Integrated analysis of the energy efficiency and carbon footprint of a mixed fleet in urban public transport of a medium-sized city

Abstract

This study presents an integrated comparative and optimisation analysis of the energy efficiency and carbon footprint of a mixed fleet in the urban public transport of a medium-sized city, with a focus on “Municipal Transport Ruse”. The study assesses the impact of the gradual electrification of the fleet by comparing diesel buses, electric buses, and trolleybuses using indicators of energy consumption (kWh/km, kWh/passenger), carbon emissions (kgCO2/km, kgCO2/passenger), and operating costs (€/km). Through scenario modelling and aggregated system indicators, four fleet configurations were analysed, in which the share of electric buses increased at the expense of diesel buses, while trolleybuses remained constant. According the results electric buses are the most efficient, both in terms of energy consumption (0.96 kWh/km) and carbon footprint (0.28 kgCO2/km), while providing the lowest operating costs (0.17 €/km). Scenario analysis with a combined normalised metric confirms significant improvements in the increase in electric buses, optimising energy, emissions and costs. The study highlights the importance of an integrated approach to sustainable urban transport planning and provides quantitative tools for effective electrification and management of mixed fleets.