It emits zero local emissions and runs almost silently. It combines the thousand fold proven platform of Mercedes-Benz’ best-selling city bus with new technological solutions and an independent design. The all-electric Mercedes‑Benz eCitaro takes electric city buses to a new level and impresses with its innovative thermal management system with exceptional energy efficiency and reliability of range. Its performance enables the eCitaro to cover a large part of the requirements of the transport operators right from the start.
“We no longer place a question mark after electric mobility for trucks and buses – we rather place an unequivocal exclamation mark! With our world premiere of the eCitaro, we are shaping the future of the public transport network – and that is of great significance to our customers, to society and naturally enough to us at Daimler Trucks & Buses as well. That is why we are consistently working on the electrification of our vehicles – and we have been doing so for many years now”, explains Martin Daum, Member of the Board of Management of Daimler AG responsible for Daimler Trucks & Buses.
It will be easy to spot the Mercedes-Benz eCitaro in the city in the future: It is based on the familiar looks of the Citaro, but takes up elements from the design idiom of the revolutionary Mercedes‑Benz Future Bus concept vehicle, thus transporting the unmistakable design of the Citaro into the future. This is particularly evident in the face of the eCitaro. Overall, the eCitaro sports a solid appearance with clearly drawn contours. Optical tricks lend the eCitaro perfect proportions and make it seem light.
The first Mercedes-Benz eCitaro will be delivered at the end of the year and will go into practical operations in the context of a so-called customer-oriented driving test. The Rhein-Neckar-Verkehr GmbH, operator of the local public transport system in the Rhine-Neckar metropolitan region, signed a corresponding declaration of intent with the Daimler subsidiary EvoBus GmbH. Series production of the Mercedes-Benz Citaro with all-electric drive will then begin at the end of the year at the Mannheim bus plant. The transport operators in Hamburg and Berlin have already ordered a total of 35 eCitaro buses.
In order to shape the future of mobility, Daimler Buses is investing around 200 million euro in the implementation of the CASE strategy, and that is just up until 2020. CASE at Daimler stands for the future topics of connectivity (Connected), autonomous driving (Autonomous), flexible use (Shared & Services) and electric powertrains (Electric). A significant proportion is going toward building up competencies, and into development and production of electric buses. Series production of the Mercedes-Benz eCitaro will take place in the Mannheim production plant. The development team based in Neu-Ulm will also be increasingly dedicating themselves to semi-automated and automated driving in future.
An overview of the Mercedes-Benz eCitaro
The platform of the new Mercedes‑Benz eCitaro is the Citaro, the brand’s best-selling city bus with more than 50,000 units sold. Lithium-ion batteries with a total capacity of up to about 243 kWh provide the power for the eCitaro.They are modular in design: the batteries are divided between as many as ten modules, each supplying around 25 kWh. In addition to two battery modules on the vehicle roof, the standard equipment includes four battery modules in the rear of the bus. Depending upon customer requirements, another two or four battery modules are mounted on the roof of the eCitaro. With a minimum of six and up to a maximum of ten possible battery modules, transport operators can adapt their usage and charging strategy very precisely to individual needs.
With the maximum complement of ten battery modules, the eCitaro in standard specification weighs around 13.44 tonnes. In conjunction with a gross vehicle weight rating of 19.5 tonnes, this corresponds to a payload of more than six tonnes or around 88 passengers – in line with what is needed in practice even during rush hour.
The eCitaro’s charging technology also allows it to adjust to the individual wishes and requirements of the transport operators. For the start of series production, plug-in charging is intended. To this end, the city bus has a connection for a Combo 2 plug. If opportunity charging is required to extend the range, there will also be an option to charge the eCitaro via a pantograph in future.
However, the battery capacity alone provides little indication of the actual performance capability and, above all, the range of an all-electric city bus – the true measure is that of energy consumption. In the case of a city bus, this is impacted significantly by climatic conditions and consequently by the need to cool and, above all, to heat the interior. The engineers have therefore put a considerable amount of thought into the issue of thermal management. It is one of the outstanding features of the eCitaro and has been honed and refined in every detail: compared with the current Citaro with combustion engine, the energy requirement for heating, ventilation and climate control has fallen by about 40 percent. This exceptional energy efficiency provides the basis for the eCitaro’s practical operating range – even under unfavourable conditions.
Operating range figures for all-electric-powered city buses are often difficult to compare since reference values can be missing and the figures have often been calculated under ideal conditions. Things are different with the eCitaro: In the interests of reliable data, Mercedes-Benz prefers to consider a “worst-case scenario” and therefore takes its direction from the challenging standardised city driving cycle known as SORT2. To make things even trickier, Mercedes‑Benz also adds the energy requirements of the ancillary consumers into the equation. According to SORT2, the Citaro with a full complement of batteries should be able to achieve an operating range of around 150 kilometres (93 miles) in the summer. In other words, it is already possible to serve some sub-networks within the daily workload of a city bus without opportunity charging. Without opportunity charging, the eCitaro already covers about one third of all requirements of the transport operators. Under ideal conditions, the eCitaro even drives around 250 kilometres (155 miles) without opportunity charging.
The future is electric: kick-off for an innovation initiative
The new Mercedes-Benz eCitaro of the year 2018 is the kick-off for an innovation initiative with a clear strategy aimed at the swift and above all practical electrification of public transit with buses in cities and population centres. The eCitaro will be able to replace city buses powered by a combustion engine nearly completely in just a few years.
Without opportunity charging, the new eCitaro of the year 2018 already covers about 30 percent of all requirements of the transport operators. Since the development of battery technology is progressing at a rapid pace, the eCitaro is already designed to be transitioned to the future battery technology. The next generation of the eCitaro will then cover around 50 percent of all applications. This greater battery capacity also makes a meaningful introduction of an eCitaro G articulated bus with a reasonable range possible. Additional development steps are already mapped out, including the use of so-called solid-state batteries, which are characterised by a particularly long service life as well as high energy density. With a rated battery capacity of about 400 kWh in the solo bus and even more in the articulated bus, the eCitaro will then meet about 70 percent of all requirements without opportunity charging.
Revolutionary step: Fuel cell as a range extender
Subsequently, the range of the eCitaro will be increased yet again by a range extender in the form of a fuel cell that generates electricity. It will be designed to allow the eCitaro to fulfil nearly 100 percent of all requirements on city buses. This technology eliminates the need for opportunity charging and the complex infrastructure required for it in almost all cases – the eCitaro will be able to replace city buses with combustion engine virtually one to one.