Fuel-Cyclel Energy and Greenhouse Gas Emission ... - GREET Model
Fuel-Cycle Energy and Greenhouse Emission Impacts of Fuel Ethanol Michael Wang Center for Transportation Research Argonne National Laboratory Presentation at EPA Cincinnati Cincinnati, Ohio, May 8, 2003
Cycles for Vehicle/Fuel Systems The Illustration is for Petroleum-Based Fuels
Vehicle Cycle WTP: well-to-pump PTW: pump-to-wheels WTW: well-to-wheels (WTP + PTW)
Well to Pump
Pump to Wheels
Fuel Cycle
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 about 800 registered GREET users
U.S. Fuel Ethanol Production and Use Have Increased Steadily
In 2002, the U.S. used 2.1 billion gallons of fuel ethanol
Source: Renewable Fuels Association’s 2003 Ethanol Industry Outlook Report.
Type FRFG F.Winter Oxy. Fuels MN Oxy. Fuels Conv. Gasoline Total
Purpose Oxygenate (E6-E10) Oxygenate (E10) Oxygenate (E10) Octane/Extender
Mil. Gal. 700 250 250 900 2,100
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
Emission Effects of Fuel Ethanol Were Not Addressed on the Fuel-Cycle Basis Past emission studies focused mainly on ethanol’s evaporative emissions and its effects on vehicle tailpipe emissions Well-to-pump emissions were identified for ethanol and gasoline 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 a holistic and comparative way For criteria pollutant emissions, future emission controls for WTP and vehicle activities are important
GREET Calculation Logic for Production Activities Inputs Emission Factors
Combustion Tech. Shares
Calculations
Energy Efficiencies
Fuel Type Shares
Facility Location Shares
Energy Use by Fuel Type
Total Emissions
Urban Emissions
GREET Calculation Logic for Transportation Activities Energy EnergyIntensity Intensity (Btu/ton-mile) (Btu/ton-mile)
Share of Process Fuels
Transport Transport Distance Distance(mi.) (mi.)
Emission EmissionFactors Factors (g/mmBtu (g/mmBtufuel fuelburned) burned)
Energy Use by Mode (Btu/mmBtu Fuel Transported)
Emissions by Mode (g/mmBtu Fuel Transported)
Mode ModeShare Share
Energy Consumption (Btu/mmBtu Fuel Transported)
Emissions (g/mmBtu Fuel Transported)
GREET Is Designed to Conduct Stochastic Simulations Distribution-Based Inputs Generate Distribution-Based Outputs
Petroleum Refining Is the Key Energy Conversion Step for Gasoline Petroleum Recovery (97%) Petroleum Transport and Storage (99%)
NG to MeOH
Corn
MTBE or EtOH for Gasoline
Petroleum PetroleumRefining Refiningto toGasoline Gasoline(84.5-86%, (84.5-86%, Depending Dependingon onOxygenates Oxygenatesand andReformulation) Reformulation) Transport, Storage, and Distribution of Gasoline (99.5%) WTP Overall Efficiency: 80%
Gasoline at Refueling Stations
Key Issues for Simulating Petroleum Fuels Beginning in 2004, gasoline sulfur content will be reduced nationwide from the current level of 150300 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
Ethanol WTP Pathways Include Activities from Fertilizer to Ethanol at Stations Agro-Chemical Production Agro-Chemical Transport Corn CornFarming Farming Woody WoodyBiomass BiomassFarming Farming Herbaceous HerbaceousBiomass BiomassFarming Farming Corn Transport Animal Feed (Corn Ethanol)
Woody Biomass Transport Herbaceous Biomass Transport Ethanol EthanolProduction Production Transport, Storage, and Distribution of Ethanol Refueling Stations
Electricity (Cell. Ethanol)
Recycling of Carbon by Ethanol Fuel Results in Large CO2 Benefits for It CO2 via photosynthesis
CO2 in the atmosphere
CO2 emissions during fermentation Carbon in corn kernels
Carbon in ethanol
Carbon in crop residue Carbon in soil
Ethanol plant
CO2 emissions from ethanol combustion
Key Parameters for Ethanol’s Energy and Emission Effects Energy use for chemicals Ethanol production Corn ethanol: wet vs. dry 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
milling Ethanol yield Energy use intensity Co-product types and yields
Vehicle fuel economy Gasoline vehicles with E10 Flexible-fuel vehicles with E85
U.S. Corn Output Per Pound of Fertilizer Used Has Risen (3-yr Moving Average) 0.65
Bushels/lb. Fertilizer
0.60
?
