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.