It’s a revolution, Melbourne trams could go wire-free

Constantly improving supercapacitor technology is unburdening tram networks across the world, and provides Melbourne with the opportunity to expand its famed system.

If I asked a Melbournian what they’d think if the cities’ trams were to lose their overhead wires, perplexed they’d probably ask where we would hang our unique and famous Melbourne 'hook turn' signs?

Unbeknownst to Melbournians, cities across the globe are going wire-free, building new tram networks without overhead lines and even ripping them out in others. But you could be forgiven for having missed it here in Australia. Unfortunately no area of Australia’s transport sector deserve accolades for innovation, including wire-free trams (although there is a proposal to possibly use the technology on the new Dulwich Hill line in Sydney, however there's no firm commitment at this stage).

It all started at the turn of the century, when tram offerings from some of the biggest companies in the world started to include supercapacitor technology to even-out braking and acceleration, which causes spiking in conventional wired electric-driven transportation systems. Supercapacitors were installed in the roofs of some of the more advanced trams, offering very high efficiency regenerative braking and gross energy savings (which tram manufacturer Bombardier claims is around 30 per cent).

Increases in the power density of supercapacitors lead to a new opportunity to drop overhead lines altogether, as the trams could run solely using supercapacitors, which made tram systems easier to build and integrate into various urban environments.

Leading the charge for mass adoption of wireless trams has been the Spanish, with Trainelec, owned by rolling stock manufacturer Construcciones y Auxiliar de Ferrocarriles (CAF), which in 2011 delivered a completely wireless tram system through the centre of historic Seville, using the companies’ rapid charge accumulator – ACR – which is based on supercapacitor technology. A second system has been installed in Zaragoza. In both these systems the supercapacitors on board the trams are recharged from braking power and the sections of the network that have conventional overhead wires.

Although French company Alstom built the first modern wireless tram network for the City of Bordeaux back in 2003, its proprietary ‘buried third rail technology’ turned out to be terribly costly for building a large networks (in its original form) and was not being taken up anywhere else in the world. Following the success of supercapacitor systems, Alstom has now revised its solution, just keeping the buried third rail for the stops and combining the technology supercapacitors for the rest of the network. This offering will be delivered on a new Rio de Janeiro tramway; initially 28km in length it will run 32 wire-free Citadis trams.

Taking the technology to another level (and this is relevant to transport planners in Melbourne) is the Budapest Transport Centre which has decided to remove the overhead wires from the historic part of the Hungarian capital, instead ordering 37 wire-free, low-floor trams with an option for 87 additional supercapacitor trams from CAF.

In Taiwan, the City of Kaohsiung has commissioned a new tram network being designed and built by CAF to run without overhead wires – the network of 22km will run wire-free with supercapacitors onboard the trams being recharged at tram stops along the route. The CAF supercapacitor trams can go up to 4km (on flat terrain) without recharging and can tolerate many orders of magnitude more charge/discharge cycles than conventional chemical batteries.

In China the city of Nanjing’s lines will be 90 per cent wire-free with one line already operating and another one to be built, although they will run on a hybrid lithium-ion battery technology. In Haizhou district of Guangzhou, local rolling stock builder CSR Zhuzhou will supply at least 7 wire-free trams for a new line to be opened by the end of the year. And the Chinese capital, Beijing, is also turning to supercapacitor trams with a line to be opened by the end of the year with only half the track to be covered by overhead wires, relying on supercapacitors for powering trams over the rest of the route.

Although not currently cheap, the cost of supercapacitors is expected to drop considerably over the next couple of years. Soon supercapacitors will be able to store as much energy as today’s best conventional lithium-ion batteries using less expensive raw materials.

Tramways without overhead wires are likely to become considerably cheaper than overhead wire systems, as they will help to streamline planning and, obviously, do not require the construction of overhead infrastructure (which is particularly important in Australia with high constructions costs). Wire-free trams will also:

– increase safety, including reducing the incidence of trucks becoming tangled in overhead lines;

– reduce the need for clearances required for passing under bridges;

– removal of the need for significant ongoing investment in cathodic protection;

– use 30 per cent less power, and;

– have much better performance in bad weather conditions.

The ultimate solution that is being looked at by suppliers of these systems is contact-less recharging at stops that happens in less than 30 seconds (already available) combined with supercapacitors underneath the stops to reduce the need for dedicated electricity supply. Thus, a network with stops every 500m and a frequency of 20 trams per hour would need only a 15-20kW supply at each stop, a significant reduction on traditional systems that need to accommodate massive demand spikes during vehicle acceleration.

This new technology has the potential to immediately impact tram-mad Melbourne, which saw a proposal for a beautiful scenic tram route along Beaconsfield Parade between the Port Melbourne and St Kilda tram lines, but which was unfortunately cancelled due to cost and aesthetic concerns about overhead wires. This tourist-boosting tramway is now possible using vehicles from CAF of Spain, Alstom of France or CSR of China.  

This supercapacitor revolution in trams, something not seen since the switch from cable and horse drawn systems, is now available and could mean many hundreds of kilometres of new track could be easily deployed across Australia at much lower cost than before, along with the possible removal of costly electrical overhead infrastructure along key routes in the established Melbourne network.

These new trams have the potential to be a cheap solution to the congestion problems plaguing Australian cities, solving well-documented transport woes, unclogging roads, connecting disparate and ad hoc public transport and reducing local pollution. It’s time for Australia with Melbourne leading the charge to join the supercapacitor revolution! 

Matthew Wright is executive director of Zero Emissions Australia and a resident columnist at Climate Spectator.