The impacts from cold start and road grade on real-world emissions and fuel consumption of gasoline, diesel and hybrid-electric light-duty passenger vehicles

Liqiang He; Yan You; Xuan Zheng; Shaojun Zhang; Zhenhua Li; Zikai Zhang; Ye Wu; Jiming Hao

doi:10.1016/j.scitotenv.2022.158045

The impacts from cold start and road grade on real-world emissions and fuel consumption of gasoline, diesel and hybrid-electric light-duty passenger vehicles

Sci Total Environ. 2022 Dec 10;851(Pt 1):158045. doi: 10.1016/j.scitotenv.2022.158045. Epub 2022 Aug 18.

Authors

Liqiang He¹, Yan You², Xuan Zheng³, Shaojun Zhang⁴, Zhenhua Li¹, Zikai Zhang², Ye Wu⁵, Jiming Hao⁴

Affiliations

¹ School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
² National Observation and Research Station of Coastal Ecological Environments in Macao, Macao Environmental Research Institute, Macau University of Science and Technology, Macao SAR 999078, China.
³ College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
⁴ School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China; Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China.
⁵ School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China; Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: ywu@tsinghua.edu.cn.

PMID: 35981594
DOI: 10.1016/j.scitotenv.2022.158045

Abstract

Progressively stringent regulations regarding vehicle emissions and fuel economy have spurred technology diversification in light-duty passenger vehicles (LDPVs). To assess the real-world emissions and fuel economy performances of hybrid electric vehicles (HEVs) compared to conventional internal combustion engine (ICE) vehicles, on-road measurements of ten gasoline, four diesel and six full hybrid LDPVs were performed using portable emissions measurement systems (PEMS) in Macao, China. The hot-running emission results indicate that the high emission risks of gasoline vehicles are associated with high mileage and old model years. Diesel vehicles are found to be the highest pollutant emitters in this study due to the intentional removal of aftertreatment systems. Under hot-running conditions, HEVs, as expected, could achieve carbon-reduction benefits of approximately 30 % (i.e., lower CO₂ emissions and fuel consumption) compared to their conventional gasoline counterparts, while no measurable reduction in pollutant emissions was observed except in NO_X (~70 % reduction). In contrast, the cold-start extra emissions (CSEEs) of CO₂ reached 120-364 g/start for these HEVs, even exceeding the maximum values of conventional gasoline vehicles. However, the higher CO₂ CSEEs of HEVs can be far offset by their hot-running emission reduction benefits. For tailpipe pollutants, the CSEEs of the HEVs were reduced by 21 %-68 % on average in comparison to those of conventional gasoline vehicles. Furthermore, strong correlations (R² values of 0.69-0.89) between the road grades and relative emissions were observed. These results can provide necessary information regarding the improvement of future LDPV emission models and inventories.

Keywords: Cold start; Hybrid electric vehicle (HEV); Light-duty passenger vehicle (LDPV); Real driving emissions (RDE); Road grade.

MeSH terms

Air Pollutants* / analysis
Carbon
Carbon Dioxide / analysis
Gasoline* / analysis
Motor Vehicles
Vehicle Emissions / analysis

Substances

Air Pollutants
Gasoline
Vehicle Emissions
Carbon Dioxide
Carbon