Real-World Activity and Fuel Use
of Diesel and CNG Refuse Trucks
1
2
Gurdas Sandhu1
H. Christopher Frey1
Shannon Bartelt-Hunt2
Elizabeth Jones2
@ 2014 PEMS International Conference & Workshop » April 3-4 » Riverside, California
2
Waste Collection in U.S.
 ~ 250 million tons of municipal solid waste generated
each year
 ~ 140,000 refuse trucks for collection and
transportation
 Trucks average 25,000 miles per year
 Typical fuel economy of 2 to 3 mpg of diesel
3
Motivation
 Very few studies that report real-world diesel or
natural gas refuse truck duty cycles and fuel use
rates.
 No study that compares real-world duty cycles and
fuel use rates between refuse truck configurations.
4
Study Overview
“Include refuse truck configurations, model years &
emissions control devices, and fuels typical to the U.S.
waste collection industry.”




24 Trucks (18 diesel, 6 CNG)
Roll-off, Front-loader, and Side-loader configurations
Model Years: 2003 to 2012
Fuels: Ultra Low Sulfur Diesel (ULSD) and Compressed
Natural Gas (CNG)
5
Research Questions
1. What are the real-world duty cycles of roll-off, frontloader, and side-loader refuse trucks?
2. What are the real-world fuel use rates of diesel rolloff, front-loader, and side-loader refuse trucks?
3. What are the real-world fuel use rates of CNG frontloader and side-loader refuse trucks?
6
Roll-off Refuse Truck Activity
1
2
3
4
7
Front-loader Refuse Trucks Activity
1
2
3
4
8
Side-loader Refuse Trucks Activity
1
2
3
4
9
Measured Diesel Roll-off Trucks
Truck
Year
Chassis
Make
Model
Year
Make
Engine
Model
Displ. (L)
Hp
Emissions Controls
Mileage
RO-1
RO-2
RO-3
RO-4
RO-5
RO-6
2005
2006
2007
2007
2012
2012
Mack
Mack
Mack
Mack
Mack
Mack
CV713 CV713 CV713 CV713
GU 713
GU 713
2005
2005
2006
2006
2012
2012
Mack
Mack
Mack
Mack
Mack
Mack
AMI-370 AMI-335 AMI-335 AMI-335 MP7-405M
MP7-405M
11.9
11.9
11.9
11.9
11.0
11.0
405
365
365
365
405
405
EGR
EGR
EGR
EGR EGR,DPF, SCR EGR, DPF, SCR
362,037 445,734 320,805 303,635
81,588
81,903
DPF - Diesel Particulate Filter; EGR - Exhaust Gas Recirculation; SCR – Selective Catalytic Reduction
10
Measured Diesel Front-loader Trucks
Truck
Year
Chassis
Make
Model
Year
Make
Engine
Model
Displ. (L)
Hp
Emissions Controls
Mileage
FL-1
FL-2
FL-3
FL-4
FL-5
2004
2005
2008
2008
2010
Mack
Mack
Autocar
Mack
Autocar
MR6885 MR6885
WX64
MRU 613 Xpeditor
2004
2004
2006
2008
2007
Mack
Mack
Cummins
Mack
Cummins
AI-350
AI-350 ISM-320V MP7 325M ISL-365
12.0
12.0
10.8
11.0
8.9
350
350
320
325
365
EGR
EGR
EGR
