This document presents the results of a life cycle assessment of ethanol fuel produced from willow biomass. The study evaluated the fuel's impact on global warming potential, fossil energy use, water use, and other environmental impacts. It found that willow ethanol production is near carbon neutral due to avoided emissions from coal and oil displacement. However, water usage for the bioconversion process was substantial. The impacts on acidification were greater for ethanol than gasoline, while impacts on toxicity were greater for gasoline production. The study used models to analyze impacts across the full fuel lifecycle, from biomass growth and processing to fuel distribution and combustion.

1. Life Cycle Assessment (LCA)
of
Ethanol Fuel from Willow Biomass
Mohit Rastogi, Rick Gustafson, Joyce Cooper, Timothy Volk,
Jesse Caputo, Leonard Johnson, Maureen Puettmann
CORRIM

2. CORRIM Biofuels Research
• Pyrolysis Pyrolysis Oil
• Gasification
Ethanol
• Bioconversion

3. Research objectives
 Perform LCA on Willow-based Ethanol fuel to
evaluate the following:
• Global warming potential (GWP)
• Fossil energy use
• Water use
• Other impacts such, toxicity, acidification, and
photochemical-oxidants formation
 To improve the environmental fuel’s performance
with contributional analysis.

4. Scope
Biomass production Biomass transport
Biochemical conversion
(core process)
Fuel distribution
Fuel use

5. Key assumptions
 Land use does not cause direct or indirect greenhouse gas
emissions.
• Direct emissions for site preparation are offset by below ground
accumulation.
• Use of idle land minimizes indirect land use
 Feedstock and final products are transported 100 miles (average
round trip).
 Electricity from biorefinery displaces production from US
national grid – no regional specificity.
 Gypsum is disposed of as a solid by-product
 Comparisons with gasoline are on an equivalent energy (MJ) basis
 System expansion used to model impacts of co-products

6. Willow Biomass Production Cycle
Three-year old after
Site Preparation coppice
Planting
One-year old after
coppice
Coppice
First year growth
Early spring after coppicing

7. Willow Production & Harvesting
 The largest inputs in terms of
energy and dollars are:
 harvesting
 site preparation and establishment
 N fertilizer inputs
 Crop is not irrigated
 Willow harvested using single pass
cut and chip system
 Chips are blown into a forage or
dump wagon and sent right to the
biorefinery

8. Biochemical conversion process
SO2 Steam Lime H2SO4 Gypsum Nutrition
(462,000 ton/year)
Enzyme
Feedstock
(Willow)
Feedstock storage & Pretreatment and Saccharification &
Handling Conditioning
Co-Fermentation
Recycle water
Recycle condensate
Steam
Steam Broth
Nutrition Vent
Excess condensate
Wastewater Product purification
Treatment
Still solids and evaporator syrup
Ethanol (34 MGPY)
Cooling Boiler Steam
tower blowdown Burner/Boiler/ Storage
blowdown Turbogenerator
n Anaerobic, CH4
Utilities (Excess electricity:
Electricity
~ 20 MW)

9. Process area Process Yields Value Unit
Pretreatment
Xylan to Xylose Yield 75 %
Mannan to Mannose Yield 61 %
Galactan to Galactose Yield 61 %
Arabinan to Arabinose Yield 75 %
Saccharification
Cellulose to Glucose Yield 75 %
Co-Fermentation
Glucose to Ethanol Yield 95 %
Xylose to Ethanol Yield 85 %
Arabinose to Ethanol Yield 85 %
Mannose to Ethanol Yield 95 %
Galactose to Ethanol Yield 95 %
Contamination Loss 3 %
Overall Yield = 74 gallons ethanol/ton (OD biomass)

10. Methodology
Biomass SimaPro LCA
growth/yield model GREET vehicle-use
(by CORRIM) model (by UW) model (by ANL)
ASPEN process model
(by NREL and UW)

11. RESULTS

12. Global Warming Potential (GWP)

13. Water use

14. Fossil energy use

15. Other Impacts

16. Conclusions
 Production of ethanol from willow plantations is near carbon
neutral
• Displacement of power production from coal and oil
• No accounting for indirect land use
 Water usage for bioconversion is substantial and will need to be
addressed
 Other impacts are mixed –much greater for ethanol (acidification)
for some and greater for petroleum(toxicity) for others

17. Acknowledgement
The support for this research from the US Forest Service and
the Department of Energy is greatly appreciated.

18. Willow – excellent feedstock for
bioconversion processes
 Example SRWC (Short
Rotation Woody Crop)
 Rapid early growth rates
 Ease of vegetative
propagation from dormant
cuttings.
 Ability to re-sprout after
multiple harvests.
 Suitable for cultivation on
low quality land.
 Broad genetic diversity
 Good “sugar release”

19. Agrochemical Combustion
CO2 Offgas
emissions emissions
SYSTEM
BOUNDARIES
Fossil fuels production
S1: Willow production and collection subsystem
Lubricants production
Planting Harvesting Chipping
Fertilizers production
CO2
Pesticides production
S2: Ethanol biorefinery subsystem
Water Willow chips
Gypsum Landfill
Feedstock handling Pretreatment &
Conditioning
Distillation & Dehydration Chemicals production
Syrup & solid residues
Saccharification &
Co-fermentation
Ethanol
Enzyme production
Storage Wastewater treatment
conditioning
Sludge & biogas
Nutrients production
Energy production
Electricity Steam Utilities
Avoided US mix
electricity production
Landfill Excess electricity
Ash
S3: Ethanol distribution S4: Ethanol use subsystem
Fossil fuels production subsystem

20. Contribution analysis for Ethanol
(Other Impacts)