Ireland to get its first ‘zero emission’ diesel-electric hybrid buses

Order for so-called ‘clean’ vehicles has been placed with Scottish firm

The first “zero emission capability” buses to be used by Dublin Bus and Bus Éireann are to be deployed in Dublin and regional cities by the end of the year.

The National Transport Authority (NTA) has signed a deal for 100 Enviro400ER, double decker buses which allows for a further 500 such buses over the next four and-a-half years.

The total value of the full complement of 600 buses is about €273 million, with the cost of each of the first 100 buses coming in at about €450,000.

The Enviro400ER is a diesel-electric hybrid, capable of at least 2.5 kilometres continuous electric range with no exhaust emissions. It utilises the BAE Systems Series-ER hybrid system with a 32kWh lithium-ion battery that can be charged externally via a plug-in connection. The set-up meets meets the requirements of the EU’s Clean Vehicles Directive.

In addition to its continuous zero tailpipe emissions range, the Enviro400ER switches off its diesel engine at low speeds during approach to and departure from stops and when stationary.

The buses are supplied by Alexander Dennis Limited based in Larbert, Scotland, the UK’s largest bus and coach manufacturer.

The NTA has previously purchased nine hybrid diesel electric buses for service in Dublin and the regional cities. Three of these are deployed in Dublin, via Dublin Bus. These buses, introduced last May, use electricity captured as heat energy from the braking process, to reduce the amount of work that the low-emission diesel engine is required to do to propel the bus and power the on-board facilities. But these buses can not run in zero emissions mode.

The NTA previously announced fully electric double-decker buses could be seen on Cork streets within five years. It expects electric buses rather than biogas-fuelled vehicles are more likely to be deployed. Fully electric buses would have no diesel engine.

There are very few double-decker buses available in electric vehicle mode as they are larger buses and batteries are not good enough yet for the types of routes used in Ireland. But they are expected to be available in three or four years’ time.

Tim O'Brien

Tim O'Brien

Tim O'Brien is an Irish Times journalist