Statenfractie provincie Zeeland

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1 Statenfractie provincie Zeeland Vragen ingevolge artikel 44 reglement van orde aan het College van Gedeputeerde Staten door het statenlid PB.Colijn van de fractie van de ChristenUnie. Onderwerp: Aanvullende vragen Biogas bussen openbaar vervoer. Datum: dinsdag 20 september 2011 Toelichting: Vanaf 2009 is door de Provincie Zeeland en vervoerder Connexxion een overeenkomst aangegaan ter hoogte van circa 1.2 miljoen per jaar met een looptijd tot 2014 teneinde openbaar vervoer met bussen op biogas in Midden Zeeland mogelijk te maken. Reeds eerder stelde onze fractie een aantal vragen waarbij de beantwoording daarvan op sommige punten in tegenspraak lijkt met wetenschappelijke rapporten van TNO. Daarnaast zouden we graag nog enige concluderende vragen beantwoord zien. Vragen: 1. In uw beantwoording geeft u aan dat de milieuwinst van biogasautobussen volgens de Euro IV norm zich vertaalt in minder uitstoot van stikstof en een verminderde uitstoot van fijnstof, alsmede een lagere geluidsoverlast geeft t.o.v. conventionele autobussen. Hoe valt dit te verklaren aan de hand van de rapportage van TNO. MON-RPT- 033-DTS en MON-RPT-033-DTS waarin wordt aangegeven dat de CO2 uitstoot van een aardgasbus gemiddeld 70% hoger is dan die van een dieselbus en ook de uitstoot van fijnstof hoger is dan die van een dieselbus. Daarbij zou de geluidsbelasting van dieselbussen gunstiger zijn dan die van aardgasbussen, terwijl u in uw beantwoording het tegendeel aangeeft. Graag vernemen we van u op welke rapportages uw conclusies gebaseerd zijn en hoe de rapporten van TNO moeten worden geïntepreteerd. 2. Met betrekking tot de jaarlijkse kosten voor de Provincie geeft u aan dat dit 1mln. per jaar tot 2014 betreft. In de begroting is hiervoor jaarlijks 1.2 mln opgenomen. Hoe is dit verschil te verklaren? 3. Uit de beantwoording blijkt dat eventuele Zeeuwse biogas vergistinginstallaties niet zullen worden toegepast voor de Zeeuwse biogasautobussen, omdat de brandstof daarvoor elders aan de vulpunten wordt toegevoegd; is deze conclusie juist? 4. Uit de beantwoording blijkt dat indien de SDE subsidieregeling niet aan Zeeuwse initiatieven wordt toegekend en verder wordt geïmplementeerd, er ook voor het gebruik van biogasautobussen nimmer een brake-evenpoint in

2 kosten en opbrengsten zal ontstaan in vergelijk tot alternatieven zoals diesel, zonnecel of hybride autobussen. Is deze conclusie juist? Hoogachtend, Statenfractie ChristenUnie Paul Colijn Tel:

3 TNO report MON-RPT-033-DTS VDL Ambassador diesel EEV bus: emission measurements and comparison with other buses. Stieltjesweg 1 P.O. Box AD Delft The Netherlands T F info-ient@tno.nl Date 12 November 2007 Author(s) Gerrit Kadijk Ruud Verbeek Assignor VDL Bus & Coach N.V. Hoevenweg AW EINDHOVEN Project number Number of pages 26 (incl. appendices) Number of appendices 2 All rights reserved. No part of this report may be reproduced and/or published in any form by print, photoprint, microfilm or any other means without the previous written permission from TNO. All information which is classified according to Dutch regulations shall be treated by the recipient in the same way as classified information of corresponding value in his own country. No part of this information will be disclosed to any third party. In case this report was drafted on instructions, the rights and obligations of contracting parties are subject to either the Standard Conditions for Research Instructions given to TNO, or the relevant agreement concluded between the contracting parties. Submitting the report for inspection to parties who have a direct interest is permitted TNO

4 TNO report MON-RPT-033-DTS / 26

5 TNO report MON-RPT-033-DTS / 26 Summary VDL Bus & Coach asked TNO to compare the emissions and fuel consumption of the lightweight EEV 1 VDL Ambassador SB 200 bus with other state of the art CNG and diesel buses. The emission limits of buses and other heavy-duty vehicles are generally specified by measurements on an engine test bed. However, the emissions (and fuel consumption) in real world applications are not only dependent on the emission level and fuel consumption of the engine during the official test cycles. They are also dependent on the driving resistance of the bus and the emissions of the engine under real world driving conditions. Consequently, for a valid comparison between buses, testing of complete buses is desirable. The VDL Ambassador SB 200 bus has about 20% lower mass than most other buses and the engine is equipped with a wall flow diesel particulate filter. This engine fulfils the EEV limits. This concept is in theory suitable to achieve low real world emissions such as for CO 2, particulates (PM10), NOx, CO and HC and low fuel consumption. Within this project, the VDL Ambassador bus is tested on the transient chassis dynamometer (rolling road) of VTT in Finland. Subsequently the results are compared to those of Euro IV diesel buses and EEV CNG buses which were also measured at those facilities. Two types of applications are evaluated: typical city bus application represented by the Braunschweig cycle and typical regional bus application represented by the Helsinki 3 cycle. The measurements and comparison lead to the following conclusions for the Ambassador SB200 bus: The CO 2 emission is respectively 865 and 741 g/km for typical city bus application and typical regional bus application. This is lower than the EEV CNG buses measured ( g/km for city application). It is also lower than other (heavier) diesel buses ( g/km for city application). The particulates emission is respectively g/km and g/km for typical city bus application and typical regional bus application. This is lower than EEV CNG buses tested ( g/km for city application). It is much lower than the other diesel buses measured (buses without wall-flow diesel particulate filter). The number of fine and ultra fine particles and the particle size distribution of the Ambassador bus are comparable with those of the CNG buses. The number is two orders of magnitude lower than standard Euro III and Euro IV diesel buses measured at VTT. The NOx emission is respectively 4.6 g/km and 2.8 g/km for typical city bus application and typical regional bus application. For city application the figure of the Ambassador bus (4.6 g/km) is at the top of the range of the EEV CNG buses tested ( g/km). For regional bus application 1 EEV stands for Enhanced Environmentally Friendly Vehicle

