4a cleaner fuels and vehicle technologies
TRANSCRIPT
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Module 4aCleaner Fuels and Vehicle Technologies
Sustainable Transport:
A Sourcebook for Policy-makers in Developing Cities
Division 44
Environment and Infrastructure
Sector project: Transport Policy Advice
Deutsche Gesellschaft frTechnische Zusammenarbeit (GTZ) GmbH
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Overview of the sourcebook
Sustainable Transport: A Sourcebook
for Policy-Makers in Developing Cities
What is the Sourcebook?
This Sourcebookon Sustainable Urban Transportaddresses the key areas of a sustainable transportpolicy framework for a developing city. TheSourcebookconsists of 20 modules.Who is it for?
The Sourcebookis intended for policy-makersin developing cities, and their advisors. Thistarget audience is reected in the content, whichprovides policy tools appropriate for applicationin a range of developing cities.
How is it supposed to be used?
The Sourcebookcan be used in a number ofways. It should be kept in one location, and thedifferent modules provided to ofcials involvedin urban transport. The Sourcebookcan be easilyadapted to t a formal short course trainingevent, or can serve as a guide for developing acurriculum or other training program in the areaof urban transport; avenues GTZ is pursuing.
What are some of the key features?
The key features of the Sourcebookinclude:A practical orientation, focusing on best
practices in planning and regulation and,where possible, successful experience indeveloping cities.Contributors are leading experts in their elds.An attractive and easy-to-read, colour layout.Non-technical language (to the extentpossible), with technical terms explained.Updates via the Internet.
How do I get a copy?
Please visit www.sutp-asia.org or www.gtz.de/transport for details on how to order a copy. The
Sourcebookis not sold for prot. Any chargesimposed are only to cover the cost of printingand distribution.
Comments or feedback?
We would welcome any of your comments orsuggestions, on any aspect of the Sourcebook, byemail to [email protected], or by surface mail to:Manfred BreithauptGTZ, Division 44Postfach 518065726 Eschborn
Germany
Modules and contributors
Sourcebook Overview; and Cross-cutting Issues ofUrban Transport(GTZ)Institutional and policy orientation
1a.The Role of Transport in Urban DevelopmentPolicy(Enrique Pealosa)1b.Urban Transport Institutions(Richard Meakin)1c. Private Sector Participation in Transport Infra-
structure Provision (Christopher Zegras,MIT)1d.Economic Instruments(Manfred Breithaupt,
GTZ)1e. Raising Public Awareness about Sustainable
Urban Transport(Karl Fjellstrom, GTZ)Land use planning and demand management
2a.Land Use Planning and Urban Transport
(Rudolf Petersen, Wuppertal Institute)2b. Mobility Management(Todd Litman, VTPI)Transit, walking and cycling
3a.Mass Transit Options(Lloyd Wright, ITDP;Karl Fjellstrom, GTZ)
3b.Bus Rapid Transit(Lloyd Wright, ITDP)3c. Bus Regulation & Planning(Richard Meakin)3d.Preserving and Expanding the Role of Non-
motorised Transport(Walter Hook, ITDP)Vehicles and fuels
4a.Cleaner Fuels and Vehicle Technologies
(Michael Walsh; Reinhard Kolke,Umweltbundesamt UBA)4b.Inspection & Maintenance and Roadworthiness
(Reinhard Kolke, UBA)4c. Two- and Three-Wheelers(Jitendra Shah,
World Bank; N.V. Iyer, Bajaj Auto)4d.Natural Gas Vehicles(MVV InnoTec)Environmental and health impacts
5a.Air Quality Management(Dietrich Schwela,World Health Organisation)
5b.Urban Road Safety(Jacqueline Lacroix, DVR;David Silcock, GRSP)
5c. Noise and its Abatement(Civic ExchangeHong Kong; GTZ; UBA)
Resources
6. Resources for Policy-makers(GTZ)Further modules and resources
Further modules are anticipated in the areasofDriver Training; Financing Urban Transport;Benchmarking; and Participatory Planning. Ad-ditional resources are being developed, and anUrban Transport Photo CD (GTZ 2002) is now
available.
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I
Module 4aCleaner Fuels and
Vehicle Technologies
Findings, interpretations and conclusionsexpressed in this document are based on infor-mation gathered by GTZ and its consultants,partners, and contributors from reliable sources.GTZ does not, however, guarantee the accuracyor completeness of information in this docu-ment, and cannot be held responsible for any
errors, omissions or losses which emerge fromits use.
About the authors
Reinhard Kolke is an engineer of environmen-tal and energy science. He graduated from FH
Aachen with a thesis on fuel chain analysis foralternative vehicles. Since 1993 he has workedat the German Federal Environmental Agency(UBA) as an expert for future technologies forroad trafc and carbon dioxide reduction strate-gies in the trafc sector. Other interests includein-use compliance and inspection and main-tenance. He is one of the authors of the UBAstudies Passenger Cars 2000 and Heavy DutyVehicles 2000, prepared for the discussion ofEuropean emission standards EURO III and IV,
as well as the author of a study about fuel cellsin transportation.
Michael P. Walsh is a mechanical engineer whohas spent his entire career working on motorvehicle pollution control issues at the local,national, and international level. For the rsthalf of his career to date, he was in governmentservice, initially with the City of New York andsubsequently with the U.S. Environmental Pro-tection Agency. With each, he served as Director
of their motor vehicle pollution control efforts.
Since leaving government, he has been an inde-pendent consultant advising governments andindustries around the world. Michael P. Walshhas recently been selected as the rst recipient
of the U.S. Environmental Protection Agencylifetime achievement award for air pollutioncontrol. The award, in honour of Thomas W.Zosel, was given for outstanding achievement,demonstrated leadership, and a lasting commit-ment to promoting clean air.
Author:Michael WalshReinhard Kolke (Umweltbundesamt)
Editor:Deutsche Gesellschaft fr
Technische Zusammenarbeit (GTZ) GmbHP.O. Box 51 8065726 Eschborn, Germanyhttp://www.gtz.de
Division 44, Environment and InfrastructureSector Project Transport Policy AdviceCommissioned byBundesministerium fr wirtschaftlicheZusammenarbeit und Entwicklung (BMZ)Friedrich-Ebert-Allee 4053113 Bonn, Germanyhttp://www.bmz.deManager:Manfred Breithaupt
Editorial Board:Manfred Breithaupt, Karl Fjellstrom, Stefan Opitz,Jan Schwaab
Cover photo:Karl FjellstromA refueling station in Curitiba, Brazil, Feb. 2002
Layout:Karl Fjellstrom
Print:TZ Verlagsgesellschaft mbHBruchwiesenweg 19, 64380 Rodorf, Germany
Eschborn, 2002
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II
1. Background and introduction 1
2. Integrated strategies to reduceemissions from vehicles 2
3. Fuel quality standards 3
4. Gasoline 3
4.1 Lead additives 3
4.2 Sulfur 4
4.3 Vapour pressure 4
4.4 Benzene 5
4.5 Oxygenates 5
Impact of oxygenate used 5
4.6 Other gasoline properties 5
5. Diesel fuel 6
5.1 Impact on emissions fromheavy duty engines 6
5.2 Impact on emissions from
light duty vehicles 7
5.3 Sulfur 8
5.4 Other diesel fuel properties 8
Volatility 8 Aromatic hydrocarbon content 8
Other properties 9
5.5 Fuel additives 10
6. Alternative fuels 11
6.1 Natural gas (NG) 11
6.2 Liqueed petroleum gas (LPG) 14
6.3 Methanol 16
6.4 Ethanol 16
6.5 Biodiesel 176.6 Hydrogen (H
2 ) 18
Costs, other restrictions 18
6.7 Electric vehicles 18
Greenhouse gases, other emissions 19
Costs, other restrictions 19
6.8 Fuel cells 19
Greenhouse gases, other emissions 19
Costs, other restrictions 20
7. Conclusions 24
Further information 25
Endnotes 25
Other references 26
Recommended Websites 27Some common abbreviations 27
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Module 4a: Cleaner Fuels and Vehicle Technologies
Cleaner fuels and vehicle
technologies in ThailandAdapted from message of Horst Preschern to CAI-Asia list,
8 Oct. 2002
When excluding the industrialized countries
what you have is a great mix of levels on emission
legislation, fuel quality, manufacturing capabilities,
buying power, and so on. Only the strongest amongst
them (such as Thailand) have managed to bring
sustainable improvements to all sectors: Thailand
has EURO regulations in force, will soon switch
to EURO III for diesel pick-ups, have consequently
worked on fuel quality (invested good money in own
fuel & lubricants research), have now low sulfur dieselavailable to allow EURO III emission levels to be met,
and have built up the manufacturing infrastructure
together with the Original Equipment Manufacturers
or licensors so that a substantial amount of vehicle
is manufactured locally; even including engines.
Many of the others? Spare me to name coun-
tries: No emission legislation in force, leaded gasoline
prevailing, diesel with high sulfur component, fuel
prices highly subsidised thus little interest in im-
proving quality.
1. Background and introduction
Motor vehicles emit large quantities of carbonmonoxide, hydrocarbons, nitrogen oxides, and
such toxic substances as ne particles and lead.Each of these, along with secondary by-productssuch as ozone, can cause serious adverse effectson health and the environment. Because of thegrowing vehicle population and the high emissionrates from many of these vehicles, serious airpollution and health effect problems have beenincreasingly common phenomena in modern life.
