fuels
from plant raw materials