Automotive Technologies and Fuel Economy Policy Don MacKenzie MIT Engineering Systems Division Sloan Automotive Laboratory November 18, 2010 11/18/10
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Outline • Technology overview • Policy overview
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www.ecologicliving.ca
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Technologies for Higher Fuel
Economy
Credit for slides: Irene Berry
SM Mechanical Engineering / Technology and Policy, 2010
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We frame vehicle design in terms of range
and performance goals
Range
Performance
Over a Standard Drive Cycle 0-60 mph
Acceleration Time
�
Energy Specification
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�
Power Specification
4
Range depends on the energy required at
the wheels and vehicle efficiency
2005 3.0-L Toyota Camry over UDDS drive cycle
Standby:
8%
Fuel Tank:
100%
Aero:
3%
16%
Engine
Driveline
13%
Engine Loss
76%
Braking:
6%
Driveline
Losses:
3%
770%
Rolling:
4%
100%
vehicle efficiency over
11/18/10
UDDS
cycle: 13%
~ 165 5Wh/km
Performance depends on the peak power of
the vehicle
Limited region of high efficiency
Peak power
90
80
Power with wide open throttle
280 (30.6%)
Engine power (kW)
70
260 (33%)
60
40
30
350 (24.5%)
)
%
50
bsfc (g/kWh)
(efficiency)
.3
34
0(
Engine map of spark
ignition (SI) internal
combustion engine
(ICE)
500 (17.1%)
25
310 (27.7%)
270 (31.8%)
400 (21.4%)
20
10
1000 (8.57%)
600 (14.3%)
0
500
1000
1500
2000
Typical operating conditions
on UDDS drive cycle
2500
3000
700 (12.2%)
3500
Engine speed (rpm)
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4000
800 (10.7%)
4500
5000
5500
Lowest efficiency is at low
loads and high speeds
Image by MIT OpenCourseWare. Adapted from Ehsani, Mehrdad, et al.
Modern Electric, Hybrid Electric, and Fuel Cell Vehicles: Fundamentals,
Theory, and Design. CRC Press, 2005. ISBN: 9780849331541.
So, we want to increase efficiency while meeting design goals 90
80
Power with wide open throttle
280 (30.6%)
1. Reduce load (energy required at
the wheels)
Engine power (kW)
70
260 (33%)
60
350 (24.5%)
)
%
4.3
50
0
25
bsfc (g/kWh)
(efficiency)
40
30
(3
500 (17.1%)
310 (27.7%)
270 (31.8%)
400 (21.4%)
20
2. Increase powertrain efficiency
10
1000 (8.57%)
800 (10.7%)
600 (14.3%) 700 (12.2%)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
Engine speed (rpm)
1. Increase efficiency of engine
90
80
2. Shift engine operating points
280 (30.6%)
70
Engine power (kW)
3. Use smaller engine (downsize)
Power with wide open throttle
260 (33%)
60
50
40
350 (24.5%)
0(
25
bsfc (g/kWh)
(efficiency)
.3%
34
)
500 (17.1%)
310 (27.7%)
270 (31.8%)
30
400 (21.4%)
20
10
0
500
600 (14.3%) 700 (12.2%)
1000
1500
2000
2500
3000
3500
4000
800 (10.7%)
4500
1000 (8.57%)
5000
Engine speed (rpm)
Image by MIT OpenCourseWare. Adapted from Ehsani, Mehrdad, et al.
Modern Electric, Hybrid Electric, and Fuel Cell Vehicles: Fundamentals,
Theory, and Design. CRC Press, 2005. ISBN: 9780849331541.
11/18/10
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[Ehsani et al 2004]
5500
Reducing the load at the wheels reduces fuel consumption • Reduce weight
• Reduce aerodynamic drag
• Reduce accessory loads
Please see any description of Volkswagen's 1-Litre
concept car and Siuru, Bill. "5 Facts: Vehicle Aerodynamics."
GreenCar, October 13, 2008.
