TOSA Buses

Geneva’s breakthrough flash-charging technology for sustainable and emissions-free urban public transport

The TOSA (Trolleybus Optimisation Système Alimentation) bus planned to be running a full bus route in the city of Geneva takes only 15 seconds to charge during stationing time at a bus stop. In the time that it takes for passengers to get on and off the bus, a laser-guided arm sends 600 kW straight into onboard lightweight batteries with a brand-new flashing technology developed by engineers at ABB, a leading global technology company in power and automation. The charge allows for the propulsion until the next bus / next charging station. Since May 2013, the city is successfully running a pilot and plans to operate the full bus line by 2018.

Initiating context

Geneva (Switzerland) is one of the world’s leading cities, recognized as a financial hub, a global center of diplomacy and a technology and innovation center. It is also a popular tourist destination, offering a high quality of life to its residents. It hosts the highest number of international organizations in the world, including global headquarters of institutions like the United Nations and the Red Cross.

The local transport authorities in Geneva have a vision of providing a silent and zero–emission urban mass transport for the city. The commitment is to develop citizen-focused solutions and technologies that help lowering environmental impact. Alternative electric bus technology normally requires buses to be charged overnight at the depot, and carrying such large batteries requires sacrificing the space for actual passengers. The new solution came from ABB and its partners who had concluded a successful pilot operation of their electric bus system TOSA. Instead of using overhead lines, the buses power up in just 15 seconds at specific stops and at the terminus station.

Project description

ABB, a leading global technology company in power and automation, that enables utility, industry, and transport & infrastructure customers to improve their performance while lowering environmental impacts, had been designing a model for future urban transport that would reinforce their vision of sustainable mobility. Their project will deliver and deploy 13 flash-charging stations along an urban transit bus route in Geneva, as well as three terminal and four depot feeding stations. This route will then use the world’s fastest flash-charging connection technology taking less than 1 second to connect the bus to the charging point. The onboard batteries can then be charged in 15 seconds with a 600-kilowatt boost of power at the bus stop. A further 4 to 5 minute charge at the terminus at the end of the line enables a full recharge of the batteries.

The plan to deploy TOSA on Line 23 in Geneva was the result of collaborative efforts of the public and private sector partners who invested in this vision. The decision was undertaken after the successful pilot of the first e-bus on the route from the Geneva Airport to the Palexpo Exhibition Center. The Line 23 bus route will be slightly modified in order to provide a fast connection to a new suburb being built to accommodate 11,000 flats and office space for about 11,000 employees. After it will be fully commissioned in 2018, the high-capacity articulated buses will depart from both terminuses at 10-minute intervals during peak times, and the line will be able to carry more than 10,000 passengers a day, thus replacing the diesel buses.

The innovation of the rechargeable TOSA buses is that they provide large-capacity (up to 133 passengers), 100% electric propulsion without the use of overhead lines and with batteries that are small and light enough to ride on the roof of the bus. At certain stops, a robotic arm on the roof of the bus comes out automatically and connects to the overhead charging station, giving the batteries 15 seconds of recharging time through a technique called “flash” charging. Though 15 seconds is the normal time it takes for passengers to disembark and embark, it’s enough to store up the energy needed to get to the next recharging station at an upcoming stop or the terminus.

The technology developed by ABB, together with partners, not only automatically flash charges an electric bus in 15 to 20 seconds, but also enables to obtain high transportation capacity and energy efficiency. The system for overhead flash high-power charging is inherently safe because the overhead connectors are only energized when they are engaged, and the electromagnetic fields associated with inductive charging concepts are therefore avoided. [8] TOSA comprises of flash-charging stations at selected bus stops (components: an energy transfer receptacle; a grid connection; AC/DC converter and an energy storage unit) and onboard traction equipment (components: an entirely automatic energy transfer system; a battery unit; traction converter with integrated auxiliary converter, and traction motors).

Implementation process

The Swiss city of Geneva has run a pilot with this technology since May 2013, which proved to be a great success so that the city is now going to run a full bus route, Line 23. The Geneva Public Transport operator (TPG) had signed a contract with ABB and the Swiss bus manufacturer HESS to deliver an operational line by spring 2018. [8] As part of a separate assignment by HESS, ABB will supply 12 flexible drivetrain solutions for the buses including integrated traction and auxiliary converters, roof-mounted battery units and energy transfer systems (ETS), as well as permanent magnet traction motors. Both contracts include five-year maintenance and service agreements to ensure operational reliability, efficiency and safety.

Lessons learned

The TOSA model of emissions-free urban mass transport can be given to cities worldwide, not only in Europe, with the objective of improving public transportation towards increased environmental sustainability.

Considering that urban transport planners around the world are looking for ways to avert gridlock and reduce pollution, the electric TOSA bus system is an attractive model for mass urban transportation. Being quiet, entirely emissions free and using long-life, compact batteries, the visual clutter of overhead electric lines that is often a barrier to trolleybus acceptance can be made a thing of the past.

With diesel buses are becoming increasingly less attractive, both environmentally and financially, and operators seeking towards an attractive, modern form of transportation without having to hang wires in the street, flashcharging is well situated to replace both, existing trolleybus routes and urban diesel routes. [8] This innovative project opens the way for the future of mobility, by providing a sustainable and environmentally-friendly mass transport solution for the well-being of urban communities.