Argonne National Laboratory is managed by The University of Chicago for the U.S. Department of Energy
Energy and Greenhouse Gas Emissions Results of Fuel Ethanol
Michael WangCenter for Transportation ResearchArgonne National Laboratory
2
U.S. Fuel Ethanol Production Has Experienced Large Increases, and the Trend Will Continue
Source: Renewable Fuels Association
0
1000
2000
3000
4000
5000
6000
7000
8000
1980
1981
1982
1983
1984
1985
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1989
1990
1991
1992
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1996
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2012
Mill
ion
s o
f g
allo
ns
/Ye
ar
Actual ProductionEnergy Bill Requirement
3
Comparative Results Between Ethanol and Gasoline Are More Relevant to Policy Debate
4
Even Though Electricity Has a Large Negative Net Energy Balance, There Is No Substitute for Its Main Uses
Coal Mining
CoalTransportation
NGProcessing
NGTransmission
NGRecovery
Coal NG
Diesel FuelElectricity
NG
Diesel Fuel
NGElectricity
LPG, NGLs
NGElectricity
Electricity Generation
Electricity Transmissionand Distribution (8% loss)
1 mm Btu of Electricityat Wall Outlets
Uranium Ore Recovery
Petroleum Recovery
Uranium Petroleum
Uranium OreTransportation
PetroleumTransportation
OtherPetroleumProducts
Residual Oil
Electricity
Diesel Fuel
NG
Uranium Enrichment
Petroleum Refinery
Electricity
Refinery Gas
CoalNG
Uranium Fuel Transportation
Residual Oil TransportationDiesel Fuel
Residual Oil
ElectricityNG
Diesel FuelElectricity
NG
U.S. Electricity Generation:2.34 mm Btu Fossil Energy Input
for each 1.00 mm Btu Electricity Output
5
Energy in Different Fuels Can Have Very Different Qualities
Increase in Energy Quality
Fossil Energy Ratio (FER) = energy in fuel/fossil energy input
10.31
1.36
0.980.81
0.45
0.0
0.5
1.0
1.5
2.0
Cell. EtOH Corn EtOH Coal Gasoline Electricity
6
Accurate Ethanol Energy Analysis Must Account for Increased Productivity in Farming Over Time
Based on historical USDA data; results are 3-year moving averages
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
?
Precision farming, etc.?
U.S. Corn Output Per Pound of Fertilizer Has Risen by 70% in The Past 35 Years
7
Improved Technology Has Reduced Energy Use and Operating Costs in Corn Ethanol Plants
Source: from Argonne’s discussions with ethanol plant designers, recent USDA data, and other reported 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
8
One-Third of Corn Kernel Mass Ends as Animal Feed (a Co-Product) in Ethanol Plants
Protein
Dis
till
ers
Dry
G
rain
s an
d
So
lub
les
(DD
GS
)
EthanolStarch
Carbon Dioxide
Dairy: 46%
Beef: 39%
Poultry: 4%
Swine: 11%
2003 North American DDGS Consumption
Source: Commodity Specialist Co. (in RFA, 2005)
9
Accounting for Animal Feed Is a Critical Factor in Ethanol’s Lifecycle Analysis
Allocation Method Wet milling Dry milling Weight 52% 51%
Energy content 43% 39%
Process energy 36% 41%
Market value 30% 24%
Displacement ~16% ~20%
• Weight and energy methods are no longer used• Argonne uses the displacement method, the most conservative approach
• Some studies do not consider co-products at all
10
Cellulosic Ethanol Plants Will Be Significantly More Efficient than Corn Ethanol Plants
Steam
Biomass Feedstock Pretreatment Fermentation Separation
Power Plant: Gas and/or Steam Turbine Electricity Effluent
Discharge
Emissions
Fuel Ethanol
Wastewater
Emissions Emissions
Emissions
Solid Residue and Methane Wastewater
Treatment
Plants under intensive R&D efforts are designed to use the unfermentable portion of biomass to generate steam and electricity.