�
These reductions also allow for downsizing 11/18/10
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Diesel engines are more efficient, but
heavier and more expensive
Compression Ignition (vs. Spark Ignition)
• Only air is compressed
– Higher compression ratio
• Fuel is injected into the compressed air
and self-ignites
– Direct injection
Diesel (vs. Gasoline) Fuel
• Higher energy content
• Higher emissions from combustion
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These engine technologies increase engine
efficiency and/or power
Technology
Mechanism
Efficiency gain
Variable valve timing
Optimizes efficiency for
both high and low engine
speeds
5%
Cylinder deactivation
Increases low load
efficiency
7.5%
Turbo- or super­
charge
Increases engine power
per size: allows downsizing
7.5%
Direct Injection
More efficient fuel delivery
and combustion
5-10%
Advanced aftertreatment
Allows engine to produce
more emissions
www.fueleconomy.gov
11/18/10
N/A
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These transmission technologies allow
better control of engine speed
Technology
Mechanism
Efficiency gain
CV transmission
Optimize engine speed
6%
Dual-clutch
transmission
Optimize engine speed
7%
www.fueleconomy.gov
11/18/10
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Different combustion cycles also offer
efficiency improvements
Technology
Mechanism
Efficiency gain
Miller cycle
Trade power for efficiency
5%
Atkinson cycle
Trade power for efficiency
5%
HCCI
More efficient at low load
7.5%
www.fueleconomy.gov
11/18/10
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There are additional opportunities for energy savings through hybridization Micro+ Hybrids
Eliminates
Standby:
8%
Fuel Tank:
100%
Aero:
3%
16%
Engine
Engine Loss
76%
Full Hybrid Reduces via
engine downsizing
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shifts engine operating
Driveline
Driveline
Losses:
3%
13%
Rolling:
4%
Braking:
6%
Regenerative Braking
Reduces
13
Hybrid optimization shifts the engine operating points to higher efficiency Torque with wide
open throttle
20
30 40
50
60
70
80 90
Power (kW)
982
Use electric power to assist
Brake torque (Nm)
200
sfc
(ghWh)
(efficiency)
785
250 (34.3%)
Engine only
260 (33.3%)
150
100
270 (31.89%)
Use electric to
load the engine
to recharge
0
350 (24.5%)
600 (14.3%)
500
400 (21.4%)
196
Electric only
700 (12.4%)
0
393
310 (27.7%)
500 (17.1%)
50
589
280 (30.6%)
Brake mean effective pressure (kPa)
10
250
800 (10.7%) 1000 (8.57%)
0
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500
Engine speed (rpm)
[Ehsani et al 2004]
Image by MIT OpenCourseWare. Adapted from Ehsani, Mehrdad, et al.
Modern Electric, Hybrid Electric, and Fuel Cell Vehicles: Fundamentals,
Theory, and Design. CRC Press, 2005. ISBN: 9780849331541.
11/18/10
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(kW of motor power)
Electric Power
Hybrids and electric vehicles are classified
by degree of electrification
Plug-in
Hybrid
Electric
Vehicle
(PHEV)
Full
Hybrid
Mild
Hybrid
Battery Electric
Vehicle (BEV)
Can plug-in to
recharge
Can have “electric
only” range
Micro
Hybrid
Electric Energy
(watt-hours of battery capacity)
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Hybrids achieve fuel savings through
multiple efficiency mechanisms
40% lower fuel consumption
35% lower fuel consumption
Data from: An et al 2001
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Battery electric vehicle are fully electric,
which has both pros and cons
Advantages
• Electricity
• Any energy source
• Potentially less emissions
• Single emissions source
• Electric drive
• More energy efficient • Higher low-speed torque
• Lower operating costs • Less maintenance
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Disadvantages • Batteries
• Long charge times • High cost
• Low energy content relative to gasoline • Limited range
• Concerns over life • Electric drive
• Different operating and
driving feel
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To compare different fuels, consider well-to­
wheels energy and emissions
Well-to-Tank
~30% Efficient
Tank-to-Wheel
~80% Efficient
~24% Efficient
~16% Efficient
~80% Efficient
~20% Efficient
Image from "Getting Around Without Gasoline." Northeast Sustainable Energy Association, 1995.
[http://www.nesea.org/]
11/18/10
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Automotive Fuel Economy Policy in
the U.S.
Overview of Institutions and Policies Federal
DOT:
Fuel Economy
Standards
IRS:
Fuel Taxes
State
EPA:
CARB:
GHG Standards
GHG Standards
IRS:
Gas Guzzler Tax
State
Governments:
Fuel Taxes
Feebates
Cap & Trade
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Corporate Average Fuel Economy
•
Administered by National Highway Traffic Safety Administration
(NHTSA, part of the DOT)
•
Sets minimum average level of fuel economy that new lightduty* vehicles sold by each manufacturer must meet each year
•
Fuel economy is based on a test procedure from the 1970s
•
~30% higher than real-world values or “window sticker” estimates
* Light-Duty means a gross vehicle weight rating ≤ 8,500 lbs.
