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What is an electric bus?

One growls, coughs and belches pollutants into the air as it moves noisily along urban streets; the other whirrs along quietly, emitting nothing into the air and generally leaving passengers (and the people it passes by) feeling peaceful and enjoying the ride: the latter – a zero-emission electric bus – represents the future of urban public and sustainable mobility. Why? Start with the user experience, which is critical to encouraging ever more people to adopt public transport as part of efforts to create more sustainable cities. Aside from the user experience the zero emissions bus offers many additional advantages over its fossil-fuel powered cousins, including:

  • greater performance efficiency;
  • lower operational expenditures - compared to diesel buses, electric buses cost about 50% as much to operate, mainly due to lower costs associated with powering the buses;
  • lower maintenance expenses, equivalent to almost half the cost for diesel buses as electric buses have fewer components;
  • ease of battery recharging, thanks to electric socket charging;
  • regenerative braking, which allows for converting heat generated by braking into electricity to recharge batteries.


Thanks to their ability to cut pollutants and climate-altering greenhouse gas emissions while keeping noise levels to a minimum, electric buses improve living conditions for urban residents. and increase the electrification of transport. Which explains why, unsurprisingly, they are finding increasing use not only in terms of urban public transport, but also as alternatives to petrol-powered school and shuttle buses.

What are the benefits and advantages of electric buses?

City administrations and public transport companies that invest in creating an electric bus fleet gain significant economic, environmental and management advantages.
  • Environmental benefits of electric buses: the exhaust fumes of diesel buses are a health hazard in big cities and are extremely unpleasant to breathe. Electric buses have zero tailpipe emissions. Intelligent transportation systems for smart cities are a key stepping stone to cleaner air, decarbonization and fighting climate change.
  • Community and social benefits: an efficient and sustainable public transport system preserves citizens and safeguards their health, as air pollution can significantly increase the population's mortality risk. Moreover, a sustainable public transport makes a city much more liveable by reducing the noise pollution created by loud and clunky diesel buses. Looking at the big picture, electric buses invite city managers to rethink their infrastructure needs. Electric buses silently glide through urban avenues, maintaining lower noise levels both inside and out, making it a wise transit choice for heavily populated streets and neighborhoods.
 Electric Public Transportation

Electric Public Transport

Zero-emissions mobility for sustainable cities

Passengers enjoy a comfortable ride, thanks to pneumatic suspension technology and the positive experience on board has seemingly translated into greater civil respect for the vehicles. Studies have shown a greater willingness to comply with civic rules and to respect the community from the introduction ol electric buses, with a reduction in fare evasion and graffiti markings.

  • Economic benefits: the initial costs of switching to an electric fleet can be high because of the spending needed to build a charging infrastructure. But this investment is offset by savings of up to 70% in other areas: electric buses have lower consumption costs, fewer components, require less maintenance and have a longer life cycle. They may be more expensive at the beginning, but they are far cheaper in the medium and long term. To help with financing, Enel X offers e-Bus as-a-Service, an integrated turnkey solution in which Enel X covers the initial investment and takes on the operating risk. Moreover, public administrations and public institutions in general indirectly benefit from saving on public health costs.
  • Optimized energy consumption: energy costs can fall even more with new electric bus deposits, which - thanks to smart charging technology - can cut electricity consumption by 40 percent.


The advantages go beyond cleaner cities and lower operating costs. There are also important performance differences between electric bus vs diesel bus. An e-Bus offers better performance both in terms of drivability, maintenance and consumption.
According to a 2021 study carried out by Bocconi University and Enel in several Italian cities, an 8-meter diesel bus cost 0.21 euros per km to maintain, while the same size electric bus cost 0.12 euros per km.
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How does an electric bus work?

Electric buses work just like electric cars do. An electric bus plugs into the electricity grid to get charged, and stores the electricity in batteries (often located on the roof). The batteries power an electric engine. Since an electric engine has fewer parts than an internal combustion engine, it requires less maintenance. When the batteries are depleted, the bus is recharged at charging stations (which takes an average of 4 hours with a 150 kW charger). Since buses run on regular routes, scheduling a timetable for batteries to be recharged is a fairly straightforward planning exercise. Depending on the size of the bus and on such factors as traffic and road surface conditions, driving styles, average weather temperatures, load factor (and more), a bus can travel an average of 250 km (155 miles) on a single charge during its first year in service.
Smart City

City Solutions

An ecosystem of electrified and digitalized urban infrastructure combined with innovative solutions

How do electric buses charge?

