The energy technology that could overhaul tram systems

The Rail Manufacturing Cooperative Research Centre (CRC) has collaborated with CSIRO and the China Railway Rolling Stock Corporation (CRRC) to build a prototype energy management system that has the potential to replace overhead electricity lines and could possibly overhaul current light rail power systems.

The traditional method of powering trams is via overhead electricity lines, known as a catenary system. However, the catenary system poses a number of problems including its high cost, expensive maintenance program and its vulnerability to faults which, if they occur, can have a significant impact on the surrounding environment and can be hazardous.

An alternative energy management system prototype has been built at CSIRO’s Lindfield site in Sydney that is catenary-free. The system uses an onboard energy storage system to power the trams and this first full-sized prototype uses supercapacitors to power light rail tram vehicles.

CSIRO’s Electrical Machines Team Leader, Dr Howard Lovatt, said, “Eliminating the need for overhead electricity lines allows greater design flexibility thanks to fewer limitations on tram vehicle heights.

“It also means a reduction in infrastructure construction and maintenance costs, and the ability to store energy from regenerative braking back into the supercapacitors, which can further be used to power the tram.”

Innovation in action

CSIRO has partnered with CRRC on a suite of supercapacitor projects being overseen by the Rail Manufacturing CRC, an Australian Government Business Cooperative Research Centre program that connects industry with Australian research institutions.

The energy management system currently being tested aims to eliminate the catenary system by charging the vehicles when they are stopped at platforms.

Dr Larry Jordan, Research Director at Rail Manufacturing CRC, said when the tram is coming into the station, the vehicle communicates with the platform via a wireless telecommunications link.

“When the tram stops, its onboard supercapacitors are charged until the tram is ready to leave or the supercapacitors are full. Supercapacitors enable the trams to travel between platform stops, and potentially don’t even need to charge at every stop.”

Many different types of energy storage were considered and small prototypes of a few options were tested before the final supercapacitor prototype was decided.

“The characteristics that made the chosen supercapacitors ideal were a combination of a good life time, purchase price, size and weight. All these factors had to be weighed up for the competing solution,” Dr Lovatt said.

Competing with the catenary system

This catenary-free prototype offers many benefits over its traditional counterpart. Dr Jordan said the supercapacitors in the energy management system are capital cost effective when compared to the cost of the overhead wires in many of the scenarios studied.

“Supercapacitor-powered trams are likely more reliable, with a long service life and end-of-life timeframe that is easily predicted, monitored and serviced via a standard maintenance schedule,” Dr Jordan said.

“Overhead lines are unsightly, more vulnerable to trees falling and other unplanned occurrences such as vehicles hitting support poles or over-height trucks hitting the wires. High voltage, live wires coming down are potentially hazardous, while supercapacitors are relatively benign in comparison and are safe if punctured or crushed in an accident.”

If the rail industry went catenary-free, it could also have the potential to impact what rail and transport infrastructure is built.

“In addition to aesthetic, maintenance and safety concerns with overhead powerlines, there’s also the consideration around infrastructure power management, where powering trams via supercapacitors would have a different requirement for how power is drawn down, compared to the traditional overhead lines’ electricity load,” Dr Jordan said.

“I think many more cities will want a light rail if they don’t have to have the wires,” Dr Lovatt added.

Current testing and manufacturing

The prototype unit has been transported to China with the CRRC project team now working to manufacture the design. On a working tram, it is expected that each vehicle will require numerous energy storage units, which could provide many benefits for the rail industry.

“The prototype was made for Chinese rail manufacturer CRRC who are the rail experts who analyse the economic case, know about typical installation

An energy management system built by CRRC in China, based on the prototype technology delivered by CSIRO

and have contributed to the engineering in a fruitful partnership,” Dr Lovatt said.

CRRC is also already a major supplier of trains and trams to Australia.

Dr Jordan said the testing phase is focused on determining the reliability of the supercapacitors, confirming charge and discharge times and energy density, and testing the communications and software systems used to support the unit.

“At the specially-built full-scale test facility in China, the system can be tested at full power, which will identify how the scaled-up technology performs,” Dr Jordan said.

Initial project deliverables focused on developing the system architecture for cell balancing, charge and discharge profiles, and communications between the onboard system and the platform using commercially available supercapacitors which, unlike batteries, have the ability to charge and discharge very quickly for potentially 100,000 cycles.

To help make this technology commercially viable, the project has looked to enhance the performance of the energy management system that powers the supercapacitors. This has been done by reducing the unit’s weight, increasing the number of charge cycles and increasing the speed to charge and discharge the supercapacitors.

Implementing the technology in Australia

With a number of countries around the world now looking into the potential of using supercapacitors to power rail, Dr Jordan said there are hopes that the prototype technology can eventually be used in Australia.

“This project has real potential to be applied locally as both CSIRO and CRRC have the right to commercialise this technology in Australia. Further investigation of this technology in Australia is reliant on interest from state governments, tram manufacturers and construction businesses to test and validate the benefits of using this technology,” Dr Jordan said.

“Rolling out an entirely new power solution takes time and money, so for now the focus is on developing and proving the technology before next steps are considered.”

Rail Manufacturing CRC’s CEO, Dr Stuart Thomson, said this project was an example of how developing new technologies and knowledge is enhancing the rail manufacturing industry’s competitiveness.

“This project is a truly global collaboration which demonstrates the benefits of multinational organisations working with leading Australian research institutions,” Dr Thomson said.

Mr Chen Kai, Deputy General Manager of CRRC Qingdao Sifang Rolling Stock Research Institute, said, “Thanks to the collaboration with CSIRO since 2014, CRRC SRI has improved the technology of the traction system for catenary-free railway.”

CSIRO will continue to consult with CRRC on developing a full-scale system test in an effort to assess the commercial feasibility of the technology which will conclude by the end of 2018. Following this, CRRC and CSIRO can work to determine commercialisation or manufacturing opportunities for the supercapacitor technology moving forward.

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