Life Cycle Assessment of Integrated Biorefinery-

Cropping Systems: All Biomass is Local

Seungdo Kim and Bruce E. Dale

Michigan State UniversityJune 24 - 25, 2004June 24 - 25, 2004Arlington, VirginiaArlington, 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 vs Petroleum

020406080

100120140160180

5 10 15 20 25

Cost of oil, $/barrel

Cos

t of

bio

mas

s, $

/ton Weight only

Energy content

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

•Fuels

•Chemicals, etc.

•Monomers

•Lubricants

•Polymers

•Feeds & Foods

•Electricity

•Fertilizer

•Steam

Plant RawPlant RawMaterialMaterial

Pre-Pre-processingprocessing

Final Final ProcessingProcessing

Functional Functional UnitUnit

Recycle or Recycle or DisposalDisposal

Crop Residues

Oilseeds

Sugar Crops

Woody & Herbaceous

Crops

Grains

Protein

Oil

Lignin

Ash

Carbohydrates

Syngas

Products to Replace

Petroleum Based or

PetroleumDependentProducts

Recycledwithin

Product System

orto OtherProduct 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 AgriculturalAgricultural

processprocess BiorefineryBiorefinery ProductsProducts UseUse

Corn grain

Corn stover

Corn grain

Wet milling

Corn stoverprocess

Wet milling

PHA fermentation& recovery

•Corn oil•Corn gluten meal•Corn gluten feed

•Ethanol•Electricity

•PHA

Liquid fuel

Edible oil

Animal feed

Export to power grid

Polymer

If applicable

•Ethanol

•Corn oil•Corn gluten meal•Corn gluten feed

Corn stoverCorn stover

process

•PHA

If applicable

Ethanol production systemEthanol production system

PHA production systemPHA production system

•Electricity

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

Corn oil

Corn grainCorn gluten meal

Corn gluten feed

PHA

Soybean oil

Conventional polymer

Soybean milling Soybean culture

Corn culture

Polymer production

ProductsProducts Alternative product systemsAlternative product systems

Crude oil

Nitrogen in urea Ammonia Natural gas

Driving by E10 fueledvehicle

Driving by gasolinefueled vehicle

Crude oilGasoline

Ethanol production systemEthanol production system

PHA production systemPHA production system

Surplus electricity Electricity Coal-fired power plant Coal

Coproduct systems in both production systemsCoproduct systems in both production systems

Primary Products from Biorefineries

Unit CC CC50 CwCo70

Ethanol production

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

Distance driven by an E10-fueled vehicle

103 miles acre-1 year-1 79 110 129

PHA production

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

Electricity exported MWh acre-1 year-1 - 0.32 0.47

Crude Oil Consumption

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

CC CC50 CwCo70

Cropping system

Cru

de

oil

[lb

ac

re -1

ye

ar-1

]

Ethanol productionsystem

PHA productionsystem

Negative environmental impact represents an environmental credit. Negative environmental impact represents an environmental credit.

Nonrenewable Energy

-70

-60

-50

-40

-30

-20

-10

0

CC CC50 CwCo70

Cropping system

No

nre

new

able

en

erg

y [M

M

Btu

acr

e -1

yea

r-1]

Ethanol productionsystem

PHA productionsystem

Global Warming

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

2000

4000

CC CC50 CwCo70

Cropping system

Glo

bal

war

min

g [

MM

lb

CO

2 e

q.

acre

-1 y

ear-1

]

Ethanol productionsystem

PHA productionsystem

Eco-efficiency Definition

ratioimpacttalEnvironmen

addedvalueEconomicefficiencyEco

fuel&materialrawofCost

productsofvalueMarketaddedvalueEconomic

credittalEnvironmen

impacttalEnvironmenratioimpacttalEnvironmen

A practice with a greater eco-efficiency would be more sustainable.

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)

Global warming(1,0)

X: Fraction of corn grain utilized for producing ethanolY: Fraction of corn stover utilized for producing ethanol

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