6 TNO report MON-RPT-033-DTS / 26 no values were available for CNG buses. The NO 2 emission of the Ambassador bus is relatively high (35% tot 42% of the NOx emission). The CO emission is very low: 0.1 g/km. This is the same value as the best diesel and CNG buses. Some other buses in the comparison have a much higher CO emission. The emission of unburnt HC is negligible, in line with other Euro IV or better diesel buses. CNG buses often have a higher HC emission (up to about 2 g/km, primarily methane). In general it can be concluded that large variations are seen in real world CO 2, particulate and NOx emissions for both diesel and CNG buses complying with the latest legislation. As a result the real world emissions of each bus needs to be evaluated in order to determine which bus (diesel or CNG) would lead to the lowest emission for a particular application.

7 TNO report MON-RPT-033-DTS / 26 Contents Summary Introduction Aim and approach Components of exhaust emission Experimental procedure Vehicle specifications Engine specifications Test Program Results VDL bus test results Comparison of VDL buses with previously measured buses Discussion Conclusions References Signature Appendix A: Test Cycles Appendix B: Photographs

8 TNO report MON-RPT-033-DTS / 26 1 Introduction 1.1 Aim and approach VDL Bus & Coach ordered TNO Science and Industry to carry out a bus exhaust emission benchmark program. VDL is a manufacturer of coaches and city buses, that are equipped with diesel engines with EEV technology. The main objective of this work is to compare the VDL bus fuel consumption and exhaust emissions (CO 2, particulates, NOx, CO, HC) with other buses which are equipped with diesel/cng Euro IV/V or EEV technology. The VDL Ambassador SB200 bus is developed for operating in urban and regional areas. A Cummins 6.7 litre engine with SCR catalyst and CRT (oxidation catalyst with diesel particulate or soot filter) is installed and complies with EEV exhaust emission limits. The bus is constructed with light weight materials and has a mass of only 8800 kg. Due to the numerous heavy duty vehicle applications, the emission type approval is for the engine (plus aftertreatment system) and not for the complete vehicle. The European Steady state Cycle (ESC) and the European Transient Cycle (ETC) are used as engine emission type approval tests and the relative speed-load patterns are related to the engine characteristics. In general tail pipe emissions are optimized for the ESC and ETC tests. Daily vehicle use is very complex and speed-load patterns mostly differ from ESC/ETC speed-load patterns. For that reason the emissions in the real world application can deviate from those expected based on the type approval results. This program is carried out to measure the exhaust emission and fuel consumption performance of the VDL Ambassador SB 200 bus under specific bus operation conditions. Internationally accepted test cycles for bus operation are used. In that way the results can be compared with those of other buses with diesel and CNG engines. The test cycles used are: Braunschweig cycle: typical city application: average speed: 22.5 km/h, maximum speed 58.2 km/h Helsinki 3 cycle: typical regional bus application: average speed: 41.2 km/h, maximum speed 71.7 km/h SORT3 cycle: cycle for regional bus application developed by the UITP (international association for public transport). The emission measurements and comparison of this project included the following components: Regulated components: nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC) and particulate matter (also referred to as soot, fine dust or PM10). Non-regulated components: nitrogen dioxide (NO 2 ) and carbon dioxide CO 2, Particle size distribution: measurement of the number and size of particulates between about 20 and 300 nanometer.

9 TNO report MON-RPT-033-DTS / 26 The results are compared with data of diesel and CNG buses with EEV or Euro IV technology which are published by VTT-Processes Finland: VTT investigated the fuel consumption and exhaust emission performance of a number of diesel and CNG buses in and [1, 2]. In order to have directly comparable data the current test program is also carried out on the VTT transient chassis dynamometer. 1.2 Components of exhaust emission In this section, a brief overview of sources and effects of the various exhaust emission components is given. Components of exhaust emissions are: Regulated components: nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC) and particulate matter (PM) Non-regulated components: nitrogen dioxide (NO 2 ), polycyclic aromatic hydrocarbons (PAH), carbon dioxide (CO 2 ), nitrous oxide (N 2 O) and methane (CH 4 ) Metal oxides originating from lubricant and engine wear. PM in relation to particle size distribution. Carbon dioxide (CO 2 ) Carbon dioxide is formed by complete burning of carbon in fuels. This gas contributes to the greenhouse effect which contributes to global warming. Particulate matter (PM) Particulate matter represents a complex mixture of organic and inorganic materials. The size of diesel engine particles ranges from 20 to 400 nanometer; the highest numbers are found in the range from 20 to 100 nm. Within air quality assessments, the following particle sizes are distinguished: Coarse: > 2.5 microns. Fine: 0.1 to 2.5 microns. Ultra-fine (nano): < 0.1 micron. Nitrogen oxide Nitrogen oxide (NOx) in exhaust gases of combustion engines is a mixture of NO and NO 2. NO 2 (nitrogen dioxide) belongs to a family of highly reactive gases, the nitrogen oxides (NOx). NO 2 is one of the most important air pollutants in urban areas. NO 2 is more toxic than NO, and it has a large ozone formation potential. This is the reason why NO 2 plays an important role in air quality standards. Nitrous oxide (N 2 O) Dinitrogen oxide contributes to ozone depletion and can be produced by oxidation catalysts. Carbon monoxide (CO) Carbon monoxide is a colourless, odourless and poisonous gas produced by incomplete burning of carbon in fuels. The binding of carbon monoxide with haemoglobin to form COHb reduces the oxygen-carrying capacity of the blood and impairs the release of oxygen from haemoglobin, reducing the delivery of oxygen to the organs and tissues.

