2003 2003 - - 08 08 - - 26 26 CNG and diesel buses CNG and diesel buses 1 1 Summary of Swedish Experiences on CNG and ”Clean” Diesel Buses DEER 2003, August 24-28 Peter Ahlvik, Ecotraffic ERD 3 AB
20032003--0808--2626 CNG and diesel busesCNG and diesel buses 11
Summary of Swedish Experiences on CNG and ”Clean” Diesel Buses
DEER 2003, August 24-28
Peter Ahlvik, Ecotraffic ERD3 AB
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Acknowledgements
Pär Gustafsson and Olle Hådell, the Swedish National Road AdministrationMats Wallin and Charlotta Sandström, AVL MTC in SwedenJohn Fairbanks, DOE
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Outline
Introduction– Swedish auto ind.– Background
Regulations and incentives– SLTF vs. US & EU– Current bus fleet
Methodology– Data collection– Engine &
aftertreatment– Driving cycles
Results– NOX emissions – PM emissions– Formaldehyde– Benzene– 1,3-Butadiene– PAH– Cancer risk
DiscussionSummary & conclusions
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Swedish automotive industry today
Annual production of heavy-duty vehicles >16 tons
119
337
115
571
61 1
26
45 1
96
43 4
65
33 6
76
23 8
99
11 5
21
020 00040 00060 00080 000
100 000120 000140 000
Volvo DCPacca
rMAN
ScaniaIveco
Navistar
HinoAnn
ual p
rodu
ctio
n (#
/yea
r)
Source: BIL Sweden
owned by
owned by
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Background
First large fleet of ethanol buses in 1989 (Stockholm)Introduction of ultra-low sulfur diesel fuel in 1990 & “low-emission” diesel (i.e. ~Euro II) with ox catCNG buses in 1992 (Gothenburg); later also biogasRetrofit particulate filters (i.e. CRTTM) in mid 1990’sEnvironmental zones in larger cities (PM, HC and in 2nd
stage also NOX), 1996 (1st stage), 2002 (2nd stage)Retrofit EGR system with particulate filter in 1998Purchase recommendations by The Swedish Public Transport Association (SLTF) for bus fleets in 2001. Three levels for NOX and PM: base, rural and city.
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NOX regulations for HD busengines in EU and USA vs. SLTF
0
1
2
3
4
5
6
7
8
9
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
NO
X e
mis
sion
s (g/
kWh)
EUUSASLTF City
Driving cycles:Driving cycles:
USA: US TransientUSA: US TransientEU: ETC & ECE R49EU: ETC & ECE R49
--87 %87 %
0,270,27
2,02,02,32,3
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PM regulations for HD busengines in EU and USA vs. SLTF
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
PM e
miss
ions
(g/k
Wh)
EUUSASLTF City
Driving cycles:Driving cycles:
USA: US TransientUSA: US TransientEU: ETC & ECE R49EU: ETC & ECE R49
--55 %55 %
0,0130,013
0,0250,0250,020
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Current fleet of transit buses inSweden (Sept. 2001); total 7789
3032
1 772
2 138
135362 248
92 0 100
500
1 000
1 500
2 000
2 500
3 000
3 500
Uncontr.Ox cat DPF
DPF & EGR
EtOH, ox cat
CNG, ox cat
CBG, ox cat EEV HEV
# of
bus
es
Alternative fuels and otherDiesel
Source: SLTF
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Methodology
Collection of data on emissions, fuel production, etc. Baseline: Diesel Euro II engine, Swedish EC1 fuelDiesel aftertreatment: catalyst, DPF and DPF+EGR. Corrections for catalyst and DPF aging (diesel) Methane engine: SI (Otto), lean-burn w/, catalyst. Swedish results are grouped (average & BAT)Test cycles: Swe: Braunschweig, US: CBD, CSHVC. Corrections applied (CO2, diesel) for US tests.Comparisons of some selected emission results: Swe vs. US. Comparisons of cancer risk estimations.
