The first bus converted from diesel to electric drive recently started travelling the streets of Schwäbisch Hall in Baden-Württemberg for the Transdev Group in Germany. The vehicle is the result of a comprehensive retrofit project initiated by the Transdev Group to drive forward the development of even more sustainable public transport without local pollutant emissions. The bus is now in regular service with other e-buses operated by the Transdev subsidiary Stadtbus Schwäbisch Hall and is helping to make the air in the historic centre of Schwäbisch Hall even cleaner.
As part of the conversion, the conventional combustion engine system of the ten-year-old MAN A21 Lion’s City bus was replaced by the innovative electric drive system VEDS (Voith Electric Drive System) from Voith. This is already being used successfully in many electrically powered new vehicles and has received several awards in Europe for its efficiency and sustainability.
The complex conversion is divided into various process steps:
- Reverse engineering
- Creation of the simulation software
- Mechanical design; electrical design
- Installation analysis, detailed design, production drawings
- Production and purchasing
- Mechanical integration
- Testing and technical acceptance
- Technical documentation
In addition to Voith, the partners in this retrofit project are Orten Electric Trucks from Bernkastel-Kues and ToZero electric vehicles GmbH from Rausdorf/Erfurt. Orten Electric Trucks has extensive experience in the field of electromobility since 2012 and specialises in retrofitting conventional commercial vehicles. ToZero, a young company specialising in retrofit solutions for public transport, was responsible for the technical planning and implementation of the conversion.
The topography of Schwäbisch Hall, where the bus is to be used, was a particular challenge in this project. The town stretches along the narrow Kocher Valley with steep slopes leading up to the heights on the edge of the Swabian-Franconian Forest. The energy requirements for regular bus services, some of which have steep roads, are significantly higher here than in flatter regions. To meet these requirements, the ToZero team decided to equip the Lion’s City with additional batteries on the roof. The remaining components, including the standard batteries with the 310 kW (continuous output) VEDS, were installed inside the vehicle to save space. The battery capacity is 420 kWh. The seating remains unchanged and only the additional batteries are visible from the outside.
‘There were several reasons in favour of retrofitting a regular service bus like this,’ explains Michael Dalhof, Managing Director of Stadtbus Schwäbisch Hall GmbH. ‘Firstly, a bus from 2014 still has a few years of use ahead of it. Replacing it with a new vehicle would have been less sustainable and would not have made economic sense – especially as investing in a retrofit is significantly more cost-effective.’
Transdev also cites the fact that a retrofit is significantly cheaper than buying new electric vehicles and is also subsidised by the state as arguments in favour of the conversion. Furthermore, the retrofit reduces the carbon footprint in addition to avoiding local pollutant emissions, as no additional resources are required to build a new vehicle. The age limit for such vehicles in public transport, which is imposed by the transport contracts, has not been clarified – an opening clause is needed here, which would allow refurbished buses to continue to be used for longer.
(Info: Transdev)
