Battery powered trains could solve a range of problems on the UK’s rail network according to a Network Rail expert.
Speaking at the Metrorail Congress in London, Network Rail senior engineer James Ambrose said the technology had multiple benefits over electrified lines or diesel trains. He said to incorporate the trains onto the network less infrastructure would need to be built, maintained and inspected, the trains were quieter and more comfortable to ride and were safer and easier to maintain.
“Compared to electric or diesel, there are fewer moving parts which means less maintenance and a more reliable system,” he said. “There is increased route compatibility, therefore you could plug the gaps between electrified routes. If there’s a perturbation or a problem on the line you can carry the journey on and get passengers to the next station.”
The system could also be used to compliment an electrified line. By switching from using electrification to battery power a mile out of the station, Ambrose said it would avoid the need to build, maintain and upgrade the overhead cables in the area where it was most costly and disruptive to do so.
Full scale tests of the technology were carried out in 2015 under a consortium led by Network Rail. Targets on range, speed, acceleration and safety were all achieved.
The range of the trains is in the region of around 60km and to charge the batteries, the system uses regenerative braking – a technique which recoups and feeds the energy used when the train decelerates back into the battery – the battery would only need to be ‘topped up’ at each station with wireless charging technology in each three minute stop.
“The amount you need to charge the batteries depends on the duty cycles,” Ambrose said. “Every time you brake, you’re putting energy back in the battery. We were getting 25% recovery of energy, just from the service pattern of stop starting.”
Ambrose said the price of the trains was comparable to that of a diesel train, however with it came the additional benefits of a lower maintenance cost.
“Five years ago, battery power was expensive, but it’s not anymore, technology has made a massive difference,” he said.
The testing also looked at the second life of the battery.
“It’s also all about the second life of the batteries and knowing what you can use them for after,” he said. “Traction power can take a lot out of them, but they’re still fit for use. You can use them for line side equipment for controlling level crossings for example. It’s good for areas where you don’t want a power outage – and if there is, the system can still operate.”
On the back of the work which was carried out in the UK, the technology is now being rolled out in New Zealand. The country is currently tendering for a new fleet of battery powered trains after two years of research into the best solution for its rail network in Auckland. The central stretch of the network running through the city is being electrified however, it is using battery power to extend the benefits of electric trains to the outer reaches of the line.
However in the UK, only Mersey Rail has taken any steps to adopt the technology. It has recently procured one out of 30 new trains to have storage capability. To encourage the uptake, Ambrose wanted to see the technology written into the franchise agreement. Only when this happens will it move forward he said.
“You’ve got to have an operator that wants to do it and the product has got to be procured.”