E-power from Swabia

Germany and its manufacturers are determined to keep pace with these developments. The eCitaro is now rolling off the Mercedes-Benz production line. We have already had an opportunity to ride in it, and among its impressive features is the combination of the tried and tested ZF AVE 130 electro-portal axle with two 125 kW three-phase, synchronous motors mounted near the wheel hubs and producing a torque of 485 Nm each. Not only does this produce good acceleration and regeneration but is also comparatively quiet. The electric bus is programmed to restrict the number of transducer processes to a minimum in order to conserve energy. Pressing down on the brake pedal initially causes deceleration electrically, and then with compressed air, and in each case the maximum possible energy is regenerated.

The Swabia-based bus manufacturer is also increasingly getting to grips with the problems of range. An entirely new development is the maximum installation of 12 battery packs with a capacity of 292 kWh, of which some 80 percent is usable, i.e. roughly 234 kWh. For most of the invitations to tender and bids Mercedes-Benz now uses this maximum arrangement. By the end of 2019 the battery supplier Akasol will also have the new 50 Ah cell technology available, replacing the existing 37 Ah cells. With more or less the same weight and installation space, each battery module will then have a capacity 33 kWh, compared with the current 24.5 kWh, making a total capacity of 396 kWh possible with 12 modules. At the same time the energy density increases to 183 Wh/kg. And what is more: by the middle of the year the Hesse-based battery specialist will also be able to incorporate Type 2170 round cells in its batteries. The high-energy modules with a capacity of 40 kWh have a high energy density of 221 Wh/kg. This will enable more than 500 kWh to be integrated in a 12-metre bus, giving a winter range of some 250 kilometres, which is sufficient for 70 percent of all daily bus journeys in Germany.

Furthermore, by 2020 batteries with cobalt-free LMP technology from Blue Solutions (Bolloré) will be available. Although, compared with the existing NMC batteries, these solid-state batteries are not capable of taking a fast charge, they do have a higher energy density and output and are safer to use. With the increase in battery capacity, however, the cost of the eCitaro has also risen. Whereas the well-equipped diesel version costs around 280,000 Euro, the price of an e-bus with the 243 kWh battery package is at least 600,000 euros, although a minimum of about 256,000 euros can be met through subsidies.

Germany’s other hopes

By the end of 2020 MAN will be introducing its electric Lion’s City with a maximum of six battery packs and 470 kWh. Even though, to protect the cells, only 300 kWh will be used, a daily range of up to 200 kilometres is still possible, because the Munich-based company is deploying a fossil-fueled supplementary heater from Valeo. The corresponding articulated bus will have 630 kWh batteries on board, of which around 400 kWh will be usable.

In terms of battery size other manufacturers now have a great deal to offer too. For example, for its models, from the midi to double-articulated e-bus, the specialist company Sileo from Salzgitter can supply batteries of up to 550 kWh. For its current range the German-Turkish company has boosted the energy density of its storage system, without any weight increases, from 85 to 134 Wh/kg compared with its predecessor, thereby substantially extending the range.

Europe’s first e-bus factory

Irizar also intends to make serious inroads into the German public transport market. The Basque company has chosen Ferrostaal as its partner in Germany, and the latter is well acquainted with this market, in particular after several years in association with MAN. A new factory has just been set up in Aduna, northern Spain, exclusively for e-bus production, and it breaks new ground in Europe in terms of its size and its manufacturing focus.

Moreover, with the ie bus and ie tram they already feature an attractive products in their range. The 12-metre type ie bus that we tested has roof-mounted batteries with a capacity of 375 kWh, of which 337 kWh is usable. They weigh no less than 3.2 tonnes including peripherals, giving an energy density of 115.4 Wh/kg. We calculate that this gives the vehicle a minimum range of 170 to kilometres, and as much as 230 kilometres under ideal conditions. This can, however, be extended with the optional 450 kWh battery package, which should enable daily distances of between 200 and 270 kilometres to be covered. And all this is available at quite a moderate price: depending on the configuration Irizar will be selling the ie bus in its 12-metre version for between 500,000 and 550,000 euros. And of this total some 250,000 euros is accounted for by the 375 kWh battery.

Everywhere that one looks: a new start

In the bus sector one of the pioneers in electrification is the French company Heuliez, an affiliate of Iveco. Its wide-ranging approach includes not only the electric city bus version of the GX with lengths of 12 and 18 metres, but also services intended to facilitate the use of electrical drive systems: a simulated electro-mobility system for finding solutions to meet the needs of different transport companies, battery hire arrangements, a selection of modular and scalable types of batteries, chargers from leading European suppliers, data management over the air und preventive maintenance.

Other manufacturers have also entered the electric market, in particular Alexander Dennis Limited (ADL) with its Chinese partner and specialist in electromobility BYD, and the Sino-Dutch manufacturer Ebusco. We can therefore rest assured about the future electrification of public transport in Europe.