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Estimation of Greenhouse Gas Emissions Related to Urban Driving Patterns

Conference Paper

Estimation of Greenhouse Gas Emissions Related to Urban Driving Patterns

Abstract and Figures

Road transportation is one of the major sources of greenhouse gas pollution. In recent years there has been considerable development in vehicle technology to reduce fuel consumption and CO2 emissions of passenger cars, but at the same time number of vehicles per 1000 capita is increasing especially in developing countries. In this study, the effect of driving patterns on CO2 emissions has been investigated by testting a sample of thirty passenger cars according to three different driving cycles. Different emission reduction technologies are also investigated for the same fleet.
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Estimation of Greenhouse Gas Emissions Related to
Urban Driving Patterns
Metin ERGENEMAN, Cem SORUŞBAY
Istanbul Technical University, Mechanical Engineering Faculty, Automotive Laboratory, Maslak - Istanbul
Ali G. GÖKTAN
OTAM, I.T.U. Automotive Laboratory, Maslak - Istanbul
ABSTRACT
Road transportation is one of the major sources of greenhouse gas pollution. In recent years there has been
considerable development in vehicle technology to reduce fuel consumption and CO2 emissions of
passenger cars, but at the same time number of vehicles per 1000 capita is increasing especially in
developing countries. In this study, the effect of driving patterns on CO2 emissions has been investigated by
testting a sample of thirty passenger cars according to three different driving cycles. Different emission
reduction technologies are also investigated for the same fleet.
Key-words: Driving cycles, Greenhouse gas emissions, fuel consumption.
INTRODUCTION
Although the internal combustion engine is an old
and pollutant machine for the modern world, it still
holds its position in many applications against the
alternatives due to some economic and technical
advantages. The utilization of these machines is
most likely to continue for road, marine and some
aviational transportation systems in the near
future.
Road vehicles are powered today by internal
combustion engines of either spark ignition or
compression ignition. It is not expected that full
electric vehicles powered by batteries will be
capable to maintain the present vehicle range with
acceptable weight, dimension and cost within the
next twenty years, although some restricted
applications on small and medium class cars are
ready to come into market. Usage of the fuel cell
to produce electricity on board is expected to be
possible even later then twenty years time. Within
these systems the problem is the storage of
hydrogen, which seems to be the only possible
fuel to be used in fuel cell on board.
Electric vehicles have constrains such as high well
to wheel CO2 emissions along with the problems
introduced with on board battery or hydrogen
storage systems. A medium size car powered with
a small (1.4 to 1.6 litre) and turbocharged Diesel
engine has a fuel consumption of 6 liters/100 km
on average and produces 155 g-CO2/km. The CO2
production could be decreased to 95 g-CO2/km
(3,6 liters/100 km) within the next ten years by
reducing the vehicle mass and developments in
engine efficiency and application of hybrid
strategies.
CO2 production during electricity production is on
average 500-700 g-CO2/kWh depending on the
percentages of the primary energy sources (i.e.
Hydrocarbon fuels, coal, natural gas, hydraulic,
wind and nuclear energy) used. USA, uses 80%
coal to produce electricity with an emission factor
of 600 g-CO2/kWh, while France for example has
much lower average emission factor due to 75%
electricity production using nuclear energy.
Approximately 25% of the total energy production
of the world is consumed by the transport sector
with some changes from one country to another,
mostly by internal combustion engines. This
corresponds to 50% of the total oil production. The
share of the passenger cars within this
consumptions is about 50% in the developed
countries, resulting in a contribution of more than
25% to the CO2 production as well as for other
pollutant such as CO, HC, NOx and PM.
Considering these outcomes, the research and
developments activities in the automotive sector is
now concentrated on the reduction of pollutant and
improvement of fuel economy rather than
concentrating on reliability, durability and low cost
production as it was previously.
Lower CO2 emission limits set by the authorities
force the producers to build vehicles which
consume less fuel on a given standard driving
cycle. These test cycles, partly because of their
simplicity and partly because of the requirement of
standard test conditions, do not reflect the actual
driving conditions on the road with respect to both
for fuel consumption and for emissions
(Charbonnier (1993), Cayot (1995)). To determine
the emission rates more accurately complex
cycles and on board measurement methods
(such as mini CVS systems) were developed and
used (Andre (1996), Andre (1991), Andre,
Hickman, et. al. (1995), Andre, Vidon, et. al.
(1995), Andre, (1995), Andre, Joumard, et. al.
(1991)).
When a representative driving cycle is determined,
total emission for the component i (including CO2
as a measure of fuel consumption) at any point of
the cycle can be calculated according to the below
expression, if emission factor (aij ) is known :
n
jjijikmlkmgagE 1))()/(()(
where aij is the emission factor valid for the
distance interval
lj.
