| 1. |
- Haeger-Eugensson, Marie, et al.
(författare)
-
On the increasing levels of NO2 in some cities. The role of primary emissions and shipping
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is an attempt to investigate the background to the high NO2 levels in Gothenburg and the reason for the slowing decrease in NO2 observed during the last years. Two possible reasons for these observations are investigated: contribution from shipping to NO2 emissions, and increased fraction of NO2 in the NOX emissions from modern diesel engines. The issue was studied through emission measurement, passive sampling, dispersion modelling and atmospheric chemistry studies Two possible reasons for the high NO2 levels in Gothenburg were investigated: 1) increased fraction of NO2 in the NOX emissions from modern diesel engines, and 2) increasing total emission of NOX due to increasing contribution from shipping. The results also showed that local mixing conditions greatly influenced the dispersion of especially local and ground-based emissions This was mainly due to their main location within the Göta älv valleys where the dispersion becomes particularly poor during high pressure conditions. The effect of ship emissions in the Gothenburg area was very dominant along the harbour. At distances of about 1-2 km fromthe harbour area the ship contribution was still more than 30 % of the total NOX concentration level. The modelled concentration data was compared to measurement results from passive sampling performed mainly along the river but also with the continuous monitoring at the Femman site. In general, the NO2 concentrations were underestimated, the SO2 mainly coincided well and the O3 concentrations where somewhat overestimated in the calculations with the TAPM model. Variation in concentrations due to varying weather conditions were reproduced well but the modelled peaks are sometimes lower than the monitored concentration peaks. There are several explanations for the increased proportions of NO2 in the primary emissions of NOX. First the increase in the fraction of diesel vehicles by ca. 15% (as vehicle-km) during the last decade. Diesel vehicles generally have a higher fraction of NO2 in their NOX emissions than gasoline cars. On top of this, the large increase of diesel vehicles over the last decade was accompanied by a simultaneous increase of the NO2 fraction in NOX emissions from diesel trucks with Euro3 and Euro4 standards which became compulsory in 2000 and 2005, respectively. Measurements of NO2 and NOX concentrations in tunnels, and at sites largely dominated by primary emissions, indicated an increase in the NO2/NOX partitioning from 4-6% in the 1980s, and at the beginning of the 1990s, to today's 13%. The tunnel-model study indicated that the actual NO2/NOX fraction could be even larger if effects of the NO2 sinks in the tunnel are taken into account. The modelling results show that the increase in the NO2 share of the NO2 concentrations was greatest close to the sources since the NO in the primary emission reacted with ambient ozone forming NO2 on a time-scale of minutes and the NO2/NOX ratio quickly increased, approaching a photo-stationary state between NO, NO2 and ozone. The simultaneous measurements of NO2, NO (or NOX) and ozone indicated that the fraction of primary and secondary NO2 in the city varied largely depending on mixing and photochemical conditions. A sensitivity study with the city scale dispersion model was performed by raising the NO2/NOX emission ratio from 5 to 20%. The change in NO2 concentrations showed that the effect of the higher share of NO2 within the NOx emissions can affect the NO2 concentration level close to the source up to a distance of about 500-700m. The chemical development in ship plumes was studied with a detailed photochemical plume model to ensure that the simple chemistry treatment of the TAPM model accurately described the processes affecting the NO/NO2 distribution and NOX oxidation. Comparison of the detailed chemistry with the simplified version showed a significant similarity during day hours when chemistry is, to a large extent, driven by NO2 photolysis. The night-time chemistry of NOX, driven by nitrate radical and oxidation of N2O5 is not included in the TAPM chemical scheme which may lead to an underestimation of NOX oxidation during dark hours.
|
|
| 2. |
|
|
| 3. |
- Fridell, Erik, et al.
(författare)
-
Crossing Borders and Expanding Modal Shift Measures: Effects on Mode Choice and Emissions from Freight Transport in the Nordics
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:3, s. 894-
-
Tidskriftsartikel (refereegranskat)abstract
- Considering the underachievement on modal shift and environmental objectives for freight transport, scholars and policy makers recurrently ask how more road freight can be shifted to rail and waterborne transport. The current study simulates transport and modal distribution effects for several scenarios in which modal shift policy measures are strengthened, expanded, combined, and harmonized across borders in the Nordics. Found transport effects were then used in an environmental model to assess implications for energy use and emissions of CO2,eq, NOx, and particulate matter, gaining insights into which policy measures are more effective or complement each other, and whether international harmonization might increase effectiveness, and modal shift. From our simulations, a Norwegian ecobonus scheme for rail yields larger modal shift away from road than a similar ecobonus for sea transport. Facilitating longer freight trains yields more modal shift but has high policy costs. Effects of harmonizing policies across Nordic countries vary but can be strengthened by combining different measures. However, even for scenarios with strong policy measures, reductions in CO2,eq emissions do not exceed 3.6% in 2030 while sometimes increasing local air pollution. Modal shift policy should therefore not exclusively be regarded as environmental strategy, although it may contribute to other policy objectives.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Hallquist, Åsa M., et al.
