Electromobility

eCitaro_Flotte

The eCitaro - ready for the city of tomorrow

The desire for better air quality, quality of life and sustainable mobility in the city is increasing. One solution is climate-neutral local public transport (LPT). Daimler buses offer custom overall concepts for this very objective: the battery-electric Mercedes-Benz eCitaro is the centre of a complete eMobility system.

In Wiesbaden, a city without a tram or underground, buses are omnipresent. Perhaps this explains the vehemence with which ESWE Verkehrsgesellschaft is pursuing the conversion to electromobility. Mercedes-Benz eCitaros have been in everyday service in Wiesbaden since the first deliveries in December 2019, with a total of 120 estimated to be in use by the end of 2021. In the future, the entire fleet of nearly 300 buses will be fully electric or powered by hydrogen, and thus locally emission-free: a key element for better quality of life in the Hessian state capital.

Premiere of the eCitaro in everyday city-life: At the end of 2019 Wiesbaden put the first electro buses into operation.
Premiere of the eCitaro in everyday city-life: At the end of 2019 Wiesbaden put the first electro buses into operation.

The Mercedes-Benz electric bus hums quietly through the city

In the hustle and bustle of the city, the “fresh air role models”, as the people of Wiesbaden call their battery-powered buses, stand out only to the trained eye. In the case of the e-bus, Daimler has consciously opted for the Citaro, which has proven itself thousands of times over. Passengers may notice the new, futuristically designed front with the Mercedes-Benz ornament. Once you’ve boarded, however, the interior is immediately familiar.

Line 1 runs north from the historic main station up to the Neroberg, a green oasis above the city. Pleasantly quiet, the battery-powered bus picks up speed and whirs softly through the classical architecture of the town houses.

It’s a relaxed ride on the e-bus; passengers aren’t aware of the enormous challenge associated with the sustainable transport transformation. Rüdiger Kappel of Daimler Buses, on the other hand, is all too familiar with the hurdles in developing the urban transport of the future. For him, Wiesbaden is a prime example of how such a switch can function smoothly. “Our strategy is working. The eMobility system, with the fully electric Mercedes-Benz city bus at its centre, is helping the transition to electromobility.” Kappel heads fleet sales for buses by Mercedes-Benz and Setra in Germany.

Rüdiger Kappel.
Rüdiger Kappel.

Momentum for zero-emission drives in urban bus transport

In his position, with a high proportion of city bus customers, the conversion to alternative drives is a major issue. “If a transport company wants to get into e-mobility with a few vehicles, that’s easy with learning-by-doing. But that won’t give us the momentum we need for zero-emission drives in urban bus transport,” says Kappel. “When we talk about large-scale change in a relatively short period of time, it requires a highly intensive consulting process and initial planning.” After Wiesbaden with its complete perspective changeover, Duisburg is the second system customer to benefit from the expertise and wealth of experience, as well as the conceptual solution approach, developed by Daimler Buses.

Conversion to electromobility in LPT needs support

The transport transformation is quite the feat – not least in financial terms. For example, a fully electric Mercedes-Benz eCitaro costs two to two-and-a-half times as much as a conventionally powered Citaro. The state can help absorb these kinds of additional costs. At the moment, up to 80 percent of the additional outlay is subsidised. Rüdiger Kappel: “The rapidity of the transition to electromobility creates high financing peaks. Only with a subsidy for the electric portion is this investment at all financeable for transport companies.”

The Mercedes-Benz eCitaro G articulated bus. With a passengers count of up to 146 persons it is the perfect solution for heavy traffic routes.
The Mercedes-Benz eCitaro G articulated bus. With a passengers count of up to 146 persons it is the perfect solution for heavy traffic routes.
New, but still familiar: The eCitaro is based on the construction of its conventionell counterpart, the Citaro.
New, but still familiar: The eCitaro is based on the construction of its conventionell counterpart, the Citaro.
The eCitaro at the standart charging station. Intermediate charging via pantograph on the route or via loading rails is also optionally possible.
The eCitaro at the standart charging station. Intermediate charging via pantograph on the route or via loading rails is also optionally possible.
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Lithium-ion batteries and innovative solid-state batteries

While details of tried-and-tested diesel technology are still being optimised at best, electromobility is experiencing further advancements in short cycles. Battery technology in particular is making real leaps forward in innovation. “We started with the normal lithium-ion batteries. Then we were the first series manufacturer to offer an innovative solid-state battery. And today’s batteries already have the next generation of the first technology, increasing range even further with the same volume,” says Kappel, describing what has happened in the past two years alone.

