Optimal strategies for zero-emission transport sectors in 100% renewable energy cities

Decarbonising the transport sector is pivotal for achieving climate neutrality, yet integrating zero-emission mobility within renewable energy systems remains challenging due to intermittency, infrastructure constraints, and cost trade-offs. This study employs a holistic approach by integrating a multi-objective optimisation framework with the EnergyPLAN model to examine the interactions between the transport sector and the entire energy system, aiming to identify an optimal long-term decarbonisation pathway. Four transport demand scenarios based on direct and indirect electrification have been assessed, considering the entire value chain and charging infrastructure. The findings reveal substantial variance in renewable electricity mix and total annual cost across the scenarios. Despite lower critical excess electricity production and electricity imports, the “e-methanol scenario” remains the most expensive, driven by the cost of fuel conversion and infrastructure. The levelised cost of charging light-duty vehicles is estimated to range from €0.280 to €0.298 per kWh. In contrast, the levelized costs for alternative fuel refuelling for heavy-duty vehicles are projected at €3.08 per kg for hydrogen, €1.38 per kg for e-methanol, and €0.48 per kg for biomethanol. The study underscores the need for integrated smart energy systems that combine sector coupling and flexibility technologies to balance affordability and flexibility in transport planning.