Policy Guidelines for Reducing Vehicle Emissions in Asia. Cleaner Fuels

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2 Policy Guidelines for Reducing Vehicle Emissions in Asia Cleaner Fuels

3 Asian Development Bank 2003 All rights reserved This publication was prepared by staff of the Asian Development Bank. The findings, interpretations, and conclusions expressed in it do not necessarily represent the views of ADB or those of its member governments. ADB does not guarantee the accuracy of the data included in this publication and accepts no responsibility whatsoever for any consequences of their use. The term country does not imply any judgment by ADB as to the legal or other status of any territorial entity. Publication Stock No Published by the Asian Development Bank P.O. Box 789, 0980 Manila, Philippines

4 Contents Preface Abbreviations Executive summary iv vi vii Introduction 1 Integrated strategies to reduce vehicle emissions 3 Fuel quality standards 7 Gasoline 8 Lead additives 8 Sulfur 9 Vapor pressure 10 Benzene 11 Oxygenates 11 Other gasoline properties 12 Diesel fuel 14 Impact on emissions from heavy-duty engines 14 Impact on emissions from light-duty vehicles 15 Sulfur 16 Other diesel fuel properties 19 Fuel additives 22 Alternative fuels 23 Natural gas 23 Liquefied petroleum gas 25 Methanol 26 Ethanol 27 Biodiesel 28 Conclusions regarding alternative fuels 29 Regional cooperation 31 Conclusions 33 Notes 34

5 iv POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Preface Concerned with the increasing levels of air pollution caused by motor vehicles in Asia s major cities, Asian Development Bank initiated a project on Reducing Vehicle Emissions in November The project collected and disseminated information on policies to reduce vehicle emissions through the Reducing Vehicle Emissions in Asia website ( an information portal on international, regional, national and city level experiences in reducing vehicle emissions. Through five workshops, the project provided a venue for the sharing of experiences between countries in Asia and the introduction of best practices on reducing vehicle emissions from other regions Fuel Quality, Alternative Fuels, and Advanced Vehicle Technology held on 2 4 May 2001 in New Delhi, India, Reducing Emissions from Two and Three Wheelers held on 5 7 September 2001 in Hanoi, Viet Nam, Strengthening Vehicle Inspection and Maintenance held on 7 9 November 2001 in Chongqing, PRC, Transport Planning, Demand Management and Air Quality held on February 2002 in Manila, Philippines, and Concluding Workshop on Reducing Vehicle Emissions held on 28 February 1 March 2002 in Manila, Philippines. The project supported the formation of multi-sector action plan groups and the formulation of three action plans Integrated Vehicle Emission Reduction Strategy for Greater Jakarta, Indonesia, Strengthening Vehicle Inspection and Maintenance in Chongqing, People s Republic of China, and Integrated Action Plan to Reduce Vehicle Emissions in Viet Nam. It provided

6 CLEANER FUELS v resources for two studies Study on Air Quality in Jakarta, Indonesia: Future Trends, Health Impacts, Economic Value and Policy Options and Pricing and Infrastructure Costing for Supply and Distribution of CNG and ULSD to the Transport Sector in Mumbai, India. The Policy Guidelines for Reducing Vehicle Emissions in Asia consist of five main books with these titles: Reducing Vehicle Emissions in Asia Cleaner Fuels Cleaner Two and Three Wheelers Vehicle Emissions Standards and Inspection and Maintenance Transport Planning and Traffic Management for Better Air Quality These books come with a common appendix on the Adverse Health and Environmental Effects from Vehicle Emissions printed as a separate book to clearly demonstrate the health and environmental impacts caused by air pollution from vehicles. These policy guidelines, which are based on the five workshops organized by the project, provide an in-depth analysis of the different components of an integrated strategy to reduce pollution from vehicles in Asia. Policymakers in Asia will have to combine the general principles outlined in the policy guidelines with their knowledge of the local situation in their countries and cities to arrive at effective strategies. The Reducing Vehicle Emissions project produced its final report in a CD-ROM containing the workshop presentations, action plans, studies, and policy guidelines.

7 vi POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Abbreviations ADB CNG CO EU GHG HC LPG MTBE NGV NO x PAH PM PPM ULSD SOF SO x SO 2 T 90 T 95 VOC Asian Development Bank compressed natural gas carbon monoxide European Union greenhouse gas hydrocarbon liquefied petroleum gas methyl tertiary-butyl ether natural gas vehicle nitrogen oxides polycyclic aromatic hydrocarbon particulate matter parts per million ultra-low sulfur diesel soluble organic fraction sulfur oxides sulfur dioxide temperature at which 90% of diesel/gasoline evaporates temperature at which 95% of diesel/gasoline evaporates volatile organic compound

8 CLEANER FUELS vii Executive summary As part of its Regional Technical Assistance project to reduce motor vehicle air pollution, Asian Development Bank (ADB) organized a workshop on clean fuels in New Delhi, India on 2 4 May The Cleaner Fuels Policy Guidelines summarize the most important policy conclusions from the workshop regarding the critical role of fuels in determining vehicle emissions. The guidelines focus on (i) improvements that should be made to conventional fuels to reduce their negative impacts and (ii) the increasingly important role that can be played by alternative fuels. In setting fuel quality standards, policymakers should be guided by the following general principles: Implementing a successful systems approach to setting fuel standards requires institutional mechanisms that involve a variety of stakeholders from government, private sector and civil society, and allows for extensive consultation. In countries where such an institutional mechanism is not yet in place, it should be created. Environmental and public health concerns are the driving force behind improvements in fuel quality, thus the Environment Department should have a major role in setting fuel standards. All countries should develop a short- and medium-term strategy that identifies standards to be adopted over the next several years so as to allow fuel providers and the vehicle industry sufficient time to adapt. The main impediment to adopting state-of-the-art new vehicle emissions technology (equivalent to European Step 3 and Step 4, also called Euro 3 and Euro 4) in Asia is fuel

