One of the main reasons why electric vehicles are not being viewed to form part of public mass transportation is the need for frequent stops at charging depots. This limitation may soon become a thing of the past, as new technologies especially in the realm of wireless charging technology can make electric vehicles viable for mass transport use. The Weil am Rhein, Germany based company Conductix-Wampfler has introduced the public bus system of the future has been operating in the streets of Italian cities Torino and Genoa for the past ten years.
The Conductix-Wampfler IPT Charge system currently operates on thirty buses in the northern cities of Italy. The main recharging system uses a primary coil charging unit on the road surface of bus stops, terminals and hubs. There is secondary coil attached to the bus chassis that receives the charge. Each time a bus stops at a charging station, the coils are positioned within forty millimeters or about an inch of the half of each other.
Overnight the batteries of these buses are recharged at the bus depot and then recharged at each charging point during the bus route. This topping off would ensure sufficient range available for the battery to reach the next station as this refreshes the system between ten to fifteen percent of the battery capacity according to the German firm. This can even be done when passengers board and exit the vehicles.
The Torino bus route travels about 200 kilometers or 125 miles per day without a need to require a stop for a prolonged period or return to the depot for charging. This is not new, as early as the 1950s through the many urban areas throughout the United States. The electricity was delivered through overhead wires carrying power from the grid to the pivoting relays on the roofs of these buses. Quite a few remain as these electric systems have given way to buses that are powered by internal combustion engines.
The transfer system is done through inductive power transfer that Conductix-Wampfler sends 95 percent of the charge to the secondary coil, with the five percent loss considered as negligible. The central technology here is magnetic resonance coupling, which is also used in charge pads or mat technology in mobile devices. Even with the many companies putting their technological expertise into the field, only a very few companies have lasted for the last ten years successfully.
One of the major concerns is the health effect of the magnetic field on passengers and users. In response, the company says that the passengers and users are situated far from the relay coils and the magnetic field values are below the guidelines set by the International Commission on Non-Ionizing Radiation Protection, a nonprofit scientific watchdog group.
Another drawback is the cost of the electric buses compared to the cost of an internal combustion engine bus. Conductix-Wampfler currently estimates that the payback period of about four years at current prices of U.S. $9,000 per year compared to the U.S. $50,000 of diesel fuel vehicles.
Conductix-Wampfler is also working with Daimler to create a plug free charging system for passenger cars. It also has in the offing pilot and test projects of its technologies in two key cities in the United States, namely Los Angeles, CA and Chattanooga, TN.