08 MAY 2025 (THU) 11:35-11:55

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

Mr CHEUK Sung Ho 

( Supervisor: Prof Nicky Y.F. Lam )

Abstract:

Electrifying private vehicles (PVs) has become a significant global trend to combat greenhouse gas emissions (GHG). Although electric vehicles (EVs) can decarbonise land transport, 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 is 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 carbon emissions; 3) and the strategies for implementing green H2 in EGM and PV fleets to achieve optimal decarbonisation effects for EVs and hydrogen fuel cell vehicles (HFCVs).

The co-benefit of anti-idling policies in Hong Kong and other cities in the Greater Bay Area (GBA) is first examined. Through an online questionnaire consisting of 200 local PV drivers, the idling behaviour patterns of local drivers are obtained to estimate the carbon reduction of anti-idling policies. Hong Kong's idling emissions are projected to decrease from 8,151 to 5,133 tons from 2012-50, despite a diminishing anti-idling policy's effectiveness from 50% to zero due to an increasing emission leak from EVs. Although PV population is projected to increase by 40% from 2012-2035, GBA's total idling emissions will decrease from 357,403 to 305,548 tons after EGM reform and PV electrification.

By integrating the idling and travelling data, the total emissions for Hong Kong, Singapore, Luxembourg, Oslo, and Vermont are estimated from 2012-50. Luxembourg is predicted to emit the highest amount of CO2e (220 kt) because it does not intend to phase out fuel PVs. 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 carbon emissions than the global cities. In particular, the CO2e emissions are primarily a result of the high number of PVs and fossil-based EGM in the Eastern provinces.

Under a "supply-demand-policy" model, a VIKOR-Analytical Hierarchical Process decision- making method is used to evaluate the development potential of green hydrogen 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 hydrogen deployment strategies is also provided. While green hydrogen in electricity generation increases the EGM emission factor by 30 gCO2e/kWh under energy loss, HFCVs fueled by green hydrogen reduce carbon dioxide emissions 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.