9 viii POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA The addition of lead to gasoline should be fully eliminated in Asia as rapidly as possible quality, especially lead and sulfur levels in gasoline and sulfur levels in diesel. These parameters should receive the highest priority in the development of medium- and longterm strategies for fuel standards. Raising the necessary capital funds is the major issue in investing in refineries to manufacture low-sulfur diesel fuels. In developing fuel standards, countries should attempt to work closely with neighboring countries and harmonize standards where possible. This should not, however, be used as an excuse for delaying or watering down requirements, as harmonization does not mean that all countries must follow the same time frame. In order to implement stricter fuel standards and make associated costs more acceptable to consumers, countries should institute more and better awareness campaigns. Such campaigns must emphasize the public health consequences of not improving fuel quality. Subsidies that favor fuels which produce high emissions, should be eliminated; tax policies which encourage the use of the cleanest fuels, should be adopted. With regard to gasoline, the following policies are recommended: The addition of lead to gasoline should be fully eliminated in Asia as rapidly as possible. In order to maximize the performance of current catalyst technology, gasoline sulfur concentrations should be reduced to a maximum of 500 parts per million (ppm) as soon as new vehicle standards requiring catalysts are introduced. If the longer-term target is 50 ppm or lower, moving directly to this level in one step would reduce the overall cost and should be considered. Emerging advanced catalyst technologies capable of achieving very low emissions will require a maximum of 50 ppm sulfur or less. A plan to introduce such fuel quality should be adopted in the early stages of development of a long-term vehicle pollution control strategy.

10 CLEANER FUELS ix Gasoline vapor pressure should be reduced to a maximum of 60 kilopascals whenever temperatures in excess of 20 C are anticipated. In tropical or semi-tropical countries such as found in much of Asia, this means all the time. Benzene content should be reduced to a maximum of 1% by volume. To the extent that the long-term vehicle emissions standards strategy is to adopt Euro 4 standards for light duty vehicles, the European gasoline standards should be adopted in the same or earlier time frame. With regard to diesel fuel, the following policies are recommended: To introduce European Step 2 (Euro 2) vehicle emissions W standards, the maximum sulfur content should be re- in diesel fuel quality will hile interim improvements duced to 500 ppm; for Euro 3, benefit air quality, the most the maximum should be no more than 350 ppm; for efficient and cost-effective step is Euro 4, 50 ppm is required. for a refinery to go directly to the Maximum emission reductions from Euro 4 or more ad- lowest-desired sulfur level rather than take several interim steps vanced systems will be achieved with a maximum of 10-ppm sulfur. A plan for introducing such low-sulfur fuels should be adopted early in the development of a long-term integrated vehicle pollution control strategy. To the extent that the long-term vehicle emissions standards strategy is to adopt Euro 4 standards for light-duty vehicles and European Step 5 (so called Euro 5) standards for heavy-duty vehicles, the European diesel fuel standards should be adopted in the same or earlier time frame. While interim improvements in diesel fuel quality will benefit air quality, the most efficient and cost-effective step is for a refinery to go directly to the lowest-desired sulfur level rather than take several interim steps.

11 x POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA When low-sulfur diesel fuel is introduced, strong consideration should be given to retrofitting existing vehicles with oxidation catalysts (500 ppm maximum sulfur) or diesel particulate matter (PM) filters (50 ppm maximum) which can achieve significant and rapid PM reductions. An effective way to encourage the rapid introduction of low-sulfur fuels beyond the traditional command-and-control regulations is to adopt a tax policy that results in higher pump costs for higher-sulfur fuels. Hong Kong, China has successfully implemented such a strategy. While less critical, other diesel fuel properties such as cetane number, density, distillation and polyaromatic content can also have positive or negative impacts on emissions and should be carefully evaluated. Considering the current stage of development and emission reduction potentials of alternative fuels, the following policies are recommended: Where compressed natural gas (CNG) is readily available in a given locality, and where very low-sulfur diesel (50 ppm or less) is not readily and reliably available, strong consideration should be given to replacing diesel buses with CNG buses. Other centrally-fuelled fleets such as refuse trucks or local delivery trucks are also attractive candidates for replacement. (As previously noted, where diesel fuel with 50-ppm sulfur or less is available, or mandated to be made available within a reasonable time period of a maximum of 3 years or less, particulate filter retrofits should be considered as a possible lower cost option.) Where CNG or liquefied petroleum gas (LPG) is readily available in a given locality, strong consideration should be given to replacing other high-polluting vehicle types such as 2-stroke engine autorickshaws with CNG or LPG. Conversion to both LPG and CNG has been well established as a viable technology. In terms of PM and hydrocarbon (HC) emission reductions, the most successful strategy for three wheelers is to replace the existing gaso-

