Metro Railway, Kolkata, has commissioned a Battery Energy Storage System (BESS) on the underground stretch of the Blue Line. This development is positioned as a major passenger-safety back-up during sudden power cuts or grid failures. The system has been introduced to improve energy efficiency and ensure passenger safety during power outages along the underground corridor between Dumdum and Mahanayak Uttam Kumar (Tollygunge).
What is the new system, and where is it installed?
As per the Metro Railway, Kolkata press release, the BESS has been commissioned at the Central Metro station on the Blue Line and is described as the first of its kind in Indian Railways and in eastern India. The system is rated at 4 MW and uses 6.4 MWh Lithium Iron Phosphate (LFP) batteries. It includes inverters and Advanced Chemistry Cell (ACC) batteries, which store electricity and can supply power during a grid failure.
A 6.4 MWh BESS has been implemented at the Central sub-station and comprises 88 racks with in-built fire-suppression systems.
How does this improve passenger safety during outages?
The core safety benefit is that if a train gets stranded in the tunnel due to a sudden power cut, the battery system is designed to move it to the next station so passengers can evacuate safely.
“The back-up application will haul passenger-loaded trains in case of any power outage and take the rake to the nearest station for safe evacuation of passengers,” Metro Railway Kolkata General Manager SS Mishra stated, as quoted by PTI.
The stored power can be used to haul rakes at speeds of up to 55 kmph from the mid-tunnel to the next station. The system will ensure that the tunnel ventilation control system continues to function, reducing risks of discomfort and suffocation during an outage.
Does it help beyond emergencies?
Yes, apart from emergency backup, the Metro press release highlights that BESS is expected to reduce carbon footprint and offer better energy efficiency than conventional generators. It is also designed to handle spikes in power demand, improve power factor and potentially reduce energy bills. The battery system has an estimated lifespan of around 14 years and is compact in design.
The Metro’s longer-term plan is to add another power-converter component so the BESS can also absorb excess regenerative energy (produced during train braking) that otherwise may be unused.