CarEcology:
New Technological and Ecological Standards
in Automotive Engineering
Green Fuels
The use of the gas fuels CNG, LNG and LPG
as alternative automotive fuels
Merkouris Gogos
Technological Educational Institute of Thessaloniki
Department of Vehicles
Antwerp, October 2009
Alternative fuels
 The term “alternative fuel” is used to describe any fuel
suggested for use in transportation vehicles other than
petrol or Diesel fuel.
 The EU has set the objective of a 10% substitution of
traditional fuels in the road transport sector by
alternative fuels before the year 2020.
 Alternative fuels include biofuels (eg. bioethanol,
biogas, biodiesel), natural gas, hydrogen, methanol,
liquefied petroleum gas (LPG) and gas-to-liquids (GTL).
 Not to be confused with renewable sources or biofuels.
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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2
R.Hefner III
Consumption of Solid, Liquid and Gas Fuels
Actual and projected consumption of fuels
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Gas Fuels
Three alternative gas fuels will be discussed in this lecture:
Compressed Natural Gas (CNG)
Liquefied Natural Gas (LNG)
Liquefied Petroleum Gas (LPG)
Although not green, these fuels are certainly greener than
traditional Diesel or petrol.
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4
History of Gas fuelled vehicles: The early days
World War I
A bus powered by
coal gas on
Waverley Bridge,
Edinburgh, during
World War I
Petrol shortage
compelled this wartime improvisation a 'gas-bag' omnibus
with Lothian chassis
operated by Scottish
Motor Traction
Company, 1914-18
www.edinphoto.org.uk
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History of Gas fuelled vehicles: The early days
Early Natural Gas Vehicles used low
pressure natural gas stored in
bladders
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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NREL/CD-540-37146
Circa 1930
6
History of Gas fuelled vehicles: The early days
Tempi s.p.a.
Bottom: in September 1936, this
Alfa Romeo 350 bus, fuelled by methane gas,
won the Italian National race in five stages
Tempi s.p.a.
Top: This Citroën bus was the first one
modified by the “Alberto Laviosa” workshop of
Piacenza, Italy to run on methane gas.
In 1935, it was test-driven on the line
“Piacenza - Rivergaro”.
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History of Gas fuelled vehicles: WW II
blog.modernmechanix.com
Popular Science (April, 1940)
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History of Gas fuelled vehicles: WW II
Traction avant
Citroën
fonctionnant au
gaz de ville*,
Paris,
Octobre 1941
© LAPI / Roger-Violle
*Town Gas:
mixture of
H2, CO, CH4
and impurities
(CO2, N2 and
other)
About half the
energy content
of methane.
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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History of Gas fuelled vehicles: WW II
The energy shortages
during World War II
made NGVs popular in
Europe.
Advancements in
compressor technology
allowed the use of higher
pressure steel cylinders
on the roof of this
Citroën sedan.
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Le Gazogène
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Alternative Gas Fuels
Today the alternative gas fuelled engines can be modified
or retrofitted engines that were originally designed for petrol
or Diesel fuelling. They are, therefore not the optimum
design for the other fuels.
However, various operational requirements for retrofitted
engines need to be taken into account:
 The different combustion characteristics of alternative
fuels require a change in the injection and ignition timing.
 Many alternative fuels, especially those in gaseous form,
have low lubrication, causing increased wear of fuel
components such as fuel injectors and valves.
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Energy consumption in road transportation
LPG 1.5%
CNG 0.2%
European Communities, 2008
(2005 shares)
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Natural Gas
Natural gas is found
underground where it was
formed millions of years ago
from organic matter.
Tremendous pressure from the overlying rock, combined
with the earth's heat, converted the matter into a gaseous
fossil fuel trapped under layers of solid rock.
It is an organic compound made up of hydrogen and
carbon and is usually referred to as a hydrocarbon.
It is often produced in association with production of crude
oil. However, wells are also drilled for the express purpose
of producing natural gas.