10 TNO report MON-RPT-033-DTS / 26 Polycyclic Aromatic Hydrocarbons (PAH) PAH consists of a wide range of compounds that are emitted from a number of sources. Airborne PAH include substances which, when inhaled, may induce lung cancer in humans. PAH are a large group of compounds and their origin is fuel and lubricant; they consist of two or more fused aromatic rings consisting of carbon and hydrogen. The physical and chemical properties of the individual PAH vary to a large extend. PAHs can be found in volatile, semi-volatile and solid form. In exhaust gas, solid phase PAHs are particle-bound. In this benchmark test no determination of PAHs are carried out. Methane (CH 4 ) Methane can be emitted in CNG fuelled vehicles and contributes severely to global warming. In this project the emission measurements and comparison are limited to the regulated emissions, NO 2, CO 2 and particle size distribution.

11 TNO report MON-RPT-033-DTS / 26 2 Experimental procedure 2.1 Vehicle specifications The specific data of the CNG and diesel buses are presented in Table 1. The VDL bus road load curve is derived from a similar bus (equal mass, similar tyres) and is corrected for the frontal area. The tyre rolling resistances are assumed to be equal. This frontal area correction has a minor influence on the total absorbed load. Table 1: Bus parameters CNG bus Diesel bus VDL diesel bus Emission class EEV Euro IV EEV Trade mark tyre Michelin Michelin Goodyear Tyre type XZA XZA Metro MCS Front tyre size 275/70R /70R /70R19.5 Number front tyres Rear tyre size 275/70R /70R /70R19.5 Number rear tyres Vehicle height [m] Vehicle width [m] Chassis front area [m^2] Vehicle mass unladen [kg] Vehicle length [m] Chassis dyno settings vehicle Abs.vehicle 10 km/h [kw] Abs.vehicle 20 km/h [kw] Abs.vehicle 30 km/h [kw] Abs.vehicle 40 km/h [kw] Abs.vehicle 50 km/h [kw] Abs.vehicle 60 km/h [kw] Abs.vehicle 70 km/h [kw] The dynamometer set-up values of the VDL bus are Load Inertia [kg] F0 F1 F2 Unloaded Half load Full load SORT3 load

12 TNO report MON-RPT-033-DTS / Engine specifications The VDL Ambassador bus is equipped with a Cummins diesel engine with SCR catalyst with AdBlue injection and CRT (oxidation catalyst with wall flow diesel particulate filter). The engine complies with the EEV exhaust emission limits. In Table 2 the engine type approval test results are listed. The emissions are well below the EEV limit values. The CO, THC and PM are only 0-8% of the EEV limit. NOx emission is about 25% below the EEV limit. Table 2: Cummins ISBe5 225B EEV diesel engine Trade Mark Cummins Type ISBe5 225B Swept volume [dm 3 ] 6.7 Max. Power [kw] 2500 rpm Max. Torque [Nm] 1500 rpm ESC test results EEV limit Result Percentage of limit [g/kwh] [g/kwh] [%] CO HC NOx PM ETC test EEV limit Result Rel. result results [g/kwh] [g/kwh] [%] CO HC NOx PM

13 TNO report MON-RPT-033-DTS / Test Program The test program of the VDL Ambassador bus was carried out at VTT Processes Finland in September, 2007, and was supervised by TNO. Prior to the measurements VDL and TNO discussed the test program at VTT. Special attention was given to the measurement program, the road load settings and the measurement procedures. In Table 3 and 4 an overview of the executed tests is presented. The Braunschweig cycle is a city bus cycle. The Helsinki 3 and SORT 3 cycles cover regional bus use. Table 3: Executed tests VDL Ambassador bus Test cycle Load Inertia Av. speed Distance (km) Work [kg] [km/h] [km] [kwh] Braunschweig fully laden Braunschweig fully laden Braunschweig half load Braunschweig half load Braunschweig empty vehicle Braunschweig empty vehicle SORT 3 Sort load SORT 3 Sort load Helsinki 3 Sort load Helsinki 3 Sort load Table 4: Measured parameters Fuel consumption CO, THC, NO/NOx CO 2 PM Particle Size Distribution (ELPI) Braunschweig X X X SORT 3 X X X Helsinki 3 X X X

14 TNO report MON-RPT-033-DTS / 26 3 Results 3.1 VDL bus test results The emission results of the VDL Ambassador bus for different test cycles and different (passengers) loads of the bus are presented in Table 5. Every test was carried out three times and average values are presented. Table 5: VDL bus measured test results Cycle Braunschweig Braunschweig* Number of tests Vehicle mass [kg] Load [kg] Total mass [kg] Work [kwh] Distance [m] CO [g/km] HC [g/km] NO x [g/km] NO 2 [g/km] PM [g/km] Fuel [l/100 km] CO 2 [g/km] Tscr [ C] * Interpolated results Braunschweig Braunschweig Helsinki 3 SORT 3 Particulates, CO and HC emissions are extremely low due to the wall flow diesel particulate filter and integrated oxidation catalyst. Due to the relatively low mass of the VDL Ambassador bus, CO 2 emission and fuel consumption are also low. From Table 5 it can be concluded that the emission of NOx, NO 2, CO and HC are not dependent on the vehicle mass. The NOx and NO 2 emissions even go down somewhat with increasing vehicle mass (Braunschweig cycle) and the NOx and NO 2 emissions are considerably lower during the Helsinki 3 cycle. This is due to the minimum required SCR catalyst temperature for NOx conversion. Higher vehicle mass or the Helsinki 3 cycle result in a higher average engine load which in turn results in a higher average catalyst temperature. The minimum temperature requirement is met during a higher percentage of time, which results in lower emissions. After the Braunschweig tests two Helsinki 3 cycles were carried out. Due to the low exhaust gas temperatures ( C) soot may be stored in the diesel particulate filter. Additionally Helsinki 3 cycles were carried out in duplicate ( C). Special attention was given to possible particulates emission due to diesel particulate

