Battery electric bus

A battery electric bus is an electric bus that is driven by an electric motor and obtains energy from on-board batteries. Many trolleybuses use batteries as an auxiliary or emergency power source.

Battery electric buses offer the potential for zero-emissions, in addition to much quieter operation and better acceleration compared to traditional buses. They also eliminate infrastructure needed for a constant grid connection and allow routes to be modified without infrastructure changes, in contrast with a trolleybus. They typically recover braking energy to increase efficiency by a regenerative brake. With energy consumption of about 1.2 kW⋅h/km (4.3 MJ/km; 1.9 kW⋅h/mi), the cost of ownership is lower than diesel buses.

In 2018, the National Renewable Energy Laboratory (NREL) found that total operating costs per mile of an electric bus fleet in the United States in some cases may be less expensive than a diesel bus fleet.

The London Electrobus Company started running the first ever service of battery electric buses between London's Victoria station and Liverpool Street on 15 July 1907. However, the weight and inefficiency of batteries meant that other propulsion technology - such as electric trolleybuses or diesel buses - became commonplace.

The first battery buses were mostly small, mini- or midi- buses. The improvement of battery technology from around 2010 led to the emergence of the mass-produced battery bus, including heavier units such as 12.2-meter (40 ft) standard buses and articulated buses. China was the first country to introduce modern battery electric buses in large scale. In 2009 Shanghai catenary bus lines began switching to battery buses. In September 2010, Chinese automobile company BYD began manufacturing the BYD K9, one of the most popular electric buses

The first city to heavily invest in electric buses was Shenzhen, China. The city began rolling out electric buses made by BYD in 2011, with the objective of having a fully electric fleet. By 2017, Shenzhen's entire fleet of over 16,300 buses was replaced with electric buses, the largest fleet of electric buses of any city in the world.

According to Bloomberg, "China had about 99 percent of the 385,000 electric buses on the roads worldwide in 2017, accounting for 17 percent of the country's entire fleet." Chinese cities are adding 1,900 electric buses per week.

As of 2016 battery buses have less range, higher weight, higher procurement costs. The reduced infrastructure for overhead lines is offset by the costs of the infrastructure to recharge the batteries. In addition, the additional weight of batteries in a battery electric bus means that they have a lower passenger capacity than trolleybuses in jurisdictions where there is a legal limit on axle loads on roads. Battery buses are used almost exclusively in urban areas rather than for long-haul transportation. Urban transit features relatively short intervals between charging opportunities. Sufficient recharging can take place within 4 to 5 minutes (250 to 450 kW [340 to 600 hp]) usually by induction or catenary.