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Fuel-Cycle Energy and Greenhouse
Emission Impacts of Fuel Ethanol
Michael WangCenter for Transportation Research
Argonne National Laboratory
Presentation at EPA Cincinnati
Cincinnati, Ohio, May 8, 2003
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Cycles for Vehicle/Fuel Systems
The Illustration is for Petroleum-Based Fuels
Vehicle Cycle
Fuel Cycle
Well to Pump
P um p t o
Wh e el s
WTP: well-to-pump
PTW: pump-to-wheels
WTW: well-to-wheels (WTP + PTW)
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The GREET (G reenhouse gases,
R egulated E missions, and E nergy
use in T ransportation) Model GREET includes emissions of greenhouse gases
CO2, CH4, and N2O
VOC, CO, and NOx as optional GHGs
GREET estimates emissions of five criteria pollutants
VOC, CO, NOx, PM10, and Sox
Total and urban emissions separately GREET separates energy use into
All energy sources
Fossil fuels (petroleum, natural gas, and coal)
Petroleum
The GREET model and Its documents are available at
http://greet.anl.gov; there are about 800 registered GREET users
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U.S. Fuel Ethanol Production
and Use Have Increased Steadily
Source: Renewable Fuels Association’s
2003 Ethanol Industry Outlook Report.
In 2002, the U.S. used
2.1 billion gallons of fuel ethanol
Type Purpose Mil. Gal.
FRFG Oxygenate (E6-E10) 700
F.Winter Oxy. Fuels Oxygenate (E10) 250
MN Oxy. Fuels Oxygenate (E10) 250
Conv. Gasoline Octane/Extender 900
Total 2,100
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Energy Effects of Fuel Ethanol
Have Been Subject to Debate
Some studies, especially those completed between late
1980s and early 1990s, concluded negative energy
balance value of ethanol
Those past studies basically examined energy use of
producing ethanol
Though self evaluation of ethanol’s energy balance is easy
to understand, it may not be useful to fully understand trueenergy benefits of fuel ethanol
A more complete way is to compare fuel ethanol with the
fuels to be displaced by ethanol (i.e., gasoline)
The GREET model has been applied to conduct a
comparative analysis between ethanol and gasoline
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Emission Effects of Fuel Ethanol Were
Not Addressed on the Fuel-Cycle Basis
Past emission studies focused mainly on ethanol’sevaporative emissions and its effects on vehicle tailpipe
emissions
Well-to-pump emissions were identified for ethanol andgasoline only in a piece-meal way
Petroleum refinery emissions
Ethanol plant emissions GHG emissions were simply ignored in some debatable
studies
Emissions of fuel ethanol need to be evaluated in aholistic and comparative way
For criteria pollutant emissions, future emission controls
for WTP and vehicle activities are important
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GREET Calculation Logic for Production Activities
Inputs
EmissionFactors
CombustionTech. Shares
Energy
Efficiencies
FacilityLocation Shares
Fuel TypeShares
Energy Use byFuel Type
TotalEmissions
UrbanEmissions
Calculations
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GREET Calculation Logic
for Transportation Activities
Energy Intensity(Btu/ton-mile)
Energy Intensity(Btu/ton-mile)
Transport
Distance (mi.)
Transport
Distance (mi.)
Energy Consumption
(Btu/mmBtu Fuel Transported)
Emission Factors
(g/mmBtu fuel burned)
Emission Factors
(g/mmBtu fuel burned)
Share of Process Fuels
Emissions by Mode
(g/mmBtu Fuel
Transported)
Mode ShareMode Share
Energy Use by Mode
(Btu/mmBtu Fuel Transported)
Emissions (g/mmBtu
Fuel Transported)
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GREET Is Designed to
Conduct Stochastic Simulations
Distribution-Based Inputs Generate Distribution-Based Outputs
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Petroleum Refining Is the Key
Energy Conversion Step for Gasoline
Petroleum Recovery (97%)
Gasoline at Refueling Stations
Petroleum Transport
and Storage (99%)
Transport, Storage, and
Distribution of Gasoline (99.5%)
MTBE or EtOH for Gasoline
WTP Overall Efficiency: 80%
Petroleum Refining to Gasoline (84.5-86%,
Depending on Oxygenates and Reformulation)
Petroleum Refining to Gasoline (84.5-86%,
Depending on Oxygenates and Reformulation)
NG to MeOH Corn
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Key Issues for
Simulating Petroleum Fuels
Beginning in 2004, gasoline sulfur content will be
reduced nationwide from the current level of 150-
300 ppm to 30 ppm In addition, marginal crude has high sulfur content
Desulfurization in petroleum refineries adds stress
on refinery energy use and emissions
Ethanol could replace MTBE in RFG nationwide
Energy and emission differences in MTBE and ethanol
Differences in gasoline blend stocks for MTBE and
ethanol
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Ethanol WTP Pathways Include Activities
from Fertilizer to Ethanol at Stations
Agro-Chemical Production
Corn FarmingCorn Farming
Refueling Stations
Agro-Chemical Transport
Corn Transport
Transport, Storage, and
Distribution of Ethanol
Electricity
(Cell. Ethanol)
Woody Biomass FarmingWoody Biomass Farming Herbaceous Biomass FarmingHerbaceous Biomass Farming