EGR, DPF EGR, DPF
284,003 267,971 184,934
117,691
50,033
DPF - Diesel Particulate Filter; EGR - Exhaust Gas Recirculation
FL-6
2010
Autocar
Xpeditor
2007
Cummins
ISL-365
8.9
365
EGR, DPF
41,017
11
Measured Diesel Side-loader Trucks
Truck
SL-1
SL-2
SL-3
SL-4
Year
2003
2003
2008
2009
Chassis
Make
Mack
Mack
Freightliner
Mack
Model LE 613 LE 613
M2 106
LEU 613
Year
2003
2003
2008
2008
Make
Mack
Mack Detroit Diesel
Mack
Engine
Model AI-300A AI-300A MBE 900
MP7-325M
Displ. (L)
12.0
12.0
7.2
11.0
Hp
325
325
250
325
Emissions Controls
EGR, DPF
EGR, DPF
Mileage 236,913 292,135
108,814
88,781
SL-5
2010
Freightliner
M2
2010
Cummins
ISC-300
8.3
300
EGR, DPF
75,480
SL-6
2012
Freightliner
M2
2012
Cummins
ISC-300
8.3
300
EGR, DPF, SCR
40,097
DPF - Diesel Particulate Filter; EGR - Exhaust Gas Recirculation; SCR – Selective Catalytic Reduction
12
Measured CNG Trucks
Truck
Year
Chassis
Make
Model
Year
Make
Engine
Model
Displ. (L)
Hp
Emissions Controls
Mileage
Front-loader
FLC-1
FLC-2
FLC-3
2013
Mack
MRU633
2012
Cummins
ISLG-320
8.9
320
EGR, TWC
27,670 35,551 30,534
Side-loader
SLC-1
SLC-2
SLC-3
2012
Autocar
ACX64
2012
Cummins
ISLG-320
8.9
320
EGR, TWC
23,197 25,177 25,317
EGR - Exhaust Gas Recirculation; TWC – Three Way Catalyst
13
CNG Fuel System
1 diesel gallon equivalent (DGE)
of CNG costs ~ $1.80
Full fuel tank: 3600 psi
At engine inlet: 70-150 psi
Inside engine: 40-70 psi
14
Instrumentation
PEMS: GlobalMRV Axion
Exhaust Probes
ECU Readout
GPS units: Garmin 76CSx
15
Data Collected
 Exhaust pollutants: Carbon Dioxide (CO2), Carbon
Monoxide (CO), Hydrocarbons (HC), Nitric Oxide
(NO), and Particulate Matter (PM).
 Engine Data: Vehicle Speed (kph), Engine Speed
(rpm), Intake Air Temperature (oC), Intake Manifold
Pressure (kPa), Fuel Use Rate (L/hr), Engine Load (%),
Torque (%), and Exhaust Temperature (oC).
 Location Data: Latitude, Longitude, Elevation (m)
16
Time Alignment Example: CO2 vs. Fuel Use
17
Correlation Coeff Example: CO2 vs. Fuel Use
18
MOVES Scaled Tractive Power
rt
Avt  Bv  Cv  mvt (at  g
)
100
STPt 
f scale
2
t
STPt
A
B
C
at
g
m
rt
vt
fscale
3
t
= scaled tractive power at time t, skW
= rolling resistance coefficient [kW-s/m] {1.41705}
= rotational resistance coefficient [kW-s2/m2] {0}
= aerodynamic drag coefficient [kW-s3/m3] {0.003572}
= vehicle acceleration at time t [m/s2]
= acceleration due to gravity [9.81 m/s2]
= vehicle mass [metric ton] {20.6845}
= road grade at time t [%]
= vehicle speed at time t [m/s]
= scaling factor, 17.1 unitless
19
....