12 CLEANER FUELS xi line-fuelled, 2-stroke engine with a CNG- or LPG-fuelled 4-stroke engine. There are several obstacles to the widespread use of CNGand LPG-fuelled vehicles. These include the absence of transportation and storage infrastructure, additional cost primarily of the fuel storage tanks, loss of cargo space, increased refuelling time, and lower driving range. Therefore, economic incentives in the form of lower fuel taxes and others should be considered as a means to stimulate the introduction and acceptance of these fuels. Where LPG is readily available, and where ultra-low sulfur diesel (ULSD) is not readily and reliably available, strong consideration should be given to replacing diesel or petrol taxicabs with LPG. Conversion of existing diesel vehicles to natural gas is difficult and problematic, and very often results in higher nitrogen oxide (NO x ) emissions. Therefore, for diesel vehicles, replacement should be considered rather than conversion. Conversion of existing gasoline-fuelled vehicles to CNG or LPG is not very difficult, and if done well, can result in emission reductions. Conversions should, thus, be considered wherever such fuels are available in a given location, and catalytic converters should be used to gain maximum benefits from switching to CNG or LPG. An inherent advantage of gaseous fuels is the assurance that adulteration will not be a problem. They are also inherently low in PM. These factors should be fully taken into account when considering whether or not to switch vehicles to these fuels.

13 Introduction As part of its Regional Technical Assistance project to reduce motor vehicle air pollution, Asian Development Bank (ADB) organized a workshop on clean fuels in New Delhi, India on 2 4 May The Cleaner Fuels Policy Guidelines summarize the most important policy conclusions from the workshop regarding the critical role of fuels in determining vehicle emissions. The guidelines focus on (i) improvements that should be made to conventional fuels to reduce their negative impacts and (ii) the increasingly important role that can be played by alternative fuels. Motor vehicles emit large quantities of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO x ), and such toxic substances as fine particles and lead. Each of these, along with secondary by-products such as ozone, can cause serious health and environment problems. Growing vehicle populations and high vehicle emission rates have led to serious air pollution, and the resulting health problems have become increasingly common phenomena in modern life. 1 Over the course of the past 30 years, pollution control experts around the world have realized that cleaner fuels must be a critical component of any effective clean air strategy. In recent years, this understanding has strengthened and spread to most regions of the world. Fuel quality is now seen as not only necessary to reduce or eliminate certain pollutants directly (e.g., lead), but also as a precondition for the introduction of many important pollution control technologies (e.g., lead and sulfur). Further, one critical advantage of cleaner fuels has emerged its rapid impact on both new and existing vehicles. For example, tighter new car standards can take ten or more years to be fully effective, whereas lowering lead levels in gasoline reduces lead emissions from all vehicles immediately.

14 Integrated strategies to reduce vehicle emissions In developing strategies to clean up vehicles, there must be a clear understanding of the emission reductions required from all sources to achieve healthy air quality. Depending upon the air quality problem and the vehicle emissions contribution, the degree of control required will differ from location to location. As illustrated in Figure 1, the initial step should be a careful assessment of air quality and the sources that contribute most to the problem or problems. Where vehicles are the major culprits, a broad-based approach will be needed to formulate and implement policies and actions Meteorology Dispersion modeling Ambient concentration Population distribution and activity Exposure assessment Figure 1 Integrated Air Quality Management Framework Emissions Exposure Issues n Technical n Economic n Institutional n Legal n Policy n Social n Stakeholder involvement Emission management n Establish objectives, identify data gaps, studies and pilots n Identify, analyze, and select management options n Develop strategies and implement action plan n Institute monitoring and enforcement Doseresponse Damage assessment Options n Fuels and vehicle technology n Traffic management n Standards n Economic incentives and disincentives

15 4 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Where compressed natural gas (CNG) is readily available in a given locality, and where very low-sulfur diesel (50 ppm or less) is not readily or reliably available, strong consideration should be given to replacing diesel buses with CNG buses aimed at reducing their pollution. The following groups of stakeholders will each have an important role in the development of appropriate policies and strategies: National government agencies; Local government agencies; Industry (including vehicle producers, fuel producers, catalyst suppliers, maintenance industry and others); Intermediate groups which can help advocate for and implement pollution reduction campaigns; End users. Within this group it is important to differentiate between user groups such as rickshaw drivers who depend on the affected vehicles for a living, and users who require vehicles for personal transportation; and Breathers.

16 CLEANER FUELS 5 Effective and efficient coordination mechanisms for vehicle pollution management must be established. These should include the clear allocation of responsibilities for specific functions and tasks to individual agencies and organizations. Inspection and maintenance Emissions standards (technology) Clean fuels Reducing vehicle pollution usually requires a comprehensive strategy. Generally, the goal of a motor vehicle pollution control program is to reduce emissions from in-use motor vehicles to the degree reasonably necessary to achieve healthy air quality as rapidly as possible. Failing that for reasons of impracticality, the goal is to meet the practical limits of effective technological, economic, and social feasibility. A comprehensive strategy to achieve such goals includes four key components: (i) increasingly stringent emissions standards for new vehicles, (ii) specifications for clean fuels, (iii) programs to assure proper maintenance of in-use vehicles, and (iv) transportation planning and demand management. These emission reduction goals should be achieved in the most cost-effective manner available. Figure 2 illustrates these four key components of a comprehensive vehicle pollution control strategy. Transport planning and demand management Figure 2 Elements of a comprehensive vehicle pollution control strategy

