Hybrid Buses for the Republic of Ireland Will Help Keep Things Green

The Republic of Ireland’s National Transport Authority has ordered 100 buses—with the order going as high as 600—from Alexander Dennis Ltd., UK-based bus and coach manufacturer, and BAE Systems.

This bus uses a hybrid system so that it can be propelled by electricity when entering low- or no-emissions zones. (Images: BAE Systems)

While that in itself may not be particularly interesting unless you happen to live in Dublin or somewhere else in the country and wish that the bus system had some new equipment, what is notable is that the BAE Systems contribution to this order is a hybrid system that utilizes a GPS system to switch the buses to electric-only power when they enter a low- or no-emissions zone.

Key point: Given the proliferation of such zones in cities around the world, this approach could become increasingly important.

The Series-ER system features a lithium-ion battery that stores energy; it can be fitted to the top of the bus in order to minimize space requirements. The series hybrid system also includes a generator, controller and electric motor. There is no mechanical link between the diesel engine and the axle (the power goes from the engine, to the generator to the traction motor). The setup means that the engine can be shutdown and the bus can travel on electricity for <500 yards.

Architecture of the BAE series hybrid system.

According to BAE, this hybrid system not only allows the zero-emissions travel, but because it is a hybrid and not a full EV, municipalities don’t have to install charging infrastructures for their bus fleets. (Buses with Series-ER technology are being deployed in U.S. cities including Boston and San Francisco.)