It is possible that many
do not know that each metro train generates nearly a third of the power it
consumes to run.
The metro trains use
regenerative braking system technology and generate power whenever it applies
brakes and the power is mostly used by the train in the same electrical section
and what is left is fed back to metro rail’s 33KV network.
"The power is used for lighting and running auxiliary systems on
board," a metro rail official said. "In any transport system, fuel is
the biggest expenditure. But the regenerative braking system can reduce dependency
on the state grid. All our cars have traction systems to generate power; in
EMUs, only the locomotive does," the official said.
Again, there is something more to say. By
installing solar panels to generate 6MW metro rail further reduces its
dependency on non-renewable sources of energy.
In a regenerative braking system, three-phase traction motors in trains act as
generators whenever brakes are applied, turning the kinetic energy of the train
into electrical energy that goes into the overhead lines.
Metro rail now operates 13 trains on 29km of operational line on Koyambedu to
Alandur, Little Mount to Airport and Nehru Park to Thirumangalam
stretches, apart from running a direct service from Nehru Park to Airport every
30 minutes. By meeting 30% of power needs on its own, metro trains are cutting
down carbon emissions as it reduces dependency on power supplied by TNEB, which
relies on fossil fuels.
Delhi Metro, operating for 15 years, was reported to have prevented emission of
more than 90,000 tonnes of CO2 between 2004 and 2007 by using the regenerative
braking systems and by becoming the first railway project in the world to be
registered for carbon credits by the United Nations.
And by taking away four and two-wheelers off the road, the metro rail
indirectly contributes to reducing carbon foot print. It is said every
passenger using the metro instead of any two or four-wheeler contributes to
about 100gm of CO2 reduction for every 10km trip.
For a start, it has installed panels
with a 1MW capacity last year at its administrative building in Koyambedu. It
is expected to save Rs 1.12 crore each year. The rest of the panels will be
installed at 25 locations, including stations, and is expected to meet 90% of
annual energy requirements.
Metro rail's power requirements do not end with running trains. An air conditioned
underground station needs 3,500 units a day to function. The same amount a
train generates — 1,900 units — is enough to operate an elevated station. It
spends about Rs 28,000 a day to keep an underground station functioning and
about Rs 15,200 for an elevated station.
"We requested the state to give us a power subsidy but we received the
regular commercial rate. With solar energy, we can power some buildings and
workshops but the major power requirement is to operate trains, for which we
have to rely on other sources of power," an official said.