Sustainable Trolleybus System: Rectifier Substation Technology Improvement for Energy Efficiency and Operational Cost Reduction

Coimbra's urban transportation system is the oldest system with trolleybuses currently in service at the Iberian Peninsula. Some of the infrastructure facilities date from the middle of last century and were not designed for today's energy concerns or energy-efficiency as is the case of "Montarroio" substation that still uses mercury arc rectifiers. Energy-efficiency substation's improvement is a key issue to maximize energy-savings. This paper describes the main studies and proposals made to achieve energy saving and cost reductions. One week long measurements at the two still active substations and the analysis of one year electricity bills were made. It was concluded that investments in new rectifiers are needed and that some of the studied options have a payback of just a few years. Implementing it can provide the rehabilitation of this means of transportation, assuming it as a real alternative to the currently mainstream systems, based on diesel bus.