Over the course of the past 30 years, pollutioncontrol experts around the world have cometo realize that cleaner fuels must be a critical
component of an effective clean air strategy. Inrecent years, this understanding has grown anddeepened and spread to most regions of the world.Fuel quality is now seen as not only necessaryto reduce or eliminate certain pollutants(e.g.,lead) directly but also aprecondition for the in-troduction of many important pollution controltechnologies (lead and sulfur). Further, onecritical advantage of cleaner fuels has emerged:its rapid impact on both new and existingvehicles. (For example, tighter new car standards
can take ten or more years to be fully effective
whereas lowering lead in gasoline will reducelead emissions from all vehicles immediately.)
Fig. 1
Integrated airquality managementframework.
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
2. Integrated strategies to reduceemissions from vehicles
In developing strategies to clean up vehicles, it is
necessary to start from a clear understanding ofthe emissions reductions from vehicles and othersources that will be necessary to achieve healthyair quality. Depending upon the air qualityproblem and the contribution from vehicles,the degree of control required will differ fromlocation to location. As illustrated in Figure 1regarding an Integrated Air Quality Manage-ment Framework, one should start with a carefulassessment of air quality and the sources thatare contributing the most to the problem orproblems.
Where vehicles are the major culprits, a broadbased approach to the formulation and im-plementation of policies and actions aimed atreducing their pollution will be needed.
Effective and efcient coordination mechanismsfor the management of pollution from vehiclesmust be established. This should also includea clear allocation of responsibilities for specicfunctions and tasks to individual agencies andorganizations.
Reducing the pollution from motor vehicleswill usually require a comprehensive strategy.Generally, the goal of a motor vehicle pollutioncontrol program is to reduce emissions from
motor vehicles in-use to the degree reason-ably necessary to achieve healthy air quality asrapidly as possible or, failing that for reasons ofimpracticality, to the practical limits of effectivetechnological, economic, and social feasibility.
One should start with a careful
assessment of air quality and the
sources that are contributing the
most to the problem or problems
A comprehensive strategy to achieve this goalincludes four key components (see Figure 2): in-creasingly stringent emissions standards for newvehicles, specications for clean fuels, programsto assure proper maintenance of in-use vehicles,and transportation planning and demand man-agement. These emission reduction goals shouldbe achieved in the most cost effective manneravailable.
Fig. 2
Elements of acomprehensive
vehicle pollutioncontrol strategy.
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Module 4a: Cleaner Fuels and Vehicle Technologies
3. Fuel quality standards
In setting fuel quality standards, policy-mak-ers should be guided by the following general
principles:Because the environment and publichealth concerns are the driving forcebehind improvements in fuel quality theenvironment department should have a majorrole in setting fuel standards.All countries should develop a short andmedium term strategy that outlines proposedstandards to be adopted over the next severalyears so as to allow fuel providers and thevehicle industry sufcient time to adapt.The most important impediment toadopting state of the art new vehicle emissiontechnology (equivalent to Euro III and IV) inmany countries is the fuel quality, especiallythe level of lead and sulfur in gasoline andthe level of sulfur in diesel. These parametersshould receive highest priority in thedevelopment of medium and long-termstrategies for fuel standards.In developing fuel standards, countries shouldattempt to work closely with neighboringcountries and to harmonize standards where
possible. This should not be used as an excusefor delaying or watering down requirementsas harmonization does not mean that everycountry must follow the same time schedule.In order to implement stricter fuel standardsand increase the acceptability of the associatedcosts to consumers, countries should institutemore and better awareness campaigns. Suchcampaigns must emphasize the public healthconsequences of not improving fuel quality.Subsidies that favour fuels that result in
high emissions should be eliminated and taxpolicies should be adopted which encouragethe use of the cleanest fuels.
Conventional fuel improvements should clearlydistinguish between primary steps removinglead from gasoline and dramatically reducingsulfur in gasoline and diesel, and the addition ofdetergent additives and secondary steps suchas reducing the vapour pressure and benzenecontent of gasoline.
4. Gasoline
The pollutants of greatest concern from gaso-line-fuelled vehicles are carbon monoxide (CO),
hydrocarbons (HC), nitrogen oxides (NOx), leadand certain toxic hydrocarbons such as benzene.Each of these can be inuenced by the composi-tion of the gasoline used by the vehicle. Themost important characteristics of gasoline withregard to its impact on emissions are lead con-tent, sulfur concentration, volatility and benzenelevel. With regard to these characteristics, thefollowing policies are recommended.
4.1 Lead Additives
Lead does not exist naturally in gasoline but mustbe added to it. Since the early 1970s, however,there has been a steady movement toward reducedlead in leaded gasoline and increasingly, the elimi-nation of lead. Approximately 85% of all gasolinesold throughout the world is now unleaded.
Several comprehensive studies of the health issuehave been conducted over the past two decades
with the result that health concerns are increas-ingly emerging at lower and lower levels. Leadis now recognized to have a physiologic role inbiological systems, including human biology.Over the past century, a range of clinical, epide-miological and toxicological studies have contin-ued to dene the nature of lead toxicity and toidentify young children as a critically susceptiblepopulation. At low doses, lead is particularlytoxic to the brain, the kidney, the reproductivesystem, and the cardiovascular system. Its mani-festations include impairments in intellectualfunction, including problems in learning amongchildren, kidney damage, infertility, miscarriage,
and hypertension. At relatively high exposures,lead is lethal to humans, usually causing deathby inducing convulsions and irreversible hemor-rhage in the brain. Long-term exposures may beassociated with increased risks of kidney cancer.
A study by Schwartz estimated that in economicterms, the total benet of a 1 microgram perdeciliter reduction in blood lead levels for oneyears cohort of children in the United Statesis $6.937 billion, with $5.060 billion due toearnings losses as a result of loss of cognitive
ability and lower educational achievement and
Reformulation of
conventional fuels
Fuel modications can take
effect quickly and have a
particularly marked impact in
the case of existing vehicles
on the road.
On themotor gasoline front
the focus is on reducing:
Lead and sulfur content
(the primary steps)
Benzene
Aromatics content
Vapour pressure
Admixtures of oxygen-
containing compounds.
For diesel fuels the key
areas are: Reducing sulfur content
Reducing density
Reducing polyaromatics
Improving ignition proper-
ties (cetane number).
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
the remainder due to reduced infant mortality.1With a reduction in median blood lead levels inthe US from 1980 to 1990 of 6.4 micrograms/deciliter, this reects a savings of $44.4 bil-
lion over this time frame alone. Most of thisimprovement is due to the reduction of lead ingasoline during the same period.
The state of the art technology for reducingCO, HC and NO
xemissions from vehicles relies
on the catalytic converter which converts largeportions of the emissions to carbon dioxide,
water vapour, oxygen and nitrogen; in fact ap-proximately 90% of all new gasoline fueled carsmanufactured last year contained a catalyst.
Sulfur in gasoline should bereduced to a maximum of 500 ppm
as soon as new vehicle standards
requiring catalysts are introduced
This technology cannot be used with leadedgasoline, however, since lead poisons the cata-lyst. The US Environmental Protection Agencycarried out a study in which twenty-nine in useautomobiles with three-way catalyst emissioncontrol systems were misfueled with leaded
gasoline in order to quantify the emissionseffects. The results of the program indicatedthat vehicle emissions are mainly affected by theamount of lead passing through the engine andsecondarily by the rate of misfueling. Emissionsof HC, CO and NO
xgenerally increase steadily
with continuous misfueling.2
All modern gasoline fuelled vehicles being pro-duced today can operate satisfactorily on un-leaded fuel and approximately 90% of these areequipped with a catalytic converter that requiresthe exclusive use of lead-free fuel. There is nolonger any doubt that lead is toxic and preventsthe use of clean gasoline vehicle technology
which can dramatically reduce CO, HC andNO
xemissions. The addition of lead to gasoline
should be eliminated as rapidly as possible.
4.2 Sulfur
For cars without a catalytic converter, the impactof sulfur on emissions is minimal; however for
catalyst-equipped cars, the impact on CO, HC
and NOx
emissions can be substantial. Based onthe Auto/Oil study, it appears that NO
xwould
go down about 3% per 100 parts per million(ppm) sulfur reduction for a typical catalyst
equipped car.
3
The situation is even more critical for advancedlow pollution catalyst vehicles. Operation ongasoline containing 330 ppm sulfur will increaseexhaust VOC and NO
xemissions from current
and future new US vehicles (on average) by 40percent and 150 percent, respectively, relative totheir emissions with fuel containing roughly 30ppm sulfur.
In light of these impacts, it is not surprisingthat Japan has had typical gasoline sulfur levels
under 30 ppm for many years. The US has alsoadopted a 30 ppm sulfur limit and the EU re-quires gasoline with a maximum sulfur contentof no more than 50 ppm in 2005 when Euro 4standards go into effect. Even more recently, theEuropean Union has proposed to limit sulfurlevels to a maximum of 10 ppm.
In order to maximise the performance of cur-rent catalyst technology, sulfur concentrationsin gasoline should be reduced to a maximumof 500 ppm as soon as new vehicle standards
requiring catalysts are introduced. Emergingadvanced catalyst technologies that are capableof achieving very low emissions will requirea maximum of 50 ppm or less and a plan forintroducing such fuel quality should be adoptedat the early stages of development of a long termvehicle pollution control strategy.