36
1 mph ≤ Speed < 25 mph
25 mph ≤ Speed < 50 mph
50 mph ≤ Speed
30
24
0
Coasting, STP < 0
6
Coasting, STP < 0
12
Idling
18
Decelerating
Scaled Tractive Power, skW
MOVES Operating Mode Definition
0 1 11 12 13 14 15 16 21 22 23 24 25 27 28 29 30 33 35 37 38 39 40
MOVES Operating Mode
20
Activity Overview for Diesel Trucks
Roll-off
Front
loader
Side
loader
Total
50
48
46
144
Miles Driven
870
780
555
2,205
Fuel Used (gal)
199
285
210
694
39
660
4,200
4,900
165
150
50
365
1Hz QA Data (hours)
Trash Cans Picked
Trash Collected (tons)
21
Activity Overview for CNG Trucks
Front
loader
Side
loader
Total
30
20
50
Miles Driven
324
169
493
Fuel Used (DGE)
145
116
261
Trash Cans Picked
416
2110
2526
Trash Collected (tons)
105
28
133
1Hz QA Data (hours)
22
Route of Roll-off 3
170 miles
7 cans
52 tons
23
Route of Front-loader 2
157 miles
110 cans
28.3 tons
24
Route of Side-loader 4
88 miles
1100 cans
18.3 tons
25
Speed Trace for One Trip of Roll-off 3
U = Urban (arterial) driving, no trash collection; H = Highway driving; L = Landfill; TC = Trash Collection
80
Speed (mph)
U
H U
TC
U H
U
L
1 can
60
40
20
0
0
1000
2000
3000
Time (seconds)
4000
5000
26
Speed Trace for One Trip of Front-loader 2
U = Urban (arterial) driving, no trash collection; H = Highway driving; L = Landfill; TC = Trash Collection
80
Speed (mph)
U H U
TC
U H U L
25 cans
60
40
20
0
0
2000
4000
6000
8000
Time (seconds)
10000
12000
27
Speed Trace for One Trip of Side-loader 4
U = Urban (arterial) driving, no trash collection; H = Highway driving; L = Landfill; TC = Trash Collection
80
Speed (mph)
U H U
TC
U
L
450 cans
60
40
20
0
0
4000
8000
Time (seconds)
12000
16000
28
80
Idling
Within a speed range, higher modes represent greater engine power demand
60
1 mph ≤ Speed < 25 mph
25 mph ≤ Speed < 50 mph
50 mph ≤ Speed
NCSU Diesel Front-L RT
40
20
NCSU CNG Front-L RT
Decelerating
% Time Spent in OpMode
Comparison of Duty Cycles: Diesel vs CNG
NCSU Diesel Side-L RT
NCSU CNG Side-L RT
0
0 1 11 12 13 14 15 16 21 22 23 24 25 27 28 29 30 33 35 37 38 39 40
MOVES Operating Mode
29
80
Idling
Within a speed range, higher modes represent greater engine power demand
60
1 mph ≤ Speed < 25 mph
25 mph ≤ Speed < 50 mph
50 mph ≤ Speed
NCSU Roll-off RT
NCSU Front-loader RT
40
20
Decelerating
% Time Spent in OpMode
Comparison of Duty Cycles: NCSU vs Literature
NCSU Side-loader RT
Central Business District
New York Garbage Truck
0
0 1 11 12 13 14 15 16 21 22 23 24 25 27 28 29 30 33 35 37 38 39 40
MOVES Operating Mode
30
Example: Modal Fuel Use Rates for RO-3
25
Within a speed range, higher modes represent greater engine power demand
1 mph ≤ Speed < 25 mph
25 mph ≤ Speed < 50 mph
50 mph ≤ Speed
15
10
5
Decelerating
Idling
Fuel Use (g/s)
20
0
0 1 11 12 13 14 15 16 21 22 23 24 25 27 28 29 30 33 35 37 38 39 40
MOVES Operating Mode
31
Diesel Fuel Use Rates for Observed Cycles
Roll-off
Truck
RO-1
