energy transport

Transport innovation of the week: solar trains

Solar power is used on the world’s rail networks in a variety of ways. In Britain we have the solar bridge at Blackfriars, and Belgium has a solar tunnel that feeds into the network. Indian railways are pioneering solar power to run train interiors. So far I’m not aware of anyone directly powering the trains with solar power, but there’s an interesting research project looking into that at the moment.

It springs from Repower Balcombe, 10:10‘s inspiring initiative to install community solar power in Britain’s first fracked village. They were looking at possible sites for a solar farm, and one of the most promising roofs in the area was on a long railway shed. The grid in the village was at full capacity and couldn’t handle that extra power, so a local engineer suggested that the solar panels could just feed straight into the railway.

That is apparently easier than you might think, as the output of a typical solar farm is similar to the operating voltage of a third rail on a typical suburban railway line. Solar power is produced during the day, when the trains are running – and the rail network is Britain’s largest consumer of electricity. There are also lots of industrial buildings, embankments and brownfield sites along railway lines that are suitable for solar panels, making this an apparently obvious opportunity that nobody had thought of.

If it’s obvious, why hasn’t it been done before? I suspect the main reason is economics. Solar power is dropping in price, and it’s only recently been competitive on price. Secondly, the tracks will need a dependable supply, as nobody wants trains stranded along the route because the sun has gone into the clouds. Some kind of buffer is needed in between, and battery storage has been expensive until very recently. New possibilities are opening up as the price of PV panels and battery storage falls. Beyond those considerations, perhaps the biggest obstacle will be the centralised power supply. Big customers call on big energy suppliers, and there’s a bias towards large scale infrastructure. Shifting towards a decentralised network of solar farms and smaller plants will require a change in mindset.

The technology to plug solar power directly into the rail network doesn’t exist yet, but it should be feasible. 10:10 and Imperial College London are currently investigating, along with various engineering partners. If Britain doesn’t do it first, somebody else will. As Ian Steadman points out in his article on trackside solar, that somebody could well be India. Direct trackside solar would bypass the need for a grid connection, which is the main obstacle to India’s bold electrification plans.

The Renewable Traction Project is underway at the moment, and they will report towards the end of 2017. I’ll write about it again when the results are out, because this is definitely an idea to keep an eye on.

10 comments

  1. Hey Jeremy. I love all things trains and all things solar, so this post hit two sweet spots. I love the idea of utilizing solar with trains and will be checking back as you delve deeper into this subject. Thanks for continuing to share some really interesting topics.

  2. I think a major problem with this idea is that trains throw up a lot of dirt at exactly the place where these would be which will soon coat the solar panels alongside the track. Cleaning them will be difficult as trackside work like that would require occupation of one running line if not both, meaning delays etc. Especially as where these would be would have live third rail.

    You could put the panels on a gantry over the railways but then they would be less accessible for maintenance and would also be more expensive, look at the pickle Network Rail has got into putting in catenary poles on the London to Cardiff route.

    1. A good point, and this is of course a problem that you get all across Africa and the Middle East, where the environment is naturally dustier. So far I’ve come across a variety of techniques, including an automated windscreen wiper type arrangement, or a nanoparticle coating that means dust won’t stick to them. NASA developed an electrostatic charge technique for clearing Mars dust off the panels on its rover. All of those would be better than sending a guy out with a broom.

      Knowing the railways, I imagine they’d have trouble with leaves too.

  3. When I asked, Transport for Greater Manchester told me that the Metrolink tram system runs on renewable electricity. I believe they have a contract with one of the companies that supplies 100% renewable power. Sadly the London – Manchester express traIns (Virgin) do not, but I see no reason, other than capacity, why a business like Ecotricity / Good energy etc could not sign up to power an electric railway system. The source of the power does not have to be right next to the tracks.

    1. No, there’s no reason why a company shouldn’t just buy an equivalent amount of renewable energy. The main advantage of this particular scheme is the direct connection, and being able to use marginal land and railway embankments which would otherwise be useless.

      1. Yes, I accept your point. When railway land and buildings are sold off (and there has been a lot of that), a condition could be that whatever is built on it / what ever use it is put to, must include solar PV or similar.

  4. Unfortunately, in the UK, misguided concerns about safety mean that further 3rd rail 750V electrification is unlikely until there is a return to commonsense. The installation of short sections of additional third rail electrification would achieve widespread network benefits in the south of England.

    Tramways, however, run on low voltage using overhead wires for the supply.

    However, existing systems could indeed act as a sink for excess supply from photovoltaic farms. Given the power consumption of even a single train, this is not, however, going to make much difference in the overall scheme of things. The best way to reduce power consumption on the railways is to keep speeds down to 120 kph, which is fast enough for most normal purposes especially when services are frequent; journey time savings from high speeds are soon dissipated in waiting at stations eg when changing trains or due to having to allow for delays to catch a train one has booked in advance.

    1. Indeed, this may end up on the list of things that we pioneer in Britain and other nations take on and run with. Internationally, it has huge potential, and some places may even get to lay down railway lines with this technology from the start.

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