4.3 Vapour Pressure
Another important fuel parameter is vapour
pressure. The vapour pressure for each seasonmust be as low as possible in order to minimiseevaporation from storage terminals and vehiclesbut still sufciently high to give safe cold starts.
An important advantage of gasoline volatilitycontrols is that they can affect emissions fromvehicles already produced and in-use and fromthe gasoline distribution system.
Gasoline vapour pressure should be reduced to amaximum of 60 kilopascals whenever tempera-tures in excess of 20 C are anticipated to occur.
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Module 4a: Cleaner Fuels and Vehicle Technologies
In tropical or semi-tropical countries, this ofcourse will be all the time.
4.4 Benzene
Benzene is an aromatic hydrocarbon that ispresent as a gas in both exhaust and evapoura-tive emissions from motor vehicles. Benzene inthe exhaust, expressed as a percentage of totalorganic gases (TOG), varies depending oncontrol technology (e.g., type of catalyst) andthe levels of benzene and other aromatics in thefuel, but is generally about three to ve percent.The benzene fraction of evapourative emissionsdepends on control technology and fuel com-position and characteristics (e.g., benzene level
and the evaporation rate) and is generally aboutone percent.4 As a general rule, benzene levelsin gasoline should be capped at 1% as has beendone in the European Union.
4.5 Oxygenates
Blending small percentages of oxygenatedcompounds such as ethanol, methanol, tertiarybutyl alcohol (TBA) and methyl tertiary-butylether (MTBE) with gasoline has the effect ofreducing volumetric energy content of the fuel,
while improving the antiknock performanceand thus making possible a potential reductionin lead and/or harmful aromatic compounds.
Assuming no change in the settings of the fuelmetering system, lowering the volumetric energycontent will result in a leaner air-fuel mixture,thus helping to reduce exhaust CO and HCemissions.
Impact of oxygenate used
MTBE
MTBE (methyl tertiary butyl ether) can beadded to gasoline up to 2.7% without anyincrease in NO
x. There are two opposing effects
taking place with the addition of oxygenates:enleanment, which tends to raise NO
x, and
lower ame temperatures, which tend to reduceNO
x. With MTBE levels above 2.7%, the lower
ame temperature effect seems to prevail.
While the use of MTBE has been found to bevery attractive from an air pollution point ofview, recent evidence in the US has shown that
leaks and spills are a serious threat to drinking
water. This has led to a movement toward aban on its use in gasoline in the future. TheEuropean Union has not reached a similarconclusion but prefers to improve the quality of
underground storage tanks.Countries considering the use of MTBE shouldcarefully weigh the potential air quality benets
with the potential water quality risks.
Ethanol
Ethanol can be added to gasoline at levels ashigh as 2.1% oxygen without signicantlyincreasing NO
xlevels but above that point NO
x
levels could increase somewhat. For example,EPA test data on over 100 cars indicates thatoxygen levels of 2.7% or more could increaseNO
xemissions by 3 4%.5 The auto/oil study
concluded that there was a statistically sig-nicant increase in NO
xof about 5% with the
addition of 10% ethanol (3.5% O2).
Since ethanol has a higher volatility than gaso-line, the base fuel volatility must be adjusted soas to prevent increased evapourative emissions.
As a general rule, without adjustment, volatilitywill increase by about 1 psi when ethanol isadded to gasoline.
Countries considering the use of ethanol shouldcarefully evaluate and weigh the tailpipe COand HC benets versus the potential NO
xand
evaporative hydrocarbon increases.
4.6 Other Gasoline Properties
According to the Auto/Oil study:
NOx
emissions were lowered by reducing olens,raised when T
90was reduced, and only marginally
increased when aromatics were lowered.6
In general, reducing aromatics and T90 causedstatistically signicant reductions in exhaustmass NMHC and CO emissions. Reducingolens increases exhaust mass NMHC emis-sions; however, the ozone forming potential ofthe total vehicle emissions was reduced.7
With regard to toxics, the reduction of aromaticsfrom 45% to 20% caused a 42% reduction inbenzene but a 23% increase in formaldehyde, a20% increase in acetaldehyde and about a 10%increase in 1,3-Butadiene.8 Reducing olens
from 20% to 5% brought about a 31% reduc-
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
etane number
he cetane number/value/
dex is a measure of die-
el fuel ignition quality. In
ompression-ignition (diesel)
ngines, it refers to the fuels
bility to react with oxygen
nder explosion conditions
nd hence enable the engine
produce shaft power. The
gher the cetane number, the
etter the performance.
toichiometric mixture
stoichiometric mixture is a
ixture of substances that
an react to give products
ith no excess reactant.
tion in 1,3-Butadiene but had insignicantimpacts on other toxics. Lowering the T
90from
360 to 280F resulted in statistically signicantreductions in benzene, 1,3-Butadiene (37%),
formaldehyde (27%) and acetaldehyde (23%).To the extent that the long-term vehicle emis-sions standards strategy is to adopt Europeanstep 4 (so called Euro 4) standards for light dutyvehicles, the European gasoline standards assummarized in Table 1 should be adopted in thesame timeframe.
Detergent or engine deposit control additives arecritically important with modern engines andshould be mandatory as well.
5. Diesel fuel
Diesel vehicles emit signicant quantities ofboth NO
xand particulate. Reducing PM emis-
sions from diesel vehicles tends to be the highestpriority because PM emissions in general arevery hazardous and diesel PM, especially, islikely to cause cancer. To reduce PM and NO
x
emissions from a diesel engine, the most impor-tant fuel characteristic is sulfur because sulfur infuel contributes directly to PM emissions andbecause high sulfur levels preclude the use of themost effective PM and NO
xcontrol technologies.
5.1 Impact On Emissions From Heavy
Duty EnginesA recent review addressed the impact of changesin fuel composition on emissions from currentheavy duty, direct-injection diesel enginesbased only on studies where there were no sig-nicant correlations among germane fuel prop-erties.9 Conclusions from this review are sum-marized in Table 2. As shown, compositionalproperties of at least some importance withrespect to emissions are sulfur, aromatic, and
Petrol/
Gasoline
Parameter
2000
(Linked
to Euro
3 Vehicle
Standards)
2005
(Linked
to Euro
4 Vehicle
Standards)
RVP summerkPa, max.
60 60
Aromatics%v/v, max.
42 35
Benzene%v/v, max.
1 1
Olens%v/v, max.
18 18
Oxygen%m/m, max.
2.7 2.7
Sulfur,ppm, max.
150 50
Table 1: European Union fuel specication
limits.
Key: / = Relatively large effect, / = smalleffect, / = very small effect, 0 = no effectA) Low emission emitting engineB) High emission emitting engineC) Polyaromatics are expected to give a biggerreduction than mono-aromatics. Furtherstudies (e.g. EPA HD engine working group) areinvestigating these parameters.D) Reducing S from 0.30% to 0.05% givesrelatively large benets; reducing S from 0.05%to lower levels has minimal direct benet but asdiscussed below is necessary to enable advancedtechnologies.
* for engines without aftertreatment systems
Fuel Modication NOx
Particulates
Reduce Sulfur* 0 D
Increase Cetane 0
Reduce TotalAromatics
C 0
Reduce Density 0A / B
Reduce Polyaromatics C 0A / b
Reduce T90/T95 0
Table 2: Summarised inuence offuel properties on heavy duty diesel
emissions.
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Module 4a: Cleaner Fuels and Vehicle Technologies
ChangeNO
xEmissions PM Emissions
IDIa DIb IDI DI
Cetane (50 to 58) NoneDensity (0.855 to 0.828 g/cm3) None
T95 (700 to 6201F) None
Polycyclics (8 to 1 vol %)
Key: Relatively large effects denoted / (10%or greater change in emissions); Small effectsdenoted / (5 to 10% change); Very small effectsdenoted / (~1 to 5% change).a) Indirect-injection enginesb) Direct-injection engines
Table 3: Impact of fuel composition changes on emissions
of current light-duty diesel vehicles.
oxygenate content; the physical properties iden-tied are density and the T90 or T95 distillationtemperature. The cetane number/index was alsoidentied as a factor with respect to emissions.
The directional changes in these fuel properties,which will result in a cleaner fuel, are shownby the arrows in the rst column of the table.The directional impact on emissions of NO
x,
PM, HC, and CO resulting from changes ineach property in the direction indicated are alsoshown, along with an indication of the relativemagnitude of the effect.
As shown in Table 2, emissions from engineswith high base emission rates (generally olderdesigns) tend to be more sensitive to changes in
fuel composition than those from engines withlower base emissions rates (which tend to benewer designs). In addition, changes in all of thefuel properties have been found to have, at most,small impacts on emissions from engines withlow base emission rates.
5.2 Impact on Emissions From Light
Duty Vehicles
The most recent, comprehensive, study of fuelcomposition impacts on light-duty diesel emis-
sions was performed as part of the EuropeanPrograms on Emissions, Fuels and EngineTechnologies (EPEFE).10 The generalized resultsof this study are presented in Table 3. As shown,although there are some differences in termsof the magnitude of fuel composition effectson emissions from vehicles with indirect- anddirect-injection engines, the directional impacton emissions is usually the same.
