1. No category

Energy and Emissions Implications
of
Transportation Modes
Yanzhi Ann Xu, Ph.D.
School of Civil and Environmental Engineering
Georgia Institute of Technology
GT Energy Series: Energy and Urbanization
April 29, 2015
Mirror, mirror, on the wall,
What’s the best mode of them all?
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Image courtesy of the National Center for
Transportation Systems Productivity and Management
Level of Influence



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Individual mode choice
Policy making
– Transportation
– Fuel production and distribution
– Utilities
Multi-criteria evaluation at multiple scales
– Energy
– Emissions
– Health
Question 1
DRIVE OR FLY?
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Haobing Liu, Yanzhi “Ann” Xu, Nico Stockwell, Michael O. Rodgers, and Randall L. Guensler (Manuscript). A Comparative Analysis of Life-cycle
Energy and Emissions for Intercity Passenger Transportation in the U.S. for Regional Aviation, Intercity Bus, and Personal Vehicles.
Long-Distance Travel
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Single Aisle (SA) Jet vs. SUV: GHGs
grams/
Passenger
3.0E+05
2.5E+05
2.0E+05
SA Interplation curve
1.5E+05
Intersection
Point
1.0E+05
SUV_4Person
5.0E+04
SUV Interplation curve
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SA_80%Occupancy
0.0E+00
0
500
Trip Length (km)
1000
1500
Question 2
CAR, BUS, OR TRAIN?
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Xu, Y., F. Gbologah, G. Cernjul, A. Kumble, R. Guensler, and M. Rodgers (2013). “Comparison of fuel-cycle emissions per passenger mile from
multiple bus and rail technologies.” Proceedings of the 3rd International Conference on Urban Transportation Systems, pp. 204-216. Paris, France.
November 17-20, 2013.
Vehicle and Propulsion Systems
Blogs.discovermagazine.com
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Greencar.com
Wikipedia.org
Valleymetro.org
Surface Modes:
Emissions per Passenger Mile
Passenger loading
assumptions:
• Buses and vans:
Peak—40; average—9;
off-peak—5.
• AE heavy rail: Peak—
80% full; average—37%
full; off-peak—10% full.
Number of cars per
train: 10. Capacity per
car: 45.
• DE commuter rail:
Peak—80% full;
average—32% full; offpeak—10% full.
Number of cars per
train: 15. Capacity per
car: 90.
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Question 3
WHICH BUS?
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Xu, Y., F. Gbologah, D. Lee, H. Liu, M.O. Rodgers, and R. Guensler (in press). Assessment of Alternative Fuel and Powertrain Transit Bus Options
using Real-world Operations Data: Life-cycle Fuel and Emissions Modeling. Applied Energy.
Type of Bus Operations
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Urban Transit Route Duty Cycle
Speed in Miles Per Hour
80
60
40
20
0
0
12
500
1000
1500
Number of Seconds Elapsed
2000
2500
Comparison for Local Bus: GHGs
Emission Rate (kg/km)
3
2
Well-to-pump
Pump-to-wheel
0.4
0.4
0.4
0.4
0.4
0.1
0.4
0.1
0.1
0.4 0.4
0.4
0.4
0.3 0.3
2.4
1
1.7
1.7
1.4
1.4 1.4 1.2
1.6
1.9
1.6
1.9
2.0
1.7 1.6
1.9
1.7
2.1
1.8 1.8
1.3
0.7
ICE
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HEV
Atlanta, GA
EV
ICE
HEV
EV
San Francisco, CA
ICE
HEV
