Comment

Electrification: an uncertain future

Dr Stuart Hillmansen, senior lecturer in electrical energy systems at the University of Birmingham, and head of the Traction Research Group as part of the Birmingham Centre for Railway Research and Education (BCRRE), considers the future of electrification in the country and the options left to take given recent government developments.

Electrification systems for railways provide a very effective means of supplying traction power to railway vehicles. The advantages for an electrified railway are numerous – increased reliability, better acceleration, greater passenger comfort, lower running costs, and the ability to take power from a range of sources. But despite the benefits, in comparison to other intensively-used rail ways we still have a relatively large amount of non-electrified track – and given recent developments, the extent of electrification is not likely to significantly increase in the coming years.

At the BCRRE, we have been conducting research covering a wide range of topics relating to electrified railways for a number of decades. Our power system simulators have been applied to railways around the world. Investigating the future for the electrified railway is therefore of significant interest to us at the university, and an important consideration for the industry in the longer term.

There are numerous articles which clinically dissect the various electrification projects that have suffered delays, costs overruns, cancelations and so on, and there is little to be gained from revisiting this discussion. Instead, we can consider some of the physical reasons as to why retrospective electrification on existing railways is challenging.

In our MSc module on Railway Traction Systems Design, I often ask the students to gaze at the running rails next time they are waiting at a platform. The next thing is to imagine what those rails mean to people with different points of view: the mechanical engineer is probably thinking about contact forces, wear, adhesion, fatigue; the civil engineer is thinking about the alignment, cant, and drainage; the signaller passing some tiny currents to detect the trains, and then the traction engineer comes along and sees two conductors suitable as a traction current return path. The challenge then is to somehow integrate the system so that all the engineering functions of the rail can be delivered.

OLE is another complex system. Mechanically, we need to consider its performance and present a stable overhead line to the train. It needs to work around corners, through tunnels, under bridges and through complex junctions. It also needs to be energised at 25,000 V and safe distances maintained around the line.

The result is that retrospective electrification is a complex design process that must somehow squeeze in an electrification system into a railway which was never designed to contain any electrification infrastructure. On my traction course, I also show the students clips from cab rides taken on newly developed high-speed lines around the world. Modern high-speed lines, particularly in the Far East, are highly modular in nature. Kilometre after kilometre are virtually identical. Electrification in this manner is much more straightforward, and I suspect much more cost effective.

The UK rail supply industry has invested considerable time and money into upskilling its workforce, and we now have a highly skilled and innovative electrification sector. The risk is that unless this is put to good use, then there will be an opportunity lost.

In the current political landscape, the future for electrification is quite uncertain (even though there is impetus to decarbonise the railway). The UK Rail Research and Innovation Network (UKRRIN), through its centres of excellence, is well placed to assist the industry in moving forward. Partners within UKRRIN have considered how we can ex tend the range of electrification through the introduction of novel technology, such as battery and hydrogen fuel cell range extenders. Another major area for consideration is the application of discontinuous electrification.

This would see the complex parts for electrification omitted from scheme designs and only the straightforward low-cost sections electrified. There are lots of challenges to overcome implementing a system such as this, but the UK rail supply industry has the right skills to deliver an ambitious project like this. It is important to recognise that this is not the end of electrification, but an opportunity to reimagine the interplay between the power system and the railway vehicle.

In the future, it is possible to visualise an electric backbone of the railway with electric trains capable of significant power autonomy to provide their own traction power on the sections of the network which are not electrified. If we can solve this for the Aberdeen to Penzance service, then the future of the railway power system will be secure.

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