Using Argonne’s Modeling Software to Estimate Benefits of Alternative Fuel Vehicles
Andy BurnhamClean Cities University Workforce Development Program Webinar August 8, 2012
Outline
Life-Cycle Analysis and GREET Model Introduction
Example of Current Life-Cycle Analysis Research– Shale gas greenhouse gas emissions
GREET Fleet Footprint Calculator Introduction
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Life-Cycle Analysis and GREET Model Introduction
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From the Department of Energy’s Perspective Transportation Sector: Dual Challenges, Dual Approaches
Challenges– Oil use (energy security)– Greenhouse gas emissions (climate change)
Approaches– Vehicle efficiency– New transportation fuels
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Sources: Transportation Energy Data Book: Edition 27 and projections from the Early Release Annual Energy Outlook 2009.
U.S. Petroleum Production and Consumption 1970-2030
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1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
2030
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MarineRail
Cars
Air
Light Trucks
Heavy Trucks
U.S. ProductionOff-Road
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Highway Vehicles Contribute Significantly to U.S. Greenhouse Gas Emissions
2009 U.S. GHG emissions from fossil fuels = 5.2 Gt of CO2e (EPA 2011)6
Transportation33%
Industrial26%
Residential22%
Commercial19%
2009 Fossil Fuel GHG Emissions by End-Use Sector
Light Duty65%
Heavy Duty Trucks & Buses
21%
Air8%
Water2%
Rail2%
Pipelines2%Other
0%
2009 Fossil Fuel GHG Emissions by Transportation Mode
Life-Cycle Analysis for Vehicle/Fuel Systems Has Evolved in the Past 30 Years
Pursuing reductions in transportation petroleum use and GHG emissions requires for well-to-wheels (WTW) analyses
Pioneering WTW analyses began in 1980s– Early studies were motivated primarily by battery-powered EVs
Recent studies are motivated primarily by introduction of– New fuels such as cellulosic ethanol
– New vehicle technologies such as plug-in hybrids
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Life-Cycle Analysis of Vehicle and Fuel Systems in the GREET Model
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The GREET Model Estimates Energy Use, GHGs, and Criteria Pollutants
Separates energy use into:– Total energy
• Fossil energy• Renewable energy
Includes emissions of greenhouse gases – CO2, CH4, and N2O
Estimates emissions of six criteria air pollutants– VOC, CO, NOx, SOx, PM10, and PM2.5
The GREET model and its documents are available at Argonne’s website at http://greet.es.anl.gov/
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As an example, greenhouse gases are illustrated here
Taking the Results from GREET Can Provide Us with a Life-Cycle Comparison
Example of Current Life-Cycle Analysis Research
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Shale Gas Has Been Described as a Game Changing Resource, Which Could Permit Expanded NG Usage
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Source: EIA Annual Energy Outlook 2011
However Boom in Shale Gas Production Has Brought Attention to its Potential Environmental Impacts
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Large-scale production made possible due to recent advancements
– Horizontal drilling– Hydraulic fracturing
Environmental issues are beginning to be examined
– Water quality– Water quantity– Local air pollution– Greenhouse gas emissions
Source: EPA
EPA Has Recently Made Significant Changes to the Estimate of CH4 Emissions from the Natural Gas System
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Source: EPA – U.S. GHG Inventory Archive
Major changes include adding emissions from shale gas operations
Developed GREET shale gas pathway– Updated CH4 leakage estimates for conventional NG, petroleum, and coal
pathways
Focus of analysis was to estimate uncertainties and identify data gaps to provide insight to NG industry and government
Scope of Argonne’s Natural Gas Life-Cycle Analysis
Well InfrastructureNatural Gas Recovery
ProcessingTransmission and
DistributionEnd Use
(Photographs by J. Veil)