Some earlier studies showed negative energy balance for corn ethanol
0.55
Precision farming, etc.?
0.50 0.45 0.40 0.35 0.30 1965
1970
Source: from USDA data.
1975
1980
1985
1990
1995
2000
2005
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 to 25% of total GHG emissions from corn ethanol
Technology Has Reduced Energy Use Intensity of Ethanol Plants 70,000
1980s
60,000
2000s
Btu/Gallon
50,000 40,000 30,000 20,000 10,000 0
Wet Mill
Dry Mill
Source: from Argonne’s discussions with ethanol plant designers and recent USDA data.
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
Energy Benefits of Fuel Ethanol Lie in Fossil Energy and Petroleum Use 3.0
Btu/btu
2.5
Uncertainty Range
Energy for producing fuel
2.0 1.5 1.0 0.5
Energy in fuel
RFG
Corn EtOH
Cell. EtOH
Energy Use for Each Btu of Fuel Used
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
0.0
Energy in Different Fuels Can Have Very Different Qualities Fossil Energy Ratio (FER) = energy in fuel/fossil energy input 4
In cr
18.5
Fossil Energy Ratio
3
2
1.4 0.98
1
0.8 0.42
0 Cell. EtOH
Corn EtOH
Coal
Gasoline
Petroleum energy ratios for ethanol, coal, and electricity are much greater than one.
Electricity
ea se
in
En er
gy
Q
ua lit y
Changes in Energy Use Per Gallon of Ethanol Used (Relative to Gasoline) 80000 40000 0 -40000 -80000
E85 FFV: Corn EtOH
E85 FFV: Cell. EtOH
E10 GV: Corn EtOH
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
-120000 Total Energy
Btu Change/EtOH Gallon
120000
E10 GV: Cell. EtOH
Changes in Greenhouse Gas Emissions per Gallon of Ethanol Used (Relative to Gasoline)
GHG Change in Grams/EtOH Gallon
0
-2000
-4000
-6000
-8000
-10000
GHG
E10 GV: Cell. EtOH CO2
GHG
E10 GV: Corn EtOH CO2
GHG
E85 FFV: Cell. EtOH CO2
GHG
CO2
E85 FFV: Corn EtOH
Changes in Greenhouse Gas Emissions per Mile Driven (Relative to GVs) 0%
-20% -30% -40% -50% -60% -70% -80%
E85 FFV: Corn EtOH
E85 FFV: Cell. EtOH
E10 GV: Corn EtOH
GHG
CO2
GHG
CO2
GHG
CO2
GHG
-90% CO2
Changes Relative to GVs
-10%
E10 GV: Cell. EtOH
Transportation Logistics Can Affect Ethanol Emissions Local Collection
Long-Distance Transportation Rail
Rail Ethanol Plants
Barge Truck
Local Distribution
Bulk Terminals
Barge Ocean Tanker
Truck
Terminals
Truck
Refueling Stations
Transportation of Midwest Ethanol to California is Accomplished via Rail and Ocean
Oregon Terminals
SF Bay Refineries Los Angeles Refineries
Based on Pat Perez of CEC.
Midwest Supply - Majority of Supply to California
Changes in Energy Use by Corn Ethanol: Midwest Use vs. California Use 40000
0 -20000 -40000 -60000 -80000
Corn EtOH in Midwest
Results are based ethanol in E85
Corn EtOH in CA via Rail
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
-100000 Total Energy
Btu Change/EtOH Gallon
20000
Corn EtOH in CA via Ocean
Changes in Greenhouse Gas Emissions by Corn Ethanol: Midwest Use vs. California Use
GHG Change in Grams/EtOH Gallon
0
-1000
-2000
-3000
-4000
Results are based ethanol in E85
GHG
Corn EtOH in CA via Ocean
CO2
GHG
Corn EtOH in CA via Rail
CO2
GHG
CO2
Corn EtOH in Midwest
Energy Balance of Ethanol Results Among Studies 40,000 30,000
Lorenz and Morris
Net Energy Value (Btu/gallon)
20,000
Agri. Canada Wang et al.