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Fuel prices in Europe
(1/2)
Country
Armenia
Austria
Belarus
Belgium
Bosnia-Herzegovina
Bulgaria
Croatia
Czech Republic
Finland
France
Germany
Iceland
Italy
Latvia
Liechtenstein
Premium
Petrol
(€/litre)
0.79
1.06
0.69
1.28
0.81
0.92
0.84
1.24
1.46
1.48
1.42
1.47
1.48
1.08
Regular
Petrol
(€/litre)
0.73
1.05
0.55
1.26
0.64
0.86
0.83
1.42
1.37
1.22
1.39
1.39
0.79
1.01
Diesel
(€/litre)
CNG
(€/Nm³)
0.71
1.04
0.55
0.99
0.74
0.87
0.86
1.28
1.20
1.15
1.33
1.41
1.34
0.82
1.10
0.27
0.89
0.27
0.61
0.25
0.55
0.33
0.64
0.78
0.64
0.70
0.90
0.68
0.23
0.53
CNG price
per litre
petrol
0.24
0.80
0.24
0.55
0.22
0.52
0.30
0.57
0.70
0.57
0.54
0.81
0.64
0.21
0.46
CNG price
per litre
Diesel
0.28
0.91
0.28
0.63
0.26
0.59
0.34
0.66
0.80
0.66
0.72
0.92
0.71
0.24
0.50
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Gas Vehicles Report, Sep 2009
Data updates Dec 2008 - July 2009
15
Fuel prices in Europe
(2/2)
Country
Lithuania
Luxembourg
Moldova
Netherlands
Norway
Poland
Portugal
Russia
Serbia
Slovakia
Spain
Sweden
Switzerland
Turkey
United Kingdom
Premium
Petrol
(€/litre)
1.09
1.08
1.35
1.48
1.08
1.13
0.80
0.94
1.02
0.97
0.95
1.70
1.04
Regular
Petrol
(€/litre)
1.07
1.06
0.50
1.28
1.43
1.15
1.07
0.69
1.01
0.87
1.01
0.92
1.60
1.00
Diesel
(€/litre)
CNG
(€/Nm³)
0.97
0.87
0.43
0.99
1.32
0.91
1.01
0.70
0.84
1.06
0.90
1.02
1.09
1.26
1.16
0.65
0.53
0.18
0.53
0.46
0.51
0.55
0.22
0.66
0.76
0.57
1.01
0.86
0.78
0.71
CNG price
per litre
petrol
0.58
0.47
0.16
0.47
0.41
0.46
0.49
0.20
0.59
0.68
0.44
0.80
0.75
0.68
0.63
CNG price
per litre
Diesel
0.67
0.54
0.18
0.54
0.47
0.52
0.56
0.23
0.68
0.78
0.49
0.90
0.82
0.76
0.73
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Gas Vehicles Report, Sep 2009
Data updates Dec 2008 - July 2009
16
Transportation of Natural Gas
 Pipelines are convenient and economical for onshore
transport of natural gas.
 Offshore, as the water depth and distance increase,
pipeline transport of gas becomes difficult.
 LNG for offshore transport of gas.
 LNG is liquid at -162 °C and atmospheric pressure,
transported in specially designed ships.
 40% of the trade movement of natural gas in 2008 was
as LNG (BP Statistical Review, 2009).
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LNG Tanker
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Projected routes of natural gas pipelines
NORTH STREAM:
Russia - EU (via Baltic sea)
Capacity: 55 billion m3/year
Scheduled for operation:
First line:2011
Second line: 2012
SOUTH STREAM:
Russia - EU (via Black sea)
Capacity: 63 billion m3/year
Scheduled for operation:
End of 2015
NABUCCO:
Caspian region - EU
Capacity: 31 billion m3/year
Scheduled for operation:
End of 2015
www.energy.eu
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Pipeline Natural Gas composition
Methane
85 - 95%
Ethane
Propane
Pentane
Hexane
Other
NREL/CD-540-37146
Butane
In the ground, natural gas contains a wide range of compounds. During well-head
cleaning and processing, gas quality is improved to pipeline standards. Gas in the
pipeline has a range of acceptable compositions. Typical pipeline gas would be as
shown.
