MTA Orders Electric-Hybrid Buses

The Massachusetts Bay Transportation Authority (MBTA) has ordered 194 electric-hybrid buses using the BAE Systems Series-ER extended range propulsion system. BAE said it is delivering its Series-ER system with a higher capacity battery to help Massachusetts reduce emissions and noise pollution on its transit bus routes.

The Series-ER system electric-hybrid buses are propelled by an electric motor, with power provided from a battery system. The battery is recharged by both an on-board generator set, using a down-sized internal combustion engine, and by regenerative energy produced when the bus slows to a stop.

By moving to a Series-ER system, a fleet can operate a portion of the day electrically with the engine off, reducing maintenance, idling, fuel use and emissions and eliminates the need for a charging infrastructure, BAE said.

BAE said the Series-ER uses the same components from the company’s Series-E hybrid-electric system. The Series-ER was developed to extend the electric travel time and distance without charging or investing in non-standardized charging infrastructure, without taking power off the grid, and without decreasing the number of passengers on board when adding extra battery packs.

The Series-ER extends the electric driving range and provides electric operating modes such as the extended EV range mode — driving on all-electric power in no- or low-emission areas. The extended range mode can be programmed according to each transit agency’s specifications, BAE said, to shut the engine off in a tunnel or other preferred areas.

BAE’s Accessory Power System (APS) option powers conventional electric loads, such as cooling fans and pumps, plus hybrid cooling systems. There is also a stop/start feature for bus accessories powered by APS, that can shut off the engine at stops to prevent idling and emissions. The BAE stop/start functions can be programmed with a global positioning system to automatically shut down the engine at specified locations.

A depot drive mode allows the engine to be shut down in specified locations to allow for electric drive only in low- and no-emission areas, when traveling < 500 yards.

The design of the BAE series hybrid system has no mechanical link between the diesel engine and the axle, with all power coming from the electric motor. Power flows in series from engine to generator to a traction motor.

The system is adaptable to all electric 35 to 40 ft. North American buses, BAE said, as well 12 to  18 m European buses, 60 ft. articulated buses and double deck buses.

 “Our new technology provides Massachusetts with an innovative and practical electric-hybrid solution,” said Steve Trichka, vice president and general manager of the Power and Propulsion Solutions business at BAE Systems. “This system provides clean electric operation that can be rapidly scaled now to help Massachusetts reap the benefits seen in thousands of buses worldwide.” mi


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