The move to electric drivetrains isn't limited to cars, with bigger vehicles like trucks and buses also ditching internal combustion engines in favor of cleaner alternatives. Continuing along this route is Daimler subsidiary EcoBus GmbH, which has signed a memorandum of understanding with public transport operator Rhein-Neckar-Verkehr GmbH for the supply of the first fully electric Mercedes-Benz Citaro city buses towards the end of 2018.

The Citaro is EvoBus's best-selling bus and, as well as the conventional diesel-powered versions, it has been produced for some years with hybrid-electric and fuel cell-electric drivetrains. Adding to the propulsion options, in May 2017 the Citaro E-CELL fully electric version was announced for production launch during late 2018.

With recharging infrastructure still in the development phase and customers' range requirements varying, the Citaro E-CELL can be configured to meet differing requirements using a modular approach that Mercedes-Benz calls the Citaro E-mobility Platform. As expected, a higher range requires larger battery capacity and reduces transport capacity. Conversely, shorter range capacity requires more investment in recharging infrastructure away from the main depot.

The Citaro E-CELL is equipped with lithium-ion batteries in modular packs and drive is via electric wheel hub motors at the rear axle that feature precise thermal management for both the bus's drivetrain and climate control systems to optimize efficiency and reduce energy consumption. Comprehensive testing of prototypes, including during winter within the Arctic Circle and summer in Spain's Sierra Nevada, has already been conducted. Endurance testing and refinement will also continue during 2018.

"We are not interested in prototypes, we're all about series (production)", says Gustav Tuschen, Head of Development at Daimler Buses and member of the board at EvoBus. "Electric drive is no longer a niche, it's a major player. By 2030, 70 percent of all newly-registered urban buses will have emission-free drive systems."

The two parties have also agreed to share information on the day-to-day performance of the buses during normal operations, which should be aided by the fact the EvoBus manufacturing plant is in Mannheim, Germany, and the first customer trials will be conducted in the nearby Rhein-Neckar metropolitan region.

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