A comparison of the heavy duty and light dutytables indicates that there are some instances
where changing a given diesel fuel property isexpected to have the opposite directional impacton emissions depending on whether the fuel isbeing used in a heavy duty engine or light-dutyvehicle. The most notable are the increase inNO
xemissions from light-duty direct-injection
engines in response to a decrease in fuel densityand the increases in NO
xemissions from both
light-duty indirect- and direct-injection enginesin response to a decrease in the T95 temperature.11
Fuel policy gets more teethin India
Adapted from: Times of India, 28 Sept. 2002; CAI-Asia list,
1 Oct. 2002
Eleven cities in India are slated for more strin-gent vehicular emission norms under the auto
fuel policy formulated by an expert committee set
up last year to look into the issues of fuel quality
and auto technology, submitted this week to the
ministry of petroleum and natural gas. The report
proposes two separate road maps; one for new ve-
hicles and one for old ones, to improve fuel quality
and vehicle emissions. It marks out Delhi, Kolkata,
Mumbai, Chennai, Hyderabad, Ahmedabad, Surat,
Pune, Bangalore, Kanpur and Agra for stricter stan-
dards.
According to the schedule set by the report,
new vehicles in these cities would have to meet
Euro III norms by 2005 and Euro IV emission norms
by 2010. The rest of the country will only get these
standards ve years later.
For two and three wheelers, the committee re-
commends Bharat stage II norms, the equivalent
of Euro II, by 2005. Vehicles that are already in
use, however, will have it much easier. The report
recommends that emission norms for buses and
taxis registered before 2004 should be required
to meet 1996 norms or Euro 1 by that time, and
those registered before 2008, meet Euro II norms
by that year.[Note: This report covers many other areas of transport policy.
To download a copy, please see www.petroleum.nic.in/afp_
con.htm].
http://www.petroleum.nic.in/afp_con.htmhttp://www.petroleum.nic.in/afp_con.htmhttp://www.petroleum.nic.in/afp_con.htmhttp://www.petroleum.nic.in/afp_con.htm -
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
5.3 Sulfur
Sulfate particulate and SOx
emissions, both ofwhich are harmful pollutants, are emitted indirect proportion to the amount of sulfur in
diesel fuel. Sulfate PM contributes to PM10, andPM
2.5emissions directly with their associated
adverse health and environmental effects. SO2,
one fraction of the SOx, is a criteria pollutant
with associated adverse effects. The health andwelfare effects of SO
2emissions from diesel vehi-
cles are probably much greater than those of anequivalent quantity emitted from a utility stackor industrial boiler, since diesel exhaust is emit-ted close to the ground level in the vicinity ofroads, buildings, and concentrations of people.
Further some of the SOx are also transformed inthe atmosphere to sulfate PM with the associ-ated adverse effects noted for PM.
The presence of sulfur in diesel
fuel effectively bars the path to low
emissions of conventional pollutants
Diesel PM consists of three primary constituents- a carbonaceous core, a soluble organic fraction(SOF) which sits on the surface of this core
and a mixture of SOx and water, which also sitson the surface of the core. Lowering the sulfurin the fuel lowers the SO
xfraction of PM thus
lowering the overall mass of PM emitted. Dieselfuel evaluations carried out in Europe showthe benets of reduced sulfur in diesel fuel forlowering particulates. For example, lowering thediesel fuel sulfur level from 2000 ppm to 500ppm reduced overall particulate from light dutydiesels by 2.4% and from heavy duty diesels by13%.12 The relationship between particulates
and sulfur level was found to be linear; for every100 ppm reduction in sulfur, there will be a0.16% reduction in particulate from light dutyvehicles and a 0.87% reduction from heavy dutyvehicles.
Sulfur in diesel fuel has a comparable technologyenabling effect as lead and sulfur in gasoline.Catalytic converters or NO
xadsorbers can
eliminate much of the NOx
emissions from newdiesel engines, but sulfur disables them in muchthe same way that lead poisons the three-way
catalyst. Thus, the presence of sulfur in diesel
fuel effectively bars the path to low emissions ofconventional pollutants. As stated by the Ger-man government in a petition to the EuropeanCommission in support of low sulfur fuel:
A sulfur content of 10 ppm compared to 50 ppmincreases the performance and durability of oxidiz-ing catalytic converters, DeNO
xcatalytic convert-
ers and particulate lters and therefore decreasesfuel consumption. There are also lower particulateemissions (due to lower sulfate emissions) withoxidizing catalytic converters. For certain continu-ously regenerating particulate lters, a sulfurcontent of 10 ppm is required for the simple reasonthat otherwise the sulfate particles alone (withoutany soot) would overstep the future [European]particulate value of 0.02 g/kWh.
In addition to its role as a technology enabler,low sulfur diesel fuel gives benets in the formof reduced sulfur induced corrosion and sloweracidication of engine lubricating oil, leading tolonger maintenance intervals and lower mainte-nance costs. These benets can offer signicantcost savings to the vehicle owner without theneed for purchasing any new technologies.
5.4 Other Diesel Fuel Properties
Volatility
Diesel fuel consists of a mixture of hydrocarbonshaving different molecular weights and boilingpoints. As a result, as some of it boils away onheating, the boiling point of the remainderincreases. This fact is used to characterise therange of hydrocarbons in the fuel in the form ofa distillation curve specifying the temperatureat which 10%, 20%, etc. of the hydrocarbonshave boiled away. A low 10% boiling point isassociated with a signicant content of relatively
volatile hydrocarbons. Fuels with this charac-teristic tend to exhibit somewhat higher HCemissions than others.
Aromatic hydrocarbon content
Aromatic hydrocarbons are hydrocarbon com-pounds containing one or more benzene-likering structures. They are distinguished fromparafns and napthenes, the other major hydro-carbon constituents of diesel fuel, which lacksuch structures. Compared to these other com-ponents, aromatic hydrocarbons are denser, havepoorer self-ignition qualities, and produce more
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Module 4a: Cleaner Fuels and Vehicle Technologies
soot in burning. Ordinarily, straight run dieselfuel produced by simple distillation of crude oilis fairly low in aromatic hydrocarbons. Catalyticcracking of residual oil to increase gasoline and
diesel production results in increased aromaticcontent, however. A typical straight run dieselmight contain 20 to 25% aromatics by volume,
while a diesel blended from catalytically crackedstocks could have 40 50% aromatics.
Aromatic hydrocarbons have poor self-ignitionqualities, so that diesel fuels containing a highfraction of aromatics tend to have low Cetanenumbers. Typical Cetane values for straightrun diesel are in the range of 50 55; thosefor highly aromatic diesel fuels are typically 40
to 45, and may be even lower. This producesmore difculty in cold starting, and increasedcombustion noise, HC, and NO
xdue to the
increased ignition delay.
Increased aromatic content is also correlatedwith higher particulate emissions. Aromatichydrocarbons have a greater tendency to formsoot in burning, and the poorer combustionquality also appears to increase particulate solu-ble organic fraction (SOF) emissions. Increasedaromatic content may also be correlated with
increased SOF mutagenicity. There is also someevidence that more highly aromatic fuels havea greater tendency to form deposits on fuelinjectors and other critical components. Suchdeposits can interfere with proper fuel/air mix-ing, greatly increasing PM and HC emissions.
Polycyclic aromatic hydrocarbons (PAH) areincluded in the great number of compoundspresent in the group of unregulated pollutantsemitted from vehicles. Exhaust emissions ofPAH (here dened as three ringed and larger)
are distributed between particulate- and semi-volatile phases. Some of these compounds in thegroup of PAH are mutagenic in the Ames testand even in some cases causes cancer in animalsafter skin painting experiments. Because of thisfact, it is of importance to limit the emissions ofPAH from vehicles especially in densely popu-lated high trafc urban areas. An important fac-tor affecting the emissions of PAH from vehiclesis selection of fuel and fuel components. A linearrelationship exists between fuel PAH input and
emissions of PAH. The PAH emission in the
exhaust consists of uncombusted through fuelinput PAH and PAH formed in the combustionprocess. By selection of diesel fuel quality withlow PAH contents (>_ 4 mg/l, sum of PAH) the
PAH exhaust emissions will be reduced by up toapproximately 80% compared to diesel fuel withPAH contents larger than 1 g/l (sum of PAH).By reducing fuel PAH contents in commercialavailable diesel fuel the emissions of PAH to theenvironment will be reduced.13
Other properties
Other fuel properties may also have an effect onemissions. Fuel density, for instance, may affectthe mass of fuel injected into the combustionchamber, and thus the air/fuel ratio. This is
because fuel injection pumps meter fuel by vol-ume, not by mass, and the denser fuel contains agreater mass in the same volume. Fuel viscositycan also affect the fuel injection characteristics,and thus the mixing rate. The corrosiveness,cleanliness, and lubricating properties of the fuelcan all affect the service life of the fuel injectionequipment; possibly contributing to excessivein-use emissions if the equipment is worn outprematurely.
To the extent that the long term vehicle emis-
sions standards strategy is to adopt European step4 (so-called Euro 4) standards for light dutyvehicles and step 5 (so-called Euro 5) standardsfor heavy duty vehicles, the European diesel fuelstandards as summarized in Table 4 should beadopted in the same timeframe.
Diesel FuelParameter
2000
(Linked
with Euro3 vehicle
Standards)
2005
(Linked
with Euro4 vehicle
Standards)
Cetane number(min.)
