The not-for-profit Byron Bay Railroad Company has unveiled a retrofitted diesel train, complete with electric motors and a 77kWh battery, to enable up to 100 passengers to travel a 3km trip in the Byron Bay area, on a disused section of railway.
The train - a 70-year-old famous Australian 'red rattler', built with lightweight aluminum fuselage - has had flexible solar panels installed on the roof, and is further supplied by a 30kW solar array installed at the main station to charge the battery. The train also has regenerative braking to capture energy when the train is slowing down, which will recycle a significant amount of energy back into the battery. One diesel engine was retained in case of failure, and for balance in the train itself.
Mains power, from a certified green power supplier, will contribute any additional power requirements, which may be necessary during winter or long stretches of cloudy conditions, so the train may not be completely solar-powered, all the time.
Weighing 80 tonnes without passengers, the train can complete 12-15 trips on a fully-charged battery.
The four million dollar (AUD) project was funded by a local businessman, Brian Flannery - who ironically made his fortune from coal.
"Hopefully it attracts people to Byron Bay," Mr Flannery said. "I think international tourists will come here to have a look at this world's first solar train. So let's see, in five years' time they'll probably still say I'm mad, but it's a bit of fun."
This isn't revolutionary, but it is unique. Of course, most trains are generally already electric via overhead wires or electrified rails, but using a system with locomotive power supplied by a battery charged by a fully solar system makes this a world first.
There are some catches - the 3,000 metre section of track is flat, with hills posing a problem for a battery-only system. It also only runs once per hour, allowing plenty of time to recharge, which wouldn't always be feasible in busier areas. And the panels on top of the train will supply only a very small fraction of the overall power demand.
But the point isn't to compare it to typical fast overland rail - the high-speed rail-lines criss-crossing Europe require significant energy - too high at this stage to consider battery-power. But there are numerous short-routes that this could work on to replace diesel-power or remove the need for overhead wires.
In any case, the starting point for many technologies is rarely a big achievement, but a small philanthropic project that can prove a concept and inspire others.
Other solar-powered and renewable elements on rails
An Indian-based project made news earlier in the year when engineers added solar panels to the roof of a diesel train, with energy from the sun powering systems including air conditioning and lights - saving nine tonnes of CO2 per year, per train. While the actual locomotive power is still from diesel, this is again another intriguing starting point to test the utility of solar panels on top of trains.
In the Netherlands, electric trains are 100% wind-powered, mostly from offshore wind farms, showing how we need to think not just about what's on a train roof or platform, but the wider grid.
Other concepts could be investigated as well - such as including solar panels along, or next to track lines, or adding more batteries to store renewables as well.
The future of mass-transport on trains is unlikely to be battery-powered any time soon, but the likelihood of renewable energy powering your underground, Métropolitain, U-Bahn or ICE train is much higher.