RO-2
RO-3
RO-4
RO-5
RO-6
Front-loader
Fuel
g/s
mi/gal
3.0
4.5
2.6
4.0
3.6
4.0
3.1
3.9
2.4
6.0
2.5
4.9
Average:
Max/Min:
4.6
1.5
Truck
FL-1
FL-2
FL-3
FL-4
FL-5
FL-6
Fuel
g/s
mi/gal
5.1
3.2
3.8
2.6
4.9
2.1
3.5
2.4
4.5
2.6
3.8
2.3
Average:
Max/Min:
2.6
1.5
Side-loader
Truck
SL-1
SL-2
SL-3
SL-4
SL-5
SL-6
Fuel
g/s
mi/gal
3.8
2.8
3.9
2.1
2.5
3.3
4.0
2.0
2.1
3.1
2.0
4.2
Average:
Max/Min:
2.9
2.1
32
Diesel Fuel Use Rates for Average Cycle
Roll-off
Truck
RO-1
RO-2
RO-3
RO-4
RO-5
RO-6
Front-loader
Fuel
g/s
mi/gal
2.9
4.4
3.1
4.2
3.3
3.9
3.0
4.4
2.4
5.5
2.6
4.9
Max/Min:
1.4
Truck
FL-1
FL-2
FL-3
FL-4
FL-5
FL-6
Fuel
g/s
mi/gal
4.3
2.5
4.1
2.6
4.5
2.4
4.0
2.8
4.4
2.5
4.3
2.5
Max/Min:
1.2
Side-loader
Truck
SL-1
SL-2
SL-3
SL-4
SL-5
SL-6
Fuel
g/s
mi/gal
3.5
2.3
4.2
2.0
2.3
3.6
3.7
2.2
2.6
3.2
2.0
4.0
Max/Min:
2.0
33
CNG Fuel Use Rates for Observed Cycles
Front-loader
Truck
FLC-1
FLC-2
FLC-3
Fuel
g/s mi/DGE
3.4
2.3
3.7
2.6
3.5
2.1
Side-loader
Truck
SLC-1
SLC-2
SLC-3
Fuel
g/s mi/DGE
2.6
1.1
3.7
2.0
2.4
1.5
Average:
Max/Min:
2.3
1.2
Average:
Max/Min:
1.5
1.8
Diesel Avg:
2.6
Diesel Avg:
2.9
CNG fuel use rates are based on preliminary data analysis
34
CNG Fuel Use Rates for Average Cycle
Front-loader
Truck
FLC-1
FLC-2
FLC-3
Fuel
g/s mi/DGE
3.5
2.3
3.5
2.3
3.5
2.3
Max/Min:
1.0
Side-loader
Truck
SLC-1
SLC-2
SLC-3
Fuel
g/s mi/DGE
2.8
1.6
3.3
1.4
2.6
1.8
Max/Min:
CNG fuel use rates are based on preliminary data analysis
1.3
35
Exploratory Analysis: Diesel Fuel Use, SL-1
36
Exploratory Analysis: Diesel NOx Rates, SL-1
37
Conclusions for Duty Cycles
 Refuse truck duty cycles vary with configuration and
are different from cycles used in previous studies.
 EPA’s MOVES model should include at least one
refuse truck duty cycle.
38
Conclusions for Fuel Use Rates
 A higher value for fuel economy must be considered
for roll-off configurations.
 On average, compared to diesel, CNG trucks have
lower fuel economy.
 Overall fuel economy is not adversely affected by
emissions controls; the adverse effect (if any) of only
the emissions control device is offset by other
efficiency measures.
39
Acknowledgements
This work is sponsored by the Environmental Research
and Education Foundation (EREF).
Waste Industries (WI) provided refuse trucks for
measurement at their Garner and Durham facilities in
North Carolina, with extensive support from
management staff, technical staff, and drivers.
40
Questions Invited
Gurdas S. Sandhu
gssandhu@ncsu.edu
41
ADDITIONAL MATERIAL
42
MOVES STP References
 Development of Emission Rates for Heavy-Duty
Vehicles in the Motor Vehicle Emissions Simulator
MOVES2010. US EPA; 420-B-12-049; August 2012.
 Development of Emission Rates for Light-Duty
Vehicles in the Motor Vehicle Emissions Simulator
(MOVES2010). US EPA; 420-R-11-011; August 2011.
 MOVES2010 Highway Vehicle: Population and Activity
Data. US EPA; 420-R-10-026; November 2010.