There is no magic to charging an electric bus. Indeed, electric bus charging works the same way it does with cars and other consumer technology, like phones: plug it into a power outlet and it charges. Electric buses for public transport have dedicated electric bus charging stations – often at depots – where they can access a range of chargers (for depot or overnight charging); in other cases, buses are recharged at high power at the terminals or at some stops along the route (opportunity charging). For example, a typical 150 KWh charger can completely recharge an electric bus battery in about four hours. Given that their batteries are large, buses can take longer to recharge fully than cars, so their schedules are most often designed to allow them to recharge at bus depots overnight. Buses that have heavier route loads – either longer routes or greater route frequency – can make use of fast charging systems located at depots and transit centers – that allow them to be fully recharged in as little as a couple of hours.


Other recharging solutions exist:

Second life batteries

Second life batteries

Batteries can have a second chance to create sustainable value, enabling a more efficient energy consumption

  • Pantographs - some electric buses come equipped with pantographs, giant arms that stretch skyward and connect to overhead power lines. Buses equipped with pantographs can charge on the go, by connecting their pantographs to the overhead power lines that track the bus’s route;
  • Wireless recharging - buses that recharge wirelessly are equipped with inductive charging technology – much like that available in consumer products like (again) mobile phones, power tools, medical devices and even electric toothbrushes. Instead of plugging the bus into a socket, the bus parks on a special pad that uses magnetic fields to create electric current which can then charge the bus without there being a direct connection between charger and bus.
In all cases, it is crucial that electric buses have access to regularly available and reliable power supplies. Also, proper route planning and infrastructure positioning help to make sure that electric buses never run out of power when they’re on the job.

What distance can an electric bus travel on a single charge?

Electric buses do not require a huge driving range, for programming their recharging schedules and making sure they have the requisite energy to cover their routes is fairly simple. That said, many factors determine the range a fully-charged electric bus can attain, including:
  • weather - warmer temperatures allow for longer ranges, in part because heating in winter requires more energy;
  • load factor - the more people an e-bus carries, the heavier it is, the more energy it uses to cover its programmed routes;
  • battery size - the equivalent to a petrol-powered car’s fuel tank; in this case the bigger the ‘tank’, the longer the range;
  • route topography - flatter vs. hillier routes (which may be less critical if a bus has regenerative braking capacity);
  • road conditions in general;
  • bus driver’s driving style: a ‘lighter foot’ translates into longer distances between charges.
So, what is the range a fully charged electric bus can cover? On average, current electric buses for urban mobility use have a range of between 200 and 300 km. Other types of electric buses may be equipped with larger battery packs, enabling them to reach longer driving ranges between charges. Naturally as battery technology improves over the years, the driving range of electric buses – like that of other forms of electric transport – will increase, making them even more efficient.

How to optimize the charging of electric buses?

The electrification of public transport through electric buses requires a wide range of capabilities and installing a new infrastructure of EV fleet charging stations. 
Charging an e-Bus varies depending on the type of charger and the vehicle’s capability to absorb a charge. With a 150 kW charger, for example, it takes an average of 4 hours to charge a 450 kW battery. A fleet of electrical buses is charged respecting the available power at the electric charging station. Furthermore, if one bus requires less power, the remaining power is allocated to other electric buses. Thanks to charging management software and smart charging algorithms like the ones developed by Enel X, a public transport company can schedule charging sessions based on the real charging need of its fleet, in order to charge each vehicle to the desired level and at the right time. For this purpose, the integration of vehicles' scheduled blocks - carried out manually or automated (e.g. with the scheduling suite integration) - will assist the planning of charging sessions, making it more efficient. 

Moreover, smart charging services allow to:

  • balance load across multiple charging stations without exceeding a specific power limit (Load Optimization);
  • identify and set different priority logics to charge buses (Charge Prioritization). For instance, priorites can be defined based on the order of arrival (First In First Out logic, the first electric bus to arrive is the one that charges first), on scheduled departure time or on station's or vehicle's availability;
  • to schedule charging sessions considering both vehicles' charging needs and the electricity rates (Tariff Optimization).


What happens to these enormous batteries when they reach the end of their useful life cycle after 7-8 years? When batteries reach the end of their useful life, they can be reused, becoming a so-called “second life” battery. This can happen in two ways. Repurposing, wherein several suitable packs are selected and combined based on factors including residual state and capacity. Refurbishment of packs is a second viable option. In this case, packs are disassembled and then single cells are reconditioned and repacked into new modules.

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