(6) Life-Cycle Analysis of Biofuels with the GREET Model ... · Waste cooking oil Animal fat Sugar Crops for EtOH Sugar cane Sugar beet Sweet sorghum GREET Includes Many Potential

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Life-Cycle Analysis of Biofuels with the GREET Model

Michael Wang

Center for Transportation Research

Argonne National Laboratory

IEA Bioenergy Task 42 Workshop

Chicago, USA, Oct. 4, 2010

The GREET (GGreenhouse gases, RRegulated EEmissions, and EEnergy use in TTransportation) Model

� GREET development has been supported by DOE

since 1995

� GREET and its documents are available at Argonne’s

website at

http://www.transportation.anl.gov/software/GREET/

� The most recent GREET version (GREET 1.8d) was

released in July 2010

� There are over 14,000 GREET registered users

worldwide



� Energy use

� Total energy: fossil energy and renewable energy

• Fossil energy

– Petroleum

– Natural gas

– Coal

• Renewable energy: biomass, nuclear energy, hydro-power, wind power, and solar energy

� Greenhouse gases (GHGs)

� CO2

� CH4

� N2O

� CO2e of the three (with their global warming potentials of 1, 23, and 296, respectively)

� Criteria pollutants

� VOC

� CO

� NOx

� PM10

� PM2.5

� SOx

� They are estimated separately for

• Total (emissions everywhere)

• Urban (a subset of the total)

The GREET Model Estimates Energy Use and Emissions of GHGs and Criteria Pollutants for Fuel Production and Use

3

GREET Includes More Than 100 Fuel

Production Pathways from Various Energy Feedstocks

Petroleum

Conventional

Oil Sands

Petroleum

Conventional

Oil Sands

Compressed Natural Gas

Liquefied Natural Gas

Liquefied Petroleum Gas

Hydrogen

Methanol

Dimethyl Ether

Fischer-Tropsch Diesel

Fischer-Tropsch Naphtha

Fischer-Tropsch Jet Fuel




Hydrogen

Methanol

Dimethyl Ether




Natural Gas

North American

Non-North American

Natural Gas

North American

Non-North American

CoalCoal

SoybeansSoybeans

Gasoline

Diesel


Naphtha

Residual Oil

Jet Fuel

Gasoline

Diesel


Naphtha

Residual Oil

Jet Fuel

Hydrogen

Methanol

Dimethyl Ether



Hydrogen

Methanol

Dimethyl Ether



Biodiesel

Renewable Diesel

Renewable Jet Fuel

Biodiesel

Renewable Diesel

Renewable Jet Fuel

SugarcaneSugarcane

CornCorn

Cellulosic Biomass

Switchgrass

Fast Growing Trees

Crop Residues

Forest Residues

Cellulosic Biomass

Switchgrass

Fast Growing Trees

Crop Residues

Forest Residues

Coke Oven Gas

Petroleum Coke

Nuclear Energy

Coke Oven Gas

Petroleum Coke

Nuclear Energy

Residual Oil

Coal

Natural Gas

Biomass

Other Renewables

Residual Oil

Coal

Natural Gas

Biomass

Other Renewables

Ethanol

Butanol

Ethanol

Butanol

EthanolEthanol

Ethanol

Hydrogen

Methanol

Dimethyl Ether



Ethanol

Hydrogen

Methanol

Dimethyl Ether



ElectricityElectricity

HydrogenHydrogen

The yellow boxes contain the names of the feedstocks and the red boxes contain the names of the fuels that can be

produced from each of those feedstocks.



