University Researchers Evaluated Planning Options for a Bus Rapid Transit System in Medellin, Columbia.
Medellin, Columbia
A Planning Method for Partially Grid-Connected Bus Rapid Transit Systems Operating with In-Motion Charging Batteries
Summary Information
Grid-connected Systems (GCSs) are considered the core of mass transit worldwide, where the energy required by these systems is continually supplied by the electric grid. Bus Rapid Transit (BRT) could be considered the border between grid-connected operation and battery energy storage with either depot charging or In-motion Charging (IMC) options. Recognizing the scarcity of conductive IMC research in previous studies, the objective of this study was to present an optimization-based conductive IMC planning method to select the best combination of battery size, route segment electrification, and overnight depot charging infrastructure guaranteeing the proper operation of a high-demand BRT system. The proposed planning method was tested on a 13.5 km (8.4 mile) long BRT route with 20 stations, in Medellin, Colombia, using computational simulations in combination with real operational data in October 2019 from one of the existing single-decker Battery Electric Buses (BEB) that has been operating on the BRT line since April 23, 2018.
METHODOLOGY
In this study, the BEB considered was instrumented with a recording system, and operational data were collected on weekdays during its actual operation. Additionally, several performance measures such as battery voltage, battery current, motor power and energy, bus speed, and position were recorded for two full bus trips between two terminal stations. The planning model proposed in this study was implemented in an open-source computer programming language. To test the performance of the proposed optimization model for Medellin, 162 scenarios were analyzed combining different values for the cost parameters of the overhead line, the traction substation, the battery and the depot charger, as well as the battery charging power from the overhead lines.
FINDINGS
- Study results confirmed IMC BEB as a feasible option to consider especially for BRT and routes that have a potential modal shift towards buses.
- The study results indicated that the reduction of 200 kWh per battery bus in the case of Medellin would represent almost two tons of less weight to be moved on a distance of 250 km (about 155 miles) per day.
- Considering a fleet of 50 buses and 75,000 km/bus-year (46,603 miles/bus-year), the energy to move 7.5 mega tons-km (9.32 billion lbs-miles) would be saved.