51 51
Density(15C kg/m3, max.)
845 845
Distillation(95%, v/v C, max.)
360 360
Polyaromatics(%v/v, max.)
11 11
Sulfur
(ppm, max.) 350 50
Table 4: European Union fuel
specication limits.
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
5.5 Fuel Additives
Several generic types of diesel fuel additives canhave a signicant effect on emissions. Theseinclude Cetane enhancers, smoke suppressants,
and detergent additives. In addition, someadditive research has been directed specically atemissions reduction in recent years.
Cetane enhancers are used to enhance theself-ignition qualities of diesel fuel. These com-pounds (usually organic nitrates) are generallyadded to reduce the adverse impact of higharomatic fuels on cold starting and combustionnoise. These compounds also appear to reducethe aromatic hydrocarbons adverse impacts onHC and PM emissions, although PM emis-
sions with the Cetane improver are generallystill somewhat higher than those from a higherquality fuel able to attain the same Cetane rating
without the additive.
The use of detergent additives
to reduce deposits on injector
components is highly recommended,
especially on more modern engines
Smoke suppressing additives are organic com-pounds of calcium, barium, or (sometimes)magnesium. Added to diesel fuel, these com-pounds inhibit soot formation during the com-bustion process, and thus greatly reduce emis-sions of visible smoke. However, they tend tosignicantly increase the number of very smallultrane particles that are suspected of beingeven more hazardous to health. Their effects onthe particulate SOF are not fully documented,but one study has shown a signicant increase in
the PAH content and mutagenicity of the SOFwith a barium additive. Particulate sulfate emis-sions are greatly increased with these additives,since all of them readily form stable solid metalsulfates, which are emitted in the exhaust. Theoverall effect of reducing soot and increasingmetal sulfate emissions may be either an increaseor decrease in the total particulate mass, depend-ing on the soot emissions level at the beginningand the amount of additive used.
While smoke suppressing additives may appear
attractive, their use is not recommended because
of the potentially more hazardous emissions ofultrane particles and mutagenicity.
Detergent additives (often packaged in combi-nation with a Cetane enhancer) help to prevent
and remove coke deposits on fuel injectortips and other vulnerable locations. By thusmaintaining new engine injection and mix-ing characteristics, these deposits can help todecrease in-use PM and HC emissions. A studyfor the California Air Resources Board estimatedthe increase in PM emissions due to fuel injectorproblems from trucks in use as being more than50% of new-vehicle emissions levels. A signi-cant fraction of this excess is unquestionably dueto fuel injector deposits. The use of detergent
additives to reduce deposits on injector com-ponents is highly recommended, especially onmore modern engines.
Environmentally-friendly cars?
The Environment and Transport Working Party
of Germanys Standing Conference of Environment
Ministers formulated requirements for ecologically
acceptable cars (Table 5).
For the purposes of the present module, an
ecologically acceptable car is a family car equipped
with the best existing technology to mitigate en-
vironmental impacts without sacrificing safety,
comfort and convenience. It provides the following
environmental benets:
Low fuel consumption
Low pollutant and noise emissions
Environmentally sound manufacturing
Lightweight and compact design ensuring
optimum use of materials and recyclability
Environmentally relevant extras.
The resolutions adopted were published in
UBA (1999c). The vehicle type largely satisfies
the requirements for an ecologically acceptablepassenger car.
Manufacturers have already announced their
plans for series-production cars with internal
combustion engines and a fuel consumption of
3 liters per 100 km (78.4 miles per gallon). These
vehicles are to be sold at affordable prices and
satisfy requirements for everyday use, providing
space for 4 to 5 adults and incorporating the
convenience, comfort and safety standards of a
medium-sized car.
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Module 4a: Cleaner Fuels and Vehicle Technologies
Table 5: Proposal by the Standing Conference of Environment Ministers
for phased introduction of ecologically acceptable passenger cars.
6. Alternative fuels
In addition to conventional fuels, gasoline and
diesel fuel, many countries around the worldhave identied signicant benets associatedwith a shift to alternative fuels, especially com-pressed natural gas (CNG), liqueed petroleumgas (LPG or propane) and ethanol.
Alternative fuels include compressed naturalgas (mainly composed of methane), methanol,ethanol, hydrogen, electricity, vegetable oils(including biodiesel), liqueed petroleum gas(composed of propane or butane), syntheticliquid fuels derived from coal and various fuel
blends, such as gasohol.
6.1 Natural Gas (NG)
Natural gas (85 to 99 percent methane) is cleanburning, cheap and abundant in many parts ofthe world. Because natural gas is mostly meth-ane, natural gas vehicles (NGVs) have muchlower non-methane hydrocarbon emissions thangasoline vehicles, but higher emissions of meth-ane. Since the fuel system is sealed, there are noevapourative emissions and refueling emissions
are negligible. Cold-start emissions from NGVs
are also low, since cold-start enrichment is notrequired. In addition, this reduces both VOCand CO emissions. NOx emissions from un-controlled NGVs may be higher or lower than
comparable gasoline vehicles, depending onthe engine technology, but are typically slightlylower. Light-duty NGVs equipped with modernelectronic fuel control systems and three-waycatalytic converters have achieved NOx emis-sions more than 75 percent below the stringentCalifornia Ultra Low-Emission Vehicle (ULEV)standards.
As a substitute for diesel, NGVs should havesomewhat lower NOx and substantially lowerPM emissions unless the diesel vehicle is burn-ing ULSD and is equipped with a PM lter.
Given equal energy efciency, GHG emissionsfrom NGVs will be approximately 15 percentto 20 percent lower than from gasoline vehicles,since natural gas has lower carbon content perunit of energy than gasoline. NGVs have aboutthe same GHGs as diesel fuel vehicles. For theuse of NG which would otherwise be aredin the renery or wasted, the greenhouse gasreduction can be up to 100 % in comparison
with using any other fossil-based fuel, such asgasoline or diesel, which can thereby be saved.
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
Comparing different emissionstandards
Californian emission standards are known to
be the most stringent in the world. Since newtypes of vehicle have been introduced and ad-
vanced mainly in response not to European, but
to Californian legislation, we must consider the
major differences.
While the reduction of direct emissions laid
down in EURO 4 (see margin note) for petrol-engine
vehicles will be sufcient to satisfy the requisite air
quality objectives in Germany and further cuts in
direct exhaust gas emissions from such vehicles
will therefore not be necessary in Germany in the
foreseeable future, the limits for diesel-powered
cars in Europe will be well above those for theirpetrol-engine counterparts, even well into this
millennium. The following comparisons therefore
address only the European requirements for petrol-
engine cars incorporating the best available low
emission techniques.
Californian clean air legislation is rather different.
It does not propose any across-the-board standards
for all new vehicles from a specic date, but various
limits to be introduced step by step with a declining
eet average year by year. Manufacturers are re-
quired to comply with a fleet average for non-
methane organic gases (NMOG).
URO 4
e European step 4 stand-
d, or so-called EURO 4, is
e emission standard set
t in Directive 98/69/EC of
e European Parliament and
the Council of 13 October
98 relating to measures
be taken against air pol-
ion by emissions from
otor vehicles. It will apply
m January 2005. The full
xt of the preamble and the
andard can be downloaded
http://europa.eu.int/eur-
x/en/consleg/main/1998/
_1998L0069_index.html.
urther information on
atural gas vehicles
ease refer to Module 4d:
tural Gas Vehicles for a
ore detailed discussion of
actical aspects related to
tural gas vehicle applica-
ns. NG applications for
ree-wheelers are discussed
Module 4c: Two- and Three-
heelers.
EU and Californian limit values
adusted to the FTP75 ccle foretrol cars /km
0.00
0.05
0.10
0,15
0.20
0.25
0.30
0.35
0.40
TLEV LEV ULEV SULEV EURO 3
(Petrol)
EURO 4
(Petrol)
[g/km]
NMOG
HC
NOx
- LEV II Standards (12/97)- NMOG for California- HC for Europe- NMOG : HC ratio = 1 : 1.25
- 1 mile = 1.6214 km- EURO 3 and EURO 4 based on
modified NEDC.
TLEV Transitional Low Emission Vehicle
LEV Low Emission Vehicle SULEV Super Ultra Low Emission Vehicle
ULEV Ultra Low Emission Vehicle ZEV Zero Emission Vehicle
LEV I LEV I
All fiures for FTP75 c cle
Le islation
Fig. 3
Comparisonof emission limitsfor petrol engine
cars, between Europe
and LEV II,California.
The comparison of emission limits adjusted
to the US FTP75 cycle indicates that the EURO 4
standard for petrol-engine cars is comparable with
the ULEV (Ultra Low Emission Vehicle) standard
in the proposed LEV I legislation (Figure 3). Thegraph also shows that the currently valid LEV and
ULEV limits for NOx
(see Figure 3: [LEV I]) permit
emission levels more than four times as high as
those for a EURO 4 vehicle. The LEV II legislation
therefore tightened NOxand particulate limits and is
substantially more stringent than Euro 4. Distinctive
features of LEV II include an in use durability re-
quirement of at least 120,000 miles, expanded OBD
requirements, supplemental FTP standards which
limit emissions under hard acceleration conditions,
very low evaporative HC limits and a requirement
that almost all cars and light commercial vehicles
using petrol of diesel fuel must comply with the
same NOx
and PM limits.