Emission factors depend on the other hand on
road parameters (such as slope angel), driving
behaviours (velocity, acceleration or correlation
between velocity and acceleration, idle durations
etc) and on driver habits (keeping constant
velocity, softer or harder accelerating drive style,
the using style of throttle pedal). Tests have
shown that driver also has an important influence
on the emissions and between the drivers
variation of up to 20% is possible with regard to
the emission rate, although this difference is much
lower for fuel consumption (Klingenberg (1995)).
Determination of the real emission factors require
considerable number of experiments. To reduce
the cost and the time, global emission factors
depending on the average velocity (or average
power) of the representing driving cycle may be
used for the estimation of greenhouse gas
emissions. Realistic emission value or fuel
consumption may be obtained for extra urban road
or motorway traffic by using such data, but this
method is not sufficient enough for the
determination of real emission load in the city or
on the main streets.
A more accurate but a complex way to calculate
the emissions and fuel consumption on a driving
cycle is by using fuel consumption and the
emission map of the engine. So it is possible to
obtain the emission rates point by point by
calculating the power demand of the vehicle on
the driving cycle and feeding back (by considering
the efficiency of the power train assembly) to the
engine map. This method is of course time
consuming and rather expensive, because every
engine must be tested on a dynamometer and
emissions must be measured. Besides, the engine
map does not generally reflect the dynamic
behaviour of the engine (instantaneous speed and
throttle valve position changes) with regard to
emissions.
Another way to obtain the real emissions on a
driving cycle is to use instantaneous emission
factors instead of the average values. For this
purposes the vehicle is tested for certain velocity,
accelerations and/or acceleration-velocity intervals
(or real time measurement on the road) and the
three dimensional (instantaneous) emission map
of the vehicle is obtained from the recorded data
(Sturm (1996)). Even with this method there are
differences up to 20 to 30% between the
calculations and the experiments depending on
the emission type and/or the driving cycle
considered. The difference between the emission
factors obtained by various methods becomes
higher for lower velocities (Zachariadis (1996)).
This may be due to the fact that the relatively
higher accelerations correlate well with the
relatively lower velocities, building operation points
which cover large percentage in total emissions.
Another problem encountered at the determination
of real emission rates is the effect of the road
gradient on emission factors. Generally, the
increase in emission values when travelling uphill
can not be compensated by the reduction obtained
when travelling downhill. This is the case even for
fuel consumption (CO2 emission) in the city
conditions, although it can be an acceptable
approximation for fuel consumption during intercity
travels. Because of higher total mass to engine
power ratio the impact of gradient on emission is
more important for heavy duty vehicles (or for light
duty vehicles) than passenger cars. But for the
special road conditions this effect may gain weight
for passenger cars too. For slopes higher than 2%
it is assumed that the driving cycles (driving
behaviours) are effected by the slopes. For this
reason special cycles are needed to simulate the
driving behaviour truly for road gradients more
than 2%. Emission factors for various road
gradients must also be multiplied by a gradient
factor (GF) which depends on the slope angle and
the mean speed. Its value is for CO, for example,
2 for +2 % gradient and for the cars without a
catalyst, although fuel consumption increase by
only 1.2 for the same condition (Hassel (1996)).
In this study the effect of driving pattern on
emission and fuel consumption of passenger cars
is investigated performing tests with selected
vehicles on several different driving cycles
including urban cycle obtained for Istanbul from
collected road data.
EFFECT OF DRIVING PATTERNS ON
EMISSIONS and FUEL CONSUMPTION
The driving behaviour due to traffic flow
restrictions has considerable influence on fuel
economy as well as exhaust gas emissions.
Although standard test cycles can be used to
estimate emissions and fuel consumption values
per unit distance travelled for a passenger car
fleet in a given region, more realistic approach
requires the determination of realistic driving
patterns for that region. In this study fuel
consumption and emission measurements
obtained using NEDC (European Driving Cycle)
and FTP75 (US Federal Test Cycle) (Figure 1.)
has been compared with the measurements
obtained by a specific cycle developed for the city
of Istanbul (Figure 2.).
The tests were done with thirty passenger cars for
all three cycles under laboratory conditions on a
chasis dynamometer. The distribution of age and
emission technology of those vehicles were
chosen to represent the passenger car fleet in
Turkey.
In this study only gasoline fueled spark ignition
engines were considered. The present passenger
car fleet consists of four different emission
technologies. The cars registered prior to model
year 1994 contain no emission control system.
During the following years emission standards
were introduced gradually, thus vehicle categories
of R15.04, EURO 1, EURO 3 and EURO 4 were
considered in this study.
