Hydraulic Accumulator Technology Boosts Transit Bus Fuel Economy

An investigation into the use of current hydraulic accumulator technology to regenerate braking energy in urban transit buses indicates that this system can improve vehicle fuel economy by approximately 50 percent. This savings plus that achieved through extended brake life can mean nearly $70,000 saved per vehicle over a 12-year lifetime.

Of the four system approaches investigated, that employed by the Technical University of Denmark is described in detail. It has the highest commercialization potential and would require only a short-term development program before introduction. It is also widely applicable to the transit bus retrofit market.

A theoretical analysis of the energy available for regeneration during the transit bus duty cycle; a computer simulation of system performance; and a cost/benefit analysis are discussed. Included is an extensive bibliography resulting from a worldwide literature search that produced over 240 papers on the subject.