Implications of diesel emissions control failures to emission factors and road transport NOx evolution

Ntziachristos, Leónidas; Papadimitriou, Giannis; Ligterink, N.E.; Hausberger, Stefan

doi:10.1016/j.atmosenv.2016.07.036

Cited by 78 publications

(57 citation statements)

References 8 publications

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“…EFs for passenger cars within the inventory guidebook were experimentally obtained from laboratory tests in the context of large scientific programs in Europe (ARTEMIS, MEET projects). Despite the fact that the EFs in the guidebook were obtained using realistic test cycles, emission modellers in Europe claim that emission inventories need to take into account not only laboratory measurements but also real-world observations [14,15] since many studies have found differences in the emissions between real-world and laboratory conditions [16,17].…”

Section: Introductionmentioning

confidence: 99%

Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements

et al. 2019

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Tailpipe emissions of a pool of 13 Euro 6b light-duty vehicles (eight diesel and five gasoline-powered) were measured over an extensive experimental campaign that included laboratory (chassis dynamometer), and on-road tests (using a portable emissions measurement system). The New European Driving Cycle (NEDC) and the Worldwide harmonised Light-duty vehicles Test Cycle (WLTC) were driven in the laboratory following standard and extended testing procedures (such as low temperatures, use of auxiliaries, modified speed trace). On-road tests were conducted in real traffic conditions, within and outside the boundary conditions of the regulated European Real-Driving Emissions (RDE) test. Nitrogen oxides (NO X ), particle number (PN), carbon monoxide (CO), total hydrocarbons (HC), and carbon dioxide (CO 2 ) emission factors were developed considering the whole cycles, their sub-cycles, and the first 300 s of each test to assess the cold start effect. Despite complying with the NEDC type approval NO X limit, diesel vehicles emitted, on average, over the WLTC and the RDE 2.1 and 6.7 times more than the standard limit, respectively. Diesel vehicles equipped with only a Lean NO X trap (LNT) averaged six and two times more emissions over the WLTC and the RDE, respectively, than diesel vehicles equipped with a selective catalytic reduction (SCR) catalyst. Gasoline vehicles with direct injection (GDI) emitted eight times more NO X than those with port fuel injection (PFI) on RDE tests. Large NO X emissions on the urban section were also recorded for GDIs (122 mg/km). Diesel particle filters were mounted on all diesel vehicles, resulting in low particle number emission (~10 10 #/km) over all testing conditions including low temperature and high dynamicity. GDIs (~10 12 #/km) and PFIs (~10 11 #/km) had PN emissions that were, on average, two and one order of magnitude higher than for diesel vehicles, respectively, with significant contribution from the cold start. PFIs yielded high CO emission factors under high load operation reaching on average 2.2 g/km and 3.8 g/km on WLTC extra-high and RDE motorway, respectively. The average on-road CO 2 emissions were~33% and 41% higher than the declared CO 2 emissions at type-approval for diesel and gasoline vehicles, respectively. The use of auxiliaries (AC and lights on) over the NEDC led to an increase of~20% of CO 2 emissions for both diesel and gasoline vehicles. Results for NO X , CO and CO 2 were used to derive average on-road emission factors that are in good agreement with the emission factors proposed by the EMEP/EEA guidebook.

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Section: Introductionmentioning

confidence: 99%

Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements

et al. 2019

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“…This new driving cycle ensures a nationwide comparability of test procedures but includes no on-road tests (DELPHI 2017). In a different approach, real-world emissions from diesel cars and cars with spark-ignition engines are measured by Portable Emission Measurement Systems (PEMS) (Weiss et al 2011;Kousoulidou et al 2013;Ntziachristos et al 2016). Several PEMS studies have shown that the Euro emission standards are frequently exceeded, especially the latest standard Euro 6 (Weiss et al 2012;Franco et al 2014;O'Driscoll et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Real-world vehicle emissions as measured by in situ analysis of exhaust plumes

Peitzmeier

Loschke

Wiedenhaus

et al. 2017

Environ Sci Pollut Res

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We conducted a 60-day roadside measurement campaign on a busy street in Münster, Germany, during summer 2016. We used gas and particle concentration measurements with high temporal resolution (10 Hz) to quantify both the emission ratios of nitrogen oxides per carbon dioxide (NO x /CO 2 ) for over 70,000 individual exhaust plumes as well as the emission ratios for size-resolved particle numbers per carbon dioxide (d(PN CO 2 −1 )/dlogD) for about 10,000plumes. The real-world fleet passing by the measurement station consisted of passenger cars (85%), buses (5.9%), light duty commercial vehicles (5.7%), trucks (1.7%), and motorcycles (1.6%). The median measured NO x /CO 2 ratio was 3.33 g kg −1 . The median measured PN/CO 2 emission ratio for particles with diameters between 0.03 and 10 μm was 5.6 × 10 14 kg −1 . We compared our results with the Handbook Emission Factors for Road Transport (HBEFA) and the Euro 5 and Euro 6 emission standards by employing traffic counts, assuming the diesel-to-gasoline ratios of vehicles according to registration statistics, and estimating that stop-and-go traffic occurred 65% of the time. Using a conservative estimate, our median ratios exceeded the HBEFA data by more than 65% for NO x /CO and by a factor of about 100 for PN/CO 2. Furthermore, our median NO x emission per kilometer travelled (NO x km −1 ) exceeded the Euro 5 emission limit for diesel cars by a factor of 3 and exceeded the Euro 6 limit by almost a factor of 7. Additionally, our median particle number emission (PN km −1 ) exceeded the Euro 5 and Euro 6 limits of diesel cars by a factor of almost 150. These results confirm the presumption that the emissions of a real-world traffic fleet comprehensively exceed the legal limits. Very likely, the widespread presence of defeat devices in vehicle emission control systems plays a major role in this discrepancy. This has a strong impact on the apparent inability of authorities to comply with the legal limits of the NO 2 concentrations in urban air.

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“…While light duty diesel-powered vehicles (diesel vehicles, thereafter) certified to most recent emission standards have been found to effectively reduce emissions of particulate matter (PM), several studies over the past years have pointed to failures to meet the NO x emission standards under real-world driving conditions [1][2][3][4][5][6][7][8][9][10][11][12][13]. A particularly serious case is the recent revelation of defeat devices installed in diesel vehicles of companies including Volkswagen (VW), Audi, and Porsche (collectively VW thereafter), socalled Dieselgate [14].…”

Section: Introductionmentioning

confidence: 99%

Climate effects of non-compliant Volkswagen diesel cars

Tanaka

Lund

Aamaas

et al. 2018

Environ. Res. Lett.

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On-road operations of Volkswagen light-duty diesel vehicles equipped with defeat devices cause emissions of NO x up to 40 times above emission standards. Higher on-road NO x emissions are a widespread problem not limited to Volkswagen vehicles, but the Volkswagen violations brought this issue under the spotlight. While several studies investigated the health impacts of high NO x emissions, the climatic impacts have not been quantified. Here we show that such diesel cars generate a larger warming on the time scale of several years but a smaller warming on the decadal time scale during actual on-road operations than in vehicle certification tests. The difference in longer-term warming levels, however, depends on underlying driving conditions. Furthermore, in the presence of defeat devices, the climatic advantage of 'clean diesel' cars over gasoline cars, in terms of global-mean temperature change, is in our view not necessarily the case.

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Implications of diesel emissions control failures to emission factors and road transport NOx evolution

Cited by 78 publications

References 8 publications

Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements

Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements

Real-world vehicle emissions as measured by in situ analysis of exhaust plumes

Climate effects of non-compliant Volkswagen diesel cars

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