fuel-cycle energy and greenhouse gas emission impacts of fuel ethanol michael wang center for...
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Fuel-Cycle Energy and Greenhouse Gas Emission Impacts of Fuel Ethanol
Michael WangCenter for Transportation Research
Argonne National Laboratory
Workshop on Economic and Environmental
Impacts of Bio-Based Production Chicago, IL, June 8-9, 2004
U.S. Now Consumes about 19 Million B/D of Oil, Transportation Accounts for ~75%
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3
6
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15
18
21
24
27
30
1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025
Pe
tro
leu
m U
se
(M
MB
DO
E)
Water
Rail
Actual Projection
Automobiles
Air
Light Trucks
Heavy Veh
U.S. ProductionOff-Road
Other Uses
Data sources: ORNL (2003), the Transportation Energy Databook; EIA (2003), Annual Energy Outlook; Annual Energy Review
North America Has Relatively Little Conventional Oil But 30% of Unconventional Oil Reserves
0
200
400
600
800
1000
1200
Middle East North America Other Total
Bill
ion
Barr
els
Cru
de E
qv
Conventional Oil
Unconventional Oil
The Transportation Sector is the Second Largest U.S. GHG Emitting Source
EPA (2003), Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2001
0
500
1,000
1,500
2,000
2,500
1990
1991
1992
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1995
1996
1997
1998
1999
2000
Mil
lio
n M
etr
ic T
on
s o
f C
O2
Eq
.
Electricity Generation TransportationIndustry AgricultureResidential Commercial
U.S. Has Had and Will Continue to Have the Highest Total GHG Emissions
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
U.S
.
Ch
ina
Ind
ia
Ja
pa
n
Ge
rma
ny
Ca
na
da
S.
Ko
rea
U.K
.
Ita
ly
Fra
nc
e
CO
2-E
qu
iv.
GH
Gs (
Mil
lio
n M
T)
2001
2025
GAO (2003), Greenhouse Gas Emission Intensity
Reductions of Oil Use and GHG Emissions Could Be Major Goals for the U.S. Transportation Sector
Many ways have been studied and have potentials to reduce transportation oil use and GHG emissions
Advanced vehicle technologies Hybrid electric vehicles Fuel cell vehicles
New transportation fuels Biofuels such as cellulosic ethanol Non-petroleum fuels Hydrogen produced from different energy sources,
especially from renewable sources
Cycles for Vehicle/Fuel SystemsThe Illustration is for Petroleum-Based
Fuels
Vehicle Cycle
Fuel Cycle
Well to Pump
Pu
mp
to W
heels
WTP: well-to-pumpPTW: pump-to-wheelsWTW: well-to-wheels (WTP + PTW)
WTW Analysis Is a Complete Energy/Emissions Comparison
As an example, greenhouse gases are illustrated here
The GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) 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 1,200 registered GREET users
Biofuel Pathways and Fueled Vehicle Technology Options Currently in GREET
Feedstock
Fuel Prod.Technology
Fuel
Vehicle Technology
Corn
Fermentation
Ethanol
Farmed Woody and Herbaceous Biomass
Oxygenated RFG: GVsLow-level blend (~E10): GVsHigh-level blend (~E85): FFVs and hybridsE100: FCVs (on-board reforming)
Soybeans
Transesterification
Biodiesel
Blend of BD10-BD50: CI engines CI hybrids
Additional Bio-fuel Production Pathways Are Being Added to GREET
Biomass gasification to produceEthanolMethanolFT dieselDimethyl etherHydrogen
Hydrogen production from reforming of ethanol and methanol at refueling stations
U.S. Fuel Ethanol Use Has Increased Steadily
Source: Renewable Fuels Association’s 2004 Ethanol Industry Outlook Report.