Woody Biomass Transport Herbaceous Biomass Transport
Animal Feed
(Corn Ethanol)
Ethanol ProductionEthanol Production
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Recycling of Carbon by Ethanol
Fuel Results in Large CO2 Benefits for It
Ethanol plant
Carbon in
ethanol
Carbon in
corn kernels
Carbonin soil
Carbonin crop
residue
CO2 via photosynthesis
CO2 in theatmosphere
CO2 emissionsfrom ethanol
combustion
CO2emissionsduring
fermentation
K P t f Eth l’
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Key Parameters for Ethanol’sEnergy and Emission Effects
Energy use for chemicals
production
Fertilizers (N, P2O5, K2O)
Herbicides
Insecticides
Farming
Corn and biomass yield
Chemicals use intensity
Energy use intensity
Soil N2O and NOx emissions Soil CO2 emissions or
sequestration
Ethanol production
Corn ethanol: wet vs. dry
milling
Ethanol yield Energy use intensity
Co-product types and yields
Vehicle fuel economy Gasoline vehicles with E10
Flexible-fuel vehicles with E85
S C O f
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0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
1965 1970 1975 1980 1985 1990 1995 2000 2005
B u s h
e l s / l b .
F e r t i l i z e r
U.S. Corn Output Per Pound of Fertilizer
Used Has Risen (3-yr Moving Average)
Source: from USDA data.
Precision
farming, etc.?
?Some earlier studies
showed negative energy
balance for corn ethanol
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N2O and NOx Emissions from Nitrogen
Fertilizer Are a Major Emission Source
Some nitrogen fertilizer is converted into N2O
and NOX via nitrification and denitrification in
farmland
Depending on soil type and condition, 1-3% of
N in nitrogen fertilizer is converted into N in
N2O
On the well-to-wheels basis, N2O emissions
from nitrogen fertilizers could account for up to25% of total GHG emissions from corn ethanol
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Technology Has Reduced
Energy Use Intensity of Ethanol Plants
Source: from Argonne’s discussions with ethanol plant designers and recent USDA data.
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
B t u
/ G a l l o n
Wet Mill Dry Mill
1980s
2000s
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Well-to-Gate Energy andEmissions Allocated to Co-Products(Animal Feed) Vary by Allocation Method
Allocation Method Wet milling Dry milling
Weight 52% 51%
Energy content 43% 39%
Process energy 31% 34%
Market value 30% 24%
Displacement ~16% ~20%• Weight and energy methods no longer used
• Some studies did not consider co-products at all
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0.0
0.5
1.0
1.5
2.0
2.5
3.0
T o t a l
E n e r g y
F o s s i l
P e t r o l e u m
T o t a l
E n e r g y
F o s s i l
P e t r o l e u m
T o t a l
E n e r g y
F o s s i l
P e t r o l e u m
RFG Corn EtOH Cell. EtOH
B t u / b t u
Energy Benefits of Fuel Ethanol Lie
in Fossil Energy and Petroleum Use
Energy in fuel
Energy for
producing fuel
Uncertainty
Range
Energy Use for Each Btu of Fuel Used
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Energy in Different Fuels
Can Have Very Different Qualities
Fossil Energy Ratio (FER) =
energy in fuel/fossil energy input
1.4
0.980.8
0.42
0
1
2
3
4
Cell. EtOH Corn EtOH Coal Gasoline Electricity
F o s s i l E n e r g y R a t i o
18.5
Petroleum energy ratios for ethanol, coal,
and electricity are much greater than one.
I n c r e a s e i n E n e r g y Q u a l i t
y
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Changes in Energy Use Per Gallon
of Ethanol Used (Relative to Gasoline)
-120000
-80000
-40000
0
40000
80000
120000
T o t a l
E
n e r g y
F o s s i l
P e t r
o l e u m
T o t a l
E
n e r g y
F o s s i l
P e t r
o l e u m
T o t a l
E
n e r g y
F o s s i l
P e t r
o l e u m
T o t a l
E
n e r g y
F o s s i l
P e t r
o l e u m
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 GV: Corn EtOH E10 GV: Cell. EtOH
B t u
C h a n g e / E t O H G a l l o n
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Changes in Greenhouse Gas Emissions per
Gallon of Ethanol Used (Relative to Gasoline)
-10000
-8000
-6000
-4000
-2000
0 C O 2
G H G
C O 2
G H G
C O 2
G H G
C O 2
G H G
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 GV: Corn EtOH E10 GV: Cell. EtOH
G H
G
C h a n g e i n G
r a m s / E t O H G a
l l o
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Changes in Greenhouse Gas Emissions
per Mile Driven (Relative to GVs)
-90%
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
0%
C O 2
G H G
C O 2
G H G
C O 2
G H G
C O 2
G H G
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 GV: Corn EtOH E10 GV: Cell. EtOH
C h a n g e
s R e l a t i v e t o G V s
T t ti L i ti C Aff t
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Transportation Logistics Can Affect
Ethanol Emissions
Rail
Barge
Truck
Rail
Barge
Ocean
Tanker
Truck
Truck
Local
Collection
Long-Distance
TransportationLocal
Distribution
Ethanol
Plants
Bulk
Terminals
TerminalsRefueling
Stations
T t ti f Mid t Eth l t
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Transportation of Midwest Ethanol to
California is Accomplished via Rail and Ocean
Based on Pat Perez of CEC.