17 Fuel quality standards In setting fuel quality standards, policymakers should be guided by the following general principles: Implementing a successful systems approach to setting fuel standards requires institutional mechanisms that include a variety of stakeholders from government, private sector and civil society, and allows for extensive consultation. In countries where such an institutional mechanism is not yet in place, it should be created. Environmental and public health concerns are the driving force behind improvements in fuel quality, thus the Environment Department should have a major role in setting fuel standards. All countries should develop a shortand medium-term strategy that The main impediment identifies standards to be adopted to adopting state-of-theart new vehicle emissions over the next several years, so as to allow fuel providers and the vehicle industry sufficient time to adapt. technology in Asia is fuel The main impediment to adopting quality, especially lead and state-of-the-art new vehicle emissions sulfur levels in gasoline and technology (equivalent to Euro 3 and 4) in Asia is fuel quality, especially sulfur levels in diesel lead and sulfur levels in gasoline and sulfur levels in diesel. These parameters should receive the highest priority in the development of medium- and longterm strategies for fuel standards. Raising the necessary capital funds is the major issue in investing in new refinery units to manufacture low-sulfur diesel fuels. In developing fuel standards, countries should attempt to work closely with neighboring countries and harmonize

18 8 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA standards where possible. This should not, however, be used as an excuse for delaying or watering down requirements, as harmonization does not mean that all countries must follow the same time schedule. In order to implement stricter fuel standards and make associated costs more acceptable to consumers, countries should institute more and better awareness campaigns. Such campaigns must emphasize the public health consequences of not improving fuel quality. Subsidies that favor fuels which produce high emissions, should be eliminated; tax policies which encourage the use of the cleanest fuels, should be adopted. Conventional fuel improvements should clearly distinguish between primary steps and secondary steps. The former includes removing lead from gasoline, dramatically reducing sulfur levels in gasoline and diesel, and the addition of detergent additives. The latter involves reducing the Reid vapor pressure and the benzene content in gasoline. Gasoline The pollutants of greatest concern from gasoline-fuelled vehicles are carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO x ), lead, and certain toxic hydrocarbons such as benzene. Each of these can be influenced by the composition of the gasoline used by the vehicle. The most important characteristics of gasoline with regard to its impact on emissions are lead content, sulfur concentration, volatility and benzene level. With regard to these characteristics, the following policies are recommended: Lead additives Lead does not exist naturally in gasoline but must be added to it. Since the early 1970s, however, there has been a steady movement toward reducing lead in gasoline and increasingly, the complete elimination of lead. Approximately 85% of all gasoline sold

19 CLEANER FUELS Figure Sri Lanka Phaseout of Lead 2002 Pakistan in Different 2001 Viet Nam Markets 2001 Philippines 2001 Indonesia (Jakarta and Cirebon City) 1973 United States a a Gradual phaseout b Nationwide ban 1980 Japan 1985 Malaysia a 1984 Thailand a 2000 India 2000 PRC 2000 Taipei,China 1999 Bangladesh 1999 Hong Kong, China 1999 Nepal 1998 Malaysia b 1998 Singapore 1996 Thailand b 1996 United States b throughout the world is now unleaded. Figure 3 shows the timing of lead phaseout in different markets. All modern gasoline-fuelled vehicles being produced today can operate satisfactorily on unleaded fuel, and approximately 90% of these are equipped with a catalytic converter that requires the exclusive use of lead-free fuel. There is no longer any doubt that lead is toxic and prevents the use of the clean gasoline vehicle technology that can dramatically reduce CO, HC and NO x emissions. The addition of lead to gasoline should be eliminated as rapidly as possible. Sulfur For cars without catalytic converters, the impact of sulfur on emissions is minimal. For catalyst-equipped cars, however, the impact on CO, HC and NO x emissions can be substantial. Based on the Auto/Oil study, 2 it appears that NO x would decline about 3% per 100-ppm sulfur reduction for a typical catalyst-equipped car.

20 10 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA The situation is even more critical for advanced low-pollution catalyst vehicles. Operation on gasoline containing 330-ppm sulfur will increase exhaust volatile organic compound (VOC) and NO x emissions from current and future new US vehicles (on average) by 40% and 150% respectively, relative to their emissions with fuel containing roughly 30-ppm sulfur. In light of these impacts, it is not surprising that Japan has had typical gasoline sulfur levels under 30 ppm for many years. The US has also adopted a 30-ppm sulfur limit and the European Union (EU) requires gasoline with a maximum sulfur content of no more than 50 ppm in 2005 when Euro 4 standards go into effect. Even more recently, the EU has proposed to limit sulfur levels to a maximum of 10 ppm. In order to maximize the performance of current catalyst technology, gasoline sulfur concentrations should be reduced to a maximum of 500 ppm as soon as new vehicle standards requiring catalysts are introduced. Emerging advanced catalyst technologies capable of achieving very low emissions will require a maximum of 50 ppm or less. A plan for introducing such fuel quality should be adopted early in the development of a longterm vehicle pollution control strategy. Vapor Pressure Another important fuel parameter is vapor pressure. The vapor pressure for each season must be as low as possible in order to minimize evaporation from storage terminals and vehicles, but still sufficiently high to give safe cold starts. An important advantage of gasoline volatility controls is that they can affect emissions from the gasoline distribution system and vehicles already in-use. Gasoline vapor pressure should be reduced to a maximum of 60 kilopascals whenever temperatures in excess of 20 C occur. In tropical or semi-tropical countries such as many in Asia this is all the time.

