Thesis title: Integrating uncertainty into the decarbonization of the transport sector: new tools and strategies for policy and decision makers
The decarbonization of the transport sector stands as one of the most critical challenges in achieving global climate goals. However, the ecological transition of both public and private mobility is constrained by deep technological, economic, and policy uncertainties. Despite major advances in clean propulsion technology and energy systems, the transport sector remains one of the largest contributors to greenhouse gas emissions worldwide, responsible for nearly a quarter of global CO₂ output. While renewable energy deployment and electrification are progressing, their diffusion across transport systems is uneven and strongly dependent on infrastructure readiness, regulatory frameworks, and consumer acceptance.
In public transport sector, among alternative powertrains, battery electric buses (BEBs) currently represent the most promising option for reducing emissions. Their economic and environmental potential is growing, yet their actual convenience remains uncertain and strongly context dependent. BEBs face high initial costs and infrastructure-related uncertainties that still limit large-scale deployment. Future improvements in costs and performance are expected, but both their pace and magnitude remain unpredictable. Operators often postpone fleet replacement while waiting for clearer incentives or more mature technologies, yet excessive delay risks slowing down the transition itself. At the same time, private mobility remains the largest contributor to transport-related emissions and a major obstacle to achieving full decarbonization. The uptake of electric vehicles (EVs) is accelerating, but its pace and distribution across countries are highly uneven. Adoption is strongly shaped by fiscal policies and energy generation mix. Even as upfront costs decrease, users remain strongly responsive to taxation and incentives, however the magnitude of this response is still highly uncertain.
This thesis investigates how uncertainty shapes the ecological transition of public and private transport and how governments and decision makers can design strategies that remain effective under changing conditions. It examines investment choices and fiscal measures through complementary analytical approaches that combine economics, risk analysis and decision theory. The central argument is that deterministic models still dominate transport appraisal and planning, despite their inability to capture the depth and persistence of uncertainty in real-world transitions.
The research first analyses how current academic and professional practice evaluate investments in transport decarbonization. A systematic examination of the literature reveals that most studies neglect uncertainty or treat it superficially, relying on fixed assumptions about costs, technological performances and user behavior. This critical evidence motivates the development of new quantitative tools that explicitly model risk and flexibility in decision making, like Real Options (RO) analysis.
Building on this foundation, the thesis develops RO frameworks to analyze how decision makers and policy makers can manage technological uncertainty and identify optimal strategies for fleet replacement and public support in the transition toward zero-emission busses, especially BEBs. The approach captures the value of flexibility and the importance of timing in investment and policy decisions, showing how uncertainty can be transformed from a source of risk into a strategic element for improving efficiency. By integrating stochastic modelling with economic evaluation, the analysis provides a perspective on how operators can plan fleet renewal under evolving conditions and how governments can design adaptive policies that accelerate decarbonization while containing financial exposure.
The analysis then extends to the private mobility sector, examining how uncertainty also influences the design of fiscal instruments for electric vehicles. It finds that taxations (or incentives) can ensure fairness and financial sustainability only if they adapt to evolving market conditions, intrinsically uncertain behavioral responses and geographical differences between urban and rural contexts.
The thesis ultimately shows that uncertainty is not an external disturbance but the defining feature of the ecological transition. Recognizing it and acting upon it transforms both policy making and strategic investment from reactive to forward looking. In this perspective, embracing uncertainty enables governments and decision makers to design resilient incentives, allocate resources more efficiently and guide the parallel decarbonization of public transportation and private mobility. The results suggest that future transport policies and investment strategies should replace static evaluations with adaptive frameworks capable of learning and evolving alongside technological and societal change.