0
500
1,000
1,500
2,000
2,500
3,000
Mill
ion
Ga
llon
s/Y
ea
r
19
80
19
81
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84
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86
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00
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02
20
03 In 2003, the U.S. used 2.8
billion gallons of fuel ethanol
Type Purpose Mil. Gal.FRFG Oxygenate (E6-E10) 1,350 F.Winter Oxy. Fuels Oxygenate (E10) 250 MN Oxy. Fuels Oxygenate (E10) 260 Conv. Gasoline Octane/Extender 950 Total 2,810
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 true energy 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
Ethanol 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
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
Bu
shel
s/lb
. Fer
tiliz
er
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
For Corn EtOH, N2O Emissions from Nitrogen Fertilizer Are a Key GHG 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 to 25% of total GHG emissions from corn ethanol
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
Btu
/Ga
llon
Wet Mill Dry Mill
1980s
2000s
Well-to-Gate Energy and Emissions 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
System Boundary Affects Results of Ethanol Greatly
Operation-Related Activities:Fertilizer, Farming, Farming
Transportation Activities, EthanolProduction, Ethanol Transportation,
Energy Use for Producing Process Fuels
Farming Equipment Materials
and Manufacture
Ethanol Plant Materials
and Construction
Food Intake by Farmers
Solar Energy Embedded
in Biomass
0.0
0.5
1.0
1.5
2.0
2.5
3.0T
ota
lE
ner
gy
Fo
ssil
Pet
role
um
To
tal
En
erg
y
Fo
ssil
Pet
role
um
To
tal
En
erg
y
Fo
ssil
Pet
role
um
RFG Corn EtOH Cell. EtOH
Btu
/btu
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
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
Fo
ssil
En
erg
y R
atio
18.5
But, petroleum energy ratios for ethanol, coal, and electricity are much greater than one!!
Increase in Energy
Quality
Petroleum Refining Is the Key Energy Conversion Step for Gasoline
Petroleum Recovery (97%)
Gasoline at Refueling Stations
Petroleum Transportand 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
Key Issues for Simulating Petroleum Fuels
Beginning in 2004, gasoline sulfur content is reduced nationwide from the previous level of 150-300 ppm to 30 ppm
In addition, marginal crude has high sulfur content
New crude supply such as Canadian oil sands is energy intensive to recover and process
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
Changes in Energy Use Per Gallon
of Ethanol Used (Relative to Gasoline)
-120,000
-80,000
-40,000
0
40,000
80,000
120,000To
tal
Ene
rgy
Foss
il
Pet
role
um
Tota
lE
nerg
y
Foss
il
Pet
role
um
Tota
lE
nerg
y
Foss
il
Pet
role
um
Tota
lE
nerg
y
Foss
il
Pet
role
um
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 FFV; Corn EtOH E10 FFV: Cell. EtOH
Btu
Cha
nge/
EtO
H G
allo
n
Changes in Greenhouse Gas Emissions per Gallon of Ethanol Used (Relative to Gasoline)
-10000
-8000
-6000
-4000
-2000
0
CO
2
GH
G
CO
2
GH
G
CO
2
GH
G
CO
2
GH
G
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 FFV: Corn EtOH E10 FFV: Cell. EtOH
GH
G C
hang
e in
Gra
ms/
EtO
H G
allo
n
Changes in Greenhouse Gas Emissions per Mile Driven (Relative to GVs)
-90%
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
0%C
O2
GH
G
CO
2
GH
G
CO
2
GH
G
CO
2
GH
G
E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 GV: Corn EtOH E10 GV: Cell. EtOH
Ch
ang
es R
elat
ive
to G
Vs
Transportation Logistics Could Affect Ethanol Energy and Emissions
Rail
Barge
Truck
Rail
Barge
Ocean Tanker
Truck
Truck
Local Collection
Long-Distance Transportation
Local Distribution
Ethanol Plants
Bulk Terminals
TerminalsRefueling Stations
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 Bay Refineries
Los Angeles Refineries
Oregon Terminals
Changes in Greenhouse Gas Emissions by Corn Ethanol: Midwest Use vs. California Use
-4000
-3000
-2000
-1000
0
CO
2
GH
G
CO
2
GH
G
CO
2
GH
G
Corn EtOH in Midwest Corn EtOH in CA via Rail Corn EtOH in CA via Ocean
GH
G C
han
ge
in G
ram
s/E
tOH
Gal
lon
Results are based ethanol in E85
An Argonne Study Shows That Corn Ethanol in Diesel May Not Have GHG Benefits
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
CO
2
GH
G
CO
2
GH
G
CO
2
GH
G
LSD Bus ED10 BUS ED15 BUS
Gra
ms/
Mile
Energy Balance of Corn 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
Net
En
erg
y V
alu
e (
Btu
/gallo
