The transport systems, as large energy consumers and important contributors to greenhouse (GHG), criteria pollutant and noise emissions worldwide, have been permanently challenged by the continuously increased stringent environmental standards to improve its energy efficiency, as well as to reduce its environmental footprint. Transit systems, which operates in urban areas, are particularly subjected to stringent environmental and efficiency regulations, given their proximity to large population concentrations, alongside the urban transport corridors. This is particularly true for bus transit systems, mostly powered by internal combustion engines (ICE), generally fueled with fossil diesel fuel. In this context, transit systems' electrification plays an important role to reach both the energy efficiency and environmental performance targets, currently set by the governments, given the high efficiency of electric drivetrains (compared to ICE), as well as its reduced environmental impact, provided the sustainable pathways for electricity generation. Electric powered transit bus systems are not new - they have been successfully used worldwide, with trolleybus technology, however, with reduced operational flexibility (due to the dependency on the electrical power network) and restricted to highly loaded demand transit corridors, given their inherent high infrastructure costs.
However, the advent of battery technology development, associated with the whole electronics industry, driven mainly by improved battery energy&power densities, reliability and durability, as well as remarkable cost reductions, have opened the way for the electrification of bus transit systems for low to medium loaded corridors, with the use of the so called Battery Electric Bus(BEB) technology, powered with state of the art technology traction batteries. Important cities worldwide, from both Asia, Europe, as well as North and South America, have launched important BEB experiences, focused on the assessment of both electric battery bus and electricity infrastructure technology.
China, currently the leader in battery technology, leads the way, with the higher BEB fleet under commercial service, albeit highly supported on public subsidies for vehicle acquisitions. European and North & South American countries are currently also implementing important BEB pilot programs, which might play an important role in the technology maturation pathway, providing a valuable learning curve for the future massive use of this technology.
This work presents a review of the status of the electric transit bus and traction battery technologies, based on the current available technical literature, as well as a snapshot of current BEB programs worldwide, with a focus on technology maturity, as well as on operational and cost topics.