Hydrogen

Methanol

Dimethyl Ether






Hydrogen

Methanol

Dimethyl Ether




Renewable

Natural Gas

Landfill Gas

Renewable

Natural Gas

Landfill Gas



� Oils for Biodiesel/Renewable

Diesel/Renewable Jet Fuel

�Soybeans

�Rapeseed

�Palm oil

�Jatropha

�Waste cooking oil

�Animal fat

� Oils for Biodiesel/Renewable

Diesel/Renewable Jet Fuel

�Soybeans

�Rapeseed

�Palm oil

�Jatropha

�Waste cooking oil

�Animal fat

� Sugar Crops for EtOH

� Sugar cane

� Sugar beet

� Sweet sorghum

� Sugar Crops for EtOH

� Sugar cane

� Sugar beet

� Sweet sorghum

GREET Includes Many Potential Biofuel Production Pathways

� Starch Crops for EtOH

� Corn

� Wheat

� Cassava

� Sweet potato

� Starch Crops for EtOH

� Corn

� Wheat

� Cassava

� Sweet potato

� Cellulosic Biomass for EtOH

� Corn stover, rice straw, wheat straw

� Forest residues

� Municipal solid waste

� Dedicated energy crops

� Black liquor

� Cellulosic Biomass for EtOH

� Corn stover, rice straw, wheat straw

� Forest residues

� Municipal solid waste

� Dedicated energy crops

� Black liquor

The feedstocks and fuels that are underlined are already included in the GREET model.

� Algae

� Biodiesel

� Renewable diesel

� Algae

� Biodiesel

� Renewable diesel

� Landfill Gas

� CNG/LNG

� Fischer-Tropsch diesel

� Hydrogen

� Methanol

� DME

� Fischer-Tropsch jet fuel

� Landfill Gas

� CNG/LNG


� Hydrogen

� Methanol

� DME


� Cellulosic Biomass via Gasification


� Hydrogen

� Methanol

� DME


� Cellulosic Biomass via Gasification


� Hydrogen

� Methanol

� DME


� Butanol

� Corn

� Sugar beet

� Butanol

� Corn

� Sugar beet

Life-Cycle Analysis System Boundary: Corn to Ethanol

Conventional Animal Feed Production

CO2 in the atmosphere

CO2 via photosynthesis

Energy inputs for farming

Fertilizer

N2O emissions from soil and

water streams

CO2 emissions during fermentation

CO2 emissions from ethanol combustionCarbon in

ethanol Carbon in kernels

Chang

e in so

il

carb

on Effecti

ve vi

a pric

e

signa

lDGS

Direct land use change

Indirect land use changes for other crops and in other

regions



Life-Cycle Analysis System boundary:Switchgrass to Cellulosic Ethanol

Conventional electricity generation

CO2 in the atmosphere

CO2 via photosynthesis

Cellulosic biomass Ethanol

CO2 emissions from ethanol combustion

CO2 emissions during fermentation

Energy inputs for farming

Fertilizer

N2O emissions from soil and

water streams Chang

e in so

il

carb

onEffe

ctive

via

price

signa

l

Lignin

On-site power

generation

Direct land use change Indirect land use

changes for other crops and in other

regions

Life-Cycle Analysis System Boundary: Petroleum to Gasoline

CO2 emissions

Energy Inputs

Recovery

Crude Oil

Energy Inputs Energy Inputs Energy Inputs



The U.S. EPA’s Final Rule for EISA RFS2

� A suite of models (including GREET) were used to conduct biofuel LCAs

Feb. 2010 EISA Target

Corn EtOH -21% -20%

Sugarcane EtOH -61% -50%

Corn Stover EtOH: Bio-Chem -131% -60%

Corn Stover EtOH: Thermo-Chem -93% -60%

Corn Stover FD Diesel -92% -60%

Switchgrass EtOH: Bio-Chem -110% -60%

Switchgrass EtOH: Thermo-Chem -72% -60%

Switchgrass FT Diesel -71% -60%

Soybean Biodiesel -57% -50%

Waste Grease Biodiesel -86% -50%

EPA Estimated Biofuel GHG Changes (30 yr and 0% Discount, Relative to 2005 Gasoline)

