Metro Railway gets batteries for back-up during a power failure inside the tunnel
Telegraph | 3 July 2025
Metro Railway has started installing a set of batteries that can chug a train stranded inside a tunnel on the north-south corridor (Blue Line) to the nearest station during a power failure.
The Battery Energy Storage System (BESS) is being set up at the sub-station near Central station, said an official. CESC supplies power to Metro Railway through sub-stations.
“Four such units arrived from Taiwan in the first week of May. They are being installed. The system should be in place by the end of July,” said a senior official of Metro Railway.
Each unit will have a capacity of 4MW. Once installed at Central sub-station, it can be used to power a train anywhere between Dum Dum and Tollygunge.
“The new system is a combination of inverters and advanced chemistry cell (ACC) batteries. The electricity generated with it can be used to haul stranded rakes from mid-tunnel to the next station in case of any power failure. The trains will not have to wait in underground tunnels or on the viaduct for restoration of power supply in case of a disruption,” the official said.
The minimum distance between two stations on the north-south corridor is around 700m and the maximum over two kilometres.
Sources in the carrier said the usual glitches that affect Metro rakes are localised and can be traced to the trains or the track or the signalling system.
But, the BESS is designed for a power failure of a much larger scale.
“The plan to have a back-up was conceived after the 2012 blackout which paralysed the country. This new BESS is equipped to provide back-up power to Metro Railway in case of a massive failure when the current supplier fails to provide power,” said a Metro engineer.
On July 30 and 31, 2012, India experienced one of the world’s largest blackouts, affecting half its people across 20 states. The northern and eastern grids collapsed, leading to power outages for over 10 hours.
“Now, if there is a power failure at one sub-station, then the next one can help. But this new system makes us ready for a scenario when there is a complete blackout,” the official said.
Advanced chemistry cells (ACC) can store electric energy as electrochemical or chemical energy and convert it back to electric energy when needed.
The Centre is invested in the new-generation technology to boost the country’s energy storage infrastructure.
The National Programme on Advanced Chemistry Cell battery storage was approved by the Union cabinet in May 2021 with a budgetary outlay of ₹18,100 crore.
The Metro project, approved by the Railway Board, is part of the national programme. Metro Railway is going to be the first zone in the Indian Railways and the first Metro in the country to implement the system, the carrier said.
The new technology involves lithium iron phosphate (LiFePO4) batteries, which are ideal to replace the older lead-acid batteries, said a Metro official.
“The new batteries take one-seventh of the space that the lead-acid batteries take. They are much lighter and more powerful than the older lot,” the official said.
In case of a power failure, the electrical traction that a stranded train will need to reach the nearest station cannot be provided with one lead-acid battery.
Each BESS has a lifespan of around 13 years after which, Metro engineers said, it can function for another 13 years at 80 per cent capacity.
“It is financially viable because it can save the peak-hour power demand. The battery can also be used as a storage system at night and then the stored energy can be used during the rush hours in the day,” said a Metro official.