15 TNO report MON-RPT-033-DTS / 26 filter regeneration. No increase of particulate emissions in the Helsinki 3 cycles was measured which could be caused by a regeneration phenomena. The SORT test cycles are developed by UITP (international association for public transport) to create a clear communication between bus suppliers and end users. It is mainly developed as a fuel consumption test. The test specifications are vehicle based. A certain time speed profile must be followed. The SORT 3 test is developed for regional buses and the test results are reported in Table Comparison of VDL buses with previously measured buses Braunschweig test cycle In Table 6 the exhaust emission and fuel consumption performance of the VDL Ambassador bus (marked as brand A) and other diesel and CNG buses are compared. The brands B, D, E, F, G, and H are measured in earlier VTT bus programs (published in 2004 and 2007). The Euro IV diesel buses (brand F,G,H) are tested with 1500 kg load instead of 2800 kg. Load corrections are made for fuel consumption and CO 2 emissions. Table 6: Benchmark test results Braunschweig cycle (A is VDL Ambassador Bus) Engine type Diesel CNG CNG CNG Diesel Diesel Diesel SCR LB LM SM SCR SCR EGR CRT OC TWC TWC Class EEV EEV EEV EEV Euro IV Euro IV Euro IV Brand A B D E F G H Vehicle mass [kg] Load [kg] Total mass [kg] Power [kw] Work [kwh] CO [g/km] HC [g/km] NO x [g/km] NO 2 [g/km] PM [g/km] Fuel cons. [l/100 km] CO 2 [g/km] Fuel cons. corr. for 2800 kg load [l/100 km] CO 2 corr. for 2800 kg load [g/km] The following points should be noted:

16 TNO report MON-RPT-033-DTS / 26 Comparison of VDL bus with EEV CNG buses The VDL bus has a 17-40% lower CO 2 emission during the Braunschweig cycle than the tested CNG buses. The reasons for this low CO 2 emission are: - low VDL vehicle mass - high mass CNG buses - high engine efficiency of the diesel engine The particulates emission of the Ambassador bus is g/km. This is lower than EEV CNG buses tested ( g/km). The NOx emission is 4.6 g/km. This is at the top of the range of the CNG EEV buses ( g/km). The HC and CO emission level is lower than those of the CNG buses. CO emission of the CNG buses ranges from 0.2 to 2.6 g/km, while the HC emission ranges from 0.2 to 1.9 g/km. CO and HC emission for the Ambassador bus are respectively 0.1 and 0.0 g/km. Comparison of VDL Ambassador bus with Euro IV diesel buses Due to the relatively low vehicle mass the VDL Ambassador SB200 bus has lower fuel consumption in the Braunschweig cycle than other diesel buses. A 20-24% mass reduction results in a fuel consumption reduction of 20-22% (44/45 versus 35 liter per test) in the Braunschweig cycle. This also results in a reduction of CO 2 emissions. Particulate emission of the Ambassador bus is at least a factor 8 lower than the diesel Euro IV buses. The NOx emission of the Ambassador bus is comparable to the best Euro IV diesel bus and about 50% lower than the 2 other diesel Euro 4 buses. HC is very low for all diesel buses. Two diesel Euro IV buses show a high or very high CO emission: respectively 1.3 and 8.6 g/km Helsinki 3 test cycle In Table 7 the Helsinki 3 test results are reported. Load corrections are made for fuel consumption and CO 2 emissions. Due to the relatively low vehicle mass the VDL Ambassador bus has a lower fuel consumption in the Helsinki cycle than other diesel buses. The 20-24% lower mass results in a fuel consumption reduction of 15-23% (34,35,37 versus 29 liter per test). This also results in a reduction of CO 2 emissions. The Helsinki 3 NOx emissions are 2.8 g/km instead of 4.6 g/km in the Braunschweig cycle. This indicates that Helsinki 3 cycle corresponds better to the ESC/ETC cycle than the Braunschweig cycle.

17 TNO report MON-RPT-033-DTS / 26 Table 7: Benchmark test results Helsinki 3 test cycle (A is VDL Ambassador bus) Engine type Diesel Diesel Diesel Diesel SCR SCR SCR EGR CRT Class EEV Euro IV Euro IV Euro IV Brand A F G H Vehicle mass [kg] Load [kg] Total mass [kg] Power [kw] Work [kwh] CO [g/km] HC [g/km] NO x [g/km] NO 2 [g/km] PM [g/km] Fuel cons. [l/100 km] CO 2 [g/km] Fuel cons. corr. for 2980 kg load [l/100 km] CO 2 corr. for 2980 kg load [g/km]

18 TNO report MON-RPT-033-DTS / Particle size distribution Particle size distribution was measured with ELPI (Electrical low pressure impactor). The ELPI measures particle size distribution and concentration in real-time. It operates in the size range from 15 nm 6 µm. See figure 1. Particulates in all the cycles were close to the background level of the dilution tunnel. Only in the Helsinki 3 cycle the smallest nanoparticle mode (between nm) was slightly increased. Anyway the particle number emissions of the VDL bus were of the same order of magnitude as those of CNG EEV vehicle. Only the smallest nanoparticles were systematically somewhat higher. Emissions did not follow the vehicle loading but had rather slowly increasing or decreasing flow shape. Throughout the particle size range of Da 16 nm 6 µm, the number emission levels of the VDL bus were times lower than from Euro III and Euro IV diesel vehicles. Figure 1: Particle size distribution and concentration measurements Particle number dn/dlogda (#/km) 1.0E E E E E E E E+08 ELPI comparison: VDL vs. others + tunnel background DI Euro 3 ox cat Br 100 % DI Euro 4 SCR Br 100 % VDL Br 100 % VDL Br 0 % VDL Sort 3 VDL Hki 3 CNG EEV Br 100 % CNG tunnel background 1.0E E ELPI Aerodynamic diameter Da (nm)

