Real-driving Emission Performance and Potential Reduction from Vans

Vans are a major contributor to NOx emissions and CO2 emissions in the road transport sector in Great Britain, however little attention is given to vans compared with passenger cars. The work aims to provide an accurate estimation of real-world NOx and CO2 emissions of the van fleet, explore how the external factors would affect the NOx emission performance of vans, develop a reliable evidence-based knowledge of the van fleet composition and use, and project the future van emission pathways under different scenarios. Firstly, the real-world emission performance of vans is assessed by the instantaneous vehicle emission model PHEM and remote sensing measurements. The validated emission model PHEM is used to simulate the real-world CO2 and NOx emissions from standard vans and refrigerated vans. Then the Gumbel distribution is introduced to remote sensing measurements to have a robust description of fleet-wide NOx emissions from vans and identify candidate high-emitting vehicles. Secondly, the uncertainty associated with real-world NOx emission estimation is evaluated. Simulation results by PHEM and remote sensing measurements are used to analyse the impact of ambient conditions (e.g., road grade, ambient temperature), driving conditions (e.g., speed and acceleration) on tailpipe emissions of vans. The impact of various NOx control-systems is also considered. At last, the future emission trend in the van sector in Great Britain is estimated. Several scenarios are designed to identify the key factors influencing emission reduction speed. This thesis validates PHEM’s ability to provide representative real-world CO2 and NOx emissions from vans, introduces the Gumbel distribution to remote sensing measurements to provide a more relevant description of fleet NOx emissions and identify candidate high emitters, and suggests that a fast transition to battery electric vehicles in the early 2020s will show significant benefit with regard to the CO2 emission mitigation in the van sector.