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Key Issues Affecting Natural Gas Life-Cycle Results
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Estimated Ultimate Recovery (EUR)
Shale Gas Well Completion Emissions
Conventional Gas Liquid Unloading Emissions
Global Warming Potential
End Use Efficiency
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Periodic Well Emissions Must be Allocated Over Lifetime NG Production
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Several key activities are estimated on a per-well basis– Lower the EUR, larger the impact
Shale gas EURs are highly uncertain as industry is in its infancy– Wide range for several plays
Conventional NG productivity is declining– Lower EUR than key shale plays
Low EUR Estimate (Bcf)
High EUR Estimate (Bcf)
Barnett 1.4 3.0Marcellus 1.4 5.2Fayetteville 1.7 2.6Haynesville 3.5 6.5Shale Per-Well Weighted Avg. 1.6 5.3
Conventional Avg. 0.8 1.217
Shale Gas Completions CH4 Emissions Could Be Large, But Industry Data Says Much is Recovered After hydraulic fracturing, a large volume of frac fluid & produced water
return to the surface– Flowback water contains NG, which can be vented, flared, or captured
EPA estimates “uncontrolled” CH4 emissions– Data used by EPA to calculate emissions have significant questions
EPA then calculates amount of NG flared and captured by industry practices using NESHAP regulations and NG STAR reporting
– Emissions were reduced by ~40% from 2005-2009– Lack of transparency as data is highly aggregated
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EPA’s Estimates Liquid Unloadings Account for Half of Uncontrolled CH4 Emissions From NG Production Accumulation of fluids in wet NG wells can eventually stop production
– Assumed to only occur in conventional wells (shale typically dry)– Removing liquids can be accomplished by several practices/technologies
Similar to issues with completion emissions, uncertainty arises from– Suitability of NG STAR data to calculate uncontrolled emissions– Lack of transparency regarding NG STAR reductions
Our examination found that liquid unloading emissions are potentially more significant than those from shale gas well completions
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Global Warming Potential is a Simple Measure to Compare Radiative Effects of Different Gases Need to choose a time-horizon when comparing emission impacts of
different fuels– Especially important when comparing contributions of short-lived gases
• CH4 has an atmospheric lifetime of ~12 years
IPCC recommends using a 100-year time-horizon when evaluating climate change mitigation policies
Other researchers have suggested a 20-year time-horizon should be examined
– Effects of CH4 emissions are amplified
We use the 100-year time-horizon in our analyses– Also present 20-year for comparison to other studies
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End-use Efficiency is a Key Factor for LCA Results
Compared to gasoline cars, NG cars have slightly lower fuel economy– Base case = 5% reduction
• Weight penalty of CNG storage tanks• Power loss due to oxygen displacement
– Use of direct injection and turbocharging can improve fuel economy and power
Compared to diesel transit buses, NG buses have moderately lower fuel economy
– Base case = 15% reduction• Spark-ignited engines have low efficiency at low speeds
– However NG spark-ignited engines have closed the gap on compression-ignition engines
• Primarily due to emission control strategies implemented for diesels to meet 2010 regulations
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CNGVs Using Fossil NG May Provide Small GHG Benefit, Improving Vehicle Efficiency Would Help
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Interesting result - base-case shale gas emissions are lower than conventional NG– Values overlap so can’t say one is actually better than the other
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Shale Gas and Conventional NG Summary
Estimates of CH4 leakage from NG have increased significantly
Shale gas completion emissions could be large in theory– However, industry reports that a significant amount is captured– Data is extremely limited and there is a lack of transparency