Tests were conducted according to the NEDC and
FTP standards and the average value calculated
for each emission group is given in Table 1 for
both fuel consumption and CO2 emissions. IDC
(Istanbul Drive Cycle) is also applied to all vehicles
tested and the measured values are also
compared with the defaults given by IPCC (IPCC
1996, IPCC 2006).
For gasoline fuelled internal combustion engines,
changes in equivalence ratio during the operation
of the vehicle considerably effects the emissions,
especially CO and unburned HC’s. Although
equivalence ratio is electronically controlled for
precise adjustment and set at a stoichiometric
value, some instantaneous changes during
operation such as cold start, acceleration,
maximum power etc effects fuel economy as well
as pollutant emissions. Heavy traffic condition in
the city center resulting in congestion forces long
idle operations, rapid acceleration-decelleration of
the vehicle. These effects have clearly been
observed in IDC when compared with standard
cycles such as EU test cycle. Especially for
vehicles which do not posses any emission control
devices (uncontrolled, UC group), fuel
consumption is considerable increased with tests
according to IDC. In general the amount of CO2
produced during the combustion process has a
close correlation with fuel consumption. But UC
group cars in general have lower combustion
efficiency compared to vehicles satisfying EURO 3
and 4 standards. Therefore although fuel
consumption can be high with UC group cars, CO2
emissions do not follow the same trend while CO
and unburned HC emissions are increasing.
Test according to FTP cycle on the other hand
provided the lowest fuel consumption for all
vehicle groups. Although acceleration and
deceleration of the vehicle is effective in the FTP
cycle, the maximum vehicle velocity is lower than
NEDC cycle and the average velocity is higher
than IDC cycle to improve fuel economy.
Laboratory tests were conducted with no effects
due to the road gradient in standard tests as well
as IDC. Some reduction in the fuel consumption
measurements due to this effect can be expected.
CONCLUSION
IDC representing the real world driving conditions
result in higher fuel consumption and CO2
emission values due to the highly loaded traffic
conditions in the city of Istanbul. Large idle
operation durations and extremely low speed
driving provided an increase in fuel consumption
in comparison to the other driving cycles.
(a) New European Driving Cycle (NEDC)
(b) Federal Test Cycle , USA (FTP75)
Figure 1. Standard Emission Test Cycles
Figure 2. Istanbul Driving Cycle (IDC)
Table 1. Fuel consumption and CO2 emissions obtained by using different driving cycles.
Developments in vehicle technology considerably
reduced fuels consumption values together with
greenhouse gas emissions per vehicle in recent
years. The shifting of average vehicle age in the
car fleet to more recent model years will therefore
provide an important reduction in CO2 emissions.
Some results of this issue has been observed
recently in Turkey with the removal of 320,000
passenger cars from traffic by providing tax
advantages to consumers.
Traffic flow has considerable influence on fuel
consumption and CO2 emissions as demonstrated
with different test cycles for the same sample of
cars in this study. The arrangement of the traffic
flow through traffic management and planning will
be effective. But, as the improvement of fuel
consumption values per each car due to
technological developments would not be enough
in satisfying the greenhouse gas mitigation
targets, utilization of alternative transport modes
with lower emissions per passenger-km values is
also required.
ACKNOWLEDGMENTS
The authors acknowledge the support provided by
TUBITAK (The Scientific and Technological
Research Council of Turkey) through the project
entitled The Reduction of Greenhouse Gas
Emissions Resulting from the Transport Sector in
Turkey, No. 105G039.
