London Underground is planning to cut its energy bill by 5% - saving up to £6m every year - by systematically harvesting the waste energy created by tube trains as they brake on entering stations.
A five-week trial at a Victoria Line electricity substation using modern 'inverter' technology to return otherwise lost energy to the power supply, delivered enough in one week to run Holborn Underground station – a large, busy interchange - for more than two days.
The daily capture of one Megawatt hour (MWh) of energy is equivalent to supplying the annual power needs of over 100 homes.
Claiming the scheme as 'a world first for metro railways', LU head of power and cooling, Chris Tong, said: 'This system has the potential to transform how we power stations across the Transport for London network, unlocking massive savings. We are committed to doing more to reduce our energy use'.
LU believes that the new technology could also reduce the amount of heat being generated by trains when they brake, which in turn would reduce costs of running LU's cooling systems and contribute to reducing its overall carbon footprint.