21 CLEANER FUELS 11 Benzene Benzene is an aromatic hydrocarbon that is present as a gas in both exhaust and evaporative motor vehicle emissions. Benzene in the exhaust, expressed as a percentage of total organic gases, varies depending on the control technology (e.g., catalyst type) and the levels of benzene and other aromatics in the fuel, but is generally about 3 5%. The benzene fraction of evaporative emissions depends on the control technology and fuel composition and characteristics (e.g., benzene level and the evaporation rate), and is generally about 1%. 3 As a general rule, gasoline benzene levels should be capped at 1% as has been done in the EU. Benzene content should be reduced to a maximum of 1% by volume. Oxygenates Blending small percentages of oxygenated compounds such as ethanol, methanol, tertiary butyl alcohol, and methyl tertiarybutyl ether (MTBE) with gasoline has the effect of reducing the volumetric energy content of the fuel while improving its antiknock performance. This makes possible a potential reduction in lead and/or harmful aromatic compounds. Assuming no change in the settings of the fuel metering system, lowering the volumetric energy content will result in a leaner air-fuel mixture, thus helping to reduce exhaust CO and HC emissions. Impact of oxygenate used MTBE. MTBE can be added to gasoline up to 2.7% without any increase in NO x. There are two opposing effects that take place with the addition of oxygenates: (i) enleanment, which tends to raise NO x, and (ii) lower flame temperatures, which tends to reduce NO x. With MTBE levels above 2.7%, the lower flame temperature effect seems to prevail. While the use of MTBE has been found to be very attractive from an air pollution standpoint, recent evidence in the US has

22 12 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA shown that MTBE leaks and spills are a serious threat to drinking water. This has led to a movement to ban its future use in gasoline. The EU has not reached a similar conclusion, but rather prefers to improve the quality of underground storage tanks. Countries considering the use of MTBE should carefully weigh the potential air quality benefits with the potential water quality risks. Ethanol. Ethanol can be added to gasoline at levels as high as 2.1% oxygen without significantly increasing NO x levels, but above that point, NO x levels can increase somewhat. For example, the US Environmental Protection Agency test data on over 100 cars indicates that oxygen levels of 2.7% or more could increase NO x emissions by 3 4%. 4 The Auto/Oil study concluded that there was a statistically significant NO x increase of about 5% with the addition of 10% ethanol (3.5% O 2 ). Since ethanol has a higher volatility than gasoline, the base fuel volatility must be adjusted so as to prevent increased evaporative emissions. As a general rule, without adjustment, volatility will increase by about 1 pound per square inch (psi) when ethanol is added to gasoline. Countries considering ethanol use should carefully evaluate tailpipe CO and HC benefits versus the potential NO x and evaporative HC increases. It should also be noted that in most countries where ethanol is used, it is highly subsidized. Other gasoline properties According to the Auto/Oil study, NO x emissions were lowered by reducing olefins, raised when T 90 was reduced, and only marginally increased when aromatics were lowered. 5 In general, reducing aromatics and T 90, the temperature at which 90% of gasoline evaporates, caused statistically-significant reductions in exhaust mass nonmethane hydrocarbons (NMHC) and CO emissions. Reducing the olefins increased exhaust mass NMHC emissions, however the ozone forming potential of the total vehicle emissions was reduced. 6

23 CLEANER FUELS 13 With regard to toxics, the reduction of aromatics from 45% to 20% caused a 42% reduction in benzene but a 23% increase in formaldehyde, a 20% increase in acetaldehyde and about a 10% increase in 1,3-Butadiene. 7 Reducing olefins from 20% to 5% lowered 1,3-Butadiene by 31% but had insignificant impacts on other toxics. Lowering the T 90 from 360 to 280 o F resulted in statisticallysignificant reductions in benzene, 1,3-Butadiene (37%), formaldehyde (27%) and acetaldehyde (23%). To the extent that the long-term vehicle emissions standards strategy is to adopt Euro 4 standards for light duty vehicles, the European gasoline standards (see Table 1) should be adopted in the same time frame. Detergent or engine deposit control additives are critically important with modern engines and should be mandatory as well. Table 1 Gasoline Specifications in Asia and Europe Benzene Oxygen RVP Sulfur % v/v, Aromatics Olefins % m/m, summer Lead ppm max % % max kpa, max Linked to Euro 3 Vehicle Standards Effective 2000 Lead free Linked to Euro 4 Vehicle Standards Effective 2005 Lead free Bangladesh Lead free kg/m 2 Cambodia 0.15 g/l 3.5 Hong Kong, China Lead free India Lead free 1000 a 5 b Indonesia 0.30 g/l (premix) 62 Japan Lead free Malaysia Lead free Philippines Lead free 2 35 PRC Lead free Singapore Lead free Sri Lanka Lead free Taipei,China Lead free psi Thailand Lead free 500 3% % Viet Nam Lead free g/l = gram per liter, kg/m 2 = kilogram per square meter, kpa = kilopascal, ppm = parts per million, %m/m = percent by mass, %v/v = percent by volume, psi = pound per square inch, RVP = Reid vapor pressure a In Delhi, Mumbai, Kolkata and Chennai sulfur levels are 500 ppm b Benzene 3% in metros and 1% in National Capital Region