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Natural Gas Properties
 Main component is methane CH4
 Lighter than air (specific gravity 0.55 to 0.65)
 Tasteless and odourless. Odorant is added for safety
 Non-toxic
 Simple asphyxiant gas (ie. displaces oxygen from the air)
 Flammable in concentrations of 5% to 15% by volume in air
 Not a liquid when compressed (it just becomes very dense)
 Boiling point -162 ºC. Above this temperature it is gaseous
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Advantages of Natural Gas
(1/2)
 Nearly zero sulphur level and, thus, negligible sulphate
emissions
 Very low particulate emissions because of low carbon-tohydrogen ratio
 Due to its low carbon-to-hydrogen ratio, it produces less
carbon dioxide than either gasoline or diesel
 Low cold start emissions due to its gaseous state
 Superior anti-knock properties due to its very high Octane
number, thus allowing higher compression ratios and
operation under turbocharged conditions
 Very low summer smog potential
 Negligible evaporative emissions
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Advantages of Natural Gas
(2/2)
 Lower adiabatic flame temperature than conventional fuels,
leading to lower NOx emissions
 Higher calorific value than petrol on a mass basis
 Much higher ignition temperature than petrol and diesel,
making it more difficult to auto-ignite, thus it is safer
 Does not contain toxic components
 Much lighter than air and thus it is safer
 Methane is not a volatile organic compound (VOC)
 Engines fuelled with natural gas in heavy-duty vehicles offer
more quiet operation than equivalent diesel engines, making
them more suitable for use in urban areas
 Stable combustion at leaner mixtures due to its extended
flammability limits
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Disadvantages of Natural Gas
(1/2)
 Transportation of natural gas on board a vehicle is
complicated; it can be stored as compressed gas at 200 bar
or as a liquid at -162°C and 2-6 bar pressure
 It requires dedicated catalysts with high loading of active
catalytic components to maximise methane oxidation
 Its composition varies widely between countries and
between cities, depending on the gas origin, which affects
the stoichiometric air/fuel ratio
 Limited driving range because its energy content per unit
volume is relatively low as a result of its gaseous state
 The energy required for the compression of natural gas
leads to 4% more CO2 emitted by the car
 It requires special refuelling stations
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Disadvantages of Natural Gas
(2/2)
 Longer refuelling time than petrol or diesel
 Increased consumption due to a heavier fuel tank
 Lower burning rate compared to petrol due to lower laminar
flame speed
 Injection of natural gas into the port at low pressure and
directly into the cylinder at high pressure requires modified
and special injectors, respectively
 Exhaust emissions of methane (GHG) are relatively high
 Absorbs water vapour which may freeze under certain
conditions; thus its maximum water content should be limited
 Approx. 10% lower power output than equivalent petrol–
fuelled vehicles
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Worldwide NGVs
Data updates Dec 2008 - July 2009
Cars/LDVs
40
MD/HD
Trucks
% of total
Others NGVs in
the world
1
Pakistan
???