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Options to reduce the exhaustemissions from in-use diesel engines
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The DNOx(TM) system from STTA retrofit and OEM EGR system
EGR valveEGR valve
PM filterPM filter
EGR cooler EGR cooler (hidden)(hidden) Control Control
unit (ECU)unit (ECU)
EGR pipeEGR pipe
Photo courtesy of STT Emtec
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Engine technology forheavy-duty CNG engines
TWC Lean-burn DFNG
PING DING (PI) DING (GP)
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Test cycles for transit buses
0
20
40
60
80
0 300 600 900 1200 1500 1800Time (s)
Spee
d (k
m/h
)
0
3
6
9
12
Dis
tanc
e (k
m)
SpeedDistanceBraunschweig cycle
0
20
40
60
80
0 300 600Time (s)
Spee
d (k
m/h
)
0
3
6
9
12
Dis
tanc
e (k
m)
SpeedDistance
CBD cycle
0
20
40
60
80
0 300 600 900 1200 1500 1800Time (s)
Spee
d (k
m/h
)
0
3
6
9
12
Dis
tanc
e (k
m)
SpeedDistanceCSHVC cycle
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NOX emissions (g/km)
10,7
14,8
9,8
13,7
10,6
7,02
5,61
13,814,2
10,311,3
5,46
7,076,316,05
2,84
5,84
0
2
4
6
8
10
12
14
16
Swe_CD
BP_ECD1
SwRI_CDSwe_Cat
ARB_Cat
Swe_DPF
Swe_DPF+EGR
ARB_DPFBP_DPF
SwRI_LED
ARB_CNG-3
BP_CNG2
SwRI_CNG
Swe_Meth_avg
Swe_Meth_BAT
ARB_CNG-3
ARB_CNG-CW
NO
X e
miss
ions
(g/k
m)
CNG w/ catCNG w/oDiesel w/ DPFDiesel w/ catDiesel w/o
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
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Particulate emissions (g/km)
0,20
0,150,13
0,054
0,17
0,0070,017
0,0030,0060,020
0,036
0,0020,013 0,0090,0090,0150,015
0,00
0,05
0,10
0,15
0,20
0,25
Swe_CD
BP_ECD1
SwRI_CDSwe_Cat
ARB_Cat
Swe_DPF
Swe_DPF+EGR
ARB_DPFBP_DPF
SwRI_LED
ARB_CNG-3
BP_CNG2
SwRI_CNG
Swe_Meth_avg
Swe_Meth_BAT
ARB_CNG-3
ARB_CNG-CW
Part
icul
ate
emiss
ions
(g/k
m)
CNG w/ catCNG w/oDiesel w/ DPFDiesel w/ catDiesel w/o
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
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Formaldehyde emissions (mg/km)
29,0
18,8
7,3
0
14,5
3,60,10,2
2,92,9
391 258 348
25,8
17,5
7,3
14,7
0
5
10
15
20
25
30
35
40
45
50
Swe_CD
SwRI_CD
ARB_Cat
Swe_DPF+EGRBP_DPF
ARB_CNG-3
SwRI_CNG
Swe_Meth_BAT
ARB_CNG-CW
Form
alde
hyde
em
issi
ons (
mg/
km) CNG w/ cat
CNG w/oDiesel w/ DPFDiesel w/ catDiesel w/o
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
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Benzene emissions (mg/km)
0
3,27
0,57
2,00
1,18
0,60
0,080,27
0,600,60
2,99
0,67
1,02
0,59
0,27
0,60
1,20
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
Swe_CD
SwRI_CD
ARB_Cat
Swe_DPF+EGRBP_DPF
ARB_CNG-3
SwRI_CNG
Swe_Meth_BAT
ARB_CNG-CW
Ben
zene
em
issi
ons (
mg/
km)
CNG w/ catCNG w/oDiesel w/ DPFDiesel w/ catDiesel w/o
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
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1,3-Butadiene emissions (mg/km)
0,000,00
17,4
0,00
5,22
0,910,000,00
6,966,96
3,13
0,000,18 0,000,00
10,0
20,0
0
4
8
12
16
20
24
Swe_CD
BP_ECD1
SwRI_CD
Swe_Cat
ARB_Cat
Swe_DPF
Swe_DPF+EGR
ARB_DPF
BP_DPF
SwRI_LED
ARB_CNG-3
BP_CNG2
SwRI_CNG
Swe_Meth_avg
Swe_Meth_BAT
ARB_CNG-3
ARB_CNG-CW
1,3-
But
adie
ne e
mis
sion
s (m
g/km
) CNG w/ catCNG w/oDiesel w/ DPFDiesel w/ catDiesel w/o
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
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12 species of tri+ PAH emissionsfor some selected tests
4085
9,22181
139
595
232,4
379
0
100
200
300
400
500
600
700
EPEFE EC1w/o aft
w/ catw/ DPF CD
LEDCNG
CNGCBG
PAH
em
issi
ons
( µg/
km)
Tests at SwRITests at MTC
Diesel truck w/o Diesel buses CNG/CBG buses
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Cancer risk index (diesel=100)Base case (T&E URFs)
0
20
40
60
80
100
120
Diesel Diesel, cat
Diesel, DPF
Diesel, EGR+DPFMethane "av."