24 14 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Diesel fuel Reducing PM emissions from diesel vehicle tends to be of highest priority because PM emissions in general are very hazardous and diesel PM especially is likely to cause cancer Diesel vehicles emit significant quantities of both NO x and particulate. Reducing PM emissions from diesel vehicles tends to be of highest priority because PM emissions in general are very hazardous and diesel PM especially is likely to cause cancer. Sulfur is the most important fuel characteristic to address in order to reduce PM and NO x emissions from diesel engines. Sulfur contributes directly to PM emissions, and high levels of it in diesel preclude the use of the most effective PM and NO x control technologies. Impact on emissions from heavy-duty engines A recent review addressed the impact of fuel composition changes on emissions from current heavy-duty, direct-injection diesel engines. This was based only on studies where there were no significant correlations among germane fuel properties. 8 Conclusions from this review are summarized in Table 2. As shown, the compositional properties of at least some importance with respect to emissions are sulfur, aromatics, and oxygenate content; the physical properties identified are density and the T 90 or T 95 (the temperature at which 90% or 95% of diesel evaporates) distillation temperature. The cetane number/index was also identified as a factor with respect to emissions. The arrows in the first column of Table 2 show the directional changes in these fuel properties which will result in a cleaner fuel. The directional impact on NO x, PM, HC, and CO emissions resulting from changes in each property in the direction indicated are also shown, along with an indication of the relative magnitude of the effect. As shown in Table 2, emissions from engines with high base emission rates (generally older designs) tend to be more sensitive to changes in fuel composition than those from engines with lower base emissions rates (which tend to be newer designs). In addition, changes in all of the fuel properties have been found to have, at most, small impacts on emissions from engines with low base emission rates.

25 CLEANER FUELS 15 Fuel Modification NO x Particulates Reduce Sulfur 0 d Increase Cetane 0 Reduce Total Aromatics c 0 Reduce Density 0 a / b Reduce Polyaromatics c 0 a / b Reduce T /T Table 2 Influence of Fuel Properties on Heavy Duty Diesel Emissions / = relatively large effect, / = small effect, / = very small effect, 0 = no effect a Low emission emitting engine b High emission emitting engine c Polyaromatics are expected to produce a bigger reduction than mono-aromatics. Further studies (e.g., EPA Heavy-duty engine working group) are investigating these parameters d Reducing sulfur from 0.30% to 0.05% gives relatively large benefits; reducing sulfur from 0.05% to lower levels has minimal direct benefit, but is necessary to enable advanced technologies for engines without after-treatment systems Impact on emissions from light-duty vehicles The most recent, comprehensive study of fuel composition impacts on light-duty diesel emissions was performed as part of the EU Program on Emissions, Fuels and Engine Technologies. 9 The generalized results of this study are presented in Table 3. As shown, although there are some differences in terms of the magnitude of fuel composition effects on emissions from vehicles with indirect- and direct-injection engines, the directional impact on emissions is usually the same. NO x Emissions PM Emissions Change IDI a DI b IDI DI Cetane (50 to 58) None Density (0.855 to g/cm 3 ) None T 95 (700 to 620 o F) None Polycyclics (8 to 1 vol %) Table 3 Impact of Fuel Composition Changes on Emissions of Current Light-Duty Diesel Vehicles / = relatively large effects (10% or greater change in emissions), / = small effects (5 to 10% change), / = very small effects (~1 to 5% change), g/cm 3 = grams per cubic centimeter, none = no effect, T 95 = temperature at which diesel evaporates a Indirect-injection engines b Direct-injection engines

26 16 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA A comparison of the heavy duty and light duty tables indicates that there are some instances where changing a given diesel fuel property is expected to have the opposite directional impact on emissions, depending on whether the fuel is being used in a heavy-duty or light-duty engine. Most notable is the increase in NO x emissions from light-duty direct-injection engines in response to a decrease in fuel density, and also the NO x emission increases from both light-duty indirect- and direct-injection engines in response to a decrease in the T 95 temperature. 10 Sulfur Sulphate particulate and SO x emissions, both harmful pollutants, are emitted in direct proportion to the amount of sulfur in diesel fuel. Sulphate PM contributes directly to PM 10 and PM 2.5 emissions 11 and their associated adverse health and environmental effects. SO 2, one fraction of SO x, is a criteria pollutant with associated adverse effects. The health and welfare effects of SO 2 emissions from diesel vehicles are probably much greater than those of an equivalent quantity emitted from a utility stack or industrial boiler, since diesel exhaust is emitted close to the ground level in the The health and welfare effects of SO 2 emissions from diesel vehicles are probably much greater than those of an vicinity of roads, buildings, and concentrations of people. Further, some SO x are also transformed in the atmosphere to sulphate PM with the associated adverse effects noted for PM. 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 SO x and water which also sits on the core s surface. Lowering the sulfur in fuel lowers the SO x fraction of PM thus lowering the overall mass of PM emit- equivalent quantity emitted from a utility stack or industrial boiler, since diesel exhaust is emitted close to the ground level in the vicinity of roads, buildings, and concentrations of people

