Insights from Energy Systems Optimization Models and Stakeholders Engagement – A Multi-Scale and Cross-Sectoral Perspective on Low-Carbon Transport Systems

Doktorsavhandling, 2026

While energy transition literature often describes such a transition as a context-specific process, this perspective is frequently overlooked in studies of low-carbon transport systems. This thesis addresses this research gap, by developing a single analytical framework that considers (i) a multi‑scale perspective; (ii) cross‑sectoral interactions; and (iii) a continuous soft‑link between energy systems optimization models (ESOMs) and stakeholders engagement. The framework considers local (urban and non‑urban), national, and global scales, and examines low‑carbon transport transition under both exogenous and endogenous cross‑sectoral perspectives.

The results show that low‑carbon transport pathways are context-dependent, varying not only across spatial scales, but also socio‑geographical contexts. For passenger cars, all scenarios converge toward increased electrification in the long term; however, the pace and cost‑optimal technology pathways are influenced by travel behavior, infrastructure availability, and policy constraints. A multi‑scale perspective further reveals that aggregated national results tend to reflect urban dynamics, potentially overlooking non‑urban transport systems’ dynamics.

Adopting a cross‑sectoral perspective demonstrates that transport transitions are shaped by systems‑wide interactions rather than transport‑specific dynamics alone. Results from the global and endogenous modeling framework highlight how system‑integrators (e.g., electricity, biomass, carbon capture technologies, and co-products availability) govern the allocation of resources and the timing of transition across sectors. Sectors with higher mitigation flexibility, often associated with greater electrification potential (e.g., heat and road transport), tend to transition earlier, thereby relaxing systems-wide constraints and allowing hard‑to‑abate sectors, particularly aviation, to transition more gradually. The findings further show that the role of liquid fuels as sustainable aviation fuels is strongly dependent on carbon budgets, biomass availability, and carbon storage capacity, reflecting cross‑sectoral trade‑offs and synergies.

Soft-linking stakeholders engagement with ESOMs enhances the contextual relevance and legitimacy of modeling formulation. By incorporating a socio‑technical dimension, this analytical link strengthens the representation of modeling assumptions, supports scenario development, facilitates mutual learning between modelers and decision‑making stakeholders as well as technical experts. Accordingly, this thesis demonstrates that such a continuous interaction might provide a more robust and realistic understanding of low‑carbon transport systems. Hence this thesis contributes to ESOMs scholarly by moving beyond “one‑size‑fits‑all” approaches into more transparent, context‑sensitive, and decision‑relevant analyses applicable not only to transport systems but to broader energy transitions.