The two battery types serve different requirements. With up to 396 kWh in total lithium-ion battery capacity, the eCitaro currently achieves a practical range of around 200 kilometres without recharging. With 441 kWh maximum capacity, the lithium-polymer batteries are capable of at least 230 kilometres in extreme operation, such as in the winter or typical city bus use. Under favourable conditions, it can be up to 100 kilometres more. These solid-state batteries are more durable and have a higher energy density, but only tolerate a lower power output during fast charging. And development isn’t stopping: “In the future, we want to use hydrogen-powered fuel cells as range extenders. Then the electric bus will also be usable across long distances and over land,” says Kappel, looking a few years ahead.

 Battery assembly on the eCitaro in the Mannheim plant. Either two, four or six battery modules are used on the roof of a solo bus. They are supplemented by four additional modules in the rear as standard.
Battery assembly on the eCitaro in the Mannheim plant. Either two, four or six battery modules are used on the roof of a solo bus. They are supplemented by four additional modules in the rear as standard.
 Fully electrically powered city buses put more weight on the road because of their batteries. The eCitaro masters the challenge thanks to the variable position of the battery modules and a front axle with a permissible axle load of eight tons.
Fully electrically powered city buses put more weight on the road because of their batteries. The eCitaro masters the challenge thanks to the variable position of the battery modules and a front axle with a permissible axle load of eight tons.
The slewing ring of the eCitaro G. It is used as platform for the central joint.
The slewing ring of the eCitaro G. It is used as platform for the central joint.
Manufacture of the roof equipment rack. Production at the Mannheim plant takes place on the same lines as the conventionally powered Citaro.
Manufacture of the roof equipment rack. Production at the Mannheim plant takes place on the same lines as the conventionally powered Citaro.
The eCitaro. Ready for the city of tomorrow.
The eCitaro. Ready for the city of tomorrow.
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Consulting and planning reduce complexity

The goal of Daimler Buses is to reduce the complexity of electromobility for customers. Although the vehicle plays a central role, ultimately it’s just one part of the overall system. That’s why Daimler Buses has developed a holistic advisory concept around the eCitaro with six additional elements:

• Operational plan: This could include optimal coordination of depot processes, routing, round trips, midway charging or timetables, with the strengths of the eCitaro.

• Charging infrastructure: Here, the experts at EvoBus design and recommend customised solutions for vehicle charging. The standard solution is to use the usual plug-in charging method at charging points in the depot. Alternatively, charging can also be done on the road with current collectors on the roof or charging rails.

• Power supply: Mercedes-Benz eMobility Consulting provides support in planning the infrastructure, calculates the power supply, recommends the appropriate charging technology and offers solutions from a single source with cooperation partners.

• IT system & communication: The networking of the eCitaro with the charging infrastructure and the provision of vehicle-specific data for management systems via OmniPlus ON provide operational reliability and create potential for efficient operation.

• Battery technology: The lithium-ion and solid-state batteries allow for high range and an update in the vehicle life cycle. The consultation will determine which battery type is optimal for the planned customer application.

• Service & after sales: This includes training drivers and bus depot service personnel, as well as the complete depot management system as an option.

“In Wiesbaden, we had a lead time of about a year and a half for all the project planning and system design,” explains Karsten Wasiluk. The expert came to Daimler Buses Innovation Lab Mobility Solutions from an automotive-specialised strategy consultancy, and was involved in the eCitaro project from the very beginning when the consultancy was established. “It’s important to lay a foundation for successful operation of the e-buses later with realistic feasibility studies and sound advice and planning.” With an intelligent, modular battery and charging technology concept, transport companies can tailor the eCitaro precisely to their individual needs in a future-proof manner. To this end, however, operating processes need to be adapted and an efficient infrastructure created. “You don’t just rebuild a depot that way. These are decisions for decades,” says Wasiluk, referring to charging and depot management, showing why the expertise and experience of Daimler Buses’ consultants are so important.