The once familiar demands for certain automotive
technologies, such as Zero Emission Vehicles (ZEVs)
in the form of electric cars, are no longer warranted
by clean air requirements in the transport sector in
the European Union.
Whether zero emissions vehicles or other ad-
vanced technology vehicles will be needed in any
country depends on a careful assessment of the
air quality problem in that country.
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Module 4a: Cleaner Fuels and Vehicle Technologies
in passenger cars can result in a reduction ofuseful space inside the vehicles trunk because ofthe storage tank.
Natural gas engines cause additional capital costs
for the vehicles engine and the storage tanksystem and further cost for the compression ofnatural gas, covering investment, operation andmaintenance of the lling station.
To store natural gas, it has to be compressed to200 bar (2,900 psi) at the lling station. Theconguration of the lling station accordingto the individual demands of the customer isof great importance in minimising costs. Thequality of the natural gas and the pre-pressureof the supply are also important factors. A high
pre-pressure reduces the compression powerrequired and hence the operating costs. The pre-pressure of a lling station inuences the ratioof the specic costs per volume of compressednatural gas.14
The additional costs of NG bus eets were cal-culated in the THERMIE project at 7 % includ-ing all costs for additional staff, lling station,etc.15 Figure 4 shows that the cost premium fornatural gas buses compared with diesel-poweredbuses will decline as this technology gains a
rmer foothold in new markets over the nextdecade (see margin note).
Comparison of the primary energy use for theproduction processes of CNG and petrol showsthat the primary energy consumption for bothfuels is comparable. In its demonstration project
for CNG-usage, UBA the German Federal En-vironmental Agency considered a scenario of10 % NG heavy duty vehicles in Germany andcalculated a slight increase of equivalent green-house gas emissions of +0.07 %. Clearly the useof NG in heavy duty vehicles will not result in asignicant increase of greenhouse gases.
Furthermore the noise emission of NG busesis in the order of 3 to 5 dB(A) lower, while thesubjective annoyance is much lower, because thegas engine runs much more smoothly.
Obstacles to the widespread use of NGVs in-clude the absence of transportation and storageinfrastructure, cost, loss of cargo space, increasedrefueling time, and lower driving range.
Refueling and storage of the gas must be care-fully considered to meet operational and safetyrequirements. For storing compressed naturalgas at 200-bar pressure, a large tank is needed.The kind of heavy duty vehicle for which theuse of natural gas has the most advantages is theurban bus where the tank is usually installed on
the roof. But heavy duty vehicles have also beentted with under oor installations. Using CNG
Selling price trend for standard service buses incorporating natural
gas propulsion and requsite exhaust gas aftertreatment
100%
105%
110%
115%
120%
1995 1997 1999 2001 2003 2005 2007Year
Price compared
with todays diesel
NG bus
3-4%
Euro 4
Diesel bus
with articulate filter
and SCR
Euro 5Euro 3
100% = price of todays diesel busescomparison:
target price for -
fuel-cell buses +35,800Euro
Fig. 4
Selling priceof natural gasbuses comparedto current diesel
buses.
Cost differentials
between CNG and
standard buses
The cost premium in Europe
in the year 2000 for heavy-
duty vehicles with a natural
gas engine and a CNG tank
was between 20,500 and
35,800 . This amounts to
between 8% and 16% of
the selling price of a stand-
ard service bus. In 2002 the
cost differential was already
reduced to 25,000 . In the
longer term, it will be possible
to reduce the cost premium
for natural gas buses as this
technology gains a rmerfoothold in new markets.
In several major develop-
ing country markets locally
manufactured regular and
CNG buses are available at
a much lower cost than in
Europe. New diesel buses
complying with Euro II emis-
sion standards reportedly are
available for less than 50,000
in China and India, both of
which also manufacture CNG
buses for the domestic mar-
ket at a substantially lower
cost than in Europe.
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
To smooth the way for gas power technologyinto series production through eet testing andverication of tness for use under practicalconditions, the German Federal Ministry of the
Environment, Nature Conservation and NuclearSafety and the UBA take promotional measuresin the form of investment projects providing forconsiderable grants to be paid out to operatorsof new NG vehicles to compensate them for theextra cost they incur compared to diesel fuelledvehicles.16 In Germany, about 80 natural gas ll-ing stations are currently available. NG vehiclesare therefore operated mainly in eets that arebased close to lling stations.
In connection with the above-mentioned invest-
ment project Model operation of NG vehicles,the UBA drew up a list based on informationprovided by the manufacturers. This list showsthe NG Vehicles available in all categories,
which satisfy the emission requirements for thevehicles taking part (Table 5).
6.2 Liqueed Petroleum Gas (LPG)
Engine technology for LPG vehicles is verysimilar to that for natural gas vehicles. As a fuelfor spark-ignition engines, it has many of the
same advantages as natural gas, with the addi-
tional advantage of being easier to carry aboardthe vehicle.
LPG has many of the same emissions character-istics as natural gas. The fact that it is primarily
propane (or a propane/butane mixture) ratherthan methane affects the composition of ex-haust VOC emissions and their photochemicalreactivity, and its global warming potential butotherwise the two fuels are similar.
Using LPG in transport instead of burning it asa waste gas at the oil elds or in the renery willimmediately result in fossil fuel savings. The useof LPG results in an energy efciency for theenergy chain of exploitation, renery and use,comparable to that of gasoline and diesel.
The emissions during use of LPG in the vehi-cles are comparable to the emissions of petrolengines. In the Netherlands, in-use compliancetests were conducted for LPG passenger cars(Rijkeboer, Binkhorst, 1998). The conclusionfrom these tests was that the maintenance situa-tion for the vehicles tested was in fact very good.LPG vehicles easily complied with the currentemission limits. The engine technologies arealready in their third generation, described inthe in-use compliance program as follows:
New Vehicles Retrotted
CarsLight-duty
vehiclesTrucks Buses Cars
Light-dutyvehicles
Manufacturers 6 5 5 3 2 1
Types 18 15 9 7 13 6
Rated powerin kW
44 95 44 105 75 175 140 228 44 85 51 95
Maximumpermissible weightin tons
1.4 2.8 1.6 3.5 4.3 26 11.5 28 1.4 2.0 2.8 3.5
Mixture formation:lambda = 1Lean burn
18-
15-
72
34
13-
6-
Operation:monovalentbivalentoptional
1512
1113
9--
7--
4-9
4-2
Extra costsin US$ thousands 1.3 5.4 3.2 7.3 5.5 51.0 38.8 52.0 3.1 6.9 3.3 3.6
Table 5: Overview of NG vehicles available which meet the requirements of the
investment project Model Operation Of NG Vehicles (2/1998).
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Module 4a: Cleaner Fuels and Vehicle Technologies
a) 1st generation:
Mechanical system with mechanical controlof the metering; no closed loop.
b) 2nd generation (analogue):
Mechanical system with mechanical control.Additional closed loop control by means ofa lambda sensor. This closed-loop control
works relatively slowly.
c) 2nd generation (digital):
System whereby the ow takes place aspreviously via the venturi, but whereby themetering is regulated by a microprocessor
with pre-programmed engine maps. Closedloop control is also by means of a lambdasensor. The control can be more accurate, but
the closed-loop is still relatively slow.d) 3rd generation:
This system distinguishes itself from the 2ndgeneration in that it is a self-adaptive system.Observed deviations in the air/fuel ratio arestored in the memory and processed in thedigital control metering. In practice these areoften multi-point injections.
The emissions of the different generations ofLPG systems are given in the Figure 5.
The emissions of LPG in heavy duty vehicle
engines are far below the emission standards forEURO 3 heavy duty vehicles, which are imple-mented in Europe for the year 2000.18
The heavy duty vehicle was equipped with aclosed-loop fuel system and a 3-way catalyst.The 6 cylinders, 135 kW engine with stoichio-metric mixture and natural aspiration has a
compression ratio of 10:1. The maximum en-
0,00
0,10
0,20
0,30
0,40
0,50
0,60
0,70
0,80
0,90
CO HC NOx
[g/km]
__
2nd__
Generation
__
3rd__
Generation
__
2nd__
Generation
__
2nd__
Generation
__
3rd__
Generation
__
3rd__
Generation
__
best__
vehicletype
1,72
20
vehicles
3
vehicles
18
vehicles
Passenger Cars with different
LPG-generation systems
__
best__
vehicletype
__
best__
vehicletype
Fig. 5
Emissions of dedicatedLPG vehicles in the newEuropean Driving Cycle(NEDC).Rijkeboer, Binkhorst 1998
g/kWh HC CO NOx
PM
LPG 0.5 1.8 0.5 -
Emission Limits for Diesel Engines
EURO 1 1992 1.25 5 9 0.4
EURO 2 1996 1.1 4 7 0.15
EURO 3 2000 0.6 2 5 0.1
Table 6: Emissions in the 13-Mode Test
for a 7.4 litre LPG engine running with
aged catalyst (lamba = 1).
gine efciency is high, ranging from 33 to 37%at full load. Over the 13-mode test, the engineshows favourable emission values with an agedcatalyst (30,000 km) as summarized in Table 6.
With a more sophisticated fuel system (forexample, electronically controlled fuel injection)there is potential for further emission reductions.
