Quick Dips

Building
a Better Bus

A prototype electric bus developed at the University of Auckland's School of Engineering has won a major environmental prize. It generates less than 20% of the noise and exhaust pollution of existing diesel- and CNG-powered buses.

The Arthur Mead Environmental Award recognises "significant contributions" to preserving, conserving and improving the environment by engineers of the Auckland branch. ECNZ commissioned the prototype which was built by the Yellow Bus Company.

Professor John Boys and Dr Grant Covic of the Department of Electrical and Electronic Engineering spent two years converting the bus from diesel to a hybrid electric/CNG drive system.

The bus is powered by batteries whose range is extended by a small auxiliary CNG engine driving a small generator. It can carry up to 40 passengers at a top speed of 75 kilometres per hour. It can travel for 100-150 kilometres before the batteries need overnight recharging. Most electric vehicles are powered by a standard DC drive train system. This new prototype uses an AC motor drive which is more energy efficient, requires less maintenance and lasts longer.

Covic says the prototype bus is not yet economical enough to produce and operate en masse for urban public transport.

"However, improved battery technology -- in terms of cycle life, energy capability and cost -- will make it viable in the future."

He and Boys are now putting the lessons learned during their work on the electric bus to develop further electrical vehicle technology.