19 TNO report MON-RPT-033-DTS / 26 4 Discussion Need for measuring real world emissions The emissions of heavy-duty engines such as used for buses are generally expressed in g/kwh, which means gram per unit of mechanical energy delivered at the output shaft of the engine. The emissions of a vehicle or a bus in gram per kilometre are dependent on the formal engine emission level in g/kwh but also on other factors. These are: - The amount of mechanical energy needed to drive the bus. This is dependent on the driving resistance of the bus and on possible engine driven auxiliaries such as the air conditioning. The driving resistance is the sum of rolling resistance and air resistance. - To what extent the engine emissions change under representative driving conditions compared to the conditions of the official test cycle. Due to this, it is only possible to really compare the emission of buses by actually measuring them under their real world driving conditions. For buses this is even more the case because their engine conditions deviate considerably from those during the official test cycle. Evaluation of the VDL bus with earlier results at VTT VDL Bus & Coach has striven to design a bus with good emissions in practice: a) by choosing a specific EEV diesel engine and b) by making a lightweight bus with consequently a low driving resistance. The EEV diesel engine is relatively clean, because it has a wall flow diesel particulate filter and also the NOx emission is about 25% below the EEV limit value. The particulate emission is far below the limit due to the wall flow particulate filter. The measurements carried out show that the tested Ambassador concept works relatively well, especially for particulate emissions, fuel consumption and CO 2 : Particulates emission for the Ambassador bus is similar as the best CNG buses and a lot lower than the other Euro IV diesel buses measured. This is especially due to the wall flow particulates filter. Fuel consumption and CO 2 emission are some 15% to 40% lower than those of the other diesel and CNG buses measured at VTT in Finland. This is especially due to the low mass of the bus in combination with the efficiency of the diesel engine. For NOx emissions, the situation is more complex. In the tables 6 and 7 it can be seen that the NOx emissions vary considerably dependent on the particular bus. During the Braunschweig cycle the range is 4.4 to 9.6 g/km for the diesel buses and 2.1 to 4.5 g/km for the natural gas buses measured at the facilities of VTT in Finland. For the Helsinki 3 cycle (regional bus transport), the range is even wider namely 0.7 to 6.1 g/km for the diesel buses. NOx emission is very sensitive to the driving conditions or load pattern of the engine in its application.

20 TNO report MON-RPT-033-DTS / 26 The NOx emission of the VDL Ambassador bus was respectively 4.6 and 2.8 g/km for the Braunschweig and Helsinki 3 cycle. Consequently, for city bus application the VDL bus ranks amongst the best diesel buses and for regional bus application well below the average of the diesel buses evaluated. The best CNG buses have a 50% lower NOx emission for city bus application, but they sometimes show a higher CO and HC emission (also some diesel Euro IV buses show a higher CO emission). The HC emission of CNG buses is primarily methane (CH 4 ). Methane is not very toxic, but it is a greenhouse gas. The CNG buses showed a negligible NO 2 emission, while for the Ambassador bus the NO 2 share of the NOx was 35-42%. No data on NO 2 is available for the other diesel buses. Comparison to other work in the literature A comprehensive real world emission test program was recently also carried out by FVT (Forschungsgesellschaft für Verbrennungskraftmaschinen und Thermodynamik mbh in Graz Austria) [4]. In this study 4 diesel and 4 CNG buses were measured on their transient chassis dynamometer. These buses included 1 EEV diesel bus, 2 EEV CNG buses and 1 Euro IV CNG bus. Some key results of this study are described below. CO 2 emission during the Braunschweig cycle: - Diesel EEV : 1077 g/km (1 bus) - CNG EEV / Euro IV : g/km (3 buses) Particulate emission during the Braunschweig cycle: - Diesel EEV : g/km (1 bus) - CNG EEV: and g/km (2 buses) - CNG Euro IV: g/km (1 bus) NOx emission during the Braunschweig cycle: - Diesel EEV : 4.3 g/km (1 bus) - CNG EEV: 1.7 and 4 g/km ( 2 buses) - CNG Euro IV: 6.3 g/km (1 bus) From the results, the following can be concluded: The CO 2 emission of the diesel EEV bus is comparable to that of the best CNG bus. The difference in CO 2 emissions between CNG buses is quite large. The particulates emission of both the diesel EEV and CNG buses is very low, however the particulate emission of the diesel bus is the lowest. It should be noted that this diesel EEV bus is equipped with a wall flow diesel particulate filter. There is a considerable difference in NOx emission between the 2 CNG EEV buses. The diesel EEV bus NOx is comparable to the higher emitting CNG EEV bus. When the results are compared to the VTT results (Table 6), it can be concluded that the emissions are very similar for both the CNG buses and the diesel EEV. The only exception is the CO 2 emission of the VDL Ambassador bus which is substantially lower.

21 TNO report MON-RPT-033-DTS / 26 Implications Based on this comparison, it can be concluded that the best diesel buses fall only somewhat behind the best CNG buses with respect to NOx and NO 2 emissions. For all other components the emissions of the diesel bus can be equivalent or better than those of the CNG bus. For both technologies further improvements are probably possible. For the diesel engine it is especially important that SCR denox catalyst remains within its temperature operating range during a larger percentage of the time. In general it can be concluded that large variations are seen in real world CO 2, particulate and NOx emissions for both diesel and CNG buses complying with the latest legislation. As a result the real world emissions of each bus needs to be evaluated in order to determine which bus (diesel or CNG) would lead to the lowest emission for a particular application.

22 TNO report MON-RPT-033-DTS / 26 5 Conclusions The lightweight VDL EEV Ambassador SB 200 bus has been tested on a transient chassis dynamometer and the results are compared to those of heavier state-of-the-art diesel buses (measured in 2006) and three CNG buses measured in the 2004 VTT program. This leads to the following conclusions: The CO 2 emission is respectively 864 and 741 g/km for typical city bus application and typical regional bus application. This is lower than the EEV CNG buses measured ( g/km for city application). It is also lower than other (heavier) diesel buses ( g/km for city application). The particulates emission is respectively g/km and g/km for typical city bus application and typical regional bus application. This is lower than EEV CNG buses tested ( g/km for city application). It is much lower than the other diesel buses measured (buses without wall-flow diesel particulate filter). The number of fine and ultra fine particles and the particle size distribution of the Ambassador bus are comparable with those of the CNG buses. The number is two orders of magnitude lower than standard Euro III and Euro IV diesel buses measured at VTT. The NOx emission is respectively 4.6 g/km and 2.8 g/km for typical city bus application and typical regional bus application. For city application the figure of the Ambassador bus (4.6 g/km) is at the top of the range of the EEV CNG buses tested ( g/km). For regional bus application no values were available for CNG buses. The NO 2 emission of the Ambassador bus is relatively high (35% tot 42% of the NOx emission). The CO emission is very low: 0.1 g/km. This is the same value as the best diesel and CNG buses. Some other buses in the comparison have a much higher CO emission. The emission of unburnt HC is negligible, in line with other Euro IV or better diesel buses. CNG buses often have a higher HC emission (up to about 2 g/km, primarily methane). In general it can be concluded that large variations are seen in real world CO 2, particulate and NOx emissions for both diesel and CNG buses complying with the latest legislation. As a result the real world emissions of each bus needs to be evaluated in order to determine which bus (diesel or CNG) would lead to the lowest emission for a particular application.

