This study addresses the environmental problems stemming from greenhouse gas (GHG) emissions from public transportation in the cities of Chillán and Chillán Viejo. Specifically, it analyzes emissions from fossil-fuel-powered buses, which contribute to climate change and negatively affect people’s quality of life. Given this situation, the need to reduce these emissions and move towards more sustainable mobility systems is recognized. The main objective of this research is to estimate the CO₂-equivalent reduction that could be achieved by replacing fossil-fuel-powered public transportation with electric vehicles in the aforementioned cities. To this end, the ISO 14064 methodology is used, subject to specific scope and limitations. This study reviews key aspects, including current environmental legislation, Chile’s international commitments regarding climate change, and the state of emissions in the transportation sector, to illustrate the current state of electromobility in Chile. Finally, the impact of the transition to electromobility in public passenger transport by bus is quantified, resulting in a reduction of 9429 tons of CO₂ equivalent emissions, equivalent to 63.4% compared to the 2023 bus fleet, considering the average emission factor of the national electricity system for 2023. The proposal consists of implementing a 100% electric bus public transport system, highlighting its advantages in reducing emissions, improving energy efficiency, improving air quality, and reducing noise pollution. However, this requires a significant financial investment of approximately USD 57 million, excluding public charging stations for electric buses. Furthermore, public policies offering means of accelerating the transition of public transport in Chile are analyzed.

This paper presents an initial estimate of the energy demand and charging power requirements for the initial replacement of internal combustion public transport buses by battery electric buses in Chillán and Chillán Viejo, Ñuble Region, Chile. The analysis is based on an operational baseline derived from route lengths, service frequencies, departures, and fleet data, combined with official energy and transport demand projections. A case study is conducted for the introduction of 10 battery electric buses on Line 13 of public transport, comparing 100% overnight depot charging and 80% overnight charging complemented by opportunity charging. Results show that the initial 10-bus deployment would require an installed depot charging power between 300 and 450 kW, depending on the charging strategy, with an annual delivered energy of 1149.75 MWh. Long-term scaling scenarios suggest that bus-dedicated charging infrastructure could require between 4.52 MW and 22.35 MW by 2050. Although the numerical results are specific to the case study, the main contribution of this study lies in an operationally grounded planning framework that links the sizing of pilot routes with long-term charging demand scenarios and charging infrastructure projections, providing a transferable basis for preliminary electric bus planning in other mid-size or emerging regions facing similar infrastructure constraints.