• Several efforts underway to get better data
Conventional NG liquid unloadings are potentially a larger source than shale gas completions
– Causes the greatest amount of uncertainty in our study
Shale and conventional NG may provide small GHG benefits for passenger cars and transit buses
– NGV efficiency is a key factor for improvement
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GREET Fleet Footprint Calculator Introduction
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GREET Fleet Allows Users to Estimate Petroleum and Carbon Footprints
Starting in 1998, US DOE and EPA co-sponsored Argonne to develop a tool, AirCRED, to assist Clean Cities coalitions to estimate ozone precursor and carbon monoxide emission credits from AFVs
– For use in State Implementation Plans (SIPs)
Now with the interest in measuring petroleum use and carbon/greenhouse gas emissions, Clean Cities sponsored Argonne to develop the GREET Fleet Footprint Calculator
– Developed in Microsoft Excel and uses simple spreadsheet inputs– Results are on WTW basis
This tool was designed for:– On-road-medium and heavy-duty vehicles– Off-road equipment
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GREET Fleet is Available for Download
Contains 12 fuel/vehicle types– Conventional: gasoline and diesel– Hybrid: diesel HEV– Alt. fuel: biodiesel (B20 and B100), ethanol (E85), CNG, LNG, LPG, electricity, gaseous
and liquid hydrogen• Additional simulation options include:
– Corn vs. cellulosic ethanol– North American NG vs. Non North American NG vs. Landfill Gas– Electricity mix (% coming from coal, natural gas, nuclear, etc.)– Several hydrogen production pathways
GREET Fleet is based off the current public version of GREET
You can find GREET Fleet and its user manual at:http://greet.es.anl.gov/fleet_footprint_calculator
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GREET Fleet Tutorial
Comparing On-Road Vehicle Technologies for Potential Acquisitions
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GREET Fleet Tutorial – Comparing On-Road Vehicle Technologies for Potential Acquisitions
First step: choose how to calculate footprint on ‘On-road fleet sheet’– Choose “Option 1” to calculate using fleet size, VMT & fuel economy
1. Method to Calculate On-Road Fleet's Petroleum Energy Use and GHG Footprint1 1 - Fleet size, vehicle miles traveled, and fuel economy
2 - Fuel use (skip to question 5)
Second step: enter the amount of vehicles– In this demo we will compare diesel transit buses to: diesel hybrid, B20, &
CNG
2. The Number of Each Type of Vehicle in On-Road Fleet
Gasoline DieselDiesel
HEVBiodiesel
(B20)Biodiesel
(B100)Ethanol
(E85)
Compressed Natural Gas
(CNG)School Bus 0 0 0 0 0 0 0Transit Bus 0 20 20 20 0 0 20Shuttle/Paratransit Bus 0 0 0 0 0 0 0Waste Hauler 0 0 0 0 0 0 0Street Sweeper 0 0 0 0 0 0 0Delivery Step Van 0 0 0 0 0 0 0Transport/Freight Truck 0 0 0 0 0 0 0Medium/Heavy Duty Pickup Truck 0 0 0 0 0 0 0Maintenance Utility Vehicle 0 0 0 0 0 0 0Other 0 0 0 0 0 0 0
Note: Several fuels to the right of CNG are not shown for clarity in this presentation 28
GREET Fleet Tutorial – Comparing On-Road Vehicle Technologies for Potential Acquisitions
Third step: enter the annual mileage3. The Average Annual Vehicle Miles Traveled by Each Vehicle Type
Gasoline DieselDiesel
HEV B20 B100 E85 CNGSchool Bus 30,000 30,000 30,000 30,000 30,000 30,000 30,000Transit Bus 30,000 50,000 50,000 50,000 30,000 30,000 50,000Shuttle/Paratransit Bus 30,000 30,000 30,000 30,000 30,000 30,000 30,000Waste Hauler 23,400 23,400 23,400 23,400 23,400 23,400 23,400Street Sweeper 12,600 12,600 12,600 12,600 12,600 12,600 12,600Delivery Step Van 16,500 16,500 16,500 16,500 16,500 16,500 16,500Transport/Freight Truck 80,000 80,000 80,000 80,000 80,000 80,000 80,000Medium/Heavy Duty Pickup Truck 11,400 11,400 11,400 11,400 11,400 11,400 11,400Maintenance Utility Vehicle 5,000 5,000 5,000 5,000 5,000 5,000 5,000Other 30,000 30,000 30,000 30,000 30,000 30,000 30,000
4. The Average Fuel Economy for Each Vehicle Type in the On-Road Fleet (miles per gasoline gallon equivalent)
