Are low carbon battery-powered trains the future?

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Dr Stuart Hillmansen, Senior Lecturer in Electrical Energy Systems, comments on the recent BusinessGreen report on low carbon battery-powered trains operating on the UK rail network. 

The Birmingham Centre for Railway Research and Education’s (BCRRE) Traction Systems Research Group has been investigating the potential for novel traction technologies for trains for some years. In 2009 the group completed a study for the Department for Transport in conjunction with TRL Ltd. to investigate the potential of a train powered entirely by batteries; the results of this work led the industry to begin to think more seriously about developing Independently Powered Electric Multiple Unit trains for the UK.

The UK rail network is investing a significant amount in increasing the quantity of routes that are electrified. In upcoming years, approximately 50% of routes will be electrified and 80% of the passengers kilometres delivered by electric trains. The benefits of electric traction, as opposed to diesel, are numerous and include; increased reliability, lower maintenance trains, increased train performance, not to mention better environmental credentials (lower noise, carbon, and local emissions). However, electrification remains expensive and retrofitting existing lines with 25,000 V electrification is particularly challenging, as we still use the Victorian infrastructure. Whilst the work involved in erecting the overhead system in open countryside is straightforward, the biggest challenge and expense we have is routing the high voltage cables through narrow tunnels and under bridges. 

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Which routes do we electrify? Ultimately, these decisions are based on an economic balance. Because of the way the UK railway has developed – we have more branch lines than other more recently constructed systems. Many of our mainline railway routes have several branch lines, feeding into a core, which leads into our major cities. Making a case to electrify the core is uncomplicated but extending to the branch lines can make the scheme uneconomic. For the services which do run on branch lines, we are then left with the only option of running diesel powered trains. This would involve decanting the passengers onto express services on the core, which may cause passenger disruption, or running a diesel vehicle under perfectly good electrification for the whole journey.

The newly developed Independently Powered Electric Multiple Unit (IPEMU), currently running a trial passenger service between Harwich International and Manningtree stations, could offer a solution to this problem by providing independent traction power for an electric train. When the train is on the electric network, the train takes power from the overhead system to provide traction and auxiliary power. A battery pack is also charged at the same time, which, once on the non-electrified network, can take over and provide the required power. This type of train has the advantages of an electric train with the go-anywhere ability of a diesel train.

It is not just the UK that faces these problems. The development of these technologies will, hopefully, encourage UK railway expertise for the rest of the world. BCRRE is working with a number of system integrators to investigate the potential for other novel power trains, for example diesel-battery and hydrogen. BCRRE’s work is based around the concept of a modular architecture that allows the power train to be changed during the life of a train, allowing the industry to take advantage of new power sources as they become available on the market.


By Dr Stuart Hillmansen, Senior Lecturer in Electrical Energy Systems

Notes

The article Low carbon battery-powered train carries first passengers was published by the Guardian online