2 191 000
2 140 960
50 000
20.84%
2
Argentina
1 786 989
1 786 989
17.00%
3
Brazil
1 605 041
1 605 041
15.27%
4
Iran
1 537 790
1 532 268
5 522
5
India
700 000
315 200
12 000
715
6
Italy
523 100
519 600
2 300
1 200
7
China
400 000
231 685
112 755
1 100
54 460
3.80%
8
Colombia
294 615
179 332
13 800
9 660
91 823
2.80%
9
Bangladesh
180 000
117 229
3 233
8 355
51 183
1.71%
10
Thailand
147 265
119 888
10.195
15 509
1 673
1.40%
11
Ukraine
120 000
7 000
30 500
29 500
53 000
1.14%
12
Bolivia
116 292
116 292
14.63%
372.085
6.66%
4.98%
1.11%
91.34%
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Gas Vehicles Report, Oct 2009
Total
MD/HD
Buses
26
Worldwide Natural Gas fuelling stations
Data updates Dec 2008 - July 2009
Public
Private
Planned
1
Pakistan
2 941
2 941
18.47%
2
Argentina
1 826
1 826
11.47%
3
Brazil
1 746
1 746
10.97%
4
China
1 336
920
416
230
8.39%
5
Iran
928
867
61
638
5.83%
6
Italy
700
630
70
80
4.40%
7
India
500
181
319
8
Colombia
458
458
2.88%
9
Bangladesh
425
425
2.67%
10
Thailand
331
306
25
11
Ukraine
224
204
20
12
Bolivia
128
128
3.14%
72
2.08%
1.41%
0.80%
72.5%
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Gas Vehicles Report, Oct 2009
Total
% of total
fuelling stations
in the world
27
CSE New Delhi, 2001
CNG powered 3-wheelers in India
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CNG powered 3-wheeler
Rozgar 4-Stroke CNG 200 cc Water Cooled Engine from Pakistan
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The long-term
objective of this EUproject is to promote
the realisation of a
network of filling
stations for biogas
and natural gas
reaching from the
northernmost tip of
Europe, Finland, to
the south of Italy, in
other words: the
GasHighWay.
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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NGVA Europe, 2009
The GasHighWay
30
Fuel Property
Formula
Molecular weight
Composition (% w/w)
Carbon
Hydrogen
Oxygen
Density (kg/L) (gases at boiling point)
Freezing Point (°C)
Boiling Point (°C)
Autoignition temperature (°C)
Latent Heat of Vaporisation (kJ/kg)
Lower Heating Value (MJ/kg)
Flammability limits (%v/v)
Stoichiometric Air-Fuel Ratio
Octane Number (RON)
Octane Number (MON)
Cetane Number
Methane
Petrol
Diesel
CH4
16
C4 to C12
100-105
C8 to C25
~200
75
25
0
0.42
-182
-162
540
510
50
5-15
17.2
120 est.
120 est.
-
85-88
12-15
0-4
0.69-0.79
-40
27-225
~ 257
349
41-43
1.4-7.6
14.7
88-100
80-90
-
84-87
13-16
0
0.81-0.89
-40 to -1
188-343
~ 316
233
42-44
1.0-6.0
14.7
40-55
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Bechtold, 1997
Methane properties
31
Energy Density: Natural Gas vs. Diesel
Diesel
10 kWh/L
Natural Gas
10 Wh/L
1 m3
1 bar
20oC
1
1000
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CNG Volume vs. Diesel Volume
CNG
200 bar
200 bar
Diesel
200 bar
200 bar
200 bar
1
5
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LNG Volume vs. Diesel Volume
Diesel
LNG -162 °C
 = 0.83 kg/L
 = 0.35 kg/L
1
2
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CNG vs. LNG Comparison
CNG
LNG
Physical state
Gas
Liquid
Temperature in vehicle tank
Ambient
-162 °C
Typical pressures in tank
200 or 250 bar
5-8 bar
Density
175 kg/m3 @200bar
435 kg/m3
Energy content
27% petrol eq. @ 200bar
33% petrol eq. @ 2 50bar
67% petrol eq.
Typical usage
Cars/Busses
Trucks
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Volume
(gal)
Weight
incl. fuel
(lb)
Energy
(103 BTU)
Tank
Cost
($ 1993)
Range
(mi)
Petrol
12.4
87
1415
25
332
CNG
Steel/Comp
39.6
332
1420
1545
333
CNG
Alum/Comp
40.3
293
1435
1695
337
CNG
All Comp
39.6
143
1415
2050
332
LNG
18.0
157
1435
1875
337
Fuel storage
system
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Ingersoll, 1996
Fuel storage on-board a vehicle
36
Fuel storage: Natural Gas vs. Petrol
Volume
Weight
incl. fuel
Tank Cost
1
1
1
CNG Steel/Composite
3.2
3.8
62
CNG Alum/Composite
3.3
3.4
68
CNG All Composite
3.2
1.6
82
LNG
1.5
1.8
75
Fuel storage system
Petrol
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Catalyst conversion efficiency vs. temperature
Conversion
Efficiency
(%)
100
Propane
Propylene C H Butane
3 8
C4H10
C3H6
Ethane
C2H6
Ethylene
C2H4
80
60
40
Methane
CH4
20
0
100
200
300
400
500
Catalyst Temperature (oC)
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Natural Gas Vehicles
 Dedicated vehicles
Dedicated vehicles are run on natural gas only.