27 CLEANER FUELS 17 ted. Diesel fuel evaluations carried out in Europe show that reduced sulfur in diesel can lower particulate. For example, lowering the diesel sulfur level from 2000 ppm to 500 ppm reduced the overall particulate from light-duty diesels by 2.4% and from heavy-duty diesels by 13%. 12 The relationship between particulates and sulfur levels was found to be linear; for every 100-ppm reduction in sulfur there will be a 0.16% reduction in particulate from light duty vehicles, and a 0.87% reduction from heavy-duty vehicles. The technology-disabling effect of sulfur in diesel fuel is comparable to lead and sulfur in gasoline. Catalytic converters or NO x adsorbers can eliminate much of the NO x emissions from new diesel engines, but sulfur disables them in much the same way that lead poisons the three-way catalyst. Thus, the presence of sulfur in diesel fuel effectively bars the path to low emissions of conventional pollutants. As stated by a German government petition to the European Commission in support of low-sulfur fuel, A sulphur content of 10 ppm compared to 50 ppm increases the performance and durability of oxidizing catalytic converters, DeNOx catalytic converters and particulate filters, and therefore decreases fuel consumption. There are also lower particulate emissions (due to lower sulphate emissions) with oxidizing catalytic converters. For certain continuously regenerating particulate filters, a sulphur content of 10 ppm is required for the simple reason that otherwise the sulphate particles alone (without any soot) would overstep the future [European] particulate value of 0.02 g/kwh. Figure 4 shows the current and proposed sulfur levels in diesel in Asia, Europe and the United States. In addition to its role as a technology enabler, low-sulfur diesel fuel gives benefits in the form of reduced sulfur-induced corrosion and slower acidification of engine lubricating oil. This leads to longer vehicle maintenance intervals and lower maintenance costs. These benefits can offer significant cost savings to the vehicle owner without the need to purchase new technologies. Therefore, with regard to diesel fuel, the following policies are recommended:

28 18 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Bangladesh 5000 Cambodia 2000 Hong Kong, China India Indonesia 5000 Japan a Malaysia b Pakistan Philippines PRC Republic of Korea 500 Singapore Sri Lanka Taipei,China Thailand Viet Nam European Union United States > 500 ppm ppm < 50 ppm Figure 4 Current and Proposed Sulfur Levels in Diesel in Asia, European Union and United States a Under consideration b Marketed Emerging advanced PM and NO x control technologies capable of achieving very low emissions will require a maximum of 50 ppm sulfur or less. A plan for introducing such fuel quality frequently referred to as ULSD should be adopted early in the development of a long-term vehicle pollution control strategy. Certain advanced diesel control technologies such as NO x adsorbers cannot function properly even with 50-ppm fuel and will require a maximum of 10 ppm. While interim improvements in diesel fuel quality will benefit air quality, it is most efficient and cost effective for a refinery to go directly to ULSD rather than via several interim steps.

29 CLEANER FUELS 19 When ULSD is introduced, strong consideration should be given to retrofitting existing vehicles with oxidation catalysts or diesel PM filters which can achieve significant and rapid PM reductions. An effective means of encouraging the rapid introduction of ULSD beyond traditional command-and-control regulations is to adopt a tax policy that results in higher-sulfur fuels costing more at the pump. Hong Kong, China has successfully implemented such a strategy. Other diesel fuel properties Volatility Diesel fuel consists of a mixture of HC with different molecular weights and boiling points. As a result, as some of it boils away on heating, the boiling point of the remainder increases. This fact is used to characterize the range of HC in fuel in the form of a distillation curve specifying the temperature at which 10%, 20%, etc. of the HC have boiled away. A low 10% boiling point is associated with a significant content of relatively volatile HC. Fuels with this characteristic tend to exhibit somewhat higher HC emissions than others. Aromatic hydrocarbon content Aromatic hydrocarbons are HC compounds containing one or more benzene-like ring structures. They are distinguished from paraffins and napthenes, the other major HC constituents of diesel fuel, which lack such structures. Compared to these other components, aromatic hydrocarbons are denser, have poorer self-ignition qualities, and produce more soot in burning. Ordinarily, straight run diesel fuel produced by simple distillation of crude oil is fairly low in aromatic hydrocarbons. Catalytic cracking of residual oil to increase gasoline and diesel production, however, results in increased aromatic content. A typical straight run diesel might contain 20 25% aromatics by volume, while a diesel

30 20 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA blended from catalytically cracked stocks could have 40 50% aromatics. Aromatic hydrocarbons have poor self-ignition qualities, so that diesel fuels containing a high fraction of aromatics tend to have low cetane numbers. Typical cetane values for straight run diesel are in the range of 50 55; those for highly aromatic diesel fuels are typically 40 45, and may be even lower. This produces more difficulty in cold starting, and increased combustion noise, HC, and NO x due to the increased ignition delay. Increased aromatic content is also correlated with higher particulate emissions. Aromatic hydrocarbons have a greater tendency to form soot in burning, and the poorer combustion quality also appears to increase particulate SOF emissions. Increased aromatic content may also be correlated with increased SOF mutagenicity, possibly due to increased polynuclear aromatics (PNA) and nitro-pna emissions. There is also some evidence that more highly aromatic fuels have a greater tendency to form deposits on fuel injectors and other critical components. Such deposits can interfere with proper fuel-air mixing, greatly increasing PM and HC emissions. Polycyclic aromatic hydrocarbons (PAH) are included in the great number of compounds present in the group of unregulated pollutants emitted from vehicles. Exhaust emissions of PAH (here defined as three-ringed and larger) are distributed between particulate and semi-volatile phases. Some of these compounds in the PAH group are mutagenic in the Ames test and in some cases even cause cancer in animals after skin painting experiments. Because of this fact, it is important to limit PAH emissions from vehicles especially in densely populated high traffic urban areas. An important factor affecting vehicle PAH emissions is the selection of fuel and fuel components. A linear relationship exists between fuel PAH input and PAH emissions. PAH emissions in exhaust consist of uncombusted through-fuel input PAH and PAH formed in the combustion process. Selection of diesel fuel quality with low PAH content [less than or equal to 4 mg/l, sum of PAH (i.e. individual PAH, phenanthrene to coronene, amounts added