(författare)
-
Particle and gaseous emissions from individual diesel and CNG buses
- 2013
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 13:10, s. 5337-5350
-
Tidskriftsartikel (refereegranskat)abstract
- In this study size-resolved particle and gaseous emissions from 28 individual diesel-fuelled and 7 compressed natural gas (CNG)-fuelled buses, selected from an in-use bus fleet, were characterised for real-world dilution scenarios. The method used was based on using CO2 as a tracer of exhaust gas dilution. The particles were sampled by using an extractive sampling method and analysed with high time resolution instrumentation EEPS (10 Hz) and CO2 with a non-dispersive infrared gas analyser (LI-840, LI-COR Inc. 1 Hz). The gaseous constituents (CO, HC and NO) were measured by using a remote sensing device (AccuScan RSD 3000, Environmental System Products Inc.). Nitrogen oxides, NOx, were estimated from NO by using default NO2/NOx ratios from the road vehicle emission model HBEFA3.1. The buses studied were diesel-fuelled Euro III–V and CNG-fuelled Enhanced Environmentally Friendly Vehicles (EEVs) with different after-treatment, including selective catalytic reduction (SCR), exhaust gas recirculation (EGR) and with and without diesel particulate filter (DPF). The primary driving mode applied in this study was accelerating mode. However, regarding the particle emissions also a constant speed mode was analysed. The investigated CNG buses emitted on average a higher number of particles but less mass compared to the diesel-fuelled buses. Emission factors for number of particles (EFPN) were EFPN, DPF = 4.4 ± 3.5 × 1014, EFPN, no DPF = 2.1 ± 1.0 × 1015 and EFPN, CNG = 7.8 ± 5.7 ×1015 kg fuel−1. In the accelerating mode, size-resolved emission factors (EFs) showed unimodal number size distributions with peak diameters of 70–90 nm and 10 nm for diesel and CNG buses, respectively. For the constant speed mode, bimodal average number size distributions were obtained for the diesel buses with peak modes of ~10 nm and ~60 nm. Emission factors for NOx expressed as NO2 equivalents for the diesel buses were on average 27 ± 7 g (kg fuel)−1 and for the CNG buses 41 ± 26 g (kg fuel)−1. An anti-relationship between EFNOx and EFPM was observed especially for buses with no DPF, and there was a positive relationship between EFPM and EFCO.
|
|
| 7. |
|
|
| 8. |
- Jerksjö, Martin, et al.
(författare)
-
Avgasmätningar på bussar i verklig drift för identifiering av högemitterare
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Inom ramen för ett forskningsprojekt samfinansierat av Västtrafik och Stiftelsen IVL har IVL under 2011 och 2012 genomfört avgasmätningar på ett hundratal bussar i Västsverige. Avgasmätningarna utfördes utomhus på gårdsplanerna hos de bussoperatörer där bussarna testats. Avgaserna mättes från varje buss när de vid upprepade tillfällen passerade mätutrustningen under fullgas¬acceleration. För att inte behöva ta hänsyn till utspädningen med luften mättes alla utsläpp relativt CO2 eftersom förhållandet till CO2 förblir konstant oberoende av utspädningen. Resultaten rapporteras som föroreningarnas massa per kilo förbrukat bränsle. I syfte att validera de vägkantsbaserade utsläppsmätningarna utfördes även inom projektet ombordmätningar på en buss (Euro V) med PEMS (Portable Emission Monitoring System). PEMS-mätningarna syftade även till att undersöka hur de uppmätta utsläppen under acceleration relaterar till utsläppen under körning i linjetrafik med en blandning av körning i stads- och landsbygdstrafik. Utifrån ombordmätningarna har för partiklar kunnat uppskattas gränsvärden på utsläpp under fullgasacceleration, vilka kan användas som indikation på att bussar vars utsläpp överskrider detta värde inte uppfyller de lagkrav de är certifierade mot. Bland annat till följd av den stora inverkan avgastemperaturen har på NOX-reningen hos Euro IV och Euro V bussar med SCR-katalysator, har motsvarande gränsvärden inte kunnat uppskattas för utsläpp av kväveoxider. Då bussar med olika drivmedel ingått i mätningarna har även drivmedlets inverkan på utsläppen kunnat studeras. Detta har dock främst varit möjligt för utsläpp av partiklar. När det gäller utsläpp av kväveoxider har det i de flesta fall inte gått att bedöma i vilken grad variationer i utsläpp berott på vilket bränsle som använts eller på otillräcklig reningsfunktion hos SCR-systemet till följd av för låg avgastemperatur. Om den vägkantsbaserade avgasmätmetoden ska kunna användas för att bedöma utsläpps-prestanda med avseende på kväveoxider i relation till gällande avgaskrav för bussar som är certifierade att klara Euro IV och Euro V kraven och som har SCR-katalysator, måste man försäkra sig om att avgastemperaturen vid mättillfället är tillräckligt hög för att SCR-systemet ska fungera optimalt. Detta är möjligt att uppnå om mätplatsen väljs så att mätningarna kan utföras i direkt anslutning till att bussen kommit från körning på landsväg eller motorväg.