Marland and Turhollow 10,000
Shapouri et al.
Shapouri et al. Kim and Wang Dale Graboski
0 -10,000
Ho Keeney and DeLuca
-20,000 -30,000 Pimentel Pimentel -40,000 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Ethanol GHG Emission Changes Among Studies 100% 80%
GHG Changes
60% 40% 20% 0% -20% -40% -60% -80% EPA (1989): E100
EPA (1989): E85
Ho Marland Delucchi Ahmed Delucchi Wang (1990): (1991): (1991): (1994): (1996): (1996): E100 E100 E100 E100 E95 E100
Wang (1996): E85
Wang (1997): E85
Agri. Delucchi Wang Can. (2001): (2003): (1999): E90 E85 E85
In long Run, Cellulosic Ethanol Could Play an Important Role in Energy Benefits PTW WTP
Baseline GV Gasoline HEV
Oil
Gasoline FCV Diesel HEV NG FTD HEV Natural Gas
NG Central H2 FCV Cellulosic EtOH FCV
Non-Fossil Domestic
Renewable Electrolysis H2 FCV 0
1,000
2,000
3,000
4,000
5,000
WTW Per-Mile Fossil Fuels Energy Use (Btu/mi.)
6,000
Cellulosic Ethanol Could Also Play an Important Role in GHG Reductions PTW WTP
Baseline GV Gasoline HEV Oil
Gasoline FCV Diesel HEV NG FTD HEV
Natural Gas
NG Central H2 FCV Cellulosic EtOH FCV
Non-Fossil Domestic
Renewable Electrolysis H2 FCV -300
-200
-100
0
100
200
300
WTW Per-Mile GHG Emissions (g/mi.)
400
500
Conclusions Any type of fuel ethanol helps substantially reduce transportation’s fossil energy and petroleum use Though studies now show that ethanol has positive 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 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 technologies and 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
Cycles for Vehicle/Fuel Systems The Illustration is for Petroleum-Based Fuels
Vehicle Cycle WTP: well-to-pump PTW: pump-to-wheels WTW: well-to-wheels (WTP + PTW)
Well to Pump
Pump to Wheels
Fuel Cycle
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 about 800 registered GREET users
U.S. Fuel Ethanol Production and Use Have Increased Steadily
In 2002, the U.S. used 2.1 billion gallons of fuel ethanol
Source: Renewable Fuels Association’s 2003 Ethanol Industry Outlook Report.
Type FRFG F.Winter Oxy. Fuels MN Oxy. Fuels Conv. Gasoline Total
Purpose Oxygenate (E6-E10) Oxygenate (E10) Oxygenate (E10) Octane/Extender
Mil. Gal. 700 250 250 900 2,100
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
Emission Effects of Fuel Ethanol Were Not Addressed on the Fuel-Cycle Basis Past emission studies focused mainly on ethanol’s evaporative emissions and its effects on vehicle tailpipe emissions Well-to-pump emissions were identified for ethanol and gasoline 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 a holistic and comparative way For criteria pollutant emissions, future emission controls for WTP and vehicle activities are important
GREET Calculation Logic for Production Activities Inputs Emission Factors
Combustion Tech. Shares
Calculations
Energy Efficiencies
Fuel Type Shares
Facility Location Shares
Energy Use by Fuel Type
Total Emissions
Urban Emissions
GREET Calculation Logic for Transportation Activities Energy EnergyIntensity Intensity (Btu/ton-mile) (Btu/ton-mile)
Share of Process Fuels
Transport Transport Distance Distance(mi.) (mi.)
