Strategies for improving the emission performance of hybrid electric vehicles

• Published in: The Science of the total environment 2021-06, Vol.771, p.144901-144901, Article 144901
• Main Authors: Bagheri, S., Huang, Y., Walker, P.D., Zhou, J.L., Surawski, N.C.
• Format: Article
• Language: English
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.144901

Low emission vehicle technologies need widespread adoption in the transport sector to overcome its significant decarbonisation challenges. Hybrid Electric Vehicles (HEVs) represent an intermediate technology between pure electric vehicles and internal combustion engines that have proven capability in reducing petroleum consumption. HEV customers often cite improved fuel economy as a major benefit from adopting this technology; however, outstanding questions remain regarding their respective emission levels. Through an extensive literature study, we show that several issues remain with HEV emissions performance which stem from frequent high-power cold starts, engine calibration issues and inefficient operating conditions for catalytic converters. HEVs have more NOx, HC, CO and particle number emissions compared to conventional vehicles by up to 21.0, 5.8, 9.0 and 23.3 times, respectively. Improved engine control algorithms, after-treatment design and thermal design of three-way catalysts emerge as research priorities for improving the emissions performance of HEVs. [Display omitted] •Uncertainties present in emission levels from hybrid electric vehicles•Literature review conducted to compare conventional and hybrid vehicle emissions•Thirteen studies compared conventional and hybrid vehicle emissions•Emission increases ranged from 5.8-fold for HCs to 23.3-fold for PN.•Improved engine calibration, thermal and after-treatment systems lowered emissions