The London Underground has been at the forefront of using the latest technology to produce power for their stations for a number of years and is a keen proponent of cleaner greener energy use. At the London Olympics, Stratford station produced electricity using the walking of passengers and now they're trailing the generation of electricity from the subway train's brakes.
But how much energy can trains produce? According to the London Transport Authority, the system collects an average of one Megawatt hour (MWh) of energy per day, enough to power a station the size of Holborn for two days.
According to the Science Alert website, the system uses an inverter installed at the substation and works by feeding back the energy generated by the braking train into the main power stations. This is similar to the system in electric cars to increase their range.
But, not only does it directly save electricity, estimated to be five percent of annual electricity bill ($9 million), it also saves London Underground form having to cool their stations from the heat generated by the brakes.
Chris Tong, LU's Head of Power and Cooling, said "This state-of-the-art regenerative braking system has the potential to transform how we power stations across the network, unlocking massive power savings and significantly reducing our energy bills. We are committed to doing more to reduce our energy use and this technology - a world-first for metro railways - is one of a number of innovation we're embracing to lower our environmental impact."
After this successful trial, the system will be kept in place and presumably rolled-out across other stations in the network, helping to make the system a little more environmentally friendly. And now that this proof of concept has been show to be profitable, it's hoped that other mass transit systems around the world will adopt it in the future.