Karsten Wasiluk.
Karsten Wasiluk.

Take Wiesbaden, for example, where 56 charging stations were installed with a connection to the medium-voltage power grid. “Properly planned, this depot charging infrastructure can even relieve the power grid.” The consultants are responsible for organisation and technology. For them, the people factor is just as important. “To create optimal reach, the bus drivers need to have the right passion for electromobility. Their motivation is crucial.” And the consultants’ focus is constantly expanding. In the meantime, consultant Karsten Wasiluk is also overseeing the second-life strategy for the batteries. When they’ve reached the end of their useful life in the eCitaro, they lead a meaningful second life in stationary electricity storage systems, for example, as a contribution to sustainability.

eCitaro: From Mannheim to multiple European cities

In many European cities, the eCitaro and the eCitaro G as an electric articulated bus are now rolling as emission-free local transport. The solo bus with up to 37 seats and the eCitaro G articulated bus with up to 46 seats for lines with very high passenger volumes are produced at the Daimler Buses plant in Mannheim – integrated in the normal modular production line. As a result, Daimler was able to gain a wealth of experience from the tried-and-tested model, utilize employees’ expertise, and produce at the usual high quality right from the start, as Philipp Heyne, project manager for the production of the eCitaro at Daimler Buses, explains.

Philipp Heyne (left) and Felix Würthwein, project manager for high-voltage systems and components.
Philipp Heyne (left) and Felix Würthwein, project manager for high-voltage systems and components.

In addition to integrating the complex battery and charging technology, the developers also had to tackle some special challenges. The range of electric vehicles is essentially dictated by energy consumption, which poses a particular challenge for buses in public transport. Heyne: “They’re used differently than passenger cars. A large part of the energy consumption goes into air conditioning the significantly larger passenger compartment. It also needs to work well in sub-zero temperatures and when the doors are opened frequently.” With an electric bus, heating through waste heat from the engine is not really possible, as it is hardly ever produced. The solution is an innovative “thermal management”. Compared to the current combustion engine Citaro, the energy requirements for heating, ventilation and air conditioning are reduced by around 40 percent. This exceptional energy efficiency is the foundation for a practical range, even under unfavourable conditions. Another plus: pre-heating in winter or pre-cooling in summer is already performed using the mains at the depot, and is focused on passengers’ comfort.

Because electric vehicles lack the usual background noise, ancillary noises had to be minimised, for example by mounting the ancillary units differently. “Otherwise, the eCitaro offers the familiar, excellent driving experience, which is more like gliding, like a tram,” assures Heyne. As with the “normal” Citaro, all potential special customer requests can be realised over and above the standard equipment, from curtains to USB sockets on the seats.

Positive environment record and a “Blue Angel”

The eCitaro is going to make urban public transport mobility more sustainable – especially when networked with alternative mobility services, such as car shares or ridesharing. Rüdiger Kappel is proud: “Our all-electric city bus was the first to be awarded the ‘Blue Angel’ eco-label. Even if you include the battery production, it’s still a positive environmental record.” Even with the usual German electricity mix, carbon emissions are lower than those of the diesel-engine Citaro. With electricity from renewable energy sources, the balance improves significantly once again.

If the framework conditions remain positive through subsidies, the sales manager expects a strong growth of e-mobility in local public transport – from around ten percent now to 70-percent CO2-free drives in 2030. And although new market players from places like Asia are appearing with electric technology, Daimler Buses is sticking to its claim of market leadership. “We want to secure our share of over 50 percent of the German market,” says Kappel, confident that the eCitaro and the overall concept will continue to convince customers in the future.

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Holger Mohn

is especially pleased that Wiesbaden is making such great progress in terms of sustainable local public transport. Not only because the city is primarily relying on the eCitaro to do so, but also because he has been reminded once again that somehow, he has never visited the capital of his home state, Hesse.

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