Emission EmissionFactors Factors (g/mmBtu (g/mmBtufuel fuelburned) burned)
Energy Use by Mode (Btu/mmBtu Fuel Transported)
Emissions by Mode (g/mmBtu Fuel Transported)
Mode ModeShare Share
Energy Consumption (Btu/mmBtu Fuel Transported)
Emissions (g/mmBtu Fuel Transported)
GREET Is Designed to Conduct Stochastic Simulations Distribution-Based Inputs Generate Distribution-Based Outputs
Petroleum Refining Is the Key Energy Conversion Step for Gasoline Petroleum Recovery (97%) Petroleum Transport and Storage (99%)
NG to MeOH
Corn
MTBE or EtOH for Gasoline
Petroleum PetroleumRefining Refiningto toGasoline Gasoline(84.5-86%, (84.5-86%, Depending Dependingon onOxygenates Oxygenatesand andReformulation) Reformulation) Transport, Storage, and Distribution of Gasoline (99.5%) WTP Overall Efficiency: 80%
Gasoline at Refueling Stations
Key Issues for Simulating Petroleum Fuels Beginning in 2004, gasoline sulfur content will be reduced nationwide from the current level of 150300 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
Ethanol WTP Pathways Include Activities from Fertilizer to Ethanol at Stations Agro-Chemical Production Agro-Chemical Transport Corn CornFarming Farming Woody WoodyBiomass BiomassFarming Farming Herbaceous HerbaceousBiomass BiomassFarming Farming Corn Transport Animal Feed (Corn Ethanol)
Woody Biomass Transport Herbaceous Biomass Transport Ethanol EthanolProduction Production Transport, Storage, and Distribution of Ethanol Refueling Stations
Electricity (Cell. Ethanol)
Recycling of Carbon by Ethanol Fuel Results in Large CO2 Benefits for It CO2 via photosynthesis
CO2 in the atmosphere
CO2 emissions during fermentation Carbon in corn kernels
Carbon in ethanol
Carbon in crop residue Carbon in soil
Ethanol plant
CO2 emissions from ethanol combustion
Key Parameters for Ethanol’s Energy and Emission Effects Energy use for chemicals Ethanol production Corn ethanol: wet vs. dry 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
milling Ethanol yield Energy use intensity Co-product types and yields
Vehicle fuel economy Gasoline vehicles with E10 Flexible-fuel vehicles with E85
U.S. Corn Output Per Pound of Fertilizer Used Has Risen (3-yr Moving Average) 0.65
Bushels/lb. Fertilizer
0.60
?
Some earlier studies showed negative energy balance for corn ethanol
0.55
Precision farming, etc.?
0.50 0.45 0.40 0.35 0.30 1965
1970
Source: from USDA data.
1975
1980
1985
1990
1995
2000
2005
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 to 25% of total GHG emissions from corn ethanol
Technology Has Reduced Energy Use Intensity of Ethanol Plants 70,000
1980s
60,000
2000s
Btu/Gallon
50,000 40,000 30,000 20,000 10,000 0
Wet Mill
Dry Mill
Source: from Argonne’s discussions with ethanol plant designers and recent USDA data.
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
Energy Benefits of Fuel Ethanol Lie in Fossil Energy and Petroleum Use 3.0
Btu/btu
2.5
Uncertainty Range
Energy for producing fuel
2.0 1.5 1.0 0.5
Energy in fuel
RFG
Corn EtOH
Cell. EtOH
Energy Use for Each Btu of Fuel Used
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
0.0
Energy in Different Fuels Can Have Very Different Qualities Fossil Energy Ratio (FER) = energy in fuel/fossil energy input 4
In cr
18.5
Fossil Energy Ratio
3
2
1.4 0.98
1
0.8 0.42
0 Cell. EtOH
Corn EtOH
Coal
Gasoline
Petroleum energy ratios for ethanol, coal, and electricity are much greater than one.