California Has Adopted Low-Carbon Fuel Standards (LCFS) in April 2009

� 10% reduction in

carbon intensity of CA

fuel supply pool (in g

CO2e/MJ) by 2020

� GREET was used to

develop fuel-specific

carbon intensities

� Purdue’s GTAP model

was used for land use

simulations

� Fuel carbon intensity

may be adjusted with

vehicle efficiency

Fuel Direct

Emissions

Land Use or

other effects

Total

CA Gasoline 95.86 0 95.86

Midwest Corn EtOH 69.40 30 99.40

CA Corn EtOH, wet

DGS

50.70 30 80.70

Sugarcane EtOH 27.40 46 73.40

CA Electricity 124.10 0 41.37

NG-Based H2 142.20 0 61.83

Adopted Carbon Intensities for Selected Fuels (g

CO2e/MJ)



Key Issues Affecting Biofuel WTW Results

� Continued technology advancements� Agricultural farming: continued crop yield increase and resultant reduction of

energy and chemical inputs per unit of yield

� Energy use in ethanol plants: reduction in process fuel use and switch of process

fuel types

� Methods of estimating emission credits of co-products

of ethanol

� Direct and indirect land use changes and resulted GHG

emissions

� Life-cycle analysis methodologies� Attributional LCA

� Consequential LCA

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Dry Mill Wet Mill Average

Historical Ethanol Plant Energy Use: Btu/Gallon

Energy Use in U.S. Corn Ethanol Plants Has Reduced Significantly in the Past 30 Years



0 .0 0

0 .2 0

0 .4 0

0 .6 0

0 .8 0

1 .0 0

1 .2 0

1 .4 0

1 .6 0

1 .8 0

Rate of Fertilizer Use (lb/bushel)

Year

Nitroge n P 2 O 5 K 2 O

Fertilizer Use in U.S. Corn Farming Has Reduced Significantly in the Past 40 Years

Most Recent Studies Show Positive Net Energy Balance for Corn Ethanol

Energy balance here is defined as Btu content a gallon of ethanol minus fossil energy used to produce a gallon of ethanol



Co-Product Methods: Benefits and Issues � Displacement method

– Data intensive: need detailed understanding of the displaced product sector

– Dynamic results: subject to change based on economic and market modifications

� Allocation methods: based on mass, energy, or market revenue

– Easy to use

– Frequent updates not required for mature industry, e.g. petroleum refineries

– Mass based allocation: not applicable for certain cases

– Energy based allocation: results not entirely accurate, when coproducts are used in

non-fuel applications

– Market revenue based allocation: subject to price variation

� Process energy use approach

– Detailed engineering analysis is needed

– Upstream burdens still need allocation based on mass, energy, or market revenue

Choice of Co-Product Methods Can Have Significant LCA Effects

-120,000

-80,000

-40,000

0

40,000

80,000

C-E

1

C-E

2

C-E

3

C-E

4

C-E

5

G-E

1

G-E

2

G-E

3

S-B

D1

S-B

D2

S-B

D3

S-B

D4

S-R

D1

S-R

D2

S-R

D3

S-R

D4

S-R

D5

. Gasoline . Diesel . Corn-EtOH . Switchgrass - EtOH . Biodiesel . Renewable Diesel .

GH

G E

mis

sion

s (g

/mm

Btu

)

.

PTW

WTP

WTW

In Wang et al. (2010)



Key Steps to Address GHG Emissions of Potential Land Use Changes by Large-Scale Biofuel Production

� Simulations of potential land use changes

� Significant efforts have been made in the past 16 months to improve

existing computational general equilibrium (CGE) models

� More efforts are still required

� Carbon profiles of major land types

� Both above-ground biomass and soil carbon are being considered

� Of the available data sources, some are very detailed (e.g., the Century

model) but others are very coarse (e.g., IPCC)

� There are mismatches between CGE simulated land types and land types in

available carbon databases

� Soil depth for soil carbon could be a major issues when energy crops are to

be simulated

U.S. Efforts on Modeling LUCs of Biofuel Production

� Searchinger et al. with FAPRI for corn ethanol

� CARB/UCB/Purdue with GTAP for corn ethanol

� EPA/Texas A&M/Iowa State U. with FASOM

and FAPRI for corn ethanol, biodiesel,

sugarcane ethanol, and cellulosic ethanol

� DOE/ANL/ORNL/Purdue with GTAP for corn

ethanol and cellulosic ethanol

� Others have been applying models to examine

LUCs



Land Use Change Simulated for US Corn Ethanol Production

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Searchinger et al.