Phoenix, AZ
FCV
BEV
Series
Parallel
B20
CNG
0.0 0.0
Diesel
FCV
Series
Parallel
B20
CNG
0.0 0.0
Diesel
FCV
BEV
Series
Parallel
B20
CNG
Diesel
0.0 0.0
BEV
0
EV
Comparison for Local Bus: NOx
Well-to-pump
1.1
1.1
0.8
0.8
1.0
1.0
4.8 4.6 4.9 4.6
4.4
0.9
HEV
Atlanta, GA
EV
ICE
1.0
HEV
EV
San Francisco, CA
B20
ICE
Parallel
0.4
0.0
HEV
Phoenix, AZ
BEV
0.9
1.3
FCV
1.9
1.5
BEV
Series
Parallel
B20
CNG
1.0
Diesel
FCV
BEV
Parallel
B20
CNG
ICE
Series
1.1 1.0
0.7
0
4.4 4.2
4.0
Series
3.6 3.4 3.6 3.4
Diesel
1.0
0.8
0.7
0.8
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1.2
1.1
CNG
2
1.0
Diesel
4
Pump-to-wheel
FCV
Emission Rate (g/km)
6
EV
Comparison for Local Bus: PM2.5
0.4
Well-to-pump
Pump-to-wheel
Emission Rate (g/km)
0.3
0.2
0.4
0.3
0.3
0.1
0.1
0.1
Atlanta, GA
EV
ICE
0.1
HEV
EV
San Francisco, CA
ICE
Series
Parallel
B20
Series
Parallel
B20
CNG
Diesel
FCV
BEV
Series
Parallel
B20
CNG
Diesel
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HEV
0.1
0.0
0
ICE
0.1 0.1
CNG
0.1
Diesel
0.1 0.1
0.1
0.1 0.1
HEV
Phoenix, AZ
FCV
0.1
FCV
0.1
0.1
BEV
0.1
BEV
0.1
EV
Express Bus Route Duty Cycle
Speed in Miles per Hour
80
60
40
20
0
0
16
500
1000
1500
Number of Seconds Elapsed
2000
2500
Comparison for Express Bus: GHGs
Well-to-pump
Pump-to-wheel
3.0
Emission Rate (kg/km)
0.53
2.0
0.40
0.12
0.50
0.45
0.09
0.11
0.43
0.34
2.30
2.30
1.0
1.74
1.74
1.69
B20
Diesel CNG
2.18
2.18
1.60
1.28
0.0
Diesel CNG
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Atlanta, GA
B20
San Francisco, CA
Diesel CNG
B20
Phoenix, AZ
Comparison for Express Bus: NOx
Well-to-pump
Pump-to-wheel
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Emission Rate (g/km)
0.88
0.84
4
0.67
5.02
2
1.37
1.42
1.40
1.40
3.50
1.04
0.85
4.23
1.30
1.35
1.14
1.14
1.08
0.86
0
Diesel CNG
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B20
Atlanta, GA
Diesel CNG
B20
San Francisco, CA
Diesel CNG
B20
Phoenix, AZ
Comparison for Express Bus: PM2.5
Well-to-pump
Pump-to-wheel
0.4
Emission Rate (g/km)
0.3
0.2
0.1
0.10
0.09
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0.01
Diesel CNG
0.01
B20
Atlanta, GA
0.02
Diesel CNG
0.12
0.11
0.08
0.06
0.0
0.13
0.11
0.08
0.02
B20
San Francisco, CA
0.02
Diesel CNG
0.02
B20
Phoenix, AZ
Geographic Context
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Geographic Comparison
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CO2e (kg/mile)
6
San Francisco
5.9 5.7
5.6
5
Phoenix, AZ
5.4 5.2
5.0
4
Atlanta, GA
3.33.13.2
3.1
2.3
1.6
Parallel
Hybrid
Battery
Electric
3
2
4.8
4.1
3.7
1
0
Diesel
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CNG
Duty cycle used in example: New York Bus Cycle
H2 Fuel Cell
So…
WHAT’S THE ANSWER?
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Summary



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Complexity and uncertainty
– Type of application
– Operational characteristics
– Geographic context
– Optimization objectives
The broader picture: Sustainability & Resilience
Need for decision support tools
– Policy support tools
 Fuel and Emissions Calculator (FEC)
– Individual decision support tools
Questions and comments?
Please email [email protected]
Model website: fec.ce.gatech.edu
THANK YOU!
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