Gasoline DieselDiesel
HEV B20 B100 E85 CNGSchool Bus 6.0 7.0 8.5 7.0 7.0 6.0 6.0Transit Bus 2.5 3.0 3.8 3.0 3.0 2.5 2.5Shuttle/Paratransit Bus 7.0 8.0 10.0 8.0 8.0 7.0 7.0Waste Hauler 2.0 2.5 3.0 2.5 2.5 2.0 2.0Street Sweeper 3.0 4.0 5.0 4.0 4.0 3.0 3.0Delivery Step Van 12.0 15.0 18.5 15.0 15.0 12.0 12.0Transport/Freight Truck 5.0 6.0 7.5 6.0 6.0 5.0 5.0Medium/Heavy Duty Pickup Truck 9.0 11.0 13.5 11.0 11.0 9.0 9.0Maintenance Utility Vehicle 20.0 25.0 31.0 25.0 25.0 20.0 20.0Other 2.5 3.0 3.8 3.0 3.0 2.5 2.5
Fourth step: enter the fuel economy
Note: Several fuels to the right of CNG are not shown for clarity in this presentation 29
Fifth step: adjust fuel production assumptions if needed6. Fuel Production Assumptions
Ethanol Feedstock Source 1 1 - Corn 2 - Switchgrass
CNG Feedstock Source 1 1 - North American NG 2 - Non-North American NG
LNG Feedstock Source 1 1 - North American NG 2 - Non-North American NG
LPG Feedstock Source NG Petroleum60% 40%
Source of Electricity for On-Road Electric Vehicles and H2 Electrolysis1 1 - Average U.S. Mix
2 - Average Northeast Mix 3 - Average California Mix 4 - User Defined (go to 'Specs' sheet)
G.H2 Production Process 1 1 - Refueling Station SMR (On-site) 2 - Central Plant SMR (Off-site) 3 - Refueling Station Electrolysis (On-site)
L.H2 Production Process 1 1 - Refueling Station SMR (On-site) 2 - Central Plant SMR (Off-site) 3 - Refueling Station Electrolysis (On-site)
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GREET Fleet Tutorial – Comparing On-Road Vehicle Technologies for Potential Acquisitions
Final step: view petroleum and greenhouse gas results7. Results of On-Road Fleet's Petroleum Usage (barrels)
Gasoline Diesel Diesel
HEV B20 B100 E85 CNG School Bus 0.0 0.0 0.0 0.0 0.0 0.0 0.0Transit Bus 0.0 7687.7 6069.3 6263.0 0.0 0.0 50.8Shuttle/Paratransit Bus 0.0 0.0 0.0 0.0 0.0 0.0 0.0Waste Hauler 0.0 0.0 0.0 0.0 0.0 0.0 0.0Street Sweeper 0.0 0.0 0.0 0.0 0.0 0.0 0.0Delivery Step Van 0.0 0.0 0.0 0.0 0.0 0.0 0.0Transport/Freight Truck 0.0 0.0 0.0 0.0 0.0 0.0 0.0Medium/Heavy Duty Pickup Truck 0.0 0.0 0.0 0.0 0.0 0.0 0.0Maintenance Utility Vehicle 0.0 0.0 0.0 0.0 0.0 0.0 0.0Other 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Fuel Total 0.0 7,687.7 6,069.3 6,263.0 0.0 0.0 50.8
On-Road Fleet Total 20,070.8 barrels of oil
8. Results of On-Road Fleet's Greenhouse Gas Emissions (short tons CO2-equivalent)
Gasoline Diesel Diesel
HEV B20 B100 E85 CNG School Bus 0.0 0.0 0.0 0.0 0.0 0.0 0.0Transit Bus 0.0 4,186.1 3,304.8 3560.8 0.0 0.0 4014.0Shuttle/Paratransit Bus 0.0 0.0 0.0 0.0 0.0 0.0 0.0Waste Hauler 0.0 0.0 0.0 0.0 0.0 0.0 0.0Street Sweeper 0.0 0.0 0.0 0.0 0.0 0.0 0.0Delivery Step Van 0.0 0.0 0.0 0.0 0.0 0.0 0.0Transport/Freight Truck 0.0 0.0 0.0 0.0 0.0 0.0 0.0Medium/Heavy Duty Pickup Truck 0.0 0.0 0.0 0.0 0.0 0.0 0.0Maintenance Utility Vehicle 0.0 0.0 0.0 0.0 0.0 0.0 0.0Other 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Fuel Total 0.0 4,186.1 3,304.8 3,560.8 0.0 0.0 4,014.0
On-Road Fleet Total 15,065.6 short tons of GHG emissions
Vehicle Total
0.020070.8
0.00.00.00.00.00.00.00.0
Note: Several fuels to the right of CNG are not shown for clarity in this presentation
Vehicle Total
0.015065.6
0.00.00.00.00.00.00.00.0
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GREET Fleet Tutorial – Comparing On-Road Vehicle Technologies for Potential Acquisitions
Final Thoughts
When examining your fleet’s petroleum and carbon footprint it is best to understand both the direct impacts from operating the vehicle and the indirect impacts that resulted from producing and transporting the fuel
– The upstream (well-to-pump) activities can significantly affect a vehicle’s footprint, especially those that use alternative fuels
The thought of trying to account for all the issues that go into calculating a vehicle’s footprint may be overwhelming
– However, there are easy-to-use yet robust tools that can help
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Thank you!!!
Argonne National Laboratory’s work is supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy
For additional information contact:[email protected]
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