Driving towards sustainability : a longitudinal study on the interplay between electric vehicles and electricity generation mix

Abstract

Electrifying private vehicles (PVs) has become a significant global trend to combat roadside air pollution and greenhouse gas (GHG) emissions. Although electric vehicles (EVs) decarbonise a considerable amount of energy, they are hampered by fossil-dominated electricity generation mixes (EGMs) in most countries, as their GHG emissions are diverted to fossil-fueled power plants. Although research has been conducted on vehicle emissions and EGMs, there are still 1) a lack of idling behavioural data to estimate the co-benefit of anti-idling policy regarding decarbonisation in the era of EVs; 2) a longitudinal comparison and projection of the evolving interaction between PVs and EGMs among global cities regarding CO2e emission; 3) and the strategies for implementing green hydrogen in EGM and PV fleets to achieve optimal decarbonisation effects for EVs and hydrogen fuel cell vehicles (HFCVs). As a starting point, this thesis examined the co-benefit of anti-idling policies in Hong Kong and other cities in the Greater Bay Area (GBA). Through the online distribution of a questionnaire to 200 local PV drivers, the idling behaviour patterns of local drivers were obtained to estimate the carbon reduction of anti-idling policy. It has been determined that Hong Kong's idling emissions will decrease from 8,151 to 5,133 tonnes from 2012 to 2050, despite a diminishing anti-idling policy's effectiveness from 50% to zero due to an increasing emission leak from EVs. In spite of the fact that the PV population is projected to increase by 40% from 2012-2035, GBA's total idling emissions are projected to decrease from 357,403 to 305,548 tonnes after the reform of the EGM and PV electrification. By integrating the idling behavioural data with the driving data, the total emissions for Hong Kong, Singapore, Luxembourg, Oslo, and Vermont were evaluated for 2012 - 2050. Luxembourg is predicted to emit the highest amount of CO2e (220 kt) because it does not intend to phase out fuel PVs. At the same time, Vermont, in contrast, will achieve the greatest decarbonisation (2,800 kt reduction) due to EV popularisation and the implementation of carbon-free EGMs. However, owing to China’s large PV population and coal-dominated EGM, China has far more CO2e emission than the global cities. In particular, the CO2e emission is primarily a result of the high number of PVs and fossil-based EGMs in the Eastern provinces. Under a "supply-demand-policy" model, a VIKOR-Analytical hierarchical process decision-making method was used to evaluate the development potential of green hydrogen (H2) in China. Despite its well-established infrastructure and economic prosperity, the East has the highest potential for development, while the West has greater renewable energy capacity. A comparison of the decarbonisation effects of green H2 deployment strategies is also provided. While green H2 in electricity generation increases the EGM emission factor by 30 gCO2e/kWh under energy loss, HFCVs fueled by green H2 reduce CO2e emission by 9-64% compared to EVs. Using the datasets and translational equations developed in this thesis, international policymakers may be inspired to reform their EGMs and PV fleet mix to achieve carbon neutrality and combat global warming.