2008

EPA 2010b CARB 2009 Hertel et al. 2010 Tyner et al. 2010:

a

Tyner et al. 2010:

b

Tyner et al. 2010:

c

Acr

es/

10

00

Eth

an

ol G

allo

ns

Effects of several critical factors in CGE models:

� Available land types

� Yield responses to price increase

� Animal feed modeling

� Growth in both demand and supply

Share of GHG Emissions for Corn Ethanol (total of 5,655 g/gal EtOH)



GHG Emissions of Corn Ethanol Vary Considerably Among Process Fuels in Plants; Cellulosic Ethanol Consistently Achieve Large Reductions

From Wang et al. (2007)

GHG Emission Reductions By Ethanol Relative to Gasoline

Argonne’s Effort on Life Cycle Analysis of Algae Biofuels Production

Algae GrowthHarvesting &

Dewatering

Bio-oil

Extraction &

Separation

Spent

Biomass

Utilization

Bio-oil

Upgrading

Biofuel

WaterWater

Inoculants

Nutrients

CO2

Water

Biogas

Nutrients



Specific Activities Currently Under Way at Argonne� Collect information for algae nutrients:

– Growth recipes (N, P, K, water conditioning, etc)

– Energy inputs and emission outputs for manufacturing and transport to algal

site.

� CO2 capture and transportation options:

– Energy inputs and emission outputs, costs

– CO2 from concentrated flue gas over long distance vs. raw flue gas at short

distance

� Alternative process units for algal growth:

– Raceway pond vs. photobioreactor (PBR)

– Options complexity adds up to complexity to interface with GREET pathway

platform

� Challenge: limited amount of detailed quantitative information is openly

available:

– Intellectual property, trade secrets

– Unknown details, suppositions

Outstanding LCA Issues� Purpose of LCAs and their models has been evolving over the past 30 years

� System boundary of LCAs has been a moving target

� Consistency vs. intuition (an issue of resource availability)

� Research vs. policy development

� Aggregate effects vs. attribution (and responsibility):

� Attributional LCAs: based on engineering principles and processes

� Consequential LCAs: based on economic interactions in a country or in the world

� Implications of the two approaches:

� Sectoral vs. economy-wide climate policies

� Direct actions vs. indirect effects from two points of view: regulatory agencies and regulated parties

� Uncertainties of biofuel LCAs

� Systematic uncertainties: LCA methodologies, system boundary, etc.

� Technical uncertainties: parametric assumptions

� Sensitivity analyses

� Stochastic analysis

� Transparency of LCA methodologies and key assumptions

� Scope of LCAs

� Average vs. marginal analysis

� Industry vs. facility analysis



Biofuel Water Sustainability Analysis

How Much Water Is Consumed To Drive A Passenger Car For A Mile?

Corn Ethanol Cellulosic EthanolPetroleum Gasoline

Regions USDA 5 USDA 6 USDA 7 Native habitat PADD II, III, V

Production process

Dry milling Thermochemical Biochemical Vary

Share of fuel production

52% 14% 30% 81%

Share of feedstock production

52% 16% 20% 90%

gal water/gal gas. eq.

15 26 492 3 9* 15 3 - 7

gal water/mile travelled

0.6 1.1 21.0 0.1 0.4 0.6 0.1 – 0.3

* Advanced biochemical process



A Critical Issue is Water Quality Impact

Examine Options to Manage and Efficient Use of Water Resource for Biofuel Production

Types of biofuel feedstock

Grains

Agri. residue

Dedicated energy crops

Land use changes

Pasture land

Marginal land

Crop rotation

Agricultural practices

Management programs

Watershed environmental loading

Soil erosion

Surface water

Ground water

Industrial discharge

Municipal discharge

Fertilizer run-off and leakage

Documents

(6) Life-Cycle Analysis of Biofuels with the GREET Model ... · Waste cooking oil Animal fat Sugar Crops for EtOH Sugar cane Sugar beet Sweet sorghum GREET Includes Many Potential