Electricity
ea se
in
En er
gy
Q
ua lit y
Changes in Energy Use Per Gallon of Ethanol Used (Relative to Gasoline) 80000 40000 0 -40000 -80000
E85 FFV: Corn EtOH
E85 FFV: Cell. EtOH
E10 GV: Corn EtOH
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
-120000 Total Energy
Btu Change/EtOH Gallon
120000
E10 GV: Cell. EtOH
Changes in Greenhouse Gas Emissions per Gallon of Ethanol Used (Relative to Gasoline)
GHG Change in Grams/EtOH Gallon
0
-2000
-4000
-6000
-8000
-10000
GHG
E10 GV: Cell. EtOH CO2
GHG
E10 GV: Corn EtOH CO2
GHG
E85 FFV: Cell. EtOH CO2
GHG
CO2
E85 FFV: Corn EtOH
Changes in Greenhouse Gas Emissions per Mile Driven (Relative to GVs) 0%
-20% -30% -40% -50% -60% -70% -80%
E85 FFV: Corn EtOH
E85 FFV: Cell. EtOH
E10 GV: Corn EtOH
GHG
CO2
GHG
CO2
GHG
CO2
GHG
-90% CO2
Changes Relative to GVs
-10%
E10 GV: Cell. EtOH
Transportation Logistics Can Affect Ethanol Emissions Local Collection
Long-Distance Transportation Rail
Rail Ethanol Plants
Barge Truck
Local Distribution
Bulk Terminals
Barge Ocean Tanker
Truck
Terminals
Truck
Refueling Stations
Transportation of Midwest Ethanol to California is Accomplished via Rail and Ocean
Oregon Terminals
SF Bay Refineries Los Angeles Refineries
Based on Pat Perez of CEC.
Midwest Supply - Majority of Supply to California
Changes in Energy Use by Corn Ethanol: Midwest Use vs. California Use 40000
0 -20000 -40000 -60000 -80000
Corn EtOH in Midwest
Results are based ethanol in E85
Corn EtOH in CA via Rail
Petroleum
Fossil
Total Energy
Petroleum
Fossil
Total Energy
Petroleum
Fossil
-100000 Total Energy
Btu Change/EtOH Gallon
20000
Corn EtOH in CA via Ocean
Changes in Greenhouse Gas Emissions by Corn Ethanol: Midwest Use vs. California Use
GHG Change in Grams/EtOH Gallon
0
-1000
-2000
-3000
-4000
Results are based ethanol in E85
GHG
Corn EtOH in CA via Ocean
CO2
GHG
Corn EtOH in CA via Rail
CO2
GHG
CO2
Corn EtOH in Midwest
Energy Balance of Ethanol Results Among Studies 40,000 30,000
Lorenz and Morris
Net Energy Value (Btu/gallon)
20,000
Agri. Canada Wang et al.
Marland and Turhollow 10,000
Shapouri et al.
Shapouri et al. Kim and Wang Dale Graboski
0 -10,000
Ho Keeney and DeLuca
-20,000 -30,000 Pimentel Pimentel -40,000 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Ethanol GHG Emission Changes Among Studies 100% 80%
GHG Changes
60% 40% 20% 0% -20% -40% -60% -80% EPA (1989): E100
EPA (1989): E85
Ho Marland Delucchi Ahmed Delucchi Wang (1990): (1991): (1991): (1994): (1996): (1996): E100 E100 E100 E100 E95 E100
Wang (1996): E85
Wang (1997): E85
Agri. Delucchi Wang Can. (2001): (2003): (1999): E90 E85 E85
In long Run, Cellulosic Ethanol Could Play an Important Role in Energy Benefits PTW WTP
Baseline GV Gasoline HEV
Oil
Gasoline FCV Diesel HEV NG FTD HEV Natural Gas
NG Central H2 FCV Cellulosic EtOH FCV
Non-Fossil Domestic
Renewable Electrolysis H2 FCV 0
1,000
2,000
3,000
4,000
5,000
WTW Per-Mile Fossil Fuels Energy Use (Btu/mi.)
6,000
Cellulosic Ethanol Could Also Play an Important Role in GHG Reductions PTW WTP
Baseline GV Gasoline HEV Oil
Gasoline FCV Diesel HEV NG FTD HEV
Natural Gas
NG Central H2 FCV Cellulosic EtOH FCV
Non-Fossil Domestic
Renewable Electrolysis H2 FCV -300
-200
-100
0
100
200
300
WTW Per-Mile GHG Emissions (g/mi.)
400
500
Conclusions Any type of fuel ethanol helps substantially reduce transportation’s fossil energy and petroleum use Though studies now show that ethanol has positive 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 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 technologies and 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