31 CLEANER FUELS 21 together)], will reduce PAH exhaust emissions by up to approximately 80% compared to diesel fuel with PAH contents larger than 1 g/l (sum of PAH). By reducing fuel PAH content in commercially available diesel fuel, PAH emissions to the environment will be reduced. 13 Other Other fuel properties may also have an effect on emissions. Fuel density, for instance, may affect the mass of fuel injected into the combustion chamber and thus, the air-fuel ratio. This is because fuel injection pumps meter fuel by volume not by mass, and a denser fuel contains a greater mass in the same volume. Fuel viscosity can also affect the fuel injection characteristics and thus, the mixing rate. Corrosiveness, cleanliness, and fuel lubricating properties can all affect the service life of fuel injection equipment, and possibly contribute to excessive in-use emissions if the equipment is worn out prematurely. While less critical, other diesel fuel properties such as cetane number, density, distillation and polyaromatic content can also have positive or negative impacts on emissions and should be carefully evaluated. To the extent that a long-term vehicle emissions standards strategy is to adopt Euro 4 standards for light duty vehicles and Euro 5 standards for heavy duty vehicles, the European diesel standards as summarized in Table 4 should be adopted in the same time frame Linked with Euro 3 Linked with Euro 4 Diesel Fuel Parameter Vehicle Standards Vehicle Standards Cetane number, min Density 15 o C kg/m 3, max Distillation 95%, v/v o C, max Polyaromatics %v/v, max Sulfur ppm, max Table 4 European Union Diesel Fuel Specification Limits kg/m 3 = kilogram per cubic meter, max = maximum, min = minimum, ppm = parts per million, % m/m = percent by mass, % v/v = percent by volume

32 22 POLICY GUIDELINES FOR REDUCING VEHICLE EMISSIONS IN ASIA Fuel additives Several generic types of diesel fuel additives can have a significant effect on emissions. These include cetane enhancers, smoke suppressants, and detergent additives. In addition, some additive research has been directed specifically at emissions reduction in recent years. Cetane enhancers are used to improve the self-ignition qualities of diesel fuel. These compounds (usually organic nitrates) are generally added to reduce the adverse impact of high aromatic fuels on cold starting and combustion noise. These compounds also appear to reduce the adverse impacts of aromatic hydrocarbons on HC and PM emissions, although PM emissions with the cetane improver are generally still somewhat higher than those from a higher quality fuel able to attain the same cetane rating without the additive. Smoke suppressing additives are organic compounds of calcium, barium, or sometimes magnesium. Added to diesel, these compounds inhibit soot formation during the combustion process and thus, greatly reduce visible smoke emissions. However, they tend to significantly increase the number of very small ultrafine particles that are suspected of being even more hazardous to health. Their effects on the particulate SOF are not fully documented, but one study has shown a significant increase in PAH content and SOF mutagenicity with a barium additive. Particulate sulphate emissions are greatly increased with these additives, since all readily form stable solid metal sulphates, which are emitted in the exhaust. The overall effect of reducing soot and increasing metal sulphate emissions may be either an increase or decrease in the total particulate mass, depending on the soot emission level at the beginning and the amount of additive used. While smoke suppressing additives may appear attractive, their use is not recommended because of the potentially more hazardous ultrafine particle emissions and mutagenicity.

33 CLEANER FUELS 23 Detergent additives (often packaged in combination with a cetane enhancer) help to prevent and remove coke deposits on fuel injector tips and other vulnerable locations. By maintaining new engine injection and mixing characteristics, these deposits can help to decrease in-use PM and HC emissions. A study for the California Air Resources Board estimated the increase in PM emissions from in-use trucks due to fuel injector problems as being more than 50% of new vehicle emissions levels. A significant fraction of this excess is unquestionably due to fuel injector deposits. The use of detergent additives to reduce deposits on injector components is highly recommended, especially on more modern engines. Alternative fuels In addition to conventional gasoline and diesel fuels, many countries around the world have identified significant benefits associated with a shift to alternative fuels, especially CNG, LPG, and ethanol. Besides CNG (mainly composed of methane) and LPG (composed of propane or butane), alternative fuels include methanol, ethanol, hydrogen, electricity, vegetable oils (including biodiesel), synthetic liquid fuels derived from coal, and various fuel blends such as gasohol. Natural gas Natural gas (85-99% methane) is clean burning, cheap and abundant in many parts of the world. Because natural gas is mostly methane, natural gas vehicles (NGVs) have much lower non-methane HC emissions than gasoline vehicles, but higher methane emissions. Since the NGV fuel system is sealed, there are no evaporative emissions and refuelling emissions are negligible. Cold-start emissions from NGVs are also low, since cold-start enrichment is not required. In addition, this reduces both VOC and CO emissions. NO x emissions from uncontrolled NGVs may be higher or