The costs of converting from gasoline to propane
are considerably less than conversions to naturalgas, due primarily to the lower cost of the fueltanks. As with natural gas, the cost of conversion
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Module 4a: Cleaner Fuels and Vehicle Technologies
In engines burning reformulated gasoline usingethanol, VOCs and CO are reduced but NO
x
tends to increase slightly.
Vehicles burning gasohol will emit slightly more
GHG emissions than conventional gasolinefuelled vehicles. Reductions associated withburning pure ethanol depend on the feedstock.Ethanol produced from corn has life cycle GHGemissions about 15 percent less than gasolinevehicles. Ethanol produced from woody biomass(E-100) has GHG emissions 60 to 75 percentbelow conventional gasoline.
A gasohol-fuelled automobile costs no morethan a comparable gasoline vehicle. Since etha-nol is derived from grains and sugars, the pro-
duction of ethanol for fuel is in direct competi-tion with food production in most countries.This keeps ethanol prices relatively high, whichhas effectively ruled out its use as a motor fuelexcept where, such as in Brazil and the U.S., it isheavily subsidised.
The Brazilian Prooalcool program (Figure 6)to promote the use of fuel ethanol in motorvehicles has attracted worldwide attention as asuccessful alternative fuel program. Despite theavailability of a large and inexpensive biomass
resource, however, this program still depends onmassive government subsidies for its viability.
The high cost of producing ethanol (comparedto hydrocarbon fuels) remains the primary bar-rier to widespread use.
6.5 Biodiesel
Biodiesel is produced by reacting vegetable oranimal fats with methanol or ethanol to producea lower-viscosity fuel that is similar in physical
characteristics to diesel, and which can be usedneat or blended with petroleum diesel in a dieselengine.
Over the years, many factors have stimulatedinterest in biofuels including biodiesel. Forexample, the primary initial motivation for theBrazilian Alcohol program was energy relatedconcerns. However, it seems that the greatestmotivation today for increased interest in bio-mass-based fuels in many countries is concernover the environment, especially with urban airpollution and global warming. Further, there is
Fig. 6
A range of cleaner fuels,both conventional andalternative, are availablein Curitiba, Brazil.Karl Fjellstrom, Feb. 2002
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
energy, which means that it has to be producedfrom other fossil or non-fossil energy sources.
It is often proposed to use hydrogen in roadtransport instead of carbon-containing gases, to
provide a CO2 advantage. Evaluating the totalfuel life cycle, however, shows that using otherfossil primary energy for the production of H
2
does not result in a net CO2
advantage. Hydro-gen as a fuel for road applications will be mostadvantageous when it is produced with renew-able resources, such as electricity from renewableenergy or from biomass.
Hydrogen can be used in internal combustion(IC) engines or fuel cells. If hydrogen is usedin a heavy duty IC engine, emissions of CNG
engines are comparable to hydrogen enginesfor NO
x, and for low PM exhaust emissions.
Data for IC engines of passengers cars is not yetavailable. Instead of using a combustion engine,research efforts are focusing on the use of hydro-gen in fuel cells in vehicles, which can be moreefcient than using methanol in a fuel cell.
The total fuel life cycle shows that
using other fossil primary energy
for the production of H2does notresult in a net CO2
advantage
Costs, other restrictions
Hydrogen from renewable sources will have ad-ditional costs in comparison to the costs neededto generate renewable electricity. One studycarried out in 1997 concluded that the energycontent of gaseous hydrogen is reduced to 65 %of the solar production electricity. In addition,the costs including transport were found to be
twice the costs of the solar electricity at thattime. Using liqueed hydrogen resulted ina 50 % reduction of the solar electricity andresulted in costs more than four times higherthan costs of solar electricity.21
6.7 Electric Vehicles
A comprehensive eld test study about ElectricVehicles (EVs) was made with about 60 vehicleson the German Baltic island Rgen in 1996.The German IFEU - Institute for Energy andEnvironmental Research, Heidelberg, performed
growing interest in providing a protable marketfor excess farm production.
Biodiesel is a zero sulfur diesel fuel. Thereforemany of the points noted above, especially with
regard to the potential impact on advanceddiesel control technologies, apply equally tobiodiesel.
In general, biodiesel will soften and degradecertain types of elastomers and natural rubbercompounds over time. Using high percentblends can impact fuel system components(primarily fuel hoses and fuel pump seals) thatcontain elastomer compounds incompatible
with biodiesel. Manufacturers recommend thatnatural or butyl rubbers not be allowed to come
in contact with pure biodiesel as this will leadto degradation of these materials over time,although the effect is lessened with biodieselblends.
The general consensus is that blended or neatbiodiesel has the potential to reduce diesel COemissions (although these are already low),smoke opacity, and measured HC emissions.However, many studies show an increase in NO
x
emissions for biodiesel fuel when compared todiesel fuel at normal engine conditions. While
research shows a reduction in HC emissionswhen biodiesel is used, the effect of the organicacids and/or oxygenated compounds foundin biodiesel may be affecting the response ofthe instrument that measures HC, the ameionization detector, thus understating the actualHC emissions. Particulate data are mixed.Most studies show a reduction but some showincreases under certain conditions. For example,one study found that:
Biodiesel gave generally higher particulateemissions and the highest levels of particulateassociated soluble organic fraction for all drivingcycles.20
The high cost of biodiesel fuel is one of theprincipal barriers making it less attractive tosubstitute for diesel fuel.
6.6 Hydrogen (H2)
Hydrogen is usually used as compressed hydro-gen (CH
2
) with 200 bar or liqueed hydrogen(LH
2) at -252C (422F). Hydrogen is a secondary
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Module 4a: Cleaner Fuels and Vehicle Technologies
the comparative eco-balance. The following pas-sages are a short summary from Daug (1996).
Greenhouse gases, other emissions
Energy consumption and emissions of the ve-hicles depend on a large number of parameters.The most important of these energy consump-tion parameters are the driving energy, thebattery consumption (internal resistance con-sumption, battery heating, recharging energy,efciency of charging, self-discharge), the second-ary energy consumption (charging converter) andthe additional heating.
The comparison of electric motorcars withconventional cars are highly dependent on the
electricity generation in each country, and var-ies substantially even within the same country.For example, in 2005 more than 50 % of theelectricity in Germany will be generated by coalpower plants and around 5 % of the electricity
will be renewable. In Brazil, on the other hand,a large fraction of the electricity is from renew-able hydropower.
The advantages of the electric motorcar overthe conventional car include that the electriccar does not generate emissions which are toxic
to humans and which damage physical assetsdirectly at the site of deployment. The electriccars generate less noise and contribute to a lesserdegree to summer smog and nitrogen inputinto soils and water bodies depending on thesource of the electricity. The disadvantages ofthe electric motorcar include that it could havea higher acidication potential and a strongerclimatic impact if the electricity is generated forexample from coal burning. These disadvantagescan increase with decreasing daily kilometreperformance and can only be compensatedunder special conditions of deployment such asvery frequent short distance drives.
Costs, other restrictions
In the UBAs view, the EV has to be comparedwith the best available technology of internalcombustion engines. Because of the EVs ad-vantage of local zero emissions, the comparisonsare made between the additional costs of anEV dominated by the battery costs andthe additional costs for an Ultra Low Emission
Vehicle (ULEV-) standard, in comparison to the
then (1996) current TIER I emission standardvehicle.
The additional incremental cost of an ULEVwas estimated to be between US$84 and
US$200, depending on the size of the engine(Carb, 1996). The incremental costs were esti-mated to be 2.7 to 5.3 cents/mile for the batterydepending on the type and specic costs of thebattery. UBA calculated from these data costs ofUS$2,700 to $6,400 for the additional incre-mental lifetime cost of the battery for an EV atthat time (Kolke, 1995).
It was concluded by UBA that on the basis of aTIER I vehicle, the additional incremental costof only one electric vehicle could nance the
additional incremental costs of up to 75 ULEVvehicles. From the urban environmental pointof view, the cost effectiveness of a completeintroduction of a ULEV standard for all vehicles
was estimated to be higher than having some10 % of EVs, 15 % of ULEV and 75 % ofTransitional-Low-Emission Vehicle (TLEV).
The use of EVs makes sense in ecologicallysensitive areas or enclosed indoor facilities thathave a proven need for zero local emissions. Intypical trafc situations, based on UBAs 1996
study, it may be more cost effective to introducestringent emission limits, such as the ULEVstandard or the EURO 4 standard for petrolvehicles.
On the basis of a TIER I vehicle,
the additional incremental cost
of only one electric vehicle could
nance the additional incremental
costs of up to 75 ULEV vehicles
6.8 Fuel Cells
Fuel cell (FC) vehicles are currently being dis-cussed as one of the most promising technolo-gies for the future. Hydrogen, methanol andeven petrol are discussed as fuels for the vehicles.Further differentiation must be done for thevarious possibilities of producing the fuel.
In the UBAs view, the rst step of a Research
and Development program must be the detailedand realistic estimation of the environmental
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Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities
effects and the costs for the applications, incomparison to the best available conventionaltechnology. Only if a transparent analysis showsa cost competitiveness of fuel cells, assuming
that they reach a sustainable emission reduction,should the fuel cell application be considereda realistic alternative technological solution forreducing emissions in the road transport sector.