23 TNO report MON-RPT-033-DTS / 26 6 References [1] Nils-Olof Nylund, Kimmo Erkkilä, Maija Lappi & Markku Ikonen, VTT Processes, Transient bus emission study: Comparison of emissions from diesel and natural gas buses, VTT research report, PRO3/P5150/04, dated [2] Nils-Olof Nylund, Kimmo Erkkilä & Tuukka Hartikka, VTT Processes, Fuel consumption and exhaust emissions of urban buses, 2007 [3] Kimmo Erkkilä, VTT Processes, Emission and fuel consumption measurements for lightweight bus, VTT-S [4] Stefan Hausberger, Thomas Vuckovic, FVT, Emissions and fuel consumption of clean city bus concepts. Report nb. FVT-85/06 Haus Em 29/ , dated

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25 TNO report MON-RPT-033-DTS / 26

26 TNO report MON-RPT-033-DTS / 26 Appendix A: Test cycles 70 Braunschweig cycle Speed [km/h] Time [s] 80 Helsinki 3 cycle Speed [km/h] Time [s]

27 TNO report MON-RPT-033-DTS / SORT3 cycle x Speed [km/h] Time [s]

28 TNO report MON-RPT-033-DTS / 26 Appendix B: photographs

29 Stieltjesweg 1 Postbus AD Delft TNO-rapport MON-RPT-033-DTS VDL Ambassador diesel EEV bus: Emissiemetingen en vergelijking met andere bussen T F info-ient@tno.nl Datum 21 november 2007 Auteur(s) Gerrit Kadijk Ruud Verbeek Opdrachtgever VDL Bus & Coach N.V. Hoevenweg AW Eindhoven Projectnummer Aantal pagina's 25 (incl. bijlagen) Aantal bijlagen 2 Alle rechten voorbehouden. Niets uit dit rapport mag worden vermenigvuldigd en/of openbaar gemaakt door middel van druk, fotokopie, microfilm of op welke andere wijze dan ook, zonder voorafgaande schriftelijke toestemming van TNO. Indien dit rapport in opdracht werd uitgebracht, wordt voor de rechten en verplichtingen van opdrachtgever en opdrachtnemer verwezen naar de Algemene Voorwaarden voor onderzoeksopdrachten aan TNO, dan wel de betreffende terzake tussen de partijen gesloten overeenkomst. Het ter inzage geven van het TNO-rapport aan direct belanghebbenden is toegestaan TNO

30 TNO-rapport MON-RPT-033-DTS / 25 Samenvatting VDL Bus & Coach heeft TNO verzocht de uitlaatgasemissies en het brandstofverbruik van de lichtgewicht EEV VDL Ambassador SB200 bus te meten en te vergelijken met die van moderne aardgas- en dieselbussen De emissielimieten van bussen en vrachtwagens worden normaal gespecificeerd aan de hand van motorproefstandsmetingen. Echter in de praktijk zijn de emissies en het brandstofverbruik niet alleen afhankelijk van het emissieniveau en het brandstofverbruik van de motor tijdens de officiële testcycli. De emissies zijn ook afhankelijk van de rijweerstanden van de bus en de emissies van de bus in praktijkomstandigheden. Voor een goede vergelijking van bussen is het daarom wenselijk om complete voertuigen te testen. De VDL Ambassador SB200 bus weegt ongeveer 20% minder dan de meeste overige bussen. De motor is uitgerust met een gesloten roetfilter (type: wall-flow) en voldoet aan EEV emissie-eisen. Dit concept is in principe in staat om lage praktijkemissies te realiseren, zoals voor CO 2, deeltjes (PM10), NO x, CO en HC en een laag brandstofverbruik. Binnen dit project is de VDL Ambassador bus beproefd op de dynamische rollenbank van VTT in Finland. Vervolgens zijn deze resultaten vergeleken met die van Euro IV dieselbussen en EEV aardgasbussen die ook door VTT zijn gemeten. Twee typen toepassingen zijn geëvalueerd: typisch stadsbusgebruik middels de Braunschweigcyclus en typisch regionaal busgebruik middels de Helsinki 3 cyclus. De metingen en de vergelijking leiden tot de volgende conclusies voor de VDL Ambassador SB200 bus: De CO 2 emissie is respectievelijk 865 en 741 g/km voor typisch stadsbusgebruik en typisch regionaal busgebruik. Dit is lager dan de geteste EEV aardgasbussen ( g/km voor stadsbusgebruik). Het is ook lager dan andere (zwaardere) dieselbussen ( g/km voor stadsbusgebruik). De deeltjesemissie is respectievelijk g/km en g/km voor typisch stadsbusgebruik en typisch regionaal busgebruik. Dit is minder dan de geteste EEV aardgasbussen ( g/km voor stadsbusgebruik). Het is aanzienlijk lager dan de overige gemeten dieselbussen (bussen zonder gesloten roetfilter). De aantallen ultrafijne deeltjes en de deeltjesgrootteverdeling van de VDL Ambassador SB200 bus zijn vergelijkbaar met die van aardgasbussen. Het deeltjesaantal is enkele ordes lager dan dat van door VTT gemeten standaard Euro III en Euro IV dieselbussen. De NO x emissie is respectievelijk 4.6 g/km en 2.8 g/km voor typisch stadsbusgebruik en typisch regionaal busgebruik. Voor stadsbusgebruik ligt het resultaat van de Ambassador bus (4.6 g/km) aan de bovenkant van de band van de resultaten van aardgasbussen (