 Bi-Fuel vehicles
Bi-Fuel vehicles operate on CNG while retaining the ability to use
petrol as a reserve fuel. The engine can operate on either fuel but
not on both simultaneously. The compression ratio of the engine
must remain at a level suitable for petrol. Currently this type of
engine is used almost exclusively on vehicles below 3500 kg.
 Dual Fuel vehicles
Dual Fuel engines are derived from diesel engines. A small
amount of diesel is retained as a pilot source of ignition. The
primary fuel, Natural Gas, is mixed with the incoming air as the
bulk fuel. Dual Fuel engines are auto ignited by compression and
require no spark plugs.
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Compressed Natural Gas
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Schematic diagram of a 6 Cylinder MPI system
Gas Injectors
Pressure
Regulator
Gas supply
(200 bar)
Injector Supply Manifold (Rail)
Coils
Spark Plugs
Electronic
Control Unit
Lambda
Probe
Engine
Speed
Sensor
Phase Water Temp Air Temp
Sensor
Sensor
Sensor
Air Flow
Sensor
Throttle
Position
Sensor
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Components for natural-gas operation
Bosch, 2007
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Cylinder Properties
Four Cylinder Types:
 Type 1: All metal made of steel with no covering, other than
paint. This is the most common type of cylinder.
 Type 2: Metal cylinder (steel or aluminium) with a partial
wrapping made of glass or carbon, contained in an epoxy or
polyester resin.
 Type 3: Cylinder fully wrapped most often with carbon fibre. This
type has a metal liner (usually aluminium).
 Type 4: All-composite (non-metallic). Cylinder is fully wrapped
with 100% carbon fibre and a plastic or carbon fibre liner.
As a safety factor, all tanks are over-designed in order to withstand a
pressure more than 2.5 times the operational pressure.
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Fiat Marketing, 2007
Fiat Panda 1.2 CNG tanks
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Opel Zafira 1.6 CNG
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www.cng.cz
Opel factory
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46
CNG powered urban busses
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47
City
Total number of
busses
Natural Gas
busses
% of Natural Gas
busses
Berlin
1700
10
0.60%
Paris
4000
53
1.30%
Rome
2383
40
1.70%
Madrid
1000
15
1.50%
Athens
2039
416
20.40%
New York
5675
358
6.30%
Los Angeles
2638
795
30.10%
Toronto
1500
125
8.30%
Vancouver
1006
51
5.10%
Sydney
3900
254
6.50%
850
52
6.10%
Beijing
10000
1640
16.40%
Delhi
12000
6175
51.50%
Perth
CarEcology: New Technological and Ecological Standards in Automotive Engineering
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Sgourakis, 2008
CNG powered urban busses
48
Natural Gas filling station in Athens
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49
The Economic Commission for Europe (ECE) has introduced
Regulation No. 110 to provide uniform provisions concerning:
I. Approval of specific components of motor vehicles using CNG in
their propulsion system;
II. Approval of vehicles with regard to the installation of specific
components of an approved type for the use of CNG in their
propulsion system.
To prevent bursting of a CNG cylinder during accidents involving
fires, automotive CNG cylinders have to be equipped with a
Pressure Relief Device (PRD). The effectiveness of the specified
fire protection system has to be tested in a Bonfire as defined in
annex 3 (article 5.3.5 and appendix A.15) of ECE Regulation No.
110 (E/ECE/TRANS/505).