Greenhouse gases, other emissions
The efciency of the fuel cell vehicle and theircosts will be one of the main problems on its
way to becoming the car of the future. TheUBA did investigations for different cars of thefuture, based on its assumptions of likely devel-opments. The comparisons were made relative
to a competitive fuel-efcient vehicle with apetrol engine, which is available as a prototype;the SMILE Concept developed with assistancefrom Greenpeace (1996). This car has room forfour passengers, a curb weight of 650 kg, a fuelconsumption of 3.25 liters per 100km (72 mpg)and can reach ULEV emission levels. The calcu-lations of the incremental costs were made forthe efcient ULEV with a 40 kW engine andfor a fuel cell vehicle with a mechanical power of15 kW, a nominal engine power of about 18 kW
(peak about 32 kW) and a fuel cell power of40 kW. Two types of vehicle were examined:
The fuel cell vehicle with compressedhydrogen storage,The fuel cell vehicle with methanol andreformer.
The calculations showed that the weight for thestorage system and the propulsion components(engine, fuel cell, reformer, etc.) will be between2 and 3 times higher than for the petrol fuelledcar of the future.
The main current advantage of the fuel cellvehicle is the very low emissions. The UBAcalculated the emissions of the efcient ULEVand the fuel cell vehicles under consideration ofthe emissions for fuel production, and comparedthem to a 1996 EURO 2 petrol vehicle (fuelconsumption 6 liters per 100km or 39 mpg).The fuel consumption data for the fuel cellvehicles were given by Daimler (1997) with20 kWh/100km and 26 kWh/100km (hydro-gen, methanol) for a 730 kg vehicle.
The efcient ULEV gives already noticeableemission reductions of about 50 %, up to85 %. The reduction of the direct emissions issufcient for achieving the air quality targets
in Germany. A further reduction of the directemissions will not be necessary in Germany ifall vehicles comply with this or a comparableemission standard. Comparing the directly andindirectly caused emissions, the fuel cell vehicles
with very optimistic fuel consumption data canreduce emissions further in all cases.
The main rating parameter will be given by therelation of the additional costs for the new tech-nologies to the benet, which is the reduction ofemissions and primary energy use in comparison
to a vehicle achieving EURO 2 with 39 milesper gallon). These parameters will describe thespecic emission avoidance costs. A summary ofthe additional calculations is given in the follow-ing section.
Costs, other restrictions
To calculate the emission avoidance costs forpassenger cars in comparison to a EURO 2standard vehicle, the emission reductions arecompared to the extra vehicle costs. The extravehicle costs are composed of various cost com-
ponents, which contain for the most part thedrives and storage costs, as well as energy costsfor operation. The determination of the extracosts for the drives is carried out on the basis ofan analysis and calculation of the specic costs.Figure 7 shows the basis of the calculation of thecost distribution with fuel cell costs of 50 /kW.Further calculations are summarized following.
As in the long term the most important con-sideration will be the reduction of greenhouse-relevant CO
2
emissions, the following resultssummarize the calculations for the reductionof greenhouse gases. UBA also took the furtherUS target data for fuel cell technology intoaccount, which are characterised by the costspublished in the Ford/DOE program and sum-marized in Sims (1997), with US$1824/kWmanufacturing costs for the FC-stack. Anothercalculation was made with the development goalof US$50/kW for an implementation strategyfor the whole FC propulsion drive.
Even assuming the successful development offuel cell technology for transport (US$50 /
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Module 4a: Cleaner Fuels and Vehicle Technologies
0 DM
4.000 DM
8.000 DM
12.000 DM
16.000 DM
EURO 2
1996
Efficient
ULEV
Fuel Cell
Methanol
Fuel Cell - H2
Natural Gas
Fuel Cell - H2
Hydro & Wind
Costs[DM/life]
Costs of Energy
Costs of PropulsionDrive and Storage
(2,200 US$)
(8,800 US$)
(6,600 US$)
(4,400 US$)
Fig. 7
Ratio of distributionof costs of new passengercar concepts with a
lifetime of 10 years.
kWFC Drive Line), the costs for emissionsavoidance of the greenhouse gas CO
2can rise up
to US$200 per metric ton. The avoidance costsare at least US$83 per metric ton of CO
2more
than the avoidance costs of an efcient vehicle
with an internal combustion petrol engine andultra low emissions.
The UBA made further comparisons of the costsand the possible emission reductions of fuel cellbuses to be driven with hydrogen, and buses
with internal combustion engine and naturalgas (NG). While the rst system can reduce thecritical emission components of NO
xand par-
ticulate matter (PM) completely in comparisonto a diesel bus, the natural gas bus can reduceNO
xby 85 % and PM by more than 99 %. The
cost comparison shows that fuel cell technologyis not a cost competitive technology for publicbuses in the near future, perhaps for the next 20years.
The avoidance costs are at least
US$83 per metric ton of CO2
more than the avoidance costs of
an efcient vehicle with internal
combustion petrol engine and
ultra low emissions
As there is no real data for the future costs of FCbuses available, the comparison has to be madeon the basis of the best available competitivetechnology, which is the NG bus. The produc-tion-ready and available NG technology has
additional costs of US$22,00039,000 whichcan be reduced to US$14,000 in the next 10years (see margin note).
Nevertheless, fuel cell technology is a promisingfuture technology. But a differentiated look atthe use of fuel cells is required from an environ-mental point of view, according to the energyservices that they are going to provide and theavailable or foreseeable alternatives in each case.The FC use in the stationary area appears tobe sensible and capable of development, since
they can already convert fossil energy sources(e.g. natural gas) into electricity and heat or becoupled with cooling production much moreefciently than previous power plants or heatproducers.
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Sustainable Urban Transport: A Sourcebook for Policy-makers in Developing Cities
Retrot policies andexperiences in GermanySource: Axel Friedrich, German Federal Environmental Agency
Note: 1 DM is approximately 0.5
The retrot of in-use vehicles (Figure A) is one of
the major instruments available to reduce emissions
from the transport sector in a short time frame. In
spite of this fact, most attempts made in different
parts of the world have not been very successful.
In Germany a high environmental consciousness
caused by reports on the forest dying and other
harmful effects of air pollution lead to ambitious
legislation to reduce emissions from industry
and transport. In the early 1980s the retrot of
power plants with scrubbers and catalysts for the
reduction of sulfur dioxide and nitrogen oxides (NOx)
were required. After the introduction of three-way
catalysts in the mid-1980s, there were calls for
retrotting gasoline cars with open loop three-way
catalysts or exhaust gas recirculation (EGR). The
open loop three-way catalyst reduces the emissions
of a gasoline car with carburetor by about 50%. The
retrotted EGR reduces the NOxby about 30% within
the lower speed range where the NOxemissions are
lower. This retrot program was supported by tax
incentives. The devices had to have a type approval
for each vehicle family. Because of the loophole
that no durability requirement was established,
inadequate systems were also used.In the second phase, in addition to the open loop
three-way catalysts, emission limits, which require
the installation of three-way catalysts with lambda
control, were included in the legislation. The retrot
kits which are able to meet the Euro I car emission
standards were not required to pay the annual car
tax until the total amount reached 1250, - DM (about
US$650) and af terwards the owner had to pay the
reduced annual tax fee for a Euro I car. The legal
requirement included the same procedure for type
approval as for new cars. After the installation, each
individual car had to be checked by licensed test
centres and a change of the vehicle identication
card had to be made by the authorities. Due to this
legal requirement the industry developed retrot
kits which met the Euro I standards and the retrot
costs for a middle-size car came down to about
1250, - DM (around 640 ).
The retrot kit includes the three-way catalyst
(including the tubing made in stainless steel), the
electronic control unit including the lambda sensor,
as well as the parts for the introduction of additional
air below the carburetor and if necessary an adapter
for the carburetor. The certication documents
were added. The garages got a calibration unit for
0
5
10
15
20
25
30
CO
HC+NOx
CO
HC+NOx
CO
HC+NOx
CO
HC+NOx
CO
HC+NOx
CO
HC+NOx
emissions/(g/km)
with Kat 2000
w/o Kat 2000
VW Kfer Ford Fiesta Fiat Uno Opel Kadett Jaguar XJ 12 VW Golf
1,6 l, 36kW 1 l, 33kW 1 l, 32kW 1,3 l, 44kW 5,3 l, 134kW 1,6 l, 55kW
CO and (HC + NOx) emissions
0
0,5
1
1,5
2
2,5
3
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
(HC + NOx) [g/km]
CO[g/km]
injection
carburettor
EURO I emission standard
EURO II emission standard
B
C
Retrofit systems are available for:
Gasoline cars (closed loop threeway catalysts )
Motorcycles ( oxidation catalyst for two strokeengines and smaller 4 stroke engines, closed
looped threeway catalysts for bigger 4 stroke
motorcycles )
Busses and trucks ( particles filters , NG and
LPG with closed loop threeway catalysts )
Diesel cars and LDT (particle filters, soon
available) A
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Module 4a: Cleaner Fuels and Vehicle Technologies
the correct setting of the engine and the lambda
value.
In Figure B, the emissions before and afterretrot are shown for some vehicles of different
size and age. One of the oldest vehicles retrotted
is the Fiat Topolino from the model year 1936! The
conversion achieved emission reductions in the
range of 90%.
In Figure C, the type approval data from many
different vehicles are shown. It can be seen that a
considerable number of vehicles also meet the Euro
II standards for all three pollutants.
In the year 1998 the annual vehicle tax was
changed in order to reect the emission