Renewable and Sustainable Energy Reviews 141 (2021) 110768 Available online 31 January 2021 1364-0321/© 2021 Elsevier Ltd. All rights reserved. Public transportation with electric traction: Experiences and challenges in an Andean city L.G. Gonz´ alez a , Daniel Cordero-Moreno b , J.L. Espinoza a, * a Department of Electrical, Electronics and Telecommunications Engineering (DEET), Universidad de Cuenca, Cuenca, 010107, Ecuador b Universidad del Azuay, Av. 24 de Mayo 7-77, Cuenca, Ecuador A R T I C L E INFO Keywords: Battery-electric bus Public transport Energy demand Andean cities Renewable energy ABSTRACT The paper studies the energy behavior of a battery-electric bus (BEB) operating on commercial routes as well as the technical feasibility of a total replacement of the current public transport fleet by BEBs in an Andean city. The electrical variables in the BEB charging process are evaluated obtaining THD current distortions of less than 4%, values that meet national and international standards. Regarding the energy demand, the study uses an estimate that allows quantifying the energy consumption of the fleet of 424 BEBsthat would operate the 28 routes. It is estimated that the maximum demand during the charging process can reach 33.92 MW if the fleet is charged at a rate of 80 kW per BEB and 19.96 MW if the charge is at 40 kW, whereas the charging time can range from 4 h to 9 h, respectively. The daily energy needed to power the fleet is 115 MWh, which represents about 4% of energy demanded per day by the city. The estimation of the energy efficiency of the BEB under analysis presents values that vary between 0.67 and 0.94 km/kWh, an indicator that depends on the conditions of the route. The article includes and study on the preference of BEB users as compared to conventional buses. Finally, the study shows a feasible alternative to integrate renewable energy sources for BEB charging, based on photovoltaic solar gen- eration and the use of energy storage systems, as a contribution to the sustainability of the public transport. 1. Introduction Primary energy for electricity generation and transportation repre- sents currently around 60% of the total consumed in the world [1]. If it is consider the high dependence of our development model on the use of fossil fuels, whose emissions have a negative impact on the climate and ecosystems, renewable energy sources (RE) for electricity generation and transport electrification present a great potential for a transition to a new energy paradigm [1]. There are multiple interna- tional efforts, such as the Kyoto protocol or the most recent Paris agreement, that look for reducing greenhouse gas emissions, particu- larly CO 2 , through the development of new technologies that contribute to a cleaner and more efficient electricity generation matrix as well as to a sustainable mobility. Electric vehicles (EV) are a clear example to promote the change towards the use of more efficient and environ- mentally friendly means of transportation. Additionally, among the most important challenges to advance towards sustainable mobility are: increasing the quality of public transport, improving urban planning, promoting shared transport, or the massive use of bicycles, thus chal- lenging the exponential growth of private cars that occurs in many cities around the world [2,3]. If EV can be powered by electricity from renewable sources, then the positive impact would be twofold and we would be moving towards a more sustainable energy model. In terms of public policy for the promotion of RE and EV, recently in the Republic of Ecuador there have been a series of events that arouse the research interest in different areas. For example, the Ecuadorian Constitution, in its article 413, establishes that the State must promote energy efficiency, the development and use of environmentally clean and healthy practices and technologies, as well as renewable, diversi- fied, low-impact energies that do not jeopardize food sovereignty, the ecological balance of ecosystems or the right to water [4]. In October 2018, the country’s Electricity Regulation and Control Agency (ARCO- NEL) approved regulation ARCONEL-003/18 where solar photovoltaic-based generation for self-consumption of final users is allowed, opening the possibility that this small-scale energy can be connected to the national interconnected system - SNI [5]. In March 2019, the Energy Efficiency Law was ratified by the National Assembly [6], where article 14, on energy efficiency in transport, indicates that from the year 2025 all vehicles that join the urban and inter-parish public transport service must only be electric traction-based. Added to * Corresponding author. E-mail address: juan.espinoza@ucuenca.edu.ec (J.L. Espinoza). Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: http://www.elsevier.com/locate/rser https://doi.org/10.1016/j.rser.2021.110768 Received 28 August 2020; Received in revised form 2 January 2021; Accepted 25 January 2021