|
|
| 9. |
- Jerksjö, Martin, et al.
(författare)
-
Comparing emission rates derived from remote sensing with PEMS and chassis dynamometer tests - CONOX Task 1 report
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report a newly developed method is presented to enable improved comparisons of emission results from remote sensing measurements with those from PEMS routes or from chassis dynamometer standard driving cycles, which together will help to corroborate measurements and better understand real-driving emissions of in particular NOX from late model diesel light-duty vehicles, e.g. Euro 5 and Euro 6 passenger cars. The method utilizes information and data commonly available from remote sensing measurements, such as speed, acceleration and road grade, together with crucial vehicle information, such as vehicle segment, engine/fuel type and Euro classification. From this information the vehicle specific power (VSP) is calculated on an individual vehicle level, which is used as input to simulations with the TU Graz PHEM model to derive instantaneous fuel rates on an individual or aggregated vehicle level. The derived fuel rates are used to convert emissions expressed as gram pollutant emitted per kg fuel burned from the remote sensing measurements into gram pollutant emitted per vehicle distance driven (e.g. g/km). By dividing large remote sensing datasets into VSP bins, the proposed method can be used to convert remote sensing emission rates to any test cycle, such as the WLTP, for further comparisons.
|
|
| 10. |
- Jerksjö, Martin, et al.
(författare)
-
Measurements of bus emissions 2010-2015
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report results from measurements of exhaust emissions from buses conducted by IVL between 2010 and 2015 are presented. The measurements are parts of three different studies of which the latest was conducted between 2014 and 2015. The measured emissions from all studies form a relatively large data set, which may be used for various analyses. This is the reason why IVL has chosen to present results from all three studies in this report, even if the focus lies on the latest study. The main objectives of the latest study were to: • measure emissions from Euro VI buses. • measure both NO (nitrogen oxide) and NO2 (nitrogen dioxide) and not only NO which was the case in the previous studies. • measure emissions from buses driving in real world traffic and not only during controlled conditions as was the case in the previous studies. In this report emissions of nitrogen oxides (NOX), carbon monoxide (CO) and particle mass (PM) are presented. The emissions have been analysed with respect to Euro class, exhaust aftertreatment and fuel type. The most important findings were: • The average emissions of NOX and particles from the tested Euro VI buses are significantly lower than from the tested Euro V buses. • The median particle emission from Euro V buses driving on 100% RME (Rapeseed Methyl Esther) was 88% lower compared to buses driving on (low blended) diesel. This result is based on measurements of buses from only one manufacturer. • The median nitrogen oxide emission from Euro V buses driving on 100% RME was 35% higher compared to buses driving on (low blended) diesel. This result is based on measurements on buses from only one manufacturer. However, the difference of the average values was not statistically significant. • No decrease in NOX emissions was observed going from Euro III to Euro V. • A constant decrease of particle emissions (by mass) was observed going from Euro III to Euro VI, with the exception of Euro IV buses using EGR. • Measured average NO2 share of NOX is in relatively good accordance with data from the road vehicle emission model HBEFA. However, the results indicate that the ratio is not only dependent on the Euro standard and the exhaust aftertreatment system but also on vehicle manufacturer. • Three out of the six buses which were tested fuelled with both (low blended) diesel and 100% RME did show a reduction of particle emissions when fuelled with RME. The remaining three buses showed an increase in PM emissions and a simultaneous increase in CO emissions. Den här rapporten finns endast på engelska. Svensk sammanfattning finns i rapporten.
|
|
