The system will be installed as part of a trial of inverting substation technology at Cloudesley Road substation in Islington, which will run until next year.
Hesop recovers braking energy from trains and returns it to the grid for use by accelerating trains. According to Alstom, the technology is designed to recover energy by the most efficient route permitted by the infrastructure, and allows more than 99% of braking energy to be fed back to the grid. This also reduces the amount of heat generated by the trains, a particular problem in the Victoria Line's deep small-profile tunnels.
The new fleet of Bombardier 2009 stock used on the Victoria Line is equipped with regenerative braking, and these trains already feed braking energy back to the grid, although Alstom says that adding Hesop to the power supply will allow residual energy currently wasted in braking resistors to be reused.
Hesop is already in use with Paris Transport Authority (RATP) and is installed at Pablo Picasso station on light rail line T1.