11
0.0
0.5
1.0
1.5
2.0
2.5
RFG CornEtOH:
DM
CornEtOH:
WM
Cell.EtOH
RFG CornEtOH:
DM
CornEtOH:
WM
Cell.EtOH
RFG CornEtOH:
DM
CornEtOH:
WM
Cell.EtOH
Btu for Fuel Production
Btu in Fuel
Energy Effects of Fuel Ethanol Depend on the Type of Energy Being Analyzed
Total Btu Spent for One Btu of Gasoline and Ethanol Available at Fuel Pumps
Total Energy
Fossil Energy
Petroleum Energy
12
Use of Ethanol to Replace Gasoline Results in Fossil Energy and Petroleum Reduction Benefits
2.1% 4.7%
24.3%
52.3%
-3.2% -6.5%
-32.9%
-69.1%
-6.3% -6.3%
-69.5% -70.0%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
E10 GV:CornEtOH
E10 GV:Cell.EtOH
E85FFV:CornEtOH
E85FFV:Cell.EtOH
E10 GV:CornEtOH
E10 GV:Cell.EtOH
E85FFV:CornEtOH
E85FFV:Cell.EtOH
E10 GV:CornEtOH
E10 GV:Cell.EtOH
E85FFV:CornEtOH
E85FFV:Cell.EtOH
Total Energy
Fossil Energy Petroleum Energy
Change in Per-Mile Energy Use by Ethanol Blend to Displace Gasoline
13
Ethanol Blends, Especially E85 Made from Cellulosic Ethanol, Can Significantly Reduce GHG Emissions
Reductions in Per-Mile GHG Emissions by Ethanol Blend to Displace Gasoline
-2% -2%-6%
-23%
-17%
-64%
-80%
-60%
-40%
-20%
0%
E10 GV: DMCorn EtOH
E10 GV: WMCorn EtOH
E10 GV: Cell.EtOH
E85 FFV: DMCorn EtOH
E85 FFV: WMCorn EtOH
E85 FFV:Cell. EtOH
14
Corn EtOH Reduces GHGs by 18-29% While Cellulosic EtOH Yields 85-86% Reduction, on Per Gallon Basis of EtOH Used
GHG Emission Reductions Per Gallon of Ethanol to Displace An Energy-Equivalent Amount of Gasoline
-26%
-18%
-85%
-29%
-21%
-86%
-100%
-80%
-60%
-40%
-20%
0%
E10 GV: DMCorn EtOH
E10 GV: WMCorn EtOH
E10 GV: Cell.EtOH
E85 FFV: DMCorn EtOH
E85 FFV: WMCorn EtOH
E85 FFV: Cell.EtOH
15
Most of the Recent Corn EtOH Studies Show a Positive Net Energy Balance
-120,000
-100,000
-80,000
-60,000
-40,000
-20,000
0
20,000
40,000
60,000
1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Net
En
erg
y V
alu
e (B
tu/g
allo
n)
Ho
Marland&Turhollow
Pim ente l
Pim ente lKeeney&DeLuca
Lorenz&Morris
Shapouri e t al.
Wang et al.
Agri. Canada
Kim &DaleGraboski
Wang
Pim ente l
Shapouri e t al.
Pim ente l&Patzek
Weinblatt e t al.
NR Canada
Cham bers et al.
Patzek
DelucchiKim &Dale
Wan
g
GR
EE
T
w/P
imen
tel
Ass
um
pti
on
s
Energy balance here is defined as Btu content a gallon of ethanol minus fossil energy used to produce a gallon of ethanol
16
Energy Balance Results of Ethanol Depend Heavily on System Boundary Choices
Operation-Related Activities:Fertilizer, Farming,
Corn Transportation, 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
17
The Debate on Energy Balance Itself May Have Little Practical Meaning
Though self evaluation of a fuel’s energy balance is easy to understand, to do so for a fuel in isolation could be arbitrary
All Btus are not created equal. The energy sector has been converting low-value Btus into high-value Btus, with energy losses
Society has not made energy choice decisions on the basis of energy balance values of individual energy products
Issues of concern, such as petroleum consumption and GHG emissions, should be analyzed directly for fuel alternatives
A complete, robust way of evaluating a fuel’s effects is to compare the fuel (e.g., ethanol) with those to be displaced (e.g., gasoline)
18
Most Studies on GHG Emissions Show GHG Emission Reduction by Corn EtOH as Compared to Gasoline
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
GH
G C
han
ges
19
A Recent Article by UC Berkeley Questioned the Analyses by Piemntel and Patzek (Science, Jan. 27, 2006)
Examined six representative analyses Used GREET for many parameters in authors’ own calculations Included the following additional items:
Energy and emissions embedded in farming equipments and ethanol plants for corn ethanol; energy and emissions embedded in oil field equipment and petroleum refineries seem not to be included; but the contributions are small
Energy and emissions of water use and water treatment in ethanol plants; potential double-counting with ethanol plant energy use already considered?
Lime application: 988 lbs/acre/yr vs. 16 lbs/acre/yr by USDA; the single most important factor determining difference between UC Berkeley and ANL
The study concluded GHG emission reductions by corn ethanol of 13% for today’s technology Significant petroleum reductions by corn ethanol Much greater energy and GHG benefits by cellulosic ethanol Studies by Pimentel and Patzek incorrectly ignored coproducts and used some
obsolete data
20
Looking into Future: Opportunities and Risks of Corn Ethanol Energy and Emission Effects
Factors with positive effects Corn yield per acre will continue to increase, together with stabilized or
reduced N fertilizer application Ethanol yield per bushel will continue to increase Energy use in ethanol plants may be reduced further through better
engineering, integration of ethanol production and animal feedlots Gasification of biomass to provide process energy for ethanol plants
Factors with negative effects Switch from natural gas to coal for process energy in ethanol plants Use of marginal land for additional corn production
Has the debate of food vs. fuel been dead? Potential use of DGS as a process fuel could renew this debate
21
Conclusions
Energy balance value for a given energy product alone is not meaningful in evaluating its benefit
Any type of fuel ethanol helps substantially reduce fossil energy and petroleum use, relative to petroleum gasoline
Corn-based fuel ethanol achieves moderate reductions in GHG emissions
Cellulosic ethanol can achieve much greater energy and GHG benefits
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