31 TNO-rapport MON-RPT-033-DTS / 25 g/km). Voor typisch regionaal busgebruik zijn voor aardgasbussen geen meetwaarden beschikbaar. De NO 2 emissie van de Ambassador bus is relatief hoog (35% tot 42 % van de totale NOx emissie). De CO emissie is zeer laag: 0.1 g/km. Dit is eenzelfde waarde als de beste diesel- of aardgasbussen. Sommige bussen in deze vergelijking hebben een veel hogere CO emissie. De emissie van onverbrande koolwaterstoffen (HC) is verwaarloosbaar, dit is in lijn met Euro IV en betere dieselbussen. Aardgasbussen hebben vaak een hogere HC emissie (tot ca 2 g/km, dit is hoofdzakelijk methaan) In het algemeen kan worden geconcludeerd dat er zowel voor diesel- als aardgasbussen, die voldoen aan de huidige emissienormen, grote variaties optreden in praktijkemissies van CO 2, deeltjes en NO x. Dientengevolge dienen de praktijkemissies van iedere bus te worden geëvalueerd om te kunnen bepalen welke bus (diesel of aardgas) zal resulteren in de laagste emissies in een bepaalde toepassing.

32 TNO-rapport MON-RPT-033-DTS / 25 Inhoudsopgave 1 Inleiding Doelstelling en aanpak Uitlaatgasemissie komponenten Onderzoeksopzet Voertuigspecificatie Motorspecificaties Meetprogramma Resultaten Meetresultaten VDL bus Vergelijk VDL-bus met overige aardgas- en dieselbussen Discussie Conclusies Referenties Ondertekening... 22

33 TNO-rapport MON-RPT-033-DTS / 25 1 Inleiding 1.1 Doelstelling en aanpak VDL Bus & Coach heeft TNO Industrie en Techniek opdracht gegeven om een vergelijkend bus emissie onderzoek te doen. VDL produceert lijn- en stadsbussen, die zijn uitgerust met dieselmotoren met EEV technologie. Het doel van deze opdracht is een vergelijk te maken tussen de VDL bus met diesel EEV technologie en andere bussen die zijn uitgerust met Euro III en IV diesel- of aardgasmotoren (EEV). De vergelijking betreft brandstofverbruik en uitlaatgasemissies (CO 2, deeltjes, NO x, CO en HC) DE VDL Ambassador SB 200 bus is ontwikkeld als stads- en streekbus. De bus is uitgerust met een Cummins 6.7 liter motor met SCR (Selective Catalytic Reduction) en CRT (Continuous Regenerating Trap) en voldoet aan EEV-limieten. De bus is geconstrueerd met lichtgewicht materialen en heeft een ledig gewicht van 8800 kg. Vanwege de vele verschillende voertuigconfiguraties wordt de typekeuringstest voor uitlaatgasemissies niet als voertuigtest uitgevoerd maar als motortest op een motorproefstand. Middels een ESC-test (European Steady state Cycle) en een ETC-test (European Transient Cycle) wordt een motor-gerelateerd patroon van toerental en belasting ingesteld en tegelijkertijd worden de uitlaatgas emissieniveaus gemeten. Over het algemeen zijn de uitlaatgasemissies geoptimaliseerd voor de ESC en ETC test. Praktijkgebruik van voertuigen is zeer complex en meestal wijken toerentalbelastingpatronen in de praktijk sterk af van de patronen in de ESC en ETC test. Vanwege deze afwijkingen kunnen de praktijkemissies verschillen van de verwachte emissies op basis van de typegoedkeuringsresultaten. Dit project is opgezet om de uitlaatgasemissies en het brandstofverbruik van de VDL Ambassador SB 200 bus onder specifieke busomstandigheden te meten. In het project zijn internationaal geaccepteerde testcycli voor bussen uitgevoerd. Op deze manier kunnen deze resultaten worden vergeleken met de resultaten van andere diesel- en aardgasbussen. De gebruikte testcycli zijn: Braunschweig cyclus voor typisch stadsbusgebruik, gemiddelde snelheid 22.5 km/h, maximum snelheid 58.2 km/h Helsinki 3 cyclus voor typisch streekbusgebruik, gemiddelde snelheid 41.2 km/h, maximum snelheid 71.7 km/h SORT3 cyclus, dit is een streekbuscyclus die ontwikkeld is door UITP (International association for public transport). De emissiemetingen en de vergelijkingen in dit project bevatten de volgende aspecten: Gereglementeerde componenten: Stikstofoxiden (NO x ), koolmonoxide (CO), koolwaterstoffen (HC) en fijn stof (ook wel roet, deeltjes of PM10 genoemd). Ongereglementeerde komponenten: Stikstofdioxide (NO 2 ) en koolstofdioxide (CO 2 )

34 TNO-rapport MON-RPT-033-DTS / 25 Deeltjesgrootteverdeling: metingen van deeltjesaantallen en deeltjesgrootte tussen 20 en 300 nanometer. De meetresultaten zijn vergeleken met meetresultaten van diesel- en aardgasbussen die eerder door VTT-Processes in Finland zijn gepubliceerd. VTT heeft het brandstofverbruik en emissiegedrag van aardgas- en dieselbussen in en [1,2] onderzocht. Om goed vergelijkbare met deze (door VTT gepubliceerde) data te hebben is dit meetprogramma ook bij VTT uitgevoerd. 1.2 Uitlaatgasemissie komponenten In dit hoofdstuk wordt een beknopt overzicht gegeven van de gereglementeerde en ongereglementeerde komponenten die in uitlaatgas voorkomen: Uitlaatgas bestaat o.a. uit de volgende komponenten: Gereglementeerde komponenten: Stikstofoxiden (NO x ), koolmonoxide (CO), koolwaterstoffen (HC) en fijn stof (PM10) Ongereglementeerde komponenten: Stikstofdioxide (NO 2 ), polycyclische aromaten (PAH), kooldioxide (CO 2 ), Distikstofoxide (N 2 O) en methaan (CH 4 ) Metaaloxiden afkomstig van smeerolie en motorslijtage Fijn stof Kooldioxide (CO 2 ) Kooldioxide wordt gevormd bij volledige verbranding van koolwaterstoffen. Dit gas draagt bij aan het broeikaseffect dat bijdraagt aan opwarming van de aarde (global warming). Fijn stof (PM10) Fijn stof bestaat uit een complex mengsel van organische en anorganische verbindingen. De grootte van deze deeltjes varieert tussen 20 tot 400 nm. De grootste deeltjesaantallen worden gemeten in het bereik van 20 tot 100 nm. Binnen de luchtkwaliteitsnormering bestaat de volgende verdeling: Grof > 2.5 micron. Fijn 0.1 tot 2.5 micron Ultra-fijn < 0.1 micron Stikstofoxiden Stikstofoxiden (NO x ) in uitlaatgas is een mengsel van NO en NO 2. NO 2 (stikstofdioxide) behoort tot een groep van uiterst reactieve gassen, de stikstofoxiden (NO x ). NO 2 is een van de belangrijkste luchtvervuilende komponenten in stedelijke gebieden. NO 2 is meer toxisch dan NO. NO kan ook door ozon omgezet worden in NO2. Vanwege dit aspect is NO 2 een belangrijk item in luchtkwaliteitsnormeringen. Distikstofoxide(N 2 O) Distikstofoxide draagt bij aan afbraak van ozon en wordt geproduceerd door oxidatiekatalysatoren. Koolmonoxide (CO) Koolmonoxide is een kleurloos, reukloos en giftig gas dat wordt geproduceerd bij onvolledige verbranding. De binding van koolmonoxide met haemoglobine dat COHb vormt, verminderd de transportcapaciteit van zuurstof in bloed en tast de