TNO, 2008
ECE Regulation No.110 (E/ECE/TRANS/505)
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TNO, 2008
Bonfire test CNG automotive cylinder
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51
Auto Fire with CNG Fuel Tank Explosion
(1/6)
Seattle Fire Department
Incident #26564, March 26, 2007
 Dispatch 0230 hours for car fire (Engine 10)
 E10 arrived and requested FIB for multiple vehicles
with possible structural exposures (freeway columns
and overpasses)
 12 vehicles damaged or destroyed
 Firefighter near miss when CNG vehicle exploded as
E10 crew approached with a handline (approximately
15-20 m away)
 Determined to be arson
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Auto Fire with CNG Fuel Tank Explosion
(2/6)
Debris from the explosion was thrown up to 30 m in all directions
including on the over-passes above the incident
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Auto Fire with CNG Fuel Tank Explosion
(3/6)
Roof is blown
completely
off vehicle
and doors
blown open
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Auto Fire with CNG Fuel Tank Explosion
(4/6)
Roof debris
+
+
+
+
Bumper frame
Trunk lid
Backhoe
Fuel tank
Roof debris
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Auto Fire with CNG Fuel Tank Explosion
(5/6)
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Auto Fire with CNG Fuel Tank Explosion
(6/6)
Evidence
indicates that
the fuel tank
may have
ricocheted off
the underside
of a freeway
overpass
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CNG Filling
Two categories:
 Fast fill (3-5 min)
In a fast fill station pressurized fuel is stored in tanks
that are continually refilled by compressors. Multiple
tanks may be configured in a cascading arrangement,
in which tanks come into service as needed.
 Slow fill (overnight)
In a slow fill facility vehicles are filled directly from the
compressor. Such equipment, which includes
compressors but no storage tanks, typically serves
small fleets.
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CNG Fast Fill
3
4
1
2
5
6
1. Gas grid
2. Gas dryer
3. Gas compressor
4. Priority panel
5. Storage cylinders (cascade)
6. Dispenser
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Fast Fill cascade installation
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Fast Fill Nozzles
(1/2)
OFF
ON
When the handle is
rotated 180º to the
“on” position, an
arrow visible from
the top, points
toward vehicle
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Fast Fill Nozzles
(2/2)
OFF
ON
OFF
ON
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CNG Slow Fill (Fleet filling)
2
3
1
1. Gas grid
2. Compressor station
3. Buffer
4. Dispensing posts
5. Connectors
4
5
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CNG Slow Fill (Fleet filling)
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Slow Fill Nozzles
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CNG Slow Fill (Home filling)
1
2
3
4
1. Gas grid
2. Gas metre
3. Home refuelling appliance
4. Connector
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CNG Residential Refuelling
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Liquefied Natural Gas
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LNG
Although natural gas is a gas at normal temperatures and
pressures, it becomes a liquid when it is cooled to -162°C
(LNG cannot be converted to a liquid by pressure alone),
at which point the gas condenses into a liquid.
Liquefaction removes oxygen, carbon dioxide, sulphur
compounds, and water. By liquefying natural gas, it is
possible to reduce the bulk or volume of the gas by about
a factor of 600 which facilitates its transport by ship and
tanker lorries. It can be turned back into a gas and
delivered into domestic gas pipelines.
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LNG on board storage
The LNG fuel tank is a cryogenic container that is
designed as two separate pressure vessels, one inside
the other.
The inner vessel stores the cold LNG in its liquid form
and is wrapped with multiple layers of non-combustible
insulation and reflective foil. It is then sealed within the
outer vessel.
The space between the inner and outer vessels is then
evacuated to produce a superior insulation system.
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LNG: Safety first
A LNG vehicle parked indoors and unmoved for a week
or more will vent a flammable gas mixture that could
catch fire in the vicinity of an ignition source.
To address this safety issue, LNG use should be
restricted to frequently driven fleet vehicles or to vehicles
stored outdoors. Only trained personnel should service
the vehicles.
