Alstom and London Underground have won two awards¹ in the last month for Hesop, Alstom’s advanced reversible power-supply substation. It has been in commercial service at the Cloudesley Road station for a year to serve the London Underground’s Victoria Line. Designed to deliver energy efficiency, Hesop also reduces infrastructure investment, limits CO2 emissions and decreases the temperature within the metro network.

Hesop works by converting and transferring any unused power, generated by the trains during braking, to the medium voltage loop for re-use within the network. The control system ensures that the energy is recovered via the most efficient route that the infrastructure will permit. Hesop allows to recover more than 99% of the traction energy generated during braking — which is usually lost, thereby reducing CO2 emissions through reduced energy consumption.

London Underground’s tunnels being small, most of the heat produced by the trains stays in the tunnel and surroundings. Hesop enables to reduce the number of braking resistors and therefore reduces tunnel heating by removing the heat source. Cooling equipment along the system can thereby be further optimized and the Tube becomes cooler without huge investments for additional equipment, such as ventilation shafts, according to Alstom officials.

“Should Hesop be installed more widely across the Underground, there are huge potential benefits in both energy reduction and also in relation to tunnel cooling, which I’m sure would be welcomed by commuters,” said Terence Watson, Alstom Managing Director in the UK & Ireland

Hesop benefits from four years of experience on the Paris tramway T1 line. Upcoming implementations include the Milan tramway and metro, Riyadh metro, Sydney tramway and Panama metro. 109 Hesop substations have been sold by Alstom so far.

(1) Alstom and London Underground won awards this year from both Railway Industry Awards and Transport Times in the UK.