Methane "BAT"
Can
cer
risk
inde
x (d
iese
l = 1
00) PAC
AldehydesAlkenesBenzeneParticulates
Unit risk factors (URFs) byTörnqvist & Ehrenberg
CNGDiesel Euro II
100100
6262
1717 1717
2727
4747
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Cancer risk index (diesel=100)URFs by US EPA 1990
0
20
40
60
80
100
120
Diesel Diesel, cat
Diesel, DPF
Diesel, EGR+DPFMethane "av."
Methane "BAT"
Can
cer
risk
inde
x (d
iese
l = 1
00) PAC
AldehydesAlkenesBenzeneParticulates
URFs by US EPA 1990
Alternative fuelsDiesel Euro II
100100
6969
1818 17172222
3838
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Cancer risk index (diesel=100)URFs by OEHHA, case #1
0
20
40
60
80
100
120
Diesel Diesel, cat
Diesel, DPF
Diesel, EGR+DPFMethane "av."
Methane "BAT"
Can
cer
risk
inde
x (d
iese
l = 1
00) PAC
AldehydesAlkenesBenzeneParticulates
URFs by OEHHA, but* PM only for diesel* Alt. fuels w/o PM
Alternative fuelsDiesel Euro II
100100
8585
1010 8,38,33,13,16,16,1
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Cancer risk index, four chemicalspecies only (URFs by OEHHA)
0
10
20
30
40
50
60
70
80
90
100
110
Swe_CD
BP_ECD1
SwRI_CD
Swe_Cat
ARB_Cat
Swe_DPF
Swe_DPF+EGR
ARB_DPF
BP_DPF
SwRI_LED
ARB_CNG-3
BP_CNG2
SwRI_CNG
Swe_Meth_avg
Swe_Meth_BAT
ARB_CNG-3
ARB_CNG-CW
Can
cer
risk
inde
x (d
iese
l=10
0)
AcetaldehydeFormaldehyde1,3-ButadieneBenzene
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
100
2,06,9
31,737,8
1,1
37,8
0,3 0,15,6
76,1
84,8
48,9
108,8
54,4
4,7 6,0
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Cancer risk index, four chemicalspecies and PM (URFs by OEHHA)
0
10
20
30
40
50
60
70
80
90
100
110
Swe_CD
BP_ECD1
SwRI_CD
Swe_Cat
ARB_Cat
Swe_DPF
Swe_DPF+EGR
ARB_DPF
BP_DPF
SwRI_LED
ARB_CNG-3
BP_CNG2
SwRI_CNG
Swe_Meth_avg
Swe_Meth_BAT
ARB_CNG-3
ARB_CNG-CW
Can
cer
risk
inde
x (d
iese
l=10
0)
AcetaldehydeFormaldehyde1,3-ButadieneBenzeneParticulates
Diesel w/o Diesel w/ cat Diesel w/ DPF CNG w/ catCNG w/o
100
69,661,1
82,3
11,4
25,7
9,93,1 1,3 3,6
9,9
21,5
3,4
12,7 9,94,6 4,8
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Conclusions 1(2)
Regulations and incentives are importantTransit buses in larger cities use ULSD and DPF/DPF+EGR or alt. fuels with ox. catalystNOX is fairly similar for US & Swe. CNG has lower NOX than diesel but is matched by EGR. NOX affected by driving cycle “optimization”?PM is generally higher for Euro II than US -98. CNG and diesel with DPF are roughly similar.Very high formaldehyde level for CNG w/o cat. No Swedish results for CNG w/o catalyst (!!!)
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Conclusions 2(2)
Benzene is fairly low for both fuels; impact of cat1,3-Butadiene results are inconsistentURFs has considerable impact on cancer riskFormaldehyde and 1,3-butadiene most important chemical species with OEHHA URFsPM is of great importance with OEHHA URFs. What is the impact of PM from alternative fuels?Importance of PAH (PAC)?The emission technology applied may be of greater importance than the fuel choice
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This concludes my presentation
Thank you for your attention!Questions?
More information available at: www.ecotraffic.se
www.vv.se(e.g. reports, presentations, etc.)