4a Cleaner Fuels and Vehicle Technologies

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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


6.8 Fuel cells 19

Greenhouse gases, other emissions 19


7. Conclusions 24

Further information 25

Endnotes 25

Other references 26

Recommended Websites 27Some common abbreviations 27


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1

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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2

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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3


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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4


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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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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6


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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7


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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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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9


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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10


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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11


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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12


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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13


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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14


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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15


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


20/32


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17


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


22/32

18


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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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.


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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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.


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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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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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

Documents

4a Cleaner Fuels and Vehicle Technologies