Midwest Supply - Majority of Supply to California
SF BayRefineries
Los Angeles
Refineries
Oregon
Terminals
Changes in Energy Use by Corn
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Changes in Energy Use by Corn
Ethanol: Midwest Use vs. California Use
-100000
-80000
-60000
-40000
-20000
0
20000
40000
T o t a l
E
n e r g y
F o s s i l
P e t r o l e u m
T o t a l
E
n e r g y
F o s s i l
P e t r o l e u m
T o t a l
E
n e r g y
F o s s i l
P e t r o l e u m
Corn EtOH in Midwest Corn EtOH in CA via Rail Corn EtOH in CA via Ocean
B t u C
h a n g e / E t O H G a
l l o n
Results are based ethanol in E85
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Changes in Greenhouse Gas Emissions by
Corn Ethanol: Midwest Use vs. California Use
-4000
-3000
-2000
-1000
0 C O 2
G H G
C O 2
G H G
C O 2
G H G
Corn EtOH in Midwest Corn EtOH in CA via Rail Corn EtOH in CA via Ocean
G H
G
C h a n g e i n G r
a m s / E t O H G a l l o
Results are based ethanol in E85
Energy Balance of Ethanol
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Energy Balance of Ethanol
Results Among Studies
-40,000
-30,000
-20,000
-10,000
0
10,000
20,000
30,000
40,000
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
N e t E n e r g y V a l u e ( B t u / g a l l o n )
Ho
Marland and Turhollow
Pimentel Pimentel
Keeney and DeLuca
Lorenz and Morris
Shapouri et al.
Shapouri et al.
Wang et al.
Agri. Canada
Kim and
DaleGraboski
Wang
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Ethanol GHG Emission Changes Among Studies
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
EPA
(1989):
E100
EPA
(1989):
E85
Ho
(1990):
E100
Marland
(1991):
E100
Delucchi
(1991):
E100
Ahmed
(1994):
E100
Delucchi
(1996):
E95
Wang
(1996):
E100
Wang
(1996):
E85
Wang
(1997):
E85
Agri.
Can.
(1999):
E85
Delucchi
(2001):
E90
Wang
(2003):
E85
G H G C h a n g e s
In long Run Cellulosic Ethanol Could
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In long Run, Cellulosic Ethanol Could
Play an Important Role in Energy Benefits
0 1,000 2,000 3,000 4,000 5,000 6,000
Renewable Electrolysis H2 FCV
Cellulosic EtOH FCV
NG Central H2 FCV
NG FTD HEV
Diesel HEV
Gasoline FCV
Gasoline HEV
Baseline GV
WTW Per-Mile Fossil Fuels Energy Use (Btu/mi.)
PTW
WTPOil
Natural Gas
Non-Fossil Domestic
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Cellulosic Ethanol Could Also Play
an Important Role in GHG Reductions
-300 -200 -100 0 100 200 300 400 500
Renewable Electrolysis H2 FCV
Cellulosic EtOH FCV
NG Central H2 FCV
NG FTD HEV
Diesel HEV
Gasoline FCV
Gasoline HEV
Baseline GV
WTW Per-Mile GHG Emissions (g/mi.)
PTW
WTP
Oil
Natural Gas
Non-Fossil Domestic
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Conclusions
Any type of fuel ethanol helps substantially reducetransportation’s fossil energy and petroleum use
Though studies now show that ethanol haspositive energy balance values, energy balance
values alone are not meaningful
Corn-based fuel ethanol achieves moderate
reductions in GHG emissions
Cellulosic ethanol will achieve much greater
energy and GHG benefits
Some WTW Analysis
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Some WTW Analysis
Issues Need to Be Noted
Multiple products System expansion vs. allocation (GREET takes both)
System expansion: allocation vs. attribution of effects
Technology advancement over time Current vs. emerging technologies – leveling comparison field
Static snap shot vs. dynamic simulations of evolving technologiesand market penetration over time
Dealing with uncertainties Risk assessment vs. sensitivity analysis
Regional differences, e.g, CA vs. the rest of the U.S.
Trade-offs of impacts WTW results are better for identifying problems than for
giving the answers