35 TNO-rapport MON-RPT-033-DTS / 25 zuurstofvrijgifte van haemoglobine aan waardoor de zuurstoflevering aan organen en weefsels verminderd. Polycyclische aromatische koolwaterstoffen (PAK) PAK bestaan uit een groot aantal komponenten die door een aantal bronnen worden uitgestoten. PAK die in lucht worden geformeerd bevatten komponenten die bij inhalatie longkanker kunnen veroorzaken. PAK is een grote groep komponenten die afkomstig zijn van brandstof en smeerolie; deze bestaan uit twee of meer ringvormige ketens die bestaan uit koolstof en waterstof. De fysische en chemische eigenschappen van individuele koolwaterstoffen variëren zeer sterk. PAK kan voorkomen in vluchtige, semi-vluchtige en vaste vorm. In uitlaatgas zijn vaste PAK gebonden aan koolstofdeeltjes. In dit meetprogramma zijn geen PAK metingen uitgevoerd. Methaan (CH 4 ) Methaan kan worden uitgestoten door aardgasvoertuigen en draagt in grote mate bij aan het broeikaseffect. In dit project zijn alleen gereglementeerde komponenten gemeten en vergeleken. Tevens zijn NO 2, CO 2 en deeltjes grootteverdelingsmetingen uitgevoerd.

36 TNO-rapport MON-RPT-033-DTS / 25 Onderzoeksopzet 2.1 Voertuigspecificatie De eigenschappen van de diesel- en aardgasbussen zijn vermeld in Tabel 1. De rijweerstandscurve van de VDL bus is afgeleid van vergelijkbare bussen (gelijke massa en gelijk bandentype) en is gecorrigeerd voor het frontoppervlak van het voertuig. De rolweerstand is gelijk verondersteld. De correctie voor het frontoppervlak heeft slechts een minimale invloed op de totale rijweerstandscurve. Tabel 1: Eigenschappen aardgas- en dieselbussen CNG bus Diesel bus VDL diesel bus Emissieklasse EEV Euro IV EEV Merk banden Michelin Michelin Goodyear Type banden XZA XZA Metro MCS Bandenmaat voor 275/70R /70R /70R19.5 Aantal voorbanden Bandenmaat achter 275/70R /70R /70R19.5 Aantal achterbanden Voertuighoogte [m] Voertuigbreedte [m] Frontoppervlak [m^2] Voertuigmassa onbeladen [kg] Voertuiglengte [m] Instellingen rollenbank Geabs. 10 km/h [kw] Geabs. 20 km/h [kw] Geabs. 30 km/h [kw] Geabs. 40 km/h [kw] Geabs. 50 km/h [kw] Geabs. 60 km/h [kw] Geabs. 70 km/h [kw] De rollenbankinstellingen voor de VDL bus zijn Belading Inertia [kg] F0 F1 F2 Onbeladen Half beladen Vol beladen SORT3 last

37 TNO-rapport MON-RPT-033-DTS / Motorspecificaties De VDL Ambassador bus is uitgerust met een Cummins dieselmotor die is voorzien van een SCR katalysator met AdBlue injectie en een CRT (oxidatiekatalysator met gesloten roetfilter, type wall-flow ). De motor voldoet aan EEV-emissielimieten. In Tabel 2 zijn de typegoedkeuringsresultaten vermeld. Deze emissies voldoen ruimschoots aan de EEV-limieten. De CO, THC en fijnstof emissies zijn 0-8% van de limietwaarde. De NO x -emissie is 25% onder de EEV-limietwaarde. Tabel 2: Cummins ISBe5 225B EEV dieselmotor Merk Cummins Type ISBe5 225B Slagvolume [dm 3 ] 6.7 Max. [kw] 2500 rpm Vermogen Max. Koppel [Nm] 1500 rpm ESC testresultaten EEV limiet Resultaat Percentage van limiet [g/kwh] [g/kwh] [%] CO HC NOx PM ETC test resultaat EEV limiet Resultaat Percentage van limiet [g/kwh] [g/kwh] [%] CO HC NOx PM Meetprogramma Het meetprogramma van de VDL Ambassador bus is uitgevoerd in september 2007 bij VTT Processes in Finland en is begeleid en gecontroleerd door TNO. Voorafgaand aan de metingen heeft uitgebreid overleg plaatsvevonden tussen VTT en TNO. Hierbij is speciaal aandacht gegeven aan het meetprogramma, de rijweerstandscurve en de meetprocedures. In de Tabellen 3 en 4 zijn de uitgevoerde testen gerapporteerd. De Braunschweig cyclus is een stadsbuscyclus. De Helsinki 3 en de SORT 3 cycli zijn aan te merken als streekbuscycli.