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 Dale
Graboski
Wang
Corn 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
GH
G C
ha
ng
es
Vehicle Fuel Economy Is One of the Most Important Factors for WTW Results
Fuel economy ratios are relative to improved future gasoline ICE technology;On-road 55/45 MPG of baseline GV is assumed to be 27.5, a 22% improvement from 2000 MY midsize car MPG
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
CNGV LPGV E85 FFV GasolineHybrid
DieselHybrid
GasolineandEtOHFCV
MeOHFCV
GH2 FCV BP EV
Fu
el E
co
no
my
Ra
tio
MIT 2003 GM 2001 MIT 2000
A GM/ANL Study Takes the Following Key Assumptions for PTW Emissions
Propulsion System Assumed Emission Performance Gasoline and E85 ICE Tier 2 Bin 5 Diesel and CNG ICE Tier 2 Bin 5, but no evap VOC Hydrogen ICE Tier 2 Bin 2, no evap, Bin 5 NOx Fuel processor fuel cell Tier 2 Bin 2 Hydrogen fuel cell Tier 2 Bin 1 (zero emissions)
2010 MY Vehicle Emissions Targets
Fuel consumption penalties of aftertreatment systems to meet standards were considered in the study
Bin 5 diesel has not been demonstrated MY 2010 vehicle in-use emissions in 2016 were modeled using
• EPA MOBILE 6.2
• ARB EMFAC2002 version 3
Vehicle/Fuel Technologies for WTW Energy and GHG Emission Results
Crude oil-based technologiesRFG ICE LPG ICE
LS Diesel ICE RFG ICE hybrid
Gasoline FCV LS diesel ICE hybrid
Natural gas-based technologiesFT diesel ICE CNG ICE
FT diesel ICE hybrid MeOH FCV
G.H2 FCV
Bioethanol and ElectricityCorn E85 ICE FFV Cellulosic EtOH FCV
U.S. average electri.-to-G.H2 FCV Renewable electricity-to-G.H2 FCV
U.S. average electricity battery-powered EV
Vehicle/Fuel Technologies for WTW Criteria Pollutant Emission Results
Crude oil-based technologiesRFG displacement on demand (DOD) SI conventional drive (CD)
RFG DI SI CD LS Diesel DI CI CD
RFG DOD SI hybrid LS diesel DI CI hybrid
Gasoline fuel-processor (FP) FCV
Natural gas-based technologiesCNG DOD SI CD FT diesel DI CI CD
G.H2 SI CD MeOH FP FCV
G.H2 FCV L.H2 FCV
Bioethanol and ElectricityCorn E85 DOD SI CD Cellulosic E85 DOD SI CD
Cellulosic EtOH FP FCV U.S. average electri.-to-G.H2 FCV
NG CC electri.-to-G.H2 FCV Renewable electricity-to-G.H2 FCV
37
WTW Total Energy Use of Selected Vehicle/Fuel Systems
0
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9,000
Btu
/Mile
Crude oil feedstock
Natural gas feedstock
Electricity and EtOH
WTW Fossil Energy Use of Selected Vehicle/Fuel Systems
0
1,000
2,000
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4,000
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6,000
7,000
Btu
/Mile
Crude oil feedstock
Natural gas feedstock
Electricity and EtOH
WTW GHG Emissions of Selected Vehicle/Fuel Systems
0
100
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300
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500
600
Gra
ms
/Mile
Crude oil feedstock Natural gas
feedstock
Electricity and EtOH
WTW Urban NOx Emissions of Selected Vehicle/Fuel Systems
0.00
0.05
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0.15
0.20
0.25
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0.35
WT
W U
rban
NO
x E
mis
sio
ns, g
/mile Well to Pump Pump to Wheels
Oil-BasedNG-Based
Bioethanol and Electricity
WTW Urban PM10 Emissions of Selected Vehicle/Fuel Systems
0.00
0.01
0.02
0.03
0.04
0.05
WT
W U
rban
PM
10 E
mis
sio
ns, g
/mile Well to Pump Pump to Wheels
Oil-BasedNG-Based
Bioethanol and Electricity
Conclusions Either corn or cellulosic ethanol helps
substantially reduce transportation’s fossil energy and petroleum use
Ethanol’s energy balance alone has limited public policy information content
Corn-based fuel ethanol achieves moderate reductions in GHG emissions
Cellulosic ethanol will achieve much greater energy and GHG benefits
Outstanding Issues in WTW Analyses Need to Be Addressed Continuously
Multiple products System expansion vs. allocation (GREET takes both) System expansion: allocation vs. attribution of effects
Technology advancement over time Current vs. future technologies – leveling comparison field Static snap shot vs. dynamic simulations of evolving
technologies and market penetration over time (a new GREET version conducts simulations over time)
Dealing with uncertainties Stochastic analysis vs. conventional sensitivity analysis Regional differences, e.g, CA vs. the rest of the U.S.
Trade-offs of impacts: value-driven?
WTW results may be better for identifying problems than for providing the answers