EPA420-F-00-038, March 2002, www.epa.gov
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Dual-Fuel Fundamentals
 A Dual-Fuel engine is a diesel engine – no basic
change
 Dual-Fuel uses a diesel pilot injection to ignite a lean,
homogeneous mixture of natural gas and air
 Retains diesel-cycle performance & efficiency with up
to 90% gas substitution
 Can use LNG or CNG
 Delivers lower regulated & carbon emissions than
diesel
 Returns to 100% diesel operation automatically and
instantaneously when gas supply is terminated
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Clean Air Power, 2008
LNG Trucks
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Clean Air Power, 2008
LNG Tanks
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LNG Filling station
Storage
Vessel
5.5 - 7 bar
Offload
Connectors
Vaporiser
LNG
Dispenser
LNG
Cryogenic pump
NexGen Fuelling
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LNG/LCNG filling station
World’s largest LNG/LCNG station built by Chart-NexGen in California.
4×60.000 litres storage capacity, 6 LNG dispensers and 3 LCNG dispensers.
Serving 200 refuse vehicles (www.chart-ferox.com)
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LCNG Filling station
CNG storage
Cascade system
CNG
Dispenser
Ambient
Vaporiser
Storage
vessel
Offload
Connectors
Odouriser
LCNG
Cryogenic pump
NexGen Fuelling
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Liquefied Petroleum Gas
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Liquefied Petroleum Gas
 LPG consists mainly of propane (C3H8) with
some butane (C4H10).
 The ratio of carbon to hydrogen is important;
the smaller the ratio of C to H, the better for the
environment. It follows that methane is a better
gas in this respect, but only if is fully burnt!
 It has been used as a vehicle fuel for at least
the past 70 years. Nearly all LPG vehicles are
conversions of petrol vehicles.
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Production of LPG
 About half of LPG is produced in association
with production of natural gas and the other
half is produced in association with crude oil
refining.
 Natural gas must be free of those gases that
would liquefy under the modest pressures
used in natural gas pipelines. Such gases are
the LP gases propane and butane.
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Use of LPG
The major use of LPG is for heating. It is also an
important feedstock for petrochemicals.
It can be used to power cars, buses and trucks,
however, it is not really suitable for vehicles
above 3.5 t gvw, as it does not provide the
required performance.
For various reasons, one of which being the fact
that alternative fuels are available, LPG is best
suited to light vehicles such as cars and small
vans which normally run on petrol.
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LPG Storage
LPG is liquefied by moderate compression at
normal temperatures (less than 20 bar) and is
stored in appropriate tanks and cylinders.
The liquefaction is necessary to provide a
reduction in volume and produce acceptable
energy densities. The main application discussed
here is as a fuel for motor vehicles.
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Fuel Property
Formula
Molecular weight
Composition (% w/w)
Carbon
Hydrogen
Oxygen
Density (kg/L) (gases at boiling point)
Freezing Point (°C)
Boiling Point (°C)
Autoignition temperature (°C)
Latent Heat of Vaporisation (kJ/kg)
Lower Heating Value (MJ/kg)
Flammability limits (%v/v)
Stoichiometric Air-Fuel Ratio
Octane Number (RON)
Octane Number (MON)
Cetane Number
Propane
Petrol
Diesel
C3H8
44.09
C4 to C12
100-105
C8 to C25
~200
82
18
0
0.58
-187
-42
457
426
46
2.1-9.5
15.7
112
97
-
85-88
12-15
0-4
0.69-0.79
-40
27-225
~ 257
349
41-43
1.4-7.6
14.7
88-100
80-90
-
84-87
13-16
0
0.81-0.89
-40 to -1
188-343
~ 316
233
42-44
1.0-6.0
14.7
40-55
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Bechtold, 1997
Propane properties
83
Benefits of using LPG
 The cost per litre is halved compared to petrol.
 LPG vehicles are eligible for grants (amongst
other low exhaust-polluters). e.g. LPG vehicles
can qualify for 100% exemption from the
London Congestion charge.
 Burning LPG results in less sulphur deposits
on the engine, while at the exhaust end fewer
HC and less CO are emitted.
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Disadvantages of LPG
 The extra volume taken up by the gas tank will
reduce the available load space.
 The vehicle manufacturer’s original guarantee
may be invalidated.
