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Sunny prospects for solar railways?

With plans in place to electrify the entire UK train network, there are a number of barriers to overcome – not least the fact that in some areas, the electricity grid is already running at capacity. 

Could solar power provide a solution? Given that peak solar generation and peak demand for train travel have distinct parallels during a given day, it's an inviting prospect indeed, and one being explored in a world-first project involving Imperial College London and 10:10.  

On a grid of its own

The concept involves connecting solar panels directly to existing 'third rail' power lines, bypassing the grid. 

This is far from a simple undertaking. Third rails have an alternative purpose of being used for signalling – about as vital a function on the rail system as could be imagined. So there would need to be steadfast proof that putting power on the lines wouldn't affect that. 

There are also limitations in just how 'off grid' this can be. A backup power source would be required to run trains when its cloudy – and solar generation does vary over the course of a year, not just a day. This additional power might come from batteries, but it could also require the grid.

Another barrier to be overcoming in the possible 'scaling up' of such an idea is geography. Third rail powered lines are mostly found in the south east and north west of England – not quite the rural areas best suited for solar. 


All aboard! Energy storage goes on the rails

The resurgence of the battery powered train

Technical and financial test

Sunny rail road trackThis study is something of a triple test. It will provide answers on the suitability of renewable energy to power trains, and how best to create and manage local micro-grid systems. 

A good starting point is the fact that solar PV produces D/C power – the same that some trains use. No conversion necessary. 

Again, this is not quite a catch-all solution, as new investment from Network Rail is all in A/C. That's something on the researchers minds, as the third rail approach is just a starting point in this work. A/C options will be explored in due course.

But beyond the technical considerations, it will also be an examination of how solar schemes can be financed. With cuts to Feed-in Tariffs (FITs), making local solar investments has been made more difficult – especially an issue for the community energy sector. But the demand the incentive created has reduced the cost of panels, something schemes like this – which, if not grid connected, qualifies for no subsidy anyway—can capitalise on.

Power Purchase Agreements, or PPAs, look a good bet as an approach to keeping renewables' momentum rolling. These involve long-term contracts between energy producers and consumers, providing the security needed to get projects off the ground. A railway network would seem to be an ideal partner for such a deal, and this is something being further investigated here.

A rail-y good idea

This story fits into a worldwide trend for exploring how zero-carbon energy sources can fit into our transport future. Microgrid Knowledge has pointed out that the recent Solar Impulse flights were essentially a flying microgrid system, while Amtrak, which runs America's railways, is exploring its own concepts to cope with potential power outages. 

Bringing low-carbon transport to communities while providing proof of concept for a variety of technical approaches to green energy – there's not much to dislike here.

This UK partnership seems to be an investigation with potentially wide implications, not a nice novelty. The results of the feasibility study, available late this year, should make for a fascinating read. 

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Gary Hartley's picture
Gary Hartley is Energy Saving Trust's expert blogger. He has extensive experience researching and writing on a number of topics, with particular expertise in sustainable energy, policy, literature and sport. As well as providing regular blog content, Gary has also been published in numerous magazines and journals.

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