Imperial College London
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Dr Marc Stettler

Faculty of Engineering, Department of Civil and Environmental Engineering

Reader in Transport and the Environment
 
 
 
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Contact

 

+44 (0)20 7594 2094m.stettler Website

 
 
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Location

 

614Skempton BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Phantawesak:2022:10.1021/acs.est.1c05083,
author = {Phantawesak, N and Coyle, F and Stettler, M},
doi = {10.1021/acs.est.1c05083},
journal = {Environmental Science and Technology (Washington)},
pages = {6968--6977},
title = {Long-term in-use NOx emissions from London buses with retrofitted NOx aftertreatment},
url = {http://dx.doi.org/10.1021/acs.est.1c05083},
volume = {56},
year = {2022}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Buses constitute a significant source of air pollutant emissions in cities. In this study, we present real-world NOx emissions from 97 diesel-hybrid buses measured using on-board diagnostic systems over 44 months and 6.35 million km in London. Each bus had previously been retrofitted with a selective catalytic reduction (SCR) aftertreatment system to reduce emissions of nitrogen oxides (NOx). On average, parallel hybrid (PH) and series hybrid (SH) buses emitted 3.80 g of NOx/km [standard deviation (SD) of 1.02] and 2.37 g of NOx/km (SD of 0.51), respectively. The SCR systems reduced engine-out emissions by 79.8% (SD of 5.0) and 87.2% (SD of 2.9) for the PHs and SHs, respectively. Lower ambient temperatures (0–10 °C) increased NOx emissions of the PHs by 24.2% but decreased NOx emissions of the SHs by 27.9% compared to values found at more moderate temperatures (10–20 °C). To improve emissions inventories, we provide new distance-based NOx emissions factors for different ranges of ambient temperature. During the COVID-19 pandemic, the emissions benefits of reduced congestion were largely offset by more frequent route layovers leading to lower SCR temperatures and effectiveness. This study shows that continuous in-service measurements enable quantification of real-world vehicle emissions over a wide range of operations that complements conventional testing approaches.
AU  - Phantawesak,N
AU  - Coyle,F
AU  - Stettler,M
DO  - 10.1021/acs.est.1c05083
EP  - 6977
PY  - 2022///
SN  - 0013-936X
SP  - 6968
TI  - Long-term in-use NOx emissions from London buses with retrofitted NOx aftertreatment
T2  - Environmental Science and Technology (Washington)
UR  - http://dx.doi.org/10.1021/acs.est.1c05083
UR  - http://hdl.handle.net/10044/1/92704
VL  - 56
ER  -
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