EPFL

Electric buses are coveted for quietly keeping emissions out of the air. Many of these big vehicles hook into an overhead power line to keep them running. Those lines are unsightly and can require a lot of infrastructure work to install. You could get rid of overhead power lies by running buses solely on batteries, but it's a challenge keeping those batteries charged for long days of operation.

In Geneva, Switzerland, the TOSA (Trolleybus Optimisation Système Alimentation) pilot project is testing electric buses with an unusual method for keeping charged up. The articulated bus has a battery pack on top of the vehicle. When it pulls into certain stations, it connects through a robotic arm to what is essentially an electric bus dock. A 15-second rapid flash charge helps to keep the buses running all day.

Each bus can hold 133 passengers. The fast charge is enough to get the bus to the next charging station, usually located at every few stops. The goal of the TOSA project is to determine the most efficient and cost-effective way to implement electric buses in mass transportation systems. It was built by ABB, a Zurich-based corporation known for developing robotics and power and automation technologies, in partnership with the École polytechnique fédérale de Lausanne, a Swiss technology institute.

Getting to this test phase required the use of a complex mathematical model that takes into account variables ranging from the cost of batteries to the placement of recharging stations to electricity rates. The pilot project acts as a real-life proof for the concepts behind TOSA. Geneva is the first city expected to adopt a TOSA bus line as part of its regular service, with a start date sometime in 2017.