REFERENCES
Charbonnier, M.. A.. , Andres, M. (1993), "A
comparative study of gasoline and diesel
passenger car emissions under similar
conditions of use", SAE Technical Paper
Series 930779, International Congress and
Exposition Detroit, Michigan, March 1-5, 1993,
121-129
Cayot, J.F., (1995), "The fight against
automotive pollution. An opportunity or a
threat for diesel engines ?", Istanbul First
International Automotive Industry and Environment
Conference and Exhibition, May 1995, 113-122
Andre, M., (1996), “Vehicles uses derived
driving cycles : a review of researches”, COST
319, Estimation of pollutant emissions from
transport, Proceedings of the workshop, 27-28
November 1995, Brussels, 99-109
Andre, M., (1991), "In actual use car testing:
70.000 kilometres and 10.000 trips by 55 french
cars under real conditions", SAE Technical
Paper Series 910039, International Congress and
Exposition Detroit, Michigan, February 25 - March
1, 1991
Andre, M., Hickman, A.J., Hassel, D., Joumard,
R., (1995), "Driving cycles for emissions
measurements under European conditions",
SAE Technical Paper Series 950926, International
Congress and Exposition Detroit, Michigan,
February 27 - March 2, 1995, 193-205
Andre, M., Vidon, R., Tassel, P., Olivier, D.,
Pruvost, C., (1995), "A method for assesing
energetic and environmental impact of traffic
changes in urban areas using instrumented
vehicles", 7th WCTR. World Conference on
Transport Research, Sydney Australia, July 16-21,
1995
Andre, M.,(1995), "A review of Researches
dealing with Vehicles Uses and Operating
conditions, and derived Driving Patterns or
Driving Cycles", International Workshop on
Vehicle Driving Cycles: Measurement, Analysis
and Synthesis, Ottawa, April 6-7, 1995
Andre, M., Joumard, R., Hickman, A.J., Hassel,
D., (1991), "Actual Car Use And Operating
Conditions As Emission Parameters; Derived
Urban Driving Cycles", INRETS, TRRL, CEDIA,
TÜV Rheinland
Klingenberg, H., (1995), “Automobil Meßtechnik,
Band C: Abgasmeßtechnik”, Springer-Verlag,
Berlin
Sturm, P.J., Sudy, C., (1996), “Instantaneous
Emission Maps- Available Data Sets and Use
of Data”, COST 319, Estimation of pollutant
emissions from transport, Proceedings of the
workshop, 27-28 November 1995, Brussels , 19-
28
Zachariadis, T., Samaras, Z., (1996),
“Comparison of Microscale and Macroscale
Traffic Emission Estimation Tools: DGV,
COPERT AND KEMIS”, COST 319, Estimation of
pollutant emissions from transport, Proceedings of
the workshop, 27-28 November 1995, Brussels,
135-145
Hassel, D., (1996), Gradient Influence on
Emission and Consumption Behaviour of Light
and Heavy Duty Vehicles”, COST 319,
Estimation of pollutant emissions from transport,
Proceedings of the workshop, 27-28 November
1995, Brussels, 39-49
IPCC, Revised 1996 IPCC Guidelines for
National Greenhouse Gas Inventories :
Reffernce Manual, Vol. 3, London, 1996.
IPCC, 2006 IPCC Guidelines for National
Greenhouse Gas Inventories, Vol. 1, Japan,
2006.
... The most common of these methodologies is to create an acceleration distribution matrix with respect to the average velocity (or named in literature, speed acceleration frequency distribution (SAFD)). Thanks to this matrix, the driving dynamics of the traffic are extracted, and cycles that better reflect the real driving conditions can be obtained [5,15,26,27]. ...
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The fight against automotive pollution. An opportunity or a threat for diesel engines ?", Istanbul First International Automotive Industry and Environment Conference and Exhibition
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Cayot, J.F., (1995), "The fight against automotive pollution. An opportunity or a threat for diesel engines ?", Istanbul First International Automotive Industry and Environment Conference and Exhibition, May 1995, 113-122
Vehicles uses derived driving cycles : a review of researches
  • M Andre
Andre, M., (1996), "Vehicles uses derived driving cycles : a review of researches", COST 319, Estimation of pollutant emissions from transport, Proceedings of the workshop, 27-28 November 1995, Brussels, 99-109
A method for assesing energetic and environmental impact of traffic changes in urban areas using instrumented vehicles
  • M Andre
  • R Vidon
  • P Tassel
  • D Olivier
  • C Pruvost
Andre, M., Vidon, R., Tassel, P., Olivier, D., Pruvost, C., (1995), "A method for assesing energetic and environmental impact of traffic changes in urban areas using instrumented vehicles", 7th WCTR. World Conference on Transport Research, Sydney Australia, July 16-21, 1995
Instantaneous Emission Maps-Available Data Sets and Use of Data
  • P J Sturm
  • C Sudy
Sturm, P.J., Sudy, C., (1996), "Instantaneous Emission Maps-Available Data Sets and Use of Data", COST 319, Estimation of pollutant emissions from transport, Proceedings of the workshop, 27-28 November 1995, Brussels, 19-28
Comparison of Microscale and Macroscale Traffic Emission Estimation Tools Estimation of pollutant emissions from transport
  • T Zachariadis
  • Z Samaras
  • Dgv
  • Copert
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Zachariadis, T., Samaras, Z., (1996), " Comparison of Microscale and Macroscale Traffic Emission Estimation Tools: DGV, COPERT AND KEMIS ", COST 319, Estimation of pollutant emissions from transport, Proceedings of the workshop, 27-28 November 1995, Brussels, 135-145
Gradient Influence on Emission and Consumption Behaviour of Light and Heavy Duty Vehicles
  • D Hassel
Hassel, D., (1996), "Gradient Influence on Emission and Consumption Behaviour of Light and Heavy Duty Vehicles", COST 319, Estimation of pollutant emissions from transport, Proceedings of the workshop, 27-28 November 1995, Brussels, 39-49