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2
1
http://www.cornerstonemcm.org/Cafe_Outdoor_Light_Box.jpg
Corporate Average Fuel Economy
• Separate standards & calculations for cars and “light trucks”
Fuel Economy (MPG)
60
2025 Proposed
Range
50
40
2020 Mandate
EISA 2007
30
20
10
0
1970
1980
1990
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2000
2010
2020
2030
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The MPG Distortion
• MPG is inverse of metric that matters: fuel consumption
2025 Prop
Range Fuel Consumption (Gal/100mi)
8
7
6
5
4
2020 Mandate
EISA 2007
3
2025 Proposed
Range
1.7-2.2 gal/100mi
2
1
0
1970
1980
1990
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2000
2010
2020
2030
23
Corporate Average Fuel Economy
Some Details
•
Electric Vehicle Credited MPG = (Energy-Equivalent MPG) / 0.15
•
Credits for overcompliance can be “banked” from past 5 years or
“borrowed” from next 3 years
•
Flexible-fuel and bi-fuel vehicles capable of using alternative fuels
earn ~60% bonus credit on fuel economy rating
•
•
Total benefit capped at 1.2 mpg each year
Penalty for noncompliance = $55/mpg/vehicle
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4
http://gas2.org/files/2009/07/flexfuel.jpg
Corporate Average Fuel Economy
Recent Changes
•
•
NHTSA now required to set attribute-based standards
•
Different standards for each manufacturer, based on product mix
•
Intended to reduce equity issues of regulatory cost
•
Effectively negates downsizing as a compliance strategy
Credits can now be traded between fleets and between
manufacturers
•
Subject to certain restrictions
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2
5
http://gas2.org/files/2009/07/flexfuel.jpg
Corporate Average Fuel Economy Size-Based Standards
Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules
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Corporate Average Fuel Economy Size-Based Standards
Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules
11/18/10
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Corporate Average Fuel Economy
How Standards are Set
• Cost-benefit analysis including discounted lifetime fuel expenses,
estimated technology costs, monetized values of non-financial
costs and benefits
• Applies efficiency-enhancing technologies in order of cost
effectiveness, subject to judgment-based constraints
• Equalizes marginal cost of more technology with marginal benefit
World’s biggest black box?
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2
8
Vehicle GHG Standards
•
(2002) “Pavley” GHG standards required by California Assembly
Bill 1493, to be implemented by California Air Resources Board
•
•
•
•
•
13 other states opt in to California’s standards under Clean Air Act
provisions
(2004) Auto manufacturers, trade associations, dealers sue,
citing principle that GHG regulation is tantamount to fuel
economy regulation, explicitly preempted by CAFE law
(2007) Supreme Court rules in Massachusetts v EPA that GHGs
are pollutants under the Clean Air Act
(2007) Bush Administration denies California “waiver” from
federal preemption (waiver needed to implement regulations)
(2009) Obama administration grants waiver, brokers truce
between manufacturers and states, announces harmonized state
& federal standards. Dealers continue to sue.
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http://epa.gov/otaq/climate/regulations.htm
http://www.edf.org/page.cfm?tagID=15503
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Vehicle GHG Standards Electric vehicles
assumed to have zero
emissions, up to first
200,000-300,000
produced.
Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules
11/18/10
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Gasoline Taxes
• • Cents per Gallon 60
10% increase in fuel price � 3.3% increase in MPG (long term)
To go from 26 � 35 MPG:
• • • Need gas to go from $2/gal to ~$5/gal
Annual gasoline bill increases by ~$1000/year for new cars
Annual gasoline bill increases by ~$1800/year for older cars
50
40
30
State
20
Federal
10
0
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http://www.gaspricewatch.com/usgastaxes.asp
Gas Guzzler Tax • Applies only to cars, not light trucks 12.5 mpg
22.5 mpg
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Other Policies
• Feebates
• • • • Cap & Trade
• • • Fee + Rebate, purchase incentive system
Greater cost certainty, less emissions certainty relative to CAFE
Recently adopted in France, initial results promising
Would effectively be a gas tax
$10 / tonne CO2 ~ $0.10 / gallon
Cash for Clunkers
• Not energy/carbon policy
• • • $200+ per ton of avoided emissions (Knittel, 2009)
More effective if goals are criteria pollutant emissions
Maybe effective as economic stimulus
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Advantages and Disadvantages of Policies Pros
Cons
Standards
+Emissions certainty
+Well-established
-Rebound effect takes back
~10% of benefits, increases
other externalities
-Uncertain costs
-No incentive to exceed
standard
-Disparate impact on
manufacturers
Incentives
+Cost certainty
+Stimulates continuous
improvement
-Little experience
-Reduced operating cost �
rebound effect
Fuel Taxes
+Drives reductions
throughout system
-Hits consumers hardest,
especially w/ older vehicles
-Politically difficult
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Current Issues…
…being dealt with
• How to include electric vehicles & plug-in hybrids
• State versus Federal regulation
… and not being dealt with
• How to sustain increases in fuel economy over the long term
• Cost to manufacturers of meeting regulations
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Introduction to Sustainable Energy
Fall 2010
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