Life Cycle Assessment (LCA)

of

Ethanol Fuel from Willow Biomass

CORRIM

Mohit Rastogi, Rick Gustafson, Joyce Cooper, Timothy Volk,

Jesse Caputo, Leonard Johnson, Maureen Puettmann

CORRIM Biofuels Research

• Gasification

• Pyrolysis

• Bioconversion

Ethanol

Pyrolysis Oil

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.

Scope

Biomass transport

Biochemical conversion

(core process)

Fuel distribution Fuel use

Biomass production

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

Willow Biomass Production Cycle

Three-year old after

coppice

One-year old after

coppice

Coppice

First year growth

Site Preparation

Planting

Early spring after coppicing

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

Biochemical conversion process

SO2 Steam Lime H2SO4 Gypsum Nutrition

Enzyme

Steam

Burner/Boiler/ Turbogenerator

Utilities

Feedstock storage &

Handling

Storage

Saccharification &

Co-Fermentation

Product purification Wastewater

Treatment

Pretreatment and

Conditioning

Feedstock (Willow)

Nutrition Vent

Steam

Electricity

Boiler blowdown

Anaerobic, CH4

Still solids and evaporator syrup Ethanol

Broth

Excess condensate

Recycle condensate

Cooling tower blowdownn

Recycle water

Steam

(34 MGPY)

(Excess electricity:

~ 20 MW)

(462,000 ton/year)

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)

Methodology

SimaPro LCA

model (by UW)

Biomass

growth/yield model

(by CORRIM)

ASPEN process model

(by NREL and UW)

GREET vehicle-use

model (by ANL)

RESULTS

Global Warming Potential (GWP)

Water use

Fossil energy use

Other Impacts

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

Acknowledgement The support for this research from the US Forest Service and

the Department of Energy is greatly appreciated.

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”

Chemicals production

Nutrients production

Harvesting Chipping

Feedstock handling Pretreatment &

Conditioning

conditioning

Distillation & Dehydration Saccharification &

Co-fermentation

Enzyme production

Storage

Energy production

Wastewater treatment

Utilities Electricity Steam

Landfill

Landfill

S1: Willow production and collection subsystem

S2: Ethanol biorefinery subsystem

S3: Ethanol distribution

subsystem

Water

CO2

Sludge & biogas

Ethanol

Sy

rup

& s

oli

d r

esid

ues

Lubricants production

Ash

Gypsum

Offgas CO2 Combustion

emissions

Willow chips

Avoided US mix

electricity production

Planting

Fertilizers production

Fossil fuels production

Pesticides production

Agrochemical

emissions

Excess electricity

Fossil fuels production

S4: Ethanol use subsystem

SYSTEM

BOUNDARIES

Contribution analysis for Ethanol (Other Impacts)