Transport for London (TfL) has announced plans to recycle enough brake energy on Tube trains to power an entire station.
Wasted energy will be harvested from Victoria Line trains to use the captured power, which bosses said could be enough to operate the the entire Holborn station for more than two days a week.
London Underground has already tested the inverter system during a five-week trial with results showing £6 million could be saved in a year.
TfL hopes to make further savings by not spending as much on artifical cooling systems used at stations when heat is produced from the brakes.
It comes as part of wider plans by Mayor Boris Johnson to make the Tube a greener form of travel.
Greenwich Power Station will be remodeled to enable it to convert into a low-carbon generator to link up to the Tube network.
Matthew Pencharz, deputy mayor for environment and energy, said: "The results of this project are really exciting and show huge potential for harnessing some of the immense energy in our Tube trains.
"The trial puts London at the cutting edge of this kind of technology and clearly demonstrates how energy from trains can be recovered to power Tube stations, making the network more environmentally friendly and cost effective."