 The insurance premiums may be increased.
 Low number of fuel stations.
 About 5% less power than petrol
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Schematic diagram of an LPG system
Bosch, 2007
1. Gas shut-off valve
2. Evaporator pressure
regulator
3. Throttle device
4. Intake manifold
pressure sensor
5. Injector
6. Ignition coil with
spark plug
7. Lambda sensor
8. Control unit
9. Speed sensor
10. Temperature sensor
11. Primary catalytic
converter
12. Lambda sensor
13. CAN interface
14. Diagnosis lamp
15. Diagnosis interface
16. Ventilation line
17. LPG tank
18. Housing with tank
fittings
19. External filler valve
20. Main catalytic
converter
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LPG Sequential Injection Kit
LPG tank
Switch
Electronic
Control
Unit
Pressure
sensor
Multivalve
Injection Rail
BRC
LPG regulator
Emmegas
LPG filter
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LPG dispenser on a wharf at Constance lake
Emission values for new mid-sized vehicle registrations in the EU in 2002
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CNG and LNG incentives in Italy (2009)
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Price List 2008/09
For all engine
transformations
to LPG or CNG,
a price list for
the public has
been adopted
by all
workshops,
thereby
guaranteeing a
maximum
amount which
cannot be
overridden.
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LPG/CNG ECU Features
 Fully Functional OBDII
Keeps the original equipment manufacturer OBDII system completely
functional when operating on Petrol and also when operating on LPG or
Natural Gas. Does not intervene the OEM OBD trouble codes or malfunction
indication lights. The calibration of the Alternative Fuel system must be done
and verified using an OBD scanner.
 Automatic Change Over Fuels
Petrol to CNG/LPG or CNG/LPG to Petrol automatic change over. The
installer can define and adjust change parameters based on multiple
conditions considering fuel temperature, fuel pressure, RPM, etc.
 Calibration
The ECU can be calibrated manually at different engine loads during the
calibration process to achieve emission levels equal to the OEM.
 Real Engine Mapping
The ECU can capture real engine mapping while the engine run at different
power load on the road or on a dynamometer.
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Emissions
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Pollutant emissions: CO
0.8
CO (g/km)
0.6
0.4
0.2
0.0
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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Pollutant emissions: NMHC
NMHC (g/km)
0.100
0.075
0.050
0.025
0.000
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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Pollutant emissions: NOx
NOx (g/km)
0.8
0.6
0.4
0.2
0.0
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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Pollutant emissions: Particulates
Particulates (g/km)
0.045
0.030
0.015
0.000
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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Pollutant effects: Summer smog
Athens under photochemical smog
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Pollutant effects: Winter smog
Belgium, December 2007
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Pollutant effects: Acid Formation
20
mmol H
+
15
10
5
0
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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Pollutant effects: Acid Rain
Great Smoky Mountains National Park
Sacré-Cœur Gargoyle
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CO2 + 23 CH4 + 296 N2O (g/km)
Pollutant effects: Greenhouse gas
200
150
100
50
0
Petrol
LPG
CNG
Diesel
Emission values for new mid-sized vehicle registrations in the EU in 2002
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BioGAS (BioMethane)
 Biomethane is a renewable resource and does not compete with
food production.
 Methanisation is used for producing biogas from organic matter of
plant or animal origin.
 Biogas is rich in methane, which is also found in natural gas.
 Biogas can be collected directly in landfill waste disposal centres or
produced with the aid of digesters.
 All kinds of organic matter can be converted into biogas.
 Effluents can be methanised in waste treatment plants.
 Liquid manure, agricultural waste and energy crops can be
methanised in small biogas units on farms or in co-digestion units.
 Solid household waste and “green” waste can also be converted
into biogas in large plants for methanisation of solid waste.
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Hythane = Hydrogen + Methane
Hythane is a mixture of natural gas and hydrogen 5-7%
by energy.
Benefits include: Extended lean flammability limits,
increased flame speed, easier ignition and more efficient
catalysis.
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Thanks for your attention!
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